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Sample records for aerosol vertical structure

  1. Changes in the vertical temperature structure associated with carbonaceous aerosols

    SciTech Connect

    Zhang, Y; Penner, J E; Chuang, C C; Santer, B D; Taylor, K

    2002-02-08

    Carbonaceous aerosols from anthropogenic activities act to both scatter and absorb solar radiation. It has been postulated that absorption by aerosols might significantly alter both the vertical temperature structure of the atmosphere and cloud fraction [Hansen et al. 1997, Ackerman et al, 2000]. Since both effects may alter the assessment of climate change associated with human activities, it is very important to understand both the magnitude and the mechanism by which carbonaceous aerosols affect climate. In this paper, we used a coupled climate and chemistry transport model to estimate the effects of carbonaceous aerosols on the vertical temperature structure and their effects on cloud fraction. A series Of control simulations were also carried out to compare the results of the model in which carbonaceous aerosols interact with climate with those in which they do not. We will present the temperature difference between simulations that include the effect of black carbon on the radiation field and those that do not, both at the surface and in the free troposphere. We will also discuss the change of temperature lapse rate and changes of cloud fraction associated with black carbon.

  2. The Vertical Structure, Sources, and Evolution of Aerosols in the Mediterranean Region

    NASA Astrophysics Data System (ADS)

    Roberts, Greg; Bourrianne, Thierry; Léon, Jean-François; Pont, Véronique; Mallet, Marc; Lambert, Dominique; Augustin, Patrick; Dulac, François; Junkermann, Wolfgang

    2013-04-01

    The VESSAER campaign (VErtical Structure and Sources of AERosols in the Mediterranean Region) was designed to characterize the different sources of aerosol in the Mediterranean Basin and assess the regional impact of aerosol on cloud microphysical and radiative properties. VESSAER was conducted on an ultra-light aircraft in summer 2012. Research activities included ground-based observations in the central and northern regions of Corsica, as well as aerosol lidar and sunphotometer measurements near the eastern coast. The main scientific goals were to investigate local versus long-range sources of aerosol and cloud condensation nuclei (CCN) and their vertical stratification in the lower troposphere, study evolution and ageing due to atmospheric processes, and determine aerosol direct radiative impacts over a larger spatial scale. The background aerosol concentrations (D > 0.01 um) within the boundary layer in Corsica were nearly 2000 cm^-3 and increased to ca. 104 cm^-3 during pollution events when back-trajectories originated from coastal areas in France and Italy and the Po Valley. Nearly all of these particles were CCN-active at 0.38% supersaturation, indicating a relatively hygroscopic aerosol. Vertical profiles of aerosol hygroscopicity revealed that ageing (with respect to CCN-activity) of European emissions occurred exclusively in the boundary layer. Within two days, the European emissions had become hygroscopic, probably a result of cloud processing. In contrast, aerosol hygroscopicity did not change as a function of transport time in elevated aerosol layers, suggesting that photochemical ageing of less hygroscopic material is relatively slow compared to ageing processes in the boundary layer. The vertical profiles clearly showed the long-range transport of dust from the Saharan Desert and pollution from the European continent, which were the two major sources of aerosol during the campaign. Two of the research flights coincided with CALIPSO overpasses, when

  3. Vertical structure and size distributions of Martian aerosols from solar occultation measurements

    NASA Technical Reports Server (NTRS)

    Chassefiere, E.; Blamont, J. E.; Krasnopol'skii, V. A.; Korablev, O. I.; Atreya, S. K.; West, R. A.

    1992-01-01

    Phobos 2 spectrometer measurements of solar occultations close to the evening terminator have furnished data on the vertical structure of the Martian aerosols near the northern spring equinox. Since the thermal structure derived from saturated IR profiles of water vapor does not allow the reaching of the CO2 frost point at cloud altitudes, said clouds' particles may be formed by H2O ice. Dust was also monitored at two wavelengths; it is assumed that the dust particles are levitated by eddy mixing. A parallel is drawn between these thin clouds and the polar mesospheric clouds observed on earth.

  4. Vertical Structure and Sources of Aerosols in the Mediterranean Region (VESSAER)

    NASA Astrophysics Data System (ADS)

    Roberts, G. C.; Junkermann, W.; Leon, J.; Pont, V.; Mallet, M.; Augustin, P.; Dulac, F.

    2012-12-01

    The Mediterranean region has been identified as one of the most prominent global "Hot-Spots" in future climate change projections [Giorgi and Lionello, 2008] and is particularly characterized by its vulnerability to changes in the water cycle. To this end, the VESSAER campaign (VErtical Structure and Sources of AERosols in the Mediterranean Region) was designed to characterize the different sources of aerosol in the Mediterranean Basin and assess their regional impact on cloud microphysical and radiative properties. VESSAER was conducted on the ENDURO-KIT ultra-light aircraft [W. Junkermann, 2001] in late June-early July 2012. Activities include ground observations as well as aerosol lidar and sunphotometer measurements in conjunction with the airborne measurements. The VESSAER campaign complements existing ChArMEx (http://charmex.lsce.ipsl.fr/ ; PI: F. Dulac) and HyMeX (http://www.hymex.org/ ; PI: V. Ducroc and P. Drobinski) activities, which are the target of many European research institutes in 2012 and 2013. The main scientific goals during VESSAER are to investigate local versus long-range sources of aerosol and cloud condensation nuclei (CCN) and their vertical stratification in the lower troposphere, use aerosol hygroscopicity to study their evolution due to atmospheric processes, and couple in-situ airborne measurements with ground-based remote sensing to determine aerosol direct radiative impacts over a larger spatial scale. The background aerosol concentrations within the boundary layer (BL) in Corsica are nearly 2000 cm-3 (Dp > 10 nm); 50 cm-3 (Dp > 300 nm). We were surprised to find that nearly all of these particles are CCN-active at 0.3% supersaturation and presume that ageing and/or cloud processing play a role in rendering the aerosol in the Mediterranean Basin more hygroscopic. The vertical profiles during VESSAER clearly show the long-range transport of dust from the Saharan Desert and pollution from the European continent -- which were the two

  5. Vertical Structure, Transport, and Mixing of Ozone and Aerosols Observed During NEAQS/ICARTT 2004

    NASA Astrophysics Data System (ADS)

    Senff, C. J.; Hardesty, R. M.; Brewer, W. A.; Alvarez, R. J.; Sandberg, S. P.; Tucker, S. C.; Intrieri, J. M.; Marchbanks, R. D.; McCarty, B. J.; Banta, R. M.; Darby, L. S.; White, A. B.

    2005-12-01

    During the 2004 New England Air Quality Study (NEAQS), which was conducted within the framework of the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) field experiment, airborne and shipborne lidar remote sensing instruments were deployed to characterize the 3-dimensional structure of ozone, aerosol, and low-level wind fields in the New England region. The 2004 measurements confirmed findings from the smaller-scale NEAQS 2002 experiment: the vertical structure and transport patterns of pollutant plumes from the Boston and New York City urban areas are strongly modified when they are advected over the Gulf of Maine. Because of strong vertical wind shear and a very stable atmosphere over the cold ocean water the plumes tend to get sheared apart and the resulting pieces of the plumes stay confined in layers aloft, isolated from the surface. Most notably, ozone concentrations aloft are very often significantly higher than ozone levels near the ocean surface. These elevated pollution plumes over the Gulf of Maine can affect air quality in coastal New England only when they are transported back over land. This can be accomplished by the large-scale flow or by local circulations such as the sea breeze. Once over land the elevated plumes may impact surface air quality by direct transport to higher terrain (e.g., Cadillac Mountain, ME) or by being fumigated down to the surface. Alternatively, but probably more rarely, an elevated pollution plume over the ocean may be mixed down to the surface by mechanically generated turbulence and then transported back to land within the marine boundary layer. We will use airborne and shipborne lidar remote sensing data to characterize the vertical distribution of ozone and aerosols over coastal New England, in particular the difference in plume structure over land and water. We will also show observational evidence for several of the processes described above that may mix down and transport

  6. Combining data from lidar and in situ instruments to characterize the vertical structure of aerosol optical properties

    NASA Technical Reports Server (NTRS)

    Redemann, J.; Turco, R. P.; Pueschel, R. F.; Browell, E. V.; Grant, W. B.

    1998-01-01

    Over the last decade, the quantification of tropospheric aerosol abundance, composition and radiative impacts has become an important research endeavor. For the most part, the interest in tropospheric aerosols is derived from questions related to the global and local (instantaneous) radiative forcing of climate due to these aerosols. One approach is to study local forcing under well-defined conditions, and to extrapolate such results to global scales. To estimate local aerosol forcing, appropriate radiative transfer models can be employed (e.g., the Fu-Liou radiative transfer code, [Fu and Liou, 1993]). In general, such models require information on derived aerosol properties [Toon, 1994]; namely the aerosol optical depth, single-scattering albedo, and asymmetry factor (phase function), all of which appear in the equations of radiative transfer. In this paper, we report on a method that utilizes lidar data and in situ aerosol size distribution measurements to deduce the vertical structure of the aerosol complex index of refraction in the near IR, thus identifying the aerosol type. Together with aerosol size distributions obtained in situ, the aerosol refractive index can be used to calculate the necessary derived aerosol properties. The data analyzed here were collected during NASA's PEM West-B (Pacific Exploratory Mission) experiment, which took place in February/March 1994. The platform for the measurements was the NASA DC-8 aircraft. The primary goal of the PEM West missions [Browell et al., 1996] was the assessment of potential anthropogenic perturbations of the chemistry in the Pacific Basin troposphere. For this purpose the timing of PEM West-B corresponded to the seasonal peak in transport from the Asian continent into the Pacific basin [Merrill et al., in press]. This period normally occurs during Northern Hemisphere spring, when the Japan jet is well developed.

  7. Vertical Structure of Aerosols and Mineral Dust Transport Over the Bay of Bengal Using Multi-Satellite Observations.

    NASA Astrophysics Data System (ADS)

    Naduparambil Bharathan, L.

    2015-12-01

    Bay-of-Bengal (BoB), a small oceanic region Eat to Indian land mass, surrounded by heavily inhabited land masses, experiences different types of air-masses in different seasons of contrasting wind patterns, which makes it a region of large heterogeneity in the context of regional climate forcing due to atmospheric aerosols. Heterogeneity of aerosol system over the Bay of Bengal is mainly determined by three distinct source regions, which are east coast of India/central India, China/east Asia and Arabian region. Continental aerosols transported through higher elevations over BoB lead to significant impacts in regional climate by modifying the vertical thermal structure of the atmosphere and associated circulation dynamics. The study aims at a comprehensive understanding on the spatial and temporal heterogeneity of elevated aerosol over the BoB using the observations of Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). Being capable of short wave scattering and long wave absorption, mineral dust aerosols can affects the energetics of the atmosphere over any region.Owing to its influence on Indian monsoon rainfall and regional climate, the study aims to comprehend on the spatial and seasonal variation of mineral dust transport over the Bay of Bengal. vertical distribution of the dust extinction coefficient over the Bay of Bengal for all seasons, is derived, using a dust separation scheme that uses the depolarization measurements, a priori information on lidar ratio of dust, depolarization ratio of dust and that of non-dust aerosols. Being highly non-spherical, mineral dust significantly depolarize the radiation and possess distinct range of depolarization ratio. This property of dust is made use to identify and quantify dust over the study region. Seasonal variation of dust fraction over the Bay of Bengal is estimated seperately from CALIPSO back scattering coefficients

  8. Investigations of boundary layer structure, cloud characteristics and vertical mixing of aerosols at Barbados with large eddy simulations

    NASA Astrophysics Data System (ADS)

    Jähn, Michael; Muñoz-Esparza, Domingo; Chouza, Fernando; Reitebuch, Oliver; Knoth, Oswald; Haarig, Moritz; Ansmann, Albert; Tegen, Ina

    2016-04-01

    Large eddy simulations (LESs) with ASAM (All Scale Atmospheric Model) are performed for the area of the Caribbean island Barbados to investigate island effects on boundary layer modification, cloud generation and vertical mixing of aerosols. In order to generate inflow turbulence consistent with the upstream marine boundary layer forcing, we use the cell perturbation method based on finite amplitude potential temperature perturbations. This method is now also validated for moist boundary layer simulations with open lateral boundary conditions. Observational data obtained from the SALTRACE (Saharan Aerosol Long-range Transport and Aerosol-Cloud-Interaction Experiment) field campaign is used for both model initialization and comparisons. Several sensitivity tests are carried out to demonstrate the problems related to "gray zone modeling" or when the turbulent marine boundary layer flow is replaced by laminar winds. Additional simulation cases deal with modified surface characteristics and their impacts on the simulation results. Saharan dust layers that reach Barbados via long-range transport over the North Atlantic are included as passive tracers in the model. Effects of layer thinning, subsidence and turbulent downward transport near the layer bottom at z ≈ 1800 m become apparent. The exact position of these layers and strength of downward mixing is found to be mainly controlled atmospheric stability (especially inversion strength) and wind shear. Comparisons of LES model output with lidar data show similarities in the downwind vertical wind structure and accurately reproduces the development of the daytime convective boundary layer measured by the Raman lidar.

  9. Retrieving the Vertical Structure of the Effective Aerosol Complex Index of Refraction from a Combination of Aerosol in Situ and Remote Sensing Measurements During TARFOX

    NASA Technical Reports Server (NTRS)

    Redemann, J.; Turco, R. P.; Liou, K. N.; Russell, P. B.; Bergstrom, R. W.; Schmid, B.; Livingston, J. M.; Hobbs, P. V.; Hartley, W. S.; Ismail, S.; Ferrare, R. A.; Browell, E. V.

    2000-01-01

    The largest uncertainty in estimates of the effects of atmospheric aerosols on climate stems from uncertainties in the determination of their microphysical properties, including the aerosol complex index of refraction, which in turn determines their optical properties. A novel technique is used to estimate the aerosol complex index of refraction in distinct vertical layers from a combination of aerosol in situ size distribution and remote sensing measurements during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX). In particular, aerosol backscatter measurements using the NASA Langley LASE (Lidar Atmospheric Sensing Experiment) instrument and in situ aerosol size distribution data are utilized to derive vertical profiles of the "effective" aerosol complex index of refraction at 815 nm (i.e., the refractive index that would provide the same backscatter signal in a forward calculation on the basis of the measured in situ particle size distributions for homogeneous, spherical aerosols). A sensitivity study shows that this method yields small errors in the retrieved aerosol refractive indices, provided the errors in the lidar-derived aerosol backscatter are less than 30% and random in nature. Absolute errors in the estimated aerosol refractive indices are generally less than 0.04 for the real part and can be as much as 0.042 for the imaginary part in the case of a 30% error in the lidar-derived aerosol backscatter. The measurements of aerosol optical depth from the NASA Ames Airborne Tracking Sunphotometer (AATS-6) are successfully incorporated into the new technique and help constrain the retrieved aerosol refractive indices. An application of the technique to two TARFOX case studies yields the occurrence of vertical layers of distinct aerosol refractive indices. Values of the estimated complex aerosol refractive index range from 1.33 to 1.45 for the real part and 0.001 to 0.008 for the imaginary part. The methodology devised in this study

  10. Retrieving the Vertical Structure of the Effective Aerosol Complex Index of Refraction from a Combination of Aerosol in Situ and Remote Sensing Measurements During TARFOX

    NASA Technical Reports Server (NTRS)

    Redemann, J.; Turco, R. P.; Liou, K. N.; Russell, P. B.; Bergstrom, R. W.; Schmid, B.; Livingston, J. M.; Hobbs, P. V.; Hartley, W. S.; Ismail, S.

    2000-01-01

    The largest uncertainty in estimates of the effects of atmospheric aerosols on climate stems from uncertainties in the determination of their microphysical properties, including the aerosol complex index of refraction, which in turn determines their optical properties. A novel technique is used to estimate the aerosol complex index of refraction in distinct vertical layers from a combination of aerosol in situ size distribution and remote sensing measurements during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX). In particular, aerosol backscatter measurements using the NASA Langley LASE (Lidar Atmospheric Sensing Experiment) instrument and in situ aerosol size distribution data are utilized to derive vertical profiles of the 'effective' aerosol complex index of refraction at 815 nm (i.e., the refractive index that would provide the same backscatter signal in a forward calculation on the basis of the measured in situ particle size distributions for homogeneous, spherical aerosols). A sensitivity study shows that this method yields small errors in the retrieved aerosol refractive indices, provided the errors in the lidar derived aerosol backscatter are less than 30% and random in nature. Absolute errors in the estimated aerosol refractive indices are generally less than 0.04 for the real part and can be as much as 0.042 for the imaginary part in the case of a 30% error in the lidar-derived aerosol backscatter. The measurements of aerosol optical depth from the NASA Ames Airborne Tracking Sunphotometer (AATS-6) are successfully incorporated into the new technique and help constrain the retrieved aerosol refractive indices. An application of the technique to two TARFOX case studies yields the occurrence of vertical layers of distinct aerosol refractive indices. Values of the estimated complex aerosol refractive index range from 1.33 to 1.45 for the real part and 0.001 to 0.008 for the imaginary part. The methodology devised in this study

  11. New Measurements of Aerosol Vertical Structure from Space using the NASA Geoscience Laser Altimeter System (GLAS): Applications for Aerosol Transport Models

    NASA Technical Reports Server (NTRS)

    Welton, E. J.; Spinhime, J.; Palm, S.; Hlavka, D.; Hart, W.; Ginoux, P.; Chin, M.; Colarco, P.

    2004-01-01

    In the past, satellite measurements of aerosols have only been possible using passive sensors. Analysis of passive satellite data has lead to an improved understanding of aerosol properties, spatial distribution, and their effect on the earth,s climate. However, direct measurement of aerosol vertical distribution has not been possible using only the passive data. Knowledge of aerosol vertical distribution is important to correctly assess the impact of aerosol absorption, for certain atmospheric correction procedures, and to help constrain height profiles in aerosol transport models. On January 12,2003 NASA launched the first satellite-based lidar, the Geoscience Laser Altimeter System (GLAS), onboard the ICESat spacecraft. GLAS is both an altimeter and an atmospheric lidar, and obtains direct measurements of aerosol and cloud heights. Here we show an overview of GLAS, provide an update of its current status, and discuss how GLAS data will be useful for modeling efforts. In particular, a strategy of using GLAS to characterize the height profile of dust plumes over source regions will be presented, along with initial results. Such information can be used to validate and improve output from aerosol transport models. Aerosol height profile comparisons between GLAS and transport models will be shown for regions downwind of aerosol sources. We will also discuss the feasibility of assimilating GLAS profiles into the models in order to improve their output.

  12. New Measurements of Aerosol Vertical Structure from Space Using the NASA Geoscience Laser Altimeter System (GLAS): Applications for Aerosol Transport Models

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; Ginoux, Paul; Colarco, Peter; Chin, Mian; Spinhirne, James D.; Palm, Steven P.; Hlavka, Dennis; Hart, William

    2003-01-01

    In the past, satellite measurements of aerosols have only been possible using passive sensors. Analysis of passive satellite data has lead to an improved understanding of aerosol properties, spatial distribution, and their effect on the earth s climate. However, direct measurement of aerosol vertical distribution has not been possible using only the passive data. Knowledge of aerosol vertical distribution is important to correctly assess the impact of aerosol absorption, for certain atmospheric correction procedures, and to help constrain height profiles in aerosol transport models. On January 12,2003 NASA launched the first satellite-based lidar, the Geoscience Laser Altimeter System (GLAS), onboard the ICESat spacecraft. GLAS is both an altimeter and an atmospheric lidar, and obtains direct measurements of aerosol and cloud heights. Here we show an overview of GLAS, provide an update of its current status, and discuss how GUS data will be useful for modeling efforts. In particular, a strategy of using GLAS to characterize the height profile of dust plumes over source regions will be presented, along with initial results. Such information can be used to validate and improve output from aerosol transport models. Aerosol height profile comparisons between GLAS and transport models will be shown for regions downwind of aerosol sources. We will also discuss the feasibility of assimilating GLAS profiles into the models in order to improve their output,

  13. Investigations of boundary layer structure, cloud characteristics and vertical mixing of aerosols at Barbados with large eddy simulations

    NASA Astrophysics Data System (ADS)

    Jähn, M.; Muñoz-Esparza, D.; Chouza, F.; Reitebuch, O.

    2015-08-01

    Large eddy simulations (LES) are performed for the area of the Caribbean island Barbados to investigate island effects on boundary layer modification, cloud generation and vertical mixing of aerosols. Due to the presence of a topographically structured island surface in the domain center, the model setup has to be designed with open lateral boundaries. In order to generate inflow turbulence consistent with the upstream marine boundary layer forcing, we use the cell perturbation method based on finite amplitude perturbations. In this work, this method is for the first time tested and validated for moist boundary layer simulations with open lateral boundary conditions. Observational data obtained from the SALTRACE field campaign is used for both model initialization and a comparison with Doppler wind lidar data. Several numerical sensitivity tests are carried out to demonstrate the problems related to "gray zone modeling" when using coarser spatial grid spacings beyond the inertial subrange of three-dimensional turbulence or when the turbulent marine boundary layer flow is replaced by laminar winds. Especially cloud properties in the downwind area west of Barbados are markedly affected in these kinds of simulations. Results of an additional simulation with a strong trade-wind inversion reveal its effect on cloud layer depth and location. Saharan dust layers that reach Barbados via long-range transport over the North Atlantic are included as passive tracers in the model. Effects of layer thinning, subsidence and turbulent downward transport near the layer bottom at z ~ 1800 m become apparent. The exact position of these layers and strength of downward mixing is found to be mainly controlled atmospheric stability (especially inversion strength) and wind shear. Comparisons of LES model output with wind lidar data show similarities in the formation of the daytime convective plume and the mean vertical wind structure.

  14. Investigations of boundary layer structure, cloud characteristics and vertical mixing of aerosols at Barbados with large eddy simulations

    NASA Astrophysics Data System (ADS)

    Jähn, M.; Muñoz-Esparza, D.; Chouza, F.; Reitebuch, O.; Knoth, O.; Haarig, M.; Ansmann, A.

    2016-01-01

    Large eddy simulations (LESs) are performed for the area of the Caribbean island Barbados to investigate island effects on boundary layer modification, cloud generation and vertical mixing of aerosols. Due to the presence of a topographically structured island surface in the domain center, the model setup has to be designed with open lateral boundaries. In order to generate inflow turbulence consistent with the upstream marine boundary layer forcing, we use the cell perturbation method based on finite amplitude potential temperature perturbations. In this work, this method is for the first time tested and validated for moist boundary layer simulations with open lateral boundary conditions. Observational data obtained from the SALTRACE field campaign is used for both model initialization and a comparison with Doppler wind and Raman lidar data. Several numerical sensitivity tests are carried out to demonstrate the problems related to "gray zone modeling" when using coarser spatial grid spacings beyond the inertial subrange of three-dimensional turbulence or when the turbulent marine boundary layer flow is replaced by laminar winds. Especially cloud properties in the downwind area west of Barbados are markedly affected in these kinds of simulations. Results of an additional simulation with a strong trade-wind inversion reveal its effect on cloud layer depth and location. Saharan dust layers that reach Barbados via long-range transport over the North Atlantic are included as passive tracers in the model. Effects of layer thinning, subsidence and turbulent downward transport near the layer bottom at z ≈ 1800 m become apparent. The exact position of these layers and strength of downward mixing is found to be mainly controlled atmospheric stability (especially inversion strength) and wind shear. Comparisons of LES model output with wind lidar data show similarities in the downwind vertical wind structure. Additionally, the model results accurately reproduce the

  15. Measurements of the Vertical Structure of Aerosols and Clouds Over the Ocean Using Micro-Pulse LIDAR Systems

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; Spinhirne, James D.; Campbell, James R.; Berkoff, Timothy A.; Bates, David; Starr, David OC. (Technical Monitor)

    2001-01-01

    The determination of the vertical distribution of aerosols and clouds over the ocean is needed for accurate retrievals of ocean color from satellites observations. The presence of absorbing aerosol layers, especially at altitudes above the boundary layer, has been shown to influence the calculation of ocean color. Also, satellite data must be correctly screened for the presence of clouds, particularly cirrus, in order to measure ocean color. One instrument capable of providing this information is a lidar, which uses pulses of laser light to profile the vertical distribution of aerosol and cloud layers in the atmosphere. However, lidar systems prior to the 1990s were large, expensive, and not eye-safe which made them unsuitable for cruise deployments. During the 1990s the first small, autonomous, and eye-safe lidar system became available: the micro-pulse lidar, or MPL. The MPL is a compact and eye-safe lidar system capable of determining the range of aerosols and clouds by firing a short pulse of laser light (523 nm) and measuring the time-of-flight from pulse transmission to reception of a returned signal. The returned signal is a function of time, converted into range using the speed of light, and is proportional to the amount of light backscattered by atmospheric molecules (Rayleigh scattering), aerosols, and clouds. The MPL achieves ANSI eye-safe standards by sending laser pulses at low energy (micro-J) and expanding the beam to 20.32 cm in diameter. A fast pulse-repetition-frequency (2500 Hz) is used to achieve a good signal-to-noise, despite the low output energy. The MPL has a small field-of-view (< 100 micro-rad) and signals received with the instrument do not contain multiple scattering effects. The MPL has been used successfully at a number of long-term sites and also in several field experiments around the world.

  16. Influence of aerosol vertical distribution on radiative budget and climate

    NASA Astrophysics Data System (ADS)

    Nabat, Pierre; Michou, Martine; Saint-Martin, David; Watson, Laura

    2016-04-01

    Aerosols interact with shortwave and longwave radiation with ensuing consequences on radiative budget and climate. Aerosols are represented in climate models either using an interactive aerosol scheme including prognostic aerosol variables, or using climatologies, such as monthly aerosol optical depth (AOD) fields. In the first case, aerosol vertical distribution can vary rapidly, at a daily or even hourly scale, following the aerosol evolution calculated by the interactive scheme. On the contrary, in the second case, a fixed aerosol vertical distribution is generally imposed by climatological profiles. The objective of this work is to study the impact of aerosol vertical distribution on aerosol radiative forcing, with ensuing effects on climate. Simulations have thus been carried out using CNRM-CM, which is a global climate model including an interactive aerosol scheme representing the five main aerosol species (desert dust, sea-salt, sulfate, black carbon and organic matter). Several multi-annual simulations covering the past recent years are compared, including either the prognostic aerosol variables, or monthly AOD fields with different aerosol vertical distributions. In the second case, AOD fields directly come from the first simulation, so that all simulations have the same integrated aerosol loads. The results show that modifying the aerosol vertical distribution has a significant impact on radiative budget, with consequences on global climate. These differences, highlighting the importance of aerosol vertical distribution in climate models, probably come from the modification of atmospheric circulation induced by changes in the heights of the different aerosols. Besides, nonlinear effects in the superposition of aerosol and clouds reinforce the impact of aerosol vertical distribution, since aerosol radiative forcing depends highly upon the presence of clouds, and upon the relative vertical position of aerosols and clouds.

  17. A Multi-Instrument Approach for Characterizing the Vertical Structure of Aerosol Properties: Case Studies in the Pacific Basin Troposphere

    NASA Technical Reports Server (NTRS)

    Redemann, J.; Turco, R. P.; Pueschel, R. F.; Fenn, M. A.; Browell, E. V.; Grant, W. B.

    1998-01-01

    During February/March 1994, a series of aircraft-based aerosol measurements were carried out in the Pacific Basin troposphere using a differential absorption lidar system deployed by NASA Langley, and optical spectrometer probes and a wire-impactor system operated by NASA Ames. A modified Klett inversion algorithm was applied to extract altitude profiles of aerosol backscattering from the IR lidar signal. The algorithm that we have designed for this purpose utilizes the in situ aerosol measurements to normalize the lidar profile at the aircraft altitude and to supply the lidar ratio as a function of height. The lidar-derived aerosol backscattering coefficients were then compared to the backscattering coefficients calculated from the in situ measurements. During several local aircraft descents, we found good agreement between the remote lidar and in situ results for the absolute value of the aerosol backscattering coefficient and its altitude variation only when we allowed for several layers with different aerosol refractive indices. The agreement validates our lidar calibration method and provides an indication of the variation in aerosol refractive index as a function of altitude. Two of the three case studies performed in this paper reveal layers of anthropogenic aerosols transported long distances into the Pacific Basin troposphere. A third case implies the existence of a layer of dustlike aerosol particles in the lower troposphere, most likely of Asian origin.

  18. A multi-instrument approach for characterizing the vertical structure of aerosol properties: Case studies in the Pacific Basin troposphere

    NASA Astrophysics Data System (ADS)

    Redemann, J.; Turco, R. P.; Pueschel, R. F.; Fenn, M. A.; Browell, E. V.; Grant, W. B.

    1998-09-01

    During February/March 1994, a series of aircraft-based aerosol measurements were carried out in the Pacific Basin troposphere using a differential absorption lidar system deployed by NASA Langley, and optical spectrometer probes and a wire-impactor system operated by NASA Ames. A modified Klett inversion algorithm was applied to extract altitude profiles of aerosol backscattering from the IR lidar signal. The algorithm that we have designed for this purpose utilizes the in situ aerosol measurements to normalize the lidar profile at the aircraft altitude and to supply the lidar ratio as a function of height. The lidar-derived aerosol backscattering coefficients were then compared to the backscattering coefficients calculated from the in situ measurements. During several local aircraft descents, we found good agreement between the remote lidar and in situ results for the absolute value of the aerosol backscattering coefficient and its altitude variation only when we allowed for several layers with different aerosol refractive indices. The agreement validates our lidar calibration method and provides an indication of the variation in aerosol refractive index as a function of altitude. Two of the three case studies performed in this paper reveal layers of anthropogenic aerosols transported long distances into the Pacific Basin troposphere. A third case implies the existence of a layer of dustlike aerosol particles in the lower troposphere, most likely of Asian origin.

  19. Vertical Profile of Aerosol Properties at Pico Mountain, Azores

    NASA Astrophysics Data System (ADS)

    Wright, K.; Mazzoleni, C.; Mazzoleni, L. R.; Dzepina, K.; Hueber, J.; China, S.; Sharma, N.

    2013-12-01

    Pico Mountain (2325m asl) is a dormant volcano in the archipelago of the Azores1500 km west of Lisbon, Portugal in the North Atlantic. It differs from typical mountain ranges such as the Alps or the Rockies, which are large and present a complex orography. Pico Mountain has a simple cone-like structure with only one main peak and is thousands of kilometers away from any other significant mountain range. In summer months, it is typical for air masses to move around the mountain rather than traveling up its face. This implies that often the peak of the mountain lies above the marine boundary layer in the free troposphere, while the lower part of the mountain is affected by marine clouds and marine air-masses. An atmospheric monitoring station, the Pico Mountain Observatory was established in 2001 in the summit caldera of the volcano at 2225m above sea level. The observatory is far from large populations or pollution sources, which makes the station ideal to study atmospheric gases and aerosols transported over long-ranges in the free troposphere. The station is reachable only by foot following a steep and strenuous hiking trail. In the summer of 2013 we began to collect vertical profiles of aerosol by carrying an instrumented backpack up to the summit of the mountain, with the goal of studying the vertical structure of atmospheric aerosols from the marine boundary layer to the free troposphere. The backpack was carried from the base of trail at 1200m asl. The backpack was equipped with the following instruments: 1. Nephelometer to measure light scattering from aerosol 2. 2-size optical particle counter (300-500 nm) 3. Portable micro-aethalometer to measure absorbing aerosols 4. SEM/TEM sampler to collect particles for off-line electron microscopy analysis 5. Battery powered data logger to measure relative humidity, temperature and pressure 6. GPS tracking device We provide a preliminary analysis of data collected in 2013 to gain insight on the vertical distribution

  20. Lidar Observations of the Vertical Structure of Ozone and Aerosol during Wintertime High-Ozone Episodes Associated with Oil and Gas Exploration in the Uintah Basin

    NASA Astrophysics Data System (ADS)

    Senff, C. J.; Langford, A. O.; Banta, R. M.; Alvarez, R. J.; Weickmann, A.; Sandberg, S.; Marchbanks, R. D.; Brewer, A.; Hardesty, R. M.

    2013-12-01

    The Uintah Basin in northeast Utah has been experiencing extended periods of poor air quality in the winter months including very high levels of surface ozone. To investigate the causes of these wintertime ozone pollution episodes, two comprehensive studies were undertaken in January/February of 2012 and 2013. As part of these Uintah Basin Ozone Studies (UBOS), NOAA deployed its ground-based, scanning Tunable Optical Profiler for Aerosol and oZone (TOPAZ) lidar to document the vertical structure of ozone and aerosol backscatter from near the surface up to about 3 km above ground level (AGL). TOPAZ, along with a comprehensive set of chemistry and meteorological measurements, was situated in both years at the Horse Pool site at the northern edge of a large concentration of gas producing wells in the eastern part of the Uintah Basin. The 2012 study was characterized by unusually warm and snow-free condition and the TOPAZ lidar observed deep boundary layers (BL) and mostly well-mixed vertical ozone profiles at or slightly above tropospheric background levels. During UBOS 2013, winter weather conditions in the Uintah Basin were more typical with snow-covered ground and a persistent, shallow cold-pool layer. The TOPAZ lidar characterized with great temporal and spatial detail the evolution of multiple high-ozone episodes as well as cleanout events caused by the passage of synoptic-scale storm systems. Despite the snow cover, the TOPAZ observations show well-mixed afternoon ozone and aerosol profiles up to about 100 m AGL. After several days of pollutant buildup, BL ozone values reached 120-150 ppbv. Above the mixed layer, ozone values gradually decreased to tropospheric background values of around 50 ppbv throughout the several-hundred-meter-deep cold-pool layer and then stayed constant above that up to about 3 km AGL. During the ozone episodes, the lidar observations show no indication of either vertical or horizontal transport of high ozone levels to the surface, thus

  1. Vertical structure and optical properties of Titan's aerosols from radiance measurements made inside and outside the atmosphere

    NASA Astrophysics Data System (ADS)

    Doose, Lyn R.; Karkoschka, Erich; Tomasko, Martin G.; Anderson, Carrie M.

    2016-05-01

    Prompted by the detection of stratospheric cloud layers by Cassini's Composite Infrared Spectrometer (CIRS; see Anderson, C.M., Samuelson, R.E. [2011]. Icarus 212, 762-778), we have re-examined the observations made by the Descent Imager/Spectral Radiometer (DISR) in the atmosphere of Titan together with two constraints from measurements made outside the atmosphere. No evidence of thin layers (<1 km) in the DISR image data sets is seen beyond the three previously reported layers at 21 km, 11 km, and 7 km by Karkoschka and Tomasko (Karkoschka, E., Tomasko, M.G. [2009]. Icarus 199, 442-448). On the other hand, there is evidence of a thicker layer centered at about 55 km. A rise in radiance gradients in the Downward-Looking Visible Spectrometer (DLVS) data below 55 km indicates an increase in the volume extinction coefficient near this altitude. To fit the geometric albedo measured from outside the atmosphere the decrease in the single scattering albedo of Titan's aerosols at high altitudes, noted in earlier studies of DISR data, must continue to much higher altitudes. The altitude of Titan's limb as a function of wavelength requires that the scale height of the aerosols decrease with altitude from the 65 km value seen in the DISR observations below 140 km to the 45 km value at higher altitudes. We compared the variation of radiance with nadir angle observed in the DISR images to improve our aerosol model. Our new aerosol model fits the altitude and wavelength variations of the observations at small and intermediate nadir angles but not for large nadir angles, indicating an effect that is not reproduced by our radiative transfer model. The volume extinction profiles are modeled by continuous functions except near the enhancement level near 55 km altitude. The wavelength dependence of the extinction optical depth is similar to earlier results at wavelengths from 500 to 700 nm, but is smaller at shorter wavelengths and larger toward longer wavelengths. A Hapke

  2. Meridional gradients in aerosol vertical distribution over Indian Mainland: Observations and model simulations

    NASA Astrophysics Data System (ADS)

    Prijith, S. S.; Suresh Babu, S.; Lakshmi, N. B.; Satheesh, S. K.; Krishna Moorthy, K.

    2016-01-01

    Multi-year observations from the network of ground-based observatories (ARFINET), established under the project 'Aerosol Radiative Forcing over India' (ARFI) of Indian Space Research Organization and space-borne lidar 'Cloud Aerosol Lidar with Orthogonal Polarization' (CALIOP) along with simulations from the chemical transport model 'Goddard Chemistry Aerosol Radiation and Transport' (GOCART), are used to characterize the vertical distribution of atmospheric aerosols over the Indian landmass and its spatial structure. While the vertical distribution of aerosol extinction showed higher values close to the surface followed by a gradual decrease at increasing altitudes, a strong meridional increase is observed in the vertical spread of aerosols across the Indian region in all seasons. It emerges that the strong thermal convections cause deepening of the atmospheric boundary layer, which although reduces the aerosol concentration at lower altitudes, enhances the concentration at higher elevations by pumping up more aerosols from below and also helping the lofted particles to reach higher levels in the atmosphere. Aerosol depolarization ratios derived from CALIPSO as well as the GOCART simulations indicate the dominance of mineral dust aerosols during spring and summer and anthropogenic aerosols in winter. During summer monsoon, though heavy rainfall associated with the Indian monsoon removes large amounts of aerosols, the prevailing southwesterly winds advect more marine aerosols over to landmass (from the adjoining oceans) leading to increase in aerosol loading at lower altitudes than in spring. During spring and summer months, aerosol loading is found to be significant, even at altitudes as high as 4 km, and this is proposed to have significant impacts on the regional climate systems such as Indian monsoon.

  3. Decoration of vertical graphene with aerosol nanoparticles for gas sensing

    NASA Astrophysics Data System (ADS)

    Cui, Shumao; Guo, Xiaoru; Ren, Ren; Zhou, Guihua; Chen, Junhong

    2015-08-01

    A facile method was demonstrated to decorate aerosol Ag nanoparticles onto vertical graphene surfaces using a mini-arc plasma reactor. The vertical graphene was directly grown on a sensor electrode using a plasma-enhanced chemical vapor deposition (PECVD) method. The aerosol Ag nanoparticles were synthesized by a simple vapor condensation process using a mini-arc plasma source. Then, the nanoparticles were assembled on the surface of vertical graphene through the assistance of an electric field. Based on our observation, nonagglomerated Ag nanoparticles formed in the gas phase and were assembled onto vertical graphene sheets. Nanohybrids of Ag nanoparticle-decorated vertical graphene were characterized for ammonia gas detection at room temperature. The vertical graphene served as the conductance channel, and the conductance change upon exposure to ammonia was used as the sensing signal. The sensing results show that Ag nanoparticles significantly improve the sensitivity, response time, and recovery time of the sensor.

  4. Vertical Distribution of Dust and Water Ice Aerosols from CRISM Limb-geometry Observations

    NASA Technical Reports Server (NTRS)

    Smith, Michael Doyle; Wolff, Michael J.; Clancy, Todd; Kleinbohl, Armin; Murchie, Scott L.

    2013-01-01

    [1] Near-infrared spectra taken in a limb-viewing geometry by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on board the Mars Reconnaissance Orbiter provide a useful tool for probing atmospheric structure. Specifically, the observed radiance as a function of wavelength and height above the limb enables the vertical distribution of both dust and water ice aerosols to be retrieved. More than a dozen sets of CRISM limb observations have been taken so far providing pole-to-pole cross sections, spanning more than a full Martian year. Radiative transfer modeling is used to model the observations taking into account multiple scattering from aerosols and the spherical geometry of the limb observations. Both dust and water ice vertical profiles often show a significant vertical structure for nearly all seasons and latitudes that is not consistent with the well-mixed or Conrath-v assumptions that have often been used in the past for describing aerosol vertical profiles for retrieval and modeling purposes. Significant variations are seen in the retrieved vertical profiles of dust and water ice aerosol as a function of season. Dust typically extends to higher altitudes (approx. 40-50km) during the perihelion season than during the aphelion season (<20km), and the Hellas region consistently shows more dust mixed to higher altitudes than other locations. Detached water ice clouds are common, and water ice aerosols are observed to cap the dust layer in all seasons.

  5. Comparison of MADE3-simulated and observed aerosol distributions with a focus on aerosol vertical profiles

    NASA Astrophysics Data System (ADS)

    Kaiser, Christopher; Hendricks, Johannes; Righi, Mattia; Jöckel, Patrick

    2016-04-01

    The reliability of aerosol radiative forcing estimates from climate models depends on the accuracy of simulated global aerosol distribution and composition, as well as on the models' representation of the aerosol-cloud and aerosol-radiation interactions. To help improve on previous modeling studies, we recently developed the new aerosol microphysics submodel MADE3 that explicitly tracks particle mixing state in the Aitken, accumulation, and coarse mode size ranges. We implemented MADE3 into the global atmospheric chemistry general circulation model EMAC and evaluated it by comparison of simulated aerosol properties to observations. Compared properties include continental near-surface aerosol component concentrations and size distributions, continental and marine aerosol vertical profiles, and nearly global aerosol optical depth. Recent studies have shown the specific importance of aerosol vertical profiles for determination of the aerosol radiative forcing. Therefore, our focus here is on the evaluation of simulated vertical profiles. The observational data is taken from campaigns between 1990 and 2011 over the Pacific Ocean, over North and South America, and over Europe. The datasets include black carbon and total aerosol mass mixing ratios, as well as aerosol particle number concentrations. Compared to other models, EMAC with MADE3 yields good agreement with the observations - despite a general high bias of the simulated mass mixing ratio profiles. However, BC concentrations are generally overestimated by many models in the upper troposphere. With MADE3 in EMAC, we find better agreement of the simulated BC profiles with HIPPO data than the multi-model average of the models that took part in the AeroCom project. There is an interesting difference between the profiles from individual campaigns and more "climatological" datasets. For instance, compared to spatially and temporally localized campaigns, the model simulates a more continuous decline in both total

  6. Effect of aerosol vertical distribution on aerosol-radiation interaction: A theoretical prospect.

    PubMed

    Mishra, Amit Kumar; Koren, Ilan; Rudich, Yinon

    2015-10-01

    This study presents a theoretical investigation of the effect of the aerosol vertical distribution on the aerosol radiative effect (ARE). Four aerosol composition models (dust, polluted dust, pollution and pure scattering aerosols) with varying aerosol vertical profiles are incorporated into a radiative transfer model. The simulations show interesting spectral dependence of the ARE on the aerosol layer height. ARE increases with the aerosol layer height in the ultraviolet (UV: 0.25-0.42 μm) and thermal-infrared (TH-IR: 4.0-20.0 μm) regions, whereas it decreases in the visible-near infrared (VIS-NIR: 0.42-4.0 μm) region. Changes in the ARE with aerosol layer height are associated with different dominant processes for each spectral region. The combination of molecular (Rayleigh) scattering and aerosol absorption is the key process in the UV region, whereas aerosol (Mie) scattering and atmospheric gaseous absorption are key players in the VIS-NIR region. The longwave emission fluxes are controlled by the environmental temperature at the aerosol layer level. ARE shows maximum sensitivity to the aerosol layer height in the TH-IR region, followed by the UV and VIS-NIR regions. These changes are significant even in relatively low aerosol loading cases (aerosol optical depth ∼0.2-0.3). Dust aerosols are the most sensitive to altitude followed by polluted dust and pollution in all three different wavelength regions. Differences in the sensitivity of the aerosol type are explained by the relative strength of their spectral absorption/scattering properties. The role of surface reflectivity on the overall altitude dependency is shown to be important in the VIS-NIR and UV regions, whereas it is insensitive in the TH-IR region. Our results indicate that the vertical distribution of water vapor with respect to the aerosol layer is an important factor in the ARE estimations. Therefore, improved estimations of the water vapor profiles are needed for the further reduction in

  7. Effect of aerosol vertical distribution on aerosol-radiation interaction: A theoretical prospect.

    PubMed

    Mishra, Amit Kumar; Koren, Ilan; Rudich, Yinon

    2015-10-01

    This study presents a theoretical investigation of the effect of the aerosol vertical distribution on the aerosol radiative effect (ARE). Four aerosol composition models (dust, polluted dust, pollution and pure scattering aerosols) with varying aerosol vertical profiles are incorporated into a radiative transfer model. The simulations show interesting spectral dependence of the ARE on the aerosol layer height. ARE increases with the aerosol layer height in the ultraviolet (UV: 0.25-0.42 μm) and thermal-infrared (TH-IR: 4.0-20.0 μm) regions, whereas it decreases in the visible-near infrared (VIS-NIR: 0.42-4.0 μm) region. Changes in the ARE with aerosol layer height are associated with different dominant processes for each spectral region. The combination of molecular (Rayleigh) scattering and aerosol absorption is the key process in the UV region, whereas aerosol (Mie) scattering and atmospheric gaseous absorption are key players in the VIS-NIR region. The longwave emission fluxes are controlled by the environmental temperature at the aerosol layer level. ARE shows maximum sensitivity to the aerosol layer height in the TH-IR region, followed by the UV and VIS-NIR regions. These changes are significant even in relatively low aerosol loading cases (aerosol optical depth ∼0.2-0.3). Dust aerosols are the most sensitive to altitude followed by polluted dust and pollution in all three different wavelength regions. Differences in the sensitivity of the aerosol type are explained by the relative strength of their spectral absorption/scattering properties. The role of surface reflectivity on the overall altitude dependency is shown to be important in the VIS-NIR and UV regions, whereas it is insensitive in the TH-IR region. Our results indicate that the vertical distribution of water vapor with respect to the aerosol layer is an important factor in the ARE estimations. Therefore, improved estimations of the water vapor profiles are needed for the further reduction in

  8. Vertical profiles of atmospheric fluorescent aerosols observed by a mutil-channel lidar spectrometer system

    NASA Astrophysics Data System (ADS)

    Huang, Z.; Huang, J.; Zhou, T.; Sugimoto, N.; Bi, J.

    2015-12-01

    Zhongwei Huang1*, Jianping Huang1, Tian Zhou1, Nobuo Sugimoto2, Jianrong Bi1 and Jinsen Shi11Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou, China. 2Atmospheric Environment Division, National Institutes for Environmental Studies, Tsukuba, Japan Email: huangzhongwei@lzu.edu.cn Abstract Atmospheric aerosols have a significant impact on regional and globe climate. The challenge in quantifying aerosol direct radiative forcing and aerosol-cloud interactions arises from large spatial and temporal heterogeneity of aerosol concentrations, compositions, sizes, shape and optical properties (IPCC, 2007). Lidar offers some remarkable advantages for determining the vertical structure of atmospheric aerosols and their related optical properties. To investigate the characterization of atmospheric aerosols (especially bioaerosols) with high spatial and temporal resolution, we developed a Raman/fluorescence/polarization lidar system employed a multi-channel spectrometer, with capabilities of providing measurements of Raman scattering and laser-induced fluorescence excitation at 355 nm from atmospheric aerosols. Meanwhile, the lidar system operated polarization measurements both at 355nm and 532nm wavelengths, aiming to obtain more information of aerosols. It employs a high power pulsed laser and a received telescope with 350mm diameter. The receiver could simultaneously detect a wide fluorescent spectrum about 178 nm with spectral resolution 5.7 nm, mainly including an F/3.7 Crossed Czerny-Turner spectrograph, a grating (1200 gr/mm) and a PMT array with 32 photocathode elements. Vertical structure of fluorescent aerosols in the atmosphere was observed by the developed lidar system at four sites across northwest China, during 2014 spring field observation that conducted by Lanzhou University. It has been proved that the developed lidar could detect the fluorescent aerosols with high temporal and

  9. LIDAR Measurements of the Vertical Distribution of Aerosol Optical and Physical Properties over Central Asia

    EPA Science Inventory

    The vertical structure of aerosol optical and physical properties was measured by Lidar in Eastern Kyrgyzstan, Central Asia, from June 2008 to May 2009. Lidar measurements were supplemented with surface-based measurements of PM2.5 and PM10 mass and chemical ...

  10. Global profiles of the direct aerosol effect using vertically resolved aerosol data

    NASA Astrophysics Data System (ADS)

    Korras Carraca, Marios Bruno; Pappas, Vasilios; Matsoukas, Christos; Hatzianastassiou, Nikolaos; Vardavas, Ilias

    2014-05-01

    Atmospheric aerosols, both natural and anthropogenic, can cause climate change through their direct, indirect, and semi-direct effects on the radiative energy budget of the Earth-atmosphere system. In general, aerosols cause cooling of the surface and the planet, while they warm the atmosphere due to scattering and absorption of incoming solar radiation. The importance of vertically resolved direct radiative effect (DRE) and heating/cooling effects of aerosols is strong, while large uncertainties still lie with their magnitudes. In order to be able to quantify them throughout the atmosphere, a detailed vertical profile of the aerosol effect is required. Such data were made available recently by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite. CALIOP is the first polarization lidar to fly in space and has been acquiring unique data on aerosols and clouds since June 2006. The aim of this study is to investigate both the vertically resolved geographic and seasonal variation of the DRE due to aerosols. The vertical profile of DRE under all-sky and clear-sky conditions is computed using the deterministic spectral radiative transfer model FORTH. From the DRE, the effect on atmospheric heating/cooling rate profiles due to aerosols can also be derived. We use CALIOP Level 2-Version 3 Layer aerosol optical depth data as input to our radiation transfer model, for a period of 3 complete years (2007-2009). These data are provided on a 5 km horizontal resolution and in up to 8 vertical layers and have been regridded on our model horizontal and vertical resolutions. We use cloud data from the International Satellite Cloud Climatology Project (ISCCP), while the aerosol asymmetry factor and single scattering albedo are taken from the Global Aerosol Data Set (GADS). The model computations are performed on a monthly, 2.5°× 2.5° resolution on global scale, at 40

  11. Comparison of Aerosol Classification From Airborne High Spectral Resolution Lidar and the CALIPSO Vertical Feature Mask

    NASA Technical Reports Server (NTRS)

    Burton, Sharon P.; Ferrare, Rich A.; Omar, Ali H.; Vaughan, Mark A.; Rogers, Raymond R.; Hostetler, Chris a.; Hair, Johnathan W.; Obland, Michael D.; Butler, Carolyn F.; Cook, Anthony L.; Harper, David B.

    2012-01-01

    Knowledge of aerosol composition and vertical distribution is crucial for assessing the impact of aerosols on climate. In addition, aerosol classification is a key input to CALIOP aerosol retrievals, since CALIOP requires an inference of the lidar ratio in order to estimate the effects of aerosol extinction and backscattering. In contrast, the NASA airborne HSRL-1 directly measures both aerosol extinction and backscatter, and therefore the lidar ratio (extinction-to-backscatter ratio). Four aerosol intensive properties from HSRL-1 are combined to infer aerosol type. Aerosol classification results from HSRL-1 are used here to validate the CALIOP aerosol type inferences.

  12. Aromatic Structure in Simulates Titan Aerosol

    NASA Technical Reports Server (NTRS)

    Trainer, Melissa G.; Loeffler, M. J.; Anderson, C. M.; Hudson, R. L.; Samuelson, R. E.; Moore, M. A.

    2011-01-01

    Observations of Titan by the Cassini Composite Infrared Spectrometer (CIRS) between 560 and 20 per centimeter (approximately 18 to 500 micrometers) have been used to infer the vertical variations of Titan's ice abundances, as well as those of the aerosol from the surface to an altitude of 300 km [1]. The aerosol has a broad emission feature centered approximately at 140 per centimeter (71 micrometers). As seen in Figure 1, this feature cannot be reproduced using currently available optical constants from laboratory-generated Titan aerosol analogs [2]. The far-IR is uniquely qualified for investigating low-energy vibrational motions within the lattice structures of COITIDlex aerosol. The feature observed by CIRS is broad, and does not likely arise from individual molecules, but rather is representative of the skeletal movements of macromolecules. Since Cassini's arrival at Titan, benzene (C6H6) has been detected in the atmosphere at ppm levels as well as ions that may be polycyclic aromatic hydrocarbons (PAHs) [3]. We speculate that the feature may be a blended composite that can be identified with low-energy vibrations of two-dimensional lattice structures of large molecules, such as PAHs or nitrogenated aromatics. Such structures do not dominate the composition of analog materials generated from CH4 and N2 irradiation. We are performing studies forming aerosol analog via UV irradiation of aromatic precursors - specifically C6H6 - to understand how the unique chemical architecture of the products will influence the observable aerosol characteristics. The optical and chemical properties of the aromatic analog will be compared to those formed from CH4/N2 mixtures, with a focus on the as-yet unidentified far-IR absorbance feature. Preliminary results indicate that the photochemically-formed aromatic aerosol has distinct chemical composition, and may incorporate nitrogen either into the ring structure or adjoined chemical groups. These compositional differences are

  13. Vertical profiles of aerosol optical properties and the solar heating rate estimated by combining sky radiometer and lidar measurements

    NASA Astrophysics Data System (ADS)

    Kudo, Rei; Nishizawa, Tomoaki; Aoyagi, Toshinori

    2016-07-01

    The SKYLIDAR algorithm was developed to estimate vertical profiles of aerosol optical properties from sky radiometer (SKYNET) and lidar (AD-Net) measurements. The solar heating rate was also estimated from the SKYLIDAR retrievals. The algorithm consists of two retrieval steps: (1) columnar properties are retrieved from the sky radiometer measurements and the vertically mean depolarization ratio obtained from the lidar measurements and (2) vertical profiles are retrieved from the lidar measurements and the results of the first step. The derived parameters are the vertical profiles of the size distribution, refractive index (real and imaginary parts), extinction coefficient, single-scattering albedo, and asymmetry factor. Sensitivity tests were conducted by applying the SKYLIDAR algorithm to the simulated sky radiometer and lidar data for vertical profiles of three different aerosols, continental average, transported dust, and pollution aerosols. The vertical profiles of the size distribution, extinction coefficient, and asymmetry factor were well estimated in all cases. The vertical profiles of the refractive index and single-scattering albedo of transported dust, but not those of transported pollution aerosol, were well estimated. To demonstrate the performance and validity of the SKYLIDAR algorithm, we applied the SKYLIDAR algorithm to the actual measurements at Tsukuba, Japan. The detailed vertical structures of the aerosol optical properties and solar heating rate of transported dust and smoke were investigated. Examination of the relationship between the solar heating rate and the aerosol optical properties showed that the vertical profile of the asymmetry factor played an important role in creating vertical variation in the solar heating rate. We then compared the columnar optical properties retrieved with the SKYLIDAR algorithm to those produced with the more established scheme SKYRAD.PACK, and the surface solar irradiance calculated from the SKYLIDAR

  14. Parameter sensitivity study of Arctic aerosol vertical distribution in CAM5

    NASA Astrophysics Data System (ADS)

    Jiao, C.; Flanner, M.

    2015-12-01

    Arctic surface temperature response to light-absorbing aerosols (black carbon, brown carbon and dust) depends strongly on their vertical distributions. Improving model simulations of three dimensional aerosol fields in the remote Arctic region will therefore lead to improved projections of the climate change caused by aerosol emissions. In this study, we investigate how different physical parameterizations in the Community Atmosphere Model version 5 (CAM5) influence the simulated vertical distribution of Arctic aerosols. We design experiments to test the sensitivity of the simulated aerosol fields to perturbations of selected aerosol process-related parameters in the Modal Aerosol Module with seven lognormal modes (MAM7), such as those govern aerosol aging, in-cloud and below-cloud scavenging, aerosol hygroscopicity and so on. The simulations are compared with observed aerosol vertical distributions and total optical depth to assess model performance and quantify uncertainties associated with these model parameterizations. Observations applied here include Arctic aircraft measurements of black carbon and sulfate vertical profiles, along with Aerosol Robotic Network (AERONET) optical depth measurements. We also assess the utility of using High Spectral Resolution Lidar (HSRL) measurements from the ARM Barrow site to infer vertical profiles of aerosol extinction. The sensitivity study explored here will provide guidance for optimizing global aerosol simulations.

  15. Seasonal variation of vertical distribution of aerosol single scattering albedo over Indian sub-continent: RAWEX aircraft observations

    NASA Astrophysics Data System (ADS)

    Suresh Babu, S.; Nair, Vijayakumar S.; Gogoi, Mukunda M.; Krishna Moorthy, K.

    2016-01-01

    To characterize the vertical distribution of aerosols and its seasonality (especially the single scattering albedo, SSA) extensive profiling of aerosol scattering and absorption coefficients have been carried out using an instrumented aircraft from seven base stations spread across the Indian mainland during winter 2012 and spring/pre-monsoon 2013 under the Regional Aerosol Warming Experiment (RAWEX). Spatial variation of the vertical profiles of the asymmetry parameter, the wavelength exponent of the absorption coefficient and the single scattering albedo, derived from the measurements, are used to infer the source characteristics of winter and pre-monsoon aerosols as well as the seasonality of free tropospheric aerosols. The relatively high value of the wavelength exponent of absorption coefficient over most of the regions indicates the contribution from biomass burning and dust aerosols up to lower free tropospheric altitudes. A clear enhancement in aerosol loading and its absorbing nature is seen at lower free troposphere levels (above the planetary boundary layer) over the entire mainland during spring/pre-monsoon season compared to winter, whereas concentration of aerosols within the boundary layer showed a decrease from winter to spring. This could have significant implications on the aerosol heating structure over the Indian region and hence the regional climate.

  16. Comparison of Aerosol Classification from Airborne High Spectral Resolution Lidar and the CALIPSO Vertical Feature Mask

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Ferrare, R. A.; Omar, A. H.; Hostetler, C. A.; Hair, J. W.; Rogers, R.; Obland, M. D.; Butler, C. F.; Cook, A. L.; Harper, D. B.

    2012-12-01

    The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL-1) on the NASA B200 aircraft has acquired large datasets of aerosol extinction (532nm), backscatter (532 and 1064nm), and depolarization (532 and 1064nm) profiles during 349 science flights in 19 field missions across North America since 2006. The extinction-to-backscatter ratio ("lidar ratio"), aerosol depolarization ratios, and backscatter color ratio measurements from HSRL-1 are scale-invariant parameters that depend on aerosol type but not concentration. These four aerosol intensive parameters are combined to qualitatively classify HSRL aerosol measurements into eight separate composition types. The classification methodology uses models formed from "training cases" with known aerosol type. The remaining measurements are then compared with these models using the Mahalanobis distance. Aerosol products from the CALIPSO satellite include aerosol type information as well, which is used as input to the CALIPSO aerosol retrieval. CALIPSO aerosol types are inferred using a mix of aerosol loading-dependent parameters, estimated aerosol depolarization, and location, altitude, and surface type information. The HSRL instrument flies beneath the CALIPSO satellite orbit track, presenting the opportunity for comparisons between the HSRL aerosol typing and the CALIPSO Vertical Feature Mask Aerosol Subtype product, giving insight into the performance of the CALIPSO aerosol type algorithm. We find that the aerosol classification from the two instruments frequently agree for marine aerosols and pure dust, and somewhat less frequently for pollution and smoke. In addition, the comparison suggests that the CALIPSO polluted dust type is overly inclusive, encompassing cases of dust combined with marine aerosol as well as cases without much evidence of dust. Qualitative classification of aerosol type combined with quantitative profile measurements of aerosol backscatter and extinction has many useful

  17. Lidar Measurements of the Vertical Distribution of Aerosol Optical and Physical Properties over Central Asia

    DOE PAGES

    Chen, Boris B.; Sverdlik, Leonid G.; Imashev, Sanjar A.; Solomon, Paul A.; Lantz, Jeffrey; Schauer, James J.; Shafer, Martin M.; Artamonova, Maria S.; Carmichael, Gregory R.

    2013-01-01

    The vertical structure of aerosol optical and physical properties was measured by Lidar in Eastern Kyrgyzstan, Central Asia, from June 2008 to May 2009. Lidar measurements were supplemented with surface-based measurements of PM 2.5 and PM 10 mass and chemical composition in both size fractions. Dust transported into the region is common, being detected 33% of the time. The maximum frequency occurred in the spring of 2009. Dust transported to Central Asia comes from regional sources, for example, Taklimakan desert and Aral Sea basin, and from long-range transport, for example, deserts of Arabia, Northeast Africa, Iran, and Pakistan. Regionalmore » sources are characterized by pollution transport with maximum values of coarse particles within the planetary boundary layer, aerosol optical thickness, extinction coefficient, integral coefficient of aerosol backscatter, and minimum values of the Ångström exponent. Pollution associated with air masses transported over long distances has different characteristics during autumn, winter, and spring. During winter, dust emissions were low resulting in high values of the Ångström exponent (about 0.51) and the fine particle mass fraction (64%). Dust storms were more frequent during spring with an increase in coarse dust particles in comparison to winter. The aerosol vertical profiles can be used to lower uncertainty in estimating radiative forcing.« less

  18. The Importance of the Vertical Location of Aerosol Layers on Convective Storms

    NASA Astrophysics Data System (ADS)

    van den Heever, Susan; Grant, Leah

    2014-05-01

    Enhanced aerosol concentrations appear to influence a number of the aspects of convective storms including the strength of the convective updraft, the intensity of the cold pool, and the microphysical and radiative characteristics of the convective anvil. However, in order for such influences to occur, aerosols need to be effectively ingested by the storm system of interest. The vertical location of an aerosol layer impacting a convective storm may influence how effectively aerosol are ingested by the storm system, and hence the degree to which the ingested aerosol subsequently influence storm microphysical and radiative processes. Furthermore, if the aerosol species impacting the storm are effective at absorbing solar radiation, heating within the aerosol layer enhances atmospheric stability, the level of which will be dictated by where the aerosol layer is located. Enhanced static stability may have negative impacts on the initial development of the convection of interest. Convective storms developing within environments of the same aerosol optical depth may therefore respond differently to aerosol indirect forcing by virtue of where the aerosol layer is vertically located. In this talk, the results of various high-resolution, cloud-resolving simulations will be presented, in which the sensitivity to the vertical location of the aerosol source on the convective development, aerosol ingestion efficiency, and subsequent microphysical and radiative properties are investigated. Microphysical budgets and storm trajectories will form an integral part of the analysis.

  19. Deriving Vertical Profiles of Aerosol Sizes from TES

    NASA Astrophysics Data System (ADS)

    Wolff, M. J.; Clancy, R. T.; Smith, M. D.; McConnochie, T. H.; Flittner, D. E.; Fouchet, T.

    2011-12-01

    Vertical variations in aerosol particle sizes can have a dramatic effect in their net impact on the state and evolution of the Martian atmosphere. Recent analyses of data from the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) and the Thermal Emission Spectrometer (TES) instruments offer some long overdue progress in constraining this aspect of aerosols. However, significantly more work remains to be done along these lines in order to better constrain and inform modern dynamical simulations of the Martian atmosphere. Thus, the primary goal of our work is to perform retrievals of particle size as a function of altitude for both dust and water ice aerosols. The choice of the TES dataset, with pole-to-pole coverage over a period of nearly three martian years, provides the crucial systematic temporal and spatial sampling. Additional leverage on the particle size will be obtained by using both solarband bolometry and infrared (IR) spectroscopy. Our presentation will include: 1) A summary of our limb radiative transfer comparison/validation exercises which include Monte Carlo, Gauss-Seidel, and discrete-ordinate algorithms (including the plane-parallel source function approximation). 2) The initial results of the application of our particle size retrieval scheme to the TES observations of the 2001 planet encircling dust event. 3) A few test applications to the Mars Climate Sounder (MCS) radiance profiles (enabled by the recent solarband radiometric calibration by Bandfield and collaborators). 4) Our plans for additional retrievals (aphelion cloud season, lower optical depth locations and seasons, etc.) and the distribution of the derived profiles.

  20. Vertical profiling of aerosol hygroscopic properties in the planetary boundary layer during the PEGASOS campaigns

    NASA Astrophysics Data System (ADS)

    Rosati, Bernadette; Gysel, Martin; Rubach, Florian; Mentel, Thomas F.; Goger, Brigitta; Poulain, Laurent; Schlag, Patrick; Miettinen, Pasi; Pajunoja, Aki; Virtanen, Annele; Klein Baltink, Henk; Bas Henzing, J. S.; Größ, Johannes; Gobbi, Gian Paolo; Wiedensohler, Alfred; Kiendler-Scharr, Astrid; Decesari, Stefano; Facchini, Maria Cristina; Weingartner, Ernest; Baltensperger, Urs

    2016-06-01

    Vertical profiles of the aerosol particles hygroscopic properties, their mixing state as well as chemical composition were measured above northern Italy and the Netherlands. An aerosol mass spectrometer (AMS; for chemical composition) and a white-light humidified optical particle spectrometer (WHOPS; for hygroscopic growth) were deployed on a Zeppelin NT airship within the PEGASOS project. This allowed one to investigate the development of the different layers within the planetary boundary layer (PBL), providing a unique in situ data set for airborne aerosol particles properties in the first kilometre of the atmosphere. Profiles measured during the morning hours on 20 June 2012 in the Po Valley, Italy, showed an increased nitrate fraction at ˜ 100 m above ground level (a.g.l.) coupled with enhanced hygroscopic growth compared to ˜ 700 m a. g. l. This result was derived from both measurements of the aerosol composition and direct measurements of the hygroscopicity, yielding hygroscopicity parameters (κ) of 0.34 ± 0.12 and 0.19 ± 0.07 for 500 nm particles, at ˜ 100 and ˜ 700 m a. g. l., respectively. The difference is attributed to the structure of the PBL at this time of day which featured several independent sub-layers with different types of aerosols. Later in the day the vertical structures disappeared due to the mixing of the layers and similar aerosol particle properties were found at all probed altitudes (mean κ ≈ 0.18 ± 0.07). The aerosol properties observed at the lowest flight level (100 m a. g. l.) were consistent with parallel measurements at a ground site, both in the morning and afternoon. Overall, the aerosol particles were found to be externally mixed, with a prevailing hygroscopic fraction. The flights near Cabauw in the Netherlands in the fully mixed PBL did not feature altitude-dependent characteristics. Particles were also externally mixed and had an even larger hygroscopic fraction compared to the results in Italy. The mean κ from

  1. Vertical Distribution of Aerosols and Water Vapor Using CRISM Limb Observations

    NASA Astrophysics Data System (ADS)

    Smith, M. D.; Wolff, M. J.; Clancy, R. T.; CRISM Science; Operations Teams

    2011-12-01

    Near-infrared spectra taken in a limb-viewing geometry by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on-board the Mars Reconnaissance Orbiter (MRO) provide a useful tool for probing atmospheric structure. Specifically, the observed radiance as a function of wavelength and height above the limb allows the vertical distribution of both dust and ice aerosols to be retrieved. These data serve as an important supplement to the aerosol profiling provided by the MRO/MCS instrument allowing independent validation and giving additional information on particle physical and scattering properties through multi-wavelength studies. A total of at least ten CRISM limb observations have been taken so far covering a full Martian year. Each set of limb observations nominally contains about four dozen scans across the limb giving pole-to-pole coverage for two orbits at roughly 100 and 290 W longitude over the Tharsis and Syrtis/Hellas regions, respectively. At each longitude, limb scans are spaced roughly 10 degrees apart in latitude, with a vertical spatial resolution on the limb of roughly 800 m. Radiative transfer modeling is used to model the observations. We compute synthetic CRISM limb spectra using a discrete-ordinates radiative transfer code that accounts for multiple scattering from aerosols and accounts for spherical geometry of the limb observations by integrating the source functions along curved paths in that coordinate system. Retrieved are 14-point vertical profiles for dust and water ice aerosols with resolution of 0.4 scale heights between one and six scale heights above the surface. After the aerosol retrieval is completed, the abundances of CO2 (or surface pressure) and H2O gas are retrieved by matching the depth of absorption bands at 2000 nm for carbon dioxide and at 2600 nm for water vapor. In addition to the column abundance of water vapor, limited information on its vertical structure can also be retrieved depending on the signal available

  2. Vertical profiles of cloud condensation nuclei, aerosol hygroscopicity, water uptake, and scattering across the United States

    NASA Astrophysics Data System (ADS)

    Lin, J. J.; Bougiatioti, A.; Nenes, A.; Anderson, B. E.; Beyersdorf, A. J.; Brock, C. A.; Gordon, T. D.; Lack, D.; Law, D. C.; Liao, J.; Middlebrook, A. M.; Richardson, M.; Thornhill, K. L., II; Winstead, E.; Wagner, N. L.; Welti, A.; Ziemba, L. D.

    2014-12-01

    The evolutions of vertical distributions of aerosol chemical, microphysical, hygroscopic, and optical properties present fundamental challenges to the understanding of ground-level air quality and radiative transfer, and few datasets exist to date for evaluation of atmospheric models. Data collected from recent NASA and NOAA field campaigns in the California Central Valley (DISCOVER-AQ), southeast United States (SENEX, SEAC4RS) and Texas (DISCOVER-AQ) allow for a unique opportunity to constrain vertical profiles of climate-relevant aerosol properties. This work presents in-situ aircraft measurements of cloud condensation nuclei (CCN) concentration and derivations of aerosol hygroscopicity, water uptake, and light scattering. Aerosol hygroscopicity is derived from CCN and aerosol measurements. Inorganic water uptake is calculated from aerosol composition using ISORROPIA, a chemical thermodynamic model, while organic water uptake is calculated from organic hygroscopicity. Aerosol scattering closure is performed between scattering from water uptake calculations and in-situ scattering measurements.

  3. Fabrication of vertical nanowire resonators for aerosol exposure assessment

    NASA Astrophysics Data System (ADS)

    Merzsch, Stephan; Wasisto, Hutomo Suryo; Stranz, Andrej; Hinze, Peter; Weimann, Thomas; Peiner, Erwin; Waag, Andreas

    2013-05-01

    Vertical silicon nanowire (SiNW) resonators are designed and fabricated in order to assess exposure to aerosol nanoparticles (NPs). To realize SiNW arrays, nanolithography and inductively coupled plasma (ICP) deep reactive ion etching (DRIE) at cryogenic temperature are utilized in a top-down fabrication of SiNW arrays which have high aspect ratios (i.e., up to 34). For nanolithography process, a resist film thickness of 350 nm is applied in a vacuum contact mode to serve as a mask. A pattern including various diameters and distances for creating pillars is used (i.e., 400 nm up to 5 μm). In dry etching process, the etch rate is set high of 1.5 μm/min to avoid underetching. The etch profiles of Si wires can be controlled aiming to have either perpendicularly, negatively or positively profiled sidewalls by adjusting the etching parameters (e.g., temperature and oxygen content). Moreover, to further miniaturize the wire, multiple sacrificial thermal oxidations and subsequent oxide stripping are used yielding SiNW arrays of 650 nm in diameter and 40 μm in length. In the resonant frequency test, a piezoelectric shear actuator is integrated with the SiNWs inside a scanning electron microscope (SEM) chamber. The observation of the SiNW deflections are performed and viewed from the topside of the SiNWs to reduce the measurement redundancy. Having a high deflection of ~10 μm during its resonant frequency of 452 kHz and a low mass of 31 pg, the proposed SiNW is potential for assisting the development of a portable aerosol resonant sensor.

  4. ACTRIS aerosol vertical profile data and observations: potentiality and first examples of integrated studies with models

    NASA Astrophysics Data System (ADS)

    Mona, Lucia; Benedetti, Angela; D'Amico, Giuseppe; Myhre, Cathrine Lund; Schulz, Michael; Wandinger, Ulla; Laj, Paolo; Pappalardo, Gelsomina

    2016-04-01

    The ACTRIS-2 project, funded by Horizon 2020, addresses the scope of integrating state-of-the-art European ground-based stations for long term observations of aerosols, clouds and short lived gases, capitalizing on the work of FP7-ACTRIS. It aims at achieving the construction of a user-oriented RI, unique in the EU-RI landscape for providing 4-D integrated high-quality data from near-surface to high altitude (vertical profiles and total-column) which are relevant to climate and air-quality research. ACTRIS-2 develops and implements, in a large network of stations in Europe and beyond, observational protocols that permit the harmonization of collected data and their dissemination. ACTRIS secures provision and dissemination of a unique set of data and data-products that would not otherwise be available with the same level of quality and standardization. This results from a 10-year plus effort in constructing a research infrastructure capable of responding to community needs and requirements, and has been engaged since the start of the FP5 EU commission program. ACTRIS ensures compliance with reporting requirements (timing, format, traceability) defined by the major global observing networks. EARLINET (European Aerosol research Lidar NETwork), the aerosol vertical profiling component of ACTRIS, is providing since May 2000 vertical profiles of aerosol extinction and backscatter over Europe. A new structure of the EARLINET database has been designed in a more user oriented approach reporting new data products which are more effective for specific uses of different communities. In particular, a new era is starting with the Copernicus program during which the aerosol vertical profiling capability will be fundamental for assimilation and validation purposes. The new data products have been designed thanks to a strong link with EARLINET data users, first of all modeling and satellite communities, established since the beginning of EARLINET and re-enforced within ACTRIS2

  5. Vertical Profiles of Aerosol Volume from High Spectral Resolution Infrared Transmission Measurements: Results

    NASA Technical Reports Server (NTRS)

    Eldering, Annmarie; Kahn, Brian H.; Mills, Franklin P.; Irion, Fredrick W.; Steele, Helen M.; Gunson, Michael R.

    2004-01-01

    The high-resolution infrared absorption spectra of the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment are utilized to derive vertical profiles of sulfate aerosol volume density and extinction coefficient. Following the eruption of Mt. Pinatubo in June 1991, the ATMOS spectra obtained on three Space Shuttle missions (1992, 1993, and 1994) provide a unique opportunity to study the global stratospheric sulfate aerosol layer shortly after a major volcanic eruption and periodically during the decay phase. Synthetic sulfate aerosol spectra are fit to the observed spectra, and a global fitting inversion routine is used to derive vertical profiles of sulfate aerosol volume density. Vertical profiles of sulfate aerosol volume density for the three missions over portions of the globe are presented, with the peak in aerosol volume density occurring from as low as 10 km (polar latitudes) to as high as 20 km (subtropical latitudes). Derived aerosol volume density is as high as 2-3.5 (mu)m(exp 3) per cubic centimeter +/-10% in 1992, decreasing to 0.2-0.5 (mu)m(exp 3) per cubic centimeter +/-20% in 1994, in agreement with other experiments. Vertical extinction profiles derived from ATMOS are compared with profiles from Improved Stratospheric And Mesospheric Sounder (ISAMS) and Cryogenic Limb Array Etalon Spectrometer (CLAES) that coincide in space and time and show good general agreement. The uncertainty of the ATMOS vertical profiles is similar to CLAES and consistently smaller than ISAMS at similar altitudes.

  6. Radiosonde aerosol counter for vertical profiling of atmospheric dust layers

    NASA Astrophysics Data System (ADS)

    Ulanowski, Z.; Hirst, E.; Kaye, P. H.; Harrison, R. G.; Nicoll, K. A.; Rogers, G.

    2010-05-01

    A low-cost, miniature aerosol particle counter has been developed, intended for use with balloon-borne meteorological radiosondes. It is particularly suitable for airborne mineral dust measurements. Ambient air is drawn into the counter using a diaphragm pump at a rate of 0.5 litre per minute. The counter detects particles in the airstream using a diode laser and a photodiode. Output from the photodiode is digitised into 5 size bins, with minimum particle diameters equivalent to 0.6, 1.4, 2.6, 5.4 and 10.6 micrometers. The counter is interfaced to a Vaisala RS92 radiosonde, which transmits data from the counter together with meteorological parameters and GPS-derived position to a ground based receiver at 1 Hz rate. Statistically significant particle size distributions can be obtained once a second for number concentrations down to about 100,000 particle per litre (within the measured size range), or correspondingly less at lower temporal resolutions. At the same time, the counter is capable of measuring dust number concentrations exceeding a million per litre without incurring significant errors. Soundings during the DREAME campaign in Kuwait (Ulanowski et al. EGU 2010, AS4.7) and on Cape Verde Islands (Nicoll et al. EGU 2010, AS4.7) provided dust concentration profiles with a typical vertical resolution of 4 m. Comparisons with integrated dust column size distribution measurements from AERONET sun photometers showed good agreement in two out of three cases where near-simultaneous retrievals were available. Optical thickness calculations based on the size distributions measured in Kuwait, with the assumption that the dust particles were prolate spheroids, agreed with the AERONET optical thickness at 675 nm to within 15%.

  7. Measurements of Atmospheric Aerosol Vertical Distributions above Svalbard, Norway using Unmanned Aerial Systems (UAS)

    NASA Astrophysics Data System (ADS)

    Bates, T. S.; Johnson, J. E.; Stalin, S.; Telg, H.; Murphy, D. M.; Burkhart, J. F.; Quinn, P.; Storvold, R.

    2015-12-01

    Atmospheric aerosol vertical distributions were measured above Svalbard, Norway in April 2015 to investigate the processes controlling aerosol concentrations and radiative effects. The aerosol payload was flown in a NOAA/PMEL MANTA Unmanned Aerial System (UAS) on 9 flights totaling 19 flight hours. Measurements were made of particle number concentration and aerosol light absorption at three wavelengths, similar to those conducted in April 2011 (Bates et al., Atmos. Meas. Tech., 6, 2115-2120, 2013). A filter sample was collected on each flight for analyses of trace elements. Additional measurements in the aerosol payload in 2015 included aerosol size distributions obtained using a Printed Optical Particle Spectrometer (POPS) and aerosol optical depth obtained using a four wavelength miniature Scanning Aerosol Sun Photometer (miniSASP). The data show most of the column aerosol mass and resulting optical depth in the boundary layer but frequent aerosol layers aloft with high particle number concentration (2000 cm-3) and enhanced aerosol light absorption (1 Mm-1). Transport of these aerosol layers was assessed using FLEXPART particle dispersion models. The data contribute to an assessment of sources of BC to the Arctic and potential climate impacts.

  8. Vertical distribution of aerosol optical properties based on aircraft measurements over the Loess Plateau in China.

    PubMed

    Li, Junxia; Liu, Xingang; Yuan, Liang; Yin, Yan; Li, Zhanqing; Li, Peiren; Ren, Gang; Jin, Lijun; Li, Runjun; Dong, Zipeng; Li, Yiyu; Yang, Junmei

    2015-08-01

    Vertical distributions of aerosol optical properties based on aircraft measurements over the Loess Plateau were measured for the first time during a summertime aircraft campaign, 2013 in Shanxi, China. Data from four flights were analyzed. The vertical distributions of aerosol optical properties including aerosol scattering coefficients (σsc), absorption coefficients (σab), Angström exponent (α), single scattering albedo (ω), backscattering ratio (βsc), aerosol mass scattering proficiency (Qsc) and aerosol surface scattering proficiency (Qsc(')) were obtained. The mean statistical values of σsc were 77.45 Mm(-1) (at 450 nm), 50.72 Mm(-1) (at 550n m), and 32.02 Mm(-1) (at 700 nm). The mean value of σab was 7.62 Mm(-1) (at 550 nm). The mean values of α, βsc and ω were 1.93, 0.15, and 0.91, respectively. Aerosol concentration decreased with altitude. Most effective diameters (ED) of aerosols were less than 0.8 μm. The vertical profiles of σsc,, α, βsc, Qsc and Qsc(') showed that the aerosol scattering properties at lower levels contributed the most to the total aerosol radiative forcing. Both α and βsc had relatively large values, suggesting that most aerosols in the observational region were small particles. The mean values of σsc, α, βsc, Qsc, Qsc('), σab and ω at different height ranges showed that most of the parameters decreased with altitude. The forty-eight hour backward trajectories of air masses during the observation days indicated that the majority of aerosols in the lower level contributed the most to the total aerosol loading, and most of these particles originated from local or regional pollution emissions.

  9. Impact of aerosol vertical distribution on aerosol direct radiative effect and heating rate in the Mediterranean region

    NASA Astrophysics Data System (ADS)

    Pappas, Vasileios; Hatzianastassiou, Nikolaos; Matsoukas, Christos; Koras Carracca, Mario; Kinne, Stefan; Vardavas, Ilias

    2015-04-01

    It is now well-established that aerosols cause an overall cooling effect at the surface and a warming effect within the atmosphere. At the top of the atmosphere (TOA), both positive and negative forcing can be found, depending on a number of other factors, such as surface albedo and relative position of clouds and aerosols. Whilst aerosol surface cooling is important due to its relation with surface temperature and other bio-environmental reasons, atmospheric heating is of special interest as well having significant impacts on atmospheric dynamics, such as formation of clouds and subsequent precipitation. The actual position of aerosols and their altitude relative to clouds is of major importance as certain types of aerosol, such as black carbon (BC) above clouds can have a significant impact on planetary albedo. The vertical distribution of aerosols and clouds has recently drawn the attention of the aerosol community, because partially can account for the differences between simulated aerosol radiative forcing with various models, and therefore decrease the level of our uncertainty regarding aerosol forcing, which is one of our priorities set by IPCC. The vertical profiles of aerosol optical and physical properties have been studied by various research groups around the world, following different methodologies and using various indices in order to present the impact of aerosols on radiation on different altitudes above the surface. However, there is still variability between the published results as to the actual effect of aerosols on shortwave radiation and on heating rate within the atmosphere. This study uses vertical information on aerosols from the Max Planck Aerosol Climatology (MAC-v1) global dataset, which is a combination of model output with quality ground-based measurements, in order to provide useful insight into the vertical profile of atmospheric heating for the Mediterranean region. MAC-v1 and the science behind this aerosol dataset have already

  10. Characterizing the Vertical Distribution of Aerosols Over the ARM SGP Site

    SciTech Connect

    Richard Ferrare, Connor Flynn, David Turner

    2009-05-05

    This project focused on: 1) evaluating the performance of the DOE ARM SGP Raman lidar system in measuring profiles of water vapor and aerosols, and 2) the use of the Raman lidar measurements of aerosol and water vapor profiles for assessing the vertical distribution of aerosols and water vapor simulated by global transport models and examining diurnal variability of aerosols and water vapor. The highest aerosol extinction was generally observed close to the surface during the nighttime just prior to sunrise. The high values of aerosol extinction are most likely associated with increased scattering by hygroscopic aerosols, since the corresponding average relative humidity values were above 70%. After sunrise, relative humidity and aerosol extinction below 500 m decreased with the growth in the daytime convective boundary layer. The largest aerosol extinction for altitudes above 1 km occurred during the early afternoon most likely as a result of the increase in relative humidity. The water vapor mixing ratio profiles generally showed smaller variations with altitude between day and night. We also compared simultaneous measurements of relative humidity, aerosol extinction, and aerosol optical thickness derived from the ARM SGP Raman lidar and in situ instruments on board a small aircraft flown routinely over the ARM SGP site. In contrast, the differences between the CARL and IAP aerosol extinction measurements are considerably larger. Aerosol extinction derived from the IAP measurements is, on average, about 30-40% less than values derived from the Raman lidar. The reasons for this difference are not clear, but may be related to the corrections for supermicron scattering and relative humidity that were applied to the IAP data. The investigators on this project helped to set up a major field mission (2003 Aerosol IOP) over the DOE ARM SGP site. One of the goals of the mission was to further evaluate the aerosol and water vapor retrievals from this lidar system

  11. Measurements of Aerosol Vertical Profiles and Optical Properties during INDOEX 1999 Using Micro-Pulse Lidars

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; Voss, Kenneth J.; Quinn, Patricia K.; Flatau, Piotr J.; Markowicz, Krzysztof; Campbell, James R.; Spinhirne, James D.; Gordon, Howard R.; Johnson, James E.; Starr, David OC. (Technical Monitor)

    2001-01-01

    lower troposphere) calculates extinction near the surface in agreement with the ship-level measurements only when the MBL aerosols are well mixed with aerosols above. Finally, a review of the MPL extinction profiles showed that the model of aerosol vertical extinction developed during an earlier INDOEX field campaign (at the Maldives) did not correctly describe the true vertical distribution over the greater Indian Ocean region. Using the average extinction profile and AOD obtained during marine conditions, a new model of aerosol vertical extinction was determined for marine atmospheres over the Indian Ocean. A new model of aerosol vertical extinction for polluted marine atmospheres was also developed using the average extinction profile and AOD obtained during marine conditions influenced by continental aerosols.

  12. Long-term impacts of aerosols on vertical development of cloud and precipitation

    SciTech Connect

    Li Z.; Liu Y.; Niu, F.; Fan, J.; Rosenfeld, D.; Ding, Y.

    2011-11-13

    Aerosols alter cloud density and the radiative balance of the atmosphere. This leads to changes in cloud microphysics and atmospheric stability, which can either suppress or foster the development of clouds and precipitation. The net effect is largely unknown, but depends on meteorological conditions and aerosol properties. Here, we examine the long-term impact of aerosols on the vertical development of clouds and rainfall frequencies, using a 10-year dataset of aerosol, cloud and meteorological variables collected in the Southern Great Plains in the United States. We show that cloud-top height and thickness increase with aerosol concentration measured near the ground in mixed-phase clouds-which contain both liquid water and ice-that have a warm, low base. We attribute the effect, which is most significant in summer, to an aerosol-induced invigoration of upward winds. In contrast, we find no change in cloud-top height and precipitation with aerosol concentration in clouds with no ice or cool bases. We further show that precipitation frequency and rain rate are altered by aerosols. Rain increases with aerosol concentration in deep clouds that have a high liquid-water content, but declines in clouds that have a low liquid-water content. Simulations using a cloud-resolving model confirm these observations. Our findings provide unprecedented insights of the long-term net impacts of aerosols on clouds and precipitation.

  13. MPL-Net Measurements of Aerosol and Cloud Vertical Distributions at Co-Located AERONET Sites

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; Campbell, James R.; Berkoff, Timothy A.; Spinhirne, James D.; Tsay, Si-Chee; Holben, Brent; Starr, David OC. (Technical Monitor)

    2002-01-01

    In the early 1990s, the first small, eye-safe, and autonomous lidar system was developed, the Micropulse Lidar (MPL). The MPL acquires signal profiles of backscattered laser light from aerosols and clouds. The signals are analyzed to yield multiple layer heights, optical depths of each layer, average extinction-to-backscatter ratios for each layer, and profiles of extinction in each layer. In 2000, several MPL sites were organized into a coordinated network, called MPL-Net, by the Cloud and Aerosol Lidar Group at NASA Goddard Space Flight Center (GSFC) using funding provided by the NASA Earth Observing System. tn addition to the funding provided by NASA EOS, the NASA CERES Ground Validation Group supplied four MPL systems to the project, and the NASA TOMS group contributed their MPL for work at GSFC. The Atmospheric Radiation Measurement Program (ARM) also agreed to make their data available to the MPL-Net project for processing. In addition to the initial NASA and ARM operated sites, several other independent research groups have also expressed interest in joining the network using their own instruments. Finally, a limited amount of EOS funding was set aside to participate in various field experiments each year. The NASA Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) project also provides funds to deploy their MPL during ocean research cruises. All together, the MPL-Net project has participated in four major field experiments since 2000. Most MPL-Net sites and field experiment locations are also co-located with sunphotometers in the NASA Aerosol Robotic Network. (AERONET). Therefore, at these locations data is collected on both aerosol and cloud vertical structure as well as column optical depth and sky radiance. Real-time data products are now available from most MPL-Net sites. Our real-time products are generated at times of AERONET aerosol optical depth (AOD) measurements. The AERONET AOD is used as input to our

  14. The effect of aerosol vertical profiles on satellite-estimated surface particle sulfate concentrations

    SciTech Connect

    Liu, Yang; Wang, Zifeng; Wang, Jun; Ferrare, Richard A.; Newsom, Rob K.; Welton, Ellsworth J.

    2011-02-15

    The aerosol vertical distribution is an important factor in determining the relationship between satellite retrieved aerosol optical depth (AOD) and ground-level fine particle pollution concentrations. We evaluate how aerosol profiles measured by ground-based lidar and simulated by models can help improve the association between AOD retrieved by the Multi-angle Imaging Spectroradiometer (MISR) and fine particle sulfate (SO4) concentrations using matched data at two lidar sites. At the Goddard Space Flight Center (GSFC) site, both lidar and model aerosol profiles marginally improve the association between SO4 concentrations and MISR fractional AODs, as the correlation coefficient between cross-validation (CV) and observed SO4 concentrations changes from 0.87 for the no-scaling model to 0.88 for models scaled with aerosol vertical profiles. At the GSFC site, a large amount of urban aerosols resides in the well-mixed boundary layer so the column fractional AODs are already excellent indicators of ground-level particle pollution. In contrast, at the Atmospheric Radiation Measurement Program (ARM) site with relatively low aerosol loadings, scaling substantially improves model performance. The correlation coefficient between CV and observed SO4 concentrations is increased from 0.58 for the no-scaling model to 0.76 in the GEOS-Chem scaling model, and the model bias is reduced from 17% to 9%. In summary, despite the inaccuracy due to the coarse horizontal resolution and the challenges of simulating turbulent mixing in the boundary layer, GEOS-Chem simulated aerosol profiles can still improve methods for estimating surface aerosol (SO4) mass from satellite-based AODs, particularly in rural areas where aerosols in the free troposphere and any long-range transport of aerosols can significantly contribute to the column AOD.

  15. Vertical distribution of aerosol extinction cross section and inference of aerosol imaginary index in the troposphere by lidar technique

    NASA Technical Reports Server (NTRS)

    Spinhirne, J. D.; Reagan, J. A.; Herman, B. M.

    1980-01-01

    The paper reports on vertical profiles of aerosol extinction and backscatter in the troposphere which were obtained from multi zenith angle lidar measurements. It is reported that a direct slant path solution was found to be not possible due to horizontal inhomogeneity of the atmosphere. Attention is given to the use of a regression analysis with respect to zenith angle for a layer integration of the angle dependent lidar equation in order to determine the optical thickness and aerosol extinction-to-backscatter ratio for defined atmospheric layers and the subsequent evaluation of cross-section profiles.

  16. Temporal variability of aerosol optical thickness vertical distribution observed from CALIOP

    NASA Astrophysics Data System (ADS)

    Toth, Travis D.; Zhang, Jianglong; Campbell, James R.; Reid, Jeffrey S.; Vaughan, Mark A.

    2016-08-01

    Temporal variability in the vertical distribution of aerosol optical thickness (AOT) derived from the 0.532 µm aerosol extinction coefficient is described using Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) observations over 8.5 years (June 2006 to December 2014). Temporal variability of CALIOP column-integrated AOT is largely consistent with total column AOT trends from several passive satellite sensors, such as the Moderate Resolution Imaging Spectroradiometer, Multiangle Imaging Spectroradiometer, and the Sea-viewing Wide Field-of-view Sensor. Globally, a 0.0002 AOT per year positive trend in deseasonalized CALIOP total column AOT for daytime conditions is attributed to corresponding changes in near-surface (i.e., 0.0-0.5 km or 0.5-1.0 km above ground level (agl)) aerosol particle loading, while a -0.0006 AOT per year trend during nighttime is attributed to elevated (i.e., 1.0-2.0 km or >2.0 km agl) aerosols. Regionally, increasing daytime CALIOP AOTs are found over Southern Africa and India, mostly due to changes in aerosol loading at the 1.0-2.0 km and 0.0-0.5 km agl layers, respectively. Decreasing daytime CALIOP AOTs are observed over Northern Africa, Eastern U.S., and South America (due mostly to elevated aerosol loading), while the negative CALIOP AOT trends found over Eastern China, Europe, and Western U.S. are due mostly to aerosol layers nearer the surface. To our knowledge, this study is the first to provide both a globally comprehensive estimation of the temporal variation in aerosol vertical distribution and an insight into passive sensor column AOT trends in the vertical domain.

  17. Vertical resolved separation of aerosol types using CALIPSO level-2 product

    NASA Astrophysics Data System (ADS)

    Giannakaki, Elina; Balis, Dimitris; Amiridis, Vassilis

    2011-11-01

    A lidar-based method was used to separate profiles of optical parameters due to different aerosol types over different European Aerosol Research LIdar NETwork (EARLINET) stations. The method makes uses of particle backscatter profiles at 532 nm and vertically resolved linear particle depolarization ratio measurements at the same wavelength. Values of particle depolarization ratio of 'pure' aerosol types (Saharan dust, biomass burning aerosols, anthropogenic aerosols, Volcanic ash aerosols) were taken from literature. Cases of CALIPSO space-borne lidar system were selected on the basis of different mixing state of the atmosphere over EARLINET stations. To identify the origin of air-masses four-day air mass back trajectories were computed using HYbrid Single-Particle Langrangian Integrated Trajectory (HYSPLIT) model, for different arrival heights, for the location and time under study was used. Also, the Dust REgional Atmospheric Modeling (DREAM) model was used to identify cases where dust from Saharan region was affecting the place under study. For our analysis we have used Atmospheric Volume Description (AVD), Cloud-Aerosol Discrimination (CAD) and extinction Quality Control (QC) flags to screen out CALIOP data. The method was applied for different horizontal resolution of 5, 25, 45 and 105 km. The height-resolved lidar results were finally compared with column-integrated products obtained with Aerosol Robotic Network Sun photometer (AERONET) in order to see to what extent Sun photometer columnar data are representative when different aerosol layers are present in the atmosphere.

  18. Vertical distribution of aerosols in the vicinity of Mexico City during MILAGRO-2006 Campaign

    SciTech Connect

    Lewandowski, P.A.; Kleinman, L.; Eichinger, W. E.; Holder, H.; Prueger, J.; Wang, J.

    2010-02-01

    On 7 March 2006, a mobile, ground-based, vertical pointing, elastic lidar system made a North-South transect through the Mexico City basin. Column averaged, aerosol size distribution (ASD) measurements were made on the ground concurrently with the lidar measurements. The ASD ground measurements allowed calculation of the column averaged mass extinction efficiency (MEE) for the lidar system (1064 nm). The value of column averaged MEE was combined with spatially resolved lidar extinction coefficients to produce total aerosol mass concentration estimates with the resolution of the lidar (1.5 m vertical spatial and 1 s temporal). Airborne ASD measurements from DOE G-1 aircraft made later in the day on 7 March 2006, allowed the evaluation of the assumptions of constant ASD with height and time used for estimating the column averaged MEE. The results showed that the aerosol loading within the basin is about twice what is observed outside of the basin. The total aerosol base concentrations observed in the basin are of the order of 200 {mu}g/m{sup 3} and the base levels outside are of the order of 100 {mu}g/m{sup 3}. The local heavy traffic events can introduce aerosol levels near the ground as high as 900 {mu}g/m{sup 3}. The article presents the methodology for estimating aerosol mass concentration from mobile, ground-based lidar measurements in combination with aerosol size distribution measurements. An uncertainty analysis of the methodology is also presented.

  19. Vertical profiles of aerosol volume from high-spectral-resolution infrared transmission measurements. I. Methodology.

    PubMed

    Eldering, A; Irion, F W; Chang, A Y; Gunson, M R; Mills, F P; Steele, H M

    2001-06-20

    The wavelength-dependent aerosol extinction in the 800-1250-cm(-1) region has been derived from ATMOS (atmospheric trace molecule spectroscopy) high-spectral-resolution IR transmission measurements. Using models of aerosol and cloud extinction, we have performed weighted nonlinear least-squares fitting to determine the aerosol-volume columns and vertical profiles of stratospheric sulfate aerosol and cirrus cloud volume. Modeled extinction by use of cold-temperature aerosol optical constants for a 70-80% sulfuric-acid-water solution shows good agreement with the measurements, and the derived aerosol volumes for a 1992 occultation are consistent with data from other experiments after the eruption of Mt. Pinatubo. The retrieved sulfuric acid aerosol-volume profiles are insensitive to the aerosol-size distribution and somewhat sensitive to the set of optical constants used. Data from the nonspherical cirrus extinction model agree well with a 1994 mid-latitude measurement indicating the presence of cirrus clouds at the tropopause.

  20. [Seasonal variations in the vertical distribution of aerosols during dry haze periods in regions around Shanghai].

    PubMed

    Xu, Ting-Ting; Qing, Yan; Geng, Fu-Hai; Chen, Yong-Hang; Zhang, Hua; Liu, Qiong; Ma, Xiao-Jun

    2012-07-01

    Based on the onboard lidar data from CALIPSO satellite of National Aeronautics and Space Administration (NASA) from January 2007 to November 2010, the vertical distribution of optical and micro-physical properties of aerosols around Shanghai during the haze periods when relative humidity less than 80% were revealed by analyzing the parameters of 532 nm total attenuated backscatter coefficient, volume depolarization ratio and total attenuated color ratio. The results showed that during dry haze periods, the scattering ability of lower troposphere (0-2 km) was the highest and the main constituents were regular aerosols. The scattering ability of the upper troposphere (8-10 km) was the lowest and the proportion of irregular aerosols was the highest among the five altitude layers. In addition, the scattering ability of the altitude range (2-8 km) was lower than that of the lower troposphere, and the scattering ability and irregularity of aerosols at different altitude levels within the range were close to each other. Fine particle aerosols were the dominant aerosols in altitude range of 0-10 km. To be noted, the proportion of fine particles decreased with increasing altitude within the altitude range of 2-8 km. The proportion of large and irregular aerosols were higher in spring, whereas the proportion of fine and regular aerosols were higher in summer. According to the analysis of a dry haze episode on May 7th, 2007, it was found that a mass of aerosols mainly distributed within the altitude range of 0-1.5 km and partially within the altitude range of 4.0-5.5 km. The HYSPLIT model was applied to analyze the sources of aerosols in the episode, and the results indicated that the dry haze was mainly caused not only by local emissions but also by the dust aerosols transported from Mongolia, the northwest and north of China by the airflow.

  1. Aerosol vertical distribution, optical properties and transport over Corsica (western Mediterranean)

    NASA Astrophysics Data System (ADS)

    Léon, J.-F.; Augustin, P.; Mallet, M.; Bourrianne, T.; Pont, V.; Dulac, F.; Fourmentin, M.; Lambert, D.; Sauvage, B.

    2015-03-01

    This paper presents the aerosol vertical distribution observed in the western Mediterranean between February and April 2011 and between February 2012 and August 2013. An elastic backscattering lidar was continuously operated at a coastal site in the northern part of Corsica Island (Cap Corse) for a total of more than 14 000 h of observations. The aerosol extinction coefficient retrieved from cloud-free lidar profiles are analyzed along with the SEVIRI satellite aerosol optical depth (AOD). The SEVIRI AOD was used to constrain the retrieval of the aerosol extinction profiles from the lidar range-corrected signal and to detect the presence of dust or pollution aerosols. The daily average AOD at 550 nm is 0.16 (±0.09) and ranges between 0.05 and 0.80. A seasonal cycle is observed with minima in winter and maxima in spring-summer. High AOD days (above 0.3 at 550 nm) represent less than 10% of the totality of daily observations and correspond to the large scale advection of desert dust from Northern Africa or pollution aerosols from Europe. The respective origin of the air masses is confirmed using FLEXPART simulations in the backward mode. Dust events are characterized by a large turbid layer between 2 and 5 km height while pollution events show a lower vertical development with a thick layer below 3 km in altitude. However low level dust transport is also reported during spring while aerosol pollution layer between 2 and 4 km height has been also observed. We report an effective lidar ratio at 355 nm for pollution aerosols 68 (±13) Sr while it is 63 (±18) Sr for dust. The daily mean AOD at 355 nm for dust events is 0.61 (±0.14) and 0.71 (±0.16) for pollution aerosols events.

  2. Vertical Profiles of Aerosol Optical Properties Over Central Illinois and Comparison with Surface and Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Sheridan P. J.; Andrews, E.; Ogren, J A.; Tackett, J. L.; Winker, D. M.

    2012-01-01

    Between June 2006 and September 2009, an instrumented light aircraft measured over 400 vertical profiles of aerosol and trace gas properties over eastern and central Illinois. The primary objectives of this program were to (1) measure the in situ aerosol properties and determine their vertical and temporal variability and (2) relate these aircraft measurements to concurrent surface and satellite measurements. Underflights of the CALIPSO satellite show reasonable agreement in a majority of retrieved profiles between aircraft-measured extinction at 532 nm (adjusted to ambient relative humidity) and CALIPSO-retrieved extinction, and suggest that routine aircraft profiling programs can be used to better understand and validate satellite retrieval algorithms. CALIPSO tended to overestimate the aerosol extinction at this location in some boundary layer flight segments when scattered or broken clouds were present, which could be related to problems with CALIPSO cloud screening methods. The in situ aircraft-collected aerosol data suggest extinction thresholds for the likelihood of aerosol layers being detected by the CALIOP lidar. These statistical data offer guidance as to the likelihood of CALIPSO's ability to retrieve aerosol extinction at various locations around the globe.

  3. On the Vertical Distribution of Aerosols and Long-Range Transport Inferred from Calipso Satellite Observations

    NASA Astrophysics Data System (ADS)

    Trepte, Charles; Winker, David; Kittaka, Chieko

    Knowledge on the long-range transport and evolution of aerosols originating from natural and anthropogenic sources is important for understanding their impact on the composition of the atmosphere and the climate system. Over the past several decades a wealth of information on aerosol distributions has been obtained from ground-based instrument networks, dedicated field experiments, and passive remote sensing satellite instruments that has helped to establish the primary aerosol transport pathways over the globe. In many instances, these pathways are broadly reproduced geographically in different chemical-transport models. The models, however, have difficulties at times with accurately projecting the vertical distribution of aerosols, which can lead to significant discrepancies in the lifetimes of the modeled aerosols. This issue is compounded at high latitudes where observations are especially sparse. New measurements from the CALIPSO satellite mission can provide additional insight on the vertical distribution of aerosols over the globe. The mission is a joint effort between the United States (NASA) and France (CNES) and was launched on April 28, 2008 into the A-train satellite constellation. CALIPSO's primary instrument is a two-wavelength polarization-sensitive lidar operating at 532 and 1064 nm with a repetition rate of 20.16 Hz. Lidar observations in the lower troposphere (¡ 8 km) have a vertical resolution of 30 m for the 532 nm channel and 60 m for the 1064 channel. The instrument has been operational since early June 2006. The CALIPSO data set reveals a rich distribution of aerosols in clear and cloudy scenes for both day and night conditions. Information on aerosol type is also available based on their wavelength dependence and polarization characteristics. From these data, a climatology on the vertical and geographic distribution and optical characteristics of aerosols (and clouds) is being developed that can aid diagnostic studies of aerosol transport

  4. Vertical distribution of aerosol number concentration in the troposphere over Siberia derived from airborne in-situ measurements

    NASA Astrophysics Data System (ADS)

    Arshinov, Mikhail Yu.; Belan, Boris D.; Paris, Jean-Daniel; Machida, Toshinobu; Kozlov, Alexandr; Malyskin, Sergei; Simonenkov, Denis; Davydov, Denis; Fofonov, Alexandr

    2016-04-01

    Knowledge of the vertical distribution of aerosols particles is very important when estimating aerosol radiative effects. To date there are a lot of research programs aimed to study aerosol vertical distribution, but only a few ones exist in such insufficiently explored region as Siberia. Monthly research flights and several extensive airborne campaigns carried out in recent years in Siberian troposphere allowed the vertical distribution of aerosol number concentration to be summarized. In-situ aerosol measurements were performed in a wide range of particle sizes by means of improved version of the Novosibirsk-type diffusional particle sizer and GRIMM aerosol spectrometer Model 1.109. The data on aerosol vertical distribution enabled input parameters for the empirical equation of Jaenicke (1993) to be derived for Siberian troposphere up to 7 km. Vertical distributions of aerosol number concentration in different size ranges averaged for the main seasons of the year will be presented. This work was supported by Interdisciplinary integration projects of the Siberian Branch of the Russian Academy of Science No. 35, No. 70 and No. 131; the Branch of Geology, Geophysics and Mining Sciences of RAS (Program No. 5); and Russian Foundation for Basic Research (grant No. 14-05-00526). Jaenicke R. Tropospheric aerosols, in Aerosol-Cloud-Climate Interactions, edited by P.V. Hobs. -Academic Press, San Diego, CA, 1993.- P. 1-31.

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

    PubMed

    Clarke, Antony; Kapustin, Vladimir

    2010-09-17

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

  6. Vertical Aerosol Backscatter Variability from an Airborne Focused Continuous Wave CO2 Lidar

    NASA Technical Reports Server (NTRS)

    Jarzembski, Maurice A.; Srivastava, Vandana; Rothermel, Jeffry

    1998-01-01

    Atmospheric aerosol backscatter measurements using a continuous wave focused Doppler lidar at 9.1 micron wavelength were obtained over western North America and the Pacific Ocean during 13 - 26 September, 1995 as part of National Aeronautics and Space Administration's (NASA) Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS) mission on board the NASA DC8 aircraft. Backscatter variability was measured for approximately 52 flight hours, covering equivalent horizontal distance of approximately 25,000 km in the troposphere. Quasi-vertical backscatter profiles were also obtained during various ascents and descents which ranged between approximately 0.1 to 12.0 km altitude. Aerosol haze layers were encountered at different altitudes. Similarities and differences for aerosol loading over land and over ocean were observed. A mid-tropospheric aerosol backscatter background mode was found with modal value approximately 1O(exp -10)/m/sr, consistent with previous airborne and ground-based datasets.

  7. Comparison of Aerosol Classification Results from Airborne High Spectral Resolution Lidar (HSRL) Measurements and the Calipso Vertical Feature Mask

    NASA Technical Reports Server (NTRS)

    Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Rogers, R. R.; Obland, M. D.; Butler, C. F.; Cook, A. L.; Harper, D. B.; Froyd, K. D.; Omar, A.

    2012-01-01

    Knowledge of the vertical profile, composition, concentration, and size of aerosols is required for assessing the direct impact of aerosols on radiation, the indirect effects of aerosols on clouds and precipitation, and attributing these effects to natural and anthropogenic aerosols. Because anthropogenic aerosols are predominantly submicrometer, fine mode fraction (FMF) retrievals from satellite have been used as a tool for deriving anthropogenic aerosols. Although column and profile satellite retrievals of FMF have been performed over the ocean, such retrievals have not yet been been done over land. Consequently, uncertainty in satellite estimates of the anthropogenic component of the aerosol direct radiative forcing is greatest over land, due in large part to uncertainties in the FMF. Satellite measurements have been used to detect and evaluate aerosol impacts on clouds; however, such efforts have been hampered by the difficulty in retrieving vertically-resolved cloud condensation nuclei (CCN) concentration, which is the most direct parameter linking aerosol and clouds. Recent studies have shown correlations between average satellite derived column aerosol optical thickness (AOT) and in situ measured CCN. However, these same studies, as well as others that use detailed airborne in situ measurements have noted that vertical variability of the aerosol distribution, impacts of relative humidity, and the presence of coarse mode aerosols such as dust introduce large uncertainties in such relations.

  8. Sensitivity of aerosol-induced effects on numerically simulated squall lines to the vertical distribution of aerosols

    NASA Astrophysics Data System (ADS)

    Lebo, Z. J.

    2013-12-01

    The sensitivity of aerosol-induced enhancement of convective strength and precipitation to the vertical distribution is analyzed in the context of numerically simulated squall lines. Recent investigations have hypothesized and demonstrated that an increase in an aerosol loading may lead to enhanced vertical updrafts and potentially more precipitation in a variety of deep convective systems. One of the generally accepted hypotheses for such an enhancement in convective strength suggests that the predominant effect of an increase in aerosol loading is related to enhanced latent heat release in the mid to upper levels of the convective cores. This enhancement has been attributed to an increase in supercooled liquid water that tends to exist in clouds formed in more polluted environments and it is suggested that this water is lofted from below the freezing level to the mixed-phase region of the cloud where the latent heating effects are maximized. However, deep convective cores are quite strong and so a reduction in cloud droplet size due to enhanced aerosol number concentration (which reduces the terminal fall speed) ought to have a negligible effect on the trajectory of the droplets (since the updraft velocity is much larger than the terminal fall speed). Thus, it should be expected that low-level aerosol pollution would have little to no effect on latent heating rates aloft since the droplets will end up in the mixed-phase region regardless of size. Moreover, more recent investigations have shown that aerosol perturbations, especially in squall lines, can lead to less intense cold pools and thus a more optimal state according to RKW theory. Numerical simulations of idealized squall lines are performed to specifically analyze the sensitivity of the aforementioned effects to the vertical distribution of aerosols. The simulations suggest that low-level air tends to either be detrained at the bottom of the convective cores or remains in the convective cores throughout

  9. Influence of atmospheric parameters on vertical profiles and horizontal transport of aerosols generated in the surf zone

    NASA Astrophysics Data System (ADS)

    Kusmierczyk-Michulec, J.; Tedeschi, G.; Van Eijk, A. M. J.; Piazzola, J.

    2013-10-01

    The vertical and horizontal transport of aerosols generated over the surf zone is discussed. Experimental data were collected during the second campaign of the Surf Zone Aerosol Experiment that took place in Duck NC (USA) in November 2007. The Empirical Orthogonal Function (EOF) method was used to analyze the vertical concentration gradients, and allowed separating the surf aerosols from aerosols advected from elsewhere. The numerical Marine Aerosol Concentration Model (MACMod) supported the analysis by confirming that the concentration gradients are more pronounced under stable conditions and that aerosol plumes are then more confined to the surface. The model also confirmed the experimental observations made during two boat runs along the offshore wind vector that surf-generated aerosols are efficiently advected out to sea over several tens of kilometers.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  11. Development of ATLID-MSI synergy for retrieving the vertical profiles of aerosol components

    NASA Astrophysics Data System (ADS)

    Kudo, R.; Nishizawa, T.; Higurashi, A.; Sugimoto, N.; Oikawa, E.

    2014-12-01

    EarthCARE is an earth observation satellite and will be launched in 2016. Using its two sensors, ATLID (High spectral resolution lidar) and MSI (Multi-spectral imager), we are developing the synergy algorithm to retrieve the vertical profiles of extinction coefficients at 355 nm of four aerosol components (Water-soluble, black carbon, dust, and sea-salt particles), and the column mean of mode radii of water-soluble and dust particles. The ATLID data are extinction coefficient, backscatter coefficient, and depolarization ratio for total aerosols at 355 nm. The MSI data are radiances at 670 and 865 nm. The dry volume concentrations of four aerosol components at each altitude and the mode radii of water-soluble and dust particles in the column are simultaneously optimized to ATLID and MSI data by the gauss newton method. After the optimization, the vertical profiles of the extinction coefficient at 355 nm of four aerosol components are obtained. The size distributions of four aerosol components are assumed to be a lognormal distribution. The refractive indices of four aerosol components are given from previously observational studies. The humidity growth is considered for water-soluble and sea-salt particles. The volume concentration and the mode radius of the sea-salt particle are parameterized using the surface wind speed on the ocean. We assumed that the shape of the water-soluble, black carbon, and sea-salt particles are spherical, and the shape of the dust particle is spheroidal. We tested the algorithm using the ATLID and MSI data simulated using clean, dust-transported, and smoke-transported aerosols. The extinction coefficients of each component at 355 nm are retrieved well. The mode radius of water-soluble and dust particles were somehow overestimated.

  12. Aerosol vertical distribution over east China from RIEMS-Chem simulation in comparison with CALIPSO measurements

    NASA Astrophysics Data System (ADS)

    Li, Jiawei; Han, Zhiwei

    2016-10-01

    The horizontal and vertical distributions of aerosol extinction coefficient (AEC) and mass concentration over east China in October 2010 were investigated by using an online-coupled regional climate model and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) data. Model performance was evaluated comprehensively against ground observations of meteorological variables and PM10 concentrations and CALIPSO retrieved AEC profiles, which demonstrated a good ability of the model in simulating spatial distribution and evolution of aerosol concentration and optical properties. Severe pollution episodes were found over wide areas of east China during the study period, with the maximum mean PM10 concentration exceeding 200 μg m-3 in the Chongqing district and a part of the lower reaches of the Yellow River on 8-10 October. Both CALIPSO retrievals and model simulations revealed high AEC values (≥1 km-1) often occurred within 2 km above ground over most areas of east China. AEC vertical profile in or in the vicinity of China major cities along CALIPSO orbit track exhibited two typical features: one was AEC reached its maximum (∼4 km-1) near the surface (<200 m) and decreased rapidly to < 0.1 km-1 at altitudes above 1 km, another one was AEC peaked at higher altitudes of about 0.5-1 km with a maximum up to 3 km-1. AEC vertical profile was strongly dependent on vertical distribution of both aerosol concentration, composition and relative humidity. The vertical cross sections over typical regions of east China exhibited a decreasing AEC in magnitude from the continent to the China seas. Over the continent, AEC was either maximum near the surface or peaked at higher altitudes (0.5-1.0 km) due to increases of relative humidity or aerosol concentration in those regions, whereas over the seas of China, AEC profile was characterized by peak values at an altitude around 1 km, mainly due to an elevated relative humidity there, which favored rapid aerosol

  13. Vertical Profiles of Cloud Condensation Nuclei, Condensation Nuclei, Optical Aerosol, Aerosol Optical Properties, and Aerosol Volatility Measured from Balloons

    NASA Technical Reports Server (NTRS)

    Deshler, T.; Snider, J. R.; Vali, G.

    1998-01-01

    Under the support of this grant a balloon-borne gondola containing a variety of aerosol instruments was developed and flown from Laramie, Wyoming, (41 deg N, 105 deg W) and from Lauder, New Zealand (45 deg S, 170 deg E). The gondola includes instruments to measure the concentrations of condensation nuclei (CN), cloud condensation nuclei (CCN), optically detectable aerosol (OA.) (r greater than or equal to 0.15 - 2.0 microns), and optical scattering properties using a nephelometer (lambda = 530 microns). All instruments sampled from a common inlet which was heated to 40 C on ascent and to 160 C on descent. Flights with the CN counter, OA counter, and nephelometer began in July 1994. The CCN counter was added in November 1994, and the engineering problems were solved by June 1995. Since then the flights have included all four instruments, and were completed in January 1998. Altogether there were 20 flights from Laramie, approximately 5 per year, and 2 from Lauder. Of these there were one or more engineering problems on 6 of the flights from Laramie, hence the data are somewhat limited on those 6 flights, while a complete data set was obtained from the other 14 flights. Good CCN data are available from 12 of the Laramie flights. The two flights from Lauder in January 1998 were successful for all measurements. The results from these flights, and the development of the balloon-bome CCN counter have formed the basis for five conference presentations. The heated and unheated CN and OA measurements have been used to estimate the mass fraction of the aerosol volatile, while comparisons of the nephelometer measurements were used to estimate the light scattering, associated with the volatile aerosol. These estimates were calculated for 0.5 km averages of the ascent and descent data between 2.5 km and the tropopause, near 11.5 km.

  14. Aerosol interactions between the surface and the atmosphere: Urban fluxes, forest canopy vertical exchange, and wintertime urban patterns

    NASA Astrophysics Data System (ADS)

    Grivicke, Rasa

    Atmospheric aerosols play a major role in regional atmospheric chemistry and air quality, while on a global scale, aerosol processes continue to represent the largest source of uncertainty related to climate change. An important aspect of understanding the role of aerosols in these areas is to document the vertical exchange of aerosols with the surface in both urban and rural landscapes since the vertical exchange represents important sources and sinks of aerosols on regional and global scales. In this dissertation, investigation of aerosol dynamics is described for three separate field studies. First, urban eddy covariance flux measurements were made from a building rooftop in Mexico City using a quadrupole aerosol mass spectrometer (Q-AMS) to determine the fluxes of aerosol species to/from the urban landscape. Second, conditional sampling of fine particles in updrafts and downdrafts was performed above a pine forest in Colorado using a thermal desorption chemical ionization mass spectrometer (TD-CIMS) to investigate the relative strengths of sources and sinks for speciated aerosol in a forest environment. Third, the aerosol and gas phase pollutant patterns, measured in Boise, ID during wintertime inversion conditions, were analyzed with respect to the daily evolution of the planetary boundary layer depth and surface meteorological conditions. This dissertation describes the methods used for each of the three studies and summarizes the analysis of the results.

  15. Seismic Behaviour of Vertical Mass Isolated Structures

    SciTech Connect

    Nekooei, M.; Ziyaeifar, M.

    2008-07-08

    In this paper, the seismic behaviour of vertical mass isolated structures against the earthquake is studied. These structures are assumed to be consisted of two subsystems. Mass subsystem possesses low lateral stiffness but carries the major part of mass of the system. Stiffness subsystem, however, controls the deformation of the mass subsystem and attributes with much higher stiffness. The isolator layer is, therefore, located in between the mass and the stiffness subsystems and assumed to be a viscous damper layer. The analytical model used for this investigation is a dual mass-spring model which is an extended form of the three element Maxwell model. In this study, the ability of mass isolation techniques in reducing earthquake effects on buildings with two approaches, parametric and numerical approaches, is shown. In the parametric approach, by definition an isolation factor for structure and determination the dynamic characteristics of system, the relative optimum value of the isolator damping coefficient is obtained. The results provide an insight on role of relative stiffness and mass ratio of the two subsystems. Finally, in the numerical approach, the spectral responses of these structures due to the earthquake are investigated. The results show a noticeable decrease in earthquake input force to vertical mass isolated structures in comparison with non-isolated structures.

  16. What controls the vertical distribution of aerosol? Relationships between process sensitivity in HadGEM3-UKCA and inter-model variation from AeroCom Phase II

    NASA Astrophysics Data System (ADS)

    Kipling, Z.; Stier, P.; Johnson, C. E.; Mann, G. W.; Bellouin, N.; Bauer, S. E.; Bergman, T.; Chin, M.; Diehl, T.; Ghan, S. J.; Iversen, T.; Kirkevåg, A.; Kokkola, H.; Liu, X.; Luo, G.; van Noije, T.; Pringle, K. J.; von Salzen, K.; Schulz, M.; Seland, Ø.; Skeie, R. B.; Takemura, T.; Tsigaridis, K.; Zhang, K.

    2015-09-01

    The vertical profile of aerosol is important for its radiative effects, but weakly constrained by observations on the global scale, and highly variable among different models. To investigate the controlling factors, we investigate the effects of individual processes in one particular model (HadGEM3-UKCA), and compare the resulting diversity of aerosol vertical profiles with the inter-model diversity from the AeroCom Phase II control experiment. In this way we show that (in this model at least) the vertical profile is controlled by a relatively small number of processes, although these vary among aerosol components and particle sizes. We also show that sufficiently coarse variations in these processes can produce a similar diversity to that among different models in terms of the global mean profile and zonal-mean vertical position. However, there are features of certain models' profiles that cannot be reproduced, suggesting the influence of further structural differences between models. Convective transport is found to be very important in controlling the vertical profile of all aerosol components by mass. In-cloud scavenging is very important for all except mineral dust. Growth by condensation is important for sulphate and carbonaceous aerosol (along with aqueous oxidation for the former and ageing by soluble material for the latter). The vertical extent of biomass-burning emissions into the free troposphere is also important for the profile of carbonaceous aerosol. Boundary-layer mixing plays a dominant role for sea-salt and mineral dust, which are emitted only from the surface. Dry deposition and below-cloud scavenging are important for the profile of mineral dust only. In this model, the microphysical processes of nucleation, condensation and coagulation dominate the vertical profile of the smallest particles by number, while the profiles of larger particles are controlled by the same processes as the component mass profiles, plus the size distribution of

  17. What Controls the Vertical Distribution of Aerosol? Relationships Between Process Sensitivity in HadGEM3-UKCA and Inter-Model Variation from AeroCom Phase II

    NASA Technical Reports Server (NTRS)

    Kipling, Zak; Stier, Philip; Johnson, Colin E.; Mann, Graham W.; Bellouin, Nicolas; Bauer, Susanne E.; Bergman, Tommi; Chin, Mian; Diehl, Thomas; Ghan, Steven J.; Tsigaridis, Kostas

    2016-01-01

    The vertical profile of aerosol is important for its radiative effects, but weakly constrained by observations on the global scale, and highly variable among different models. To investigate the controlling factors in one particular model, we investigate the effects of individual processes in HadGEM3-UKCA and compare the resulting diversity of aerosol vertical profiles with the inter-model diversity from the AeroCom Phase II control experiment. In this way we show that (in this model at least) the vertical profile is controlled by a relatively small number of processes, although these vary among aerosol components and particle sizes. We also show that sufficiently coarse variations in these processes can produce a similar diversity to that among different models in terms of the global-mean profile and, to a lesser extent, the zonal-mean vertical position. However, there are features of certain models' profiles that cannot be reproduced, suggesting the influence of further structural differences between models. In HadGEM3-UKCA, convective transport is found to be very important in controlling the vertical profile of all aerosol components by mass. In-cloud scavenging is very important for all except mineral dust. Growth by condensation is important for sulfate and carbonaceous aerosol (along with aqueous oxidation for the former and ageing by soluble material for the latter). The vertical extent of biomass-burning emissions into the free troposphere is also important for the profile of carbonaceous aerosol. Boundary-layer mixing plays a dominant role for sea salt and mineral dust, which are emitted only from the surface. Dry deposition and below-cloud scavenging are important for the profile of mineral dust only. In this model, the microphysical processes of nucleation, condensation and coagulation dominate the vertical profile of the smallest particles by number (e.g. total CN >3 nm), while the profiles of larger particles (e.g. CN>100 nm) are controlled by the

  18. What controls the vertical distribution of aerosol? Relationships between process sensitivity in HadGEM3-UKCA and inter-model variation from AeroCom Phase II

    NASA Astrophysics Data System (ADS)

    Kipling, Zak; Stier, Philip; Johnson, Colin E.; Mann, Graham W.; Bellouin, Nicolas; Bauer, Susanne E.; Bergman, Tommi; Chin, Mian; Diehl, Thomas; Ghan, Steven J.; Iversen, Trond; Kirkevåg, Alf; Kokkola, Harri; Liu, Xiaohong; Luo, Gan; van Noije, Twan; Pringle, Kirsty J.; von Salzen, Knut; Schulz, Michael; Seland, Øyvind; Skeie, Ragnhild B.; Takemura, Toshihiko; Tsigaridis, Kostas; Zhang, Kai

    2016-02-01

    The vertical profile of aerosol is important for its radiative effects, but weakly constrained by observations on the global scale, and highly variable among different models. To investigate the controlling factors in one particular model, we investigate the effects of individual processes in HadGEM3-UKCA and compare the resulting diversity of aerosol vertical profiles with the inter-model diversity from the AeroCom Phase II control experiment. In this way we show that (in this model at least) the vertical profile is controlled by a relatively small number of processes, although these vary among aerosol components and particle sizes. We also show that sufficiently coarse variations in these processes can produce a similar diversity to that among different models in terms of the global-mean profile and, to a lesser extent, the zonal-mean vertical position. However, there are features of certain models' profiles that cannot be reproduced, suggesting the influence of further structural differences between models. In HadGEM3-UKCA, convective transport is found to be very important in controlling the vertical profile of all aerosol components by mass. In-cloud scavenging is very important for all except mineral dust. Growth by condensation is important for sulfate and carbonaceous aerosol (along with aqueous oxidation for the former and ageing by soluble material for the latter). The vertical extent of biomass-burning emissions into the free troposphere is also important for the profile of carbonaceous aerosol. Boundary-layer mixing plays a dominant role for sea salt and mineral dust, which are emitted only from the surface. Dry deposition and below-cloud scavenging are important for the profile of mineral dust only. In this model, the microphysical processes of nucleation, condensation and coagulation dominate the vertical profile of the smallest particles by number (e.g. total CN > 3 nm), while the profiles of larger particles (e.g. CN > 100 nm) are controlled by the

  19. How well can we Measure the Vertical Profile of Tropospheric Aerosol Extinction?

    NASA Technical Reports Server (NTRS)

    Schmid, Beat; Ferrare, R.; Flynn, C.; Elleman, R.; Covert, D.; Strawa, A.; Welton, E.; Turner, D.; Jonsson, H.; Redemann, J.

    2005-01-01

    The recent Department of Energy Atmospheric Radiation Measurement (ARM) Aerosol Intensive Operations Period (MOP, May 2003) yielded one of the best measurement sets obtained to-date to assess our ability to measure the vertical profile of ambient aerosol extinction sigma(sub ep)(lambda) in the lower troposphere. During one month, a heavily instrumented aircraft with well characterized aerosol sampling ability carrying well proven and new aerosol instrumentation, devoted most of the 60 available flight hours to flying vertical profiles over the heavily instrumented ARM Southern Great Plains (SGP) Climate Research Facility (CRF). This allowed us to compare vertical extinction profiles obtained from 6 different instuments: airborne Sun photometer (AATS-14), airborne nephelometer/absorption photometer, airborne cavity ring-down system, ground-based Raman lidar and 2 ground-based elastic backscatter lidars. We find the in-situ measured sigma(sub ep)(lambda) to be lower than the AATS-14 derived values. Bias differences are 0.002 - 0.004 K/m equivalent to 12-17% in the visible, or 45% in the near-infrared. On the other hand, we find that with respect to AATS-14, the lidar sigma(sub ep)(lambda) are higher. An unnoticed loss of sensitivity of the Raman lidar had occurred leading up to AIOP and we expect better agreement from the recently restored system looking at the collective results from 6 field campaigns conducted since 1996, airborne in situ measurements of sigma(sub ep)(lambda) tend to be biased slightly low (17% at visible wavelengths) when compared to airborne Sun photometer sigma(sub ep)(lambda). On the other hand, sigma(sub ep)(lambda) values derived from lidars tend to have no or positive biases. From the bias differences we conclude that the typical systematic error associated with measuring the tropospheric vertical profile of the ambient aerosol extinction with current state of-the art instrumentation is 15-20% at visible wavelengths and potentially larger in

  20. Relativistic slim disks with vertical structure

    NASA Astrophysics Data System (ADS)

    Sądowski, A.; Abramowicz, M.; Bursa, M.; Kluźniak, W.; Lasota, J.-P.; Różańska, A.

    2011-03-01

    We report on a scheme for incorporating vertical radiative energy transport into a fully relativistic, Kerr-metric model of optically thick, advective, transonic alpha disks. Our code couples the radial and vertical equations of the accretion disk. The flux was computed in the diffusion approximation, and convection is included in the mixing-length approximation. We present the detailed structure of this "two-dimensional" slim-disk model for α = 0.01. We then calculated the emergent spectra integrated over the disk surface. The values of surface density, radial velocity, and the photospheric height for these models differ by 20%-30% from those obtained in the polytropic, height-averaged slim disk model considered previously. However, the emission profiles and the resulting spectra are quite similar for both types of models. The effective optical depth of the slim disk becomes lower than unity for high values of the alpha parameter and for high accretion rates.

  1. Vertical dependence of black carbon, sulphate and biomass burning aerosol radiative forcing

    NASA Astrophysics Data System (ADS)

    Samset, Bjørn H.; Myhre, Gunnar

    2011-12-01

    A global radiative transfer model is used to calculate the vertical profile of shortwave radiative forcing from a prescribed amount of aerosols. We study black carbon (BC), sulphate (SO4) and a black and organic carbon mixture typical of biomass burning (BIO), by prescribing aerosol burdens in layers between 1000 hPa and 20 hPa and calculating the resulting direct radiative forcing divided by the burden (NDRF). We find a strong sensitivity in the NDRF for BC with altitude, with a tenfold increase between BC close to the surface and the lower part of the stratosphere. Clouds are a major contributor to this dependence with altitude, but other factors also contribute. We break down and explain the different physical contributors to this strong sensitivity. The results show a modest regional dependence of the altitudinal dependence of BC NDRF between industrial regions, while for regions with properties deviating from the global mean NDRF variability is significant. Variations due to seasons and interannual changes in cloud conditions are found to be small. We explore the effect that large altitudinal variation in NDRF may have on model estimates of BC radiative forcing when vertical aerosol distributions are insufficiently constrained, and discuss possible applications of the present results for reducing inter-model differences.

  2. Three-dimensional structure of aerosol in China: A perspective from multi-satellite observations

    NASA Astrophysics Data System (ADS)

    Guo, Jianping; Liu, Huan; Wang, Fu; Huang, Jingfeng; Xia, Feng; Lou, Mengyun; Wu, Yerong; Jiang, Jonathan H.; Xie, Tao; Zhaxi, Yangzong; Yung, Yuk L.

    2016-09-01

    Using eight years (2006-2014) of passive (MODIS/Aqua and OMI/Aura) and active (CALIOP/CALIPSO) satellite measurements of aerosols, we yield a three-dimensional (3D) distribution of the frequency of occurrence (FoO) of aerosols over China. As an indicator of the vertical heterogeneity of aerosol layers detected by CALIOP, two types of Most Probable Height (MPH), including MPH_FoO and MPH_AOD, are deduced. The FoO of "Total Aerosol" reveals significant geographical dependence. Eastern China showed much stronger aerosol FoD than northwestern China. The FoO vertical structures of aerosol layer are strongly dependent on altitudes. Among the eight typical ROIs analyzed, aerosol layers over the Gobi Desert have the largest occurrence probability located at an altitude as high as 2.83 km, as compared to 1.26 km over Beijing-Tianjin-Hebei. The diurnal variation (nighttime-daytime) in MPH_AOD varies from an altitude as low as 0.07 km over the Sichuan basin to 0.27 km over the Gobi Desert, whereas the magnitude of the diurnal variation in terms of MPH_AOD is six times as large as the MPH_FoO, mostly attributable to the day/night lidar SNR difference. Also, the 3D distribution of dust and smoke aerosols was presented. The multi-sensor synergized 3D observations of dust aerosols, frequently observed in the zonal belt of 38°N-45°N, is markedly different from that of smoke aerosols that are predominantly located in the eastern and southern parts. The 3D FoO distribution of dust indicates a west-to-east passageway of dust originating from the westernmost Taklimakan Desert all the way to North China Plain (NCP). The findings from the multi-sensor synergetic observations greatly improved our understanding on the long-range aerosol dispersion, transport and passageway over China.

  3. The Vertical Distribution of Aerosols Over the Atmospheric Radiation Measurement Southern Great Plains Site Measured versus Modeled

    SciTech Connect

    Ferrare, R.; Turner, D.D.; Clayton, M.; Guibert, S.; Schulz, M.; Chin, M.

    2005-03-18

    Aerosol extinction profiles measured by the Department of Energy Atmospheric Radiation Measurement (ARM) Climate Research Facility Raman lidar are used to evaluate aerosol extinction profiles and aerosol optical thickness (AOT) simulated by aerosol models as part of the Aerosol module inter- Comparison in global models (AEROCOM) project. This project seeks to diagnose aerosol modules of global models and subsequently identify and eliminate weak components in aerosol modules used for global modeling; AEROCOM activities also include assembling data sets to be used in the evaluations. The AEROCOM average aerosol extinction profiles typically show good agreement with the Raman lidar profiles for altitudes above about 2 km; below 2 km the average model profiles are significantly (30-50%) lower than the Raman lidar profiles. The vertical variability in the average aerosol extinction profiles simulated by these models is less than the variability in the corresponding Raman lidar pro files. The measurements also show a much larger diurnal variability than the Interaction with Chemistry and Aerosols (INCA) model, particularly near the surface where there is a high correlation between aerosol extinction and relative humidity.

  4. Comparison of vertical aerosol extinction coefficients from in-situ and LIDAR measurements

    NASA Astrophysics Data System (ADS)

    Rosati, B.; Herrmann, E.; Bucci, S.; Fierli, F.; Cairo, F.; Gysel, M.; Tillmann, R.; Größ, J.; Gobbi, G. P.; Di Liberto, L.; Di Donfrancesco, G.; Wiedensohler, A.; Weingartner, E.; Virtanen, A.; Mentel, T. F.; Baltensperger, U.

    2015-07-01

    Vertical profiles of aerosol optical properties were explored in a case study near the San Pietro Capofiume (SPC) ground station during the PEGASOS Po Valley campaign in the summer of 2012. A Zeppelin NT airship was employed to investigate the effect of the dynamics of the planetary boundary layer at altitudes between ~ 50-800 m above ground. Determined properties included the aerosol size distribution, the hygroscopic growth factor, the effective index of refraction and the light absorption coefficient. The first three parameters were used to retrieve the light scattering coefficient. Simultaneously, direct measurements of both the scattering and absorption coefficient were carried out at the SPC ground station. Additionally, a LIDAR system provided aerosol extinction coefficients for a vertically resolved comparison between in-situ and remote sensing results. First, the airborne results at low altitudes were validated with the ground measurements. Agreement within approximately ±25 and ±20% was found for the dry scattering and absorption coefficient, respectively. The single scattering albedo, ranged between 0.83 to 0.95, indicating the importance of the absorbing particles in the Po Valley region. A clear layering of the atmosphere was observed during the beginning of the flight (until ~ 10 local time) before the mixed layer (ML) was fully developed. Highest extinction coefficients were found at low altitudes, in the new ML, while values in the residual layer, which could be probed at the beginning of the flight at elevated altitudes, were lower. At the end of the flight (after ~ 12 local time) the ML was fully developed, resulting in constant extinction coefficients at all altitudes measured on the Zeppelin NT. LIDAR results captured these dynamic features well and good agreement was found for the extinction coefficients compared to the in-situ results, using fixed LIDAR ratios (LR) between 30 and 70 sr for the altitudes probed with the Zeppelin. These LR are

  5. Variability in Vertical Profiles of Water Vapor Associated with African Aerosol over the Tropical Atlantic

    NASA Astrophysics Data System (ADS)

    Huang, J.; Zhang, C.; Prospero, J. M.

    2007-12-01

    We used four years (2003-2006) of MODIS aerosol optical depth and concurrent AIRS profiled water vapor to explore how the vertical distribution of water vapor may systematically change with outbreaks of African aerosol over the tropical Atlantic Ocean. The first step was to look for a relationship in the Barbados region using in-situ Barbados dust record and the profiled relative humidity from meteorological soundings. We extended the study to the synoptic scale in the West Indies using the MODIS and AIRS products. In the tropical Atlantic, preliminary results indicate that water vapor at 850-1000 hPa is significantly less in July on dusty days than clean days over the northeastern tropical Atlantic [5-25N, 30-20W] where African dust is predominant. In contrast, over the southeastern tropical Atlantic [15S-0, 5W-10E], where African biomass burning smoke prevails, water vapor at 600-1000 hPa is significantly higher in August on smoky days than clean days. Additionally, in January when African mixed aerosol (dust and smoke) is anomalously high over the equatorial eastern tropical Atlantic [5S-5N, 15W-5E], less water vapor is observed at two levels: 925-1000 hPa and 500-600 hPa. It is hypothesized that these results are associated with the non-hygroscopic nature of African dust, the hygroscopic properties of African smoke, and their transport pathways over the tropical Atlantic. These results are useful in the design and diagnostics of model simulations of climate effects of aerosols such as aerosol related precipitation change.

  6. Vertical motion of near-surface aerosols close to breaking waves

    NASA Astrophysics Data System (ADS)

    Lienert, Barry; Porter, John; Sharma, Shiv

    2005-10-01

    We have used two-dimensional correlation on two-dimensional extinction cross-sections measured by a scanning lidar to determine the velocity structure of the salt-spray aerosols. The lidar scans were collected over a reef at Bellows Beach, on the Northeast side of Oahu, Hawaii. The resulting velocity streamlines suggest that lifting of sea-spray aerosols as high as 200 m occurs in the vicinity of opposing horizontal roll vortices. The velocities vary rapidly over distances of less than 500 m and show a complex pattern which is inadequately represented by conventional anemometer measurements.

  7. Atmospheric Aerosol and Thermal Structure in the Boundary Layer Over the Los Angeles Basin

    NASA Technical Reports Server (NTRS)

    Johnson, Warren B.

    1973-01-01

    A field study using a mobile lidar was recently conducted in the L. A. Basin, California, to (1) examine the relationship between the vertical aerosol and the thermal structure, and (2) map the vertical aerosol structure in the atmospheric boundary layer over the basin. These data are needed for use in the development of a mixing-depth submodel required for photochemical air Quality simulation models. Toward these ends, a series of lidar aerosol measurements in conjunction with balloon and aircraft temperature soundings were taken at a site in El Monte, and in a mobile mode along a 90-mile freeway loop between El Monte, Santa Monica, and Long Beach. The lidar data are presented in the form of time-height and distance-height cross sections. The results indicate that, although aerosol concentrations are frequently present above the base of the marine inversion, these are generally in stratified layers in contrast to the more uniform nature of the lower convective layer, permitting the mixing depth to be distinguished on this basis. The lidar-derived mixing depths are well correlated (within 100 m) with daytime temperature inversions. Other significant features shown by the lidar data include large Basin-wide mixing-depth variations, waves with amplitudes of 200-300 m and wavelengths of 1000-1500 m on the lower aerosol layer, and apparent aerosol "chimneys" with overrunning in the vicinity of convergence zones.

  8. Vertical Profiles of Aerosol Particle Sizes using MGS/TES and MRO/MCS

    NASA Astrophysics Data System (ADS)

    Wolff, M. J.; Clancy, R. T.; Smith, M. D.; Benson, J. L.; McConnochie, T. H.; Pankine, A.

    2012-12-01

    Vertical variations in aerosol particle sizes often have a dramatic impact on the state and evolution of the Martian atmosphere. Recent analyses of data from the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM), the Thermal Emission Spectrometer (TES), and the Mars Climate Sounder (MCS) instruments offer some long overdue progress in constraining this aspect of aerosols. However, significantly more work remains to be done along these lines in order to better constrain and inform modern dynamical simulations of the Martian atmosphere. Thus, the primary goal of our work is to perform retrievals of particle size as a function of altitude for both dust and water ice aerosols. The choice of the TES and MCS dataset, with pole-to-pole coverage over a period of nearly eight martian years, provides the crucial systematic temporal and spatial sampling. Our presentation will include: 1) A summary of our limb radiative transfer algorithms and retrieval schemes; 2) The initial results of the application of our particle size retrieval scheme to the 2001 TES and 2007 MCS observations of those planet encircling dust events; 3) Near-term plans for for additional retrievals (aphelion cloud season, lower optical depth locations and seasons, etc.); 4) Location of the archive to be used for the distribution of the derived profiles and associated retrieval metadata.

  9. Vertical profiling of aerosol hygroscopic properties in the planetary boundary layer during the PEGASOS campaigns

    NASA Astrophysics Data System (ADS)

    Rosati, B.; Gysel, M.; Rubach, F.; Mentel, T. F.; Goger, B.; Poulain, L.; Schlag, P.; Miettinen, P.; Pajunoja, A.; Virtanen, A.; Bialek, J.; Klein Baltink, H.; Henzing, J. S.; Größ, J.; Gobbi, G. P.; Wiedensohler, A.; Kiendler-Scharr, A.; O'Dowd, C.; Decesari, S.; Facchini, M. C.; Weingartner, E.; Baltensperger, U.

    2015-03-01

    Airborne measurements of the aerosol hygroscopic and optical properties as well as chemical composition were performed in the Netherlands and northern Italy on board of a Zeppelin NT airship during the PEGASOS field campaigns in 2012. The vertical changes in aerosol properties during the development of the mixing layer were studied. Hygroscopic growth factors (GF) at 95% relative humidity were determined using the white-light humidified optical particles spectrometer (WHOPS) for dry diameters of 300 and 500 nm particles. These measurements were supplemented by an aerosol mass spectrometer (AMS) and an aethalometer providing information on the aerosol chemical composition. Several vertical profiles between 100 and 700 m a.g. were flown just after sunrise close to the San Pietro Capofiume ground station in the Po Valley, Italy. During the early morning hours the lowest layer (newly developing mixing layer) contained a high nitrate fraction (20%) which was coupled with enhanced hygroscopic growth. In the layer above (residual layer) small nitrate fractions of ~ 2% were measured as well as low GFs. After full mixing of the layers, typically around noon and with increased temperature, the nitrate fraction decreased to 2% at all altitudes and led to similar hygroscopicity values as found in the residual layer. These distinct vertical and temporal changes underline the importance of airborne campaigns to study aerosol properties during the development of the mixed layer. The aerosol was externally mixed with 22 and 67% of the 500 nm particles in the range GF < 1.1 and GF > 1.5, respectively. Contributors to the non-hygroscopic mode in the observed size range are most likely mineral dust and biological material. Mean hygroscopicity parameters (κ) were 0.34, 0.19 and 0.18 for particles in the newly forming mixing layer, residual layer and fully mixed layer, respectively. These results agree well with those from chemical analysis which found values of κ = 0.27, 0.21 and 0

  10. Estimation of surface-level PM concentration from satellite observation taking into account the aerosol vertical profiles and hygroscopicity.

    PubMed

    Kim, Kwanchul; Lee, Kwon H; Kim, Ji I; Noh, Youngmin; Shin, Dong H; Shin, Sung K; Lee, Dasom; Kim, Jhoon; Kim, Young J; Song, Chul H

    2016-01-01

    Surface-level PM10 distribution was estimated from the satellite aerosol optical depth (AOD) products, taking the account of vertical profiles and hygroscopicity of aerosols over Jeju, Korea during March 2008 and October 2009. In this study, MODIS AOD data from the Terra and Aqua satellites were corrected with aerosol extinction profiles and relative humidity data. PBLH (Planetary Boundary Layer Height) was determined from MPLNET lidar-derived aerosol extinction coefficient profiles. Through statistical analysis, better agreement in correlation (R = 0.82) between the hourly PM10 concentration and hourly average Sunphotometer AOD was the obtained when vertical fraction method (VFM) considering Haze Layer Height (HLH) and hygroscopic growth factor f(RH) was used. The validity of the derived relationship between satellite AOD and surface PM10 concentration clearly demonstrates that satellite AOD data can be utilized for remote sensing of spatial distribution of regional PM10 concentration. PMID:26421659

  11. Estimation of surface-level PM concentration from satellite observation taking into account the aerosol vertical profiles and hygroscopicity.

    PubMed

    Kim, Kwanchul; Lee, Kwon H; Kim, Ji I; Noh, Youngmin; Shin, Dong H; Shin, Sung K; Lee, Dasom; Kim, Jhoon; Kim, Young J; Song, Chul H

    2016-01-01

    Surface-level PM10 distribution was estimated from the satellite aerosol optical depth (AOD) products, taking the account of vertical profiles and hygroscopicity of aerosols over Jeju, Korea during March 2008 and October 2009. In this study, MODIS AOD data from the Terra and Aqua satellites were corrected with aerosol extinction profiles and relative humidity data. PBLH (Planetary Boundary Layer Height) was determined from MPLNET lidar-derived aerosol extinction coefficient profiles. Through statistical analysis, better agreement in correlation (R = 0.82) between the hourly PM10 concentration and hourly average Sunphotometer AOD was the obtained when vertical fraction method (VFM) considering Haze Layer Height (HLH) and hygroscopic growth factor f(RH) was used. The validity of the derived relationship between satellite AOD and surface PM10 concentration clearly demonstrates that satellite AOD data can be utilized for remote sensing of spatial distribution of regional PM10 concentration.

  12. Global View of Aerosol Vertical Distributions from CALIPSO Lidar Measurements and GOCART Simulations: Regional and Seasonal Variations

    NASA Technical Reports Server (NTRS)

    Yu, Hongbin; Chin, Mian; Winker, David M.; Omar, Ali H.; Liu, Zhaoyan; Kittaka, Chieko; Diehl, Thomas

    2010-01-01

    This study examines seasonal variations of the vertical distribution of aerosols through a statistical analysis of the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) lidar observations from June 2006 to November 2007. A data-screening scheme is developed to attain good quality data in cloud-free conditions, and the polarization measurement is used to separate dust from non-dust aerosol. The CALIPSO aerosol observations are compared with aerosol simulations from the Goddard Chemistry Aerosol Radiation Transport (GOCART) model and aerosol optical depth (AOD) measurements from the MODerate resolution Imaging Spectroradiometer (MODIS). The CALIPSO observations of geographical patterns and seasonal variations of AOD are generally consistent with GOCART simulations and MODIS retrievals especially near source regions, while the magnitude of AOD shows large discrepancies in most regions. Both the CALIPSO observation and GOCART model show that the aerosol extinction scale heights in major dust and smoke source regions are generally higher than that in industrial pollution source regions. The CALIPSO aerosol lidar ratio also generally agrees with GOCART model within 30% on regional scales. Major differences between satellite observations and GOCART model are identified, including (1) an underestimate of aerosol extinction by GOCART over the Indian sub-continent, (2) much larger aerosol extinction calculated by GOCART than observed by CALIPSO in dust source regions, (3) much weaker in magnitude and more concentrated aerosol in the lower atmosphere in CALIPSO observation than GOCART model over transported areas in midlatitudes, and (4) consistently lower aerosol scale height by CALIPSO observation than GOCART model. Possible factors contributing to these differences are discussed.

  13. A sensitivity study on the retrieval of aerosol vertical profiles using the oxygen A-band

    NASA Astrophysics Data System (ADS)

    Colosimo, S. F.; Natraj, V.; Sander, S. P.; Stutz, J.

    2015-11-01

    Atmospheric absorption in the O2 A-band (12 950-13 200 cm-1) offers a unique opportunity to retrieve aerosol extinction profiles from space-borne measurements due to the large dynamic range of optical thickness in that spectral region. Absorptions in strong O2 lines are saturated; therefore, any radiance measured in these lines originates from scattering in the upper part of the atmosphere. Outside of O2 lines, or in weak lines, the atmospheric column absorption is small, and light penetrates to lower atmospheric layers, allowing for the quantification of aerosols and other scatterers near the surface. While the principle of aerosol profile retrieval using O2 A-band absorption from space is well known, a thorough quantification of the information content, i.e., the amount of vertical profile information that can be obtained, and the dependence of the information content on the spectral resolution of the measurements, has not been thoroughly conducted. Here, we use the linearized vector radiative transfer model VLIDORT to perform spectrally resolved simulations of atmospheric radiation in the O2 A-band in the presence of aerosol for four different generic scenarios: Urban, Highly polluted, Elevated layer, and Marine-Arctic. The high-resolution radiances emerging from the top of the atmosphere are degraded to different spectral resolutions, simulating spectrometers with different resolving powers. We use optimal estimation theory to quantify the information content in the aerosol profile retrieval with respect to different aerosol parameters and instrument spectral resolutions. The simulations show that better spectral resolution generally leads to an increase in the total amount of information that can be retrieved, with the number of degrees of freedom (DoF) varying between 0.34-2.11 at low resolution (5 cm-1) to 3.43-5.92 at high resolution (0.05 cm-1) for the four different cases. A particularly strong improvement was found in the retrieval of tropospheric

  14. Vertical structure of recent Arctic warming.

    PubMed

    Graversen, Rune G; Mauritsen, Thorsten; Tjernström, Michael; Källén, Erland; Svensson, Gunilla

    2008-01-01

    Near-surface warming in the Arctic has been almost twice as large as the global average over recent decades-a phenomenon that is known as the 'Arctic amplification'. The underlying causes of this temperature amplification remain uncertain. The reduction in snow and ice cover that has occurred over recent decades may have played a role. Climate model experiments indicate that when global temperature rises, Arctic snow and ice cover retreats, causing excessive polar warming. Reduction of the snow and ice cover causes albedo changes, and increased refreezing of sea ice during the cold season and decreases in sea-ice thickness both increase heat flux from the ocean to the atmosphere. Changes in oceanic and atmospheric circulation, as well as cloud cover, have also been proposed to cause Arctic temperature amplification. Here we examine the vertical structure of temperature change in the Arctic during the late twentieth century using reanalysis data. We find evidence for temperature amplification well above the surface. Snow and ice feedbacks cannot be the main cause of the warming aloft during the greater part of the year, because these feedbacks are expected to primarily affect temperatures in the lowermost part of the atmosphere, resulting in a pattern of warming that we only observe in spring. A significant proportion of the observed temperature amplification must therefore be explained by mechanisms that induce warming above the lowermost part of the atmosphere. We regress the Arctic temperature field on the atmospheric energy transport into the Arctic and find that, in the summer half-year, a significant proportion of the vertical structure of warming can be explained by changes in this variable. We conclude that changes in atmospheric heat transport may be an important cause of the recent Arctic temperature amplification.

  15. Seasonal variations of aerosol optical properties, vertical distribution and associated radiative effects in the Yangtze Delta region of China

    NASA Astrophysics Data System (ADS)

    Liu, Jianjun; Zheng, Youfei; Li, Zhanqing; Flynn, Connor; Cribb, Maureen

    2012-08-01

    Four years of columnar aerosol optical properties and a one-year vertical profiles of aerosol particle extinction coefficient at 527 nm are analyzed at Taihu in the central Yangtze River Delta region in eastern China. Seasonal variations of aerosol optical properties, vertical distribution, and influence on shortwave radiation and heating rates were investigated. Multiyear variations of aerosol optical depths (AOD), Ångstrom exponents, single scattering albedo (SSA) and asymmetry factor (ASY) are analyzed, together with the vertical profile of aerosol extinction. AOD is largest in summer and smallest in winter. SSAs exhibit weak seasonal variation with the smallest values occurring during winter and the largest during summer. The vast majority of aerosol particles are below 2 km, and about 62%, 67%, 67% and 83% are confined to below 1 km in spring, summer, autumn and winter, respectively. Five-day back trajectory analyses show that the some aerosols aloft are traced back to northern/northwestern China, as far as Mongolia and Siberia, in spring, autumn and winter. The presence of dust aerosols were identified based on the linear depolarization measurements together with other information (i.e., back trajectory, precipitation, aerosol index). Dust strongly impacts the vertical particle distribution in spring and autumn, with much smaller effects in winter. The annual mean aerosol direct shortwave radiative forcing (efficiency) at the bottom, top and within the atmosphere are -34.8 ± 9.1 (-54.4 ± 5.3), -8.2 ± 4.8 (-13.1 ± 1.5) and 26.7 ± 9.4 (41.3 ± 4.6) W/m2 (Wm-2 τ-1), respectively. The mean reduction in direct and diffuse radiation reaching surface amount to 109.2 ± 49.4 and 66.8 ± 33.3 W/m2, respectively. Aerosols significantly alter the vertical profile of solar heating, with great implications for atmospheric stability and dynamics within the lower troposphere.

  16. A new method for evaluating the impact of vertical distribution on aerosol radiative forcing in general circulation models

    NASA Astrophysics Data System (ADS)

    Vuolo, M. R.; Schulz, M.; Balkanski, Y.; Takemura, T.

    2013-07-01

    The quantification and understanding of direct aerosol forcing is essential in the study of climate. One of the main issues that makes its quantification difficult is the lack of a complete comprehension of the role of the aerosol and clouds vertical distribution. This work aims at reducing the incertitude of aerosol forcing due to the vertical superposition of several short-lived atmospheric components, in particular different aerosols species and clouds. We propose a method to quantify the contribution of different parts of the atmospheric column to the forcing, and to evaluate model differences by isolating the effect of radiative interactions only. Any microphysical or thermo-dynamical interactions between aerosols and clouds are deactivated in the model, to isolate the effects of radiative flux coupling. We investigate the contribution of aerosol above, below and in clouds, by using added diagnostics in the aerosol-climate model LMDz. We also compute the difference between the forcing of the ensemble of the aerosols and the sum of the forcings from individual species, in clear-sky. This difference is found to be moderate on global average (14%) but can reach high values regionally (up to 100%). The non-additivity of forcing already for clear-sky conditions shows, that in addition to represent well the amount of individual aerosol species, it is critical to capture the vertical distribution of all aerosols. Nonlinear effects are even more important when superposing aerosols and clouds. Four forcing computations are performed, one where the full aerosol 3-D distribution is used, and then three where aerosols are confined to regions above, inside and below clouds respectively. We find that the forcing of aerosols depends crucially on the presence of clouds and on their position relative to that of the aerosol, in particular for black carbon (BC). We observe a strong enhancement of the forcing of BC above clouds, attenuation for BC below clouds, and a moderate

  17. Studying the vertical aerosol extinction coefficient by comparing in situ airborne data and elastic backscatter lidar

    NASA Astrophysics Data System (ADS)

    Rosati, Bernadette; Herrmann, Erik; Bucci, Silvia; Fierli, Federico; Cairo, Francesco; Gysel, Martin; Tillmann, Ralf; Größ, Johannes; Gobbi, Gian Paolo; Di Liberto, Luca; Di Donfrancesco, Guido; Wiedensohler, Alfred; Weingartner, Ernest; Virtanen, Annele; Mentel, Thomas F.; Baltensperger, Urs

    2016-04-01

    Vertical profiles of aerosol particle optical properties were explored in a case study near the San Pietro Capofiume (SPC) ground station during the PEGASOS Po Valley campaign in the summer of 2012. A Zeppelin NT airship was employed to investigate the effect of the dynamics of the planetary boundary layer at altitudes between ˜ 50 and 800 m above ground. Determined properties included the aerosol particle size distribution, the hygroscopic growth factor, the effective index of refraction and the light absorption coefficient. The first three parameters were used to retrieve the light scattering coefficient. Simultaneously, direct measurements of both the scattering and absorption coefficient were carried out at the SPC ground station. Additionally, a single wavelength polarization diversity elastic lidar system provided estimates of aerosol extinction coefficients using the Klett method to accomplish the inversion of the signal, for a vertically resolved comparison between in situ and remote-sensing results. Note, however, that the comparison was for the most part done in the altitude range where the overlap function is incomplete and accordingly uncertainties are larger. First, the airborne results at low altitudes were validated with the ground measurements. Agreement within approximately ±25 and ±20 % was found for the dry scattering and absorption coefficient, respectively. The single scattering albedo, ranged between 0.83 and 0.95, indicating the importance of the absorbing particles in the Po Valley region. A clear layering of the atmosphere was observed during the beginning of the flight (until ˜ 10:00 LT - local time) before the mixing layer (ML) was fully developed. Highest extinction coefficients were found at low altitudes, in the new ML, while values in the residual layer, which could be probed at the beginning of the flight at elevated altitudes, were lower. At the end of the flight (after ˜ 12:00 LT) the ML was fully developed, resulting in

  18. Influence of the vertical absorption profile of mixed Asian dust plumes on aerosol direct radiative forcing over East Asia

    NASA Astrophysics Data System (ADS)

    Noh, Young Min; Lee, Kwonho; Kim, Kwanchul; Shin, Sung-Kyun; Müller, Detlef; Shin, Dong Ho

    2016-08-01

    We estimate the aerosol direct radiative forcing (ADRF) and heating rate profiles of mixed East Asian dust plumes in the solar wavelength region ranging from 0.25 to 4.0 μm using the Santa Barbara Discrete Ordinate Atmospheric Radiative Transfer (SBDART) code. Vertical profiles of aerosol extinction coefficients and single-scattering albedos (SSA) were derived from measurements with a multi-wavelength Raman lidar system. The data are used as input parameters for our radiative transfer calculations. We considered four cases of radiative forcing in SBDART: 1. dust, 2. pollution, 3. mixed dust plume and the use of vertical profiles of SSA, and 4. mixed dust plumes and the use of column-averaged values of SSA. In our sensitivity study we examined the influence of SSA and aerosol layer height on our results. The ADRF at the surface and in the atmosphere shows a small dependence on the specific shape of the aerosol extinction vertical profile and its light-absorption property for all four cases. In contrast, at the top of the atmosphere (TOA), the ADRF is largely affected by the vertical distribution of the aerosols extinction. This effect increases if the light-absorption capacity (decrease of SSA) of the aerosols increases. We find different radiative effects in situations in which two layers of aerosols had different light-absorption properties. The largest difference was observed at the TOA for an absorbing aerosol layer at high altitude in which we considered in one case the vertical profile of SSA and in another case the column-averaged SSA only. The ADRF at the TOA increases when the light-absorbing aerosol layer is located above 3 km altitude. The differences between height-resolved SSA, which can be obtained from lidar data, and total layer-mean SSA indicates that the use of a layer-mean SSA can be rather misleading as it can induce a large error in the calculation of the ADRF at the TOA, which in turn may cause errors in the vertical profiles of heating rates.

  19. The vertical structure of limb hazes in the Martian atmosphere

    NASA Technical Reports Server (NTRS)

    Jaquin, Fred; Gierasch, Peter; Kahn, Ralph

    1986-01-01

    Vertical distribution and reflectance properties of aerosols in the Martian atmosphere are presented, based on Viking Orbiter images containing the planetary limb. Profiles of scattered light above the limb are used to constrain the temporal and spatial behavior of the aerosols. The data cover a wide range of seasons, locations, and viewing geometries. The typical atmospheric column contains one or more discrete, optically thin, ice-like haze layers between 30 and 90 km elevation, depending on the season, whose composition is inferred to be water ice. Below the detached hazes there is a continuous haze extending to the surface. The continuous haze is rarely above 50 km and is much redder in color than the detached hazes above, implying a composition that has a strong dust component. The aerosol distribution exhibits solid seasonal control inferred to be driven by the variable solar flux around the orbit of Mars.

  20. Titan's Aerosol and Stratospheric Ice Opacities Between 18 and 500 Micrometers: Vertical and Spectral Characteristics from Cassini CIRS

    NASA Technical Reports Server (NTRS)

    Anderson, Carrie M.; Samuelson, Robert E.

    2011-01-01

    Vertical distributions and spectral characteristics of Titan's photochemical aerosol and stratospheric ices are determined between 20 and 560 per centimeter (500-18 micrometers) from the Cassini Composite Infrared Spectrometer (CIRS). Results are obtained for latitudes of 15 N, 15 S, and 58 S, where accurate temperature profiles can be independently determined. In addition, estimates of aerosol and ice abundances at 62 N relative to those at 15 S are derived. Aerosol abundances are comparable at the two latitudes, but stratospheric ices are approximately 3 times more abundant at 62 N than at 15 S. Generally, nitrile ice clouds (probably HCN and HC3N), as inferred from a composite emission feature at approximately 160 per centimeter, appear to be located over a narrow altitude range in the stratosphere centered at approximately 90 km. Although most abundant at high northern latitudes, these nitrile ice clouds extend down through low latitudes and into mid southern latitudes, at least as far as 58 S. There is some evidence of a second ice cloud layer at approximately 60 km altitude at 58 S associated with an emission feature at approximately 80 per centimeter. We speculate that the identify of this cloud may be due to C2H6 ice, which in the vapor phase is the most abundant hydrocarbon (next to CH4) in the stratosphere of Titan. Unlike the highly restricted range of altitudes (50-100 km) associated with organic condensate clouds, Titan's photochemical aerosol appears to be well-mixed from the surface to the top of the stratosphere near an altitude of 300 km, and the spectral shape does not appear to change between 15 N and 58 S latitude. The ratio of aerosol-to-gas scale heights range from 1.3-2.4 at about 160 km to 1.1-1.4 at 300 km, although there is considerable variability with latitude, The aerosol exhibits a very broad emission feature peaking at approximately 140 per centimeter. Due to its extreme breadth and low wavenumber, we speculate that this feature may

  1. Long-range transport and vertical structure of Asian dust from CALIPSO and surface measurements during PACDEX

    NASA Astrophysics Data System (ADS)

    Huang, Jianping; Minnis, Patrick; Chen, Bin; Huang, Zhongwei; Liu, Zhaoyan; Zhao, Qingyun; Yi, Yuhong; Ayers, J. Kirk

    2008-12-01

    Knowledge of long-range transport and vertical distribution of Asian dust aerosols in the free troposphere is important for estimating their impact on climate. Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), surface micropulse lidar (MPL), and standard surface measurements are used to directly observe the long-range transport and vertical distribution of Asian dust aerosols in the free troposphere during the Pacific Dust Experiment (PACDEX). The MPL measurements were made at the Loess Plateau (35.95°N, 104.1°E) near the major dust source regions of the Taklamakan and Gobi deserts. Dust events are more frequent in the Taklamakan, where floating dust dominates, while more intensive, less frequent dust storms are more common in the Gobi region. The vertical distribution of the CALIPSO backscattering/depolarization ratios indicate that nonspherically shaped dust aerosols floated from near the ground to an altitude of approximately 9 km around the source regions. This suggests the possible long-range transport of entrained dust aerosols via upper tropospheric westerly jets. A very distinct large depolarization layer was also identified between 8 and 10 km over eastern China and the western Pacific Ocean corresponding to dust aerosols transported from the Taklamakan and Gobi areas, as confirmed by back trajectory analyses. The combination of these dust sources results in a two-layer or multilayered dust structure over eastern China and the western Pacific Ocean.

  2. A sensitivity study on the retrieval of aerosol vertical profiles using the oxygen A-band

    NASA Astrophysics Data System (ADS)

    Fedele Colosimo, Santo; Natraj, Vijay; Sander, Stanley P.; Stutz, Jochen

    2016-04-01

    Atmospheric absorption in the O2 A-band (12 950-13 200 cm-1) offers a unique opportunity to retrieve aerosol extinction profiles from space-borne measurements due to the large dynamic range of optical thickness in that spectral region. Absorptions in strong O2 lines are saturated; therefore, any radiance measured in these lines originates from scattering in the upper part of the atmosphere. Outside of O2 lines, or in weak lines, the atmospheric column absorption is small, and light penetrates to lower atmospheric layers, allowing for the quantification of aerosols and other scatterers near the surface.

    While the principle of aerosol profile retrieval using O2 A-band absorption from space is well-known, a thorough quantification of the information content, i.e., the amount of vertical profile information that can be obtained, and the dependence of the information content on the spectral resolution of the measurements, has not been thoroughly conducted. Here, we use the linearized vector radiative transfer model VLIDORT to perform spectrally resolved simulations of atmospheric radiation in the O2 A-band for four different aerosol extinction profile scenarios: urban (urban-rural areas), highly polluted (megacity areas with large aerosol extinction), elevated layer (identifying elevated plumes, for example for biomass burning) and low extinction (representative of small aerosol extinction, such as vegetated, marine and arctic areas). The high-resolution radiances emerging from the top of the atmosphere measurements are degraded to different spectral resolutions, simulating spectrometers with different resolving powers. We use optimal estimation theory to quantify the information content in the aerosol profile retrieval with respect to different aerosol parameters and instrument spectral resolutions. The simulations show that better spectral resolution generally leads to an increase in the total amount of information that can be retrieved, with the number of

  3. Measurements of Vertical Profiles of Turbulence, Temperature, Ozone, Aerosols, and BrO over Sea Ice and Tundra Snowpack during BROMEX

    NASA Astrophysics Data System (ADS)

    Shepson, P.; Caulton, D.; Cambaliza, M. L.; Dhaniyala, S.; Fuentes, J. D.; General, S.; Halfacre, J. W.; Nghiem, S. V.; Perez Perez, L.; Peterson, P. K.; Platt, U.; Pohler, D.; Pratt, K. A.; Simpson, W. R.; Stirm, B.; Walsh, S. J.; Zielcke, J.

    2012-12-01

    During the BROMEX field campaign of March 2012, we conducted measurements of boundary layer structure, ozone, BrO and aerosol, from a light, twin-engine aircraft during eleven flights originating from Barrow, AK. Flights were conducted over the sea ice in the Beaufort and Chukchi Seas, and over the tundra from Barrow to the Brooks Range, with vertical profiles covering altitudes from the surface to 3.5km in the free troposphere. Flights over the course of one month allowed a variety of sea ice conditions, including open water, nilas, first year sea ice, and frost flowers, to be examined over the Chukchi Sea. Atmospheric turbulence was measured using a calibrated turbulence probe, which will enable characterization of both the structure and turbulence of the Arctic boundary layer. Ozone was measured using a 2B UV absorption instrument. A GRIMM optical particle counter was used to measure 0.25-4 μm sized aerosol particles. The MAX-DOAS instrument enabled measurements of BrO vertical profiles. The aircraft measurements can be used to connect the surface measurements of ozone and BrO from the "Icelander" buoys, and the surface sites at Barrow, with those measured on the aircraft. Here we will discuss the spatial variability/coherence in these data. A major question that will be addressed using these data is the extent to which bromine is activated through reactions at the snowpack/ice surface versus the surface of aerosols. Here we will present a preliminary analysis of the relationships between snow/ice surface types, aerosol size-resolved number concentrations, and the vertical profiles of ozone and BrO.

  4. Vertical distribution of near-ground aerosol backscattering coefficient measured by a CCD side-scattering lidar

    NASA Astrophysics Data System (ADS)

    Tao, Zongming; Liu, Dong; Ma, Xiaomin; Shi, Bo; Shan, Huihui; Zhao, Ming; Xie, Chenbo; Wang, Yingjian

    2015-09-01

    The near-ground aerosols have the most impact on the human beings. Its fine spatial and temporal distribution, with which the environmental and meteorological departments concern themselves most, has not been elaborated very well due to the unavailable measurement tools. We present the continuous observations of the vertical profile of near-ground aerosol backscattering coefficients by employing our self-developed side-scattering lidar system based on charge-coupled device camera. During the experimental period from April 2013 to August 2014, four catalogs of aerosol backscattering coefficient profiles are found in the near ground. The continuous measurement is revealed by the contour plots measured during the whole night. These experimental results indicate that the aerosol backscattering coefficients in near ground are inhomogeneous and vary with altitude and time, which are very useful for the model researchers to study the regional air pollution and its climate impact.

  5. Vertical distribution of dimethylsulfide, sulfur dioxide, aerosol ions, and radon over the northeast Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Andreae, M. O.; Berresheim, H.; Andreae, T. W.; Kritz, M. A.; Bates, T. S.

    1988-01-01

    The vertical distributions, in temperate latitudes, of dimethylsulfide (DMS), SO2, radon, methanesulfonate (MSA), nonsea-salt sulfate (nss-sulfate), and aerosol Na(+), NH4(+), and NO(-) ions were determined in samples collected by an aircraft over the northeast Pacific Ocean during May 3-12, 1985. DMS was also determined in surface seawater. It was found that DMS concentrations, both in seawater and in the atmospheric boundary layer, were significantly lower than the values reported previously for subtropical and tropical regions, reflecting the seasonal variability in the temperate North Pacific. The vertical profiles of DMS, MSA, SO2, and nss-sulfate were found to be strongly dependent on the convective stability of the atmosphere and on air mass origin. Biogenic sulfur emissions could account for most of the sulfur budget in the boundary layer, while the long-range transport of continentally derived air masses was mainly responsible for the elevated levels of both SO2 and nss-sulfate in the free troposphere.

  6. Temporal Variations in the Vertical Structure of Jupiter's Atmosphere

    NASA Astrophysics Data System (ADS)

    Chanover, Nancy Janet

    1997-11-01

    We present models of Jupiter's center-to-limb reflectivity at wavelengths ranging from the near-ultraviolet to the near-infrared, the largest wavelength range ever used in such an analysis. In particular, we modeled center-to-limb scans of four latitudes using a multi-layered model of Jupiter's atmospheric vertical structure. Modeling Jupiter's center-to-limb reflectivity in methane absorption bands of different strengths allows us to probe the optical depths of the different gas layers. Modeling at continuum wavelengths yields information about the haze and cloud layers. The imaging data were collected using the Apache Point Observatory 3.5 meter telescope, the New Mexico State University 0.6 meter telescope, and the Hubble Space Telescope. Our standard model for the jovian atmospheric structure consists of two cloud decks and a stratospheric haze layer, all interleaved with aerosol-free gas layers. The radiative transfer code uses a doubling adding algorithm that performs a gradient search of the parameter space using a linearization of the fitting function. We added new opacity sources and the associated calculations to an existing program to adapt the model to our extended wavelength range. The model was also used to fit reflectivity variations of the convective plumes and adjacent dark regions in the north Equatorial Zone, at the latitude of the Galileo Probe entry. We find that the recovery time of Jupiter's atmosphere after a convective disturbance can be as long as seven years. Episodic events such as a South Equatorial Belt Disturbance can result in a variation in the ammonia cloud single scattering albedo and the optical depth of the stratospheric haze layer. Access to near-infrared wavelengths has allowed us to characterize the variability of the stratosphere for the first time. The stratospheric haze layer has its highest extent (not including the polar regions) above the northern Equatorial Zone. Active convection is likely the source of at least some

  7. Combining Passive Polarimetric and Lidar Observations from TCAP to Vertically Partition a Multi-Modal Aerosol Model

    NASA Astrophysics Data System (ADS)

    Cairns, B.; Ottaviani, M.; Knobelspiesse, K. D.; Chowdhary, J.; Hostetler, C. A.; Ferrare, R. A.; Hair, J. W.; Cook, A. L.; Harper, D. B.; Mack, T. L.; Hare, R. J.; Cleckner, C. S.; Rogers, R.; Mueller, D.; Burton, S. P.; Obland, M. D.; Scarino, A. J.; Redemann, J.; Schmid, B.; Fast, J. D.; Berg, L. K.

    2012-12-01

    The first airborne deployment associated with the Two-Column Aerosol Project (TCAP) field campaign was carried out on Cape Cod, Massachusetts during July 2012 using the DOE Gulfstream 1 (G-1) and the NASA Langley B200. The first column located on Cape Cod has the surface based ARM Mobile Facility, which measures aerosol properties, radiation, and cloud characteristics, as its anchor point. The second column, 200 km to the East, was chosen to facilitate characterization of the large gradient of AOD near the coast of New England. The G-1 was equipped with a suite of in situ instrumentation to measure the size, composition and optics of aerosols, together with spectral Aerosol Optical Depth (AOD) above the aircraft using the Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research. The G1 generally flew at low altitude except when profiling the two columns. The B200, flew at ~ 9 km, above the G1, and operated the world's first airborne three backscatter (355, 532 and 1064 nm) and two extinction (355 and 532 nm) channel high-spectral-resolution lidar, HSRL-2 and the Research Scanning Polarimeter (RSP), which provides multi-angle multi-spectral observations of the intensity and polarization over a spectral range from 410 to 2260 nm. The TCAP measurements are ideal for remote sensing of aerosols since a dark ocean allows the full power of the passive intensity and polarization observations to be explored. RSP observations over the ocean have previously been used to retrieve the AOD, particle size and complex refractive index of aerosols, but it was noted that the vertical distribution of the aerosols could affect the accuracy of the retrieval. In this paper we combine HSRL-2 and RSP data to retrieve and partition a multi-modal aerosol model through the column. The lidar intensive variables (ratios of the lidar observations) that do not depend on aerosol load are used to constrain the microphysics of the aerosol modes. Where the classification technique presented

  8. Observations of Dust Using the NASA Geoscience Laser Altimeter System (GLAS): New New Measurements of Aerosol Vertical Distribution From Space

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    On January 12, 2003 NASA launched the first satellite-based lidar, the Geoscience Laser -Altimeter System (GLAS), onboard the ICESat spacecraft. The GLAS atmospheric measurements introduce a fundamentally new and important tool for understanding the atmosphere and climate. In the past, aerosols have only been studied from space using images gathered by passive sensors. Analysis of this passive data has lead to an improved understanding of aerosol properties, spatial distribution, and their effect on the earth's climate. However, these images do not show the aerosol's vertical distribution. As a result, a key piece of information has been missing. The measurements now obtained by GLAS will provide information on the vertical distribution of aerosols and clouds, and improve our ability to study their transport processes and aerosol-cloud interactions. Here we show an overview of GLAS, provide an update of its current status, and present initial observations of dust profiles. In particular, a strategy of characterizing the height profile of dust plumes over source regions will be presented.

  9. Vertical profiles of aerosol and black carbon in the Arctic: a seasonal phenomenology along 2 years (2011-2012) of field campaigns

    NASA Astrophysics Data System (ADS)

    Ferrero, Luca; Cappelletti, David; Busetto, Maurizio; Mazzola, Mauro; Lupi, Angelo; Lanconelli, Christian; Becagli, Silvia; Traversi, Rita; Caiazzo, Laura; Giardi, Fabio; Moroni, Beatrice; Crocchianti, Stefano; Fierz, Martin; Močnik, Griša; Sangiorgi, Giorgia; Perrone, Maria G.; Maturilli, Marion; Vitale, Vito; Udisti, Roberto; Bolzacchini, Ezio

    2016-10-01

    We present results from a systematic study of vertical profiles of aerosol number size distribution and black carbon (BC) concentrations conducted in the Arctic, over Ny-Ålesund (Svalbard). The campaign lasted 2 years (2011-2012) and resulted in 200 vertical profiles measured by means of a tethered balloon (up to 1200 m a.g.l.) during the spring and summer seasons. In addition, chemical analysis of filter samples, aerosol size distribution and a full set of meteorological parameters were determined at ground. The collected experimental data allowed a classification of the vertical profiles into different typologies, which allowed us to describe the seasonal phenomenology of vertical aerosol properties in the Arctic. During spring, four main types of profiles were found and their behavior was related to the main aerosol and atmospheric dynamics occurring at the measuring site. Background conditions generated homogenous profiles. Transport events caused an increase of aerosol concentration with altitude. High Arctic haze pollution trapped below thermal inversions promoted a decrease of aerosol concentration with altitude. Finally, ground-based plumes of locally formed secondary aerosol determined profiles with decreasing aerosol concentration located at different altitude as a function of size. During the summer season, the impact from shipping caused aerosol and BC pollution plumes to be constrained close to the ground, indicating that increasing shipping emissions in the Arctic could bring anthropogenic aerosol and BC in the Arctic summer, affecting the climate.

  10. Multi-Summer Climatology of Cumuli at SGP site: Vertical Structure

    SciTech Connect

    Kassianov, Evgueni I.; Berg, Larry K.

    2011-10-01

    We perform a case study for estimating the impact of the vertical distribution of cloud fraction on the normalized cloud radiative forcing (CRF) using a decade-long (2000-2009) high resolution dataset of cloud macrophysical and radiative properties. This dataset is developed for fair-weather cumuli (FWC) observed at the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site. The design of the case study reduces effects associated with non-cloud factors, such as the diurnal changes of aerosol loading and solar zenith angle. The results of the case study suggest that the impact of the vertical cloud structure can be substantial. Therefore, taking into account the vertical distribution of clouds would be beneficial for more comprehensive parameterizations aimed to portray the complex interactions between clouds and radiation more accurately

  11. Optical and physical characteristics of Bay of Bengal aerosols during W-ICARB: Spatial and vertical heterogeneities in the marine atmospheric boundary layer and in the vertical column

    NASA Astrophysics Data System (ADS)

    Moorthy, K. Krishna; Beegum, S. Naseema; Babu, S. Suresh; Smirnov, Alexander; John, Sherine Rachel; Kumar, K. Raghavendra; Narasimhulu, K.; Dutt, C. B. S.; Nair, Vijayakumar S.

    2010-12-01

    Analysis of the continuous and collocated measurements of columnar spectral aerosol optical depths (AODs) and mass size distributions in the marine atmospheric boundary layer (MABL) over the Bay of Bengal (BoB), carried out from 27 December 2008 to 29 January 2009 during the Winter Integrated Campaign for Aerosols, Gases and Radiation Budget (W-ICARB), revealed distinct regional features in the spatial variations of the aerosol properties in the MABL and column. In general, AODs were high over the northern and northwestern parts of the BoB, with pockets of very high values, within which the AODs were as high as ˜0.8 while the smallest values (˜0.1) were observed over the northeastern BoB, off the Myanmar and Bangladesh coasts. Interestingly, though, this region had the highest Angstrom wavelength exponent α (˜1.5), notwithstanding the generally high values that prevailed over the eastern as well as northern coastal regions of India. Back trajectory analyses revealed the significant role of the advected aerosols in the observed spatial pattern. Within the MABL, high accumulation mode mass concentrations (MA) prevailed over the entire BoB with the accumulation fraction ranging from 0.6 to 0.95, whereas very high fine-mode (r < 0.1 μm) aerosol mass fractions (˜0.8) were observed over the northeastern and western coastal BoB adjoining the Indian mainland (where α was high to very high). The vertical distributions, inferred from the columnar and MABL properties as well as from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations data, revealed better homogeneity in the northeastern and eastern BoB, whereas significant heterogeneity was seen over other regions.

  12. The vertical structure of the Jovian atmosphere

    NASA Astrophysics Data System (ADS)

    Smith, P. H.

    1986-03-01

    The equatorial and tropical regions of Jupiter are presently treated in light of an inhomogeneous atmospheric model that encompasses both polarizing aerosols and methane gas, in keeping with Pioneer polarimetry and photometry data as well as the methane band data obtained by West (1979). The relative strengths of weak and strong methane bands are addressed by a two-cloud model with overlying stratospheric haze. For all the regions considered, the best fit for polarization measurements is a negatively polarizing ammonia cloud beneath a positively polarizing haze. Unlike the nearby features, the equatorial region and the Great Red Spot have a negative polarization at 80-deg phase angle, implying less gas above the clouds in these regions.

  13. Vertically resolved separation of dust and other aerosol types by a new lidar depolarization method.

    PubMed

    Luo, Tao; Wang, Zhien; Ferrare, Richard A; Hostetler, Chris A; Yuan, Renmin; Zhang, Damao

    2015-06-01

    This paper developed a new retrieval framework of external mixing of the dust and non-dust aerosol to predict the lidar ratio of the external mixing aerosols and to separate the contributions of non-spherical aerosols by using different depolarization ratios among dust, sea salt, smoke, and polluted aerosols. The detailed sensitivity tests and case study with the new method showed that reliable dust information could be retrieved even without prior information about the non-dust aerosol types. This new method is suitable for global dust retrievals with satellite observations, which is critical for better understanding global dust transportation and for model improvements. PMID:26072778

  14. The vertical structure of Arctic haze as determined from airborne net-flux radiometer measurements

    NASA Technical Reports Server (NTRS)

    Ackerman, T. P.; Valero, F. P. J.

    1984-01-01

    From net-flux radiometer measurements and model results, the vertical layer structure is deduced of the Arctic haze encountered during two of the AGASP flights. The total value of the absorption optical depth is found to be on the order of 0.065 for both flights, with the majority of the absorbing aerosol concentrated in the lowest 1.6 km of the atmosphere. A comparison of these results with measurements of the carbon concentration leads to a value of the specific absorption of carbon of 24 sq m g. While higher than expected, this value is shown to be consistent with an internally-mixed aerosol of carbon cores and sulfate shells.

  15. Results of a comprehensive atmospheric aerosol-radiation experiment in the southwestern United States. I - Size distribution, extinction optical depth and vertical profiles of aerosols suspended in the atmosphere. II - Radiation flux measurements and

    NASA Technical Reports Server (NTRS)

    Deluisi, J. J.; Furukawa, F. M.; Gillette, D. A.; Schuster, B. G.; Charlson, R. J.; Porch, W. M.; Fegley, R. W.; Herman, B. M.; Rabinoff, R. A.; Twitty, J. T.

    1976-01-01

    Results are reported for a field test that was aimed at acquiring a sufficient set of measurements of aerosol properties required as input for radiative-transfer calculations relevant to the earth's radiation balance. These measurements include aerosol extinction and size distributions, vertical profiles of aerosols, and radiation fluxes. Physically consistent, vertically inhomogeneous models of the aerosol characteristics of a turbid atmosphere over a desert and an agricultural region are constructed by using direct and indirect sampling techniques. These results are applied for a theoretical interpretation of airborne radiation-flux measurements. The absorption term of the complex refractive index of aerosols is estimated, a regional variation in the refractive index is noted, and the magnitude of solar-radiation absorption by aerosols and atmospheric molecules is determined.

  16. Comparing Water Vapor Mixing Ratio Profiles and Cloud Vertical Structure from Multiwavelength Raman Lidar Retrievals and Radiosounding Measurements

    NASA Astrophysics Data System (ADS)

    Costa-Surós, Montserrat; Stachlewska, Iwona S.; Markowicz, Krzysztof

    2016-06-01

    A study of comparison of water vapor mixing ratio profiles, relative humidity profiles, and cloud vertical structures using two different instruments, a multiwavelength Aerosol-Depolarization-Raman lidar and radiosoundings, is presented. The observations were taken by the lidar located in Warsaw center and the radiosoundings located about 30km to the North in Legionowo (Poland). We compared the ground-based remote sensing technology with in-situ method in order to improve knowledge about water content thought the atmosphere and cloud formation. The method used for retrieving the cloud vertical structure can be improved comparing the radiosonde results with the lidar observations, which show promising results.

  17. The potential of LIRIC to validate the vertical profiles of the aerosol mass concentration estimated by an air quality model

    NASA Astrophysics Data System (ADS)

    Siomos, Nikolaos; Filoglou, Maria; Poupkou, Anastasia; Liora, Natalia; Dimopoulos, Spyros; Melas, Dimitris; Chaikovsky, Anatoli; Balis, Dimitris

    2015-04-01

    Vertical profiles of the aerosol mass concentration derived by a retrieval algorithm that uses combined sunphotometer and LIDAR data (LIRIC) were used in order to validate the mass concentration profiles estimated by the air quality model CAMx. LIDAR and CIMEL measurements of the Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki were used for this validation.The aerosol mass concentration profiles of the fine and coarse mode derived by CAMx were compared with the respective profiles derived by the retrieval algorithm. For the coarse mode particles, forecasts of the Saharan dust transportation model BSC-DREAM8bV2 were also taken into account. Each of the retrieval algorithm's profiles were matched to the models' profile with the best agreement within a time window of four hours before and after the central measurement. OPAC, a software than can provide optical properties of aerosol mixtures, was also employed in order to calculate the angstrom exponent and the lidar ratio values for 355nm and 532nm for each of the model's profiles aiming in a comparison with the angstrom exponent and the lidar ratio values derived by the retrieval algorithm for each measurement. The comparisons between the fine mode aerosol concentration profiles resulted in a good agreement between CAMx and the retrieval algorithm, with the vertical mean bias error never exceeding 7 μgr/m3. Concerning the aerosol coarse mode concentration profiles both CAMx and BSC-DREAM8bV2 values are severely underestimated, although, in cases of Saharan dust transportation events there is an agreement between the profiles of BSC-DREAM8bV2 model and the retrieval algorithm.

  18. Vertical Structure and Vertical Evolution of Halogen Activation Events Observed by Autonomous Buoys

    NASA Astrophysics Data System (ADS)

    Simpson, W. R.; Peterson, P.; Burd, J.

    2015-12-01

    Heterogeneous reactions on saline surfaces release reactive halogen species in the Arctic during late winter / spring (Feb--May). These reactive halogens drastically alter the photooxidative environment, removing ozone and oxidizing mercury and hydrocarbons. Both the snowpack and suspended particles / blowing snow possess surfaces that can sustain this chemistry, leading to variations in reactive halogen vertical profiles and temporal evolution of those profiles. This chemistry also occurs in a typically stable (inverted) atmospheric structure that hinders vertical mixing, limiting the vertical extent of snowpack influence. In this presentation, Multiple-AXis Differential Optical Absorption Spectroscopy (MAXDOAS) of bromine monoxide (BrO) along with optimal estimation inversions are used to measure the vertical structure of BrO. The effective mixing height of the BrO layer varies with atmospheric stability, and an event is shown where a shallow but highly concentrated layer of surface BrO encounters sea-ice-lead-induced convection that vertically mixes the BrO higher, initially diluting the surface concentration. Over time, the surface concentration recovers and the now thicker layer grows to a higher column density of BrO. Understanding of the relationship between BrO event intensity and meteorological situations can help to understand BrO chemistry and remote sensing and assist in prediction of how reactive halogens may respond to a changing Arctic climate.

  19. Continuous and automatic measurement of atmospheric structures and aerosols optical properties with R-Man510 nitrogen Raman lidar

    NASA Astrophysics Data System (ADS)

    Royer, P.; Renaudier, M.; Sauvage, L.; Boquet, M.; Thobois, L.; Bizard, A.

    2012-04-01

    A new compact and light nitrogen Raman lidar (R-Man510) has recently been developed by Leosphere company. This UV-lidar system is based on a low energy diode pumped Nd:YAG laser at 355 nm and has been developed to be operated unmanly for the meteorological and airport needs. Measurements are typically performed with a vertical resolution between 15 and 60 m and a temporal resolution between 30 seconds (for elastic channel) and 10 minutes (for Raman channel). The elastic channel of the lidar is used to automatically detect up to 9 atmospheric structures (Plantery Boundary Layer height, aerosol and cloud layers) in quasi real-time. Aerosols are classified in 6 types (pollution aerosols, desert dusts, volcanic ashes, marine aerosols, biomass burning and no aerosols) considering informations on depolarization ratio determined with the two cross-polarized elastic channels and on aerosols optical properties (extinction-to-backscatter ratio, aerosol backscatter and extinction coefficients) determined thanks to the nitrogen Raman channel at 387 nm. Aerosols optical properties can then been used for the assessment of mass concentrations which is crucial in case of hypothetical volcanic eruption. We will present the first results obtained with this new commercial lidar system. Daytime and nighttime performances of the system will be analyzed and compared with simulations from an instrumental model.

  20. Vertical profiling of marine aerosol, dust and their mixtures utilizing the synergy of sunphotometer and lidar measurements

    NASA Astrophysics Data System (ADS)

    Tsekeri, Alexandra; Amiridis, Vassilis; Lopatin, Anton; Marinou, Eleni; Engelman, Ronny; Baars, Holger; Wandinger, Ulla; Ansmann, Albert; Solomos, Stavros; Dubovik, Oleg; Schüttemeyer, Dirk

    2015-04-01

    Current and future lidar products from space missions (CALIPSO, ADM-Aeolus, EarthCARE) aim to improve our understanding of atmospheric dynamics and aerosol/cloud interactions on global scale. However, the lidar instruments onboard these three missions (CALIOP, ALADIN, ATLID) are different systems, operating at different wavelengths and providing different sets of measured parameters. In order to spectrally homogenize the datasets, aerosol/cloud-type-dependent spectral conversion factors are needed to be applied to all lidar-related properties (extinction, backscatter and depolarization), based on the aerosol/cloud classification of the space-borne observations. The well-established European Aerosol Research Lidar Network (EARLINET) offers the unique opportunity to support such an effort. However, EARLINET database suffers from lack of information for specific aerosol types such as marine and mixed dust/marine cases. Unfortunately, these types are not observed in EARLINET's core stations, since the stations are mostly located at continental sites and are influenced by urban pollution. Moreover, the lidar systems near the coastlines suffer from the inability to measure at the first few hundred meters (500-1000 m) due to their technical design, which results in an incomplete laser/telescope overlap region. Towards the study of marine and marine-dust aerosol mixtures we organized the experimental campaign of "Characterization of Aerosol mixtures of Dust And Marine origin" (CHARADMexp), on June 20 to July 10, at Finokalia, Grete, Greece. Our aim was to derive optical, microphysical and chemical properties of the marine component and its mixtures with dust, employing sophisticated instrumentation installed on the site of Finokalia ACTRIS station, where only marine and dust particles are present 95% of the time. Specifically, aerosol characterization was established by the "Generalized Aerosol Retrieval from Radiometer and Lidar Combined data" (GARRLiC), a technique that

  1. Evaluation of modeled vertical aerosol distributions over east-Asia using in-situ and satellite data during summer 2008

    NASA Astrophysics Data System (ADS)

    Quennehen, Boris; Raut, Jean-Christophe; Law, Kathy S.; Thomas, Jennie L.; Ancellet, Gérard; Bazureau, Ariane; Daskalakis, Nikos; Kim, Sang-Woo; Yoon, Soon-Chang; Zhu, Tong; Pelon, Jacques

    2013-04-01

    As part of the EU ECLIPSE project, which aims to quantify the climate impact of short lived climate forcers (SLCFs), including aerosols, black carbon and ozone, regional models are being used to evaluate global model performance for specific case studies. Here, we present results using regional WRF-Chem simulations over east-Asia. Results are compared to data from field campaigns which took place in summer 2008 and from long-term measurement stations. This study will, in a first step, evaluate the ability of the model to simulate aerosol physical, chemical and optical properties, with a focus on pollution layers. In a second step, the radiative impact of such layers over east-Asia will be investigated as a function of their position relative to clouds. The WRF-Chem regional model was run using MOZART gas phase chemistry and the MOSAIC aerosol scheme and was evaluated against available measurements for the period August to September 2008. The model was run using ECLIPSE anthropogenic and GFEDv3.1 fire emissions for 2008, while initial and boundary conditions were specified from the TM4 global chemical transport model. The radiative impact of pollution aerosol layers has already been investigated but less is known about the influence of vertical layering in the atmosphere. Such layers might have different radiative impacts whether they are below or above clouds and in that sense, a better understanding of their spatial extent is critical. Information about pollution aerosol layers and clouds optical properties and positions over East-Asia are determined using observations from CALIPSO. The radiative impact of these layers is simulated and compared to the observations. In addition to satellite observations, model results are evaluated against trace gas and aerosol data from aircraft campaigns over eastern Asia in summer 2008 (e.g., CAREBEIJING and CAPMEX) and ground-based measurements (e.g., NIES and ABC). In this study, we assess aerosol total concentrations and size

  2. How Well Do State-of-the-Art Techniques Measuring the Vertical Profile of Tropospheric Aerosol Extinction Compare?

    SciTech Connect

    Schmid, Beat; Ferrare, Richard; Flynn, Connor M.; Elleman, Robert; Covert, David; Strawa, A.; Welton, E J.; Turner, David D.; Jonsson, Haf; Redemann, Jens; Eilers, J.; Ricci, K.; Hallar, A. G.; Clayton, M. B.; Michalsky, Joseph J.; Smirnov, A.; Holben, B. N.; Barnard, James C.

    2006-02-01

    The recent U.S. Department of Energy Atmospheric Radiation Measurements (ARM) Aerosol Intensive Observation Period (AIOP, May 2003) yielded one of the best measurement sets obtained to-date to assess our ability to measure the vertical profile of ambient aerosol extinction. During one month, a heavily instrumented aircraft with well characterized aerosol sampling ability carrying well proven and new aerosol instrumentation, devoted most of the 60 available flight hours to flying vertical profiles over the heavily instrumented ARM Southern Great Plains (SGP) Climate Research Facility (CRF). This allowed us to compare vertical extinction profiles obtained from 6 different instruments: airborne Sun photometer, airborne nephelometer/absorption photometer, airborne cavity ring-down system, ground-based Raman lidar and two ground-based elastic backscatter lidars. We find the in situ measurements to be biased low (2 - 4 Mm 1 equivalent to 12-17% in the visible, or 45% in the near-infrared) when compared to airborne sunphotometer extinction. On the other hand, we find that with respect to AATS-14, the lidar ?ep(?) are biased high. Bias differences are 0.004 Km-1 (13%) and 0.007 Km-1 (24%) for the two elastic back-scatter lidars (MPLARM and MPLNET, ? = 523 nm) and 0.029 Km-1 (54%) for the Raman lidar (? = 355 nm). An unnoticed loss of sensitivity of the Raman lidar had occurred leading up to AIOP and we expect better agreement from the recently restored system. Looking at the collective results from six field campaigns conducted since 1996, airborne in situ measurements of extinction tend to be biased slightly low (17% at visible wavelengths) when compared to airborne sunphotometer extinction. On the other hand, extinction derived from lidars tend to have no or positive biases. We conclude that the error associated with measuring the tropospheric vertical profile of the ambient aerosol extinction with current state-of-the art instrumentation is 15-20% at visible wavelengths

  3. How Well do State-of-the-Art Techniques Measuring the Vertical Profile of Tropospheric Aerosol Extinction Compare?

    NASA Technical Reports Server (NTRS)

    Schmid, B.; Ferrare, R.; Flynn, C.; Elleman, R.; Covert, D.; Strawa, A.; Welton, E.; Turner, D.; Jonsson, H.; Redemann, J.; Eilers, J.; Ricci, K.; Hallar, A. G.; Clayton, M.; Michalsky, J.; Smirnov, A.; Holben, B.; Barnard, J.

    2006-01-01

    The recent Department of Energy Atmospheric Radiation Measurement (ARM) Aerosol Intensive Operations Period (AIOP, May 2003) yielded one of the best measurement sets obtained to date to assess our ability to measure the vertical profile of ambient aerosol extinction sigma(ep)(lambda) in the lower troposphere. During one month, a heavily instrumented aircraft with well-characterized aerosol sampling ability carrying well-proven and new aerosol instrumentation devoted most of the 60 available flight hours to flying vertical profiles over the heavily instrumented ARM Southern Great Plains (SGP) Climate Research Facility (CRF). This allowed us to compare vertical extinction profiles obtained from six different instruments: airborne Sun photometer (AATS-14), airborne nephelometer/absorption photometer, airborne cavity ring-down system, groundbased Raman lidar, and two ground-based elastic backscatter lidars. We find the in situ measured sigma(ep)(lambda) to be lower than the AATS-14 derived values. Bias differences are 0.002-0.004 Km!1 equivalent to 13-17% in the visible, or 45% in the near-infrared. On the other hand, we find that with respect to AATS-14, the lidar sigma(ep)(lambda) are higher: Bias differences are 0.004 Km(-1) (13%) and 0.007 Km(-1) (24%) for the two elastic backscatter lidars (MPLNET and MPLARM, lambda = 523 nm) and 0.029 Km(-1) (54%) for the Raman lidar (lambda = 355 nm). An unnoticed loss of sensitivity of the Raman lidar had occurred leading up to AIOP, and we expect better agreement from the recently restored system. Looking at the collective results from six field campaigns conducted since 1996, airborne in situ measurements of sigma(ep)(lambda) tend to be biased slightly low (17% at visible wavelengths) when compared to airborne Sun photometer sigma(ep)(lambda). On the other hand, sigma(ep)(lambda) values derived from lidars tend to have no or positive biases. From the bias differences we conclude that the typical systematic error associated

  4. Evaluation of the aerosol vertical distribution in global aerosol models through comparison against CALIOP measurements: AeroCom phase II results

    NASA Astrophysics Data System (ADS)

    Koffi, Brigitte; Schulz, Michael; Bréon, François-Marie; Dentener, Frank; Steensen, Birthe Marie; Griesfeller, Jan; Winker, David; Balkanski, Yves; Bauer, Susanne E.; Bellouin, Nicolas; Berntsen, Terje; Bian, Huisheng; Chin, Mian; Diehl, Thomas; Easter, Richard; Ghan, Steven; Hauglustaine, Didier A.; Iversen, Trond; Kirkevâg, Alf; Liu, Xiaohong; Lohmann, Ulrike; Myhre, Gunnar; Rasch, Phil; Seland, Åyvind; Skeie, Ragnhild B.; Steenrod, Stephen D.; Stier, Philip; Tackett, Jason; Takemura, Toshihiko; Tsigaridis, Kostas; Vuolo, Maria Raffaella; Yoon, Jinho; Zhang, Kai

    2016-06-01

    The ability of 11 models in simulating the aerosol vertical distribution from regional to global scales, as part of the second phase of the AeroCom model intercomparison initiative (AeroCom II), is assessed and compared to results of the first phase. The evaluation is performed using a global monthly gridded data set of aerosol extinction profiles built for this purpose from the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) Layer Product 3.01. Results over 12 subcontinental regions show that five models improved, whereas three degraded in reproducing the interregional variability in Zα0-6 km, the mean extinction height diagnostic, as computed from the CALIOP aerosol profiles over the 0-6 km altitude range for each studied region and season. While the models' performance remains highly variable, the simulation of the timing of the Zα0-6 km peak season has also improved for all but two models from AeroCom Phase I to Phase II. The biases in Zα0-6 km are smaller in all regions except Central Atlantic, East Asia, and North and South Africa. Most of the models now underestimate Zα0-6 km over land, notably in the dust and biomass burning regions in Asia and Africa. At global scale, the AeroCom II models better reproduce the Zα0-6 km latitudinal variability over ocean than over land. Hypotheses for the performance and evolution of the individual models and for the intermodel diversity are discussed. We also provide an analysis of the CALIOP limitations and uncertainties contributing to the differences between the simulations and observations.

  5. Vertical Transport of Aerosol Particles across Mountain Topography near the Los Angeles Basin

    NASA Astrophysics Data System (ADS)

    Murray, J. J.; Schill, S.; Freeman, S.; Bertram, T. H.; Lefer, B. L.

    2015-12-01

    Transport of aerosol particles is known to affect air quality and is largely dependent on the characteristic topography of the surrounding region. To characterize this transport, aerosol number distributions were collected with an Ultra-High Sensitivity Aerosol Spectrometer (UHSAS, DMT) during the 2015 NASA Student Airborne Research Program (SARP) in and around the Los Angeles Basin in Southern California. Increases in particle number concentration and size were observed over mountainous terrain north of Los Angeles County. Chemical analysis and meteorological lagrangian trajectories suggest orographic lifting processes, known as the "chimney effect". Implications for spatial transport and distribution will be discussed.

  6. Atmospheric Vertical Structure at Skukuza, South Africa during the 1999 and 2000 SAFARI Dry-Season Campaigns

    NASA Astrophysics Data System (ADS)

    Greco, S.; Swap, R. J.; Stein, D. C.; Welton, J.; McGill, M.; Freiman, T.

    2001-12-01

    Data obtained during the 1999 and 2000 SAFARI Dry-Season campaigns are used to document and detail the atmospheric vertical structure at Skukuza, South Africa. The vertical structure is investigated using on-site radiosonde, ground-based Micro-pulse Lidar, and AERONET sun photometer data obtained at the Skukuza site in Kruger National Park. Data obtained from the Cloud Physics Lidar on board the NASA ER-2 and the satellite-based TOMS Aerosol Index are also used. Special attention is focused upon the boundary layer and its dynamics and the multiple stable layers throughout the atmospheric column. In addition to describing the vertical structure during both campaigns, both intra-seasonal for different weather regimes and inter-seasonal for 1999 compared to 2000, differences are investigated and evaluated.

  7. Continental pollution in the western Mediterranean basin: vertical profiles of aerosol and trace gases measured over the sea during TRAQA 2012 and SAFMED 2013

    NASA Astrophysics Data System (ADS)

    Di Biagio, C.; Doppler, L.; Gaimoz, C.; Grand, N.; Ancellet, G.; Raut, J.-C.; Beekmann, M.; Borbon, A.; Sartelet, K.; Attié, J.-L.; Ravetta, F.; Formenti, P.

    2015-08-01

    In this study we present airborne observations of aerosol and trace gases obtained over the sea in the western Mediterranean basin during the TRAQA (TRansport and Air QuAlity) and SAFMED (Secondary Aerosol Formation in the MEDiterranean) campaigns in summer 2012 and 2013. A total of 23 vertical profiles were measured up to 5000 m above sea level over an extended area (40-45° N and 2° W-12° E) including the Gulf of Genoa, southern France, the Gulf of Lion, and the Spanish coast. During TRAQA and SAFMED the study area experienced a wide range of meteorological conditions which favoured pollution export from different sources located around the basin. Also, several events of dust outflows were measured during the campaigns. Observations from the present study show that continental pollution largely affects the western Mediterranean both close to coastal regions and in the open sea as far as ~ 250 km from the coastline. The measured aerosol scattering coefficient varies between ~ 20 and 120 Mm-1, while carbon monoxide (CO) and ozone (O3) mixing ratios are in the range of 60-165 and 30-85 ppbv, respectively. Pollution reaches 3000-4000 m in altitude and presents a very complex and highly stratified structure characterized by fresh and aged layers both in the boundary layer and in the free troposphere. Within pollution plumes the measured particle concentration in the Aitken (0.004-0.1 μm) and accumulation (0.1-1.0 μm) modes is between ~ 30 and 5000-6000 scm-3 (standard cm-3), which is comparable to the aerosol concentration measured in continental areas under pollution conditions. Additionally, our measurements indicate the presence of highly concentrated Aitken layers (10 000-15 000 scm-3) observed both close to the surface and in the free troposphere, possibly linked to the influence of new particle formation (NPF) episodes over the basin.

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

    SciTech Connect

    Rosenfeld, Daniel

    2015-12-23

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

  9. The vertical structure and thickness of Saturn's rings

    NASA Technical Reports Server (NTRS)

    Cuzzi, J. N.; Burns, J. A.; Durisen, R. H.; Hamill, P. M.

    1979-01-01

    An explanation for the vertical structure and thickness of Saturn's rings compatible with observational data is presented. The model of the rings as being many particles thick is shown to be possible, with random particle motions preventing the complete flattening of the system and a gaussian distribution of particle density with vertical displacement. The model prediction of a maximum ring thickness of tens of meters, however, is in conflict with observations of ring thickness of at least 0.8 km at ring-plane passage. It is shown that perturbations to ring particle orbits caused by the sun and Saturn's large satellites may produce long- and short-period coherent vertical ring displacements and a nonlinear displacement of the ring plane from the equatorial plane with radial distance, leading to an apparent edge-on thickness of a few hundred meters.

  10. The Potential of The Synergy of Sunphotometer and Lidar Data to Validate Vertical Profiles of The Aerosol Mass Concentration Estimated by An Air Quality Model

    NASA Astrophysics Data System (ADS)

    Siomos, N.; Filioglou, M.; Poupkou, A.; Liora, N.; Dimopoulos, S.; Melas, D.; Chaikovsky, A.; Balis, D. S.

    2016-06-01

    Vertical profiles of the aerosol mass concentration derived by the Lidar/Radiometer Inversion Code (LIRIC), that uses combined sunphotometer and lidar data, were used in order to validate the aerosol mass concentration profiles estimated by the air quality model CAMx. Lidar and CIMEL measurements performed at the Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki, Greece (40.5N, 22.9E) from the period 2013-2014 were used in this study.

  11. The effect of vertical velocity probability distribution shape on cloud activation of aerosols: off-line calculations

    NASA Astrophysics Data System (ADS)

    Tonttila, J.; Romakkaniemi, S.; Räisänen, P.; Kokkola, H.; Järvinen, H.

    2012-04-01

    Off-line calculations of cloud activation of aerosols using a probability density function (PDF) for vertical velocity (w) are performed. The focus is on the variation of the shape of the PDF using two functional formulations: the Normal distribution PDF and the Pearson type IV PDF. The Normal distribution provides a familiar example, as it has been widely used to approximate vertical velocity distributions in numerous applications, including climate models. Pearson type IV distribution provides an alternative that, to our knowledge, has not been employed before to describe the vertical velocity PDF. The advantage of the Pearson distribution is its versatility in representing skewed and more peaked distribution shapes compared to the Normal distribution, though this is obtained at the expense of increased mathematical complexity. The experiments are performed using a box model, in which the environmental conditions, including the aerosol size distribution (bi-modal) and chemical composition (ammonium-sulphate particles) are prescribed as constants. Measured size distributions comprising clean and polluted cases are used. Cloud activation of aerosols is calculated by integrating over the positive side of the PDF of w, which yields the mean number of activated particles (Nact). The mean, variance, and skewness of the PDFs along with the type of the PDF itself are altered in order to explore the effect of the PDF shape on the activation process. All experiments are repeated for three well-documented activation parameterizations: Lin & Leaitch, Abdul-Razzak & Ghan and Fountoukis & Nenes. The results show that for symmetric distributions of w (skewness = 0) there is a maximum difference of 10-15 % in Nact between the cases with w given by the Normal distribution, and the more peaked Pearson distribution. The largest differences are seen for the most polluted cases. Nact in clean cases will saturate rather quickly with respect to the maximum supersaturation and, hence

  12. Improved parameterization for the vertical flux of dust aerosols emitted by an eroding soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The representation of the dust cycle in atmospheric circulation models hinges on an accurate parameterization of the vertical dust flux at emission. However, existing parameterizations of the vertical dust flux vary substantially in their scaling with wind friction velocity, require input parameters...

  13. Lidar-Radiometer Inversion Code (LIRIC) for the retrieval of vertical aerosol properties from combined lidar/radiometer data: development and distribution in EARLINET

    NASA Astrophysics Data System (ADS)

    Chaikovsky, A.; Dubovik, O.; Holben, B.; Bril, A.; Goloub, P.; Tanré, D.; Pappalardo, G.; Wandinger, U.; Chaikovskaya, L.; Denisov, S.; Grudo, Y.; Lopatin, A.; Karol, Y.; Lapyonok, T.; Amiridis, V.; Ansmann, A.; Apituley, A.; Allados-Arboledas, L.; Binietoglou, I.; Boselli, A.; D'Amico, G.; Freudenthaler, V.; Giles, D.; Granados-Muñoz, M. J.; Kokkalis, P.; Nicolae, D.; Oshchepkov, S.; Papayannis, A.; Perrone, M. R.; Pietruczuk, A.; Rocadenbosch, F.; Sicard, M.; Slutsker, I.; Talianu, C.; De Tomasi, F.; Tsekeri, A.; Wagner, J.; Wang, X.

    2015-12-01

    This paper presents a detailed description of LIRIC (LIdar-Radiometer Inversion Code) algorithm for simultaneous processing of coincident lidar and radiometric (sun photometric) observations for the retrieval of the aerosol concentration vertical profiles. As the lidar/radiometric input data we use measurements from European Aerosol Research Lidar Network (EARLINET) lidars and collocated sun-photometers of Aerosol Robotic Network (AERONET). The LIRIC data processing provides sequential inversion of the combined lidar and radiometric data by the estimations of column-integrated aerosol parameters from radiometric measurements followed by the retrieval of height-dependent concentrations of fine and coarse aerosols from lidar signals using integrated column characteristics of aerosol layer as a priori constraints. The use of polarized lidar observations allows us to discriminate between spherical and non-spherical particles of the coarse aerosol mode. The LIRIC software package was implemented and tested at a number of EARLINET stations. Intercomparison of the LIRIC-based aerosol retrievals was performed for the observations by seven EARLNET lidars in Leipzig, Germany on 25 May 2009. We found close agreement between the aerosol parameters derived from different lidars that supports high robustness of the LIRIC algorithm. The sensitivity of the retrieval results to the possible reduction of the available observation data is also discussed.

  14. Lidar-Radiometer Inversion Code (LIRIC) for the retrieval of vertical aerosol properties from combined lidar/radiometer data: development and distribution in EARLINET

    NASA Astrophysics Data System (ADS)

    Chaikovsky, Anatoli; Dubovik, Oleg; Holben, Brent; Bril, Andrey; Goloub, Philippe; Tanré, Didier; Pappalardo, Gelsomina; Wandinger, Ulla; Chaikovskaya, Ludmila; Denisov, Sergey; Grudo, Jan; Lopatin, Anton; Karol, Yana; Lapyonok, Tatsiana; Amiridis, Vassilis; Ansmann, Albert; Apituley, Arnoud; Allados-Arboledas, Lucas; Binietoglou, Ioannis; Boselli, Antonella; D'Amico, Giuseppe; Freudenthaler, Volker; Giles, David; José Granados-Muñoz, María; Kokkalis, Panayotis; Nicolae, Doina; Oshchepkov, Sergey; Papayannis, Alex; Perrone, Maria Rita; Pietruczuk, Alexander; Rocadenbosch, Francesc; Sicard, Michaël; Slutsker, Ilya; Talianu, Camelia; De Tomasi, Ferdinando; Tsekeri, Alexandra; Wagner, Janet; Wang, Xuan

    2016-03-01

    This paper presents a detailed description of LIRIC (LIdar-Radiometer Inversion Code) algorithm for simultaneous processing of coincident lidar and radiometric (sun photometric) observations for the retrieval of the aerosol concentration vertical profiles. As the lidar/radiometric input data we use measurements from European Aerosol Research Lidar Network (EARLINET) lidars and collocated sun-photometers of Aerosol Robotic Network (AERONET). The LIRIC data processing provides sequential inversion of the combined lidar and radiometric data. The algorithm starts with the estimations of column-integrated aerosol parameters from radiometric measurements followed by the retrieval of height dependent concentrations of fine and coarse aerosols from lidar signals using integrated column characteristics of aerosol layer as a priori constraints. The use of polarized lidar observations allows us to discriminate between spherical and non-spherical particles of the coarse aerosol mode.The LIRIC software package was implemented and tested at a number of EARLINET stations. Intercomparison of the LIRIC-based aerosol retrievals was performed for the observations by seven EARLINET lidars in Leipzig, Germany on 25 May 2009. We found close agreement between the aerosol parameters derived from different lidars that supports high robustness of the LIRIC algorithm. The sensitivity of the retrieval results to the possible reduction of the available observation data is also discussed.

  15. Long-term impacts of aerosols on the vertical development of clouds and precipitation

    SciTech Connect

    Li, Zhanqing; Niu, F.; Fan, Jiwen; Liu, Yangang; Rosenfeld, Daniel; Ding, Yanni

    2011-12-01

    Aerosol has complex effects on clouds and precipitation that may augment or offset each other contingent upon a variety of variables. As a result, its long-term impact on climate is largely unknown. Using 10 years of the US Atmospheric Radiation Measurement (ARM) measurements, strong aerosol effects of climatologically significance are detected. With increasing total aerosol number concentration (condensation nucleus, CN) measured near the ground, both cloud top height and precipitation change systematically for mix-phase clouds of warm-base (cloud base <1km) and cold-top (above the freezing level), but not for pure liquid and ice clouds. Cloud thickness can increase systematically with the CN concentration by up to a factor of 2. The response of precipitation to CN depends on cloud liquid water path (LWP). As CN increases, rain occurs more frequently for high LWP but less frequently for low LWP. Such strong signals of aerosol long-term impact on cloud and precipitation have not been reported and have significant implications for climate change studies, especially concerning regional and global climate change induced by pollution.

  16. Structural and Electrical Investigation of C60-Graphene Vertical Heterostructures.

    PubMed

    Kim, Kwanpyo; Lee, Tae Hoon; Santos, Elton J G; Jo, Pil Sung; Salleo, Alberto; Nishi, Yoshio; Bao, Zhenan

    2015-06-23

    Graphene, with its unique electronic and structural qualities, has become an important playground for studying adsorption and assembly of various materials including organic molecules. Moreover, organic/graphene vertical structures assembled by van der Waals interaction have potential for multifunctional device applications. Here, we investigate structural and electrical properties of vertical heterostructures composed of C60 thin film on graphene. The assembled film structure of C60 on graphene is investigated using transmission electron microscopy, which reveals a uniform morphology of C60 film on graphene with a grain size as large as 500 nm. The strong epitaxial relations between C60 crystal and graphene lattice directions are found, and van der Waals ab initio calculations support the observed phenomena. Moreover, using C60-graphene heterostructures, we fabricate vertical graphene transistors incorporating n-type organic semiconducting materials with an on/off ratio above 3 × 10(3). Our work demonstrates that graphene can serve as an excellent substrate for assembly of molecules, and attained organic/graphene heterostructures have great potential for electronics applications.

  17. Continental pollution in the Western Mediterranean Basin: vertical profiles of aerosol and trace gases measured over the sea during TRAQA 2012 and SAFMED 2013

    NASA Astrophysics Data System (ADS)

    Di Biagio, C.; Doppler, L.; Gaimoz, C.; Grand, N.; Ancellet, G.; Raut, J.-C.; Beekmann, M.; Borbon, A.; Sartelet, K.; Attié, J.-L.; Ravetta, F.; Formenti, P.

    2015-03-01

    In this study we present airborne observations of aerosol and trace gases obtained over the sea in the Western Mediterranean Basin during the TRAQA (TRansport and Air QuAlity) and SAFMED (Secondary Aerosol Formation in the MEDiterranean) campaigns in summers 2012 and 2013. A total of 23 vertical profiles were measured up to 5000 m a.s.l. over an extended area (40-45° N latitude and 2° W-12° E longitude) including the Gulf of Genoa, Southern France, the Gulf of Lion, and the Spanish coast. TRAQA and SAFMED successfully measured a wide range of meteorological conditions which favoured the pollution export from different sources located around the basin. Also, several events of dust outflows were measured during the campaigns. Observations from the present study indicate that continental pollution largely affects the Western Mediterranean both close to coastal regions and in the open sea as far as ~250 km from the coastline. Aerosol layers not specifically linked with Saharan dust outflows are distributed ubiquitously which indicates quite elevated levels of background pollution throughout the Western Basin. The measured aerosol scattering coefficient varies between ~20 and 120 M m-1, while carbon monoxide (CO) and ozone (O3) mixing ratios are in the range of 60-170 and 30-85 ppbv, respectively. Pollution reaches 3000-4000 m in altitude and presents a very complex and highly stratified structure characterized by fresh and aged layers both in the boundary layer and in the free troposphere. Within pollution plumes the measured particle concentration in the Aitken (0.004-0.1 μm) and accumulation (0.1-1.0 μm) modes is between ˜ 100 and 5000-6000 s cm-3 (standard cm-3), which is comparable to the aerosol concentration measured in continental urban areas. Additionally, our measurements indicate the presence of highly concentrated Aitken layers (10 000-15 000 s cm-3) observed both close to the surface and in the free troposphere, possibly linked to the influence of new

  18. Surface observations of aerosols and vertical ozone profiling: Influence from the Indo Gangetic Plain, biomass burning and LRT

    NASA Astrophysics Data System (ADS)

    Naja, M. K.; Kotamarthi, V. R.; Singh, N.; Phani, D. V.; Dumka, U. C.; Kumar, R.; Ojha, N.; Bhardhwaj, P.; Lal, S.

    2013-12-01

    South Asia is the home to one of the most populated and polluted region (The Indo-Gangetic Plain, IGP) of the world and variety of anthropogenic and biogenic emission sources are exiting in the same region. Despite of the poor understanding of the physical, chemical, and dynamical processes in the lower atmosphere over this region, there are very limited ground based observations in South Asia. In view of this, an observational facility was setup at ARIES, Nainital (29.4N, 79.5E; 1950 m) in the central Himalayas and at two sites in the IGP region for the surface based trace gases and aerosols observations as well as balloon-borne ozone observations. Further, First Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF1), DOE, was setup at ARIES during a GVAX campaign (June 2011-March 2012) and extensive observations of vertical profiling was also carried out using balloons, doppler Lidar, microwave radiometer, wind profiler and ceilometers. Observations of trace gases and aerosols show a clear enhancement during pre-monsoon and a secondary peak during post-monsoon period. The average scattering Angstrom exponent suggests dominance of relatively larger size particles and single scattering albedo indicates more scattering or less absorbing aerosols in this region. Events of the long-range transport are seen, when concentrations of bigger particle are observed to be higher. Apart from LRT, events of downward transport of ozone rich but drier air-masses are also observed. Extensive in-situ observations of ozone, CO, BC, aerosol absorption, scattering and number-concentration, along with back-air trajectories and MODIS fire-counts have been used to demonstrate evidences of the influence of biomass burning over this region. Aerosol organic enrichment and subsequent evolution to predominantly accumulation mode have been observed. This enrichment and its simultaneous size-growth caused it to get brighter during the biomass burning season. A very clear enhancement (20

  19. Cloud vertical structures detected by lidar and its statistical results at HeRO site in Hefei, China

    NASA Astrophysics Data System (ADS)

    Sun, Lu; Liu, Dong; Wang, Zhien; Wang, Zhenzhu; Wu, Decheng; Bo, Guangyu; Wang, Yingjian

    2014-11-01

    Extensive studies have illustrated the importance of obtaining exact vertical structures of clouds and aerosols for satellite and relevant climate simulations. However, challenging exists, for example, in distinguishing clouds from aerosols at times. Accurate cloud vertical profiles are mainly determined by cloud bases and heights. Based on the ground-based lidar observations in Hefei Radiation Observatory (HeRO), the vertical structures of clouds and aerosols in Hefei area(31.89°N 117.17°E) during May 2012-May 2014 have been investigated. The results show that the cloud fraction in the autumn and winter is less than that in the summer and spring, and is largest in the spring followed by the summer. The cloud fractions in the autumn and winter are comparable. The low cloud accounts for the most portion of the total. Compared with the cloud of the other heights, the high cloud is the least in the winter. Nearly 50% of the total vertical profiles can be detected by lidar as clouds and the proportion of the cloud of different heights seems to be stable annually. The fraction of low cloud is nearly 45%, medium cloud is nearly 35%, and high cloud is nearly 20%. In comparison with the results derived from CALIPSO, it is found that high cloud is usually missed for the ground-based lidar, while low cloud is usually omitted for the satellite observations. A combination of ground-based and space-borne lidar could lead to more reliable results. Further analysis will be performed in future studies.

  20. Impact of black carbon aerosol over Italian basin valleys: high-resolution measurements along vertical profiles, radiative forcing and heating rate

    NASA Astrophysics Data System (ADS)

    Ferrero, L.; Castelli, M.; Ferrini, B. S.; Moscatelli, M.; Perrone, M. G.; Sangiorgi, G.; D'Angelo, L.; Rovelli, G.; Moroni, B.; Scardazza, F.; Močnik, G.; Bolzacchini, E.; Petitta, M.; Cappelletti, D.

    2014-09-01

    A systematic study of black carbon (BC) vertical profiles measured at high-resolution over three Italian basin valleys (Terni Valley, Po Valley and Passiria Valley) is presented. BC vertical profiles are scarcely available in literature. The campaign lasted 45 days and resulted in 120 measured vertical profiles. Besides the BC mass concentration, measurements along the vertical profiles also included aerosol size distributions in the optical particle counter range, chemical analysis of filter samples and a full set of meteorological parameters. Using the collected experimental data, we performed calculations of aerosol optical properties along the vertical profiles. The results, validated with AERONET data, were used as inputs to a radiative transfer model (libRadtran). The latter allowed an estimation of vertical profiles of the aerosol direct radiative effect, the atmospheric absorption and the heating rate in the lower troposphere. The present measurements revealed some common behaviors over the studied basin valleys. Specifically, at the mixing height, marked concentration drops of both BC (range: from -48.4 ± 5.3 to -69.1 ± 5.5%) and aerosols (range: from -23.9 ± 4.3 to -46.5 ± 7.3%) were found. The measured percentage decrease of BC was higher than that of aerosols: therefore, the BC aerosol fraction decreased upwards. Correspondingly, both the absorption and scattering coefficients decreased strongly across the mixing layer (range: from -47.6 ± 2.5 to -71.3 ± 3.0% and from -23.5 ± 0.8 to -61.2 ± 3.1%, respectively) resulting in a single-scattering albedo increase along height (range: from +4.9 ± 2.2 to +7.4 ± 1.0%). This behavior influenced the vertical distribution of the aerosol direct radiative effect and of the heating rate. In this respect, the highest atmospheric absorption of radiation was predicted below the mixing height (~ 2-3 times larger than above it) resulting in a heating rate characterized by a vertical negative gradient (range

  1. Transport, vertical structure and radiative properties of dust events in southeast China determined from ground and space sensors

    NASA Astrophysics Data System (ADS)

    Liu, Jianjun; Zheng, Youfei; Li, Zhanqing; Flynn, Connor; Welton, E. J.; Cribb, Mareen

    2011-11-01

    Two dust events were detected over the Yangtze Delta region of China during March 14-17 and April 25-26 in 2009 where such dust events are uncommon. The transport behavior, spatio-temporal evolution, vertical structure, direct radiative effects, as well as induced heating rates, are investigated using a combination of ground-based and satellite-based measurements, a back-trajectory analysis, an aerosol model and a radiative transfer model. Back-trajectories, wind fields and aerosol model analyses show that the first dust originated in northern/northwestern China and the second generated in the Taklimakan desert in northwest China, and traveled across the Hexi corridor and Loess Plateau to the Yangtze Delta region (the so-called "dust corridor"). The mean lidar extinction-to-backscatter ratio (LR) during the two dust events was 38.7 ± 10.4 sr and 42.7 ± 15.2 sr, respectively. The mean aerosol depolarization ratio ( δa) for the first dust event was 0.16 ± 0.07, with a maximum value of 0.32. For the second, the mean δa was around 0.19 ± 0.06, with a maximum value of 0.29. Aerosol extinction coefficient and δa profiles for the two events were similar: two aerosol layers consisting of dust aerosols and a mixture of dust and anthropogenic pollution aerosols. The topmost aerosol layer is above 3.5 km. The maximum mean aerosol extinction coefficients were 0.5 km -1 and 0.54 km -1 at about 0.7 km and 1.1 km, respectively. Significant effects of cooling at the surface and heating in the atmosphere were found during these dust events. Diurnal mean shortwave radiative forcings (efficiencies) at the surface, the top-of-the-atmosphere and within the atmosphere were -36.8 (-80.0), -13.6 (-29.6) and 23.2 (50.4) W m -2, respectively, during the first dust event, and -48.2 (-70.9), -21.4 (-31.5) and 26.8 (39.4) W m -2, respectively, during the second dust event. Maximum heating rates occurred at 0.7 km during the first dust event and at 1.1 km during the second dust event

  2. Export industry structure upgrading and China's vertical specialization

    NASA Astrophysics Data System (ADS)

    Meng, Yinghua

    2011-10-01

    We computed the ratio of China's vertical specialization with revising method of Hummels et al. (2001). We found that China's export has the traits of processing trade, and Asian countries are the main exporter of intermediate goods to China; there is strong positive relationship between export ratio and ratio of China's vertical specialization, indicates that importing of intermediate goods play an important role in China's industry upgrading, China's comparative advantage of export still lies in low price of labor; even if China's production still locates in low value added stage in international supply chain, but China has began to advance its industry structure, and change the mode of production and trade that rely processing trade too much.

  3. A skeleton model for the MJO with refined vertical structure

    NASA Astrophysics Data System (ADS)

    Thual, Sulian; Majda, Andrew J.

    2016-05-01

    The Madden-Julian oscillation (MJO) is the dominant mode of variability in the tropical atmosphere on intraseasonal timescales and planetary spatial scales. The skeleton model is a minimal dynamical model that recovers robustly the most fundamental MJO features of (I) a slow eastward speed of roughly 5 {ms}^{-1}, (II) a peculiar dispersion relation with dω /dk ≈ 0, and (III) a horizontal quadrupole vortex structure. This model depicts the MJO as a neutrally-stable atmospheric wave that involves a simple multiscale interaction between planetary dry dynamics, planetary lower-tropospheric moisture and the planetary envelope of synoptic-scale activity. Here we propose and analyse an extended version of the skeleton model with additional variables accounting for the refined vertical structure of the MJO in nature. The present model reproduces qualitatively the front-to-rear vertical structure of the MJO found in nature, with MJO events marked by a planetary envelope of convective activity transitioning from the congestus to the deep to the stratiform type, in addition to a front-to-rear structure of moisture, winds and temperature. Despite its increased complexity the present model retains several interesting features of the original skeleton model such as a conserved energy and similar linear solutions. We further analyze a model version with a simple stochastic parametrization for the unresolved details of synoptic-scale activity. The stochastic model solutions show intermittent initiation, propagation and shut down of MJO wave trains, as in previous studies, in addition to MJO events with a front-to-rear vertical structure of varying intensity and characteristics from one event to another.

  4. Vertical distribution of agriculture crop residue burning aerosol observed by space-borne lidar CALIOP - A case study over the Indo-Gangetic Basin (IGB)

    NASA Astrophysics Data System (ADS)

    Mishra, A. K.; Shibata, T.

    2011-12-01

    Agriculture crop residue burning is one of the important sources of trace gas emissions and aerosol loading over the Indo-Gangetic Basin (IGB). It is also one of the main causes for dense atmospheric brown clouds (ABCs) formation over South Asian region. Present study deals with spatial and vertical variability of aerosol optical and microphysical properties during the crop residue burning season (October and November) over the IGB. MODIS (MODerate resolution Imaging Spectroradiometer) fire location data and MODIS AOD data confirms the crop residue burning activities over irrigated cropland of the IGB during October and November, 2009. Large values (> 0.7) of MODIS AOD (aerosol optical depth) and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) backscatter (>0.006 km-1 sr-1 below 1.0 km altitude) are suggesting enhanced atmospheric pollution associated with agriculture crop residue burning. The increase in tropospheric columnar NO2 and surface CO concentration during October and November also emphasized the significant contribution of crop residue burning activities in enhanced anthropogenic pollution over the IGB. Vertical distribution of backscatter coefficients showed trapping of biomass (crop residues) burning aerosol within boundary layer. Spatial variation of aerosol backscatter and AOD showed large value above north-west part of IGB, major area of crop residue burning activities. The results of this study will be very useful in quantification of optical properties of atmospheric brown clouds and its effect on climate.

  5. Exploring the Effects of Cloud Vertical Structure on Cloud Microphysical Retrievals based on Polarized Reflectances

    NASA Astrophysics Data System (ADS)

    Miller, D. J.; Zhang, Z.; Platnick, S. E.; Ackerman, A. S.; Cornet, C.; Baum, B. A.

    2013-12-01

    A polarized cloud reflectance simulator was developed by coupling an LES cloud model with a polarized radiative transfer model to assess the capabilities of polarimetric cloud retrievals. With future remote sensing campaigns like NASA's Aerosols/Clouds/Ecosystems (ACE) planning to feature advanced polarimetric instruments it is important for the cloud remote sensing community to understand the retrievable information available and the related systematic/methodical limitations. The cloud retrieval simulator we have developed allows us to probe these important questions in a realistically relevant test bed. Our simulator utilizes a polarized adding-doubling radiative transfer model and an LES cloud field from a DHARMA simulation (Ackerman et al. 2004) with cloud properties based on the stratocumulus clouds observed during the DYCOMS-II field campaign. In this study we will focus on how the vertical structure of cloud microphysics can influence polarized cloud effective radius retrievals. Numerous previous studies have explored how retrievals based on total reflectance are affected by cloud vertical structure (Platnick 2000, Chang and Li 2002) but no such studies about the effects of vertical structure on polarized retrievals exist. Unlike the total cloud reflectance, which is predominantly multiply scattered light, the polarized reflectance is primarily the result of singly scattered photons. Thus the polarized reflectance is sensitive to only the uppermost region of the cloud (tau~<1) where photons can scatter once and still escape before being scattered again. This means that retrievals based on polarized reflectance have the potential to reveal behaviors specific to the cloud top. For example cloud top entrainment of dry air, a major influencer on the microphysical development of cloud droplets, can be potentially studied with polarimetric retrievals.

  6. Contrasting Vertical Structures of the Stable Boundary Layer

    NASA Astrophysics Data System (ADS)

    Mahrt, L.; Vickers, Dean

    2002-01-01

    Wyngaard (1973) introduced the concept of z-less stratification for cases where the stratification is sufficiently strong, that the turbulence no longer is in significant communication with the surface (see also Holtslag and Nieuwstadt, 1986). Then z is no longer a primary scaling variable, nor is the boundary-layer depth. The eddies are vertically constrained by strong stratification. However, the z-less concept implies more than small eddies, since vertically continuous turbulence can still organize according to z even if the eddies at any level are small compared to z. For example, with local similarity where the relevant Obukhov length must be recast in terms of local fluxes at level z instead of surface fluxes (Nieuwstadt, 1984), the overall vertical structure is still posed in terms of z/h even if the eddy size is small compared to z. In this sense, local similarity still satisfies the criteria for traditional boundary layers. On the other hand, continuous turbulence between the surface and level z might still qualify as primarily z-less turbulence if the principal source of turbulence is detached from the surface and the distance above the ground surface is only a secondary influence.

  7. Complex vertical layering and mixing of aerosols over the eastern Mediterranean: active and passive remote sensing at the Cyprus University of Technology

    NASA Astrophysics Data System (ADS)

    Mamouri, R.-E.; Nisantzi, A.; Hadjimitsis, D. G.; Ansmann, A.; Schwarz, A.; Basart, S.; Baldasano, J. M.

    2013-08-01

    Aerosols can have a complicated influence on climate conditions, directly as well as indirectly via cloud formation. The southeastern Mediterranean region can be characterized as a cross road of aerosols originating from European, Asian and African continents. Complex vertical aerosol distributions are frequently detected over Cyprus by means of active remote sensing. Observations of such complex aerosol layering and comparison of the measurements with aerosol products of regional and global atmospheric transport models are required to improve our understanding of life cycles of aerosol mixtures and their impact on climate as well as on satellite remote sensing products. In this study, a case of an intense desert dust outbreak from Syria and Saudi Arabia towards the eastern Mediterranean in September 2011 is presented. The observations used in this study were performed with a 532-nm polarization Lidar and a sun/sky AERONET photometer operated at 8 channels from 340 to 1640 nm wavelength. Both instruments belong to remote sensing station of the Cyprus Technical University at Limassol, Cyprus (34°N, 33°E). The lofted dust plume was doped with air masses that crossed sources of biomass burning smoke and anthropogenic pollution. In addition, the shallow marine boundary layer over the Mediterranean Sea and over Limassol became mixed with the anthropogenic haze by sea breeze circulations. The case study demonstrates the potential of combined lidar/photometer observations to deliver detailed vertically resolved information of the aerosol characteristics in terms of particle optical and microphysical properties, separately for the spherical particle fraction as well as for the non-spherical aerosol mode.

  8. Profiling structured beams using injected aerosols

    NASA Astrophysics Data System (ADS)

    Loh, N. D.; Starodub, Dmitri; Lomb, Lukas; Hampton, Christina Y.; Martin, Andrew V.; Sierra, Raymond G.; Barty, Anton; Aquila, Andrew; Schulz, Joachim; Steinbrener, Jan; Shoeman, Robert L.; Kassemeyer, Stephan; Bostedt, Christoph; Bozek, John; Epp, Sascha W.; Erk, Benjamin; Hartmann, Robert; Rolles, Daniel; Rudenko, Artem; Rudek, Benedikt; Foucar, Lutz; Kimmel, Nils; Weidenspointner, Georg; Hauser, Günther; Holl, Peter; Pedersoli, Emanuele; Liang, MengNing; Hunter, Mark S.; Gumprecht, Lars; Coppola, Nicola; Wunderer, Cornelia; Graafsman, Heinz; Maia, Filipe R. N. C.; Ekeberg, Tomas; Hantke, Max; Fleckenstein, Holger; Hirsemann, Helmut; Nass, Karol; White, Thomas A.; Tobias, Herbert J.; Farquar, George R.; Benner, W. Henry; Hau-Riege, Stefan; Reich, Christian; Hartmann, Andreas; Soltau, Heike; Marchesini, Stefano; Bajt, Sasa; Barthelmess, Miriam; Strueder, Lothar; Ullrich, Joachim; Bucksbaum, Philip; Hodgson, Keith O.; Frank, Mathias; Schlichting, Ilme; Chapman, Henry N.; Bogan, Michael J.

    2012-10-01

    Profiling structured beams produced by X-ray free-electron lasers (FELs) is crucial to both maximizing signal intensity for weakly scattering targets and interpreting their scattering patterns. Earlier ablative imprint studies describe how to infer the X-ray beam profile from the damage that an attenuated beam inflicts on a substrate. However, the beams in-situ profile is not directly accessible with imprint studies because the damage profile could be different from the actual beam profile. On the other hand, although a Shack-Hartmann sensor is capable of in-situ profiling, its lenses may be quickly damaged at the intense focus of hard X-ray FEL beams. We describe a new approach that probes the in-situ morphology of the intense FEL focus. By studying the translations in diffraction patterns from an ensemble of randomly injected sub-micron latex spheres, we were able to determine the non-Gaussian nature of the intense FEL beam at the Linac Coherent Light Source (SLAC National Laboratory) near the FEL focus. We discuss an experimental application of such a beam-profiling technique, and the limitations we need to overcome before it can be widely applied.

  9. The Tropical Convective Spectrum. Part 1; Archetypal Vertical Structures

    NASA Technical Reports Server (NTRS)

    Boccippio, Dennis J.; Petersen, Walter A.; Cecil, Daniel J.

    2005-01-01

    A taxonomy of tropical convective and stratiform vertical structures is constructed through cluster analysis of 3 yr of Tropical Rainfall Measuring Mission (TRMM) "warm-season" (surface temperature greater than 10 C) precipitation radar (PR) vertical profiles, their surface rainfall, and associated radar-based classifiers (convective/ stratiform and brightband existence). Twenty-five archetypal profile types are identified, including nine convective types, eight stratiform types, two mixed types, and six anvil/fragment types (nonprecipitating anvils and sheared deep convective profiles). These profile types are then hierarchically clustered into 10 similar families, which can be further combined, providing an objective and physical reduction of the highly multivariate PR data space that retains vertical structure information. The taxonomy allows for description of any storm or local convective spectrum by the profile types or families. The analysis provides a quasi-independent corroboration of the TRMM 2A23 convective/ stratiform classification. The global frequency of occurrence and contribution to rainfall for the profile types are presented, demonstrating primary rainfall contribution by midlevel glaciated convection (27%) and similar depth decaying/stratiform stages (28%-31%). Profiles of these types exhibit similar 37- and 85-GHz passive microwave brightness temperatures but differ greatly in their frequency of occurrence and mean rain rates, underscoring the importance to passive microwave rain retrieval of convective/stratiform discrimination by other means, such as polarization or texture techniques, or incorporation of lightning observations. Close correspondence is found between deep convective profile frequency and annualized lightning production, and pixel-level lightning occurrence likelihood directly tracks the estimated mean ice water path within profile types.

  10. Vertical Structure of Magnetized Accretion Disks around Young Stars

    NASA Astrophysics Data System (ADS)

    Lizano, S.; Tapia, C.; Boehler, Y.; D'Alessio, P.

    2016-01-01

    We model the vertical structure of the magnetized accretion disks that are subject to viscous and resistive heating and irradiation by the central star. We apply our formalism to the radial structure of the magnetized accretion disks that are threaded by the poloidal magnetic field dragged during the process of star formation, which was developed by Shu and coworkers. We consider disks around low-mass protostars, T Tauri, and FU Orionis stars, as well as two levels of disk magnetization: {λ }{sys}=4 (strongly magnetized disks) and {λ }{sys}=12 (weakly magnetized disks). The rotation rates of strongly magnetized disks have large deviations from Keplerian rotation. In these models, resistive heating dominates the thermal structure for the FU Ori disk, and the T Tauri disk is very thin and cold because it is strongly compressed by magnetic pressure; it may be too thin compared with observations. Instead, in the weakly magnetized disks, rotation velocities are close to Keplerian, and resistive heating is always less than 7% of the viscous heating. In these models, the T Tauri disk has a larger aspect ratio, which is consistent with that inferred from observations. All the disks have spatially extended hot atmospheres where the irradiation flux is absorbed, although most of the mass (˜90%-95%) is in the disk midplane. With the advent of ALMA one expects direct measurements of magnetic fields and their morphology at disk scales. It will then be possible to determine the mass-to-flux ratio of magnetized accretion disks around young stars, an essential parameter for their structure and evolution. Our models contribute to the understanding of the vertical structure and emission of these disks.

  11. Evaluating the Use of MODIS AOD for Air Quality Determination by Comparison with the Vertical Distribution of Aerosol Light Scattering Coefficient Obtained with a Balloon-Borne Nephelometer

    NASA Astrophysics Data System (ADS)

    Sumlin, B.; Arnott, W. P.; Moosmuller, H.

    2012-12-01

    The MODIS instruments aboard the Aqua and Terra satellites provide aerosol optical depth information for the entire Earth on a daily basis. Ideally, satellite measurements should correlate with ground-based measurements in order to be useful for air quality applications. Reno, Nevada, USA is a high desert city situated in the Great Basin. Its unique geography and proximity to urban and biomass burning aerosol sources make it an ideal candidate for aerosol research. In August 2011, the Reno Aerosol Characterization Experiment measured atmospheric aerosols with a ground-based Cimel CE-318 sun-photometer and in situ photoacoustic instrumentation to quantify aerosol concentrations at the surface and in the column. However, the results of these measurements indicated the existence of a more complex system of aerosol mixing above the atmospheric boundary layer than previously thought. In order to validate these measurements, an autonomous suite of instrumentation has been developed. This device is carried aloft by a weather balloon and utilizes a reciprocal nephelometer to obtain a high-resolution profile of the vertical distribution of aerosol light scattering coefficient, as well as instrumentation to record atmospheric variables such as temperature, pressure, relative humidity, and dew point. Position, course, speed, and altitude are logged with an onboard GPS module and correlated with atmospheric and aerosol measurements. Presented is the design and development of this new instrument, its comparison with proven laboratory instruments, data gathered from flights during August-November 2012, and its comparison to ground-based measurements and satellite data from the MODIS instruments.

  12. Dependence of the drizzle growth process on the cloud top height and its relevance to the aerosol vertical profile

    NASA Astrophysics Data System (ADS)

    Kawamoto, K.; Suzuki, K.

    2013-12-01

    Transitional processes among cloud droplets, drizzle and raindrops are still uncertain and more efforts are required for the better understanding. In this situation, difference in the drizzle growth process was examined according to the cloud top height using the CloudSat and MODIS synergetic datasets. From the CloudSat products such as 2B-GEOPROF, 2B-TAU, ECMWF-AUX, only one-layered water clouds whose top temperatures were warmer than 273K were extracted over China (a circular area having a diameter of 1800km of the center at 35°N and 120°E) and over ocean (a circular area having a diameter of 1500km of the center at 35°N and 150°E). Then a threshold of 3km of the cloud top height was adopted to divide the extracted clouds into upper and lower cases. First, the probability distribution functions (PDF) of the cloud droplet number density (Nc) and the effective particle radius (Re) were calculated for these four cases (land/ocean/upper/lower). Nc was obtained assuming the adiabatic liquid water content from MODIS-derived cloud optical depth and Re. Oceanic clouds had fewer Nc than land clouds, and almost the same for upper and lower cases. Land clouds had more Nc for the lower case than for the higher case. On the other hand, oceanic clouds had larger Re than land clouds, and almost the same for upper and lower cases. Land clouds had smaller Re for the lower case than for the higher case. These results quite agreed with our existing knowledge on the vertical profile of the aerosol number concentration over ocean (pristine) and land (polluted). Although the number of aerosol particles is fewer and almost the same regardless of the height over the ocean, it is more near the surface and it rapidly decreases according to the height over the land. Next, examining PDF of the radar reflectivity (Ze), we found that although PDFs of Ze were almost the same for oceanic clouds regardless of the cloud top height, PDF of land lower clouds were less frequent at around from

  13. Vertical distribution of structural components in corn stover

    DOE PAGES

    Johnson, Jane M. F.; Karlen, Douglas L.; Gresham, Garold L.; Cantrell, Keri B.; Archer, David W.; Wienhold, Brian J.; Varvel, Gary E.; Laird, David A.; Baker, John; Ochsner, Tyson E.; et al

    2014-11-17

    In the United States, corn (Zea mays L.) stover has been targeted for second generation fuel production and other bio-products. Our objective was to characterize sugar and structural composition as a function of vertical distribution of corn stover (leaves and stalk) that was sampled at physiological maturity and about three weeks later from multiple USA locations. A small subset of samples was assessed for thermochemical composition. Concentrations of lignin, glucan, and xylan were about 10% greater at grain harvest than at physiological maturity, but harvestable biomass was about 25% less due to stalk breakage. Gross heating density above the earmore » averaged 16.3 ± 0.40 MJ kg⁻¹, but with an alkalinity measure of 0.83 g MJ⁻¹, slagging is likely to occur during gasification. Assuming a stover harvest height of 10 cm, the estimated ethanol yield would be >2500 L ha⁻¹, but it would be only 1000 L ha⁻¹ if stover harvest was restricted to the material from above the primary ear. Vertical composition of corn stover is relatively uniform; thus, decision on cutting height may be driven by agronomic, economic and environmental considerations.« less

  14. Vertical distribution of structural components in corn stover

    SciTech Connect

    Jane M. F. Johnson; Douglas L. Karlen; Garold L. Gresham; Keri B. Cantrell; David W. Archer; Brian J. Wienhold; Gary E. Varvel; David A. Laird; John Baker; Tyson E. Ochsner; Jeff M. Novak; Ardell D. Halvorson; Francisco Arriaga; David T. Lightle; Amber Hoover; Rachel Emerson; Nancy W. Barbour

    2014-11-01

    In the United States, corn (Zea mays L.) stover has been targeted for second generation fuel production and other bio-products. Our objective was to characterize sugar and structural composition as a function of vertical distribution of corn stover (leaves and stalk) that was sampled at physiological maturity and about three weeks later from multiple USA locations. A small subset of samples was assessed for thermochemical composition. Concentrations of lignin, glucan, and xylan were about 10% greater at grain harvest than at physiological maturity, but harvestable biomass was about 25% less due to stalk breakage. Gross heating density above the ear averaged 16.3 ± 0.40 MJ kg?¹, but with an alkalinity measure of 0.83 g MJ?¹, slagging is likely to occur during gasification. Assuming a stover harvest height of 10 cm, the estimated ethanol yield would be >2500 L ha?¹, but it would be only 1000 L ha?¹ if stover harvest was restricted to the material from above the primary ear. Vertical composition of corn stover is relatively uniform; thus, decision on cutting height may be driven by agronomic, economic and environmental considerations.

  15. Vertical distribution of structural components in corn stover

    SciTech Connect

    Johnson, Jane M. F.; Karlen, Douglas L.; Gresham, Garold L.; Cantrell, Keri B.; Archer, David W.; Wienhold, Brian J.; Varvel, Gary E.; Laird, David A.; Baker, John; Ochsner, Tyson E.; Novak, Jeff M.; Halvorson, Ardell D.; Arriaga, Francisco; Lightle, David T.; Hoover, Amber; Emerson, Rachel; Barbour, Nancy W.

    2014-11-17

    In the United States, corn (Zea mays L.) stover has been targeted for second generation fuel production and other bio-products. Our objective was to characterize sugar and structural composition as a function of vertical distribution of corn stover (leaves and stalk) that was sampled at physiological maturity and about three weeks later from multiple USA locations. A small subset of samples was assessed for thermochemical composition. Concentrations of lignin, glucan, and xylan were about 10% greater at grain harvest than at physiological maturity, but harvestable biomass was about 25% less due to stalk breakage. Gross heating density above the ear averaged 16.3 ± 0.40 MJ kg⁻¹, but with an alkalinity measure of 0.83 g MJ⁻¹, slagging is likely to occur during gasification. Assuming a stover harvest height of 10 cm, the estimated ethanol yield would be >2500 L ha⁻¹, but it would be only 1000 L ha⁻¹ if stover harvest was restricted to the material from above the primary ear. Vertical composition of corn stover is relatively uniform; thus, decision on cutting height may be driven by agronomic, economic and environmental considerations.

  16. Exploring the vertical age structure of the Galactic disc

    NASA Astrophysics Data System (ADS)

    Casagrande, Luca

    While in external or high-redshift galaxies we can only measure integrated stellar properties at best, the Milky Way offers us the unique opportunity to study its individual baryonic components, including stars. We use oscillations measured in red giant stars by the Kepler satellite to derive stellar ages and explore the vertical age structure across few kpc of the Milky Way disc. We find that old stars dominate at increasing Galactic heights, whereas closer to the plane a rich zoology of ages exists. The age distribution of stars shows a smooth distribution over the last 10 Gyr, which together with a flat age-metallicity relation is consistent with a quiescent evolution for the Milky Way disc since a redshift of about two.

  17. Exploring the vertical age structure of the Galactic disc

    NASA Astrophysics Data System (ADS)

    Casagrande, Luca; Silva Aguirre, Victor; Schlesinger, Katharine J.; Stello, Dennis; Huber, Daniel; Serenelli, Aldo; Schoenrich, Ralph; Asplund, Martin; Feltzing, Sofia

    2015-08-01

    While in external or high-redshift galaxies we can only measure integrated stellar properties at best, the Milky Way offers us the unique opportunity to study its individual baryonic components, including stars. We use oscillations measured in giant stars by the Kepler satellite to derive stellar ages and explore the vertical age structure across few kpc of the Milky Way disc. We find that old stars dominate at increasing Galactic heights, whereas closer to the plane a rich zoology of ages exists. The age distribution of stars shows a smooth decline over the last 10 Gyr, which together with a flat age-metallicity relation is consistent with a quiescent evolution for the Milky Way disc since a redshift of about two.

  18. The vertical structure and thickness of Saturn's rings

    NASA Technical Reports Server (NTRS)

    Cuzzi, J. N.; Durisen, R. H.; Burns, J. A.; Hamill, P.

    1979-01-01

    The steady state thickness and vertical structure of Saturn's rings are discussed with regard to whether a collapse to a monolayer due to particle collisions may be prevented by various mechanisms. The differences between thick rings and wavy monolayers are outlined and used to show that such coherent perturbations to the rings as satellite and solar gravitational effects would produce a wavy monolayer while such dispersive mechanisms as meteoroid impact, radiation pressure, Kepler shear and radial spreading, which would produce the random particle motions necessary to maintain a thick layer, are probably insignificant. Given a typical power law distribution of particle sizes, it is found that gravitational scattering of small particles by large ones would maintain a ring thickness of several times the radius of the largest particles. A steady state ring thickness of 20 to 50 meters, derived from energy considerations, would imply a maximum particle size of a few meters.

  19. Vertical variability of aerosol backscatter from an airborne-focused continuous-wave CO2 lidar at 9.1-microm wavelength.

    PubMed

    Jarzembski, M A; Srivastava, V; Rothermel, J

    1999-02-20

    Atmospheric aerosol backscatter measurements taken with a continuous-wave focused Doppler lidar at 9.1-microm wavelength were obtained over western North America and the Pacific Ocean from 13 to 26 September 1995 as part of a NASA airborne mission. Backscatter variability was measured for approximately 52 flight hours, covering an equivalent horizontal distance of approximately 30,000 km in the troposphere. Some quasi-vertical backscatter profiles were also obtained during various ascents and descents at altitudes that ranged from approximately 0.1 to 12 km. Similarities and differences for aerosol loading over land and ocean were observed. A midtropospheric aerosol backscatter background mode near 3 x 10(-11) to 1 x 10(-10) m(-1) sr(-1) was obtained, which is consistent with those of previous airborne and ground-based data sets. PMID:18305690

  20. Vertical Structure of Magnetized Accretion Disks Around Young Stars

    NASA Astrophysics Data System (ADS)

    Tapia, Carlos; Lizano, Susana

    2016-01-01

    We model the vertical structure of magnetized accretion disks subject to viscous and resistive heating, and irradiation by the central star. We apply our formalism to the radial structure of magnetized accretion disks threaded by a poloidal magnetic field dragged during the process of star formation developed by Shu and coworkers. We consider disks around low mass protostars, T Tauri, and FU Orionis stars. We consider two levels of disk magnetization, λsys = 4 (strongly magnetized disks), and λsys = 12 (weakly magnetized disks). The rotation rates of strongly magnetized disks have large deviations from Keplerian rotation. In these models, resistive heating dominates the thermal structure for the FU Ori disk. The T Tauri disk is very thin and cold because it is strongly compressed by magnetic pressure; it may be too thin compared with observations. Instead, in the weakly magnetized disks, rotation velocities are close to Keplerian, and resistive heating is always less than 7% of the viscous heating. In these models, the T Tauri disk has a larger aspect ratio, consistent with that inferred from observations. All the disks have spatially extended hot atmospheres where the irradiation flux is absorbed, although most of the mass (~ 90 - 95 %) is in the disk midplane.

  1. Quantifying Wintertime Aerosol Nitrate Formation Pathways and Their Vertical Profiles in the Great Lakes Region of North America by CMAQ Process Analysis and Hourly Observations

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Spak, S.; Carmichael, G. R.; Riemer, N. S.; Baek, J.; Fontaine, A.; Janssen, M.; Kenski, D. M.

    2012-12-01

    In order to better understand wintertime episodes of elevated fine particle (PM2.5) in the Great Lakes region, a modeling analysis using the CMAQ air quality model was conducted for January-March 2009, a period where special surface based observations were conducted at a pair of urban and rural sites in Wisconsin. The episodes are found to be regional and are characterized by low wind speeds, near-freezing temperatures, and elevated levels of ammonium nitrate. Integrated process rate (IPR) analysis and integrated reaction rate analysis (IRR) in 12 km regional simulations with the Community Multiscale Air Quality model (CMAQ) are employed to quantify contributions to nitrate formation from all simulated processes, most importantly local chemical production and transport. Substantial vertical profiles are found for nitric acid, nitrate, and N2O5. The maximum concentrations of aerosol nitrate occur at the surface and decrease with altitude. Nitric acid is produced most efficiently 50-200m above the surface at night. Surface concentrations of aerosol nitrate are maintained by downward transport via vertical diffusion. Aerosol nitrate is predominantly removed by dry deposition. The aerosol production rate is significantly higher during episodes, and both daytime and nighttime (N2O5) chemical pathways are important contributors to elevated concentrations. Near the surface at Milwaukee, the daytime formation pathway for nitric acid is larger than the nighttime pathways, while in rural areas, the relative magnitudes are reversed. Across the region, the importance of the nighttime pathway increases with altitude. A spatial analysis highlights regional variability at the surface layer and ~90m above surface for the period February 4 thru February 10, which includes two PM2.5 episodes. The net aerosol chemistry process rates and concentrations show the evolution of regional PM build-up of aerosol nitrate and nitric acid.

  2. Vertical Distribution and Columnar Optical Properties of Springtime Biomass-Burning Aerosols over Northern Indochina during the 7-SEAS/BASELInE field campaign

    NASA Astrophysics Data System (ADS)

    Lin, N. H.; Wang, S. H.; Welton, E. J.; Holben, B. N.; Tsay, S. C.; Giles, D. M.; Stewart, S. A.; Janjai, S.; Anh, N. X.; Hsiao, T. C.; Chen, W. N.; Lin, T. H.; Buntoung, S.; Chantara, S.; Wiriya, W.

    2015-12-01

    In this study, the aerosol optical properties and vertical distributions in major biomass-burning emission area of northern Indochina were investigated using ground-based remote sensing (i.e., four Sun-sky radiometers and one lidar) during the Seven South East Asian Studies/Biomass-burning Aerosols & Stratocumulus Environment: Lifecycles & Interactions Experiment conducted during spring 2014. Despite the high spatial variability of the aerosol optical depth (AOD; which at 500 nm ranged from 0.75 to 1.37 depending on the site), the temporal variation of the daily AOD demonstrated a consistent pattern among the observed sites, suggesting the presence of widespread smoke haze over the region. Smoke particles were characterized as small (Ångström exponent at 440-870 nm of 1.72 and fine mode fraction of 0.96), strongly absorbing (single-scattering albedo at 440 nm of 0.88), mixture of black and brown carbon particles (absorption Ångström exponent at 440-870 nm of 1.5) suspended within the planetary boundary layer (PBL). Smoke plumes driven by the PBL dynamics in the mountainous region reached as high as 5 km above sea level; these plumes subsequently spread out by westerly winds over northern Vietnam, southern China, and the neighboring South China Sea. Moreover, the analysis of diurnal variability of aerosol loading and optical properties as well as vertical profile in relation to PBL development, fire intensity, and aerosol mixing showed that various sites exhibited different variability based on meteorological conditions, fuel type, site elevation, and proximity to biomass-burning sources. These local factors influence the aerosol characteristics in the region and distinguish northern Indochina smoke from other biomass-burning regions in the world.

  3. North-south cross sections of the vertical aerosol distribution over the Atlantic Ocean from multiwavelength Raman/polarization lidar during Polarstern cruises

    PubMed Central

    Kanitz, T; Ansmann, A; Engelmann, R; Althausen, D

    2013-01-01

    Shipborne aerosol lidar observations were performed aboard the research vessel Polarstern in 2009 and 2010 during three north-south cruises from about 50°N to 50°S. The aerosol data set provides an excellent opportunity to characterize and contrast the vertical aerosol distribution over the Atlantic Ocean in the polluted northern and relatively clean southern hemisphere. Three case studies, an observed pure Saharan dust plume, a Patagonian dust plume east of South America, and a case of a mixed dust/smoke plume west of Central Africa are exemplarily shown and discussed by means of their optical properties. The meridional transatlantic cruises were used to determine the latitudinal cross section of the aerosol optical thickness (AOT). Profiles of particle backscatter and extinction coefficients are presented as mean profiles for latitudinal belts to contrast northern- and southern-hemispheric aerosol loads and optical effects. Results of lidar observations at Punta Arenas (53°S), Chile, and Stellenbosch (34°S), South Africa, are shown and confirm the lower frequency of occurrence of free-tropospheric aerosol in the southern hemisphere than in the northern hemisphere. The maximum latitudinal mean AOT of 0.27 was found in the northern tropics (0– 15°N) in the Saharan outflow region. Marine AOT is typically 0.05 ± 0.03. Particle optical properties are presented separately for the marine boundary layer and the free troposphere. Concerning the contrast between the anthropogenically influenced midlatitudinal aerosol conditions in the 30– 60°N belt and the respective belt in the southern hemisphere over the remote Atlantic, it is found that the AOT and extinction coefficients for the vertical column from 0–5km (total aerosol column) and 1–5km height (lofted aerosol above the marine boundary layer) are a factor of 1.6 and 2 higher at northern midlatitudes than at respective southern midlatitudes, and a factor of 2.5 higher than at the clean marine southern

  4. Retrieving Latent Heat Vertical Structure Using Precipitation and Cloud Profiles

    NASA Astrophysics Data System (ADS)

    Li, R.; Min, Q.; Wu, X.

    2011-12-01

    The latent heat (LH) released from tropical precipitation plays a critical role in driving regional and global atmosphere circulation. However, the vertical distribution of LH is one of most difficult parameters to be measured and has a large uncertainty in both residual diagnostic products and satellite retrievals. Most of current satellite LH products use limited observational information of precipitation and cloud profiles and highly depend on cloud resolving model (CRM) simulations. Our novel approach, distinguishing from existing schemes, is directly using observable precipitation and cloud profiles in combination with phase change partition parameterization of various kinds from the CRM simulations to produce the latent heating profiles. This hybrid latent heat algorithm separately deals with the condensation-evaporation heating (LHc_e), the deposition-sublimation heating (LHd_s) and the freezing-melting heating (LHf_m) for convective rain, stratiform rain, and shallow warm rain. Each component is based on physical processes, such as nucleation and auto conversion, by combining observable precipitation and cloud profiles. Although the proposed algorithm utilizes microphysical parameterizations from a specific CRM, the general LH vertical structure is primarily determined by the precipitation and cloud profiles observable from cloud and precipitation radars available at ground sites or from satellite platforms, and less sensitive to the specific CRM. The self consistency tests of this algorithm show good agreements with the CRM simulated LH at different spatial and temporal scales, even at simultaneous and pixel level. The applications of this algorithm are expected to provide new information for understanding the heating budget in the atmosphere and its impacts on the atmosphere circulations at various spatial and temporal scales.

  5. Waterspout - an Atmospheric Aerosol Dusty Plasma

    SciTech Connect

    Rantsev-Kartinov, V.A.

    2005-10-31

    An aerosol -- capillary electrostatic model of a waterspout is submitted. The waterspout is treated as a long-living filament of aerosol plasma, which is formed at electric breakdown of interval between a charged cloud and a vertically floating cylinder, which is individual block of ocean's skeletal structures of revealed recently by author.

  6. Exhaled Aerosol Pattern Discloses Lung Structural Abnormality: A Sensitivity Study Using Computational Modeling and Fractal Analysis

    PubMed Central

    Xi, Jinxiang; Si, Xiuhua A.; Kim, JongWon; Mckee, Edward; Lin, En-Bing

    2014-01-01

    Background Exhaled aerosol patterns, also called aerosol fingerprints, provide clues to the health of the lung and can be used to detect disease-modified airway structures. The key is how to decode the exhaled aerosol fingerprints and retrieve the lung structural information for a non-invasive identification of respiratory diseases. Objective and Methods In this study, a CFD-fractal analysis method was developed to quantify exhaled aerosol fingerprints and applied it to one benign and three malign conditions: a tracheal carina tumor, a bronchial tumor, and asthma. Respirations of tracer aerosols of 1 µm at a flow rate of 30 L/min were simulated, with exhaled distributions recorded at the mouth. Large eddy simulations and a Lagrangian tracking approach were used to simulate respiratory airflows and aerosol dynamics. Aerosol morphometric measures such as concentration disparity, spatial distributions, and fractal analysis were applied to distinguish various exhaled aerosol patterns. Findings Utilizing physiology-based modeling, we demonstrated substantial differences in exhaled aerosol distributions among normal and pathological airways, which were suggestive of the disease location and extent. With fractal analysis, we also demonstrated that exhaled aerosol patterns exhibited fractal behavior in both the entire image and selected regions of interest. Each exhaled aerosol fingerprint exhibited distinct pattern parameters such as spatial probability, fractal dimension, lacunarity, and multifractal spectrum. Furthermore, a correlation of the diseased location and exhaled aerosol spatial distribution was established for asthma. Conclusion Aerosol-fingerprint-based breath tests disclose clues about the site and severity of lung diseases and appear to be sensitive enough to be a practical tool for diagnosis and prognosis of respiratory diseases with structural abnormalities. PMID:25105680

  7. Application of the CALIOP Layer Product to Evaluate the Vertical Distribution of Aerosols Estimated by Global Models: AeroCom Phase I Results

    NASA Technical Reports Server (NTRS)

    Koffi, Brigitte; Schulz, Michael; Breon, Francois-Marie; Griesfeller, Jan; Winker, David; Balkanski, Yves; Bauer, Susanne; Berntsen, Terje; Chin, Mian; Collins, William D.; Dentener, Frank; Diehl, Thomas; Easter, Richard; Ghan, Steven; Gimoux, Paul; Gong, Sunling; Horowitz, Larry W.; Iversen, Trond; Kirkevag, Alf; Koch, Dorothy; Krol, Maarten; Myhre, Gunnar; Stier, Philip; Takemura, Toshihiko

    2012-01-01

    The CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) layer product is used for a multimodel evaluation of the vertical distribution of aerosols. Annual and seasonal aerosol extinction profiles are analyzed over 13 sub-continental regions representative of industrial, dust, and biomass burning pollution, from CALIOP 2007-2009 observations and from AeroCom (Aerosol Comparisons between Observations and Models) 2000 simulations. An extinction mean height diagnostic (Z-alpha) is defined to quantitatively assess the models' performance. It is calculated over the 0-6 km and 0-10 km altitude ranges by weighting the altitude of each 100 m altitude layer by its aerosol extinction coefficient. The mean extinction profiles derived from CALIOP layer products provide consistent regional and seasonal specificities and a low inter-annual variability. While the outputs from most models are significantly correlated with the observed Z-alpha climatologies, some do better than others, and 2 of the 12 models perform particularly well in all seasons. Over industrial and maritime regions, most models show higher Z-alpha than observed by CALIOP, whereas over the African and Chinese dust source regions, Z-alpha is underestimated during Northern Hemisphere Spring and Summer. The positive model bias in Z-alpha is mainly due to an overestimate of the extinction above 6 km. Potential CALIOP and model limitations, and methodological factors that might contribute to the differences are discussed.

  8. Application of the CALIOP Layer Product to Evaluate the Vertical Distribution of Aerosols Estimated by Global Models: AeroCom Phase I Results

    SciTech Connect

    Koffi, Brigitte; Schultz, Michael; Breon, Francois-Marie; Griesfeller, Jan; Winker, D.; Balkanski, Y.; Bauer, Susanne E.; Berntsen, T.; Chin, Mian; Collins, William D.; Dentener, Frank; Diehl, Thomas; Easter, Richard C.; Ghan, Steven J.; Ginoux, P.; Gong, S.; Horowitz, L.; Iversen, T.; Kirkevag, A.; Koch, Dorothy; Krol, Maarten; Myhre, G.; Stier, P.; Takemura, T.

    2012-05-19

    The CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) layer product is used for a multimodel evaluation of the vertical distribution of aerosols. Annual and seasonal aerosol extinction profiles are analyzed over 13 sub-continental regions representative of industrial, dust, and biomass burning pollution, from CALIOP 2007-2009 observations and from AeroCom (Aerosol Comparisons between Observations and Models) 2000 simulations. An extinction mean height diagnostic (Z{sub a}) is defined to quantitatively assess the models performance. It is calculated over the 0-6 km and 0-10 km altitude ranges by weighting the altitude of each 100 m altitude layer by its aerosol extinction coefficient. The mean extinction profiles derived from CALIOP layer products provide consistent regional and seasonal specificities and a low inter-annual variability. While the outputs from most models are significantly correlated with the observed Z{sub a} climatologies, some do better than others, and 2 of the 12 models perform particularly well in all seasons. Over industrial and maritime regions, most models show higher Z{sub a} than observed by CALIOP, whereas over the African and Chinese dust source regions, Z{sub a} is underestimated during Northern Hemisphere Spring and Summer. The positive model bias in Z{sub a} is mainly due to an overestimate of the extinction above 6 km. Potential CALIOP and model limitations, and methodological factors that might contribute to the differences are discussed.

  9. Vertical Profiles of Light-Absorbing Aerosol: A Combination of In-situ and AERONET Observations during NASA DISCOVER-AQ

    NASA Astrophysics Data System (ADS)

    Ziemba, L. D.; Beyersdorf, A. J.; Chen, G.; Corr, C.; Crumeyrolle, S.; Giles, D. M.; Holben, B. N.; Hudgins, C.; Martin, R.; Moore, R.; Shook, M.; Thornhill, K. L., II; Winstead, E.; Anderson, B. E.

    2014-12-01

    Understanding the vertical profile of atmospheric aerosols plays a vital role in utilizing spaceborne, column-integrated satellite observations. The properties and distribution of light-absorbing aerosol are particularly uncertain despite significant air quality and climate ramifications. Advanced retrieval algorithms are able to derive complex aerosol properties (e.g., wavelength-dependent absorption coefficient and single scattering albedo) from remote-sensing measurements, but quantitative relationships to surface conditions remain a challenge. Highly systematic atmospheric profiling during four unique deployments for the NASA DISCOVER-AQ project (Baltimore, MD, 2011; San Joaquin Valley, CA, 2013; Houston, TX, 2013; Denver, CO, 2014) allow statistical assessment of spatial, temporal, and source-related variability for light-absorbing aerosol properties in these distinct regions. In-situ sampling in conjunction with a dense network of AERONET sensors also allows evaluation of the sensitivity, limitations, and advantages of remote-sensing data products over a wide range of conditions. In-situ aerosol and gas-phase observations were made during DISCOVER-AQ aboard the NASA P-3B aircraft. Aerosol absorption coefficients were measured by a Particle Soot Absorption Photometer (PSAP). Approximately 200 profiles for each of the four deployments were obtained, from the surface (25-300m altitude) to 5 km, and are used to calculate absorption aerosol optical depths (AAODs). These are quantitatively compared to AAOD derived from AERONET Level 1.5 retrievals to 1) explore discrepancies between measurements, 2) quantify the fraction of AAOD that exists directly at the surface and is often missed by airborne sampling, and 3) evaluate the potential for deriving ground-level black carbon (BC) concentrations for air quality prediction. Aerosol size distributions are used to assess absorption contributions from mineral dust, both at the surface and aloft. SP2 (Single Particle Soot

  10. On the vertical structure of damped steady circulation in the tropics

    NASA Technical Reports Server (NTRS)

    Geisler, J. E.; Stevens, D. E.

    1982-01-01

    This paper presents an analysis of the vertical structure of steady motion in a dissipative tropical atmosphere forced by steady isolated diabatic heating. Vertical modes appropriate to the problem are obtained, and the forcing is projected onto these modes. With the use of an analytic expression obtained by Gill (1980) for the horizontal structure, these modes are summed to obtain the amplitude and the vertical structure of the response in the region to the east of the heating.

  11. ON THE VERTICAL STRUCTURE OF THE PROTOLUNAR DISK

    SciTech Connect

    Ward, William R.

    2012-01-10

    The vertical structure of a post-impact, pre-lunar disk is examined. We adopt the equations introduced by Thompson and Stevenson for a silicate disk in two-phase equilibrium (vapor plus liquid) and derive an analytical solution to the system. This largely reproduces their low-gas mass fraction, x << 1, profiles of the disk but is also employed to examine higher x cases. The latter are generally gravitationally stable and are used to develop a stratified disk model consisting of a gravitationally unstable magma layer surrounded by a stable, primarily vapor atmosphere. Initially, the atmosphere contains the majority of the disk mass, while the surface density of the magma layer is determined by requiring its viscous energy dissipation supply the disk's radiation budget. The magma layer viscously spreads on a {approx}50 yr timescale during which vapor continuously condenses into droplets that settle to the layer, maintaining its surface density and dissipation rate. Material flowing outward, past the Roche boundary, can become incorporated into accreting moonlets, and this supply persists until the vapor reservoir is depleted in {approx}250 yr.

  12. Vertical structure of foggy haze over the Beijing-Tianjin-Hebei area in January 2013

    NASA Astrophysics Data System (ADS)

    Han, Feng; Xu, Jun; He, Youjiang; Dang, Hongyan; Yang, Xuezhen; Meng, Fan

    2016-08-01

    In January 2013, frequent episodes of intense air pollution occurred in the Beijing-Tianjin-Hebei area (BTH), China. Besides the occurrence of region-wide dry haze pollution, foggy haze conditions also developed across the region on numerous days, lasting into the afternoon. Synergistic analysis, using multisatellite datasets, air sounding and surface meteorological observations, indicated that there was a vertical overlap of fog and aerosol layers during the foggy haze episodes in the region. Fog appeared at a low level of the atmosphere. The altitude of the upper boundary of the fog differed across the region, but it was always below 1 km. The aerosol layer that closely contacted with the top of the underlying fog was rather dense, having a high concentration comparable to that during severe pollution on the ground. Above the dense aerosol layer, aerosol with a concentration equivalent to that of moderate pollution stretched up to an altitude of 2 km. Beyond that, a tenuous aerosol layer extended 5 km into the atmosphere. This overlapping of fog and haze layers frequently occurred across the region in January 2013. The occurrence of a foggy haze over BTH could worsen the regional air quality, and its appearance across this region would have notable effects on the radiation balance.

  13. Investigating the Internal Structure of Individual Aerosol Particles Using Atomic Force and Raman Microscopies

    NASA Astrophysics Data System (ADS)

    Freedman, M. A.; Baustian, K. J.; Wise, M. E.; Tolbert, M. A.

    2009-12-01

    We have used Atomic Force Microscopy (AFM) and Raman Microscopy to probe aerosol internal structures in order to understand the optical properties of aerosols composed of mixtures of organic and inorganic components. While AFM gives only topographical information about the particles, indirect chemical information can be obtained by using substrates with different surface properties. With Raman microscopy, chemical signatures of the components of the aerosol are obtained, but we have limited spatial resolution. We have explored the use of these two techniques to look at aerosol internal structure using a range of different model aerosols composed of mixtures of ammonium sulfate with organic compounds of various solubilities such as sucrose, succinic acid, and palmitic acid. At the extremes of solubility, AFM provides suitable information for interpreting aerosol microstructure. For example, AFM clearly shows the presence of core-shell structures for aerosol particles composed of palmitic acid and ammonium sulfate, while the results for aerosol particles composed of succinic acid and ammonium sulfate are more difficult to interpret. Information about size and shape can be obtained when hydrophilic particles are impacted on hydrophobic substrates and vise versa. With Raman microscopy, core-shell structures were readily identified for ammonium sulfate with palmitic acid or succinic acid coatings. For the case of succinic acid and ammonium sulfate mixtures, we are using microscopy results to aid in interpreting the refractive indices we retrieved from cavity ring-down studies.

  14. Mediterranean desert dust outbreaks and their vertical structure based on remote sensing data

    NASA Astrophysics Data System (ADS)

    Gkikas, A.; Basart, S.; Hatzianastassiou, N.; Marinou, E.; Amiridis, V.; Kazadzis, S.; Pey, J.; Querol, X.; Jorba, O.; Gassó, S.; Baldasano, J. M.

    2015-10-01

    The main aim of the present study is to describe the vertical structure of the intense Mediterranean dust outbreaks, based on the use of satellite and surface-based retrievals/measurements. Strong and extreme desert dust (DD) episodes are identified at 1° × 1° spatial resolution, over the period March 2000-February 2013, through the implementation of an updated objective and dynamic algorithm. According to the algorithm, strong DD episodes occurring at a specific place correspond to cases in which the daily aerosol optical depth at 550 nm (AOD550 nm) exceeds or equals the long-term mean AOD550 nm (Mean) plus two standard deviations (SD) value being smaller than Mean + 4 · SD. Extreme DD episodes correspond to cases in which the daily AOD550 nm value equals or exceeds Mean + 4 · SD. For the identification of DD episodes additional optical properties (Ångström exponent, fine fraction, effective radius and Aerosol Index) derived by the MODIS-Terra & Aqua (also AOD retrievals), OMI-Aura and EP-TOMS databases are used as inputs. According to the algorithm using MODIS-Terra data, over the period March 2000-February 2013, strong DD episodes occur more frequently (up to 9.9 episodes yr-1) over the western Mediterranean while the corresponding frequencies for the extreme ones are smaller (up to 3.3 episodes yr-1, central Mediterranean Sea). In contrast to their frequency, dust episodes are more intense (AODs up to 4.1), over the central and eastern Mediterranean Sea, off the northern African coasts. Slightly lower frequencies and higher intensities are found when the satellite algorithm operates based on MODIS-Aqua retrievals, for the period 2003-2012. The performance of the satellite algorithm is assessed against surface-based daily data from 109 sun-photometric (AERONET) and 22 PM10 stations. The agreement between AERONET and MODIS AOD is satisfactory (R = 0.505 - 0.75) improving considerably when MODIS level 3 retrievals with higher sub-grid spatial

  15. A new method for estimating aerosol mass flux in the urban surface layer using LAS technology

    NASA Astrophysics Data System (ADS)

    Yuan, Renmin; Luo, Tao; Sun, Jianning; Liu, Hao; Fu, Yunfei; Wang, Zhien

    2016-04-01

    Atmospheric aerosol greatly influences human health and the natural environment, as well as the weather and climate system. Therefore, atmospheric aerosol has attracted significant attention from society. Despite consistent research efforts, there are still uncertainties in understanding its effects due to poor knowledge about aerosol vertical transport caused by the limited measurement capabilities of aerosol mass vertical transport flux. In this paper, a new method for measuring atmospheric aerosol vertical transport flux is developed based on the similarity theory of surface layer, the theory of light propagation in a turbulent atmosphere, and the observations and studies of the atmospheric equivalent refractive index (AERI). The results show that aerosol mass flux can be linked to the real and imaginary parts of the atmospheric equivalent refractive index structure parameter (AERISP) and the ratio of aerosol mass concentration to the imaginary part of the AERI. The real and imaginary parts of the AERISP can be measured based on the light-propagation theory. The ratio of the aerosol mass concentration to the imaginary part of the AERI can be measured based on the measurements of aerosol mass concentration and visibility. The observational results show that aerosol vertical transport flux varies diurnally and is related to the aerosol spatial distribution. The maximum aerosol flux during the experimental period in Hefei City was 0.017 mg m-2 s-1, and the mean value was 0.004 mg m-2 s-1. The new method offers an effective way to study aerosol vertical transport in complex environments.

  16. Characterizing the vertical profile of aerosol particle extinction and linear depolarization over Southeast Asia and the Maritime Continent: The 2007-2009 view from CALIOP

    NASA Astrophysics Data System (ADS)

    Campbell, James R.; Reid, Jeffrey S.; Westphal, Douglas L.; Zhang, Jianglong; Tackett, Jason L.; Chew, Boon Ning; Welton, Ellsworth J.; Shimizu, Atsushi; Sugimoto, Nobuo; Aoki, Kazuma; Winker, David M.

    2013-03-01

    Vertical profiles of 0.532 μm aerosol particle extinction coefficient and linear volume depolarization ratio are described for Southeast Asia and the Maritime Continent. Quality-screened and cloud-cleared Version 3.01 Level 2 NASA Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) 5-km Aerosol Profile datasets are analyzed from 2007 to 2009. Numerical simulations from the U.S. Naval Aerosol Analysis and Predictive System (NAAPS), featuring two-dimensional variational assimilation of NASA Moderate Resolution Imaging Spectroradiometer and Multi-angle Imaging SpectroRadiometer quality-assured datasets, combined with regional ground-based lidar measurements, are considered for assessing CALIOP retrieval performance, identifying bias, and evaluating regional representativeness. CALIOP retrievals of aerosol particle extinction coefficient and aerosol optical depth (AOD) are high over land and low over open waters relative to NAAPS (0.412/0.312 over land for all data points inclusive, 0.310/0.235 when the per bin average is used and each is treated as single data points; 0.102/0.151 and 0.086/0.124, respectively, over ocean). Regional means, however, are very similar (0.180/0.193 for all data points and 0.155/0.159 when averaged per normalized bin), as the two factors offset one another. The land/ocean offset is investigated, and discrepancies attributed to interpretation of particle composition and a-priori assignment of the extinction-to-backscatter ratio (“lidar ratio”) necessary for retrieving the extinction coefficient from CALIOP signals. Over land, NAAPS indicates more dust present than CALIOP algorithms are identifying, indicating a likely assignment of a higher lidar ratio representative of more absorptive particles. NAAPS resolves more smoke over water than identified with CALIOP, indicating likely usage of a lidar ratio characteristic of less absorptive particles to be applied that biases low AOD there. Over open waters except within the Bay of

  17. Characterizing the Vertical Profile of Aerosol Particle Extinction and Linear Depolarization over Southeast Asia and the Maritime Continent: The 2007-2009 View from CALIOP

    NASA Technical Reports Server (NTRS)

    Campbell, James R.; Reid, Jeffrey S.; Westphal, Douglas L.; Zhang, Jianglong; Tackett, Jason L.; Chew, Boon Ning; Welton, Ellsworth J.; Shimizu, Atsushi; Sugimoto, Nobuo; Aoki, Kazuma; Winker, David M.

    2012-01-01

    Vertical profiles of 0.532 µm aerosol particle extinction coefficient and linear volume depolarization ratio are described for Southeast Asia and the Maritime Continent. Quality-screened and cloud-cleared Version 3.01 Level 2 NASA Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) 5-km Aerosol Profile datasets are analyzed from 2007 to 2009. Numerical simulations from the U.S. Naval Aerosol Analysis and Predictive System (NAAPS), featuring two-dimensional variational assimilation of NASA Moderate Resolution Imaging Spectroradiometer and Multi-angle Imaging Spectro- Radiometer quality-assured datasets, combined with regional ground-based lidar measurements, are considered for assessing CALIOP retrieval performance, identifying bias, and evaluating regional representativeness. CALIOP retrievals of aerosol particle extinction coefficient and aerosol optical depth (AOD) are high over land and low over open waters relative to NAAPS (0.412/0.312 over land for all data points inclusive, 0.310/0.235 when the per bin average is used and each is treated as single data points; 0.102/0.151 and 0.086/0.124, respectively, over ocean). Regional means, however, are very similar (0.180/0.193 for all data points and 0.155/0.159 when averaged per normalized bin), as the two factors offset one another. The land/ocean offset is investigated, and discrepancies attributed to interpretation of particle composition and a-priori assignment of the extinction-to-backscatter ratio ("lidar ratio") necessary for retrieving the extinction coefficient from CALIOP signals. Over land, NAAPS indicates more dust present than CALIOP algorithms are identifying, indicating a likely assignment of a higher lidar ratio representative of more absorptive particles. NAAPS resolvesmore smoke overwater than identified with CALIOP, indicating likely usage of a lidar ratio characteristic of less absorptive particles to be applied that biases low AOD there. Over open waters except within the Bay of Bengal

  18. Mediterranean intense desert dust outbreaks and their vertical structure based on remote sensing data

    NASA Astrophysics Data System (ADS)

    Gkikas, Antonis; Basart, Sara; Hatzianastassiou, Nikos; Marinou, Eleni; Amiridis, Vassilis; Kazadzis, Stelios; Pey, Jorge; Querol, Xavier; Jorba, Oriol; Gassó, Santiago; Baldasano, José Maria

    2016-07-01

    The main aim of the present study is to describe the vertical structure of the intense Mediterranean dust outbreaks, based on the use of satellite and surface-based retrievals/measurements. Strong and extreme desert dust (DD) episodes are identified at 1° × 1° spatial resolution, over the period March 2000-February 2013, through the implementation of an updated objective and dynamic algorithm. According to the algorithm, strong DD episodes occurring at a specific place correspond to cases in which the daily aerosol optical depth at 550 nm (AOD550 nm) exceeds or equals the long-term mean AOD550 nm (Mean) plus two standard deviations (SD), which is also smaller than Mean+4 × SD. Extreme DD episodes correspond to cases in which the daily AOD550 nm value equals or exceeds Mean+4 × SD. For the identification of DD episodes, additional optical properties (Ångström exponent, fine fraction, effective radius and aerosol index) derived by the MODIS-Terra & Aqua (also AOD retrievals), OMI-Aura and EP-TOMS databases are used as inputs. According to the algorithm using MODIS-Terra data, over the period March 2000-February 2013, strong DD episodes occur more frequently (up to 9.9 episodes year-1) over the western Mediterranean, while the corresponding frequencies for the extreme ones are smaller (up to 3.3 episodes year-1, central Mediterranean Sea). In contrast to their frequency, dust episodes are more intense (AODs up to 4.1), over the central and eastern Mediterranean Sea, off the northern African coasts. Slightly lower frequencies and higher intensities are found when the satellite algorithm operates based on MODIS-Aqua retrievals, for the period 2003-2012. The consistency of the algorithm is successfully tested through the application of an alternative methodology for the determination of DD episodes, which produced similar features of the episodes' frequency and intensity, with just slightly higher frequencies and lower intensities. The performance of the

  19. Measuring the vertical distributions of the upper tropospheric and stratospheric dust with a LOAC aerosol counter under meteorological balloons

    NASA Astrophysics Data System (ADS)

    Vignelles, Damien; Renard, Jean-Baptiste; Berthet, Gwenael; Dulac, François; Coute, Benoit; Jeannot, Matthieu; Jegou, Fabrice; Olafsson, Haraldur; Dagsson Waldhauserova, Pavla

    2014-05-01

    The aerosol issue is in a constant growing. At ground, the airborne particles in boundary layer represent a real risk for population and must be control. In the middle troposphere, aerosols play an important role in the microphysics and meteorology, the heterogeneous chemistry is not well understood. In the stratosphere, several teams of researchers have shown that solid aerosols might exist, the question of the dynamic of these solid aerosol in the stratosphere is open. The aim was to develop an instrument that it can make measurements from the ground to the middle stratosphere. This instrument must be able to be put under meteorological balloons, which represent the worst conditions for the development of such instruments in terms of weight, resistance under large variations of temperature and pressure, autonomy and cost if we consider that something throw under a meteorological balloon can be lost after the fly. In the consideration of these conditions, we have developed a new instrument able to make such kind of measurements. This instrument is call LOAC for Light Optical Aerosol Counter. LOAC provides the concentration and size distribution of aerosols on 19 channels from 0.2 μm to 50.0 μm every ten seconds, and determine the main nature of particles (carbonaceous aerosol, mineral, droplets of water or sulfuric acid) in relation with a large range of samples in laboratory. The physical technique is based on the observation of the scattered light by particles at two angles. LOAC is light enough (1 kilogram) to be placed under a meteorological balloon that is very easy to launch such balloons. The goal is to perform a large number of flights to gather information about the dust distribution in stratosphere and to understand the various mechanisms controlling their spatial and temporal variability. About 25 flights with have been performed in the stratosphere with the LOAC above the Mediterranean Sea, from south of Paris, from Aire-Sur-l'Adour (South-West of

  20. Ambient Observations of Aerosols, Novel Aerosol Structures, And Their Engineering Applications

    NASA Astrophysics Data System (ADS)

    Beres, Nicholas D.

    The role of atmospheric aerosols remains a crucial issue in understanding and mitigating climate change in our world today. These particles influence the Earth by altering the Earth's delicate radiation balance, human health, and visibility. In particular, black carbon particulate matter remains the key driver in positive radiative forcing (i.e., warming) due to aerosols. Produced from the incomplete combustion of hydrocarbons, these compounds can be found in many different forms around the globe. This thesis provides an overview of three research topics: (1) the ambient characterization of aerosols in the Northern Indian Ocean, measurement techniques used, and how these aerosols influence local, regional, and global climate; (2) the exploration of novel soot superaggregate particles collected in the Northern Indian Ocean and around the globe and how the properties of these particles relate to human health and climate forcing; and (3) how aerogelated soot can be produced in a novel, one-step method utilizing an inverted flame reactor and how this material could be used in industrial settings.

  1. Cloud Vertical and Horizontal Structure from ICESat/GLAS and MODIS

    NASA Technical Reports Server (NTRS)

    Marshak, Alexander; Chiu, Christine; Davis, Anthony; Wiscombe, Warren

    2007-01-01

    To accurately model radiative fluxes at the surface and within the atmosphere, we need to know both vertical and horizontal structures of cloudiness. While MODIS provides accurate information on cloud horizontal structure, it has limited ability to estimate cloud vertical structure. ICESat/GLAS on the other hand, provides the vertical distribution and internal structure of clouds as deep as the laser beam can penetrate and return a signal. Having different orbits, MODIS and GLAS provide few collocated measurements; hence a statistical approach is needed to learn about 3D cloud structures from the two instruments. In the presentation, we show the results of the statistical analysis of vertical and horizontal structure of cloudiness using GLAS and MODIS cloud top(s) data acquired in October-November 2003. We revisit the (H1, C1) plot, previously used for analyzing cloud liquid water data, and illustrate cloud structure for single and multiple-layer clouds.

  2. The chemical evolution & physical properties of organic aerosol: A molecular structure based approach

    NASA Astrophysics Data System (ADS)

    Wei, Yiyi; Cao, Tingting; Thompson, Jonathan E.

    2012-12-01

    Global climate, atmospheric chemistry, and air quality are affected by tropospheric particulate matter. Recent measurements suggest organic compounds present in this haze comprise roughly half of total aerosol fine mass concentration globally. Unlike the well-constrained processes which result in formation of nitrate or sulfate aerosol, the oxidation of volatile organics in the atmosphere can lead to thousands of stable compounds in the aerosol phase. Development of a tractable framework to consider the chemical and physical evolution of the organic aerosol is crucial for modeling its effect on global climate. Here we show coupling a 3-dimensional coordinate system defined by the molecular descriptors of molecular weight, heteroatom mass, and double bond equivalents (D.B.E.) with high-resolution molecular mass spectrometry is a powerful approach for describing key properties of the organic aerosol. The scheme is conceptually simple, yet maintains sufficient complexity to be compatible with quantitative structure-property relationships (QSPRs) used to predict chemical and physical properties that govern aerosol behavior. From available data, both ambient organic aerosol and laboratory generated organic aerosol frequently occupy the region characterized by <10 D.B.E. <600 M.W. and <200 heteroatom mass. A QSPR analysis conducted illustrates spatial trends within the 3D space for volatility and Henry's law constants for 31,000 organic compounds considered.

  3. Ice crystallization in ultrafine water-salt aerosols: nucleation, ice-solution equilibrium, and internal structure.

    PubMed

    Hudait, Arpa; Molinero, Valeria

    2014-06-01

    Atmospheric aerosols have a strong influence on Earth's climate. Elucidating the physical state and internal structure of atmospheric aqueous aerosols is essential to predict their gas and water uptake, and the locus and rate of atmospherically important heterogeneous reactions. Ultrafine aerosols with sizes between 3 and 15 nm have been detected in large numbers in the troposphere and tropopause. Nanoscopic aerosols arising from bubble bursting of natural and artificial seawater have been identified in laboratory and field experiments. The internal structure and phase state of these aerosols, however, cannot yet be determined in experiments. Here we use molecular simulations to investigate the phase behavior and internal structure of liquid, vitrified, and crystallized water-salt ultrafine aerosols with radii from 2.5 to 9.5 nm and with up to 10% moles of ions. We find that both ice crystallization and vitrification of the nanodroplets lead to demixing of pure water from the solutions. Vitrification of aqueous nanodroplets yields nanodomains of pure low-density amorphous ice in coexistence with vitrified solute rich aqueous glass. The melting temperature of ice in the aerosols decreases monotonically with an increase of solute fraction and decrease of radius. The simulations reveal that nucleation of ice occurs homogeneously at the subsurface of the water-salt nanoparticles. Subsequent ice growth yields phase-segregated, internally mixed, aerosols with two phases in equilibrium: a concentrated water-salt amorphous mixture and a spherical cap-like ice nanophase. The surface of the crystallized aerosols is heterogeneous, with ice and solution exposed to the vapor. Free energy calculations indicate that as the concentration of salt in the particles, the advance of the crystallization, or the size of the particles increase, the stability of the spherical cap structure increases with respect to the alternative structure in which a core of ice is fully surrounded by

  4. Ice crystallization in ultrafine water-salt aerosols: nucleation, ice-solution equilibrium, and internal structure.

    PubMed

    Hudait, Arpa; Molinero, Valeria

    2014-06-01

    Atmospheric aerosols have a strong influence on Earth's climate. Elucidating the physical state and internal structure of atmospheric aqueous aerosols is essential to predict their gas and water uptake, and the locus and rate of atmospherically important heterogeneous reactions. Ultrafine aerosols with sizes between 3 and 15 nm have been detected in large numbers in the troposphere and tropopause. Nanoscopic aerosols arising from bubble bursting of natural and artificial seawater have been identified in laboratory and field experiments. The internal structure and phase state of these aerosols, however, cannot yet be determined in experiments. Here we use molecular simulations to investigate the phase behavior and internal structure of liquid, vitrified, and crystallized water-salt ultrafine aerosols with radii from 2.5 to 9.5 nm and with up to 10% moles of ions. We find that both ice crystallization and vitrification of the nanodroplets lead to demixing of pure water from the solutions. Vitrification of aqueous nanodroplets yields nanodomains of pure low-density amorphous ice in coexistence with vitrified solute rich aqueous glass. The melting temperature of ice in the aerosols decreases monotonically with an increase of solute fraction and decrease of radius. The simulations reveal that nucleation of ice occurs homogeneously at the subsurface of the water-salt nanoparticles. Subsequent ice growth yields phase-segregated, internally mixed, aerosols with two phases in equilibrium: a concentrated water-salt amorphous mixture and a spherical cap-like ice nanophase. The surface of the crystallized aerosols is heterogeneous, with ice and solution exposed to the vapor. Free energy calculations indicate that as the concentration of salt in the particles, the advance of the crystallization, or the size of the particles increase, the stability of the spherical cap structure increases with respect to the alternative structure in which a core of ice is fully surrounded by

  5. Electrospray neutralization process and apparatus for generation of nano-aerosol and nano-structured materials

    DOEpatents

    Bailey, Charles L.; Morozov, Victor; Vsevolodov, Nikolai N.

    2010-08-17

    The claimed invention describes methods and apparatuses for manufacturing nano-aerosols and nano-structured materials based on the neutralization of charged electrosprayed products with oppositely charged electrosprayed products. Electrosprayed products include molecular ions, nano-clusters and nano-fibers. Nano-aerosols can be generated when neutralization occurs in the gas phase. Neutralization of electrospan nano-fibers with molecular ions and charged nano-clusters may result in the formation of fibrous aerosols or free nano-mats. Nano-mats can also be produced on a suitable substrate, forming efficient nano-filters.

  6. Vertical Structure of Ozone Over the Gulf of Maine Observed During NEAQS 2002: Implications for Air Quality in New England

    NASA Astrophysics Data System (ADS)

    Senff, C. J.; Alvarez, R. J.; Eberhard, W. L.; McCarty, B. J.; White, A. B.; Angevine, W. M.; Williams, E. J.; Goldan, P. D.

    2003-12-01

    The main objective of the 2002 New England Air Quality Study (NEAQS) was to characterize and understand the chemical and meteorological processes that contribute to high-pollution events in northern New England, particularly in coastal areas of New Hampshire and Maine. The primary measurement platform of this study was the NOAA research vessel Ronald H. Brown, which spent about three weeks in July and August of 2002 in the Gulf of Maine and was equipped with an extensive set of chemical and meteorological sensors. Researchers at the NOAA Environmental Technology Laboratory deployed a vertically pointed lidar on the Ronald H. Brown to characterize the vertical structure of ozone and aerosols over the Gulf of Maine and to assess the representativeness of in situ chemical and aerosol measurements aboard the ship for the entire marine boundary layer. The lidar measurements showed that most of the time, particularly during onshore flow, ozone values at around 300 m MSL were significantly higher than at the surface, indicating that the surface and the marine boundary layer aloft were decoupled due to strongly suppressed vertical mixing in the stable atmosphere over the Gulf of Maine. Intermittent vertical mixing caused by mechanical turbulence was observed on a few occasions resulting in transient ozone spikes at the surface as ozone-rich air was mixed down. Under offshore flow conditions and when the Ronald H. Brown was close to shore, similar ozone values were registered aloft and at the surface, providing evidence that the convectively mixed boundary layer air coming off the land remained well-mixed over the coastal waters. Trajectory analysis using data from land-based and shipborne wind profilers was employed to track the elevated ozone plumes observed with the lidar. Back trajectories revealed that the high-ozone plumes encountered off the coast of northern New England originated predominantly in the Boston and New York City areas. In several cases, these high

  7. Venus - Vertical structure of stratospheric hazes from Mariner 10 pictures

    NASA Technical Reports Server (NTRS)

    Oleary, B.

    1975-01-01

    An 'optical barometer' technique for determining the altitudes of haze in the stratosphere of Venus is presented wherein the Rayleigh-scattering component is derived by comparing orange and UV brightness profiles for nearby Mariner 10 television-picture pairs. The derived scale height for CO2 gas is 4.2 km, corresponding to a temperature of 200 K, in good agreement with radio occultation data. The optical barometer yields a pressure of 4 mb for the level at which the slant-path optical depth at the limb is unity. This level corresponds to a distance from the center of Venus equal to 6131 km, which is accurate to within 1 km provided that there is no appreciable contribution to the brightness by Rayleigh-scattering aerosols which mimic CO2 gas. It is possible that the limb haze layering observed between 6130 and 6140 km could be correlated with temperature inversions detected by the Mariner 5 radio-occultation experiment. A model is proposed wherein the concentration of particles increases rapidly with an effective scale height of about 2 km as one descends about 10 km from the limb haze to the main polarization cloud deck.

  8. Mediterranean intense desert dust outbreaks and their vertical structure based on remote sensing data

    NASA Astrophysics Data System (ADS)

    Gkikas, Antonis; Basart, Sara; Hatzianastassiou, Nikos; Marinou, Eleni; Amiridis, Vassilis; Kazadzis, Stelios; Pey, Jorge; Querol, Xavier; Jorba, Oriol; Gassó, Santiago; Baldasano, José Maria

    2016-07-01

    The main aim of the present study is to describe the vertical structure of the intense Mediterranean dust outbreaks, based on the use of satellite and surface-based retrievals/measurements. Strong and extreme desert dust (DD) episodes are identified at 1° × 1° spatial resolution, over the period March 2000-February 2013, through the implementation of an updated objective and dynamic algorithm. According to the algorithm, strong DD episodes occurring at a specific place correspond to cases in which the daily aerosol optical depth at 550 nm (AOD550 nm) exceeds or equals the long-term mean AOD550 nm (Mean) plus two standard deviations (SD), which is also smaller than Mean+4 × SD. Extreme DD episodes correspond to cases in which the daily AOD550 nm value equals or exceeds Mean+4 × SD. For the identification of DD episodes, additional optical properties (Ångström exponent, fine fraction, effective radius and aerosol index) derived by the MODIS-Terra & Aqua (also AOD retrievals), OMI-Aura and EP-TOMS databases are used as inputs. According to the algorithm using MODIS-Terra data, over the period March 2000-February 2013, strong DD episodes occur more frequently (up to 9.9 episodes year-1) over the western Mediterranean, while the corresponding frequencies for the extreme ones are smaller (up to 3.3 episodes year-1, central Mediterranean Sea). In contrast to their frequency, dust episodes are more intense (AODs up to 4.1), over the central and eastern Mediterranean Sea, off the northern African coasts. Slightly lower frequencies and higher intensities are found when the satellite algorithm operates based on MODIS-Aqua retrievals, for the period 2003-2012. The consistency of the algorithm is successfully tested through the application of an alternative methodology for the determination of DD episodes, which produced similar features of the episodes' frequency and intensity, with just slightly higher frequencies and lower intensities. The performance of the

  9. Vertical density and temperature structure over northern Europe

    NASA Technical Reports Server (NTRS)

    Philbrick, C. R.; Grossmann, K. U.; Hennig, R.; Lange, G.; Offermann, D.; Krankowsky, D.; Schmidlin, F. J.; Von Zahn, U.

    1982-01-01

    Vertical profiles of upper-atmosphere temperature and density over northern Europe constructed from data obtained in November and December 1980, as part of the Energy Budget Campaign, are presented and discussed. Temperature sondes, passive spheres, accelerometers, mass and IR spectrometers, and density gauges were rocket launched from ESRANGE, Sweden and Andoya, Norway; the data are combined with ground measurements to construct 20-120-km-altitude profiles for night periods of severe, moderate, and minimal geomagnetic storm activity. The profiles are compared with each other and with the 1976 U.S. Standard Atmosphere (USSA). In the temperature profiles, increased geomagnetic activity is associated with lower temperatures and flattened profiles in the stratopause region, and higher temperatures in the 70-90-km range. The density profiles show a variation of less than about 15 percent, except for a 25-percent range for the moderate-geomagnetic-activity period. The inferred wavelengths and periods are those expected for internal gravity waves at this altitude, and the divergence from USSA is accounted for by season and latitude dependence.

  10. Structural properties of opals grown with vertical controlled drying.

    PubMed

    Hartsuiker, Alex; Vos, Willem L

    2008-05-01

    We have grown thin opals of self-assembled silica colloids by the well-known vertically controlled drying method. The volume fraction at the start of the growth and the temperature were systematically varied. We have quantitatively characterized the lateral domain sizes by scanning electron microscopy. The sample thickness as a function of position was obtained from Fabry-Pérot fringes measured in optical reflectivity. We observe that the sample thickness strongly increases from top to bottom, independent of temperature, in agreement with a model that we propose. The inhomogeneity in thickness contrasts with earlier reports. The lateral domain shapes of the single-crystal domains are found to vary from irregular near the top to rectangular near the bottom. A surprising observation is that, grosso modo, the lateral domain extents increase linearly with thickness (i.e., thin crystals are small, and thick crystals are large). This behavior agrees qualitatively with results on completely different colloids such as disordered slurries. The consequence of our results for optical applications, including photonic crystals, is that unwanted scattering due to grain boundaries is reduced for large domains that are thick. Conversely, thin crystals will scatter relatively strongly from grain boundaries.

  11. Holistic aerosol evaluation using synthesized aerosol aircraft measurements

    NASA Astrophysics Data System (ADS)

    Watson-Parris, Duncan; Reddington, Carly; Schutgens, Nick; Stier, Philip; Carslaw, Ken; Liu, Dantong; Allan, James; Coe, Hugh

    2016-04-01

    Despite ongoing efforts there are still large uncertainties in aerosol concentrations and loadings across many commonly used GCMs. This in turn leads to large uncertainties in the contributions of the direct and indirect aerosol forcing on climate. However, constraining these fields using earth observation data, although providing global coverage, is problematic for many reasons, including the large uncertainties in retrieving aerosol loadings. Additionally, the inability to retrieve aerosols in or around cloudy scenes leads to further sampling biases (Gryspeerdt 2015). Many in-situ studies have used regional datasets to attempt to evaluate the model uncertainties, but these are unable to provide an assessment of the models ability to represent aerosols properties on a global scale. Within the Global Aerosol Synthesis and Science Project (GASSP) we have assembled the largest collection of quality controlled, in-situ aircraft observations ever synthesized to a consistent format. This provides a global set of in-situ measurements of Cloud Condensation Nuclei (CCN) and Black Carbon (BC), amongst others. In particular, the large number of vertical profiles provided by this aircraft data allows us to investigate the vertical structure of aerosols across a wide range of regions and environments. These vertical distributions are particularly valuable when investigating the dominant processes above or below clouds where remote sensing data is not available. Here we present initial process-based assessments of the BC lifetimes and vertical distributions of CCN in the HadGEM-UKCA and ECHAM-HAM models using this data. We use point-by-point based comparisons to avoid the sampling issues associated with comparing spatio-temporal aggregations.

  12. Vertical and Horizontal Vegetation Structure across Natural and Modified Habitat Types at Mount Kilimanjaro.

    PubMed

    Rutten, Gemma; Ensslin, Andreas; Hemp, Andreas; Fischer, Markus

    2015-01-01

    In most habitats, vegetation provides the main structure of the environment. This complexity can facilitate biodiversity and ecosystem services. Therefore, measures of vegetation structure can serve as indicators in ecosystem management. However, many structural measures are laborious and require expert knowledge. Here, we used consistent and convenient measures to assess vegetation structure over an exceptionally broad elevation gradient of 866-4550 m above sea level at Mount Kilimanjaro, Tanzania. Additionally, we compared (human)-modified habitats, including maize fields, traditionally managed home gardens, grasslands, commercial coffee farms and logged and burned forests with natural habitats along this elevation gradient. We distinguished vertical and horizontal vegetation structure to account for habitat complexity and heterogeneity. Vertical vegetation structure (assessed as number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) displayed a unimodal elevation pattern, peaking at intermediate elevations in montane forests, whereas horizontal structure (assessed as coefficient of variation of number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) was lowest at intermediate altitudes. Overall, vertical structure was consistently lower in modified than in natural habitat types, whereas horizontal structure was inconsistently different in modified than in natural habitat types, depending on the specific structural measure and habitat type. Our study shows how vertical and horizontal vegetation structure can be assessed efficiently in various habitat types in tropical mountain regions, and we suggest to apply this as a tool for informing future biodiversity and ecosystem service studies.

  13. Vertical and Horizontal Vegetation Structure across Natural and Modified Habitat Types at Mount Kilimanjaro.

    PubMed

    Rutten, Gemma; Ensslin, Andreas; Hemp, Andreas; Fischer, Markus

    2015-01-01

    In most habitats, vegetation provides the main structure of the environment. This complexity can facilitate biodiversity and ecosystem services. Therefore, measures of vegetation structure can serve as indicators in ecosystem management. However, many structural measures are laborious and require expert knowledge. Here, we used consistent and convenient measures to assess vegetation structure over an exceptionally broad elevation gradient of 866-4550 m above sea level at Mount Kilimanjaro, Tanzania. Additionally, we compared (human)-modified habitats, including maize fields, traditionally managed home gardens, grasslands, commercial coffee farms and logged and burned forests with natural habitats along this elevation gradient. We distinguished vertical and horizontal vegetation structure to account for habitat complexity and heterogeneity. Vertical vegetation structure (assessed as number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) displayed a unimodal elevation pattern, peaking at intermediate elevations in montane forests, whereas horizontal structure (assessed as coefficient of variation of number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) was lowest at intermediate altitudes. Overall, vertical structure was consistently lower in modified than in natural habitat types, whereas horizontal structure was inconsistently different in modified than in natural habitat types, depending on the specific structural measure and habitat type. Our study shows how vertical and horizontal vegetation structure can be assessed efficiently in various habitat types in tropical mountain regions, and we suggest to apply this as a tool for informing future biodiversity and ecosystem service studies. PMID:26406985

  14. Vertical and Horizontal Vegetation Structure across Natural and Modified Habitat Types at Mount Kilimanjaro

    PubMed Central

    Rutten, Gemma; Ensslin, Andreas; Hemp, Andreas; Fischer, Markus

    2015-01-01

    In most habitats, vegetation provides the main structure of the environment. This complexity can facilitate biodiversity and ecosystem services. Therefore, measures of vegetation structure can serve as indicators in ecosystem management. However, many structural measures are laborious and require expert knowledge. Here, we used consistent and convenient measures to assess vegetation structure over an exceptionally broad elevation gradient of 866–4550m above sea level at Mount Kilimanjaro, Tanzania. Additionally, we compared (human)-modified habitats, including maize fields, traditionally managed home gardens, grasslands, commercial coffee farms and logged and burned forests with natural habitats along this elevation gradient. We distinguished vertical and horizontal vegetation structure to account for habitat complexity and heterogeneity. Vertical vegetation structure (assessed as number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) displayed a unimodal elevation pattern, peaking at intermediate elevations in montane forests, whereas horizontal structure (assessed as coefficient of variation of number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) was lowest at intermediate altitudes. Overall, vertical structure was consistently lower in modified than in natural habitat types, whereas horizontal structure was inconsistently different in modified than in natural habitat types, depending on the specific structural measure and habitat type. Our study shows how vertical and horizontal vegetation structure can be assessed efficiently in various habitat types in tropical mountain regions, and we suggest to apply this as a tool for informing future biodiversity and ecosystem service studies. PMID:26406985

  15. Vertical Electron Transport through PbS-EuS Structures

    NASA Technical Reports Server (NTRS)

    Wrotek, S.; Dybko, K.; Morawski, A.; Makosa, A.; Wosinski, T.; Figielski, T.; Tkaczyk, Z.; Lusakowska, E.; Story, T.; Sipatov, A. Yu

    2003-01-01

    Temperature dependence of current-voltage I-V characteristics and resistivity is studied in ferromagnetic PbS-EuS semiconductor tunnel structures grown on n-PbS (100) substrates. For the structures with a single (2-4 nm thick) ferromagnetic EuS electron barrier we observe strongly non-linear I-V characteristics with an effective tunneling barrier height of 0.3-0.7 eV. The experimentally observed non-monotonic temperature dependence of the (normal to the plane of the structure) electrical resistance of these structures is discussed in terms of the electron tunneling mechanism taking into account the temperature dependent shift of the band offsets at the EuS-PbS heterointerface as well as the exchange splitting of the electronic states at the bottom of the conduction band of EuS.

  16. Reduced-order models for vertical human-structure interaction

    NASA Astrophysics Data System (ADS)

    Van Nimmen, Katrien; Lombaert, Geert; De Roeck, Guido; Van den Broeck, Peter

    2016-09-01

    For slender and lightweight structures, the vibration serviceability under crowd- induced loading is often critical in design. Currently, designers rely on equivalent load models, upscaled from single-person force measurements. Furthermore, it is important to consider the mechanical interaction with the human body as this can significantly reduce the structural response. To account for these interaction effects, the contact force between the pedestrian and the structure can be modelled as the superposition of the force induced by the pedestrian on a rigid floor and the force resulting from the mechanical interaction between the structure and the human body. For the case of large crowds, however, this approach leads to models with a very high system order. In the present contribution, two equivalent reduced-order models are proposed to approximate the dynamic behaviour of the full-order coupled crowd-structure system. A numerical study is performed to evaluate the impact of the modelling assumptions on the structural response to pedestrian excitation. The results show that the full-order moving crowd model can be well approximated by a reduced-order model whereby the interaction with the pedestrians in the crowd is modelled using a single (equivalent) SDOF system.

  17. Vertical-structure effects on planetary microwave brightness temperature measurements - Applications to the lunar regolith

    NASA Technical Reports Server (NTRS)

    Keihm, S. J.; Cutts, J. A.

    1981-01-01

    An attempt to constrain the effects of vertical variations in dielectric properties on lunar microwave observations is presented. A numerical approach for deriving the reflectivity and microwave weighting function of a vertically varying half-space is used, assuming variance in the dielectric properties with depth only, and negligible magnetic effects. The cases of continuous and stratified models of vertical structures are discussed, and a concentration of emitted energy in upper layers is found. The total emitted energy oscillates, varying with the thickness of the upper soil layer, but averaging out interference effects due to random variations in the substrate depth. Consideration is also given to the vertical structure effects on the lunation-mean disk-center brightness temperature, its variations, and the regolith electrical loss, and predicted reflectivity effects by feasible models of the lunar regolith dielectric profile.

  18. The relationship between latent heating, vertical velocity, and precipitation processes: The impact of aerosols on precipitation in organized deep convective systems

    NASA Astrophysics Data System (ADS)

    Tao, Wei-Kuo; Li, Xiaowen

    2016-06-01

    A high-resolution, two-dimensional cloud-resolving model with spectral-bin microphysics is used to study the impact of aerosols on precipitation processes in both a tropical oceanic and a midlatitude continental squall line with regard to three processes: latent heating (LH), cold pool dynamics, and ice microphysics. Evaporative cooling in the lower troposphere is found to enhance rainfall in low cloud condensation nuclei (CCN) concentration scenarios in the developing stages of a midlatitude convective precipitation system. In contrast, the tropical case produced more rainfall under high CCN concentrations. Both cold pools and low-level convergence are stronger for those configurations having enhanced rainfall. Nevertheless, latent heat release is stronger (especially after initial precipitation) in the scenarios having more rainfall in both the tropical and midlatitude environment. Sensitivity tests are performed to examine the impact of ice and evaporative cooling on the relationship between aerosols, LH, and precipitation processes. The results show that evaporative cooling is important for cold pool strength and rain enhancement in both cases. However, ice microphysics play a larger role in the midlatitude case compared to the tropics. Detailed analysis of the vertical velocity-governing equation shows that temperature buoyancy can enhance updrafts/downdrafts in the middle/lower troposphere in the convective core region; however, the vertical pressure gradient force (PGF) is of the same order and acts in the opposite direction. Water loading is small but of the same order as the net PGF-temperature buoyancy forcing. The balance among these terms determines the intensity of convection.

  19. Impacts of regional mixing on the temperature structure of the equatorial Pacific Ocean. Part 1: Vertically uniform vertical diffusion

    NASA Astrophysics Data System (ADS)

    Furue, Ryo; Jia, Yanli; McCreary, Julian P.; Schneider, Niklas; Richards, Kelvin J.; Müller, Peter; Cornuelle, Bruce D.; Avellaneda, Nidia Martínez; Stammer, Detlef; Liu, Chuanyu; Köhl, Armin

    2015-07-01

    We investigate the sensitivity of numerical-model solutions to regional changes in vertical diffusion. Specifically, we vary the background diffusion coefficient, κb, within spatially distinct subregions of the tropical Pacific, assess the impacts of those changes, and diagnose the processes that account for them. Solutions respond to a diffusion anomaly, δκb, in three ways. Initially, there is a fast response (several months), due to the interaction of rapidly-propagating, barotropic and gravity waves with eddies and other mesoscale features. It is followed by a local response (roughly one year), the initial growth and spatial pattern of which can be explained by one-dimensional (vertical) diffusion. At this stage, temperature and salinity anomalies are generated that are either associated with a change in density ("dynamical" anomalies) or without one ("spiciness" anomalies). In a final adjustment stage, the dynamical and spiciness anomalies spread to remote regions by radiation of Rossby and Kelvin waves and by advection, respectively. In near-equilibrium solutions, dynamical anomalies are generally much larger in the latitude band of the forcing, but the impact of off-equatorial forcing by δκb on the equatorial temperature structure is still significant. Spiciness anomalies spread equatorward within the pycnocline, where they are carried to the equator as part of the subsurface branch of the Pacific Subtropical Cells, and spiciness also extends to the equator via western-boundary currents. Forcing near and at the equator generates strong dynamical anomalies, and sometimes additional spiciness anomalies, at pycnocline depths. The total response of the equatorial temperature structure to δκb in various regions depends on the strength and spatial pattern of the generation of each signal within the forcing region as well as on the processes of its spreading to the equator.

  20. Vertical distribution of structural components in corn stover

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In much of the United States, corn (Zea mays L.) stover is the most abundant and widespread agricultural residue. Because of this abundance, stover has been targeted as feedstock for second generation fuel production and other bio-products. Ethanol yield is linked to sugars, while structural compone...

  1. The Vertical Structure of Water Vapor in Mid-latitude as Seen by AIRS, AMSU and ECMWF

    NASA Astrophysics Data System (ADS)

    Fishbein, E.; Fetzer, E.; Hearty, T.; Kahn, B.

    2006-12-01

    The vertical structure of water vapor in mid-latitudes is controlled by Rossby wave activity, especially vertical transport in frontal systems. We compare the vertical structure of water vapor across frontal systems as measured by the Atmospheric Infrared Sounder (AIRS) and the Microwave Humidity Sounder for Brazil (HSB) with fields predicted by the European Center for Medium Range Forecasting (ECMWF) global system and relate these differences to modeling, vertical resolution and sampling errors.

  2. Observed Precipitation Vertical Structure to Support Assumptions used in Satellite Rainfall Retrieval Algorithms

    NASA Astrophysics Data System (ADS)

    Williams, C. R.

    2015-12-01

    Due to a limited number of measurements made on a single space-craft, satellite rainfall retrieval algorithms are under-constrained and often make assumptions about the vertical structure of precipitation. For example, an algorithm may assume the rain rate is constant with height below the freezing level. In order to help support or validate the assumptions used in NASA Global Precipitation Measurement (GPM) satellite rainfall retrieval algorithms, this study investigates the vertical structure of raindrop size distribution (DSD) parameters derived from vertically pointing ground based Doppler radars during GPM field campaigns MC3E (Mid-latitude Continental Convective Clouds Experiment), IFloodS (Iowa Flood Studies), and IPHEX (Integrated Precipitation and Hydrology EXperiment). The three estimated DSD parameters represent the scale and shape of the raindrop size distribution using the parameters: normalized number concentration Nw, mass spectrum mean diameter Dm, and mass spectrum effective variance νm = σm2 / Dm2(mass spectrum variance / mean diameter squared). A vertical pattern in the DSD parameters was often observed during stratiform rain. While the reflectivity was nearly uniform with height, the normalized number concentration (Nw) and mean diameter (Dm) had opposite vertical structures with Nw decreasing and Dm increasing from the melting layer down to the surface. Interestingly, the mass spectrum effective variance (νm) decreased as the raindrops fall indicating that the DSD was evolving into a narrower effective mass spectrum with a loss of small and/or large raindrops. This vertical structure of DSD parameters suggests breakup, coalescence, and evaporation were occurring in the vertical column. In summary, the analysis of vertically pointing radar data during GPM ground validation field campaigns suggests that the net result of breakup, coalescence, and evaporation during stratiform rain appear in the vertical structure of DSD parameters Nw, Dm, and

  3. Vertical variations in the turbulent structure over vineyards

    NASA Astrophysics Data System (ADS)

    Alfieri, J. G.; Kustas, W. P.; Prueger, J. H.; Hipps, L.

    2015-12-01

    Due to their highly-structured canopy, turbulent characteristics within and above vineyards, may not conform to those exhibited by other agricultural and natural ecosystems. As a result, the current generation of land surface models may not adequately describe the turbulent exchange of heat and moisture between the atmosphere and the surface over vineyards. Using data collected during 2014 as a part of the Grape Remote Sensing Atmospheric Profiling and Evapotranspiration Experiment (GRAPEX), an ongoing multi-agency field campaign conducted in the Central Valley of California, this study sought to characterize the variations in the turbulent structure over vineyards. Focusing on unstable daytime conditions, the study compared the turbulent structure at three above-canopy heights: 2.5 m, 3.75 m, and 8 m, agl. Both wavelet and Fourier-based spectral analysis of the wind velocity components indicates a strong tendency for the spectral peak to broaden and shift to lower frequencies as the measurement height increases. Also, beginning with the highest-frequency eddies, the turbulent structure at differing heights become increasingly decoupled as the distance between the measurements increases. In other terms, eddies contributing to a measurement at one height act independently of similarly-sized eddies at another height. As a result, the overall correlation between the turbulent flows measured at differing heights decreases exponential with increasing separation distance. While this effect was seen for all of the periods analyzed, the magnitude of the effect does appear to vary in response to the direction of the wind relative to the vineyard rows.

  4. The impact of temperature vertical structure on trajectory modeling of stratospheric water vapor

    NASA Astrophysics Data System (ADS)

    Wang, T.; Dessler, A. E.; Schoeberl, M. R.; Randel, W. J.; Kim, J.-E.

    2015-03-01

    Lagrangian trajectories driven by reanalysis meteorological fields are frequently used to study water vapor (H2O) in the stratosphere, in which the tropical cold-point temperatures regulate the amount of H2O entering the stratosphere. Therefore, the accuracy of temperatures in the tropical tropopause layer (TTL) is of great importance for understanding stratospheric H2O abundances. Currently, most reanalyses, such as the NASA MERRA (Modern Era Retrospective - analysis for Research and Applications), only provide temperatures with ~ 1.2 km vertical resolution in the TTL, which has been argued to miss finer vertical structure in the tropopause and therefore introduce uncertainties in our understanding of stratospheric H2O. In this paper, we quantify this uncertainty by comparing the Lagrangian trajectory prediction of H2O using MERRA temperatures on standard model levels (traj.MER-T) to those using GPS temperatures at finer vertical resolution (traj.GPS-T), and those using adjusted MERRA temperatures with finer vertical structures induced by waves (traj.MER-Twave). It turns out that by using temperatures with finer vertical structure in the tropopause, the trajectory model more realistically simulates the dehydration of air entering the stratosphere. But the effect on H2O abundances is relatively minor: compared with traj.MER-T, traj.GPS-T tends to dry air by ~ 0.1 ppmv, while traj.MER-Twave tends to dry air by 0.2-0.3 ppmv. Despite these differences in absolute values of predicted H2O and vertical dehydration patterns, there is virtually no difference in the interannual variability in different runs. Overall, we find that a tropopause temperature with finer vertical structure has limited impact on predicted stratospheric H2O.

  5. Surface biofunctionalization and production of miniaturized sensor structures using aerosol printing technologies.

    PubMed

    Grunwald, Ingo; Groth, Esther; Wirth, Ingo; Schumacher, Julian; Maiwald, Marcus; Zoellmer, Volker; Busse, Matthias

    2010-03-01

    The work described in this paper demonstrates that very small protein and DNA structures can be applied to various substrates without denaturation using aerosol printing technology. This technology allows high-resolution deposition of various nanoscaled metal and biological suspensions. Before printing, metal and biological suspensions were formulated and then nebulized to form an aerosol which is aerodynamically focused on the printing module of the system in order to achieve precise structuring of the nanoscale material on a substrate. In this way, it is possible to focus the aerosol stream at a distance of about 5 mm from the printhead to the surface. This technology is useful for printing fluorescence-marked proteins and printing enzymes without affecting their biological activity. Furthermore, higher molecular weight DNA can be printed without shearing. The advantages, such as printing on complex, non-planar 3D structured surfaces, and disadvantages of the aerosol printing technology are also discussed and are compared with other printing technologies. In addition, miniaturized sensor structures with line thicknesses in the range of a few micrometers are fabricated by applying a silver sensor structure to glass. After sintering using an integrated laser or in an oven process, electrical conductivity is achieved within the sensor structure. Finally, we printed BSA in small micrometre-sized areas within the sensor structure using the same deposition system. The aerosol printing technology combined with material development offers great advantages for future-oriented applications involving biological surface functionalization on small areas. This is important for innovative biomedical micro-device development and for production solutions which bridge the disciplines of biology and electronics. PMID:20811121

  6. An analysis of the vertical structure equation for arbitrary thermal profiles

    NASA Technical Reports Server (NTRS)

    Cohn, Stephen E.; Dee, Dick P.

    1987-01-01

    The vertical structure equation is a singular Sturm-Liouville problem whose eigenfunctions describe the vertical dependence of the normal modes of the primitive equations linearized about a given thermal profile. The eigenvalues give the equivalent depths of the modes. The spectrum of the vertical structure equation and the appropriateness of various upper boundary conditions, both for arbitrary thermal profiles were studied. The results depend critically upon whether or not the thermal profile is such that the basic state atmosphere is bounded. In the case of a bounded atmosphere it is shown that the spectrum is always totally discrete, regardless of details of the thermal profile. For the barotropic equivalent depth, which corresponds to the lowest eigen value, upper and lower bounds which depend only on the surface temperature and the atmosphere height were obtained. All eigenfunctions are bounded, but always have unbounded first derivatives. It was proved that the commonly invoked upper boundary condition that vertical velocity must vanish as pressure tends to zero, as well as a number of alternative conditions, is well posed. It was concluded that the vertical structure equation always has a totally discrete spectrum under the assumptions implicit in the primitive equations.

  7. Ensemble-Based Assimilation of Aerosol Observations in GEOS-5

    NASA Technical Reports Server (NTRS)

    Buchard, V.; Da Silva, A.

    2016-01-01

    MERRA-2 is the latest Aerosol Reanalysis produced at NASA's Global Modeling Assimilation Office (GMAO) from 1979 to present. This reanalysis is based on a version of the GEOS-5 model radiatively coupled to GOCART aerosols and includes assimilation of bias corrected Aerosol Optical Depth (AOD) from AVHRR over ocean, MODIS sensors on both Terra and Aqua satellites, MISR over bright surfaces and AERONET data. In order to assimilate lidar profiles of aerosols, we are updating the aerosol component of our assimilation system to an Ensemble Kalman Filter (EnKF) type of scheme using ensembles generated routinely by the meteorological assimilation. Following the work performed with the first NASA's aerosol reanalysis (MERRAero), we first validate the vertical structure of MERRA-2 aerosol assimilated fields using CALIOP data over regions of particular interest during 2008.

  8. Optimal GPS/accelerometer integration algorithm for monitoring the vertical structural dynamics

    NASA Astrophysics Data System (ADS)

    Meng, Xiaolin; Wang, Jian; Han, Houzeng

    2014-11-01

    The vertical structural dynamics is a crucial factor for structural health monitoring (SHM) of civil structures such as high-rise buildings, suspension bridges and towers. This paper presents an optimal GPS/accelerometer integration algorithm for an automated multi-sensor monitoring system. The closed loop feedback algorithm for integrating the vertical GPS and accelerometer measurements is proposed based on a 5 state extended KALMAN filter (EKF) and then the narrow moving window Fast Fourier Transform (FFT) analysis is applied to extract structural dynamics. A civil structural vibration is simulated and the analysed result shows the proposed algorithm can effectively integrate the online vertical measurements produced by GPS and accelerometer. Furthermore, the accelerometer bias and scale factor can also be estimated which is impossible with traditional integration algorithms. Further analysis shows the vibration frequencies detected in GPS or accelerometer are all included in the integrated vertical defection time series and the accelerometer can effectively compensate the short-term GPS outages with high quality. Finally, the data set collected with a time synchronised and integrated GPS/accelerometer monitoring system installed on the Nottingham Wilford Bridge when excited by 15 people jumping together at its mid-span are utilised to verify the effectiveness of this proposed algorithm. Its implementations are satisfactory and the detected vibration frequencies are 1.720 Hz, 1.870 Hz, 2.104 Hz, 2.905 Hz and also 10.050 Hz, which is not found in GPS or accelerometer only measurements.

  9. Surface ozone-aerosol behaviour and atmospheric boundary layer structure in Saharan dusty scenario

    NASA Astrophysics Data System (ADS)

    Adame, Jose; Córdoba-Jabonero, Carmen; Sorrribas, Mar; Gil-Ojeda, Manuel; Toledo, Daniel; Yela, Margarita

    2016-04-01

    A research campaign was performed for the AMISOC (Atmospheric Minor Species relevant to the Ozone Chemistry) project at El Arenosillo observatory (southwest Spain) in May-June 2012. The campaign focused on the impact of Saharan dust intrusions at the Atmospheric Boundary Layer (ABL) and ozone-aerosol interactions. In-situ and remote-sensing techniques for gases and aerosols were used moreover to modelling analyses. Meteorology features, ABL structures and evolution, aerosol profiling distributions and aerosol-ozone interactions on the surface were analysed. Two four-day periods were selected according to non-dusty (clean conditions) and dusty (Saharan dust) situations. In both scenarios, sea-land breezes developed in the lower atmosphere, but differences were found in the upper levels. Results show that surface temperatures were greater than 3°C and humidity values were lower during dusty conditions than non-dusty conditions. Thermal structures on the surface layer (estimated using an instrument on a 100 m tower) show differences, mainly during nocturnal periods with less intense inversions under dusty conditions. The mixing layer during dusty days was 400-800 m thick, less than observed on non-dusty days. Dust also disturbed the typical daily ABL evolution. Stable conditions were observed during the early evening during intrusions. Aerosol extinction on dusty days was 2-3 times higher, and the dust was confined between 1500 and 5500 m. Back trajectory analyses confirmed that the dust had an African origin. On the surface, the particle concentration was approximately 3.5 times higher during dusty events, but the local ozone did not exhibit any change. The arrival of Saharan dust in the upper levels impacted the meteorological surface, inhibited the daily evolution of the ABL and caused an increase in aerosol loading on the surface and at higher altitudes; however, no dust influence was observed on surface ozone.

  10. Aircraft vertical profiles of trace gas and aerosol pollution over the mid-Atlantic United States: Statistics and meteorological cluster analysis

    NASA Astrophysics Data System (ADS)

    Taubman, B. F.; Hains, J. C.; Thompson, A. M.; Marufu, L. T.; Doddridge, B. G.; Stehr, J. W.; Piety, C. A.; Dickerson, R. R.

    2006-05-01

    From 1997 to 2003, airborne measurements of O3, CO, SO2, and aerosol properties were made during summertime air pollution episodes over the mid-Atlantic United States (34.7-44.6°N, 68.4-81.6°W) as part of the Regional Atmospheric Measurement, Modeling, and Prediction Program (RAMMPP). Little diurnal variation was identified in the CO, SO2, and Ångström exponent profiles, although the Ångström exponent profiles decreased with altitude. Boundary layer O3 was greater in the afternoon, while lower free tropospheric O3 was invariant at ˜55 ppbv. The single scattering albedo increased from morning to afternoon (0.93 ± 0.01-0.94 ± 0.01); however, both profiles decreased with altitude. A cluster analysis of back trajectories in conjunction with the vertical profile data was used to identify source regions and characteristic transport patterns during summertime pollution episodes. When the greatest trajectory density lay over the northern Ohio River Valley, the result was large O3 values, large SO2/CO ratios, highly scattering particles, and large aerosol optical depths. Maximum trajectory density over the southern Ohio River Valley resulted in little pollution. The greatest afternoon O3 values occurred during periods of stagnation. North-northwesterly and northerly flow brought the least pollution overall. The contribution of regional transport to afternoon boundary layer O3 was quantified. When the greatest cluster trajectory density lay over the Ohio River Valley (˜59% of the profiles), transport accounted for 69-82% of the afternoon boundary layer O3. Under stagnant conditions (˜27% of the profiles), transport only accounted for 58% of the afternoon boundary layer O3. The results from this study provide a description of regional chemical and transport processes that will be valuable to investigators from the Baltimore, New York, and Pittsburgh EPA Supersites.

  11. Orbiting lidar simulations. I - Aerosol and cloud measurements by an independent-wavelength technique

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Morley, B. M.; Livingston, J. M.; Grams, G. W.; Patterson, E. M.

    1982-01-01

    Aerosol and cloud measurements have been simulated for a Space Shuttle lidar. Expected errors - in signal, transmission, density, and calibration - are calculated algebraically and checked by simulating measurements and retrievals using random-number generators. By day, vertical structure is retrieved for tenuous clouds, Saharan aerosols, and boundary layer aerosols (at 0.53 and 1.06 micron) as well as strong volcanic stratospheric aerosols (at 0.53 micron). By night, all these constituents are retrieved plus upper tropospheric and stratospheric aerosols (at 1.06 micron), mesospheric aerosols (at 0.53 micron), and noctilucent clouds (at 1.06 and 0.53 micron). The vertical resolution was 0.1-0.5 km in the troposphere, 0.5-2.0 km above, except 0.25-1.0 km in the mesospheric cloud and aerosol layers; horizontal resolution was 100-2000 km.

  12. High-Resolution Vertical Observation of Intracellular Structure Using Magnetically Responsive Microplates.

    PubMed

    Teshima, Tetsuhiko; Onoe, Hiroaki; Tottori, Soichiro; Aonuma, Hiroka; Mizutani, Takeomi; Kamiya, Koki; Ishihara, Hirotaka; Kanuka, Hirotaka; Takeuchi, Shoji

    2016-07-01

    A vertical confocal observation system capable of high-resolution observation of intracellular structure is demonstrated. The system consists of magnet-active microplates to rotate, incline, and translate single adherent cells in the applied magnetic field. Appended to conventional confocal microscopes, this system enables high-resolution cross-sectional imaging with single-molecule sensitivity in single scanning. PMID:27185344

  13. Sub-grid Parameterization of Cumulus Vertical Velocities for Climate and Numerical Weather Prediction Models

    NASA Astrophysics Data System (ADS)

    Cooke, William; Donner, Leo

    2015-04-01

    Microphysical and aerosol processes determine the magnitude of climate forcing by aerosol-cloud interactions, are central aspects of cloud-climate feedback, and are important elements in weather systems for which accurate forecasting is a major goal of numerical weather prediction. Realistic simulation of these processes demands not only accurate microphysical and aerosol process representations but also realistic simulation of the vertical motions in which the aerosols and microphysics act. Aerosol activation, for example, is a strong function of vertical velocity. Cumulus parameterizations for climate and numerical weather prediction models have recently begun to include vertical velocities among the statistics they predict. These vertical velocities have been subject to only limited evaluation using observed vertical velocities. Deployments of multi-Doppler radars and dual-frequency profilers in recent field campaigns have substantially increased the observational base of cumulus vertical velocities, which for decades had been restricted mostly to GATE observations. Observations from TWP-ICE (Darwin, Australia) and MC3E (central United States) provide previously unavailable information on the vertical structure of cumulus vertical velocities and observations in differing synoptic contexts from those available in the past. They also provide an opportunity to independently evaluate cumulus parameterizations with vertical velocities tuned to earlier GATE observations. This presentation will compare vertical velocities observed in TWP-ICE and MC3E with cumulus vertical velocities using the parameterization in the GFDL CM3 climate model. Single-column results indicate parameterized vertical velocities are frequently greater than observed. Errors in parameterized vertical velocities exhibit similarities to vertical velocities explicitly simulated by cloud-system resolving models, and underlying issues in the treatment of microphysics may be important for both. The

  14. Coarse-fine vertical scanning based optical profiler for structured surface measurement with large step height

    NASA Astrophysics Data System (ADS)

    Zheng, Yi; Liu, Xiaojun; Lei, Zili; Li, Qian; Yang, Xiao; Chen, Liangzhou; Lu, Wenlong

    2015-02-01

    White light interference (WLI) optical profiler had been used widely for structured surface measurement. To achieve high measuring accuracy, piezoelectric ceramic (PZT) was usually used as the vertical scanning unit, which was normally less than 100um and only for small range structured surface measurement. With the development of advanced manufacturing technology, precision structured surfaces with large step height were appearing. To satisfy the measurement requirements of this kind of precision structured surfaces, WLI optical profiler with large range had to be developed. In this paper, an optical profiler was proposed, in which a coarse-fine vertical scanning system was adopted to expand its measurement range to 10mm while its resolution still at nanometer level.

  15. Synthesis and structural characterization of vertical ferromagnetic MnAs/semiconducting InAs heterojunction nanowires

    NASA Astrophysics Data System (ADS)

    Kodaira, Ryutaro; Hara, Shinjiro; Kabamoto, Kyohei; Fujimagari, Hiromu

    2016-07-01

    The purpose of this study is to synthesize vertical ferromagnetic/semiconducting heterojunction nanowires by combing the catalyst-free selective-area growth of InAs nanowires and the endotaxial nanoclustering of MnAs and to structurally and magnetically characterize them. MnAs penetrates the InAs nanowires to form nanoclusters. The surface migration length of manganese adatoms on the nanowires, which is estimated to be 600 nm at 580 °C, is a key to the successful fabrication of vertical MnAs/InAs heterojunction nanowires with atomically abrupt heterointerfaces.

  16. Intercomparison of aerosol extinction profiles retrieved from MAX-DOAS measurements

    NASA Astrophysics Data System (ADS)

    Frieß, U.; Klein Baltink, H.; Beirle, S.; Clémer, K.; Hendrick, F.; Henzing, B.; Irie, H.; de Leeuw, G.; Li, A.; Moerman, M. M.; van Roozendael, M.; Shaiganfar, R.; Wagner, T.; Wang, Y.; Xie, P.; Yilmaz, S.; Zieger, P.

    2016-07-01

    A first direct intercomparison of aerosol vertical profiles from Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations, performed during the Cabauw Intercomparison Campaign of Nitrogen Dioxide measuring Instruments (CINDI) in summer 2009, is presented. Five out of 14 participants of the CINDI campaign reported aerosol extinction profiles and aerosol optical thickness (AOT) as deduced from observations of differential slant column densities of the oxygen collision complex (O4) at different elevation angles. Aerosol extinction vertical profiles and AOT are compared to backscatter profiles from a ceilometer instrument and to sun photometer measurements, respectively. Furthermore, the near-surface aerosol extinction coefficient is compared to in situ measurements of a humidity-controlled nephelometer and dry aerosol absorption measurements. The participants of this intercomparison exercise use different approaches for the retrieval of aerosol information, including the retrieval of the full vertical profile using optimal estimation and a parametrised approach with a prescribed profile shape. Despite these large conceptual differences, and also differences in the wavelength of the observed O4 absorption band, good agreement in terms of the vertical structure of aerosols within the boundary layer is achieved between the aerosol extinction profiles retrieved by the different groups and the backscatter profiles observed by the ceilometer instrument. AOTs from MAX-DOAS and sun photometer show a good correlation (R>0.8), but all participants systematically underestimate the AOT. Substantial differences between the near-surface aerosol extinction from MAX-DOAS and from the humidified nephelometer remain largely unresolved.

  17. Global Aerosol Distributions Derived From the CALIPSO Observations

    NASA Astrophysics Data System (ADS)

    Kittaka, C.; Winker, D.; Omar, A.; Liu, Z.; Vaughan, M.; Trepte, C.

    2008-12-01

    Since June 2006, CALIPSO continues to provide routine and systematic measurements of lidar backscatter at two wavelengths, 532 and 1064 nm. As an active sensor, the quality of the measurement is nearly insensitive to surface properties allowing quantitative measurements in regions that are problematic to passive sensors. In particular, aerosol and cloud observations in the polar regions and desert areas are possible with the CALIPSO lidar through the different seasons of a year. The CALIPSO level 2 products, which include aerosol and cloud vertical profiles along tracks, reveal, for the first time, the multi-layer structure of aerosols and clouds on a global scale. This allows not only a depiction of aerosols in relation to clouds, but also the investigation of the interaction between aerosols and clouds. In this study, we present global distributions of aerosol in terms of season, layer height, aerosol species, and in relation to clouds using two years of CALIPSO observations. The CALIPSO aerosol extinction data sets under clear sky are evaluated against the AERONET aerosol optical depth (AOD) and the MODIS AOD collection 5 data sets. The agreement and discrepancies from these comparisons are characterized regionally and investigated using other CALIPSO observable and retrieved parameters. Furthermore, aerosols above clouds and in the vicinity of clouds are examined on a global scale. The implications for aerosol radiative forcing are discussed, highlighting the new and interesting aerosol features obtained from CALIPSO observations.

  18. Agglomeration due to Brownian motion of fractal-structured combustion aerosols

    SciTech Connect

    Kaplan, C.H.

    1987-01-01

    A dynamic Monte-Carlo type lattice model has been developed to simulate the agglomeration of non-spherical chain-line aggregate combustion aerosols due to Brownian motion. Simulations are carried out in the free molecular and continuum regimes, for both initial monodisperse and initial log-normally distributed aerosols, with and without source mechanisms. Preservation of the chain-like structure of the aggregate is accomplished throughout the simulation by describing the agglomerate as fractal, that is, scale-invariant, self-similar with a noninteger dimensionality. Simulation results indicate that cluster growth is more rapid in the free molecular regime than in the continuum. Aerosols and log-normal distributions retain their log-normal characteristics even after long coagulation times. The effect of the clusters' fractal dimension on the cluster growth rate is determined; the rate of agglomeration increases when the structure of the agglomerate is more fragmented (lower fractal dimension). An analytical solution to the coagulation equation is obtained for log-normal aerosols by calculating moments of the distribution and solving sets of moment equations to determine the size distribution parameters. Condition numbers are employed to determine which moments should be calculated to most accurately determine these parameters. Excellent agreement is obtained between the simulations and the solution to the moment equations. Experimental measurements of soot particle velocity in a premixed methane/air flame are made using laser Doppler velocimetry.

  19. Vertical aerosol structure of Neptune - Constraints from center-to-limb profiles

    NASA Astrophysics Data System (ADS)

    Hammel, H. B.; Baines, K. H.; Bergstralh, J. T.

    1989-08-01

    New center-to-limb (CTL) equatorial region profiles of Neptune have been extracted from spatially well-resolved images. The 8900-A CTL profile entails the presence of material above the 5-mbar level whose optical depth is less than 0.5. CH4-band data admit of thin scattering hazes in the 0.4-1.5 bar pressure level, although optical depths must be lower than 0.05; so thin a haze falls short of the reflected flux at 6340 A, thereby implying the presence of another scattering layer deeper than 1.5 bars. A good fit to the observed reflectivity is obtained by a bright cloud layer with an optical depth of 3.0.

  20. Inter-comparison of MAX-DOAS Retrieved Vertical Profiles of Aerosol Extinction, SO2 and NO2 in the Alberta Oil Sands with LIDAR Data and GEM-MACH Air Quality Model.

    NASA Astrophysics Data System (ADS)

    Davis, Zoe; Friess, Udo; Strawbridge, Kevin; Whiteway, James; Aggarwal, Monika; Makar, Paul; Li, Shao-Meng; O'Brien, Jason; Baray, Sabour; Schnitzler, Elijah; Olfert, Jason S.; Osthoff, Hans D.; Lobo, Akshay; McLaren, Robert

    2016-04-01

    Understanding industrial emissions of trace gas pollutants in the Alberta oil sands is essential to maintaining air quality standards and informing public policy. Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements of trace gases can improve knowledge of pollutant levels, vertical distribution and chemical transformation. During an intensive air measurement campaign to study emissions, transport, transformation and deposition of oil sands air pollutants from August to September of 2013, a MAX-DOAS instrument was deployed at a site north of Fort McMurray, Alberta to determine the vertical profiles of aerosol extinction, NO2 and SO2 through retrieval from the MAX-DOAS spectral measurements using an optimal estimation method. The large complement of data collected from multiple instruments deployed during this field campaign provides a unique opportunity to validate and characterize the performance of the MAX-DOAS vertical profile retrievals. Aerosol extinction profiles determined from two Light Detection and Ranging (LIDAR) instruments, one collocated and the other on a Twin Otter aircraft that flew over the site during the study, will be compared to the MAX-DOAS aerosol extinction profile retrievals. Vertical profiles of NO2 and SO2 retrieved from the MAX-DOAS measurements will be further compared with the composite vertical profiles measured from the flights of a second aircraft, the NRC-Convair 580, over the field site during the same measurement period. Finally, the MAX-DOAS retrieved tropospheric vertical column densities (VCDs) of SO2 and NO2 will be compared to the predicted VCDs from Environment and Climate Change Canada's Global Environmental Multi-scale - Modelling Air quality and Chemistry (GEM-MACH) air quality model over the grid cell containing the field site. Emission estimates of SO2 from the major oil mining facility Syncrude Mildred Lake using the MAX-DOAS VCD results, validated through the detailed characterization above

  1. Vertical columns of NO2, HONO, HCHO, CHOCHO and aerosol extinction: diurnal and seasonal variations in context of CalNex and CARES

    NASA Astrophysics Data System (ADS)

    Ortega, I.; Coburn, S.; Oetjen, H.; Sinreich, R.; Thalman, R. M.; Waxman, E.; Volkamer, R.

    2011-12-01

    We present results from two ground-based University of Colorado Multi Axis Differential Optical Absorption Spectroscopy (CU-MAX-DOAS) instruments that were deployed during the CALNEX and CARES 2010 field campaigns. Ground based CU-MAX-DOAS measurements were carried out through Dec 2010, and measured vertical column abundances of nitrogen dioxide (NO2), nitrous acid (HONO), formaldehyde (HCHO), glyoxal (CHOCHO), and aerosol extinction, which is determined indirectly from observing the oxygen dimers (O4). The measurements were acquired on the top of Millikan library at Caltech, Pasadena, CA, at the Fontana Arrows site located 60 Km east of Caltech, and for a limited period also downwind of Sacramento at T1 site during CARES. In the South Coast Air Basin, the MAX-DOAS instruments at both sites collected an extended time series of use to test satellites, and atmospheric chemistry models. We determine the state of the planetary boundary layer by comparing the columns observations with in-situ sensors, and place the CALNEX and CARES measurements intensive into seasonal context.

  2. The Vertical Structure of Major Meteorological Features on Jupiter: The Great Red Spot and White Ovals BC and DE

    NASA Technical Reports Server (NTRS)

    Baines, Kevin H.; Carlson, Robert W.

    1999-01-01

    Multi-spectral imagery of Jupiter's Great Red Spot (GRS) and two White ovals acquired by the Galileo/NIMS are used to constrain the spatial variability of the vertical aerosol structure and the distribution of ammonia in and around these most-prominent anti-cyclonic features. All three features exhibit a high-altitude core spanning about 3/4 of their visual size when viewed with moderate absorption wavelengths, indicating a bulk elliptical, "wedding cake" shape in their overall three-dimensional cloud structure. A distinctive spiral pattern within the GRS core is seen in moderate methane and hydrogen absorption bandpasses. This pattern - which has been modelled to show a 2 km variation in cloudtop pressure within the GRS - is inconsistent with a different spiral-shaped pattern observed in ammonia-sensitive wavelengths, thus indicating spatial variability not only in the column abundance of ammonia within the GRS, but in its mixing ratio as well. White Ovals BC and DE were observed in February 1997, just a year before their unusual merger into a single feature. At the time of these observations, the centers of the two anti-cyclones were about 16 degrees apart, separated by a complex cyclonic feature which exhibited unusual spatial variability in its appearance in images acquired at ammonia-sensitive wavelengths. In particular, the northern half of this feature has the largest ammonia column abundance seen within the environs around the white ovals, indicating unusual variability in either cloud structure/altitude and/or ammonia humidity within the cyclone.

  3. CVD growth of graphene under exfoliated hexagonal boron nitride for vertical hybrid structures

    SciTech Connect

    Wang, Min; Jang, Sung Kyu; Song, Young Jae; Lee, Sungjoo

    2015-01-15

    Graphical abstract: We have demonstrated a novel yet simple method for fabricating graphene-based vertical hybrid structures by performing the CVD growth of graphene at an h-BN/Cu interface. Our systematic Raman measurements combined with plasma etching process indicate that a graphene film is grown under exfoliated h-BN rather than on its top surface, and that an h-BN/graphene vertical hybrid structure has been fabricated. Electrical transport measurements of this h-BN/graphene, transferred on SiO2, show the carrier mobility up to approximately 2250 cm{sup 2} V{sup −1} s{sup −1}. The developed method would enable the exploration of the possibility of novel hybrid structure integration with two-dimensional material systems. - Abstract: We have demonstrated a novel yet simple method for fabricating graphene-based vertical hybrid structures by performing the CVD growth of graphene at an h-BN/Cu interface. Our systematic Raman measurements combined with plasma etching process indicate that a graphene film is grown under exfoliated h-BN rather than on its top surface, and that an h-BN/graphene vertical hybrid structure has been fabricated. Electrical transport measurements of this h-BN/graphene, transferred on SiO{sub 2}, show the carrier mobility up to approximately 2250 cm{sup 2} V{sup −1} s{sup −1}. The developed method would enable the exploration of the possibility of novel hybrid structure integration with two-dimensional material systems.

  4. Sea Spray Aerosol Structure and Composition Using Cryogenic Transmission Electron Microscopy

    PubMed Central

    2016-01-01

    The composition and surface properties of atmospheric aerosol particles largely control their impact on climate by affecting their ability to uptake water, react heterogeneously, and nucleate ice in clouds. However, in the vacuum of a conventional electron microscope, the native surface and internal structure often undergo physicochemical rearrangement resulting in surfaces that are quite different from their atmospheric configurations. Herein, we report the development of cryogenic transmission electron microscopy where laboratory generated sea spray aerosol particles are flash frozen in their native state with iterative and controlled thermal and/or pressure exposures and then probed by electron microscopy. This unique approach allows for the detection of not only mixed salts, but also soft materials including whole hydrated bacteria, diatoms, virus particles, marine vesicles, as well as gel networks within hydrated salt droplets—all of which will have distinct biological, chemical, and physical processes. We anticipate this method will open up a new avenue of analysis for aerosol particles, not only for ocean-derived aerosols, but for those produced from other sources where there is interest in the transfer of organic or biological species from the biosphere to the atmosphere. PMID:26878061

  5. Modelling Aerosol Dispersion in Urban Street Canyons

    NASA Astrophysics Data System (ADS)

    Tay, B. K.; Jones, D. P.; Gallagher, M. W.; McFiggans, G. B.; Watkins, A. P.

    2009-04-01

    Flow patterns within an urban street canyon are influenced by various micrometeorological factors. It also represents an environment where pollutants such as aerosols accumulate to high levels due to high volumes of traffic. As adverse health effects are being attributed to exposure to aerosols, an investigation of the dispersion of aerosols within such environments is of growing importance. In particular, one is concerned with the vertical structure of the aerosol concentration, the ventilation characteristics of the street canyon and the influence of aerosol microphysical processes. Due to the inherent heterogeneity of the aerosol concentrations within the street canyon and the lack of spatial resolution of measurement campaigns, these issues are an on-going debate. Therefore, a modelling tool is required to represent aerosol dispersion patterns to provide insights to results of past measurement campaigns. Computational Fluid Dynamics (CFD) models are able to predict detailed airflow patterns within urban geometries. This capability may be further extended to include aerosol dispersion, by an Euler-Euler multiphase approach. To facilitate the investigation, a two-dimensional, multiphase CFD tool coupled with the k-epsilon turbulence model and with the capability of modelling mixed convection flow regimes arising from both wind driven flows and buoyancy effects from heated walls was developed. Assuming wind blowing perpendicularly to the canyon axis and treating aerosols as a passive scalar, an attempt will be made to assess the sensitivities of aerosol vertical structure and ventilation characteristics to the various flow conditions. Numerical studies were performed using an idealized 10m by 10m canyon to represent a regular canyon and 10m by 5m to represent a deep one. An aerosol emission source was assigned on the centerline of the canyon to represent exhaust emissions. The vertical structure of the aerosols would inform future directives regarding the

  6. Improving Canopy Vertical Structure Measurements with Dual-Wavelength Laser Scanning

    NASA Astrophysics Data System (ADS)

    Li, Z.; Strahler, A. H.; Schaaf, C.; Jupp, D. L. B.; Howe, G.; Hewawasam, K.; Chakrabarti, S.; Cook, T.; Paynter, I.; Saenz, E. J.; Yang, X.; Yao, T.

    2015-12-01

    Forest canopy structure regulates radiation interception through the canopy, affects the canopy microclimate, and consequently influences the energy, water, and carbon fluxes between soil, vegetation and atmosphere through its interaction with leaf physiological functioning. To observe vertical canopy forest structure in finer and more accurate detail, we retrieved vertical profiles of leaf and woody components separately with a terrestrial laser scanner, the Dual-Wavelength Echidna Lidar (DWEL). DWEL scans of a hardwood site at the Harvard Forest, Petersham, Massachusetts, USA, in early May and in late September in 2014, revealed the spatial heterogeneity of the canopy vertical structure of the two vegetation components: leaves and woody materials. The DWEL collects simultaneous scans of forests with two lasers at different wavelengths, 1064 nm (NIR) and 1548 nm (SWIR). Power returned from leaves is much lower than from woody materials such as trunks and branches at the SWIR wavelength due to the liquid water absorption by leaves, whereas returned power at the NIR wavelength is similar from both leaves and woody materials. This spectral contrast between leaves and woody materials, along with spatial context information. discriminates leaves and woody materials accurately in 3-D space, thus allowing the measurement of separate leaf and woody area profiles. We also captured the change in the canopy vertical structure over the seven years by a comparison between the current measurements by the DWEL in 2014 and past measurements in 2007 at the same site by the DWEL's predecessor, a single-wavelength terrestrial lidar, the Echidna Validation Instrument. The comparison also demonstrates the advantage of dual-wavelength laser scanning by the DWEL for canopy structure measurements.

  7. Influence of density stratification and bottom depth on vertical mode structure functions in the tropical Pacific

    NASA Astrophysics Data System (ADS)

    Picaut, JoëL.; Sombardier, Laurence

    1993-01-01

    Vertical mode structure functions are computed over the entire tropical Pacific Ocean (30°N to 30°S) by using the Levitus temperature-salinity climatological file and a National Oceanic and Atmospheric Administration bathymetry file and over a few selected areas of the Pacific by using a more accurate conductivity-salinity temperature depth (CTD-STD) file. At every 1° grid point of the tropical Pacific, phase speeds of the first five modes are estimated from the Levitus density profiles and the actual bottom depth. They range from 305 to 195 cm s-1 for mode 1 to 65 to 40 cm s-1 for mode 5. Because of the coarse vertical resolution in the Levitus profiles, the corresponding phase speeds are underestimated by about 8% compared to phase speeds calculated with CTD-STD profiles. In order to estimate the relative importance of density stratification and bottom depth on vertical mode structure functions, two sets of modes are calculated. The first set is calculated with the Levitus density profiles truncated or extended to a mean basin bottom depth (3570 m) at every grid point. The resulting modes are representative of the influence of density stratification on modal calculations. The second set is computed with a mean basin density profile and the actual bottom depth at every grid point. This set represents the influence of bottom depth. Phase speed comparison between these two sets of modes and the original modes indicates that for the first two modes, the bottom depth contribution is an order of magnitude less than the density contribution. For modes 3 and 4, the bottom depth contribution increases, and for mode 5 it is almost equal to the density contribution. The relative importance of deep density stratification and upper layer stratification on vertical mode structure functions is evaluated by using the more accurate CTD-STD file. This study is restricted to a few small areas with enough deep profiles, taken within a few days, to ensure proper statistical

  8. Vertical distribution of optical parameters of aerosol, evaluation of rain rate and rain drop size by using the pal system, at guwahati

    NASA Astrophysics Data System (ADS)

    Devi, M.; Barbara, A. K.; Baishya, R.; Takeuchi, N.

    The paper gives in brief, the features of a Portable Automated Lidar (PAL) set up, fabricated and operated at Guwahati (260N and 920 E) a subtropical station, for monitoring of aerosol, cloud and precipitation features and then describes the method adopted for profiling of aerosol and determination of rain rate as well as drop sizes with coupled observation from distrometer and radiosonde. The PAL generates 532 nm laser pulses of 10 ns duration of high repetition rate of 1-2 kHz. The backscattered signals from atmospheric constituents collected by a telescope of diameter 20 cm., and amplified with a Photo Multiplier Tube (PMT), are then processed in Lab View environment by a software for, extracting aerosol and cloud features. For checking and correcting the alignment affected by temperature, provisions are also introduced for easy adjustment of horizontal and vertical axes. In this approach we have evaluated system constant C, from the lidar backscattered signal itself, for an assumed lidar ratio as a first approach, and with extinction co-efficient determined experimentally. Here, the lidar is put for probing the atmosphere horizontally, when we may assume the atmosphere to be homogeneous along the FOV of the lidar. However, as horizontal in-homogeneity of the atmosphere cannot be ruled out, the paper illustrates the type of profiles adopted for such analysis and the lidar being situated in a semi rural area, a methodical screening approach adopted for selection of echograms free from shoot and fossil burning by product is described. Once the backscatter power with distance is known from the selected lidar outputs, σ is evaluated from the slope of the profile associating ``ratio of backscatter power to transmitter power'' with distance r. The methods taken up for realization of β value and then determination of C are elaborated in the paper. The lidar ratio S, is assumed from reported results as a first reference value. This parameter S is then checked for its

  9. Advanced BCD technology with vertical DMOS based on a semi-insulation structure

    NASA Astrophysics Data System (ADS)

    Kui, Ma; Xinghua, Fu; Jiexin, Lin; Fashun, Yang

    2016-07-01

    A new semi-insulation structure in which one isolated island is connected to the substrate was proposed. Based on this semi-insulation structure, an advanced BCD technology which can integrate a vertical device without extra internal interconnection structure was presented. The manufacturing of the new semi-insulation structure employed multi-epitaxy and selectively multi-doping. Isolated islands are insulated with the substrate by reverse-biased PN junctions. Adjacent isolated islands are insulated by isolation wall or deep dielectric trenches. The proposed semi-insulation structure and devices fixed in it were simulated through two-dimensional numerical computer simulators. Based on the new BCD technology, a smart power integrated circuit was designed and fabricated. The simulated and tested results of Vertical DMOS, MOSFETs, BJTs, resistors and diodes indicated that the proposed semi-insulation structure is reasonable and the advanced BCD technology is validated. Project supported by the National Natural Science Foundation of China (No. 61464002), the Science and Technology Fund of Guizhou Province (No. Qian Ke He J Zi [2014]2066), and the Dr. Fund of Guizhou University (No. Gui Da Ren Ji He Zi (2013)20Hao).

  10. VERTICAL STRUCTURE AND CORONAL POWER OF ACCRETION DISKS POWERED BY MAGNETOROTATIONAL-INSTABILITY TURBULENCE

    SciTech Connect

    Uzdensky, Dmitri A.

    2013-10-01

    In this paper, we consider two outstanding intertwined problems in modern high-energy astrophysics: (1) the vertical-thermal structure of an optically thick accretion disk heated by the dissipation of magnetohydrodynamic turbulence driven by the magnetorotational instability (MRI), and (2) determining the fraction of the accretion power released in the corona above the disk. For simplicity, we consider a gas-pressure-dominated disk and assume a constant opacity. We argue that the local turbulent dissipation rate due to the disruption of the MRI channel flows by secondary parasitic instabilities should be uniform across most of the disk, almost up to the disk photosphere. We then obtain a self-consistent analytical solution for the vertical thermal structure of the disk, governed by the balance between the heating by MRI turbulence and the cooling by radiative diffusion. Next, we argue that the coronal power fraction is determined by the competition between the Parker instability, viewed as a parasitic instability feeding off of MRI channel flows, and other parasitic instabilities. We show that the Parker instability inevitably becomes important near the disk surface, leading to a certain lower limit on the coronal power. While most of the analysis in this paper focuses on the case of a disk threaded by an externally imposed vertical magnetic field, we also discuss the zero net flux case, in which the magnetic field is produced by the MRI dynamo itself, and show that most of our arguments and conclusions should be valid in this case as well.

  11. On the vertical structure and spectral characteristics of the marine Low-Level Jet

    NASA Astrophysics Data System (ADS)

    Helmis, C. G.; Sgouros, G.; Wang, Q.

    2015-01-01

    The aim of this work is the study of the vertical structure and the spectral characteristics of the marine Low Level Jets (LLJs) which are associated with frontal events. The analyzed data are based on remote sensing (sodar) and in-situ instrumentation measurements, performed during summer 2003, in the frame of the Coupled Boundary Layers Air-Sea Transfer Experiment in Low Winds (CBLAST-Low), at Nantucket Island, MA, U.S.A. The study of the vertical structure of the lower marine Atmospheric Boundary Layer (MABL), during a ten day period, has shown that the first 100 to 200 m, is characterized by strongly stable atmospheric conditions which are modified to slightly stable or almost neutral at higher levels. The frequent development of LLJs was also observed and was associated with frontal events, depending on the meteorological conditions. In order to understand the influence of the different physical processes and to study the vertical distribution of the wind intensity variations at the various time scales of interest, the Hilbert-Huang Transform (HHT) algorithm was applied to the time series of the wind data from the sodar, at different levels. Results are presented and discussed for certain LLJ cases, where the observed LLJs were persistent for several hours or days while the analysis of the wind speed data showed high amplitude variations corresponding to contributions not only from inertial but also from diurnal and meso-scale motions.

  12. Forced vibration analysis of rotating structures with application to vertical axis wind turbines

    NASA Astrophysics Data System (ADS)

    Lobitz, D. W.

    Predictive methods for the dynamic analysis of wind turbine systems are important for assessing overall structural integrity and fatigue life. For the former, the identification of resonance points (spectral analysis) is of primary concern. For the latter forced vibration analysis is necessary. These analyses are complicated by the fact that, for a spinning turbine, the stress-producing deformations take place in both fixed and rotating reference systems simultaneously. As an example, the tower of a horizontal axis wind turbine (HAWT) must be analyzed in a fixed frame, and the rotor in a rotating one. Forced vibration analysis is further complicated in that accurate models need to be developed for aeroload prediction. Methods which are available for forced vibration analysis of both horizontal and vertical axis machines are identified and the method which was developed for vertical axis wind turbines is emphasized, with some comparisons of the predictions to experimental data.

  13. High-power narrow-vertical-divergence photonic band crystal laser diodes with optimized epitaxial structure

    SciTech Connect

    Liu, Lei; Qu, Hongwei; Liu, Yun; Zhang, Yejin; Zheng, Wanhua; Wang, Yufei; Qi, Aiyi

    2014-12-08

    900 nm longitudinal photonic band crystal (PBC) laser diodes with optimized epitaxial structure are fabricated. With a same calculated fundamental-mode divergence, stronger mode discrimination is achieved by a quasi-periodic index modulation in the PBC waveguide than a periodic one. Experiments show that the introduction of over 5.5 μm-thick PBC waveguide contributes to only 10% increment of the internal loss for the laser diodes. For broad area PBC lasers, output powers of 5.75 W under continuous wave test and over 10 W under quasi-continuous wave test are reported. The vertical divergence angles are 10.5° at full width at half maximum and 21.3° with 95% power content, in conformity with the simulated angles. Such device shows a prospect for high-power narrow-vertical-divergence laser emission from single diode laser and laser bar.

  14. Formulation of human-structure interaction system models for vertical vibration

    NASA Astrophysics Data System (ADS)

    Caprani, Colin C.; Ahmadi, Ehsan

    2016-09-01

    In this paper, human-structure interaction system models for vibration in the vertical direction are considered. This work assembles various moving load models from the literature and proposes extension of the single pedestrian to a crowd of pedestrians for the FE formulation for crowd-structure interaction systems. The walking pedestrian vertical force is represented as a general time-dependent force, and the pedestrian is in turn modelled as moving force, moving mass, and moving spring-mass-damper. The arbitrary beam structure is modelled using either a formulation in modal coordinates or finite elements. In each case, the human-structure interaction (HSI) system is first formulated for a single walking pedestrian and then extended to consider a crowd of pedestrians. Finally, example applications for single pedestrian and crowd loading scenarios are examined. It is shown how the models can be used to quantify the interaction between the crowd and bridge structure. This work should find use for the evaluation of existing and new footbridges.

  15. Vertical structure and variation of currents observed in autumn in the Korea Strait

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Ho; Choi, Byoung-Ju

    2015-06-01

    To observe vertical structure and temporal variations of currents in the Tsushima Warm Current region of the Korea Strait, a moored buoy system was deployed in autumn 2009. The moored buoy system measured vertical profiles of current, temperature, and salinity for 24 days and a background hydrographic survey was performed. Along-strait northeastward currents were dominant in the upper layer (8-35 m). The mean current veers counterclockwise from 48 m to 74 m as much as 50°, and its speed is reduced with depth. There were distinct northward onshore currents near the bottom (65-80 m). It was demonstrated that thermal wind relation holds in the inclined pycnocline layer, which generates the counterclockwise veering current structure. Density gradient along the strait is a main factor producing the cross-strait onshore current component below the upper-layer and the cross-strait density gradient reduces the along-strait current component with depth. Previous studies have never focused on the effect of the along-strait density structure on current structure. The first Empirical Orthogonal Function mode (CM1) of current variability explains 70% of local current variations and its vertical structure is close to the mean current structure. The correlation analysis among variations of CM1 current, slope of sea level anomaly (SSLA) and local wind anomaly revealed that the variation of CM1 current is mainly related to the variation of SSLA across the strait (c-SSLA), which is known to be controlled by remote and local wind forcing. Similarity between vertical structures of mean and CM1 current suggests that thermal wind relation is the main dynamics maintaining the counterclockwise turning of CM1 current below the upper layer although the upperlayer CM1 current is controlled by c-SSLA through barotropic geostrophic relation. Time series of temperature and salinity indicate that the thermohaline front between Korean Coastal Water and Tsushima Warm Current Water meanders in

  16. Vertical structure of atmospheric moisture in the Arctic and its linkages to the clouds

    NASA Astrophysics Data System (ADS)

    Nygård, Tiina; Vihma, Timo; Valkonen, Teresa

    2016-04-01

    Much of the moisture in the Arctic is transported from the lower latitudes as evaporation is typically small over snow and ice-covered surfaces. There has been a large uncertainty on the altitude at which the moisture transport peaks in the Arctic, although the peak altitude of moisture transport has presumably a remarkable importance for the cloud climatology and properties as well on the clear-sky radiation. Here we present results on the vertical structure of the atmospheric moisture and its transport to the Arctic, including seasonal and spatial differences, based on ERA-Interim and JRA-55 reanalysis data as well as on radiosoundings from 36 stations in the circumpolar Arctic. The study period is from 2000 to 2014. We investigate the vertical structure of horizontal moisture transport to the Arctic by dividing the atmosphere into several vertical layers and calculating moisture flux in each of them separately. Based on the variability of results between the data sets (two different reanalyses and radiosoundings), level of uncertainty in moisture transport estimates is also defined. We also present climatology and characteristics of humidity inversions, i.e., layers where specific humidity increases with height, in the Arctic, including their relationship with cloud cover. Vertically uneven moisture advection is probably a significant generator of very common humidity inversion layers observed in the Arctic lower troposphere. These humidity inversions have in recent studies been demonstrated to offer a potential moisture source aloft for cloud formation and maintenance. Considering the commonness of the elevated humidity inversions in the Arctic troposphere, there is a strong reason to believe that humidity inversions have a high importance for clouds in wide spatial and temporal scales, and they possibly largely contribute to the spatially extensive cloud cover in the Arctic. The results encourage for further studies on interactions between humidity inversions

  17. Vertical thermo-haline structure of the Baltic Sea cold intermediate layer

    NASA Astrophysics Data System (ADS)

    Stepanova, Natalya

    2016-04-01

    Main characteristic features of vertical thermo-haline structure of the cold intermediate layer (CIL) of the Baltic Sea are identified on the base of data of vertical CTD soundings in the Baltic Proper in 2004-2013. Permanently existing components (i.e., the components which are observed during the entire period of the presence of the CIL in the vertical thermo-haline structure of the sea) are: (i) quasi-homosaline sublayer, with water salinity typical for that in the upper mixed layer in winter period, and water temperature irregularly changing with depth; (ii) the underlying sublayer with increasing salinity and low temperature (the gradient sublayer); and (iii) the core of CIL (the minimum temperature), which is located close to the interface between these sublayers. It is argued that the homosaline sublayer is formed by local mechanisms - vertical wind-wave and convective mixing and advection from nearby shelves and neighbouring regions. Advection is supported by (i) long-lasting winds and (ii) horizontal convection due to differential warming / cooling of shallower regions. The gradient sublayer is formed by waters with T,S - parameters typical for that of the upper mixed layer of south-western sea basins (Barnholm and Arcons basins) at the beginning of spring warming-up period (March). It is suggested that the up-estuary propagation of these waters (with salinity about 7.5-8.5 psu) above the pycnocline is driven by the estuarine salinity gradient. This branch of circulation of intermediate waters is overlooked in classical estuarine circulation model of the Baltic Sea, however it is important for sea-scale transport of upper-layer contaminants, microplastics, organic matter etc. towards intermediate and deep sea layers. The investigations are supported by Russian Science Foundation via grant number 15-17-10020.

  18. Transport of magnetic flux and the vertical structure of accretion discs - II. Vertical profile of the diffusion coefficients

    NASA Astrophysics Data System (ADS)

    Guilet, Jérôme; Ogilvie, Gordon I.

    2013-04-01

    We investigate the radial transport of magnetic flux in a thin accretion disc, the turbulence being modelled by effective diffusion coefficients (viscosity and resistivity). Both turbulent diffusion and advection by the accretion flow contribute to flux transport, and they are likely to act in opposition. We study the consequences of the vertical variation of the diffusion coefficients, due to a varying strength of the turbulence. For this purpose, we consider three different vertical profiles of these coefficients. The first one is aimed at mimicking the turbulent stress profile observed in numerical simulations of magnetohydrodynamic turbulence in stratified discs. This enables us to confirm the robustness of the main result of Paper I obtained for uniform diffusion coefficients that, for weak magnetic fields, the contribution of the accretion flow to the transport velocity of magnetic flux is much larger than the transport velocity of mass. We then consider the presence of a dead zone around the equatorial plane where the physical resistivity is high while the turbulent viscosity is low. We find that it amplifies the previous effect: weak magnetic fields can be advected orders of magnitude faster than mass, for dead zones with a large vertical extension. The ratio of advection to diffusion, determining the maximum inclination of the field at the surface of the disc, is however not much affected. Finally, we study the effect of a non-turbulent layer at the surface of the disc, which has been suggested as a way to reduce the diffusion of the magnetic flux. We find that the reduction of the diffusion requires the conducting layer to extend below the height at which the magnetic pressure equals the thermal pressure. As a consequence, if the absence of turbulence is caused by the large-scale magnetic field, the highly conducting layer is inefficient at reducing the diffusion.

  19. Vertical Moist Thermodynamic Structure and Spatial-Temporal Evolution of the MJO in AIRS Observations

    NASA Technical Reports Server (NTRS)

    Tian, Baijun; Waliser, Duane E.; Fetzer, Eric J.; Lambrigtsen, Bjorn H.; Yung, Yuk L.; Wang, Bin

    2006-01-01

    The atmospheric moisture and temperature profiles from the Atmospheric Infrared Sounder (AIRS)/Advanced Microwave Sounding Unit on the NASA Aqua mission, in combination with the precipitation from the Tropical Rainfall Measuring Mission (TRMM), are employed to study the vertical moist thermodynamic structure and spatial-temporal evolution of the Madden-Julian oscillation (MJO). The AIRS data indicate that, in the Indian Ocean and western Pacific, the temperature anomaly exhibits a trimodal vertical structure: a warm (cold) anomaly in the free troposphere (800-250 hPa) and a cold (warm) anomaly near the tropopause (above 250 hPa) and in the lower troposphere (below 800 hPa) associated with enhanced (suppressed) convection. The AIRS moisture anomaly also shows markedly different vertical structures as a function of longitude and the strength of convection anomaly. Most significantly, the AIRS data demonstrate that, over the Indian Ocean and western Pacific, the enhanced (suppressed) convection is generally preceded in both time and space by a low-level warm and moist (cold and dry) anomaly and followed by a low-level cold and dry (warm and moist) anomaly. The MJO vertical moist thermodynamic structure from the AIRS data is in general agreement, particularly in the free troposphere, with previous studies based on global reanalysis and limited radiosonde data. However, major differences in the lower-troposphere moisture and temperature structure between the AIRS observations and the NCEP reanalysis are found over the Indian and Pacific Oceans, where there are very few conventional data to constrain the reanalysis. Specifically, the anomalous lower-troposphere temperature structure is much less well defined in NCEP than in AIRS for the western Pacific, and even has the opposite sign anomalies compared to AIRS relative to the wet/dry phase of the MJO in the Indian Ocean. Moreover, there are well-defined eastward-tilting variations of moisture with height in AIRS over the

  20. Heterogeneous OH Oxidation of Two Structure Isomers of Dimethylsuccinic Acid Aerosol: Reactivity and Oxidation Products

    NASA Astrophysics Data System (ADS)

    Chan, M. N.; Cheng, C. T.; Wilson, K. R.

    2014-12-01

    Organic aerosol contribute a significant mass fraction of ambient aerosol carbon and can continuously undergo oxidation by colliding with gas phase OH radicals. Although heterogeneous oxidation plays a significant role in the chemical transformation of organic aerosol, the effect of molecular structure on the reactivity and oxidation products remains unclear. We investigate the effect of branched methyl groups on the reactivity of two dimethylsuccinic acids (2,2-dimethylsuccinic acid (2,2-DMSA) and 2,3-dimethylsuccinic acid (2,3-DMSA)) toward gas phase OH radicals in an atmospheric pressure aerosol flow tube reactor. The oxidation products formed upon oxidation is characterized in real time by the Direct Analysis in Real Time (DART), an ambient soft ionization source. The 2,2-DMSA and 2,3-DMSA are structural isomers with the same oxidation state (OSC = -0.33) and carbon number (NC = 6), but different branching characteristics (2,2-DMSA has one secondary carbon and 2,3-DMSA has two tertiary carbons). The difference in molecular distribution of oxidation products observed in these two structural isomers would allow one to assess the sensitivity of kinetics and chemistry to the position of branched methyl group in the DMSA upon oxidation. We observe that the reactivity of 2,3-DMSA toward OH radicals is about 2 times faster than that of 2,2-DMSA. This difference in OH reactivity may attribute to the stability of the carbon-centered radical generated after hydrogen abstraction because an alkyl radical formed from the hydrogen abstraction on a tertiary carbon in 2,3-DMSA is more stable than on a secondary carbon in 2,2-DMSA. For both 2,2-DMSA and 2,3-DMSA, the molecular distribution and evolution of oxidation products is characterized by a predominance of functionalization products at the early oxidation stages. When the oxidation further proceeds, the fragmentation becomes more favorable and the oxidation mainly leads to the reduction of the carbon chain length through

  1. Toward predicting vertical detachment energies for superhalogen anions exclusively from 2-D structures

    NASA Astrophysics Data System (ADS)

    Sikorska, Celina

    2015-04-01

    In this work, the multiple linear regression (MLR) method was applied for quantitative structure-property relationship (QSPR) modeling and predicting vertical detachment energy of superhalogen anions with descriptors calculated from the molecular structure for the first time. The square of the correlation coefficient (R2 = 0.975), the cross-validated correlation coefficient (QCV2 = 0.859), and the square of correlation coefficients of the test set (QEXT2 = 0.960) demonstrated the reliability of the model. Since the developed QSPR model does not require 3-D structure generation and thus structure optimization with extensive quantum mechanical calculations it can be further used for relatively fast designing of new superhalogen anions.

  2. Aerosol analysis techniques and results from micro pulse lidar

    NASA Technical Reports Server (NTRS)

    Hlavka, Dennis L.; Spinhirne, James D.; Campbell, James R.; Reagan, John A.; Powell, Donna

    1998-01-01

    The effect of clouds and aerosol on the atmospheric energy balance is a key global change problem. Full knowledge of aerosol distributions is difficult to obtain by passive sensing alone. Aerosol and cloud retrievals in several important areas can be significantly improved with active remote sensing by lidar. Micro Pulse Lidar (MPL) is an aerosol and cloud profilometer that provides a detailed picture of the vertical structure of boundary layer and elevated dust or smoke plume aerosols. MPL is a compact, fully eyesafe, ground-based, zenith pointing instrument capable of full-time, long-term unattended operation at 523 nm. In October of 1993, MPL began taking full-time measurements for the Atmospheric Radiation Measurement (ARM) program at its Southern Great Plains (SGP) site and has since expanded to ARM sites in the Tropical West Pacific (TWP) and the North Slope of Alaska (NSA). Other MPL's are moving out to some of the 60 world-wide Aerosol Robotic Network (AERONET) sites which are already equipped with automatic sun-sky scanning spectral radiometers providing total column optical depth measurements. Twelve additional MPL's have been purchased by NASA to add to the aerosol and cloud database of the EOS ground validation network. The original MPL vertical resolution was 300 meters but the newer versions have a vertical resolution of 30 meters. These expanding data sets offer a significant new resource for atmospheric radiation analysis. Under the direction of Jim Spinhirne, the MPL analysis team at NASA/GSFC has developed instrument correction and backscatter analysis techniques for ARM to detect cloud boundaries and analyze vertical aerosol structures. A summary of MPL applications is found in Hlavka (1997). With the aid of independent total column optical depth instruments such as the Multifilter Rotating Shadowband Radiometer (MFRSR) at the ARM sites or sun photometers at the AERONET sites, the MPL data can be calibrated, and time-resolved vertical profiles of

  3. Analysis of the Molecules Structure and Vertical Electron Affinity of Organic Gas Impact on Electric Strength

    NASA Astrophysics Data System (ADS)

    Jiao, Juntao; Xiao, Dengming; Zhao, Xiaoling; Deng, Yunkun

    2016-05-01

    It is necessary to find an efficient selection method to pre-analyze the gas electric strength from the perspective of molecule structure and the properties for finding the alternative gases to sulphur hexafluoride (SF6). As the properties of gas are determined by the gas molecule structure, the research on the relationship between the gas molecule structure and the electric strength can contribute to the gas pre-screening and new gas development. In this paper, we calculated the vertical electron affinity, molecule orbits distribution and orbits energy of gas molecules by the means of density functional theory (DFT) for the typical structures of organic gases and compared their electric strengths. By this method, we find part of the key properties of the molecule which are related to the electric strength, including the vertical electron affinity, the lowest unoccupied molecule orbit (LUMO) energy, molecule orbits distribution and negative-ion system energy. We also listed some molecule groups such as unsaturated carbons double bonds (C=C) and carbonitrile bonds (C≡N) which have high electric strength theoretically by this method. supported by National Natural Science Foundation of China (Nos. 51177101 and 51337006)

  4. Tropospheric Vertical Profiles of Aerosol Optical, Microphysical and Concentration Properties in the Frame of the Hygra-CD Campaign (Athens, Greece 2014): A Case Study of Long-Range Transport of Mixed Aerosols

    NASA Astrophysics Data System (ADS)

    Papayannis, Alexandros; Argyrouli, Athina; Müller, Detlef; Tsaknakis, Georgios; Kokkalis, Panayotis; Binietoglou, Ioannis; Kazadzis, Stelios; Solomos, Stavros; Amiridis, Vassilis

    2016-06-01

    Combined multi-wavelength aerosol Raman lidar and sun photometry measurements were performed during the HYGRA-CD campaign over Athens, Greece during May-June 2014. The retrieved aerosol optical properties (3 aerosol backscatter at 355-532-1064 nm and 2 aerosol extinction profiles at 355-532 nm) were used as input to an inversion code to retrieve the aerosol microphysical properties (effective radius reff and number concentration N) using regularization techniques. Additionally, the volume concentration profile was derived for fine particles using the LIRIC code. In this paper we selected a complex case study of long-range transport of mixed aerosols (biomass burning particles mixed with dust) arriving over Athens between 10-12 June 2014 in the 1.5-4 km height. Between 2-3 km height we measured mean lidar ratios (LR) ranging from 45 to 58 sr (at 355 and 532 nm), while the Ångström exponent (AE) aerosol extinction-related values (355nm/532nm) ranged between 0.8-1.3. The retrieved values of reff and N ranged from 0.19±0.07 to 0.22±0.07 μm and 460±230 to 2200±2800 cm-3, respectively. The aerosol linear depolarization ratio (δ) at 532 nm was lower than 5-7% (except for the Saharan dust cases, where δ~10-15%).

  5. Retrievals of Extensive and Intensive Aerosol Parameters from Vertical Profiles of Extinction Coefficient Acquired by the MAESTRO Occultation Spectrometer: Case Study of Sarychev Volcano Plumes

    NASA Astrophysics Data System (ADS)

    Saha, A.; O'Neill, N. T.; McElroy, C. T.; Sioris, C.; Zou, J.

    2011-12-01

    The Canadian MAESTRO (Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation) instrument aboard the SCISAT-1 Satellite is an aerosol profiling occultation device that is part of the ACE (Atmospheric Chemistry Experiment) mission. This spectrometer produces spectra of aerosol extinction profiles above the upper troposphere. The extinction coefficient spectra permit the discrimination of sub-micron (fine mode) and super-micron (coarse mode) contributions and, in principle, the retrieval of fine mode effective radius. Retrievals applied to lower stratospheric and upper tropospheric aerosol plumes resulting from the eruption of the Sarychev-peak volcano in June of 2009 are presented. Preliminary results indicate that the fine and coarse mode discrimination and the particle sizing capability are coherent with available information on Sarychev aerosols.

  6. Structural design, layout analysis and routing strategy for constructing IC standard cells using emerging 3D vertical MOSFETs

    NASA Astrophysics Data System (ADS)

    Liu, Hongyi; Hong, Chuyang; Han, Ting; Zhou, Jun; Chen, Yijian

    2016-03-01

    As optical lithography and conventional transistor structure are approaching their physical limits, 3D vertical gate-all-around (GAA) nanowire MOSFETs and double-surrounding-gate (DSG) MOSFETs are two promising device candidates for post-FinFET logic scaling owing to their superior gate control and scaling potential. However, source, drain and gate of a vertical nanowire MOSFET and DSG MOSFETs are located in different physical layers. Consequently, structural design of IC devices/circuits, layout arrangement for high-density vertical nanowires/interconnects, and routing strategy are non-trivial challenges. In this paper, we shall discuss these critical issues for constructing standard cells using 3D vertical GAA nanowire MOSFETs and DSG MOSFETs. We redesigned the standard cells in Nangate Open Cell Library for 5nm node using vertical GAA nanowire MOSFETs and DSG MOSFETs. Experimental results verify the functionality of the proposed standard cell layout design approach.

  7. Aerosol Best Estimate Value-Added Product

    SciTech Connect

    Flynn, C; Turner, D; Koontz, A; Chand, D; Sivaraman, C

    2012-07-19

    The objective of the Aerosol Best Estimate (AEROSOLBE) value-added product (VAP) is to provide vertical profiles of aerosol extinction, single scatter albedo, asymmetry parameter, and Angstroem exponents for the atmospheric column above the Central Facility at the ARM Southern Great Plains (SGP) site. We expect that AEROSOLBE will provide nearly continuous estimates of aerosol optical properties under a range of conditions (clear, broken clouds, overcast clouds, etc.). The primary requirement of this VAP was to provide an aerosol data set as continuous as possible in both time and height for the Broadband Heating Rate Profile (BBHRP) VAP in order to provide a structure for the comprehensive assessment of our ability to model atmospheric radiative transfer for all conditions. Even though BBHRP has been completed, AEROSOLBE results are very valuable for environmental, atmospheric, and climate research.

  8. Abnormal Vertical Structure of Water Vapor over Taklamakan Desert from COSMIC Observations

    NASA Astrophysics Data System (ADS)

    Wang, J. K.; Liu, X. Y.; Yin, H. T.

    2012-04-01

    Water vapor is an important greenhouse gas. The vertical structure of the water vapor has a great impact on the weather and the climate. The Taklamakan desert is the largest desert in China, surrounded by a series of high mountains. The vertical structures of the water vapor over the Taklamakan desert have rarely been described by former research, due to the lack of conventional observations. This work is the first result of the water vapor vertical structure over the Taklamakan desert and its surroundings (35N-47N, 75E-94E) from the COSMIC occultation observations. Analysis found that a humid layer frequently occurs at the average height of 4800m. An "abnormal profile" was defined if a peak was observed in mid-troposphere in the humidity profile. This "abnormal profile" appeared in 24% of the total profile and appeared much more often inside the desert than outside during the year 2008 to 2010. Based on model analysis, two possible mechanisms were proposed to explain the reason of the formation of the abnormal profile. Through the statistics, 53% of total "abnormal profiles" were due to the transported water vapor topographic uplift effect, the topography of the desert forces the east-blowing wind to climb the surrounding mountains, bringing the low-altitude water vapor to mid-troposphere above the desert. The rest were due to the lack of water content in the air close to the ground. This new discovery and its possible explanations will help us to understand more about the climate of the Taklamakan desert and possibly also other similar regions.

  9. Method and apparatus for drilling horizontal holes in geological structures from a vertical bore

    DOEpatents

    Summers, David A.; Barker, Clark R.; Keith, H. Dean

    1982-01-01

    This invention is directed to a method and apparatus for drilling horizontal holes in geological strata from a vertical position. The geological structures intended to be penetrated in this fashion are coal seams, as for in situ gasification or methane drainage, or in oil-bearing strata for increasing the flow rate from a pre-existing well. Other possible uses for this device might be for use in the leaching of uranium ore from underground deposits or for introducing horizontal channels for water and steam injections.

  10. Quantifying forest vertical structure to determine bird habitat quality in the Greenbelt Corridor, Denton, TX

    NASA Astrophysics Data System (ADS)

    Matsubayashi, Shiho

    This study presents the integration of light detection and range (LiDAR) and hyperspectral remote sensing to create a three-dimensional bird habitat map in the Greenbelt Corridor of the Elm Fork of the Trinity River. This map permits to examine the relationship between forest stand structure, landscape heterogeneity, and bird community composition. A biannual bird census was conducted at this site during the breeding seasons of 2009 and 2010. Census data combined with the three-dimensional map suggest that local breeding bird abundance, community structure, and spatial distribution patterns are highly influenced by vertical heterogeneity of vegetation surface. For local breeding birds, vertical heterogeneity of canopy surface within stands, connectivity to adjacent forest patches, largest forest patch index, and habitat (vegetation) types proved to be the most influential factors to determine bird community assemblages. Results also highlight the critical role of secondary forests to increase functional connectivity of forest patches. Overall, three-dimensional habitat descriptions derived from integrated LiDAR and hyperspectral data serve as a powerful bird conservation tool that shows how the distribution of bird species relates to forest composition and structure at various scales.

  11. Analysis of Tropical Forest Vertical and Spatial Structural Dynamics Using Large-footprint Lidar

    NASA Astrophysics Data System (ADS)

    Sheldon, S. L.; Dubayah, R. O.; Clark, D. B.; Hofton, M. A.; Blair, J.

    2006-12-01

    In this paper we examine the ability of an airborne lidar, the Laser Vegetation Imaging Sensor (LVIS) to determine changes in the vertical structure of a tropical wet forest. LVIS, a large-footprint scanning lidar, collected data over La Selva Biological Station in Costa Rica, in March of 1998 and March of 2005. The La Selva region contains significant landscapes of old-growth and secondary forests, as well as other vegetation and management types. The specific objective of this study is to analyze the changes in vertical canopy structure and dynamics in secondary forest sites as compared to old-growth forests utilizing waveforms and waveform-derived metrics. Nearly co-incident footprints between years were used to assess structural changes at various spatial scales ranging from individual footprints to landscape level. On average, secondary forests showed significant growth as a function of age/height at all spatial scales. In contrast, old-growth forests were characterized by largely stable lidar heights. At the local (footprint) scale, considerable variability in growth rates for secondary forests, as well as in growth-loss in old-growth areas was observed. The number of footprints with large growth-loss (> 5 m), presumably caused by tree mortality in the old-growth forests, was consistent with expected mortality rates over a 7 year period.

  12. The structural evolution of magnesium acetate complex in aerosols by FTIR-ATR spectra

    NASA Astrophysics Data System (ADS)

    Pang, Shu-Feng; Wu, Chang-Qin; Zhang, Qing-Nuan; Zhang, Yun-Hong

    2015-05-01

    The structural evolution of magnesium acetate complex in aerosols with the relative humidity (RH) has been studied by ATR-FTIR technique. When the RH is higher than 66%, the ν4 band lies at 929 cm-1 meaning the free CH3COO- ions in Mg(CH3COO)2 droplets. At the 66% RH, ν4 band positioned at 939 cm-1, accompanying the ν8 band shift to 1554 cm-1, which indicats that the free CH3COO- ions are bounded to Mg2+ ions to form [Mg(H2O)5(CH3COO)]+ species. At the 57.7% RH, the ν8-COO band shifts to 1556 cm-1 accompanying the ν3 band at 1421 cm-1 and the appearance of shoulder at 1452 cm-1, which suggests the formation of chain-structure connected by the bridging bidentate of Mg2(CH3COO)4(H2O)2. In the region of 57.7-18.7% RH, the shoulder at 1452 cm-1 increases with the decrease in RH, showing the increase of Mg2(CH3COO)4(H2O)2. From the water-content, the water-transfer from and to the surface of the aerosols became limited, showing the aerosols enter the gel state. Below 18.7%RH, water-loss becomes rapid and the ν8 band performs blue-shift. At 3.8%RH, the ν8 band positioned at 1581 cm-1, showing the anhydrous Mg(CH3COO)2 solid, which can be reflected by the ν4 band at 947 cm-1. During the humidification process, the reverse structural evolution can be found.

  13. Vertical Profiles of Light Scattering, Light Absorption, and Single Scattering Albedo during the Dry, Biomass Burning Season in Southern Africa and Comparisons of In Situ and Remote Sensing Measurements of Aerosol Optical Depths

    NASA Technical Reports Server (NTRS)

    Magi, Brian I.; Hobbs, Peter V.; Schmid, Beat; Redermann, Jens

    2003-01-01

    Airborne in situ measurements of vertical profiles of aerosol light scattering, light absorption, and single scattering albedo (omega (sub 0)) are presented for a number of locations in southern Africa during the dry, biomass burning season. Features of the profiles include haze layers, clean air slots, and marked decreases in light scattering in passing from the boundary layer into the free troposphere. Frequency distributions of omega (sub 0) reflect the strong influence of smoke from biomass burning. For example, during a period when heavy smoke was advected into the region from the north, the mean value of omega (sub 0) in the boundary layer was 0.81 +/- 0.02 compared to 0.89 +/- 0.03 prior to this intrusion. Comparisons of layer aerosol optical depths derived from the in situ measurements with those measured by a Sun photometer aboard the aircraft show excellent agreement.

  14. Cloud vertical structure, radiative heating profile and diurnal variation during TOGA COARE

    NASA Astrophysics Data System (ADS)

    Qian, Taotao

    This thesis consists of two parts: (1) the vertical structure of clouds and radiative heating during TOGA COARE and (2) diurnal variations during TOGA COARE. The purpose of the first part (Chapter 1) is to determine a realistic gridded (1 degree by 1 degree) cloud vertical structure and radiative heating profile for the Intensive Flux Array (IFA) during the Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean Atmosphere Response Experiment (COARE). First, we deduce the cloud vertical structure from the sounding data using an improved relative humidity (RH) threshold method. The RH threshold is height-dependent and is tuned by three surface and TOA observations of clouds: the Micropulse Lidar (MPL), the High-Resolution Infrared Sounder (HIRS) and the International Satellite Cloud Climatology Project (ISCCP). Then, a modified CCM3 Column Radiation Model (CRM) is used to calculate the radiative heating profiles. The modification of the CRM replaces the model microphysics with the observed microphysics profiles. The calculated radiation budgets are shown to be consistent with the surface and top of the atmosphere (TOA) observations and are much better than those of the standard version of the CRM. The purpose of the second part (Chapter 2) is to test different diurnal variation mechanisms, that have been proposed in previous studies, by using the abundant observational data obtained during TOGA COARE. The preliminary findings are: (1) The stratiform precipitation lags the convective precipitation, suggesting that the effect of the life cycle of the mesoscale convective systems (MCS) is important to the midnight rainfall maximum; i.e., the stratiform component helps to shift the maximum toward midnight. This supports the MCS life cycle mechanism. (2) This study supports the direct radiation-convection interaction mechanism and emphasize that the variation is strongly affected by the variation of upper-level clouds. (3) The current study does not, however, support the

  15. Vertical structure of cross-shore currents from wind-induced setup

    USGS Publications Warehouse

    Gelfenbaum, Guy

    1991-01-01

    Most of the storm surge models presented in the literature are vertically averaged and calculate only the sea-surface elevation and mean flow. Whereas these models may be adequate for predicting storm surge heights for flooding purposes, they neglect the vertical structure of the flow and the boundary shear stress, which are both critical for predicting cross-shore sediment transport. The steady and horizontally uniform equations of motion are used here to compute the sea-surface slope, the vertical structure of the cross-shore currents, and the boundary shear stress in a shallow wind dominated environment. The steady state model developed here balances the pressure gradient and the stress divergence, resulting in sea-surface slope and associated pressure gradient in the opposite direction of the wind, thus inducing a reversal in the currents near the bed. The Reynolds stress is modeled with a depth-dependent turbulent diffusion coefficient so that both the boundary shear stress and the velocity field are calculated, avoiding the need to set a bottom drag coefficient. Input parameters for this model are simply the wind stress, the water depth, and z0, the bed roughness parameter. A sensitivity test of the model results to various values of z0 indicates that large changes in z0 cause only minor differences in the surface slope, and moderate differences in the velocity field and boundary shear stress. Given the sediment size distribution and the small scale morphology of the bed, a reasonable estimate of z0 may be obtained and the above uncertainty will be nearly eliminated.

  16. Thermal Emission Spectrometer Results: Mars Atmospheric Thermal Structure and Aerosol Distribution

    NASA Technical Reports Server (NTRS)

    Smith, Michael D.; Pearl, John C.; Conrath, Barney J.; Christensen, Philip R.; Vondrak, Richard R. (Technical Monitor)

    2001-01-01

    Infrared spectra returned by the Thermal Emission Spectrometer (TES) are well suited for retrieval of the thermal structure and the distribution of aerosols in the Martian atmosphere. Combined nadir- and limb-viewing spectra allow global monitoring of the atmosphere up to 0.01 mbar (65 km). We report here on the atmospheric thermal structure and the distribution of aerosols as observed thus far during the mapping phase of the Mars Global Surveyor mission. Zonal and temporal mean cross sections are used to examine the seasonal evolution of atmospheric temperatures and zonal winds during a period extending from northern hemisphere mid-summer through vernal equinox (L(sub s) = 104-360 deg). Temperature maps at selected pressure levels provide a characterization of planetary-scale waves. Retrieved atmospheric infrared dust opacity maps show the formation and evolution of regional dust storms during southern hemisphere summer. Response of the atmospheric thermal structure to the changing dust loading is observed. Maps of water-ice clouds as viewed in the thermal infrared are presented along with seasonal trends of infrared water-ice opacity. Uses of these observations for diagnostic studies of the dynamics of the atmosphere are discussed.

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

    SciTech Connect

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

    2011-07-06

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

  18. Vertical stratification of ichneumonid wasp communities: the effects of forest structure and life-history traits.

    PubMed

    Di Giovanni, Filippo; Cerretti, Pierfilippo; Mason, Franco; Minari, Emma; Marini, Lorenzo

    2015-10-01

    Parasitoid wasp communities of the canopy of temperate forests are still largely unexplored. Very little is known about the community composition of parasitoids between canopy and understory and how much of this difference is related to forest structure or parasitoid biological strategies. In this study we investigated upon the difference in the community composition of the parasitic wasps Ichneumonidae between canopy and understory in a lowland temperate forest in northern Italy. We used general linear models to test whether parasitic strategy modifies species vertical stratification and the effect of forest structure. We also tested differences in β-diversity between canopy and understory traps and over time within single forest layers. We found that stand basal area was positively related to species richness, suggesting that the presence of mature trees can influence local wasp diversity, providing a higher number of microhabitats and hosts. The ichneumonid community of the canopy was different from that of the understory, and the β-diversity analysis showed higher values for the canopy, due to a higher degree of species turnover between traps. In our analyses, the vertical stratification was different between groups of ichneumonids sharing different parasitic strategies. Idiobiont parasitoids of weakly or deeply concealed hosts were more diverse in the understory than in the canopy while parasitoids of spiders were equally distributed between the two layers. Even though the ichneumonid community was not particularly species-rich in the canopy of the temperate forests, the extension of sampling to that habitat significantly increased the number of species recorded.

  19. A numerical investigation of the wake structure of vertical axis wind turbines

    NASA Astrophysics Data System (ADS)

    Balaras, Elias; Posa, Antonio; Leftwich, Megan

    2014-11-01

    Recent field-testing has shown that vertical axis wind turbines (VAWT) in wind farm configurations have the potential to reach higher power densities, when compared to the more widespread horizontal axis turbines. A critical component in achieving this goal is a good understanding of the wake structure and how it is influenced by operating conditions. In the present study the Large-Eddy Simulation technique is adopted to characterize the wake of a small vertical axis wind turbine and to explore its dependence on the value of its Tip Speed Ratio (TSR). It will be shown that its wake significantly differs from that of a spinning cylinder, often adopted to model this typology of machines: the displacement of the momentum deficit towards the windward side follows the same behavior, but turbulence is higher on the leeward side. An initial increase of the momentum deficit is observed moving downstream, with central peaks in the core of the near wake for both momentum and turbulent kinetic energy, especially at lower TSRs. No back-flow is produced downstream of the turbine. The interaction between blades is stronger at higher values of the TSR, while the production of coherent structures is enhanced at lower TSRs, with large rollers populating the leeward side of the wake.

  20. RADIATION PRESSURE-SUPPORTED ACCRETION DISKS: VERTICAL STRUCTURE, ENERGY ADVECTION, AND CONVECTIVE STABILITY

    SciTech Connect

    Gu Weimin

    2012-07-10

    By taking into account the local energy balance per unit volume between the viscous heating and the advective cooling plus the radiative cooling, we investigate the vertical structure of radiation pressure-supported accretion disks in spherical coordinates. Our solutions show that the photosphere of the disk is close to the polar axis and therefore the disk seems to be extremely thick. However, the density profile implies that most of the accreted matter exists in a moderate range around the equatorial plane. We show that the well-known polytropic relation between the pressure and the density is unsuitable for describing the vertical structure of radiation pressure-supported disks. More importantly, we find that the energy advection is significant even for slightly sub-Eddington accretion disks. We argue that the non-negligible advection may help us understand why the standard thin disk model is likely to be inaccurate above {approx}0.3 Eddington luminosity, which was found by some works on black hole spin measurement. Furthermore, the solutions satisfy the Solberg-Hoiland conditions, which indicate the disk to be convectively stable. In addition, we discuss the possible link between our disk model and ultraluminous X-ray sources.

  1. Modal structure of chemical mass size distribution in the high Arctic aerosol

    NASA Astrophysics Data System (ADS)

    Hillamo, Risto; Kerminen, Veli-Matti; Aurela, Minna; MäKelä, Timo; Maenhaut, Willy; Leek, Caroline

    2001-11-01

    Chemical mass size distributions of aerosol particles were measured in the remote marine boundary layer over the central Arctic Ocean as part of the Atmospheric Research Program on the Arctic Ocean Expedition 1996 (AOE-96). An inertial impaction method was used to classify aerosol particles into different size classes for subsequent chemical analysis. The particle chemical composition was determined by ion chromatography and by the particle-induced X-ray emission technique. Continuous particle size spectra were extracted from the raw data using a data inversion method. Clear and varying modal structures for aerosols consisting of primary sea-salt particles or of secondary particles related to dimethyl sulfide emissions were found. Concentration levels of all modes decreased rapidly when the distance from open sea increased. In the submicrometer size range the major ions found by ion chromatography were sulfate, methane sulfonate, and ammonium. They had most of the time a clear Aitken mode and one or two accumulation modes, with aerodynamic mass median diameters around 0.1 μm, 0.3 μm, and between 0.5-1.0 μm, respectively. The overall submicron size distributions of these three ions were quite similar, suggesting that they were internally mixed over most of this size range. The corresponding modal structure was consistent with the mass size distributions derived from the particle number size distributions measured with a differential mobility particle sizer. The Aitken to accumulation mode mass ratio for nss-sulfate and MSA was substantially higher during clear skies than during cloudy periods. Primary sea-salt particles formed a mode with an aerodynamic mass median diameter around 2 μm. In general, the resulting continuous mass size distributions displayed a clear modal structure consistent with our understanding of the two known major source mechanisms. One is the sea-salt aerosol emerging from seawater by bubble bursting. The other is related to

  2. Impacts of feeding strategy on microbial community structure diversity in vertical flow constructed wetlands

    NASA Astrophysics Data System (ADS)

    Jia, W. L.; Zhang, J.; Wang, Q.

    2016-08-01

    The impacts of feeding strategy (intermittently or continuously) on contaminant removal performance and microbial community structure in vertical flow constructed wetlands (VFCWs) were evaluated. The results showed that intermittent feeding strategy improved the removal of COD, TP and ammonium in VFCWs, although TN removal was weakened correspondingly The bacterial diversity decreased with the increase of substratum depth in all CWs. The intermittent feeding favored the growth of microorganisms due to the enhancement of oxygen content in the substratum. The feeding strategy had little impact on the microbial community in the surface substratum. However, in the bottom substratum, the impacts were of great significance. The microbial community structure similarity between the CWs with different feeding strategies was low.

  3. Estimates of the Tropospheric Vertical Structure of Neptune Based on Microwave Radiative Transfer Studies

    NASA Technical Reports Server (NTRS)

    DeBoer, David R.; Steffes, Paul G.

    1996-01-01

    A radiative transfer model incorporating, among other things, the recently measured centimeter wavelength opacity of H2S, the full line catalog of PH3, and absorption due to CO has been developed to study the tropospheric vertical structure of Neptune. To match radio-telescope observations, subsolar amounts of NH3 and supersolar amounts of H2S are found to be needed, as has been previously noted. To match both the measured microwave emission and the measured opacity at 13 cm and 6.3 bars by Voyager 2, an H2S dominant atmosphere (H2S/NH3 approximately equals 40) with enhanced PH3 (15 x solar) or NH3 supersaturation with respect to the putative NH4SH cloud (400 ppbv) seems to be indicated. Due to the possible importance of PH3 opacity, it is suggested that measurements of its opacity could aid in resolving some of the outstanding ambiguities concerning Neptune's tropospheric structure.

  4. Advanced Fluid--Structure Interaction Techniques in Application to Horizontal and Vertical Axis Wind Turbines

    NASA Astrophysics Data System (ADS)

    Korobenko, Artem

    During the last several decades engineers and scientists put significant effort into developing reliable and efficient wind turbines. As a wind power production demands grow, the wind energy research and development need to be enhanced with high-precision methods and tools. These include time-dependent, full-scale, complex-geometry advanced computational simulations at large-scale. Those, computational analysis of wind turbines, including fluid-structure interaction simulations (FSI) at full scale is important for accurate and reliable modeling, as well as blade failure prediction and design optimization. In current dissertation the FSI framework is applied to most challenging class of problems, such as large scale horizontal axis wind turbines and vertical axis wind turbines. The governing equations for aerodynamics and structural mechanics together with coupled formulation are explained in details. The simulations are performed for different wind turbine designs, operational conditions and validated against field-test and wind tunnel experimental data.

  5. Sensitivity of top-down CO source estimates to the modeled vertical structure in atmospheric CO

    NASA Astrophysics Data System (ADS)

    Jiang, Z.; Jones, D. B. A.; Worden, H. M.; Henze, D. K.

    2015-02-01

    We assessed the sensitivity of regional CO source estimates to the modeled vertical CO distribution by assimilating multi-spectral MOPITT (Measurements of Pollution In The Troposphere) V5J CO retrievals with the GEOS-Chem model. We compared the source estimates obtained by assimilating the CO profiles and the surface layer retrievals from June 2004 to May 2005. Because the surface layer retrievals are less sensitive to CO in the free troposphere, it is expected that they should provide constraints in the CO source estimates that are less sensitive to the vertical structure of CO in the free troposphere. The inferred source estimates all suggest a reduction in CO emissions in the tropics and subtropics, and an increase in the extratropics over the a priori estimates. The tropical decreases were particularly pronounced for regions where the biogenic source of CO was dominant, suggesting an overestimate of the a priori isoprene source of CO in the model. We found that the differences between the regional source estimates inferred from the profile and surface layer retrievals for 2004-2005 were small, generally less than 10% for the main continental regions, except for estimates for southern Asia, North America, and Europe. Because of discrepancies in convective transport in the model, the CO source estimates for India and southeastern Asia inferred from the CO profiles were significantly higher than those estimated from the surface layer retrievals during June-August 2004. On the other hand, the profile inversion underestimated the CO emissions from North America and Europe compared to the assimilation of the surface layer retrievals. We showed that vertical transport of air from the North American and European boundary layers is slower than from other continental regions, and thus air in the free troposphere from North America and Europe in the model is more chemically aged, which could explain the discrepancy between the source estimates inferred from the profile

  6. The vertical structure of cloud radiative heating over the Indian subcontinent during summer monsoon

    NASA Astrophysics Data System (ADS)

    Johansson, E.; Devasthale, A.; L'Ecuyer, T.; Ekman, A. M. L.; Tjernström, M.

    2015-02-01

    Every year the monsoonal circulation over the Indian subcontinent gives rise to a variety of cloud types that differ considerably in their ability to heat or cool the atmosphere. These clouds in turn affect monsoon dynamics via their radiative impacts, both at the surface and in the atmosphere. New generation of satellites carrying active radar and lidar sensors are allowing realistic quantification of cloud radiative heating (CRH) by resolving the vertical structure of the atmosphere in an unprecedented detail. Obtaining this information is a first step in closing the knowledge gap in our understanding of the role that different clouds play as regulators of the monsoon and vice versa. Here, we use collocated CloudSat-CALIPSO data sets to understand following aspects of cloud-radiation interactions associated with Indian monsoon circulation. (1) How does the vertical distribution of CRH evolve over the Indian continent throughout monsoon season? (2) What is the absolute contribution of different clouds types to the total CRH? (3) How do active and break periods of monsoon affect the distribution of CRH? And finally, (4) what are the net radiative effects of different cloud types on surface heating? In general, the vertical structure of CRH follows the northward migration and the retreat of monsoon from May to October. It is found that the alto- and nimbostratus clouds intensely warm the middle troposphere and equally strongly cool the upper troposphere. Their warming/cooling consistently exceeds ±0.2 K day-1 (after weighing by vertical cloud fraction) in monthly mean composites throughout the middle and upper troposphere respectively, with largest impact observed in June, July and August. Deep convective towers cause considerable warming in the middle and upper troposphere, but strongly cool the base and inside of the tropical tropopause layer (TTL). Such cooling is stronger during active (-1.23 K day-1) monsoon conditions compared to break periods (-0.36 K day-1

  7. Vertically aligned P(VDF-TrFE) core-shell structures on flexible pillar arrays

    PubMed Central

    Choi, Yoon-Young; Yun, Tae Gwang; Qaiser, Nadeem; Paik, Haemin; Roh, Hee Seok; Hong, Jongin; Hong, Seungbum; Han, Seung Min; No, Kwangsoo

    2015-01-01

    PVDF and P(VDF-TrFE) nano- and micro- structures have been widely used due to their potential applications in several fields, including sensors, actuators, vital sign transducers, and energy harvesters. In this study, we developed vertically aligned P(VDF-TrFE) core-shell structures using high modulus polyurethane acrylate (PUA) pillars as the support structure to maintain the structural integrity. In addition, we were able to improve the piezoelectric effect by 1.85 times from 40 ± 2 to 74 ± 2 pm/V when compared to the thin film counterpart, which contributes to the more efficient current generation under a given stress, by making an effective use of the P(VDF-TrFE) thin top layer as well as the side walls. We attribute the enhancement of piezoelectric effects to the contributions from the shell component and the strain confinement effect, which was supported by our modeling results. We envision that these organic-based P(VDF-TrFE) core-shell structures will be used widely as 3D sensors and power generators because they are optimized for current generations by utilizing all surface areas, including the side walls of core-shell structures. PMID:26040539

  8. Vertically aligned P(VDF-TrFE) core-shell structures on flexible pillar arrays

    SciTech Connect

    Choi, Yoon-Young; Yun, Tae Gwang; Qaiser, Nadeem; Paik, Haemin; Roh, Hee Seok; Hong, Jongin; Hong, Seungbum; Han, Seung Min; No, Kwangsoo

    2015-06-04

    PVDF and P(VDF-TrFE) nano- and micro- structures are widely used due to their potential applications in several fields, including sensors, actuators, vital sign transducers, and energy harvesters. In this study, we developed vertically aligned P(VDF-TrFE) core-shell structures using high modulus polyurethane acrylate (PUA) pillars as the support structure to maintain the structural integrity. In addition, we were able to improve the piezoelectric effect by 1.85 times from 40 ± 2 to 74 ± 2 pm/V when compared to the thin film counterpart, which contributes to the more efficient current generation under a given stress, by making an effective use of the P(VDF-TrFE) thin top layer as well as the side walls. We attribute the enhancement of piezoelectric effects to the contributions from the shell component and the strain confinement effect, which was supported by our modeling results. We envision that these organic-based P(VDF-TrFE) core-shell structures will be used widely as 3D sensors and power generators because they are optimized for current generations by utilizing all surface areas, including the side walls of core-shell structures.

  9. Vertically aligned P(VDF-TrFE) core-shell structures on flexible pillar arrays

    DOE PAGES

    Choi, Yoon-Young; Yun, Tae Gwang; Qaiser, Nadeem; Paik, Haemin; Roh, Hee Seok; Hong, Jongin; Hong, Seungbum; Han, Seung Min; No, Kwangsoo

    2015-06-04

    PVDF and P(VDF-TrFE) nano- and micro- structures are widely used due to their potential applications in several fields, including sensors, actuators, vital sign transducers, and energy harvesters. In this study, we developed vertically aligned P(VDF-TrFE) core-shell structures using high modulus polyurethane acrylate (PUA) pillars as the support structure to maintain the structural integrity. In addition, we were able to improve the piezoelectric effect by 1.85 times from 40 ± 2 to 74 ± 2 pm/V when compared to the thin film counterpart, which contributes to the more efficient current generation under a given stress, by making an effective use ofmore » the P(VDF-TrFE) thin top layer as well as the side walls. We attribute the enhancement of piezoelectric effects to the contributions from the shell component and the strain confinement effect, which was supported by our modeling results. We envision that these organic-based P(VDF-TrFE) core-shell structures will be used widely as 3D sensors and power generators because they are optimized for current generations by utilizing all surface areas, including the side walls of core-shell structures.« less

  10. Vertically aligned P(VDF-TrFE) core-shell structures on flexible pillar arrays.

    PubMed

    Choi, Yoon-Young; Yun, Tae Gwang; Qaiser, Nadeem; Paik, Haemin; Roh, Hee Seok; Hong, Jongin; Hong, Seungbum; Han, Seung Min; No, Kwangsoo

    2015-01-01

    PVDF and P(VDF-TrFE) nano- and micro- structures have been widely used due to their potential applications in several fields, including sensors, actuators, vital sign transducers, and energy harvesters. In this study, we developed vertically aligned P(VDF-TrFE) core-shell structures using high modulus polyurethane acrylate (PUA) pillars as the support structure to maintain the structural integrity. In addition, we were able to improve the piezoelectric effect by 1.85 times from 40 ± 2 to 74 ± 2 pm/V when compared to the thin film counterpart, which contributes to the more efficient current generation under a given stress, by making an effective use of the P(VDF-TrFE) thin top layer as well as the side walls. We attribute the enhancement of piezoelectric effects to the contributions from the shell component and the strain confinement effect, which was supported by our modeling results. We envision that these organic-based P(VDF-TrFE) core-shell structures will be used widely as 3D sensors and power generators because they are optimized for current generations by utilizing all surface areas, including the side walls of core-shell structures. PMID:26040539

  11. Assessment of aerosol optical property and radiative effect for the layer decoupling cases over the northern South China Sea during the 7-SEAS/Dongsha Experiment

    NASA Astrophysics Data System (ADS)

    Pani, Shantanu Kumar; Wang, Sheng-Hsiang; Lin, Neng-Huei; Tsay, Si-Chee; Lolli, Simone; Chuang, Ming-Tung; Lee, Chung-Te; Chantara, Somporn; Yu, Jin-Yi

    2016-05-01

    The aerosol radiative effect can be modulated by the vertical distribution and optical properties of aerosols, particularly when aerosol layers are decoupled. Direct aerosol radiative effects over the northern South China Sea (SCS) were assessed by incorporating an observed data set of aerosol optical properties obtained from the Seven South East Asian Studies (7-SEAS)/Dongsha Experiment into a radiative transfer model. Aerosol optical properties for a two-layer structure of aerosol transport were estimated. In the radiative transfer calculations, aerosol variability (i.e., diversity of source region, aerosol type, and vertical distribution) for the complex aerosol environment was also carefully quantified. The column-integrated aerosol optical depth (AOD) at 500 nm was 0.1-0.3 for near-surface aerosols and increased 1-5 times in presence of upper layer biomass-burning aerosols. A case study showed the strong aerosol absorption (single-scattering albedo (ω) ≈ 0.92 at 440 nm wavelength) exhibited by the upper layer when associated with predominantly biomass-burning aerosols, and the ω (≈0.95) of near-surface aerosols was greater than that of the upper layer aerosols because of the presence of mixed type aerosols. The presence of upper level aerosol transport could enhance the radiative efficiency at the surface (i.e., cooling) and lower atmosphere (i.e., heating) by up to -13.7 and +9.6 W m-2 per AOD, respectively. Such enhancement could potentially modify atmospheric stability, can influence atmospheric circulation, as well as the hydrological cycle over the tropical and low-latitude marginal northern SCS.

  12. Estimating Forest Vertical Structure from Multialtitude, Fixed-Baseline Radar Interferometric and Polarimetric Data

    NASA Technical Reports Server (NTRS)

    Treuhaft, Robert N.; Law, Beverly E.; Siqueira, Paul R.

    2000-01-01

    Parameters describing the vertical structure of forests, for example tree height, height-to-base-of-live-crown, underlying topography, and leaf area density, bear on land-surface, biogeochemical, and climate modeling efforts. Single, fixed-baseline interferometric synthetic aperture radar (INSAR) normalized cross-correlations constitute two observations from which to estimate forest vertical structure parameters: Cross-correlation amplitude and phase. Multialtitude INSAR observations increase the effective number of baselines potentially enabling the estimation of a larger set of vertical-structure parameters. Polarimetry and polarimetric interferometry can further extend the observation set. This paper describes the first acquisition of multialtitude INSAR for the purpose of estimating the parameters describing a vegetated land surface. These data were collected over ponderosa pine in central Oregon near longitude and latitude -121 37 25 and 44 29 56. The JPL interferometric TOPSAR system was flown at the standard 8-km altitude, and also at 4-km and 2-km altitudes, in a race track. A reference line including the above coordinates was maintained at 35 deg for both the north-east heading and the return southwest heading, at all altitudes. In addition to the three altitudes for interferometry, one line was flown with full zero-baseline polarimetry at the 8-km altitude. A preliminary analysis of part of the data collected suggests that they are consistent with one of two physical models describing the vegetation: 1) a single-layer, randomly oriented forest volume with a very strong ground return or 2) a multilayered randomly oriented volume; a homogeneous, single-layer model with no ground return cannot account for the multialtitude correlation amplitudes. Below the inconsistency of the data with a single-layer model is followed by analysis scenarios which include either the ground or a layered structure. The ground returns suggested by this preliminary analysis seem

  13. Investigation of the aerosol structure over an urban area using a polarization lidar.

    PubMed

    Kolev, Nikolay; Tatarov, Boyan; Kaprielov, Boiko; Kolev, Ivan

    2004-10-01

    The paper presents a lidar study of the aerosol structure in the planetary boundary layer in the case of radiation fog and haze. A conceptual model of the dynamics of the depolarization coefficient profile during the mixing layer development, taking into account the presence of a multilayered inversions and radiation fogs, is proposed. Various techniques are employed in the processing of the lidar signal in order to determine the mixing layer height as well as more details of the aerosol structure in the low atmosphere, namely, finding the maximum of the signal returned from the lowest temperature inversion, the crossing point of the S function's first derivative with the x axis, and profiles of the depolarization ratio. After the complete destruction of the stable stratification, a low constant value of the depolarization ratio within the newly formed mixing layer is being observed. The study of stable boundary layer disintegration and convective boundary layer formation in the presence of fogs and/or clouds is of both scientific and practical significance in what concerns the protection of the environment and the aviation meteorology.

  14. The vertical structure of upper ocean variability at the Porcupine Abyssal Plain during 2012-2013

    NASA Astrophysics Data System (ADS)

    Damerell, Gillian M.; Heywood, Karen J.; Thompson, Andrew F.; Binetti, Umberto; Kaiser, Jan

    2016-05-01

    This study presents the characterization of variability in temperature, salinity and oxygen concentration, including the vertical structure of the variability, in the upper 1000 m of the ocean over a full year in the northeast Atlantic. Continuously profiling ocean gliders with vertical resolution between 0.5 and 1 m provide more information on temporal variability throughout the water column than time series from moorings with sensors at a limited number of fixed depths. The heat, salt and dissolved oxygen content are quantified at each depth. While the near surface heat content is consistent with the net surface heat flux, heat content of the deeper layers is driven by gyre-scale water mass changes. Below ˜150m, heat and salt content display intraseasonal variability which has not been resolved by previous studies. A mode-1 baroclinic internal tide is detected as a peak in the power spectra of water mass properties. The depth of minimum variability is at ˜415m for both temperature and salinity, but this is a depth of high variability for oxygen concentration. The deep variability is dominated by the intermittent appearance of Mediterranean Water, which shows evidence of filamentation. Susceptibility to salt fingering occurs throughout much of the water column for much of the year. Between about 700-900 m, the water column is susceptible to diffusive layering, particularly when Mediterranean Water is present. This unique ability to resolve both high vertical and temporal variability highlights the importance of intraseasonal variability in upper ocean heat and salt content, variations that may be aliased by traditional observing techniques.

  15. Turbulence vertical structure of the boundary layer during the afternoon transition

    NASA Astrophysics Data System (ADS)

    Darbieu, C.; Lohou, F.; Lothon, M.; Vilà-Guerau de Arellano, J.; Couvreux, F.; Durand, P.; Pino, D.; Patton, E. G.; Nilsson, E.; Blay-Carreras, E.; Gioli, B.

    2015-09-01

    We investigate the decay of planetary boundary layer (PBL) turbulence in the afternoon, from the time the surface buoyancy flux starts to decrease until sunset. Dense observations of mean and turbulent parameters were acquired during the Boundary Layer Late Afternoon and Sunset Turbulence (BLLAST) field experiment by several meteorological surface stations, sounding balloons, radars, lidars and two aircraft during the afternoon transition. We analysed a case study based on some of these observations and large-eddy simulation (LES) data focusing on the turbulent vertical structure throughout the afternoon transition. The decay of turbulence is quantified through the temporal and vertical evolution of (1) the turbulence kinetic energy (TKE), (2) the characteristic length scales of turbulence and (3) the shape of the turbulence spectra. A spectral analysis of LES data, airborne and surface measurements is performed in order to characterize the variation in the turbulent decay with height and study the distribution of turbulence over eddy size. This study highlights the LES ability to reproduce the turbulence evolution throughout the afternoon. LESs and observations agree that the afternoon transition can be divided in two phases: (1) a first phase during which the TKE decays at a low rate, with no significant change in turbulence characteristics, and (2) a second phase characterized by a larger TKE decay rate and a change in spectral shape, implying an evolution of eddy size distribution and energy cascade from low to high wave number. The changes observed either in TKE decay (during the first phase) or in the vertical wind spectra shape (during the second phase of the afternoon transition) occur first in the upper region of the PBL. The higher within the PBL, the stronger the spectra shape changes.

  16. Resolving Organized Aerosol Structures (Rolls and Layers) with Airborne Fast Mobility Particle Sizer (FMPS) During MILAGRO/INTEX Campaign

    NASA Astrophysics Data System (ADS)

    Kapustin, V.; Clarke, A.; Zhou, J.; Howell, S.; Shinozuka, Y.; Brekhovskikh, V.; McNaughton, C.

    2007-12-01

    The Hawaii Group for Environmental Aerosol Research [http://www.soest.hawaii.edu/HIGEAR] deployed a wide range of aerosol instrumentation aboard the C-130 and the NASA DC-8 as part of MILAGRO/INTEX. These were designed to provide rapid information on aerosol composition, state of mixing (internal or external), spectral optical properties (scattering and absorption), the humidity dependence of light scattering-f(RH), and the role of condensed species in changing the absorption properties of black carbon (BC) and inferred properties of organic carbon (OC). These measurements included size distributions from about 7 nm up to about 10,000 nm and their volatility at 150, 300 and 400 C; size selected response to heating (volatility) to resolve the state of mixing of the aerosol; continuous measurements of the light scattering and absorption at 3 wavelengths; measurements of the f(RH). We also flew the first airborne deployment of the new Fast Mobility Particle Sizer (FMPS, TSI Inc.) that provided information on rapid (1Hz) size variations in the Aitken mode. This revealed small scale structure of the aerosol and allowed us to examine size distributions varying over space and time associated with mixing processes previously unresolved etc. Rapid measurements during profiles also revealed variations in size over shallow layers. Other dynamic processes included rapid size distribution measurements within orographically induced aerosol layers and size distribution evolution of the nanoparticles formed by nucleation (C-130 flights 5, 6 and 9). Evidence for fluctuations induced by underlying changes in topography was also detected. These measurements also frequently revealed the aerosol variability in the presence of boundary layer rolls aligned along the wind in the Marine Boundary Layer (Gulf region) both with and without visible cloud streets (DC-8 flight 4 and C-130 flight 7). This organized convection over 1-2 km scales influences the mixing processes (entrainment, RH

  17. Expanding Curtain Observations of Cloud Vertical Structure and Layering to Model-Relevant Spatial Scales

    NASA Astrophysics Data System (ADS)

    Miller, S.; Bankert, R.; Forsythe, J.; Mitrescu, C.; Reinke, D.; Austin, R.

    2007-12-01

    Clouds, representing perhaps the most obvious physical manifestations of atmospheric dynamics at work, remain in many ways an enigmatic and unifying intellectual challenge to researchers of all disciplines within the atmospheric sciences. Given the universally acknowledged importance of cloud systems in determining the state of current and future climate through radiative, chemical, dynamic, and thermodynamic processes tied intimately to the hydrological cycle, it is no wonder that so much recent attention has been given to better understanding the non-linear feedbacks involving clouds and ways to improve their handling in numerical weather prediction (NWP) models. In terms of operational community interests, knowledge of cloud vertical structure, ceiling (cloud base) height, and phase is key to aviation safety assurance in the private, commercial, and defense-agency sectors alike. The launch of the NASA Earth System Science Pathfinder CloudSat (cloud radar; 3 mm wavelength) mission in 2006 changed forever the way we view cloud systems from the space platform--providing vertically-resolved 'cuts' through the cloudy troposphere. The Cloud Profiling Radar (CPR) system resolves nearly all radiatively significant cloud structures present in the column at vertical resolutions sufficient to afford scientists the opportunity to examine new hypotheses on cloud formation (leading potentially to new/improved cloud process parameterizations) and make observationally-based discoveries bordering on the frontiers of our current understanding. At the same time, the non-scanning nature of the CPR (providing so-called 'curtain' observations) represents in some respects a frustrating tease to the potential of a three-dimensional scanning system, relegating its utility to the realms of research as opposed to full spatial environmental characterization and data assimilation. This research examines ways to extend via statistical methods the curtain slices provided by CloudSat into the

  18. Impact of photonic crystals on LED light extraction efficiency: approaches and limits to vertical structure designs

    SciTech Connect

    Matioli, Elison; Weisbuch, Claude

    2010-08-19

    The enhancement of the extraction efficiency in light emitting diodes (LEDs) through the use of photonic crystals (PhCs) requires a structure design that optimizes the interaction of the guided modes with the PhCs. The main optimization parameters are related to the vertical structure of the LED, such as the thickness of layers, depth of the PhCs, position of the quantum wells as well as the PhC period and fill factor. We review the impact of the vertical design of different approaches of PhC LEDs through a theoretical and experimental standpoint, assessing quantitatively the competing mechanisms that act over each guided mode. Three approaches are described to overcome the main limitation of LEDs with surface PhCs, i.e. the insufficient interaction of low order guided modes with the PhCs. The introduction of an AlGaN confining layer in such structure is shown to be effective in extracting a fraction of the optical energy of low order modes; however, this approach is limited by the growth of the lattice mismatched AlGaN layer on GaN. The second approach, based on thin-film LEDs with PhCs, is limited by the presence of an absorbing reflective metal layer close to the guided modes that plays a major role in the competition between PhC extraction and metal dissipation. Finally, we demonstrate both experimentally and theoretically the superior extraction of the guided light in embedded PhC LEDs due to the higher interaction between all optical modes and the PhCs, which resulted in a close to unity extraction efficiency for this device. The use of high-resolution angle-resolved measurements to experimentally determine the PhC extraction parameters was an essential tool for corroborating the theoretical models and quantifying the competing absorption and extraction mechanisms in LEDs.

  19. Structure and stability of silica particle monolayers at horizontal and vertical octane-water interfaces.

    PubMed

    Horozov, Tommy S; Aveyard, Robert; Binks, Bernard P; Clint, John H

    2005-08-01

    Monolayers of silica particles at horizontal and vertical octane-water interfaces have been studied by microscopy. It is found that their structure and stability depend strongly on the particle hydrophobicity. Very hydrophobic silica particles, with a contact angle of 152 degrees measured through the water, give well-ordered monolayers at interparticle distances larger than 5 particle diameters which are stable toward aggregation and sedimentation. In contrast, monolayers of less-hydrophobic particles are disordered and unstable. Two-dimensional particle sedimentation has been observed in the case of vertical monolayers. The results have been analyzed with a simple two-particle model considering the sedimentation equilibrium as a balance between the long-range electrostatic repulsion through the oil, the gravity force, and the capillary attraction due to deformation of the fluid interface around particles. The value of the charge density at the particle-octane interface, 14.1 muC/m(2), found for the most hydrophobic particles is reasonable. It drastically decreases for particles with lower hydrophobicity, which is consistent with the order-disorder transition in monolayer structure reported by us before. The pair interactions between particles at a horizontal octane-water interface have been analyzed including the capillary attraction due to undulated three-phase contact line caused by nonuniform wetting (the contact angle hysteresis). The results are in agreement with the great stability of very hydrophobic silica particle monolayers detected experimentally, even at low pH at the point of zero charge of the particle-water interface, and with the aggregated structure of hydrophilic particle monolayers.

  20. Aircraft Measurements of Convective System Vertical Structure and Coldpools during the DYNAMO Project

    NASA Astrophysics Data System (ADS)

    Guy, N.; Jorgensen, D. P.; Chen, S. S.; Wang, Q.

    2012-12-01

    The DYNAMO (Dynamics of the Madden-Julian Oscillation) field experiment employed a large number of measurement platforms with which to study environmental and convective cloud system characteristics of the MJO initiation region in the Indian Ocean. One such platform, the NOAA P-3 instrumented aircraft, provided mobility to sample convective cloud systems along with the surrounding environment. The tail-mounted, X-band Doppler radar allowed a pseudo-dual-Doppler analysis technique to study system kinematics and derive vertical wind motion. GPS dropwindsondes provided a robust means for thermodynamic characterization both in and around the sampled convective cloud systems. This presentation will focus on the relationships between coldpool strength and depth (along with other environmental characteristics) and the vertical structure of convective systems. In addition, a comparison of the DYNAMO observations to previous results in the region (e.g. TOGA COARE) will be presented. Differences in organizational aspects of convective clouds into mesoscale convective systems between the studies will provide a context of regional differences, which may serve as a basis for future model simulations.

  1. Vertical structure of turbulence within a depression surrounded by coral reef colonies

    NASA Astrophysics Data System (ADS)

    Huang, Zhi-Cheng

    2015-09-01

    Turbulence is important in coral reefs but is difficult to measure in the field. In this paper, I present in situ measurements of waves, currents, and turbulence to study the vertical structure of turbulence within a depression (curved channel) that is surrounded by coral reef colonies on a fringing reef in Hobihu, Nan-Wan Bay, southern Taiwan. Turbulence was measured using a dual-velocimetry technique, and wave bias contamination in the turbulence is controlled using ogive curve testing of the turbulent shear stress (TSS). The observed turbulent dissipation rate ( ɛ) is approximately five times greater than simultaneous observations over the nearby sandy bottom site, which indicates stronger mixing within the coral reef than on sandy bottoms. The low ratio of the TSS to the turbulent kinetic energy (TKE) and sweeping events indicate that energetic momentum is transported downward into the depression of the coral reef canopies. The observed value of ɛ exceeds the shear production rate, which suggests that transport terms or other source terms might be important. Direct evaluation of the transport terms suggests that vertical turbulent transport and advection are significant mechanisms that diffuse and convect the TKE downward into the depression. The observed TSS can be described well by the Prandtl-von Kármán eddy viscosity model and a two-equation turbulence model, which suggests that it is possible to develop a physically based model to quantify nutrient uptake and mass transfer in coral reefs under complex wave-current coastal flows.

  2. Vertical structure of wave-current turbulence within coral-reef colonies

    NASA Astrophysics Data System (ADS)

    Huang, Zhi-Cheng

    2015-04-01

    We present in situ measurements of waves, currents, and turbulence to study the vertical structure of turbulence within a channel that is surrounded by coral-reef colonies of a fringing reef in Hobihu, Nan-Wan Bay, southern Taiwan. Turbulence was measured using a dual velocimetry technique, and wave bias contamination in the turbulence is controlled using ogive curve testing of the turbulent shear stress (TSS). The observed turbulent dissipation rate is approximately 5 times greater than simultaneous observations over the nearby sandy bottom site, which indicates stronger mixing in the coral reef than on sandy bottoms. The low ratio of the TSS to the turbulent kinetic energy (TKE) and sweeping events indicate that energetic momentum is transported downward into the channel of the coral-reef canopies. The observed value of turbulent dissipation rate exceeds the shear production rate, which suggests that transport terms or other source terms might be important. Direct evaluation of the transport terms suggests that vertical turbulent transport and advection are significant mechanisms that diffuse and convect the TKE downward into the channel. The observed TSS can be described well by the Prandtl-von Kármán eddy viscosity model and a two-equation turbulent model. This study may contribute to other theoretical, observational, and numerical studies in pursuing more understanding and modeling for turbulent mixing of wave-current flows in coastal zones.

  3. VERTICAL KINK OSCILLATION OF A MAGNETIC FLUX ROPE STRUCTURE IN THE SOLAR CORONA

    SciTech Connect

    Kim, S.; Cho, K.-S.; Nakariakov, V. M.

    2014-12-20

    Vertical transverse oscillations of a coronal magnetic rope, observed simultaneously in the 171 Å and 304 Å bandpasses of the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory (SDO), are detected. The oscillation period is about 700 s and the displacement amplitude is about 1 Mm. The oscillation amplitude remains constant during the observation. Simultaneous observation of the rope in the bandpasses corresponding to the coronal and chromospheric temperatures suggests that it has a multi-thermal structure. Oscillatory patterns in 171 Å and 304 Å are coherent, which indicates that the observed kink oscillation is collective, in which the rope moves as a single entity. We interpret the oscillation as a fundamental standing vertically polarized kink mode of the rope, while the interpretation in terms of a perpendicular fast wave could not be entirely ruled out. In addition, the arcade situated above the rope and seen in the 171 Å bandpass shows an oscillatory motion with the period of about 1000 s.

  4. Vertical Structure and Dynamics of the Beaufort Gyre Subsurface Layer from ADCP Obervations

    NASA Astrophysics Data System (ADS)

    Torres, D. J.; Krishfield, R. A.; Proshutinsky, A. Y.; Timmermans, M. L. E.

    2014-12-01

    As part of the Beaufort Gyre Observing System (BGOS), several Acoustic Doppler Current Profilers (ADCPs) have been maintained at moorings in different locations in the Canada Basin since 2005 to measure upper ocean velocities and sea ice motion. The ADCP data have been analyzed to better understand relationships among different components of forcing driving the sea ice and upper ocean layer including: winds, tides, and horizontal and vertical density gradients in the ocean. Specific attention is paid to data processing and analysis to separate inertial and tidal motions in these regions in the vicinity of the critical latitudes. In addition, we describe the dynamic characteristics of halocline eddies and estimate their kinetic energy and their role in the total energy balance in this region. Ice-Tethered Profiler (ITP) data are used in conjunction with the ADCP measurements to identify relationships between T-S and vertical velocity structures in the mixed layer and deeper. Seasonal and interannual variability in all parameters are also discussed and causes of observed changes are suggested.

  5. Effect of Flow and Fluid Structures on the Performance of Vertical River Hydrokinetic Turbines

    NASA Astrophysics Data System (ADS)

    Birjandi, Amir Hossein

    Field and laboratory measurements characterize the performance of vertical axis hydrokinetic turbines operating in uniform and non-uniform inflow conditions for river applications. High sampling frequency velocity measurements, taken at 200 Hz upstream of a stopped and operating 25-kW H-type vertical axis hydrokinetic turbine in the Winnipeg River, show the existence of large eddies with an order of magnitude of the turbine's diameter. Scaling laws allow modeling river conditions in the laboratory for more detailed investigations. A small-scale, 30 cm diameter, squirrel-cage vertical turbine designed, manufactured and equipped with a torque and position sensors is investigated for the detail behavior of the turbine subjected to different inflow conditions in a laboratory setting to study the effect of flow and fluid structures. The adjustable design of the laboratory turbine enables operations with different solidities, 0.33 and 0.67, and preset pitch angles, 0°, +/-2.5°, +/-5° and +/-10°. Tests are first performed with uniform inflow condition to measure the sensitivity of the turbine to solidity, preset pitch angle, free-surface, and Reynolds number to obtain the optimum operating conditions. During the free-surface testing a novel dimensionless coefficient, clearance coefficient, is introduced that relates the change in turbine efficiency with change in the free-surface height. High-speed imaging at 500 fps of semi-submerged blades visualizes the vortex-shedding pattern behind the blades and air entrainment. High-speed imaging results of large eddy pattern behind the vertical turbine are consistent with theory and measurements. Subsequently, cylinders of different diameters create non-uniform inflow conditions in the water tunnel by placing them at different longitudinal and lateral locations upstream of the model turbine. Thus, the effects of non-uniform inflow generated under controlled settings shows the impact of eddies and wake on the turbine

  6. Vertical Profiles of Aerosol Optical and Microphysical Properties During a Rare Case of Long-range Transport of Mixed Biomass Burning-polluted Dust Aerosols from the Russian Federation-kazakhstan to Athens, Greece

    NASA Astrophysics Data System (ADS)

    Papayannis, Alexandros; Argyrouli, Athina; Kokkalis, Panayotis; Tsaknakis, Georgios; Binietoglou, Ioannis; Solomos, Stavros; Kazadzis, Stylianos; Samaras, Stefanos; Böckmann, Christine; Raptis, Panagiotis; Amiridis, Vassilis

    2016-06-01

    Multi-wavelength aerosol Raman lidar measurements with elastic depolarization at 532 nm were combined with sun photometry during the HYGRA-CD campaign over Athens, Greece, on May-June 2014. We retrieved the aerosol optical [3 aerosol backscatter profiles (baer) at 355-532-1064 nm, 2 aerosol extinction (aaer) profiles at 355-532 nm and the aerosol linear depolarization ratio (δ) at 532 nm] and microphysical properties [effective radius (reff), complex refractive index (m), single scattering albedo (ω)]. We present a case study of a long distance transport (~3.500-4.000 km) of biomass burning particles mixed with dust from the Russian Federation-Kazakhstan regions arriving over Athens on 21-23 May 2014 (1.7-3.5 km height). On 23 May, between 2-2.75 km we measured mean lidar ratios (LR) of 35 sr (355 nm) and 42 sr (532 nm), while the mean Ångström exponent (AE) aerosol backscatter-related values (355nm/532nm and 532nm/1064nm) were 2.05 and 1.22, respectively; the mean value of δ at 532 nm was measured to be 9%. For that day the retrieved mean aerosol microphysical properties at 2-2.75 km height were: reff=0.26 μm (fine mode), reff=2.15 μm (coarse mode), m=1.36+0.00024i, ω=0.999 (355 nm, fine mode), ω=0.992(355 nm, coarse mode), ω=0.997 (532 nm, fine mode), and ω=0.980 (532 nm, coarse mode).

  7. High performance vertical tunneling diodes using graphene/hexagonal boron nitride/graphene hetero-structure

    SciTech Connect

    Hwan Lee, Seung; Lee, Jia; Ho Ra, Chang; Liu, Xiaochi; Hwang, Euyheon; Sup Choi, Min; Hee Choi, Jun; Zhong, Jianqiang; Chen, Wei; Jong Yoo, Won

    2014-02-03

    A tunneling rectifier prepared from vertically stacked two-dimensional (2D) materials composed of chemically doped graphene electrodes and hexagonal boron nitride (h-BN) tunneling barrier was demonstrated. The asymmetric chemical doping to graphene with linear dispersion property induces rectifying behavior effectively, by facilitating Fowler-Nordheim tunneling at high forward biases. It results in excellent diode performances of a hetero-structured graphene/h-BN/graphene tunneling diode, with an asymmetric factor exceeding 1000, a nonlinearity of ∼40, and a peak sensitivity of ∼12 V{sup −1}, which are superior to contending metal-insulator-metal diodes, showing great potential for future flexible and transparent electronic devices.

  8. Modeling and control of a cable-suspended robot for inspection of vertical structures

    NASA Astrophysics Data System (ADS)

    Barry, Nicole; Fisher, Erin; Vaughan, Joshua

    2016-09-01

    In this paper, a cable-driven system is examined for the application of inspection of large, vertical-walled structures such as chemical storage tanks, large ship hulls, and high-rise buildings. Such cable-driven systems are not commonly used for these tasks due to vibration, which decreases inspection accuracy and degrades safety. The flexible nature of the cables make them difficult to control. In this paper, input shaping is implemented on a cable-driven system to reduce vibration. To design the input shapers, a model of the cable-driven system was developed. Analysis of the dominant dynamics and changes in them over the large workspace are also presented. The performance improvements provided by the input shaping controller are quantified through a series of simulations.

  9. The vertical structure of the circulation and dynamics in Hudson Shelf Valley

    USGS Publications Warehouse

    Lentz, Steven J.; Butman, Bradford; Harris, Courtney K.

    2014-01-01

    Hudson Shelf Valley is a 20–30 m deep, 5–10 km wide v-shaped submarine valley that extends across the Middle Atlantic Bight continental shelf. The valley provides a conduit for cross-shelf exchange via along-valley currents of 0.5 m s−1 or more. Current profile, pressure, and density observations collected during the winter of 1999–2000 are used to examine the vertical structure and dynamics of the flow. Near-bottom along-valley currents having times scales of a few days are driven by cross-shelf pressure gradients setup by wind stresses, with eastward (westward) winds driving onshore (offshore) flow within the valley. The along-valley momentum balance in the bottom boundary layer is predominantly between the pressure gradient and bottom stress because the valley bathymetry limits current veering. Above the bottom boundary layer, the flow veers toward an along-shelf (cross-valley) orientation and a geostrophic balance with some contribution from the wind stress (surface Ekman layer). The vertical structure and strength of the along-valley current depends on the magnitude and direction of the wind stress. During offshore flows driven by westward winds, the near-bottom stratification within the valley increases resulting in a thinner bottom boundary layer and weaker offshore currents. Conversely, during onshore flows driven by eastward winds the near-bottom stratification decreases resulting in a thicker bottom boundary layer and stronger onshore currents. Consequently, for wind stress magnitudes exceeding 0.1 N m−2, onshore along-valley transport associated with eastward wind stress exceeds the offshore transport associated with westward wind stress of the same magnitude.

  10. The vertical structure of cloud radiative heating over the Indian subcontinent during summer monsoon

    NASA Astrophysics Data System (ADS)

    Johansson, E.; Devasthale, A.; L'Ecuyer, T.; Ekman, A. M. L.; Tjernström, M.

    2015-10-01

    Clouds forming during the summer monsoon over the Indian subcontinent affect its evolution through their radiative impact as well as the release of latent heat. While the latter is previously studied to some extent, comparatively little is known about the radiative impact of different cloud types and the vertical structure of their radiative heating/cooling effects. Therefore, the main aim of this study is to partly fill this knowledge gap by investigating and documenting the vertical distributions of the different cloud types associated with the Indian monsoon and their radiative heating/cooling using the active radar and lidar sensors onboard CloudSat and CALIPSO. The intraseasonal evolution of clouds from May to October is also investigated to understand pre-to-post monsoon transitioning of their radiative heating/cooling effects. The vertical structure of cloud radiative heating (CRH) follows the northward migration and retreat of the monsoon from May to October. Throughout this time period, stratiform clouds radiatively warm the middle troposphere and cool the upper troposphere by more than ±0.2 K day-1 (after weighing by cloud fraction), with the largest impacts observed in June, July and August. During these months, the fraction of high thin cloud remains high in the tropical tropopause layer (TTL). Deep convective towers cause considerable radiative warming in the middle and upper troposphere, but strongly cool the base and inside of the TTL. This cooling is stronger during active (-1.23 K day-1) monsoon periods compared to break periods (-0.36 K day-1). The contrasting radiative warming effect of high clouds in the TTL is twice as large during active periods than in break periods. These results highlight the increasing importance of CRH with altitude, especially in the TTL. Stratiform (made up of alto- and nimbostratus clouds) and deep convection clouds radiatively cool the surface by approximately -100 and -400 W m-2 respectively while warming the

  11. 23 CFR Appendix to Subpart B of... - Horizontal and Vertical Clearance Provisions for Overpass and Underpass Structures

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Overpass and Underpass Structures Appendix to Subpart B of Part 646 Highways FEDERAL HIGHWAY ADMINISTRATION... location. Federal-aid highway funds are also eligible to participate in the cost of providing vertical... electrification will not be eligible for Federal-aid highway fund participation. c. Railroad Structure Width...

  12. 23 CFR Appendix to Subpart B of... - Horizontal and Vertical Clearance Provisions for Overpass and Underpass Structures

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Overpass and Underpass Structures Appendix to Subpart B of Part 646 Highways FEDERAL HIGHWAY ADMINISTRATION... location. Federal-aid highway funds are also eligible to participate in the cost of providing vertical... electrification will not be eligible for Federal-aid highway fund participation. c. Railroad Structure Width...

  13. 23 CFR Appendix to Subpart B of... - Horizontal and Vertical Clearance Provisions for Overpass and Underpass Structures

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Overpass and Underpass Structures Appendix to Subpart B of Part 646 Highways FEDERAL HIGHWAY ADMINISTRATION... location. Federal-aid highway funds are also eligible to participate in the cost of providing vertical... electrification will not be eligible for Federal-aid highway fund participation. c. Railroad Structure Width...

  14. 23 CFR Appendix to Subpart B of... - Horizontal and Vertical Clearance Provisions for Overpass and Underpass Structures

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Overpass and Underpass Structures Appendix to Subpart B of Part 646 Highways FEDERAL HIGHWAY ADMINISTRATION... location. Federal-aid highway funds are also eligible to participate in the cost of providing vertical... electrification will not be eligible for Federal-aid highway fund participation. c. Railroad Structure Width...

  15. Use of the NASA GEOS-5 SEAC4RS Meteorological and Aerosol Reanalysis for assessing simulated aerosol optical properties as a function of smoke age

    NASA Astrophysics Data System (ADS)

    Randles, C. A.; da Silva, A. M., Jr.; Colarco, P. R.; Darmenov, A.; Buchard, V.; Govindaraju, R.; Chen, G.; Hair, J. W.; Russell, P. B.; Shinozuka, Y.; Wagner, N.; Lack, D.

    2014-12-01

    The NASA Goddard Earth Observing System version 5 (GEOS-5) Earth system model, which includes an online aerosol module, provided chemical and weather forecasts during the SEAC4RS field campaign. For post-mission analysis, we have produced a high resolution (25 km) meteorological and aerosol reanalysis for the entire campaign period. In addition to the full meteorological observing system used for routine NWP, we assimilate 550 nm aerosol optical depth (AOD) derived from MODIS (both Aqua and Terra satellites), ground-based AERONET sun photometers, and the MISR instrument (over bright surfaces only). Daily biomass burning emissions of CO, CO2, SO2, and aerosols are derived from MODIS fire radiative power retrievals. We have also introduced novel smoke "age" tracers, which provide, for a given time, a snapshot histogram of the age of simulated smoke aerosol. Because GEOS-5 assimilates remotely sensed AOD data, it generally reproduces observed (column) AOD compared to, for example, the airborne 4-STAR instrument. Constraining AOD, however, does not imply a good representation of either the vertical profile or the aerosol microphysical properties (e.g., composition, absorption). We do find a reasonable vertical structure for aerosols is attained in the model, provided actual smoke injection heights are not much above the planetary boundary layer, as verified with observations from DIAL/HRSL aboard the DC8. The translation of the simulated aerosol microphysical properties to total column AOD, needed in the aerosol assimilation step, is based on prescribed mass extinction efficiencies that depend on wavelength, composition, and relative humidity. Here we also evaluate the performance of the simulated aerosol speciation by examining in situ retrievals of aerosol absorption/single scattering albedo and scattering growth factor (f(RH)) from the LARGE and AOP suite of instruments. Putting these comparisons in the context of smoke age as diagnosed by the model helps us to

  16. Micro-size antenna structure with vertical nanowires for wireless power transmission and communication.

    PubMed

    Kang, Jong-Gu; Jeong, Yeri; Shin, Jeong Hee; Choi, Ji-Woong; Sohn, Jung Inn; Cha, Seung Nam; Jang, Jae Eun

    2014-11-01

    For biomedical implanted devices, a wireless power or a signal transmission is essential to protect an infection and to enhance durability. In this study, we present a magnetic induction technique for a power transmission without any wire connection between transmitter (Tx) and receiver (Rx) in a micro scale. Due to a micro size effect of a flat spiral coil, a magnetic inductance is not high. To enhance the magnetic inductance, a three dimensional magnetic core is added to an antenna structure, which is consisted of ZnO nano wires coated by a nickel (Ni) layer. ZnO nano wires easily supply a large effective surface area with a vertical structural effect to the magnetic core structure, which induces a higher magnetic inductance with a ferro-magnetic material Ni. The magnetic induction antenna with the magnetic core shows a high inductance value, a low reflection power and a strong power transmission. The power transmission efficiencies are tested under the air and the water medium are almost the same values, so that the magnetic induction technique is quite proper to body implanted systems.

  17. Active bacterial community structure along vertical redox gradients in Baltic Sea sediment

    SciTech Connect

    Jansson, Janet; Edlund, Anna; Hardeman, Fredrik; Jansson, Janet K.; Sjoling, Sara

    2008-05-15

    Community structures of active bacterial populations were investigated along a vertical redox profile in coastal Baltic Sea sediments by terminal-restriction fragment length polymorphism (T-RFLP) and clone library analysis. According to correspondence analysis of T-RFLP results and sequencing of cloned 16S rRNA genes, the microbial community structures at three redox depths (179 mV, -64 mV and -337 mV) differed significantly. The bacterial communities in the community DNA differed from those in bromodeoxyuridine (BrdU)-labeled DNA, indicating that the growing members of the community that incorporated BrdU were not necessarily the most dominant members. The structures of the actively growing bacterial communities were most strongly correlated to organic carbon followed by total nitrogen and redox potentials. Bacterial identification by sequencing of 16S rRNA genes from clones of BrdU-labeled DNA and DNA from reverse transcription PCR (rt-PCR) showed that bacterial taxa involved in nitrogen and sulfur cycling were metabolically active along the redox profiles. Several sequences had low similarities to previously detected sequences indicating that novel lineages of bacteria are present in Baltic Sea sediments. Also, a high number of different 16S rRNA gene sequences representing different phyla were detected at all sampling depths.

  18. Micro-size antenna structure with vertical nanowires for wireless power transmission and communication.

    PubMed

    Kang, Jong-Gu; Jeong, Yeri; Shin, Jeong Hee; Choi, Ji-Woong; Sohn, Jung Inn; Cha, Seung Nam; Jang, Jae Eun

    2014-11-01

    For biomedical implanted devices, a wireless power or a signal transmission is essential to protect an infection and to enhance durability. In this study, we present a magnetic induction technique for a power transmission without any wire connection between transmitter (Tx) and receiver (Rx) in a micro scale. Due to a micro size effect of a flat spiral coil, a magnetic inductance is not high. To enhance the magnetic inductance, a three dimensional magnetic core is added to an antenna structure, which is consisted of ZnO nano wires coated by a nickel (Ni) layer. ZnO nano wires easily supply a large effective surface area with a vertical structural effect to the magnetic core structure, which induces a higher magnetic inductance with a ferro-magnetic material Ni. The magnetic induction antenna with the magnetic core shows a high inductance value, a low reflection power and a strong power transmission. The power transmission efficiencies are tested under the air and the water medium are almost the same values, so that the magnetic induction technique is quite proper to body implanted systems. PMID:25958501

  19. Determination of material constants of vertically aligned carbon nanotube structures in compressions.

    PubMed

    Li, Yupeng; Kang, Junmo; Choi, Jae-Boong; Nam, Jae-Do; Suhr, Jonghwan

    2015-06-19

    Different chemical vapour deposition (CVD) fabrication conditions lead to a wide range of variation in the microstructure and morphologies of carbon nanotubes (CNTs), which actually determine the compressive mechanical properties of CNTs. However, the underlying relationship between the structure/morphology and mechanical properties of CNTs is not fully understood. In this study, we characterized and compared the structural and morphological properties of three kinds of vertically aligned carbon nanotube (VACNT) arrays from different CVD fabrication methods and performed monotonic compressive tests for each VACNT array. The compressive stress-strain responses and plastic deformation were first compared and analyzed with nanotube buckling behaviours. To quantify the compressive properties of the VACNT arrays, a strain density energy function was used to determine their intrinsic material constants. Then, the structural and morphological effects on the quantified material constants of the VACNTs were statistically investigated and analogized to cellular materials with an open-cell model. The statistical analysis shows that density, defect degree, and the moment of inertia of the CNTs are key factors in the improvement of the compressive mechanical properties of VACNT arrays. This approach could allow a model-driven CNT synthesis for engineering their mechanical behaviours. PMID:26011574

  20. Determination of material constants of vertically aligned carbon nanotube structures in compressions

    NASA Astrophysics Data System (ADS)

    Li, Yupeng; Kang, Junmo; Choi, Jae-Boong; Nam, Jae-Do; Suhr, Jonghwan

    2015-06-01

    Different chemical vapour deposition (CVD) fabrication conditions lead to a wide range of variation in the microstructure and morphologies of carbon nanotubes (CNTs), which actually determine the compressive mechanical properties of CNTs. However, the underlying relationship between the structure/morphology and mechanical properties of CNTs is not fully understood. In this study, we characterized and compared the structural and morphological properties of three kinds of vertically aligned carbon nanotube (VACNT) arrays from different CVD fabrication methods and performed monotonic compressive tests for each VACNT array. The compressive stress-strain responses and plastic deformation were first compared and analyzed with nanotube buckling behaviours. To quantify the compressive properties of the VACNT arrays, a strain density energy function was used to determine their intrinsic material constants. Then, the structural and morphological effects on the quantified material constants of the VACNTs were statistically investigated and analogized to cellular materials with an open-cell model. The statistical analysis shows that density, defect degree, and the moment of inertia of the CNTs are key factors in the improvement of the compressive mechanical properties of VACNT arrays. This approach could allow a model-driven CNT synthesis for engineering their mechanical behaviours.

  1. Vertical structure of aeolian turbulence in a boundary layer with sand transport

    NASA Astrophysics Data System (ADS)

    Lee, Zoe S.; Baas, Andreas C. W.

    2016-04-01

    Recently we have found that Reynolds shear stress shows a significant variability with measurement height (Lee and Baas, 2016), and so an alternative parameter for boundary layer turbulence may help to explain the relationship between wind forcing and sediment transport. We present data that were collected during a field study of boundary layer turbulence conducted on a North Atlantic beach. High-frequency (50 Hz) 3D wind velocity measurements were collected using ultrasonic anemometry at thirteen different measurement heights in a tight vertical array between 0.11 and 1.62 metres above the surface. Thanks to the high density installation of sensors a detailed analysis of the boundary layer flow can be conducted using methods more typically used in studies where data is only available from one or just a few measurement heights. We use quadrant analysis to explore the vertical structure of turbulence and track the changes in quadrant signatures with measurement elevation and over time. Results of quadrant analysis, at the 'raw' 50 Hz timescale, demonstrates the tendency for event clustering across all four quadrants, which implies that at-a-point quadrant events are part of larger-scale turbulent structures. Using an HSV colour model, applied to the quadrant analysis data and plotted in series, we create colour maps of turbulence, which can provide a clear visualisation of the clustering of event activity at each height and illustrate the shape of the larger coherent flow structures that are present within the boundary layer. By including a saturation component to the colour model, the most significant stress producing sections of the data are emphasised. This results in a 'banded' colour map, which relates to clustering of quadrant I (Outward Interaction) and quadrant IV (Sweep) activity, separate from clustering of quadrant II (Burst) and quadrant III (Inward Interaction). Both 'sweep-type' and 'burst-type' sequences are shown to have a diagonal structure

  2. Observational definition of the Venus mesopause: vertical structure, diurnal variation, and temporal instability

    NASA Astrophysics Data System (ADS)

    Clancy, R. T.; Sandor, B. J.; Moriarty-Schieven, G. H.

    2003-01-01

    Submillimeter line observations of CO in the Venus middle atmosphere (mesosphere) were observed with the James Clerk Maxwell Telescope (JCMT, Mauna Kea) about the May 2000, February 2002 superior and July 1999, March 2001 inferior conjunctions of Venus. Combined 12CO and 13CO isotope spectral line measurements at 345 and 330 gHz frequencies, respectively, provided enhanced sensitivity and vertical coverage for simultaneous retrievals of atmospheric temperatures and CO mixing ratios over the altitude region 75-105 km with vertical resolution 4-5 km. Supporting millimeter 12CO spectral line observations with the Kitt Peak 12-m telescope (Steward Observatories) provide enhanced temporal coverage and CO mixing sensitivity. Implementation of CO/temperature profile retrievals for the 2000, 2002 dayside (superior conjunction) and 1999, 2001 nightside (inferior conjunction) periods yields a first-time definition of the vertical structure and diurnal variation of a low-to-mid-latitude mesopause within the Venus atmosphere. At the times of these 1999-2002 observations, the Venus mesopause was located at a slightly lower level in the nightside (0.5 mbar, ˜87 km) versus the dayside (0.2 mbar, ˜91 km) atmosphere. Average diurnal variation of Venus mesospheric temperatures appears to be ≤ 5 K at and below the mesopause. Diurnal variation of Venus thermospheric temperatures increases abruptly just above the mesopause, reaching 50 K by the 0.01-mbar pressure level (˜102 km). Atmospheric temperatures above and below the Venus mesopause exhibited global-scale (≥4000 km horizontal) variations of large amplitude (7-15 K) on surprisingly short timescales (daily to monthly) during the 2001 nightside and 2002 dayside observing periods. Venus dayside mesospheric temperatures observed during the 2002 superior conjunction were also 10-15 K warmer than observed during the 2000 superior conjunction. A characteristic timescale for these global temperature variations is not defined, but

  3. Vertical structure of predictability and information transport over the Northern Hemisphere

    NASA Astrophysics Data System (ADS)

    Feng, Ai-Xia; Wang, Qi-Gang; Gong, Zhi-Qiang; Feng, Guo-Lin

    2014-02-01

    Based on nonlinear prediction and information theory, vertical heterogeneity of predictability and information loss rate in geopotential height field are obtained over the Northern Hemisphere. On a seasonal-to-interannual time scale, the predictability is low in the lower troposphere and high in the mid-upper troposphere. However, within mid-upper troposphere over the subtropics ocean area, there is a relatively poor predictability. These conclusions also fit the seasonal time scale. Moving to the interannual time scale, the predictability becomes high in the lower troposphere and low in the mid-upper troposphere, contrary to the former case. On the whole the interannual trend is more predictable than the seasonal trend. The average information loss rate is low over the mid-east Pacific, west of North America, Atlantic and Eurasia, and the atmosphere over other places has a relatively high information loss rate on all-time scales. Two channels are found steadily over the Pacific Ocean and Atlantic Ocean in subtropics. There are also unstable channels. The four-season influence on predictability and information communication are studied. The predictability is low, no matter which season data are removed and each season plays an important role in the existence of the channels, except for the winter. The predictability and teleconnections are paramount issues in atmospheric science, and the teleconnections may be established by communication channels. So, this work is interesting since it reveals the vertical structure of predictability distribution, channel locations, and the contributions of different time scales to them and their variations under different seasons.

  4. Three Dimensional Aerosol Climatology over India and the North Indian Ocean

    NASA Astrophysics Data System (ADS)

    Adams, A.; Zhang, C.

    2013-12-01

    Numerical models are indispensable tools to study aerosol effects on climate, including both aerosol direct and indirect radiative effects and their role in precipitation. But, agreement among the models has not been achieved, and thus it is not possible to accurately and confidently attain estimates of aerosol effects on climate. The lack of reliable knowledge on global three-dimensional (3D) aerosol climatology has prevented us from assessing the degree to which the disagreement in their aerosol climatic effects may come from differences of aerosol vertical structures in their simulations. To that end, we created a six year, global 3D extinction coefficient dataset for each aerosol species identifiable by the Level 2, Version 3, 5 km Aerosol Profile product from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) onboard Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) as a tool to improve 3D model representations. Here we describe the 3D structure of aerosol in the Middle East, India, and the Northern Indian Ocean and some of the interesting dynamical features responsible for the vertical structure and external mixing of aerosol species. One interesting feature in the 3D structure during boreal summer is a well-defined EC core located 0 - 10°N, 40°E - 90°E (Somalia across the Indian subcontinent), centered at 3 km. This is controlled by a shallow meridional circulation about the core. Additionally, the Somali Low-Level Jet exists at this location, but is usually located below the core (~850 mb). Another interesting feature is a strong EC core located 0 - 15°N, 60°E - 90°E below 0.5 km. Polluted dust (external mixture of dust and smoke) and marine aerosol are collocated in this area with maximum AODs of ~0.5 and ~0.2 respectively. Due to the wind stress over ocean, collocation of aerosol species, altitude, and lack of transport pathway for polluted dust, it is possible that this is an example of aerosol misclassification by

  5. Ecohydrological responses of dense canopies to environmental variability: 1. Interplay between vertical structure and photosynthetic pathway

    NASA Astrophysics Data System (ADS)

    Drewry, D. T.; Kumar, P.; Long, S.; Bernacchi, C.; Liang, X.-Z.; Sivapalan, M.

    2010-12-01

    Vegetation acclimation to changing climate, in particular elevated atmospheric concentrations of carbon dioxide (CO2), has been observed to include modifications to the biochemical and ecophysiological functioning of leaves and the structural components of the canopy. These responses have the potential to significantly modify plant carbon uptake and surface energy partitioning, and have been attributed with large-scale changes in surface hydrology over recent decades. While the aggregated effects of vegetation acclimation can be pronounced, they often result from subtle changes in canopy properties that require the resolution of physical, biochemical and ecophysiological processes through the canopy for accurate estimation. In this paper, the first of two, a multilayer canopy-soil-root system model developed to capture the emergent vegetation responses to environmental change is presented. The model incorporates both C3 and C4 photosynthetic pathways, and resolves the vertical radiation, thermal, and environmental regimes within the canopy. The tight coupling between leaf ecophysiological functioning and energy balance determines vegetation responses to climate states and perturbations, which are modulated by soil moisture states through the depth of the root system. The model is validated for three growing seasons each for soybean (C3) and maize (C4) using eddy-covariance fluxes of CO2, latent, and sensible heat collected at the Bondville (Illinois) Ameriflux tower site. The data set provides an opportunity to examine the role of important environmental drivers and model skill in capturing variability in canopy-atmosphere exchange. Vertical variation in radiative states and scalar fluxes over a mean diurnal cycle are examined to understand the role of canopy structure on the patterns of absorbed radiation and scalar flux magnitudes and the consequent differences in sunlit and shaded source/sink locations through the canopies. An analysis is made of the impact of

  6. Using computerized tomography to determine ionospheric structures. Part 2, A method using curved paths to increase vertical resolution

    SciTech Connect

    Vittitoe, C.N.

    1993-08-01

    A method is presented to unfold the two-dimensional vertical structure in electron density by using data on the total electron content for a series of paths through the ionosphere. The method uses a set of orthonormal basis functions to represent the vertical structure and takes advantage of curved paths and the eikonical equation to reduce the number of iterations required for a solution. Curved paths allow a more thorough probing of the ionosphere with a given set of transmitter and receiver positions. The approach can be directly extended to more complex geometries.

  7. Vertical and Horizontal Wind Structure Prior to and During the 1997/1998 ENSO Event

    NASA Technical Reports Server (NTRS)

    Adamec, David

    1998-01-01

    Analyses of ECMWF and satellite wind products are used to investigate low frequency fluctuations in the wind fields immediately preceding and during the 1997/1998 ENSO event. An extended EOF analysis of the horizontal and vertical wind structure that allows for the study of propagating features indicates that the dominant mode of variability established in the lower levels of the atmosphere is a convergence in the central tropical Pacific. At mid-levels, the westerlies increase with time over most of the equatorial Pacific, and there are closed cyclonic features on either side of the equator. At upper levels, the flow tends to become divergent across the equatorial Pacific, and there is a strong flow from the northwest Pacific across Indonesia that then turns to the west along the equator in the Indian Ocean. The addition of satellite data for improved surface wind estimates reveal that the Indian Ocean winds were anomalously strong during the winter preceding the initiation of the ENSO event. An analysis of the momentum convergence flux at the surface indicates a very strong anomaly 9 months prior to the ENSO event that begins in the western Indian Ocean and propagates to the east, arriving over the Pacific warm pool area coincident with the beginning of the El Nino. Changes in the near surface thermal and water vapor structure over the Indian Ocean during this period will also be discussed.

  8. Vertical Structure of Jupiter's Atmosphere at the Galileo Probe Entry Latitude

    NASA Astrophysics Data System (ADS)

    Chanover, N. J.; Kuehn, D. M.; Beebe, R. F.

    1997-08-01

    The vertical structure of Jupiter's atmosphere is examined to better characterize the latitudinal region of the Galileo probe entry site: +5°-10° planetographic latitude. One-hundred Hubble Space Telescope images of Jupiter taken with the 893- and 953-nm filters on 13 and 17 February 1995, 5 October 1995, and 14 May 1996 are analyzed, and a two-cloud model of the jovian atmosphere (D. M. Kuehn and R. F. Beebe 1993,Icarus101,282-292) is used to interpret center-to-limb variations of bright plume heads and adjacent dark areas in the latitude region +2°-10°. For both the plume heads and dark areas, the top of the ammonia cloud deck reaches a pressure level of roughly 200 mbar, and the cloud has an optical depth of between 6 and 7. The optical depth of the stratospheric haze layer is 0.59 for the plumes and 0.34 for the dark regions, while the single scattering albedo of the ammonia cloud deck is 0.996 for the plumes and 0.950 for the dark regions. Sensitivity tests motivated by the preliminary results from the Galileo probe net flux radiometer and nephelometer experiments indicate that the ammonia cloud deck may have a patchy structure.

  9. Vertical structure of the phytoplankton community associated with a coastal plume in the Gulf of Mexico

    USGS Publications Warehouse

    Wawrik, B.; Paul, J.H.; Campbell, L.; Griffin, D.; Houchin, L.; Fuentes-Ortega, A.; Muller-Karger, F.

    2003-01-01

    Low salinity plumes of coastal origin are occasionally found far offshore, where they display a distinct color signature detectable by satellites. The impact of such plumes on carbon fixation and phytoplankton community structure in vertical profiles and on basin wide scales is poorly understood. On a research cruise in June 1999, ocean-color satellite-images (Sea-viewing Wide Field-of-view Sensor, SeaWiFS) were used in locating a Mississippi River plume in the eastern Gulf of Mexico. Profiles sampled within and outside of the plume were analyzed using flow cytometry, HPLC pigment analysis and primary production using 14C incorporation. Additionally, RubisCO large subunit (rbcL) gene expression was measured by hybridization of extracted RNA using 3 full-length RNA gene probes specific for individual phytoplankton clades. We also used a combination of RT-PCR/PCR and TA cloning in order to generate cDNA and DNA rbcL clone libraries from samples taken in the plume. Primary productivity was greatest in the low salinity surface layer of the plume. The plume was also associated with high Synechococcus counts and a strong peak in Form IA rbcL expression. Form IB rbcL (green algal) mRNA was abundant at the subsurface chlorophyll maximum (SCM), whereas Form ID rbcL (chromophytic) expression showed little vertical structure. Phylogenetic analysis of cDNA libraries demonstrated the presence of Form IA rbcL Synechococcus phylotypes in the plume. Below the plume, 2 spatially separated and genetically distinct rbcL clades of Prochlorococcus were observed. This indicated the presence of the high- and low-light adapted clades of Prochlorococcus. A large and very diverse clade of Prymnesiophytes was distributed throughout the water column, whereas a clade of closely related prasinophytes may have dominated at the SCM. These data indicate that the Mississippi river plume may dramatically alter the surface picoplankton composition of the Gulf of Mexico, with Synechococcus displacing

  10. The 2009-2010 fade of Jupiter's South Equatorial Belt: Vertical cloud structure models and zonal winds from visible imaging

    NASA Astrophysics Data System (ADS)

    Pérez-Hoyos, S.; Sanz-Requena, J. F.; Barrado-Izagirre, N.; Rojas, J. F.; Sánchez-Lavega, A.; IOPW Team

    2012-01-01

    The South Equatorial Belt (SEB) of Jupiter is known to alternate its appearance at visible wavelengths from a classical belt-like band most of the time to a short-lived zone-like aspect which is called a "fade" of the belt, hereafter SEBF. The albedo change of the SEB is due to a change in the structure and properties of the clouds and upper hazes. Recent works based on infrared observations of the last SEBF have shown that the aerosol density below 1 bar increased in parallel with the reflectivity change. However, the nature of the change in the upper clouds and hazes that produces the visible reflectivity change and whether or not this reflectivity change is accompanied by a change in the winds at the upper cloud level remained unknown. In this paper we focus in the near ultraviolet to near infrared reflected sunlight (255-953 nm) to address these two issues. We characterize the vertical cloud structure above the ammonia condensation level from Hubble Space Telescope images, and the zonal wind velocities from long-term high-quality images coming from the International Outer Planet Watch database, both during the SEB and SEBF phases. We show that reflectivity changes do not happen simultaneously in this wavelength range, but they start earlier in the most deep-sensing filters and end in 2010 with just minor changes in those sensing the highest particle layers. Our models require a substantial increase of the optical thickness of the cloud deck at 1.0 ± 0.4 bar from τ cloud = 6 ± 2 in July 2009 (SEB phase) to semiinfinite at visual wavelengths in 2010 (SEBF). Upper tropospheric particles (˜240-1400 mbar) are also required to become substantially reflectant and their single scattering albedo in the blue changes from ϖ0 = 0.905 ± 0.005 in November 2009 to ϖ0 = 0.95 ± 0.01 in June 2010. No significant changes were found in the cloud top heights or in the particle density of the tropospheric haze. The disturbance travels from the levels below ˜3 bar to a level

  11. The vertical turbulence structure of the coastal marine atmospheric boundary layer

    SciTech Connect

    Tjernstroem, M.; Smedman, A.S. )

    1993-03-15

    The vertical turbulence structure in the marine atmosphere along a shoreline has been investigated using data from tower and aircraft measurements performed along the Baltic coast in the southeast of Sweden. Two properties make the Baltic Sea particularly interesting. It is surrounded by land in all directions within moderate advection distances, and it features a significant annual lag in sea surface temperature as compared with inland surface temperature. The present data were collected mostly during spring or early summer, when the water is cool, i.e., with a stably or neutrally stratified marine boundary layer usually capped by an inversion. Substantial daytime heating over the land area results in a considerable horizontal thermal contrast. Measurements were made on a small island, on a tower with a good sea fetch, and with an airborne instrument package. The profile data from the aircraft is from 25 slant soundings performed in connection to low level boundary layer flights. The results from the profiles are extracted through filtering techniques on individual time (space) series (individual profiles), applying different normalization and finally averaging over all or over groups of profiles. The land-based data are from a low tower situated on the shoreline of a small island with a wide sector of unobstructed sea fetch. Several factors are found that add to the apparent complexity of the coastal marine environment: the state of the sea appears to have a major impact on the turbulence structure of the surface layer, jet-shaped wind speed profiles were very common at the top of the boundary layer (in about 50% of the cases) and distinct layers with increased turbulence were frequently found well above the boundary layer (in about 80% of the cases). The present paper will concentrate on a description of the experiment, the analysis methods, and a general description of the boundary layer turbulence structure over the Baltic Sea. 40 refs., 16 figs., 2 tabs.

  12. Fabrication and characterization of aerosol-jet printed strain sensors for multifunctional composite structures

    NASA Astrophysics Data System (ADS)

    Zhao, Da; Liu, Tao; Zhang, Mei; Liang, Richard; Wang, Ben

    2012-11-01

    Traditional multifunctional composite structures are produced by embedding parasitic parts, such as foil sensors, optical fibers and bulky connectors. As a result, the mechanical properties of the composites, especially the interlaminar shear strength (ILSS), could be largely undermined. In the present study, we demonstrated an innovative aerosol-jet printing technology for printing electronics inside composite structures without degrading the mechanical properties. Using the maskless fine feature deposition (below 10 μm) characteristics of this printing technology and a pre-cure protocol, strain sensors were successfully printed onto carbon fiber prepregs to enable fabricating composites with intrinsic sensing capabilities. The degree of pre-cure of the carbon fiber prepreg on which strain sensors were printed was demonstrated to be critical. Without pre-curing, the printed strain sensors were unable to remain intact due to the resin flow during curing. The resin flow-induced sensor deformation can be overcome by introducing 10% degree of cure of the prepreg. In this condition, the fabricated composites with printed strain sensors showed almost no mechanical degradation (short beam shearing ILSS) as compared to the control samples. Also, the failure modes examined by optical microscopy showed no difference. The resistance change of the printed strain sensors in the composite structures were measured under a cyclic loading and proved to be a reliable mean strain gauge factor of 2.2 ± 0.06, which is comparable to commercial foil metal strain gauge.

  13. The vertical distribution of PM2.5 and boundary-layer structure during summer haze in Beijing

    NASA Astrophysics Data System (ADS)

    Sun, Yang; Song, Tao; Tang, Guiqian; Wang, Yuesi

    2013-08-01

    Between August 1, 2009, and August 16, 2009, physical observations of the atmospheric boundary layer and synchronous vertical observations of atmospheric particles were conducted from the Beijing 325 m meteorological tower, where the particulate matter with a diameter of 2.5 μm or less (PM2.5) analysis meters were stationed at a three-floor platform with altitudes of 8 m, 120 m and 280 m, respectively. Meanwhile, the atmospheric temperatures, relative humidity, wind speeds and wind directions between 8 m and 320 m were observed online at 15 different altitude intervals. The backscattering coefficient of aerosols in the boundary-layer atmosphere within 2.5 km height was also observed using a backscattered laser ceilometer. The observations showed that the PM2.5 pollution in the atmosphere from the ground up to 280 m in Beijing was quite high on August 2009, with a maximum of 200 μg m-3. Within 280 m, the vertical distribution of PM2.5 was inhomogeneous, with a maximum difference of up to 116 μg m-3 between levels in the night residual layer and at the ground. The high concentration of particles in the residual layer reached the ground by the next morning through convection, thus becoming severe pollutants. The PM2.5 in the near-surface layer was directly related to the reduction of ultra-violet radiation (UV), with a correlation coefficient of -0.57. Under steady weather conditions, the topographic mountain-valley breezes in Beijing superposed the land-sea breezes, resulting in a specific breath-like diurnal variation in wind direction. As a result, the PM2.5 mixed and increased in the regional area, leading to serious dust-haze pollution. Within 320 m of the boundary layer, the vertical distributions of temperature, humidity, wind speed and wind direction were inhomogeneous, and these patterns were the major factors influencing the distribution and variation of PM2.5 concentration. Under steady weather conditions, the reverse distribution of relative humidity

  14. Forest Vertical Structure from Discrete Lidar, LVIS, and the Ideal Tree Distribution Model

    NASA Astrophysics Data System (ADS)

    Bradley, E.; Roberts, D.; Roth, K.; Parker, G.

    2008-12-01

    Forest height and structure are important variables in the consideration of the global carbon cycle and biodiversity. Both discrete return and large footprint waveform lidar instruments can provide three dimensional information, with discrete return lidar providing higher spatial resolution in the horizontal plane and waveform lidar resulting in more detailed vertical information but for a larger area. Both systems have been used to quantify forest characteristics, however, due to the limited waveform data available, few studies have directly compared these systems. This research seeks to address this deficiency by utilizing NASA's 2003 Laser Vegetation Imaging Sensor (LVIS) waveform data acquired over the Smithsonian Environmental Research Center forest, Maryland, USA, in combination with multi-return discrete lidar and stem plot data. To compare the two systems, linear regressions of height-based lidar metrics were made and quantitative measures of waveform agreement were calculated following the generation of synthetic waveforms from the discrete return data. The LVIS 100% waveform energy height showed a strong agreement with the discrete return maximum canopy height (r2=0.88) and the average cross-waveform correlation was 0.86. For validation, the lidar canopy height model was compared to stem height estimates and digital canopy models generated from diameter data. Using the Purves et al. Ideal Tree Distribution model was superior to site- specific, general-species allometric equations in terms of agreement with the lidar-derived height.

  15. [Landscape quality evaluation and vertical structure optimization of natural broadleaf forest].

    PubMed

    Ouyang, Xun-zhi; Liao, Wei-ming; Peng, Shi-kui

    2007-06-01

    Taking the natural broadleaf forest in Wuyuan County of Jiangxi Province as study object, a total of 30 representative photos of near-view landscapes and related information were collected. The scenic beauty values were acquired by public judgment method, and the relationship models of scenic beauty values and landscape elements were established by using multiple mathematical model. The results showed that the main elements affecting the near-view landscape quality of natural broadleaf forest were the trunk form, stand density, undergrowth coverage and height, natural pruning, and color richness, with the partial correlation coefficients being 0.4482-0.7724, which were significant or very significant by t-test. The multiple correlation coefficient of the model reached 0.9508, showing very significant by F test (F = 36.11). Straight trunk, better natural pruning and rich color did well, while the super-high or low stand density and undergrowth coverage and height did harm to the scenic beauty. Several management measures for the vertical structure optimization of these landscape elements were put forward.

  16. Mesospheric vertical thermal structure and winds on Venus from HHSMT CO spectral-line observations

    NASA Astrophysics Data System (ADS)

    Rengel, Miriam; Hartogh, Paul; Jarchow, Christopher

    2008-08-01

    We report vertical thermal structure and wind velocities in the Venusian mesosphere retrieved from carbon monoxide ( 12CO J=2-1 and 13CO J=2-1) spectral line observations obtained with the Heinrich Hertz Submillimeter Telescope (HHSMT). We observed the mesosphere of Venus from two days after the second Messenger flyby of Venus (on 5 June 2007 at 23:10 UTC) during five days. Day-to-day and day-to-night temperature variations and short-term fluctuations of the mesospheric zonal flow were evident in our data. The extensive layer of warm air detected recently by SPICAV at 90-100 km altitude is also detected in the temperature profiles reported here. These data were part of a coordinated ground-based Venus observational campaign in support of the ESA Venus Express mission. Furthermore, this study attempts to cross-calibrate space- and ground-based observations, to constrain radiative transfer and retrieval algorithms for planetary atmospheres, and to contribute to a more thorough understanding of the global patterns of circulation of the Venusian atmosphere.

  17. A Study of the Vertical Structure of Tropical (20 deg S-20 deg N) Optically Thin Clouds from SAGE II Observations

    NASA Technical Reports Server (NTRS)

    Wang, Pi-Huan; Minnis, Patrick; McCormick, M. Patrick; Kent, Geoffrey S.; Yue, Glenn K.; Young, David F.; Skeens, Kristi M.

    1998-01-01

    The tropical cloud data obtained by the satellite instrument of the Stratospheric Aerosol and Gas Experiment (SAGE) II from October 1984 to May 1991 have been used to study cloud vertical distribution, including thickness and multilayer structure, and to estimate cloud optical depth. The results indicate that the SAGE-II-observed clouds are generally optically thin clouds, corresponding to a range of optical depth between approximately 8 x 10(exp -4) and 3 x 10(exp -1) with a mean of about 0.035. Two-thirds are classified as subvisual cirrus and one-third thin cirrus. Clouds between 2- to 3-km thick occur most frequently. Approximately 30% of the SAGE II cloud measurements are isolated single-layer clouds, while 65% are high clouds contiguous with an underlying opaque cloud that terminates the SAGE II profile. Thin clouds above detached opaque clouds at altitudes greater than 6.5 km occur less often. Only about 3% of the SAGE II single-layer clouds are located above the tropopause, while 58% of the cloud layers never reach the tropopause. More than one-third of the clouds appear at the tropopause. This study also shows that clouds occur more frequently and extend higher above the tropopause over the western Pacific than than over the eastern Pacific, especially during northern winter. The uncertainty of the derived results due to the SAGE II sampling constraints, data processing, and cloud characteristics is discussed.

  18. Characterization of preferential flow in undisturbed, structured soil columns using a vertical TDR probe.

    PubMed

    Lee, J; Horton, R; Noborio, K; Jaynes, D B

    2001-10-01

    Rapid movement of agricultural chemicals through soil to groundwater via preferential flow pathways is one cause of water contamination. Previous studies have shown that time domain reflectometry (TDR) could be used to characterize solute transport in soil. However, previous studies have only scarcely addressed preferential flow. This study presents an extended application of TDR for determining preferential flow properties. A TDR method was tested in carefully controlled laboratory experiments using 20-cm long and 12-cm diameter undisturbed, structured soil columns. The method used a vertically installed TDR probe and a short pulse of tracer application to obtain residual mass (RM) breakthrough curves (BTC). The RM BTC obtained from TDR were used to estimate mobile/immobile model (MIM) parameters that were compared to the parameter estimates from effluent data. A conventional inverse curve fitting method (CXTFIT) was used to estimate parameters. The TDR-determined parameters were then used to generate calculated effluent BTC for comparison with observed effluent BTC for the same soil columns. Time moments of the calculated and observed BTC were calculated to quantitatively evaluate the calculated BTC. Overall, the RM BTC obtained from TDR were similar to the RM BTC obtained from effluent data. The TDR-determined parameters corresponded well to the parameters obtained from the effluent data, although they were not within the 95% confidence intervals. Correlation coefficients between the parameters obtained from TDR and from effluent data for the immobile water fraction (theta im/theta), mass exchange coefficient (alpha), and dispersion coefficient (Dm) were 0.95, 0.95, and 0.99, respectively. For three of the four soil cores, theta im/theta ranged from 0.42 to 0.82, indicating considerable preferential flow. The TDR-calculated effluent BTC also were similar to the observed effluent BTC having an average coefficient of determination of 0.94. Time moments obtained

  19. Vertical Structure and Physical Processes of the Madden-Julian Oscillation: A Model Evaluation Project

    NASA Astrophysics Data System (ADS)

    Woolnough, S. J.; Waliser, D. E.; Klingaman, N. P.; Jiang, X.; Petch, J.; Xavier, P. K.

    2014-12-01

    The fundamental physics of the generation, maintenance and propagation of the Madden-Julian Oscillation are intensely debated. Many theories focus on instabilities arising from interactions between components of the vertical diabatic heating from convection and the large-scale circulation. Most general circulation models (GCMs) exhibit biases in diabatic-heating profiles against observed or reanalysis products, but those products also exhibit considerable discrepancies with one another. The Vertical structure and physical processes of the MJO project is a novel model-evaluation project, designed to assess relationships between diabatic processes in GCMs and their representations of the MJO. A key advantage of the project is the acquisition of temperature, moisture and momentum tendencies from each of the model sub-grid physics schemes. The project has three components, designed to take advantage of known links between biases in short-range forecasts and climate simulations: (1) 20-year AMIP-type simulations to assess the representation of the MJO in each GCM; (2) 2-day hindcasts of two YoTC MJO events to investigate the timestep-level behaviour of physical parameterisations; (3) 20-day hindcasts of the same events to identify links between degradations in forecast skill and the representation of diabatic processes. Analysis of the three component has identified several over-arching conclusions. First, many process-oriented MJO diagnostics derived from past studies using one or several GCMs fail to distinguish between the GCMs in this project that simulate the MJO well and those that do so poorly, whether for initialised hindcasts or 20-year simulations. Second, there is little correlation between GCM hindcast skill for these cases and the fidelity of the MJO representation in climate simulations. Third, all three components have demonstrated that a reliable representation of the moistening profile, particularly lower- and mid-tropospheric moistening during the

  20. A Block-Structured KIVA Program for Engines with Vertical or Canted Valves

    1999-08-23

    KIVA3VRELEASE2 is a computer program for the numerical calculation of transient, two and three-dimensional, chemically reactive flows with sprays. It is a newer version of the earlier KIVA3 (1993) that has now been extended to model vertical of canted valves in the cylinder head of a gasoline or diesel engine. KIVA3, in turn, was based on the earlier KIVA2 (1989) and uses the same numerical solution procedure and solves the same sort of equations. KIVA3VRELEASE2more » uses a block-structured mesh with connectivity defined through indirect addressing. The departure from a single rectangular structure in logical space allows complex geometries to be modeled with significantly greater efficiency because large regions of deactivated cells are no longer necessary. Cell-face boundary conditions permit greater flexibility and simplification in the application of boundary conditions. KIVA3VRELEASE2 contains a number of significant changes. New features enhance the robustness, efficiency, and usefullness of the overall program for engine modeling. Automatic restart of the cycle with a reduced timestep in case of iteration limit or temperature overflow will reduce code crashes. A new option provides automatic deactivation of a port region when it is closed from the cylinder and reactivation when it communicates with the cylinder. Corrections in the code improve accuracy; extensions to the particle-based liquid wall film model makes the model more complete and a spli injection option has been added. A new subroutine monitors the liquid and gaseous fuel phases and energy balance data and emissions are monitored and printed. New features have been added to the grid generator K3PREP and the graphics post processor, K3POST.« less

  1. Chitinolytic and pectinolytic community in the vertical structure of chernozem's zone ecosystems

    NASA Astrophysics Data System (ADS)

    Lukacheva, E.; Manucharova, N.

    2012-04-01

    Chitin is a long-chain polymer of a N-acetylglucosamine and is found in many places throughout the natural world. Pectin is a structural heteropolysaccharide contained in the primary cell walls of terrestrial plants. Roots of the plants and root crops contain pectin. Chitin and pectin are widely distributed throughout the natural world. For this reason it is important to investigate the structural and functional properties of complex organisms, offering degradation of these biopolymers in the terrestrial and soil ecosystems. It is known that ecosystems have their own structure. It is possible to allocate some vertical tiers: phylloplane, litter (soil covering), soil. We investigated chitinolytic and pektinolytic microbial communities dedicated to different layers of the ecosystem of the chernozem zone. Quantity of eukaryote and procaryote organisms increased in the test samples with chitin and pectin. Increasing of eukaryote in samples with pectin was more then in samples with chitin. Also should be noted the significant increasing of actinomycet`s quantity in the samples with chitin in comparison with samples with pectin. The variety and abundance of bacteria in the litter samples increased an order of magnitude as compared to other options investigated. Further prokaryote community was investigated by method FISH (fluorescence in situ hybridization). FISH is a cytogenetic technique developed that is used to detect and localize the presence or absence of specific DNA sequences on chromosomes. Quantity of Actinomycets and Firmicutes was the largest among identified cells with metabolic activity in soil samples. Should be noted significant increasing of the quantity of Acidobateria and Bacteroidetes in pectinolytic community and Alphaproteobacteria in chitinolytic community. In considering of the phylogenetic structure investigated communities in samples of the litter should be noted increase in the segment of Proteobacteria. Increasing of this group of

  2. Impact of vertical structure on water mass circulation in a tropical lagoon (Ebrié, Ivory Coast)

    NASA Astrophysics Data System (ADS)

    Brenon, Isabelle; Audouin, Olivier; Pouvreau, Nicolas; Maurin, Jean-Christophe

    2009-09-01

    A one-dimensional vertical model has been developed to simulate the water mass circulation along the vertical structure in all deep coastal areas. The model has hydrodynamic and transport components solved using finite difference scheme. The one-dimensional vertical model results are coupled to the vertically averaged two-dimensional model results at each point of a horizontal grid. A theoretical salinity profile is introduced for each vertically integrated value obtained from the 2DH model results. A viscosity profile, simulating a viscosity value close to zero at the surface and with large viscosity gradients, is applied along the water column. The model is applied to the Vridi channel, connecting the Ebrié lagoon to the sea (Ivory Coast). The response of the Ebrié lagoon is studied in terms of inflow and outflow of water in the system through the Vridi channel. Due to the abrupt variation of the surface slope, vertical velocities along the water column show an anticlockwise spiral from bottom to surface during a tidal cycle. Due to the bottom friction and to the vertical viscosity profile, velocities decrease from surface to bottom. However, the freshwater inflow slows down the tidal propagation during the flood and causes the surface velocity to be smaller than the bottom velocity at mid-tide. Close to the bottom, velocities follow an anticlockwise movement due to the tidal propagation. At the water surface, velocities follow only an alternative movement of either ebb or flood, along the channel direction. No cross shore velocities can develop at the surface in the channel.

  3. Radiative Impacts of Elevated Aerosol Layers from Different Origins

    NASA Astrophysics Data System (ADS)

    Sauer, D. N.; Weinzierl, B.; Gasteiger, J.; Heimerl, K.

    2014-12-01

    Aerosol particles are omnipresent in the Earth's atmosphere and have important impacts on weather and climate by their effects on the atmospheric radiative balance. With the advent of more and more sophisticated representations of atmospheric processes in earth system models, the lack of reliable input data on aerosols leads to significant uncertainties in the prediction of future climate scenarios. In recent years large discrepancies in radiative forcing estimates from aerosol layers in modeling studies have been revealed emphasizing the need for detailed and systematic observations of aerosols. Airborne in-situ measurements represent an important pillar for validating both model results and retrievals of aerosol distributions and properties from remote sensing methods on global scales. However, detailed observations are challenging and therefore are subject to substantial uncertainties themselves. Here we use data from airborne in-situ measurements of elevated aerosol layers from various field experiments in different regions of the world. The data set includes Saharan mineral dust layers over Africa, the Atlantic Ocean and the Caribbean from the SALTRACE and the SAMUM campaigns as well as long-range transported biomass burning aerosol layers from wild fires in the Sahel region and North America measured over the tropical Atlantic Ocean, Europe and the Arctic detected during SAMUM2, CONCERT2011, DC3 and ACCESS 2012. We aim to characterize the effects of the measured aerosol layers, in particular with respect to ageing, mixing state and vertical structure, on the overall atmospheric radiation budget as well as local heating and cooling rates. We use radiative transfer simulations of short and long-wave radiation and aerosol optical properties derived in a consistent way from the in-situ observations of microphysical properties using T-matrix calculations. The results of this characterization will help to improve the parameterization of the effects of elevated

  4. Vertical structure of boundary layer convection during cold-air outbreaks at Barrow, Alaska

    NASA Astrophysics Data System (ADS)

    Wang, Yonggang; Geerts, Bart; Chen, Yaosheng

    2016-01-01

    Boundary layer convection (BLC) is common over high-latitude oceans and adjacent coastal regions when a cold airmass becomes exposed to a sufficient fetch of open water. The vertical structure of mixed-phase BLC clouds and precipitation is examined using the Atmospheric Radiation Measurement Program data set collected at the North Slope of Alaska (NSA) site at Barrow, Alaska. BLC may occur at this location in autumn, when cold air masses originating at higher latitudes advect southward over the still ice-free coastal waters north of Alaska. This study identifies such BLC and documents its occurrence and characteristics. Instruments used for this study include profiling Ka band radars, a depolarization backscatter profiling lidar, a scanning X band radar, a microwave radiometer, a ceilometer, surface meteorological probes, and radiosondes. Six criteria are applied to objectively identify the BLC events, using data collected between 2004 and 2013. BLC episodes are relatively common at the NSA site, but almost exclusively in the month of October, and most episodes are relatively short, less than 10 h in duration. Liquid water is commonly found in these mixed-phase BLC clouds, with a typical liquid water path of 150 g/m2, and snowfall rates average ~3 mm h-1 (water equivalent), in some cases over 10 mm h-1, notwithstanding the low cloud echo tops (~1.0-1.5 km). In one rather weak but persistent episode fall speed estimates derived from the profiling Ka band radar indicates the presence of rimed particles, confirming the convective nature of this precipitation.

  5. The Electrical Structure of Terrestrial Dust Devils: Implications of Multiple Vertical Measurements of the Electric Field

    NASA Astrophysics Data System (ADS)

    Delory, G. T.; Farrell, W. M.; Hillard, B.; Renno, N. O.; Smith, P.; Marshall, J. R.; Eatchel, A.

    2002-12-01

    In this work we discuss observations of the electrical structure of dust devils made in the summer of 2001 and 2002 during the Mars Atmosphere and Dust in the Optical and Radio (MATADOR) field campaign outside of Tucson, Arizona. While it has long been known that Terrestrial dust devils can support large electric fields of magnitudes of up to 10 kV/m or more, the fundamental features of the charging mechanism have yet to be fully characterized from an observational perspective. If triboelectric charging is indeed responsible for the generation of significant electric potentials within the dust column, some means of large scale stratification and/or separation of charges is necessary to maintain these fields. To help address this question and elucidate the overall vertical charge distribution of dust devils, we used two field mill instruments to make simultaneous measurements of electric fields both at the surface and 1 meter above the ground. At present, our observations indicate that the dust grains become negatively charged at or very near the air-surface interface. The largest devils recorded (30 m diameter) show a region of enhanced positive electric fields persisting for minutes after the event has passed, indicating the possible presence of a large scale collection of airborne positive charges following the negatively charged dust column. Based on our observations, the key to the charging mechanism appears to reside in the bottom of the saltation layer where the bulk of collisional frictional charging is likely to occur. We discuss the implications of these observations for theories of Terrestrial dust devil electrification and for our understanding of similar processes on Mars.

  6. Mesoscale eddies in the South Atlantic Bight and the Gulf Stream Recirculation region: Vertical structure

    NASA Astrophysics Data System (ADS)

    Castelao, Renato M.

    2014-03-01

    Sea level anomalies from altimeters are combined with decade-long potential temperature and salinity profiles from Argo floats to investigate the vertical structure of mesoscale eddies in the South Atlantic Bight (SAB) and the Gulf Stream Recirculation region. Eddy detection and eddy tracking algorithms are applied to the satellite observations, and hydrography profiles from floats that surfaced inside eddies are used to construct three-dimensional composites of cyclones and anticyclones. Eddies are characterized by large temperature and salinity anomalies at 500-1000 m depth and near the surface, and by small anomalies at 200-400 m below the surface at the depth of the North Atlantic Subtropical Mode Water. Anomalies associated with anticyclones are generally larger and found deeper in the water column compared to those due to the presence of cyclones. Geostrophic velocities around eddies generally exceed their translation speed in the top 1000 m of the water column. As such, these eddies can trap water in their interior as they propagate westward. Combining the volume of water inside eddies above their trapping depths with the number of eddies that propagate into the SAB each year, it is estimated that cyclones and anticyclones transport 3.5 ± 0.9 Sv and 4.1 ± 1.7 Sv onshore toward the Gulf Stream, respectively. The total volume transport of 7.6 ± 2.2 Sv represents an important fraction of previous estimates of the onshore transport in the Gulf Stream Recirculation gyre. Since eddies are characterized by large temperature and salinity anomalies, they also contribute significantly to the onshore transport of heat and salt.

  7. Vertical structure of Martian dust measured by solar infrared occultations from the PHOBOS spacecraft

    NASA Astrophysics Data System (ADS)

    Korablev, O. I.; Krasnopolsky, V. A.; Rodin, A. V.; Chassefiere, E.

    1993-03-01

    An extended analysis of IR occultation data of the Martian atmosphere from the Phobos spacecraft is presented. Altitude profiles of volume extinction coefficients at 1.9 and 3.7 microns are presented and the aerosol parameters including number density and effective radius are evaluated using the approximation of spherical dust particles and classical Mie theory. The data are interpreted using a dynamic model of the Martian atmosphere.

  8. Precursor wave structure, prereversal vertical drift, and their relative roles in the development of post sunset equatorial spread-F

    NASA Astrophysics Data System (ADS)

    Abdu, Mangalathayil; Sobral, José; alam Kherani, Esfhan; Batista, Inez S.; Souza, Jonas

    2016-07-01

    The characteristics of large-scale wave structure in the equatorial bottomside F region that are present during daytime as precursor to post sunset development of the spread F/plasma bubble irregularities are investigated in this paper. Digisonde data from three equatorial sites in Brazil (Fortaleza, Sao Luis and Cachimbo) for a period of few months at low to medium/high solar activity phases are analyzed. Small amplitude oscillations in the F layer true heights, representing wave structure in polarization electric field, are identified as upward propagating gravity waves having zonal scale of a few hundred kilometers. Their amplitudes undergo amplification towards sunset, and depending on the amplitude of the prereversal vertical drift (PRE) they may lead to post sunset generation of ESF/plasma bubble irregularities. On days of their larger amplitudes they appear to occur in phase coherence on all days, and correspondingly the PRE vertical drift velocities are larger than on days of the smaller amplitudes of the wave structure that appear at random phase on the different days. The sustenance of these precursor waves structures is supported by the relatively large ratio (approaching unity) of the F region-to- total field line integrated Pedersen conductivities as calculated using the SUPIM simulation of the low latitude ionosphere. This study examines the role of the wave structure relative to that of the prereversal vertical drift in the post sunset spread F irregularity development.

  9. Variation in Community Structure across Vertical Intertidal Stress Gradients: How Does It Compare with Horizontal Variation at Different Scales?

    PubMed Central

    Valdivia, Nelson; Scrosati, Ricardo A.; Molis, Markus; Knox, Amanda S.

    2011-01-01

    In rocky intertidal habitats, the pronounced increase in environmental stress from low to high elevations greatly affects community structure, that is, the combined measure of species identity and their relative abundance. Recent studies have shown that ecological variation also occurs along the coastline at a variety of spatial scales. Little is known, however, on how vertical variation compares with horizontal variation measured at increasing spatial scales (in terms of sampling interval). Because broad-scale processes can generate geographical patterns in community structure, we tested the hypothesis that vertical ecological variation is higher than fine-scale horizontal variation but lower than broad-scale horizontal variation. To test this prediction, we compared the variation in community structure across intertidal elevations on rocky shores of Helgoland Island with independent estimates of horizontal variation measured at the scale of patches (quadrats separated by 10s of cm), sites (quadrats separated by a few m), and shores (quadrats separated by 100s to 1000s of m). The multivariate analyses done on community structure supported our prediction. Specifically, vertical variation was significantly higher than patch- and site-scale horizontal variation but lower than shore-scale horizontal variation. Similar patterns were found for the variation in abundance of foundation taxa such as Fucus spp. and Mastocarpus stellatus, suggesting that the effects of these canopy-forming algae, known to function as ecosystem engineers, may explain part of the observed variability in community structure. Our findings suggest that broad-scale processes affecting species performance increase ecological variability relative to the pervasive fine-scale patchiness already described for marine coasts and the well known variation caused by vertical stress gradients. Our results also indicate that experimental research aiming to understand community structure on marine shores

  10. Observational study of formation mechanism, vertical structure, and dust emission of dust devils over the Taklimakan Desert, China

    NASA Astrophysics Data System (ADS)

    Liu, Chong; Zhao, Tianliang; Yang, Xinghua; Liu, Feng; Han, Yongxiang; Luan, Zhaopeng; He, Qing; Rood, Mark; Yuen, Wangki

    2016-04-01

    A field observation of dust devils was conducted at Xiaotang over the Taklimakan Desert (TD), China, from 7 to 14 July 2014. The measurements of dust devil opacity with the digital optical method and the observed atmospheric boundary layer conditions were applied to investigate the dust devils' formation mechanism, vertical structure, and dust emissions. The critical conditions in the atmospheric boundary layer for dust devil formation were revealed with the land-air surface temperature difference of higher than 15°C, the enhanced momentum flux and sensible heat flux up to 0.54 kg m-1 s-2 and 327 W m-2, respectively, the weak vertical wind shear with the low wind shear index α < 0.10, and the unstable stratification in the lower atmosphere. Based on observed dust opacities, it is identified that a typical dust devil was vertically structured with central updrafts and peripheral downdrafts of dust particles with the asymmetrically horizontal distribution of dust in a rotating dust column. The vertical flux of near-surface dust emissions was also estimated in a range from 5.4 × 10-5 to 9.6 × 10-5 kg m-2 s-1 for a typical dust devil event over TD.

  11. Satellite-Derived Aerosol Variability over China

    NASA Astrophysics Data System (ADS)

    de Leeuw, G.; Sogacheva, L.; Rodriguez, E.; Sofiev, M.; Vira, J.; Amiridis, V.; Marinou, E.; Kourtidis, K. A.; Georgoulias, A.; Xue, Y.; van der A, R.

    2015-12-01

    The main objective of the MarcoPolo project is to improve air quality monitoring, modelling and forecasting over China using satellite-retrieved observations of aerosols, NOx, SO2, and biogenic gases. This information will be used to derive emission estimates which will be used together with known information from the ground, to construct a new emission database for use with regional and local air quality models. In this contribution we report on the use of satellite data to obtain information on the occurrence of aerosols over China. Several different instruments, in particular MODIS and AATSR, are used to provide the spatial AOD since 2002 as well as a merged AOD product providing improved coverage. CALIOP is used to provide information on the vertical structure of aerosols, including aerosol type information. The AOD data sets are validated and evaluated versus sun photometer data from AERONET and the Chinese network CARSNET. This is particularly valuable because aerosol retrieval algorithms are developed and validated over areas where many independent ground-based observations are available, such as over the eastern USA and Europe. However, over these areas the AOD levels are generally much lower than over China, and the occurrence of such high AOD, combined with the variation in aerosol type and surface characteristics, poses particular problems as regards data selection and discrimination between high AOD and the occurrence of clouds. An initial analysis of the spatial and vertical variability of the AOD is provided and time series showing the variation over representative areas are presented, combining the various information sources indicated above. AOD time series will be compared with those from precursor gases and model estimates.

  12. HARLIE Aerosol and Cloud Structure and Wind Observations during HARGLO and IHOP

    NASA Technical Reports Server (NTRS)

    Schwemmer, Geary K.; Miller, David O.; Wilkersorf, Thomas D.

    2003-01-01

    The Holographic Airborne Rotating Lidar Instrument Experiment (HARLIE) is a conical-scanning, 1-micron wavelength lidar that has been adapted for ground-based applications and used to infer horizontal wind information by tracking the motions of aerosol and cloud scattering structures. In addition, HARLIE's rapid continuous scanning enables boundary layer statistics and a new cloud lidar data product that gives cloud coverage as a function of altitude with high temporal resolution. HARLIE has been used in several field campaigns while developing the techniques for wind, boundary layer (BL), and cloud data products. These campaigns involved a variety of wind measuring instruments including rawindsondes, cloud-tracked winds from video imagery, Doppler lidars and Doppler radars. HARGLO-2 was one of these campaigns and was dedicated to wind profile intercomparisons over a 1-week period in November of 2001. The most recent of these campaigns was the International H20 Project (IHOP) located in the Southern Great Plains of the US during May and June of 2002.

  13. Why the long face? The importance of vertical image structure for biological "barcodes" underlying face recognition.

    PubMed

    Spence, Morgan L; Storrs, Katherine R; Arnold, Derek H

    2014-07-29

    Humans are experts at face recognition. The mechanisms underlying this complex capacity are not fully understood. Recently, it has been proposed that face recognition is supported by a coarse-scale analysis of visual information contained in horizontal bands of contrast distributed along the vertical image axis-a biological facial "barcode" (Dakin & Watt, 2009). A critical prediction of the facial barcode hypothesis is that the distribution of image contrast along the vertical axis will be more important for face recognition than image distributions along the horizontal axis. Using a novel paradigm involving dynamic image distortions, a series of experiments are presented examining famous face recognition impairments from selectively disrupting image distributions along the vertical or horizontal image axes. Results show that disrupting the image distribution along the vertical image axis is more disruptive for recognition than matched distortions along the horizontal axis. Consistent with the facial barcode hypothesis, these results suggest that human face recognition relies disproportionately on appropriately scaled distributions of image contrast along the vertical image axis.

  14. Examining the vertical structure of clouds and precipitation for different cloud types in CAM5 using satellite data

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Klein, S. A.; Ma, H.; Boyle, J. S.; Caldwell, P.

    2013-12-01

    Climate models have difficulties in correctly simulating clouds and precipitation. It is critical to know the internal structure of clouds and precipitation since it is the vertical distribution of condensate that determines the characteristics of the cloud radiative forcing and lends insight into the vertical structure of condensation heating, which have large impact on the evolution of cloud systems. Cloudsat and CALIPSO provide the unprecedented data that allow us to look at detailed cloud and precipitation structures. In this study, the simulated radar reflectivities and lidar signals are compared to satellite observations, and the vertical structures of clouds and precipitation simulated in CAM5 are examined using case studies. Impact of precipitation distributions on the simulator output is explored. Our focus is to evaluate how well the model simulated clouds and precipitation over different important cloud regimes. The cases for different cloud types selected include deep convection in the ITCZ, extratropical frontal system, stratocumulus, trade cumulus, and mixed-phase cloud. This work was performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. This abstract is LLNL-ABS-641836.

  15. Orbiting lidar simulations. 1: Aerosol and cloud measurements by an independent-wavelength technique.

    PubMed

    Russell, P B; Morley, B M; Livingston, J M; Grams, G W; Patterson, E M

    1982-05-01

    Aerosol and cloud measurements are simulated for a space shuttle lidar. Expected errors (in signal, transmission, density, and calibration) are calculated algebraically and checked by simulating measurements and retrievals using random number generators. Vertical resolution is 0.1-0.5 km in the troposphere, 0.5-2.0 km above, except 0.25-1.0 km in mesospheric cloud and aerosol layers. Horizontal resolution is 100-2000 km. By day vertical structure is retrieved for tenuous clouds, Saharan aerosols, and boundary layer aerosols (at 0.53 and 1.06 microm) as well as strong volcanic stratospheric aerosols (at 0.53 microm). Quantitative backscatter is retrieved provided that particulate optical depth does not exceed approximately 0.3. By night all these constituents are retrieved plus upper tropospheric and stratospheric aerosols (at 1.06 microm), mesospheric aerosols (at 0.53 microm), and noctilucent clouds (at 1.06 and 0.53 microm). Molecular density is a leading source of error in measuring nonvolcanic stratospheric and upper tropospheric aerosols.

  16. Balloon-borne observations of the development and vertical structure of the Antarctic ozone hole in 1986

    NASA Technical Reports Server (NTRS)

    Hofmann, D. J.; Harder, J. W.; Rolf, S. R.; Rosen, J. M.

    1987-01-01

    The vertical distribution of ozone measured at McMurdo Station, Antarctica using balloon-borne sensors on 33 occasions during November 6, 1986 - August 25, 1986 is described. These observations suggest a highly structured cavity confined to the 12-20 km altitude region. In the 17-19 km altitude range, the ozone volume mixing ratio declined from about 2 ppm at the end of August to about 0.5 ppm by mid-October. The average decay in this region can be described as exponential with a half life of about 25 days. While total ozone, as obtained from profile integration, declined only about 35 percent, the integrated ozone between 14 and 18 km declined more than 70 percent. Vertical ozone profiles in the vortex revealed unusual structure with major features from 1 to 5 km thick which had suffered ozone depletions as great as 90 percent.

  17. Structures of the Jovian Upper Clouds and the Scattering Properties of Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Itoh, S.; Satoh, T.; Kawabata, K.

    1999-09-01

    The single scattering phase functions of Jovian aerosols, obtained by analyzing the Pioneer photometry data (Tomasko et al., Icarus 33, 558, 1978), have been widely used to investigate Jupiter's upper cloud structures. These were constructed for the blue (440 nm) and the red (640 nm), while the recent high-resolution observations extend to longer wavelengths. Since the light scattering is a function of wavelength, simply adopting the Pioneer phase functions for the longer-wavelength data could introduce systematic errors to the resulting atmospheric structures. The Pioneer phase functions are represented by a two-term Henyey-Greenstein function which carries no wavelength-dependent information. To obtain that, we therefore approximate the Pioneer phase functions using Mie scattering by spherical particles. Two sets of size distribution parameters (one for the bright zone and the other for the dark belt) and two values of refractive index (one for the blue and the other for the red) are optimized by means of the generalized data inversion technique based on the singular-value decomposition. Sufficiently good approximation is obtained if the real part of the refractive index is allowed to increase to approximately 1.5, slightly larger than the nominal value for the ammonia ice. Although no appropriate account for such a high value can be established at this stage, the effects due to non-sphericity of the ice crystals are likely to be responsible for this. Next, we perform multiple scattering model analyses of a collection of photometry data, coverring a wide wavelength range from 220 nm to 950 nm (West, Icarus 38, 12, 1979; Tomasko et al., Icarus 65, 218, 1986; Kuehn and Beebe, Icarus 101, 282, 1993). The optical depth of the haze layer based on our analyses shows a wavelength dependence which is rather consistent with the assumption that the haze particles may also be of non-spherical shape: it decreases quite rapidly as we go toward the near-infrared wavelength.

  18. Circulation, heat exchange and vertical structure of the Hornsund - the Svalbard Archipelago fiord.

    NASA Astrophysics Data System (ADS)

    Jakacki, Jaromir; Przyborska, Anna; Kosecki, Szymon; Sundfjord, Arild

    2015-04-01

    The Hornsund fjord is located in the southwestern part of Spitsbergen- the biggest island of the Svalbard Archipelago. The fjord is influenced by two major currents in this area. The first one is the current carrying the cold and less saline waters around the southern Spitsbergen tip, often called the Sørkapp Current or the South Cape Current. The second is the well-known West Spitsbergen Current (WSC), carrying salty and warm Atlantic Waters through Fram Strait into the Arctic Ocean. From a biological point of view, Hornsund can be treated as a young unstable system or cold system, which suggests that it is under an influence of the South Cape Current. Because of limited measurements in this area, the hydrodynamic model MIKE3D has been implemented for this fjord to diagnose which current has the main influence on Hornsund. The fjord domain was extended into the shelf area. At the lateral boundary of the extended domain, data from the ROMS simulation of the Svalbard area made by the Norwegian Institute of Marine Research (IMR) with resolution of 800 m have been used. Atmospheric data from European Centre for Medium Weather Forecast (ECMWF) were employed as well as from the Global Data Assimilation System (GDAS, 1 and 0.5 degrees) reanalysis that uses metrological data from Polish Polar Station located in Hornsund. Based on 5 years of simulation (2005-2010) seasonal and annual general circulation in the fjord has been described. Estimation of the heat transport between fjord and ocean, and between fjord and atmosphere will permit to establish the heat budget and help to evaluate the influence of the South Cape Current and WSC on the fjord ecosystem development. An influence of the fresh water fluxes and vertical structure of water masses and their transformations will be also discussed. This work was partially performed in the frame of the projects GAME (DEC-2012/04/A/NZ8/00661) and AWAKE2 (Pol-Nor/198675/17/2013)

  19. Atmospheric Chemistry: Nature's plasticized aerosols

    NASA Astrophysics Data System (ADS)

    Ziemann, Paul J.

    2016-01-01

    The structure of atmospheric aerosol particles affects their reactivity and growth rates. Measurements of aerosol properties over the Amazon rainforest indicate that organic particles above tropical rainforests are simple liquid drops.

  20. Comparing the Cloud Vertical Structure Derived from Several Methods Based on Radiosonde Profiles and Ground-based Remote Sensing Measurements

    SciTech Connect

    Costa-Suros, M.; Calbo, J.; Gonzalez, J. A.; Long, Charles N.

    2014-08-27

    The cloud vertical distribution and especially the cloud base height, which is linked to cloud type, is an important characteristic in order to describe the impact of clouds in a changing climate. In this work several methods to estimate the cloud vertical structure (CVS) based on atmospheric sounding profiles are compared, considering number and position of cloud layers, with a ground based system which is taken as a reference: the Active Remote Sensing of Clouds (ARSCL). All methods establish some conditions on the relative humidity, and differ on the use of other variables, the thresholds applied, or the vertical resolution of the profile. In this study these methods are applied to 125 radiosonde profiles acquired at the ARM Southern Great Plains site during all seasons of year 2009 and endorsed by GOES images, to confirm that the cloudiness conditions are homogeneous enough across their trajectory. The overall agreement for the methods ranges between 44-88%; four methods produce total agreements around 85%. Further tests and improvements are applied on one of these methods. In addition, we attempt to make this method suitable for low resolution vertical profiles, which could be useful in atmospheric modeling. The total agreement, even when using low resolution profiles, can be improved up to 91% if the thresholds for a moist layer to become a cloud layer are modified to minimize false negatives with the current data set, thus improving overall agreement.

  1. Vertical structure of the wind field during the Special Observing Period I of the Global Weather Experiment

    NASA Technical Reports Server (NTRS)

    Paegle, J. N.; Paegle, J.; Zhen, Z.; Sampson, G.

    1986-01-01

    The vertical structure of the global atmosphere is analyzed for selected periods of the Special Observing Period I (SOP-I) for the Global Weather Experiment (GWE). The analysis consists of projection of the stream-function and velocity potential at 200 and 850 mb on spherical harmonics and of the wind and height fields on the normal modes of a linearized form of the primitive equations for a basic state at rest. The kinematic vertical structure is discussed in terms of correlation coefficients of the 200 mb and 850 mb winds and analysis of the internal and external normal modes of the primitive equations. The reliability of the results is checked by applying the same analysis methods to data sets obtained from three different institutions: Geophysical Fluid Dynamics Laboratory (GFDL), European Center for Medium Range Weather Forecasting (ECMWF), and Goddard Laboratory for the Atmospheres (GLA). It is found that, on a global basis, vertically reversing circulations are as important as the equivalent barotropic structures. For the verticaly reversing components, the gravity and mixed Rossby-gravity modes have contributions of the same order of magnitude as those of the Rossby modes in tropical latitudes.

  2. Vertical Cloud Structure Of The 2009 Jupiter Impact Based On HST/WFC3 Observations

    NASA Astrophysics Data System (ADS)

    Perez-Hoyos, Santiago; Sanz-Requena, J. F.; Sanchez-Lavega, A.; Wong, M.; Hueso, R.; Hammel, H. B.; Orton, G. S.; Fletcher, L. N.; de Pater, I.; Simon-Miller, A. A.; Clarke, J. T.; Noll, K.; Yanamandra-Fisher, P. A.

    2010-10-01

    The impact of a body of unknown origin with Jupiter in July 2009 (Sánchez-Lavega et al., Astrophys. J. Lett, Vol. 715, L155. 2010) produced an intense perturbation of the planet's atmosphere at the visible levels. The perturbation was caused by dense aerosol material; this strongly absorbing material expanded steadily as it was advected by the local winds. This phenomenon was observed at high spatial resolution by the Hubble Space Telescope in July, August, September and November 2009 with recently installed Wide Field Camera 3. In this work, we present radiative transfer modeling of the observed reflectivity in the near UV (200nm) to near IR (950nm) range. The geometrical and spectral variations of reflectivity elucidate the main particle properties (optical thickness, size, imaginary refractive index) and their temporal evolution. The aerosol particles that formed during the impact have a mean radius of about 1 micron and are located high in the atmosphere (above 10 mbar), in good agreement ith ground-based observations in deep methane absorption bands in the near infrared. The density of this particle layer decreases with time until it approaches that of the pre-impact atmosphere. These results are also discussed in terms of what we know from other impacts in Jupiter (1994's SL9 event and 2010's bolide). Acknowledgements: SPH, ASL and RH are supported by the Spanish MICIIN AYA2009-10701 with FEDER and Grupos Gobierno Vasco IT-464-07.

  3. The Role of Boundary Layer Aerosol in the Vertical Development of Precipitation and Electrification: Another Look at the Contrast Between Lightning over Land and Over Ocean

    NASA Technical Reports Server (NTRS)

    Williams, E.; Rosenfeld, D.; Madden, N.; Labrada, C.; Gerlach, J.; Atkinson, L.

    1999-01-01

    Comparisons are made between the cloud condensation nuclei (CCN) concentration in the boundary layer and radar/electrical observations of the vertical development of precipitation and lightning in both the 'break period' and 'monsoon' regimes in tropical Brazil. The initial radar echoes and the maximum flash rates are found to be higher when the CCN concentration is higher, characteristic of the 'break period' conditions. One possible explanation for both observations is the survival of cloud droplets against coalescence and their attainment of the mixed phase region aloft.

  4. Lidar Investigation of Aerosol Pollution Distribution near a Coal Power Plant

    NASA Technical Reports Server (NTRS)

    Mitsev, TS.; Kolarov, G.

    1992-01-01

    Using aerosol lidars with high spatial and temporal resolution with the possibility of real-time data interpretation can solve a large number of ecological problems related to the aerosol-field distribution and variation and the structure of convective flows. Significantly less expensive specialized lidars are used in studying anthropogenic aerosols in the planetary boundary layer. Here, we present results of lidar measurements of the mass-concentration field around a coal-fired power plant with intensive local aerosol sources. We studied the pollution evolution as a function of the emission dynamics and the presence of retaining layers. The technique used incorporates complex analysis of three types of lidar mapping: horizontal map of the aerosol field, vertical cross-section map, and a series of profiles along a selected path. The lidar-sounding cycle was performed for the time of atmosphere's quasi-stationarity.

  5. Moist convection - A mechanism for producing the vertical structure of the Jovian equatorial plumes

    NASA Astrophysics Data System (ADS)

    Stoker, C. R.

    1986-07-01

    Possible roles are explored for moist convection in the production of bright plume features in the Jupiter atmosphere. The features have been observed at least since 1881. A one-dimensional model is developed for a Jovian cloud and the conditions necessary for convection to occur on Jupiter are defined. The model is used to predict the vertical velocity and maximum altitude of moist clouds that are convected over a vertical extent of 100, 10 and 1 km. Convection within the ammonia layer would not produce sufficient buoyancy to sublime from the rising air parcel. Water rising from the 5 bar to 1 bar level could carry enough ammonia to the cooler region to form plume anvils in the stable layer above 700 mbar. If unpolluted during the convection, the water could be the source of high altitude haze above the entire equatorial zone.

  6. Ultra-low-frequency vertical vibration isolator based on a two-stage beam structure for absolute gravimetry

    NASA Astrophysics Data System (ADS)

    Wang, G.; Wu, K.; Hu, H.; Li, G.; Wang, L. J.

    2016-10-01

    To reduce seismic and environmental vibration noise, ultra-low-frequency vertical vibration isolation systems play an important role in absolute gravimetry. For this purpose, an isolator based on a two-stage beam structure is proposed and demonstrated. The isolator has a simpler and more robust structure than the present ultra-low-frequency vertical active vibration isolators. In the system, two beams are connected to a frame using flexural pivots. The upper beam is suspended from the frame with a normal hex spring and the lower beam is suspended from the upper one using a zero-length spring. The pivot of the upper beam is not vertically above the pivot of the lower beam. With this special design, the attachment points of the zero-length spring to the beams can be moved to adjust the effective stiffness. A photoelectric detector is used to detect the angle between the two beams, and a voice coil actuator attached to the upper beam is controlled by a feedback circuit to keep the angle at a fixed value. The system can achieve a natural period of 100 s by carefully moving the attachment points of the zero-length spring to the beams and tuning the feedback parameters. The system has been used as an inertial reference in the T-1 absolute gravimeter. The experiment results demonstrate that the system has significant vibration isolation performance that holds promise in applications such as absolute gravimeters.

  7. Self-assembled InAs quantum dots within a vertical cavity structure for all-optical switching devices

    NASA Astrophysics Data System (ADS)

    Jin, C. Y.; Kojima, O.; Inoue, T.; Kita, T.; Wada, O.; Hopkinson, M.; Akahane, K.

    2010-02-01

    An all-optical switching device has been proposed by using self-assembled InAs/GaAs quantum dots (QDs) within a vertical cavity structure for ultrafast optical communications. This device has several desirable properties, such as the ultra-low power consumption, the micrometre size, and the polarization insensitive operation. Due to the threedimensional confined carrier state and the broad size distribution of self-assembled InAs/GaAs QDs, it is crucial to enhance the interaction between QDs and the cavity with appropriately designed 1D periodic structure. Significant QD/cavity nonlinearity is theoretically observed by increasing the GaAs/AlAs pair number of the bottom mirror. By this consideration, we have fabricated vertical-reflection type QD switches with 12 periods of GaAs/Al0.8Ga0.2As for the top mirror and 25 periods for the bottom mirror to give an asymmetric vertical cavity. Optical switching via the QD excited state exhibits a fast switching process with a time constant down to 23 ps, confirming that the fast intersubband relaxation of carriers inside QDs is an effective means to speed up the switching process. A technique by changing the light incident angle realizes wavelength tunability over 30 nm for the QD/cavity switch.

  8. Structure and Characterization of Vertically Aligned Single-Walled Carbon Nanotube Bundles

    DOE PAGES

    Márquez, Francisco; López, Vicente; Morant, Carmen; Roque-Malherbe, Rolando; Domingo, Concepción; Elizalde, Eduardo; Zamora, Félix

    2010-01-01

    Arrmore » ays of vertically aligned single-walled carbon nanotube bundles, SWCNTs, have been synthesized by simple alcohol catalytic chemical vapor deposition process, carried out at 800°C. The formed SWCNTs are organized in small groups perpendicularly aligned and attached to the substrate. These small bundles show a constant diameter of ca. 30 nm and are formed by the adhesion of no more than twenty individual SWCNTs perfectly aligned along their length.« less

  9. Principal component structure and sport-specific differences in the running one-leg vertical jump.

    PubMed

    Laffaye, G; Bardy, B G; Durey, A

    2007-05-01

    The aim of this study is to identify the kinetic principal components involved in one-leg running vertical jumps, as well as the potential differences between specialists from different sports. The sample was composed of 25 regional skilled athletes who play different jumping sports (volleyball players, handball players, basketball players, high jumpers and novices), who performed a running one-leg jump. A principal component analysis was performed on the data obtained from the 200 tested jumps in order to identify the principal components summarizing the six variables extracted from the force-time curve. Two principal components including six variables accounted for 78 % of the variance in jump height. Running one-leg vertical jump performance was predicted by a temporal component (that brings together impulse time, eccentric time and vertical displacement of the center of mass) and a force component (who brings together relative peak of force and power, and rate of force development). A comparison made among athletes revealed a temporal-prevailing profile for volleyball players, and a force-dominant profile for Fosbury high jumpers. Novices showed an ineffective utilization of the force component, while handball and basketball players showed heterogeneous and neutral component profiles. Participants will use a jumping strategy in which variables related to either the magnitude or timing of force production will be closely coupled; athletes from different sporting backgrounds will use a jumping strategy that reflects the inherent demands of their chosen sport.

  10. A continuous flow micro filtration device for plasma/blood separation using submicron vertical pillar gap structures

    NASA Astrophysics Data System (ADS)

    Kang, Tae Goo; Yoon, Yong-Jin; Ji, Hongmiao; Lim, Pei Yi; Chen, Yu

    2014-08-01

    This work demonstrates a continuous flow plasma/blood separator using a vertical submicron pillar gap structure. The working principle of the proposed separator is based on size exclusion of cells through cross-flow filtration, in which only plasma is allowed to pass through submicron vertical pillars located tangential to the main flow path of the blood sample. The maximum filtration efficiency of 99.9% was recorded with a plasma collection rate of 0.67 µl min-1 for an input blood flow rate of 12.5 µl min-1. The hemolysis phenomenon was observed for an input blood flow rate above 30 µl min-1. Based on the experimental results, we can conclude that the proposed device shows potential for the application of on-chip plasma/blood separation as a part of integrated point-of-care (POC) diagnostics systems.

  11. Aerosol measurements in the IR: from limb to nadir?

    NASA Technical Reports Server (NTRS)

    Eldering, A.; Irion, F. W.; Mills, F. P.; Steele, H. M.; Gunson, M. R.

    2001-01-01

    Vertical profiles of aerosol concentration have been derived from the ATMOS solar occultation dataset. The EOS instrument TES has motivated studies of the feasibility of quantifying aerosols in nadir and limb emission measurements.

  12. Assessing Vertical Distribution of Trace Species as related to Transport and Emissions

    NASA Astrophysics Data System (ADS)

    Chen, G.; Shook, M.; Scarino, A. J.; Silverman, M. L.; Kleb, M. M.; Crawford, J. H.

    2014-12-01

    The NASA DISCOVER-AQ (Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality) field campaign conducted extensive vertical sampling of traces gases and aerosols during four separate deployments: Baltimore, MD (2011); California Central Valley (2013); Houston, TX (2013); and Denver, CO (2014). The campaign's primary objective is to better understand how column measurements can be used to infer surface conditions. In order to achieve this objective, it is necessary to understand the factors that control the vertical distribution of trace species that are highly relevant to air quality issues. Leveraging the over 400 vertical profiles from the Baltimore and Houston deployments, we will contrast the DISCOVER-AQ vertical observations of CO2, CO, O3, NOx, CH2O, and aerosol properties from these coastal regions. After determining airmass origin and atmospheric vertical structure for each of the profiles, the vertical structure of these trace species will be compared to assess the impact and relative importance of vertical transport, advection, and local emissions.

  13. Aerosol based direct-write micro-additive fabrication method for sub-mm 3D metal-dielectric structures

    NASA Astrophysics Data System (ADS)

    Rahman, Taibur; Renaud, Luke; Heo, Deuk; Renn, Michael; Panat, Rahul

    2015-10-01

    The fabrication of 3D metal-dielectric structures at sub-mm length scale is highly important in order to realize low-loss passives and GHz wavelength antennas with applications in wearable and Internet-of-Things (IoT) devices. The inherent 2D nature of lithographic processes severely limits the available manufacturing routes to fabricate 3D structures. Further, the lithographic processes are subtractive and require the use of environmentally harmful chemicals. In this letter, we demonstrate an additive manufacturing method to fabricate 3D metal-dielectric structures at sub-mm length scale. A UV curable dielectric is dispensed from an Aerosol Jet system at 10-100 µm length scale and instantaneously cured to build complex 3D shapes at a length scale  <1 mm. A metal nanoparticle ink is then dispensed over the 3D dielectric using a combination of jetting action and tilted dispense head, also using the Aerosol Jet technique and at a length scale 10-100 µm, followed by the nanoparticle sintering. Simulation studies are carried out to demonstrate the feasibility of using such structures as mm-wave antennas. The manufacturing method described in this letter opens up the possibility of fabricating an entirely new class of custom-shaped 3D structures at a sub-mm length scale with potential applications in 3D antennas and passives.

  14. Effects Of Vertical Wind Shear On Intensity And Structure Of Tropical Cyclone

    NASA Astrophysics Data System (ADS)

    Chen, Q.

    2014-12-01

    In this study, the effect of vertical wind shear (VWS) on the intensification of tropical cyclone (TC) is investigated via the numerical simulations. Results indicate that weak shear tends to facilitate the development of TC while strong shear appears to inhibit the intensification of TC. As the VWS is imposed on the TC, the vortex of the cyclone tends to tilt vertically and significantly in the upper troposphere. Consequently, the upward motion is considerably enhanced in the downshear side of the storm center and correspondingly, the low- to mid-level potential temperature decreases under the effect of adiabatic cooling, which leads to the increase of the low- to mid-level static instability and relative humidity and then facilitates the burst of convection. In the case of weak shear, the vertical tilting of the vortex is weak and the increase of ascent, static instability and relative humidity occur in the area close to the TC center. Therefore, active convection happens in the TC center region and facilitates the enhancement of vorticity in the inner core region and then the intensification of TC. In contrast, due to strong VWS, the increase of the ascent, static instability and relative humidity induced by the vertical tilting mainly appear in the outer region of TC in the case with stronger shear, and the convection in the inner-core area of TC is rather weak and convective activity mainly happens in the outer-region of the TC. Therefore, the development of a warm core is inhibited and then the intensification of TC is delayed. The numerical result shows that the tropical storm can still experience rapid intensification and finally develop into a strong tropical cyclone after a relatively long period of adjustment in the strong VWS environment. It is found that the convection plays an important role in the adjusting period. On one hand, the convection leads to the horizontal convergence of the low-level vorticity flux and therefore leads to the enhancement of

  15. 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.

    PubMed

    Sun, Yele; Du, Wei; Wang, Qingqing; Zhang, Qi; Chen, Chen; Chen, Yong; Chen, Zhenyi; Fu, Pingqing; Wang, Zifa; Gao, Zhiqiu; Worsnop, Douglas R

    2015-10-01

    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.

  16. 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.

    PubMed

    Sun, Yele; Du, Wei; Wang, Qingqing; Zhang, Qi; Chen, Chen; Chen, Yong; Chen, Zhenyi; Fu, Pingqing; Wang, Zifa; Gao, Zhiqiu; Worsnop, Douglas R

    2015-10-01

    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. PMID:26348650

  17. Energy band structure tailoring of vertically aligned InAs/GaAsSb quantum dot structure for intermediate-band solar cell application by thermal annealing process.

    PubMed

    Liu, Wei-Sheng; Chu, Ting-Fu; Huang, Tien-Hao

    2014-12-15

    This study presents an band-alignment tailoring of a vertically aligned InAs/GaAs(Sb) quantum dot (QD) structure and the extension of the carrier lifetime therein by rapid thermal annealing (RTA). Arrhenius analysis indicates a larger activation energy and thermal stability that results from the suppression of In-Ga intermixing and preservation of the QD heterostructure in an annealed vertically aligned InAs/GaAsSb QD structure. Power-dependent and time-resolved photoluminescence were utilized to demonstrate the extended carrier lifetime from 4.7 to 9.4 ns and elucidate the mechanisms of the antimony aggregation resulting in a band-alignment tailoring from straddling to staggered gap after the RTA process. The significant extension in the carrier lifetime of the columnar InAs/GaAsSb dot structure make the great potential in improving QD intermediate-band solar cell application.

  18. Analysis of the origin of peak aerosol optical depth in springtime over the Gulf of Tonkin.

    PubMed

    Shan, Xiaoli; Xu, Jun; Li, Yixue; Han, Feng; Du, Xiaohui; Mao, Jingying; Chen, Yunbo; He, Youjiang; Meng, Fan; Dai, Xuezhi

    2016-02-01

    By aggregating MODIS (moderate-resolution imaging spectroradiometer) AOD (aerosol optical depth) and OMI (ozone monitoring instrument) UVAI (ultra violet aerosol index) datasets over 2010-2014, it was found that peak aerosol loading in seasonal variation occurred annually in spring over the Gulf of Tonkin (17-23 °N, 105-110 °E). The vertical structure of the aerosol extinction coefficient retrieved from the spaceborne lidar CALIOP (cloud-aerosol lidar with orthogonal polarization) showed that the springtime peak AOD could be attributed to an abrupt increase in aerosol loading between altitudes of 2 and 5 km. In contrast, aerosol loading in the low atmosphere (below 1 km) was only half of that in winter. Wind fields in the low and high atmosphere exhibited opposite transportation patterns in spring over the Gulf of Tonkin, implying different sources for each level. By comparing the emission inventory of anthropogenic sources with biomass burning, and analyzing the seasonal variation of the vertical structure of aerosols over the Northern Indo-China Peninsula (NIC), it was concluded that biomass burning emissions contributed to high aerosol loading in spring. The relatively high topography and the high surface temperature in spring made planetary boundary layer height greater than 3 km over NIC. In addition, small-scale cumulus convection frequently occurred, facilitating pollutant rising to over 3 km, which was a height favoring long-range transport. Thus, pollutants emitted from biomass burning over NIC in spring were raised to the high atmosphere, then experienced long-range transport, leading to the increase in aerosol loading at high altitudes over the Gulf of Tonkin during spring. PMID:26969552

  19. Analysis of the origin of peak aerosol optical depth in springtime over the Gulf of Tonkin.

    PubMed

    Shan, Xiaoli; Xu, Jun; Li, Yixue; Han, Feng; Du, Xiaohui; Mao, Jingying; Chen, Yunbo; He, Youjiang; Meng, Fan; Dai, Xuezhi

    2016-02-01

    By aggregating MODIS (moderate-resolution imaging spectroradiometer) AOD (aerosol optical depth) and OMI (ozone monitoring instrument) UVAI (ultra violet aerosol index) datasets over 2010-2014, it was found that peak aerosol loading in seasonal variation occurred annually in spring over the Gulf of Tonkin (17-23 °N, 105-110 °E). The vertical structure of the aerosol extinction coefficient retrieved from the spaceborne lidar CALIOP (cloud-aerosol lidar with orthogonal polarization) showed that the springtime peak AOD could be attributed to an abrupt increase in aerosol loading between altitudes of 2 and 5 km. In contrast, aerosol loading in the low atmosphere (below 1 km) was only half of that in winter. Wind fields in the low and high atmosphere exhibited opposite transportation patterns in spring over the Gulf of Tonkin, implying different sources for each level. By comparing the emission inventory of anthropogenic sources with biomass burning, and analyzing the seasonal variation of the vertical structure of aerosols over the Northern Indo-China Peninsula (NIC), it was concluded that biomass burning emissions contributed to high aerosol loading in spring. The relatively high topography and the high surface temperature in spring made planetary boundary layer height greater than 3 km over NIC. In addition, small-scale cumulus convection frequently occurred, facilitating pollutant rising to over 3 km, which was a height favoring long-range transport. Thus, pollutants emitted from biomass burning over NIC in spring were raised to the high atmosphere, then experienced long-range transport, leading to the increase in aerosol loading at high altitudes over the Gulf of Tonkin during spring.

  20. Vertical waveguide structure optical printed circuit board based on a low-dielectric and transparent PCB materials

    NASA Astrophysics Data System (ADS)

    Hwang, Sung Hwan; Lee, Woo-Jin; An, Jong Bae; Kim, Gye Won; Kim, Myoung Jin; Jung, Eun Joo; Kim, Young Ho; Jung, Ki Young; Sohn, Ik-Bu; Rho, Byung Sup

    2015-02-01

    This paper suggests an optical printed circuit board (OPCB) having new optical coupling structures, including a laser-drilled and under-filled structure (LD-UFS) and a vertical waveguide structure (VWS). The suggested OPCB has the features of high-speed data transmission as well as highly efficient optical coupling because it was fabricated with low-dielectric and transparent electrical PCB materials through a PCB compatible process. To evaluate and compare the optical and electrical performances of the suggested OPCB with those of other OPCBs, the various types of OPCBs were fabricated and measured. The optical coupling losses of the LD-UFS and the VWS were measured with excellent results of 9.8 and 7.8 dB, respectively, which are lower than that of the basic structure. The electrical 3-dB bandwidth of the OPCB was also evaluated up to more than 40 GHz.

  1. Nitrogen addition and harvest frequency rather than initial plant species composition determine vertical structure and light interception in grasslands.

    PubMed

    Petersen, Ute; Isselstein, Johannes

    2015-01-01

    In biodiversity experiments based on seeded experimental communities, species richness and species composition exert a strong influence on canopy structure and can lead to an improved use of aboveground resources. In this study, we want to explore whether these findings are applicable to agriculturally managed permanent grassland. Vertical layered profiles of biomass, leaf area (LA) and light intensity were measured in a removal-type biodiversity experiment (GrassMan) to compare the canopy structure in grassland vegetation of different plant species composition (called sward types). Additionally, the altered sward types were subjected to four different management regimes by a combination of the factors fertilization (unfertilized, NPK fertilized) and cutting frequency (one late cut or three cuts). In spite of large compositional differences (ratio grasses : non-leguminous forbs : leguminous forbs ranging from 93 : 7 : 0 to 39 : 52 : 9), the vegetation of the same management regime hardly differed in its canopy structure, whereas the different management regimes led to distinct vertical profiles in the vegetation. However, the allocation of biomass in response to cutting and fertilization differed among the sward types. Vegetation dominated by grasses was denser and had more LA when fertilized compared with vegetation rich in dicots which merely grew taller. In functionally more diverse vegetation, light interception was not increased compared with vegetation consisting of more than 90 % of grasses in terms of biomass. Management had a much stronger influence on structure and light interception than plant species composition in this grassland experiment. PMID:26199402

  2. VERTICAL STRUCTURE OF A SUPERNOVA-DRIVEN TURBULENT, MAGNETIZED INTERSTELLAR MEDIUM

    SciTech Connect

    Hill, Alex S.; Matthew Haffner, L.; Ryan Joung, M.; Mac Low, Mordecai-Mark; Benjamin, Robert A.; Klingenberg, Christian; Waagan, Knut

    2012-05-10

    Stellar feedback drives the circulation of matter from the disk to the halo of galaxies. We perform three-dimensional magnetohydrodynamic simulations of a vertical column of the interstellar medium with initial conditions typical of the solar circle in which supernovae drive turbulence and determine the vertical stratification of the medium. The simulations were run using a stable, positivity-preserving scheme for ideal MHD implemented in the FLASH code. We find that the majority ( Almost-Equal-To 90%) of the mass is contained in thermally stable temperature regimes of cold molecular and atomic gas at T < 200 K or warm atomic and ionized gas at 5000 K < T < 10{sup 4.2} K, with strong peaks in probability distribution functions of temperature in both the cold and warm regimes. The 200-10{sup 4.2} K gas fills 50%-60% of the volume near the plane, with hotter gas associated with supernova remnants (30%-40%) and cold clouds (<10%) embedded within. At |z| {approx} 1-2 kpc, transition-temperature (10{sup 5} K) gas accounts for most of the mass and volume, while hot gas dominates at |z| > 3 kpc. The magnetic field in our models has no significant impact on the scale heights of gas in each temperature regime; the magnetic tension force is approximately equal to and opposite the magnetic pressure, so the addition of the field does not significantly affect the vertical support of the gas. The addition of a magnetic field does reduce the fraction of gas in the cold (<200 K) regime with a corresponding increase in the fraction of warm ({approx}10{sup 4} K) gas. However, our models lack rotational shear and thus have no large-scale dynamo, which reduces the role of the field in the models compared to reality. The supernovae drive oscillations in the vertical distribution of halo gas, with the period of the oscillations ranging from Almost-Equal-To 30 Myr in the T < 200 K gas to {approx}100 Myr in the 10{sup 6} K gas, in line with predictions by Walters and Cox.

  3. The Vertical Stellar Structure of the Milky Way: Introducing GLIMPSE 3D

    NASA Astrophysics Data System (ADS)

    Benjamin, Robert A.; GLIMPSE Team

    2007-12-01

    We present initial results from the Spitzer Legacy Project GLIMPSE 3D, a program to extend Spitzer/IRAC coverage of the Galactic plane from the midplane up to Galactic latitudes of |b|=4 degrees in the inner Galaxy (l? degrees). We present mid-infrared starcount maps of the Galactic disk and bulge and characterize the vertical stellar scaleheight as a function of longitude. We discuss how this data will be useful for characterzing the secular evolution of the stellar bar(s) of the Galaxy.

  4. Self-assembly of gold nanorods into vertically aligned, rectangular microplates with a supercrystalline structure

    NASA Astrophysics Data System (ADS)

    Xiao, Junyan; Li, Zhe; Ye, Xiaozhou; Ma, Yurong; Qi, Limin

    2013-12-01

    Vertically aligned, supercrystalline microplates with a well-defined rectangular shape were fabricated in a large area through self-assembly of gold nanorods by a novel bulk solution evaporation method. This evaporative self-assembly strategy involving continuous movement of the contact line can prevent the coffee-ring effect, thus allowing uniform deposition of discrete GNR superstructures over a large area and favoring the formation of GNR supercrystals with geometrically symmetric shapes. A mechanism based on the continuing nucleation and growth of smectic GNR superstructures accompanying the movement of the contact line was put forward for the formation of the unique GNR supercrystal arrays. Based on this mechanism, a micropatterned substrate was designed to control the nucleation location and growth direction, leading to the spontaneous self-assembly of nearly parallel arrays of vertically aligned, supercrystalline microplates of GNRs. The obtained rectangular-plate-shaped GNR supercrystals exhibited interesting anisotropic optical reflection properties, which were revealed by polarized light microscopy.Vertically aligned, supercrystalline microplates with a well-defined rectangular shape were fabricated in a large area through self-assembly of gold nanorods by a novel bulk solution evaporation method. This evaporative self-assembly strategy involving continuous movement of the contact line can prevent the coffee-ring effect, thus allowing uniform deposition of discrete GNR superstructures over a large area and favoring the formation of GNR supercrystals with geometrically symmetric shapes. A mechanism based on the continuing nucleation and growth of smectic GNR superstructures accompanying the movement of the contact line was put forward for the formation of the unique GNR supercrystal arrays. Based on this mechanism, a micropatterned substrate was designed to control the nucleation location and growth direction, leading to the spontaneous self-assembly of

  5. A passive microwave technique for estimating rainfall and vertical structure information from space. Part 1: Algorithm description

    NASA Technical Reports Server (NTRS)

    Kummerow, Christian; Giglio, Louis

    1994-01-01

    This paper describes a multichannel physical approach for retrieving rainfall and vertical structure information from satellite-based passive microwave observations. The algorithm makes use of statistical inversion techniques based upon theoretically calculated relations between rainfall rates and brightness temperatures. Potential errors introduced into the theoretical calculations by the unknown vertical distribution of hydrometeors are overcome by explicity accounting for diverse hydrometeor profiles. This is accomplished by allowing for a number of different vertical distributions in the theoretical brightness temperature calculations and requiring consistency between the observed and calculated brightness temperatures. This paper will focus primarily on the theoretical aspects of the retrieval algorithm, which includes a procedure used to account for inhomogeneities of the rainfall within the satellite field of view as well as a detailed description of the algorithm as it is applied over both ocean and land surfaces. The residual error between observed and calculated brightness temperatures is found to be an important quantity in assessing the uniqueness of the solution. It is further found that the residual error is a meaningful quantity that can be used to derive expected accuracies from this retrieval technique. Examples comparing the retrieved results as well as the detailed analysis of the algorithm performance under various circumstances are the subject of a companion paper.

  6. Role of vertical structure of cloud microphysical properties on cloud radiative forcing over the Asian monsoon region

    NASA Astrophysics Data System (ADS)

    Ravi Kiran, V.; Rajeevan, M.; Gadhavi, H.; Rao, S. Vijaya Bhaskara; Jayaraman, A.

    2015-12-01

    Five years (2006-2010) of clouds and earth's radiant energy system (CERES) and CloudSat data have been analyzed to examine the role of vertical structure of cloud microphysical properties on cloud radiative forcing (CRF) parameters at the top-of-the atmosphere over the Asian monsoon region during the summer monsoon season (June-September) and the Pacific warm pool region during April. Vertical profile of cloud properties (optical depth, cloud liquid water content and cloud ice water content) derived from CloudSat data has been used for the present analysis. Shortwave, longwave and net CRF derived from the CERES data have been used. The results suggest an imbalance between shortwave cloud radiative forcing and longwave cloud radiative forcing over the Asian monsoon region consistent with the results reported earlier. The present analysis suggests that over the Bay-of-Bengal (BoB), vertical profile of cloud microphysical properties determine more than 50 % of variance in CRF. However, over the Pacific warm pool region, cloud microphysical property profiles does not contribute significantly to variance in net CRF (<10 %). Over the BoB, large asymmetry between shortwave and longwave CRF is caused by large amounts of cloud liquid water content in the layer between the surface and 9 km. The present study highlights the importance of accurate representation of cloud microphysical properties in determining the influence of clouds on the radiative balance over the top-of-the atmosphere.

  7. KIVA-3V: A block-structured KIVA program for engines with vertical or canted valves

    SciTech Connect

    Amsden, A.A.

    1997-07-01

    This report describes an extended version of KIVA-3, known as KIVA-3V, that can model any number of vertical or canted valves in the cylinder head of an internal combustion (IC) engine. The valves are treated as solid objects that move through the mesh using the familiar snapper technique used for piston motion in KIVA-3. Because the valve motion is modeled exactly, and the valve shapes are as exact as the grid resolution will allow, the accuracy of the valve model is commensurate with that of the rest of the program. Other new features in KIVA-3V include a particle-based liquid wall film model, a new sorting subroutine that is linear in the number of nodes and preserves the original storage sequence, a mixing-controlled turbulent combustion model, and an optional RNG {kappa}-{epsilon} turbulence model. All features and capabilities of the original KIVA-3 have been retained. The grid generator, K3PREP, has been expanded to support the generation of grids with valves, along with the shaping of valve ports and runners. Graphics output options have also been expanded. The report discusses the new features, and includes four examples of grids with vertical and canted valves that are representative of IC engines in use today.

  8. Temporal variability in the vertical structure of bioluminescence in the North Atlantic Oceanic

    NASA Astrophysics Data System (ADS)

    Neilson, Douglas J.; Latz, Michael I.; Case, James F.

    1995-04-01

    The temporal and depth variability of stimulated bioluminescence at 59°N, 21°W in the North Atlantic during 1991 was measured by two bathyphotometers (BP's). A moored BP (MOORDEX) obtained a 106-day time series of bioluminescence at 50 m between May 1 and August 15. A profiling BP (high-intake, defined excitation, HIDEX) measured bioluminescence in the upper water column during cruises in May and August. MOORDEX-measured bioluminescence intensity cycled with an approximate 20-day periodicity. In May, bioluminescence was correlated with chlorophyll fluorescence with similar vertical distributions in the water column. From May to August, the mean intensity and duration of individual flash events increased, and integrated water column bioluminescence increased by a factor of 4, to 1.2×1015 quanta m-2. In August, chlorophyll fluorescence distributions and mixed layer depths were shallower than in May. Despite this, the vertical distribution of bioluminescence remained unchanged from May. The following results, potentially caused by typical seasonal changes superimposed upon short-term high variability during each cruise, suggest a change in organism assemblage between May and August: (1) increase in the intensity of flash events, (2) shift to a broader distribution of flash kinetics, and (3) loss of correlation between fluorescence and bioluminescence.

  9. Self-assembly of gold nanorods into vertically aligned, rectangular microplates with a supercrystalline structure.

    PubMed

    Xiao, Junyan; Li, Zhe; Ye, Xiaozhou; Ma, Yurong; Qi, Limin

    2014-01-21

    Vertically aligned, supercrystalline microplates with a well-defined rectangular shape were fabricated in a large area through self-assembly of gold nanorods by a novel bulk solution evaporation method. This evaporative self-assembly strategy involving continuous movement of the contact line can prevent the coffee-ring effect, thus allowing uniform deposition of discrete GNR superstructures over a large area and favoring the formation of GNR supercrystals with geometrically symmetric shapes. A mechanism based on the continuing nucleation and growth of smectic GNR superstructures accompanying the movement of the contact line was put forward for the formation of the unique GNR supercrystal arrays. Based on this mechanism, a micropatterned substrate was designed to control the nucleation location and growth direction, leading to the spontaneous self-assembly of nearly parallel arrays of vertically aligned, supercrystalline microplates of GNRs. The obtained rectangular-plate-shaped GNR supercrystals exhibited interesting anisotropic optical reflection properties, which were revealed by polarized light microscopy. PMID:24292548

  10. Polarity correspondence in metaphor congruency effects: structural overlap predicts categorization times for bipolar concepts presented in vertical space.

    PubMed

    Lakens, Daniël

    2012-05-01

    Previous research has shown that words presented on metaphor congruent locations (e.g., positive words UP on the screen and negative words DOWN on the screen) are categorized faster than words presented on metaphor incongruent locations (e.g., positive words DOWN and negative words UP). These findings have been explained in terms of an interference effect: The meaning associated with UP and DOWN vertical space can automatically interfere with the categorization of words with a metaphorically incongruent meaning. The current studies test an alternative explanation for the interaction between the vertical position of abstract concepts and the speed with which these stimuli are categorized. Research on polarity differences (basic asymmetries in the way dimensions are processed) predicts that +polar endpoints of dimensions (e.g., positive, moral, UP) are categorized faster than -polar endpoints of dimensions (e.g., negative, immoral, DOWN). Furthermore, the polarity correspondence principle predicts that stimuli where polarities correspond (e.g., positive words presented UP) provide an additional processing benefit compared to stimuli where polarities do not correspond (e.g., negative words presented UP). A meta-analysis (Study 1) shows that a polarity account provides a better explanation of reaction time patterns in previous studies than an interference explanation. An experiment (Study 2) reveals that controlling for the polarity benefit of +polar words compared to -polar words did not only remove the main effect of word polarity but also the interaction between word meaning and vertical position due to polarity correspondence. These results reveal that metaphor congruency effects should not be interpreted as automatic associations between vertical locations and word meaning but instead are more parsimoniously explained by their structural overlap in polarities.

  11. Comparing the cloud vertical structure derived from several methods based on radiosonde profiles and ground-based remote sensing measurements

    NASA Astrophysics Data System (ADS)

    Costa-Surós, M.; Calbó, J.; González, J. A.; Long, C. N.

    2014-08-01

    The cloud vertical distribution and especially the cloud base height, which is linked to cloud type, are important characteristics in order to describe the impact of clouds on climate. In this work, several methods for estimating the cloud vertical structure (CVS) based on atmospheric sounding profiles are compared, considering the number and position of cloud layers, with a ground-based system that is taken as a reference: the Active Remote Sensing of Clouds (ARSCL). All methods establish some conditions on the relative humidity, and differ in the use of other variables, the thresholds applied, or the vertical resolution of the profile. In this study, these methods are applied to 193 radiosonde profiles acquired at the Atmospheric Radiation Measurement (ARM) Southern Great Plains site during all seasons of the year 2009 and endorsed by Geostationary Operational Environmental Satellite (GOES) images, to confirm that the cloudiness conditions are homogeneous enough across their trajectory. The perfect agreement (i.e., when the whole CVS is estimated correctly) for the methods ranges between 26 and 64%; the methods show additional approximate agreement (i.e., when at least one cloud layer is assessed correctly) from 15 to 41%. Further tests and improvements are applied to one of these methods. In addition, we attempt to make this method suitable for low-resolution vertical profiles, like those from the outputs of reanalysis methods or from the World Meteorological Organization's (WMO) Global Telecommunication System. The perfect agreement, even when using low-resolution profiles, can be improved by up to 67% (plus 25% of the approximate agreement) if the thresholds for a moist layer to become a cloud layer are modified to minimize false negatives with the current data set, thus improving overall agreement.

  12. Vertical Structure Variability In The Tropical Atlantic From A High-resolution Ogcm Experiment In 1980-2000

    NASA Astrophysics Data System (ADS)

    Illig, S.; Dewitte, B.; Ayoub, N.; de Mey, P.; Du Penhoat, Y.

    We investigate the vertical structure variability in the Tropical Atlantic based on the CLIPPER project high-resolution Ocean General Circulation Model (OGCM) simula- tion for the 1980-2000 period. Near the equator the linear vertical modes are estimated at each grid point of the OGCM simulation. The contribution of baroclinic modes to surface zonal current and sea level anomalies is analyzed for interannual frequen- cies. The second baroclinic mode is the most energetic mode. The first and the third modes contribute with comparable amplitude but with different spatial distribution in the equatorial wave guide. The first mode exhibits a variability peak in the western part of the basin, where the maximum in zonal wind stress variability is observed, whereas the energy of the third baroclinic mode is confined in the east, where the largest zonal gradients in the density field and in the vertical mode characteristics are found. The summed-up contribution of the high-order baroclinic modes variability (4 to 10) is as energetic as the gravest modes and is the largest in the east. Kelvin and meridional Rossby components are derived for each of the gravest baroclinic mode contributions by projecting onto the associated meridional structures. The effects of boundaries close to the equator is taken into consideration, and shown to modify wave coefficients near the meridional boundaries as compared to the classical calculation assuming infinite meridional extension structures. We have found evidence of equato- rial Kelvin and Rossby wave propagation with phase speed values close to theoretical ones. The results are compared to equivalent ones of a multi-mode linear simulation using the projection coefficients and phase speed values derived from the OGCM sim- ulation. This, in particular, allows for separating locally wind-forced waves from free waves and deriving the boundary reflection efficiency. The analysis also reveals verti- cal propagation of the energy in the sub

  13. Ageing of aerosol and their radiative properties in the Mediterranean Basin

    NASA Astrophysics Data System (ADS)

    Roberts, Greg; Léon, Jean-François; Pont, Véronique; Mallet, Marc; Augustin, Patrick; Dulac, François; Junkermann, Wolfgang

    2014-05-01

    The VESSAER campaign (VErtical Structure and Sources of AERosols in the Mediterranean Region) identified different sources of aerosol in the Mediterranean Basin and assessed the regional impact of aerosol on cloud microphysical and radiative properties. The airborne aspect of VESSAER was conducted on an ultra-light aircraft in summer 2012. Ground-based activities included observations in the central and northern regions of Corsica, as well as aerosol LIDAR and sun photometer measurements on the eastern coast. The main scientific goals were to investigate local versus long-range sources of aerosol and cloud condensation nuclei (CCN) and their vertical structure in the lower troposphere, study evolution and ageing related to atmospheric processes, and determine aerosol direct radiative impacts over a larger spatial scale in the Mediterranean Basin. Even though Corsica is separated by from the European continent by ca. 100 km with no immediate sources of urban aerosol, the background concentrations in Corsica were similar to those in the continental European boundary layer. The background total aerosol concentrations within the boundary layer in Corsica are nearly 2000 cm-3. Nearly all of the particles in the boundary layer (> 90%) are CCN-active at 0.37% supersaturation as they had become hygroscopic during their transport. Ageing (with respect to CCN-activity) of European emissions occurred exclusively in the boundary layer and not in aerosol layers aloft. In contrast, aerosol hygroscopicity did not change as a function of transport time in elevated aerosol layers, suggesting that photochemical ageing of less hygroscopic material is relatively slow compared to ageing processes in the boundary layer. The vertical profiles clearly show the long-range transport of dust from the Saharan Desert and pollution from the European continent -- which were the two major sources of aerosol during the campaign. Two of the research flights coincided with CALIPSO overpasses, when

  14. Determination of the fine structure constant based on BLOCH oscillations of ultracold atoms in a vertical optical lattice.

    PubMed

    Cladé, Pierre; de Mirandes, Estefania; Cadoret, Malo; Guellati-Khélifa, Saïda; Schwob, Catherine; Nez, François; Julien, Lucile; Biraben, François

    2006-01-27

    We report an accurate measurement of the recoil velocity of 87Rb atoms based on Bloch oscillations in a vertical accelerated optical lattice. We transfer about 900 recoil momenta with an efficiency of 99.97% per recoil. A set of 72 measurements of the recoil velocity, each one with a relative uncertainty of about 33 ppb in 20 min integration time, leads to a determination of the fine structure constant with a statistical relative uncertainty of 4.4 ppb. The detailed analysis of the different systematic errors yields to a relative uncertainty of 6.7 ppb. The deduced value of alpha-1 is 137.035 998 78(91).

  15. Hyperfine-induced hysteretic funnel structure in spin blockaded tunneling current of coupled vertical quantum dots at low magnetic field

    SciTech Connect

    Leary, A.; Wicha, A.; Harack, B.; Coish, W. A.; Hilke, M.; Yu, G.; Gupta, J. A.; Payette, C.; Austing, D. G.

    2013-12-04

    We outline the properties of the hyperfine-induced funnel structure observed in the two-electron spin blockade region of a weakly coupled vertical double quantum dot device. Hysteretic steps in the leakage current occur due to dynamic nuclear polarization when either the bias voltage or the magnetic field is swept up and down. When the bias voltage is swept, an intriguing ∼3 mT wide cusp near 0 T appears in the down-sweep position, and when the magnetic field is swept, the current at 0 T can be switched from 'low' to 'high' as the bias is increased.

  16. Optical AND/OR gates based on monolithically integrated vertical cavity laser with depleted optical thyristor structure.

    PubMed

    Choi, Woon-Kyung; Kim, Doo-Gun; Kim, Do-Gyun; Choi, Young-Wan; Choquette, Kent D; Lee, Seok; Woo, Deok-Ha

    2006-11-27

    Latching optical switches and optical logic gates with AND and OR functionality are demonstrated for the first time by the monolithic integration of a vertical cavity lasers with depleted optical thyristor structure. The thyristors have a low threshold current of 0.65 mA and a high on/off contrast ratio of more than 50 dB. By simply changing a reference switching voltage, this single device operates as two logic functions, optical logic AND and OR. The thyristor laser fabricated by using the oxidation process and has achieved high optical output power efficiency and a high sensitivity to the optical input light.

  17. Structure of Air-Water Bubbly Flow in a Vertical Annulus

    SciTech Connect

    Rong Situ; Takashi Hibiki; Ye Mi; Mamoru Ishii; Michitsugu Mori

    2002-07-01

    Local measurements of flow parameters were performed for vertical upward bubbly flows in an annulus. The annulus channel consisted of an inner rod with a diameter of 19.1 mm and an outer round tube with an inner diameter of 38.1 mm, and the hydraulic equivalent diameter was 19.1 mm. Double-sensor conductivity probe was used for measuring void fraction, interfacial area concentration, and interfacial velocity, and Laser Doppler anemometer was utilized for measuring liquid velocity and turbulence intensity. The mechanisms to form the radial profiles of local flow parameters were discussed in detail. The constitutive equations for distribution parameter and drift velocity in the drift-flux model, and the semi-theoretical correlation for Sauter mean diameter namely interfacial area concentration, which were proposed previously, were validated by local flow parameters obtained in the experiment using the annulus. (authors)

  18. High power 808 nm vertical cavity surface emitting laser with multi-ring-shaped-aperture structure

    NASA Astrophysics Data System (ADS)

    Hao, Y. Q.; Shang, C. Y.; Feng, Y.; Yan, C. L.; Zhao, Y. J.; Wang, Y. X.; Wang, X. H.; Liu, G. J.

    2011-02-01

    The carrier conglomeration effect has been one of the main problems in developing electrically pumped high power vertical cavity surface emitting laser (VCSEL) with large aperture. We demonstrate a high power 808 nm VCSEL with multi-ring-shaped-aperture (MRSA) to weaken the carrier conglomeration effect. Compared with typical VCSEL with single large aperture (SLA), the 300-μm-diameter VCSEL with MRSA has more uniform near field and far field patterns. Moreover, MRSA laser exhibits maximal CW light output power 0.3 W which is about 3 times that of SLA laser. And the maximal wall-plug efficiency of 17.4% is achieved, higher than that of SLA laser by 10%.

  19. Field Emission Characteristics of the Structure of Vertically Aligned Carbon Nanotube Bundles.

    PubMed

    Lin, Pao-Hung; Sie, Cong-Lin; Chen, Ching-An; Chang, Hsuan-Chen; Shih, Yi-Ting; Chang, Hsin-Yueh; Su, Wei-Jhih; Lee, Kuei-Yi

    2015-12-01

    In this study, we performed thermal chemical vapor deposition for growing vertically aligned carbon nanotube (VACNT) bundles for a field emitter and applied photolithography for defining the arrangement pattern to simultaneously compare square and hexagonal arrangements by using two ratios of the interbundle distance to the bundle height (R) of field emitters. The hexagon arrangement with R = 2 had the lowest turn-on electric field (E to) and highest enhancement factor, whereas the square arrangement with R = 3 had the most stable field emission (FE) characteristic. The number density can reveal the correlation to the lowest E to and highest enhancement factor more effectively than can the R or L. The fluorescent images of the synthesized VACNT bundles manifested the uniformity of FE currents. The results of our study indicate the feasibility of applying the VACNT field emitter arrangement to achieve optimal FE performance. PMID:26183388

  20. Anisotropic photoluminescence behaviour of vertical AlGaAs structures grown on gratings

    NASA Astrophysics Data System (ADS)

    Vermeire, G.; Yu, Z. Q.; Vermaerke, F.; Buydens, L.; Van Daele, P.; Demeester, P.

    1992-11-01

    The formation of vertical AlGaAs quantum wells during MOVPE growth of AlGaAs layers on submicron gratings has been investigated. The influence of the growth temperature, growth velocity, V/III ratio and the overall Al content has been examined and explained using surface diffusion effects of the group III atoms (or reactant species). 77 K PL measurements show a polarization anisotropy and indicate lateral quantum confinement. Also the growth of QWWs on submicron gratings is reported, showing very large PL intensities and polarization anisotropy. Finally the realization of QWWs has been proposed by growing Al xGa 1- xAs/Al yGa 1- yAs QWs on gratings and based on the different surface mobilities of Ga and Al.

  1. Sampling the Vertical Moisture Structure of an Atmospheric River Event Using Airborne GPS Radio Occultation Profiling

    NASA Astrophysics Data System (ADS)

    Haase, J. S.; Malloy, K.; Murphy, B.; Sussman, J.; Zhang, W.

    2015-12-01

    Atmospheric rivers (ARs) are of high concern in California, bringing significant rain to the region over extended time periods of up to 5 days, potentially causing floods, and more importantly, contributing to the Sierra snowpack that provides much of the regional water resources. The CalWater project focuses on predicting the variability of the West Coast water supply, including improving AR forecasting. Unfortunately, data collection over the ocean remains a challenge and impacts forecasting accuracy. One novel technique to address this issue includes airborne GPS radio occultation (ARO), using broadcast GPS signals from space to measure the signal ray path bending angle and refractivity to retrieve vertical water vapor profiles. The Global Navigation Satellite System Instrument System for Multistatic and Occultation Sensing (GISMOS) system was developed for this purpose for recording and processing high-sample rate (10MHz) signals in the lower troposphere. Previous studies (Murphy et al, 2014) have shown promising results in acquiring airborne GPS RO data, comparing it to dropsondes and numerical weather models. CalWater launched a field campaign in the beginning of 2015 which included testing GISMOS ARO on the NOAA GIV aircraft for AR data acquisition, flying into the February 6th AR event that brought up to 35 cm of rain to central California. This case study will compare airborne GPS RO refractivity profiles to the NCEP-NCAR final reanalysis model and dropsonde profiles. We will show the data distribution and explain the sampling characteristics, providing high resolution vertical information to the sides of the aircraft in a manner complementary to dropsondes beneath the flight track. We will show how this method can provide additional reliable data during the development of AR storms.

  2. KINEMATICAL AND CHEMICAL VERTICAL STRUCTURE OF THE GALACTIC THICK DISK. I. THICK DISK KINEMATICS ,

    SciTech Connect

    Moni Bidin, C.; Carraro, G.; Mendez, R. A.

    2012-03-10

    The variation of the kinematical properties of the Galactic thick disk with Galactic height Z is studied by means of 412 red giants observed in the direction of the south Galactic pole up to 4.5 kpc from the plane. We confirm the non-null mean radial motion toward the Galactic anticenter found by other authors, but we find that it changes sign at |Z| = 3 kpc, and the proposed inward motion of the local standard of rest alone cannot explain these observations. The rotational velocity decreases with |Z| by -30 km s{sup -1} kpc{sup -1}, but the data are better represented by a power law with index 1.25, similar to that proposed from the analysis of Sloan Digital Sky Survey data. All the velocity dispersions increase with |Z|, but the vertical gradients are small. The dispersions grow proportionally, with no significant variation of the anisotropy. The ratio {sigma}{sub U}/{sigma}{sub W} = 2 suggests that the thick disk could have formed from a low-latitude merging event. The vertex deviation increases with Galactic height, reaching {approx}20 Degree-Sign at |Z| = 3.5 kpc. The tilt angle also increases, and the orientation of the ellipsoid in the radial-vertical plane is constantly intermediate between the alignment with the cylindrical and the spherical coordinate systems. The tilt angle at |Z| = 2 kpc coincides with the expectations of MOdified Newtonian Dynamics, but an extension of the calculations to higher |Z| is required to perform a conclusive test. Finally, between 2.5 and 3.5 kpc we detect deviations from the linear trend of many kinematical quantities, suggesting that some kinematical substructure could be present.

  3. Kinematical and Chemical Vertical Structure of the Galactic Thick Disk. I. Thick Disk Kinematics

    NASA Astrophysics Data System (ADS)

    Moni Bidin, C.; Carraro, G.; Méndez, R. A.

    2012-03-01

    The variation of the kinematical properties of the Galactic thick disk with Galactic height Z is studied by means of 412 red giants observed in the direction of the south Galactic pole up to 4.5 kpc from the plane. We confirm the non-null mean radial motion toward the Galactic anticenter found by other authors, but we find that it changes sign at |Z| = 3 kpc, and the proposed inward motion of the local standard of rest alone cannot explain these observations. The rotational velocity decreases with |Z| by -30 km s-1 kpc-1, but the data are better represented by a power law with index 1.25, similar to that proposed from the analysis of Sloan Digital Sky Survey data. All the velocity dispersions increase with |Z|, but the vertical gradients are small. The dispersions grow proportionally, with no significant variation of the anisotropy. The ratio σU/σW = 2 suggests that the thick disk could have formed from a low-latitude merging event. The vertex deviation increases with Galactic height, reaching ~20° at |Z| = 3.5 kpc. The tilt angle also increases, and the orientation of the ellipsoid in the radial-vertical plane is constantly intermediate between the alignment with the cylindrical and the spherical coordinate systems. The tilt angle at |Z| = 2 kpc coincides with the expectations of MOdified Newtonian Dynamics, but an extension of the calculations to higher |Z| is required to perform a conclusive test. Finally, between 2.5 and 3.5 kpc we detect deviations from the linear trend of many kinematical quantities, suggesting that some kinematical substructure could be present. Based on observations collected at the European Organization for Astronomical Research in the Southern Hemisphere, Chile (proposal IDs 075.B-0459(A), 077.B-0348(A)). This paper includes data gathered with the 6.5 m Magellan and the duPont Telescopes, located at Las Campanas Observatory, Chile.

  4. Vertical Distribution of Aersols and Water Vapor Using CRISM Limb Observations

    NASA Technical Reports Server (NTRS)

    Smith, Michael D.; Wolff, Michael J.; Clancy, R. Todd

    2011-01-01

    Near-infrared spectra taken in a limb-viewing geometry by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on-board the Mars Reconnaissance Orbiter (MRO) provide a useful tool for probing atmospheric structure. Specifically, the observed radiance as a function of wavelength and height above the limb allows the vertical distribution of both dust and ice aerosols to be retrieved. These data serve as an important supplement to the aerosol profiling provided by the MRO/MCS instrument allowing independent validation and giving additional information on particle physical and scattering properties through multi-wavelength studies. A total of at least ten CRISM limb observations have been taken so far covering a full Martian year. Each set of limb observations nominally contains about four dozen scans across the limb giving pole-to-pole coverage for two orbits at roughly 100 and 290 W longitude over the Tharsis and Syrtis/Hellas regions, respectively. At each longitude, limb scans are spaced roughly 10 degrees apart in latitude, with a vertical spatial resolution on the limb of roughly 800 m. Radiative transfer modeling is used to model the observations. We compute synthetic CRISM limb spectra using a discrete-ordinates radiative transfer code that accounts for multiple scattering from aerosols and accounts for spherical geometry of the limb observations by integrating the source functions along curved paths in that coordinate system. Retrieved are 14-point vertical profiles for dust and water ice aerosols with resolution of 0.4 scale heights between one and six scale heights above the surface. After the aerosol retrieval is completed, the abundances of C02 (or surface pressure) and H20 gas are retrieved by matching the depth of absorption bands at 2000 nm for carbon dioxide and at 2600 run for water vapor. In addition to the column abundance of water vapor, limited information on its vertical structure can also be retrieved depending on the signal

  5. Structure, transport, and vertical coherence of the Gulf Stream from the Straits of Florida to the Southeast Newfoundland Ridge

    NASA Astrophysics Data System (ADS)

    Meinen, Christopher S.; Luther, Douglas S.

    2016-06-01

    Data from three independent and extensive field programs in the Straits of Florida, the Mid-Atlantic Bight, and near the Southeast Newfoundland Ridge are reanalyzed and compared with results from other historical studies to highlight the downstream evolution of several characteristics of the Gulf Stream's mean flow and variability. The three locations represent distinct dynamical regimes: a tightly confined jet in a channel; a freely meandering jet; and a topographically controlled jet on a boundary. Despite these differing dynamical regimes, the Gulf Stream in these areas exhibits many similarities. There are also anticipated and important differences, such as the loss of the warm core of the current by 42°N and the decrease in the cross-frontal gradient of potential vorticity as the current flows northward. As the Gulf Stream evolves it undergoes major changes in transport, both in magnitude and structure. The rate of inflow up to 60°W and outflow thereafter are generally uniform, but do exhibit some remarkable short-scale variations. As the Gulf Stream flows northward the vertical coherence of the flow changes, with the Florida Current and North Atlantic Current segments of the Gulf Stream exhibiting distinct upper and deep flows that are incoherent, while in the Mid-Atlantic Bight the Gulf Stream exhibits flows in three layers each of which tends to be incoherent with the other layers at most periods. These coherence characteristics are exhibited in both Eulerian and stream coordinates. The observed lack of vertical coherence indicates that great caution must be exercised in interpreting proxies for Gulf Stream structure and flow from vertically-limited or remote observations.

  6. Structure, transport, and vertical coherence of the Gulf Stream from the Straits of Florida to the Southeast Newfoundland Ridge

    NASA Astrophysics Data System (ADS)

    Meinen, Christopher S.; Luther, Douglas S.

    2016-05-01

    Data from three independent and extensive field programs in the Straits of Florida, the Mid-Atlantic Bight, and near the Southeast Newfoundland Ridge are reanalyzed and compared with results from other historical studies to highlight the downstream evolution of several characteristics of the Gulf Stream's mean flow and variability. The three locations represent distinct dynamical regimes: a tightly confined jet in a channel; a freely meandering jet; and a topographically controlled jet on a boundary. Despite these differing dynamical regimes, the Gulf Stream in these areas exhibits many similarities. There are also anticipated and important differences, such as the loss of the warm core of the current by 42°N and the decrease in the cross-frontal gradient of potential vorticity as the current flows northward. As the Gulf Stream evolves it undergoes major changes in transport, both in magnitude and structure. The rate of inflow up to 60°W and outflow thereafter are generally uniform, but do exhibit some remarkable short-scale variations. As the Gulf Stream flows northward the vertical coherence of the flow changes, with the Florida Current and North Atlantic Current segments of the Gulf Stream exhibiting distinct upper and deep flows that are incoherent, while in the Mid-Atlantic Bight the Gulf Stream exhibits flows in three layers each of which tends to be incoherent with the other layers at most periods. These coherence characteristics are exhibited in both Eulerian and stream coordinates. The observed lack of vertical coherence indicates that great caution must be exercised in interpreting proxies for Gulf Stream structure and flow from vertically-limited or remote observations.

  7. Epitaxial MoS2/GaN structures to enable vertical 2D/3D semiconductor heterostructure devices

    NASA Astrophysics Data System (ADS)

    Ruzmetov, D.; Zhang, K.; Stan, G.; Kalanyan, B.; Eichfeld, S.; Burke, R.; Shah, P.; O'Regan, T.; Crowne, F.; Birdwell, A. G.; Robinson, J.; Davydov, A.; Ivanov, T.

    MoS2/GaN structures are investigated as a building block for vertical 2D/3D semiconductor heterostructure devices that utilize a 3D substrate (GaN) as an active component of the semiconductor device without the need of mechanical transfer of the 2D layer. Our CVD-grown monolayer MoS2 has been shown to be epitaxially aligned to the GaN lattice which is a pre-requisite for high quality 2D/3D interfaces desired for efficient vertical transport and large area growth. The MoS2 coverage is nearly 50 % including isolated triangles and monolayer islands. The GaN template is a double-layer grown by MOCVD on sapphire and allows for measurement of transport perpendicular to the 2D layer. Photoluminescence, Raman, XPS, Kelvin force probe microscopy, and SEM analysis identified high quality monolayer MoS2. The MoS2/GaN structures electrically conduct in the out-of-plane direction and across the van der Waals gap, as measured with conducting AFM (CAFM). The CAFM current maps and I-V characteristics are analyzed to estimate the MoS2/GaN contact resistivity to be less than 4 Ω-cm2 and current spreading in the MoS2 monolayer to be approx. 1 μm in diameter. Epitaxial MoS2/GaN heterostructures present a promising platform for the design of energy-efficient, high-speed vertical devices incorporating 2D layered materials with 3D semiconductors.

  8. The Importance of Vertical and Horizontal Dimensions of the Sediment Matrix in Structuring Nematodes Across Spatial Scales

    PubMed Central

    Vieira, Danilo Cândido; Fonseca, Gustavo

    2013-01-01

    Intensive surveys have been conducted to unravel spatial patterns of benthic infauna communities. Although it has been recognized that benthic organisms are spatially structured along the horizontal and vertical dimensions of the sediment, little is known on how these two dimensions interact with each other. In this study we investigated the interdependence between the vertical and horizontal dimensions in structuring marine nematodes assemblages. We tested whether the similarity in nematode species composition along the horizontal dimension was dependent on the vertical layer of the sediment. To test this hypothesis, three-cm interval sediment samples (15 cm depth) were taken independently from two bedforms in three estuaries. Results indicated that assemblages living in the top layers are more abundant, species rich and less variable, in terms of species presence/absence and relative abundances, than assemblages living in the deeper layers. Results showed that redox potential explained the greatest amount (12%) of variability in species composition, more than depth or particle size. The fauna inhabiting the more oxygenated layers were more homogeneous across the horizontal scales than those from the reduced layers. In contrast to previous studies, which suggested that reduced layers are characterized by a specific set of tolerant species, the present study showed that species assemblages in the deeper layers are more causal (characterized mainly by vagrant species). The proposed mechanism is that at the superficial oxygenated layers, species have higher chances of being resuspended and displaced over longer distances by passive transport, while at the deeper anoxic layers they are restricted to active dispersal from the above and nearby sediments. Such restriction in the dispersal potential together with the unfavorable environmental conditions leads to randomness in the presence of species resulting in the high variability between assemblages along the

  9. Depth-profiling of vertical sidewall nanolayers on structured wafers by grazing incidence X-ray flourescence

    NASA Astrophysics Data System (ADS)

    Hönicke, P.; Beckhoff, B.; Kolbe, M.; List, S.; Conard, T.; Struyff, H.

    2008-12-01

    The Physikalisch-Technische Bundesanstalt (PTB), Germany's national metrology institute, developed an alignment strategy to specify elemental depth profiling in vertical sidewall layers on structured wafers. For this purpose, PTB's irradiation chamber for 200 mm and 300 mm silicon wafers was used to combine total-reflection X-ray fluorescence (TXRF) and grazing incidence XRF (GIXRF) techniques by employing monochromatized undulator radiation of the BESSY II electron storage ring. 3-D test structures were fabricated to develop an optimal alignment strategy allowing for depth profiling in such nanolayers. The test structures consisted of silicon bars with widths/spacings either in the μm or in the nm range. In order to be able to differentiate the sidewalls more easily from the remainder of the structures, they were provided with an additional silicon nitride layer. Four structure types of different bar width and density parameters on two 200 mm silicon wafers were investigated. The alignment procedure developed in the present work consists of three main steps and allows for distinct excitation of multiple sidewalls of one kind. Information about depth-dependent sidewall contamination, layer thickness and composition can be obtained by this approach. First results obtained on these test structures demonstrate the application potential of this new technique. In principle, depth-dependent chemical speciation should also be possible using GIXRF in combination with near edge absorption X-ray fine structure (NEXAFS).

  10. The vertical structure of Jupiter and Saturn zonal winds from nonlinear simulations of major vortices and planetary-scale disturbances

    NASA Astrophysics Data System (ADS)

    Garcia-Melendo, E.; Legarreta, J.; Sanchez-Lavega, A.

    2012-12-01

    Direct measurements of the structure of the zonal winds of Jupiter and Saturn below the upper cloud layer are very difficult to retrieve. Except from the vertical profile at a Jupiter hot spot obtained from the Galileo probe in 1995 and measurements from cloud tracking by Cassini instruments just below the upper cloud, no other data are available. We present here our inferences of the vertical structure of Jupiter and Saturn zonal wind across the upper troposphere (deep down to about 10 bar level) obtained from nonlinear simulations using the EPIC code of the stability and interactions of large-scale vortices and planetary-scale disturbances in both planets. Acknowledgements: This work has been funded by Spanish MICIIN AYA2009-10701 with FEDER support, Grupos Gobierno Vasco IT-464-07 and UPV/EHU UFI11/55. [1] García-Melendo E., Sánchez-Lavega A., Dowling T.., Icarus, 176, 272-282 (2005). [2] García-Melendo E., Sánchez-Lavega A., Hueso R., Icarus, 191, 665-677 (2007). [3] Sánchez-Lavega A., et al., Nature, 451, 437- 440 (2008). [4] Sánchez-Lavega A., et al., Nature, 475, 71-74 (2011).

  11. Backscattering measurements of atmospheric aerosols at CO2 laser wavelengths: implications of aerosol spectral structure on differential-absorption lidar retrievals of molecular species.

    PubMed

    Ben-David, A

    1999-04-20

    The volume backscattering coefficients of atmospheric aerosol were measured with a tunable CO2 lidar system at various wavelengths in Utah (a desert environment) along a horizontal path a few meters above the ground. In deducing the aerosol backscattering, a deconvolution (to remove the smearing effect of the long CO2 lidar pulse and the lidar limited bandwidth) and a constrained-slope method were employed. The spectral shape beta(lambda) was similar for all the 13 measurements during a 3-day period. A mean aerosol backscattering-wavelength dependence beta(lambda) was computed from the measurements and used to estimate the error Delta(CL) (concentration-path-length product) in differential-absorption lidar measurements for various gases caused by the systematic aerosol differential backscattering and the error that is due to fluctuations in the aerosol backscattering. The water-vapor concentration-path-length product CL and the average concentration C = /L for a path length L computed from the range-resolved lidar measurements is consistently in good agreement with the water-vapor concentration measured by a meteorological station. However, I was unable to deduce, reliably, the range-resolved water-vapor concentration C(r), which is the derivative of the range-dependent product CL, because of the effect of residual noise caused mainly by errors in the deconvolved lidar measurements.

  12. Nabro aerosol evolution observed jointly by lidars at a mid-latitude site and CALIPSO

    NASA Astrophysics Data System (ADS)

    Zhuang, J.; Yi, F.

    2016-09-01

    Evolution of the Nabro volcanic aerosols from initially-localized plumes to a decaying hemispherically-covered layer was jointly observed by ground-based lidars at Wuhan (30.5°N, 114.4°E), China and CALIPSO. During the aerosol plume formation period, from the Nabro eruption to early July 2011, the lidar backscatter ratio related to the Nabro aerosols above Wuhan varied strongly both in vertical structure and intensity, suggesting that the Nabro aerosol distribution was horizontally inhomogeneous. The stratospheric aerosol optical depth (AOD) from CALIPSO shows that the Nabro plume first circled around the Asian monsoon anticyclone and then gradually fulfilled the whole anticyclone area with a net aerosol enhancement, which may reflect a gas-particle conversion (from sulfur dioxide gas) and/or particle injection from the upper troposphere. During the horizontal dispersion period, from early July to mid-August 2011, the stratospheric AOD over Wuhan declined rapidly since the Nabro particles were transported throughout the northern hemisphere. A nearly horizontally-uniform volcanic aerosol layer was formed. During the local cleansing period, from mid-August to the end of 2011, the Nabro aerosol layer over Wuhan had a single-peak structure and decayed uniformly. The corresponding e-folding decay time for the layer AOD is ∼130 days. The lidar measurements at Wuhan gave a small depolarization ratio and large backscatter-related Ångström exponent for the Nabro aerosols on 8 July, suggesting that the majority of these aerosols were spherical and small. The effective radius and total mass for the Nabro aerosol particles were estimated to be ∼0.26 μm and ∼0.32 Tg respectively.

  13. Assessment the Synoptic Variability of Vertical Thermal Structure in Baltic Sea Waters on the Base of in-situ Measurements

    NASA Astrophysics Data System (ADS)

    Koch, A.; Klevantsov, J.; Rozhkov, V.

    2004-12-01

    The thermal regime of sea's active layer is determined by its interaction with atmosphere, thermal balance, wind and convective water mixing. The question about assessment of synoptic variability of thermal stratification in Baltic Sea waters has not yet solved. The purpose of the present work was to determine the bounds of synoptic variability of vertical temperature profiles T(z) at the all seasons on the example of Bornholm Basin in the Baltic Sea. On the base of the large array of episodic measurements at the international stations BY, situated in key regions of the Baltic Sea, the principles of annual rhythmic of vertical distribution of water temperature are given in the paper [1]. However, this data does not allow separate the synoptic variability from seasonal and inter-annual diapasons, since measurements at fixed horizon belong to different synoptic events at different years. During 1978-1988 the State Oceanographic Institute (Leningrad/Saint-Petersburg Branch) on the base of Russian RV "Rudolf Samoylovich" was carrying out observations of hydrological and hydro-chemical elements of Baltic Sea waters at the stations BY [2]. The originality of carried out work is that for the first time continuous series of measurements for elements of vertical thermo-haline structure with duration from day to several months and discreteness of 3 hour were executed. These observations got name "Multi-daily Stations". This data alongside with the data of episodic observations allows separate synoptic variability of water temperature profile and assess its degree. Vertical thermal structure of sea waters has been typified based on the parameters of profile geometry. The degree of synoptic variability in each element of profile T(z) for all the seasons has determined. It has been showed, that the enthalpy is the optimal thermal regime parameter for separating the synoptic diapason from others. It has also been showed, that synoptic variability of water temperature in deep

  14. Aerosol-cloud-precipitation interactions in the trade wind boundary layer

    NASA Astrophysics Data System (ADS)

    Jung, Eunsil

    This dissertation includes an overview of aerosol, cloud, and precipitation properties associated with shallow marine cumulus clouds observed during the Barbados Aerosol Cloud Experiment (BACEX, March-April 2010) and a discussion of their interactions. The principal observing platform for the experiment was the Cooperative Institute for Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter (TO) research aircraft that was equipped with aerosol, cloud, and precipitation probes, standard meteorological instruments, and a up-looking cloud radar. The temporal variations and vertical distributions of aerosols observed on the 15 flights show a wide range of aerosol conditions that include the most intense African dust event observed at the Barbados surface site during all of 2010. An average CCN varied from 50 cm-3 to 800 cm -3 at super-saturation of 0.6 %, for example. The 10-day backward trajectories show that three distinctive air masses (originality of air mass as well as the vertical structure) dominate over the Eastern Caribbean (e.g., typical maritime air mass, Saharan Air Layer (SAL), Middle latitude dry air) with characteristic aerosol vertical structures. Many clouds in various phases of growth during BACEX are sampled. The maximum cloud depth observed is about less than 3 km and in most of the clouds is less than 1 km. Two types of precipitation features were observed for the shallow marine cumulus clouds with different impacts on boundary layer. In one, precipitation shafts are observed to emanate from the cloud base with evaporation in the sub-cloud layer (stabilize the sub-cloud layer). In the other, precipitation shafts emanate mainly near the cloud top on the downshear side of the cloud and evaporate in the cloud layer, leading to destabilizing the cloud layer and providing moisture to the layer. Only 42-44 % of clouds sampled were purely non-precipitating throughout the clouds; the remainder of the clouds showed precipitation somewhere in the cloud

  15. Introducing Algebraic Structures through Solving Equations: Vertical Content Knowledge for K-12 Mathematics Teachers

    ERIC Educational Resources Information Center

    Wasserman, Nicholas H.

    2014-01-01

    Algebraic structures are a necessary aspect of algebraic thinking for K-12 students and teachers. An approach for introducing the algebraic structure of groups and fields through the arithmetic properties required for solving simple equations is summarized; the collective (not individual) importance of these axioms as a foundation for algebraic…

  16. Modifying surface structure to tune surface properties of vertically aligned carbon nanotube films.

    PubMed

    Ci, Lijie; Ajayan, P M

    2010-06-01

    We report a simple etching process to modify surface of vertically aligned carbon nanotube (VACNT) arrays for their applications in superhydrophobic surface, field emission display, and sun energy conversion, etc. At a high temperature (700-800 degrees C), very low concentration water vapor in presence with Ar and hydrogen flow can be a weak oxidant, and mildly etch nanotube tips without damaging their walls. This process can be performed right after the CNT growth process. Surface of nanotube arrays becomes multi-tiered nanotube patterns with open-ended nanotubes standing straightly. Surface morphology of nanotube arrays can be tuned by changing the etching time. Water droplets on a modified nanotube surface show a large contact angle and sliding angle, which make the etched nanotube film suitable for application such as small amount liquid transport. Light absorption measurement indicated that surface roughness has no effect to improve the light absorption, indicating a different mechanism from other black material. The surface modified nanotube arrays have much increased field enhancement factor in our field emission test, showing the better field emission ability of the nanotube arrays with open tips. PMID:20355379

  17. Microwave radiometer observations of interannual water vapor variability and vertical structure over a tropical station

    NASA Astrophysics Data System (ADS)

    Renju, R.; Suresh Raju, C.; Mathew, Nizy; Antony, Tinu; Krishna Moorthy, K.

    2015-05-01

    The intraseasonal and interannual characteristics and the vertical distribution of atmospheric water vapor from the tropical coastal station Thiruvananthapuram (TVM) located in the southwestern region of the Indian Peninsula are examined from continuous multiyear, multifrequency microwave radiometer profiler (MRP) measurements. The accuracy of MRP for precipitable water vapor (PWV) estimation, particularly during a prolonged monsoon period, has been demonstrated by comparing with the PWV derived from collocated GPS measurements based on regression model between PWV and GPS wet delay component which has been developed for TVM station. Large diurnal and intraseasonal variations of PWV are observed during winter and premonsoon seasons. There is large interannual PWV variability during premonsoon, owing to frequent local convection and summer thunderstorms. During monsoon period, low interannual PWV variability is attributed to the persistent wind from the ocean which brings moisture to this coastal station. However, significant interannual humidity variability is seen at 2 to 6 km altitude, which is linked to the monsoon strength over the station. Prior to monsoon onset over the station, the specific humidity increases up to 5-10 g/kg in the altitude region above 5 km and remains consistently so throughout the active spells.

  18. The horizontal planar structure of kinetic energy in a model vertical-axis wind turbine array

    NASA Astrophysics Data System (ADS)

    Craig, Anna; Zeller, Robert; Zarama, Francisco; Weitzman, Joel; Dabiri, John; Koseff, Jeffrey

    2013-11-01

    Recent studies have indicated that arrays of vertical axis wind turbines (VAWTs) could potentially harvest significantly more power per unit land area than arrays composed of conventional horizontal axis wind turbines. However, to design VAWT arrays for optimal power conversion, a more comprehensive understanding of inter-turbine energy transfer is needed. In the presented study, a geometrically scaled array of rotating circular cylinders is used to model a VAWT array. The horizontal inter-cylinder mean fluid velocities and Reynolds stresses are measured on several cross-sections using 2D particle image velocimetry in a flume. Two orientations of the array relative to the incoming flow are tested. The results indicate that cylinder rotation drives asymmetric mean flow patterns within and above the array, resulting in non-uniform distributions of turbulent kinetic energy. The variability is observed to be directly related to the ratio of the cylinder rotation speed to the streamwise water velocity. Emphasis is placed on the implications of the asymmetries for power production. Work supported by a Stanford Graduate Fellowship to A.E.C, by funding to J.O.D. from ONR N000141211047 and the Gordon and Betty Moore Foundation through Grant GBMF2645, and by funding from the Environmental Fluid Mechanics Laboratory, Stanford University.

  19. Vertical structure of mean cross-shore currents across a barred surf zone

    USGS Publications Warehouse

    Haines, John W.; Sallenger, Asbury H.

    1994-01-01

    Mean cross-shore currents observed across a barred surf zone are compared to model predictions. The model is based on a simplified momentum balance with a turbulent boundary layer at the bed. Turbulent exchange is parameterized by an eddy viscosity formulation, with the eddy viscosity Aυ independent of time and the vertical coordinate. Mean currents result from gradients due to wave breaking and shoaling, and the presence of a mean setup of the free surface. Descriptions of the wave field are provided by the wave transformation model of Thornton and Guza [1983]. The wave transformation model adequately reproduces the observed wave heights across the surf zone. The mean current model successfully reproduces the observed cross-shore flows. Both observations and predictions show predominantly offshore flow with onshore flow restricted to a relatively thin surface layer. Successful application of the mean flow model requires an eddy viscosity which varies horizontally across the surf zone. Attempts are made to parameterize this variation with some success. The data does not discriminate between alternative parameterizations proposed. The overall variability in eddy viscosity suggested by the model fitting should be resolvable by field measurements of the turbulent stresses. Consistent shortcomings of the parameterizations, and the overall modeling effort, suggest avenues for further development and data collection.

  20. Structural Dynamic/CFD Interaction for Computation of Vertical Tail Buffet

    NASA Technical Reports Server (NTRS)

    Kandil, Osama A.; Massey, Steven J.; Sheta, Essam F.

    1996-01-01

    The multi-disciplinary problem of tail buffeting is solved using three sets of equations. The first set is the unsteady, compressible, full Navier Stokes equations which are used for obtaining the flow-field vector and the aerodynamic loads. The second set is the coupled aeroelastic equations which are used for obtaining the bending and torsional deflections of the tail. The third set is the grid-displacement equations which are used for updating the grid coordinates due to the tail deflections. For the computational applications a sharp-edged delta wing of aspect ratio one and a rectangular vertical tail of aspect ratio one placed in the plane of geometric symmetry behind the wing are considered. The configuration is pitched at a critical angle of attack (alpha = 38 deg.) which produces asymmetric, vortex-breakdown flow of the delta wing primary vortices. The results show the effects of coupled and uncoupled bending-torsional responses and the effects of the Reynolds number.

  1. Polymer stabilized vertical alignment liquid crystal display: effect of monomer structures and their stabilizing characteristics

    NASA Astrophysics Data System (ADS)

    Kwon, You Ri; Choi, Young Eun; Wen, Pushen; Lee, Byeong Hoon; Kim, Jong Chan; Lee, Myong-Hoon; Jeong, Kwang-Un; Lee, Seung Hee

    2016-04-01

    A polymer-stabilized vertical alignment (PS-VA) mode using a new type of photoreactive monomer for polymer stabilization of the liquid crystal (LC) director was developed. Conventional reactive mesogens having a higher molecular weight than those of the host LC tend to aggregate and form large-sized polymer grains when exposed to ultraviolet (UV) light, subsequently deteriorating the quality of the dark state. To address these problems, bis(4-hydroxyphenyl) diacrylates were synthesized with four different linking groups as stabilizing monomers (SMs) which have molecular weights similar to that of the host LC. Their stabilizing characteristics with respect to the molecular size and polarity of SMs were evaluated by examining the electro-optic characteristics of LC cells after UV irradiation. The results showed that the SM containing a small linking group in size between biphenyls with high polarity was favored to achieve excellent polymer stabilization. The SM containing an ether linkage showed excellent electro-optic characteristics with no large-sized polymer grains even in the absence of a photo-initiator. Consequently, we anticipate that SMs, polar and smaller in size, can improve the electro-optic characteristics in PS-VA mode.

  2. Diurnal Variation and Spatial Distribution Effects on Sulfur Speciation in Aerosol Samples as Assessed by X-Ray Absorption Near-Edge Structure (XANES)

    PubMed Central

    Pongpiachan, Siwatt; Thumanu, Kanjana; Na Pattalung, Warangkana; Hirunyatrakul, Phoosak; Kittikoon, Itthipon; Ho, Kin Fai; Cao, Junji

    2012-01-01

    This paper focuses on providing new results relating to the impacts of Diurnal variation, Vertical distribution, and Emission source on sulfur K-edge XANES spectrum of aerosol samples. All aerosol samples used in the diurnal variation experiment were preserved using anoxic preservation stainless cylinders (APSCs) and pressure-controlled glove boxes (PCGBs), which were specially designed to prevent oxidation of the sulfur states in PM10. Further investigation of sulfur K-edge XANES spectra revealed that PM10 samples were dominated by S(VI), even when preserved in anoxic conditions. The “Emission source effect” on the sulfur oxidation state of PM10 was examined by comparing sulfur K-edge XANES spectra collected from various emission sources in southern Thailand, while “Vertical distribution effects” on the sulfur oxidation state of PM10 were made with samples collected from three different altitudes from rooftops of the highest buildings in three major cities in Thailand. The analytical results have demonstrated that neither “Emission source” nor “Vertical distribution” appreciably contribute to the characteristic fingerprint of sulfur K-edge XANES spectrum in PM10. PMID:22988545

  3. Vertical distribution of non-volatile species of upper tropospheric and lower stratospheric aerosol observed by balloon-borne optical particle counter above Ny-Aalesund, Norway in the winter of 2015

    NASA Astrophysics Data System (ADS)

    Shiraishi, K.; Hayashi, M.; Shibata, T.; Neuber, R.; Ruhe, W.

    2015-12-01

    The polar lower stratosphere is the sink area of stratospheric global circulation. The composition, concentration and size distribution of aerosol in the polar stratosphere are considered to be strongly influenced by the transportations from mid-latitude to polar region and exchange of stratosphere to troposphere. In order to study the aerosol composition and size distribution in the Arctic stratosphere and the relationship between their aerosol microphysical properties and transport process, we carried out balloon-borne measurement of aerosol volatility above Ny-Aalesund, Norway in the winter of 2015. In our observation, two optical particle counters and a thermo denuder were suspended by one rubber balloon. A particle counter measured the heated aerosol size distribution (after heating at the temperature of 300 degree by the thermo denuder) and the other measured the ambient aerosol size distribution during the observation. The observation was carried out on 15 January, 2015. Balloon arrived at the height of 30km and detailed information of aerosol size distributions in upper troposphere and lower stratosphere for both heated aerosol and ambient aerosol were obtained. As a Result, the number ratio of non-volatile particles to ambient aerosol particles in lower stratosphere (11-15km) showed different feature in particle size range of fine mode (0.3aerosol particles were 1-3% in fine mode range and 7-20% in coarse mode range. They suggested that fine particles are composed dominantly of volatile species (probably sulfuric acid), and coarse particles are composed of non-volatile species such as minerals, sea-salts. In our presentation, we show the obtained aerosol size distribution and discuss the aerosol compositions and their transport process.

  4. Synthesis of Vertically-Aligned Single-Walled Carbon Nanotubes in Micro Structure of Atmospheric Pressure Non-Equilibrium Plasma

    NASA Astrophysics Data System (ADS)

    Ohnishi, Kuma; Nozaki, Tomohiro; Okazaki, Ken; Heberlein, Joachim; Kortshagen, Uwe

    Plasma enhanced chemical vapor deposition (PECVD) is recognized as one of the viable fabrication techniques of carbon nanotubes. The outstanding advantage of PECVD is that free-standing, vertically-aligned carbon nanotubes (VA-CNTs) are synthesized due to the electric field normal to the substrate. This feature draws intense attention for the fabrication of nanoelectronic devices such as high-resolution scanning nanoprobes, interconnects, and field emission devices. However, carbon nanotubes synthesized in PECVD are overwhelmingly carbon nanofibers (CNFs) or multi-walled carbon nanotubes (MWNTs) with measurable structural defects. Tremendous interest in the preparation and characterization of vertically-aligned single-walled carbon nanotubes (VA-SWNTs) and related applications had not been realized in the scope of PECVD until recently. Here we present a fabrication technique of high-purity vertically-aligned single-walled carbon nanotubes using atmospheric pressure plasma enhanced chemical vapor deposition. By now, we have developed the atmospheric pressure radio-frequency discharge (APRFD) for this purpose. Although densely mono-dispersed Fe-Co catalysts of a few nanometers is primarily responsible for VA-SWNT growth, carbon precipitation was virtually absent in the thermal CVD regime at 700°C. On the other hand, high-yield VA-SWNTs were grown at 4 μm min-1 by applying the atmospheric pressure radio-frequency discharge. The results proved that cathodic ion sheath adjacent to the substrates, where a large potential drop exists, also plays an essential role for the controlled growth of SWNTs, while ion damage to the VA-SWNTs is inherently avoided due to high collision frequency among molecules in atmospheric pressure. In this paper, operation regime of APRFD and tentative reaction mechanisms for VA-SWNT growth are discussed along with optical imaging of near substrate region of APRFD.

  5. Seasonal changes in the vertical distribution and community structure of Antarctic macrozooplankton and micronekton

    NASA Astrophysics Data System (ADS)

    Flores, Hauke; Hunt, Brian P. V.; Kruse, Svenja; Pakhomov, Evgeny A.; Siegel, Volker; van Franeker, Jan A.; Strass, Volker; Van de Putte, Anton P.; Meesters, Erik H. W. G.; Bathmann, Ulrich

    2014-02-01

    The macrozooplankton and micronekton community of the Lazarev Sea (Southern Ocean) was investigated at 3 depth layers during austral summer, autumn and winter: (1) the surface layer (0-2 m); (2) the epipelagic layer (0-200 m); and (3) the deep layer (0-3000 m). Altogether, 132 species were identified. Species composition changed with depth from a euphausiid-dominated community in the surface layer, via a siphonophore-dominated community in the epipelagic layer, to a chaetognath-dominated community in the deep layer. The surface layer community predominantly changed along gradients of surface water temperature and sea ice parameters, whereas the epipelagic community mainly changed along hydrographical gradients. Although representing only 1% of the depth range of the epipelagic layer, mean per-area macrofauna densities in the surface layer ranged at 8% of corresponding epipelagic densities in summer, 6% in autumn, and 24% in winter. Seasonal shifts of these proportional densities in abundant species indicated different strategies in the use of the surface layer, including both hibernal downward and hibernal upward shift in the vertical distribution, as well as year-round surface layer use by Antarctic krill. These findings imply that the surface layer, especially when it is ice-covered, is an important functional node of the pelagic ecosystem that has been underestimated by conventional depth-integrated sampling in the past. The exposure of this key habitat to climate-driven forces most likely adds to the known susceptibility of Antarctic pelagic ecosystems to temperature rise and changing sea ice conditions.

  6. VERTICAL STRUCTURE OF STATIONARY ACCRETION DISKS WITH A LARGE-SCALE MAGNETIC FIELD

    SciTech Connect

    Bisnovatyi-Kogan, G. S.; Lovelace, R. V. E. E-mail: RVL1@cornell.edu

    2012-05-10

    In earlier works we pointed out that the disk's surface layers are non-turbulent and thus highly conducting (or non-diffusive) because the hydrodynamic and/or magnetorotational instabilities are suppressed high in the disk where the magnetic and radiation pressures are larger than the plasma thermal pressure. Here, we calculate the vertical profiles of the stationary accretion flows (with radial and azimuthal components), and the profiles of the large-scale, magnetic field taking into account the turbulent viscosity and diffusivity and the fact that the turbulence vanishes at the surface of the disk. Also, here we require that the radial accretion speed be zero at the disk's surface and we assume that the ratio of the turbulent viscosity to the turbulent magnetic diffusivity is of order unity. Thus, at the disk's surface there are three boundary conditions. As a result, for a fixed dimensionless viscosity {alpha}-value, we find that there is a definite relation between the ratio R of the accretion power going into magnetic disk winds to the viscous power dissipation and the midplane plasma-{beta}, which is the ratio of the plasma to magnetic pressure in the disk. For a specific disk model with R of order unity we find that the critical value required for a stationary solution is {beta}{sub c} Almost-Equal-To 2.4r/({alpha}h), where h is the disk's half thickness. For weaker magnetic fields, {beta} > {beta}{sub c}, we argue that the poloidal field will advect outward while for {beta} < {beta}{sub c} it will advect inward. Alternatively, if the disk wind is negligible (R<<1), there are stationary solutions with {beta} >> {beta}{sub c}.

  7. Vertical Structure in Pluto's Atmosphere from the 2006 June 12 Stellar Occultation

    NASA Astrophysics Data System (ADS)

    Young, E. F.; French, R. G.; Young, L. A.; Ruhland, C. R.; Buie, M. W.; Olkin, C. B.; Regester, J.; Shoemaker, K.; Blow, G.; Broughton, J.; Christie, G.; Gault, D.; Lade, B.; Natusch, T.

    2008-11-01

    Pluto occultations are historically rare events, having been observed in 1988, 2002, 2006, and, as Pluto moves into the crowded Galactic plane, on several occasions in 2007. Here we present six results from our observations of the 2006 June 12 event from several sites in Australia and New Zealand. First, we show that Pluto's 2006 bulk atmospheric column abundance, as in 2002, is over twice the value measured in 1988, implying that nitrogen frost on Pluto's surface is 1.2-1.7 K warmer in 2006 than 1988 despite a 9% drop in incident solar flux. We measure a half-light shadow radius of 1216 ± 8.6 km in 2006, nominally larger than published values of 1213 ± 16 km measured in 2002. Given the current error bars, this latest half-light radius cannot discriminate between continued atmospheric growth or shrinkage, but it rules out several of the volatile transport scenarios modeled by Hansen & Paige. Second, we resolve spikes in the occultation light curve that are similar to those seen in 2002 and model the vertical temperature fluctuations that cause them. Third, we show that Pluto's upper atmosphere appears to hold a steady temperature of ~100 K, as predicted from the methane thermostat model, even at latitudes where the methane thermostat is inoperative. This implies that energy transport rates are faster than radiational cooling rates. Fourth, this occultation has provided the first significant detection of a non-isothermal temperature gradient in Pluto's upper atmosphere also reported by Elliot et al., possibly the result of CO gas in Pluto's upper atmosphere. Fifth, we show that a haze-only explanation for Pluto's light curve is extremely unlikely; a thermal inversion is necessary to explain the observed light curve. And sixth, we derive an upper limit for the haze optical depth of 0.0023 in the zenith direction at average CCD wavelengths.

  8. The Vertical Structure of Warm Ionised Gas in the Milky Way

    NASA Astrophysics Data System (ADS)

    Gaensler, B. M.; Madsen, G. J.; Chatterjee, S.; Mao, S. A.

    2008-11-01

    We present a new joint analysis of pulsar dispersion measures and diffuse Hα emission in the Milky Way, which we use to derive the density, pressure and filling factor of the thick disk component of the warm ionised medium (WIM) as a function of height above the Galactic disk. By excluding sightlines at low Galactic latitude that are contaminated by Hii regions and spiral arms, we find that the exponential scale-height of free electrons in the diffuse WIM is 1830-250+120 pc, a factor of two larger than has been derived in previous studies. The corresponding inconsistent scale heights for dispersion measure and emission measure imply that the vertical profiles of mass and pressure in the WIM are decoupled, and that the filling factor of WIM clouds is a geometric response to the competing environmental influences of thermal and non-thermal processes. Extrapolating the properties of the thick-disk WIM to mid-plane, we infer a volume-averaged electron density 0.014 +/- 0.001 cm-3, produced by clouds of typical electron density 0.34 +/- 0.06 cm-3 with a volume filling factor 0.04 +/- 0.01. As one moves off the plane, the filling factor increases to a maximum of ~30% at a height of ~1-1.5 kpc, before then declining to accommodate the increasing presence of hot, coronal gas. Since models for the WIM with a ~1 kpc scale-height have been widely used to estimate distances to radio pulsars, our revised parameters suggest that the distances to many high-latitude pulsars have been substantially underestimated.

  9. Analysis of the vertical radon structure at the Spanish "El Arenosillo" tower station.

    PubMed

    Vargas, A; Arnold, D; Adame, J A; Grossi, C; Hernández-Ceballos, M A; Bolivar, J P

    2015-01-01

    This paper presents an analysis of one year of hourly radon and meteorological measurements at 10 m and 100 m a.g.l. at El Arenosillo tall-tower station, in the south-west of the Iberian Peninsula. Whole-year and seasonal composites of the diurnal radon cycle show the expected behaviour, with larger concentrations at 10 m than at 100 m during the night, due to poor vertical mixing, and similar concentrations at both heights during the daylight hours. Wind speed and wind direction analyses by sector show the prevailing contributions for each season. Sectors with air which has spent a longer period over the ocean and high wind speeds will lead to low concentrations at both levels, whereas inland sectors show a clear increase of the concentrations with similar overall averages for the two levels. The Sierra Morena, Guadalquivir and Bethics System sectors (continental pathways) are the sectors that show higher concentrations for mild to large wind speeds. The daily evolution of radon concentration differences at both heights has been grouped into four clusters by using a K-means algorithm method. The four clusters have been selected so that they sufficiently describe different characteristics in terms of stability. The temporal evolution of the mixing height (MH) and of the bulk diffusivity parameter (Kb) during the nocturnal period has been calculated by using the temporal variation of (222)Rn concentration at 10 m and the concentration gradient with height, respectively. PMID:25464036

  10. Vertical excitation profile in diffusion injected multi-quantum well light emitting diode structure

    NASA Astrophysics Data System (ADS)

    Riuttanen, L.; Kivisaari, P.; Svensk, O.; Vasara, T.; Myllys, P.; Oksanen, J.; Suihkonen, S.

    2015-03-01

    Due to their potential to improve the performance of light-emitting diodes (LEDs), novel device structures based on nanowires, surface plasmons, and large-area high-power devices have received increasing amount of interest. These structures are almost exclusively based on the double hetero junction (DHJ) structure, that has remained essentially unchanged for decades. In this work we study a III-nitride diffusion injected light-emitting diode (DILED), in which the active region is located outside the pn-junction and the excitation of the active region is based on bipolar diffusion of charge carriers. This unorthodox approach removes the need of placing the active region in the conventional current path and thus enabling carrier injection in device structures, which would be challenging to realize with the conventional DHJ design. The structure studied in this work is has 3 indium gallium nitride / gallium nitride (InGaN/GaN) quantum wells (QWs) under a GaN pn-junction. The QWs are grown at diferent growth temperatures for obtaining distinctive luminescence peaks. This allows to obtain knowledge on the carrier diffusion in the structure. When the device is biased, all QWs emit light indicating a significant diffusion current into the QW stack.

  11. Detecting forest canopy layering: applying lidar remote sensing to further understand the role of vertical structure in species habitat preference

    NASA Astrophysics Data System (ADS)

    Whitehurst, A. S.; Dubayah, R.; Swatantran, A.

    2011-12-01

    Full waveform lidar reflects off all forest canopy elements, showing not only height, but also the structure within the canopy from the top to the forest floor, making it an ideal remote sensing technology for research in forest ecosystem dynamics. Vertical stratification or canopy layering has long been noted as an essential element in the forest ecosystem and of importance for species habitat. This project explores the utility of lidar for characterizing forest canopy layering and applying canopy layering information to better understand species habitat preference. Canopy layering will be mapped across the landscape using full-waveform lidar remote sensing data from the NASA Goddard Space Flight Center Laser Vegetation Imaging Sensor (LVIS). Two methods for quantifying layering have been developed from LVIS data collected during the summer of 2009 for Hubbard Brook Experimental Forest, New Hampshire. The two layering datasets (one categorical, one continuous) describe how vertical stratification varies across the forest with canopy height and elevation. The relationships between of canopy layering and avian species habitat preference will also be assessed for bird species within Hubbard Brook Experimental forest. These results will provide ecologically meaningful information and a relevant method for quantifying canopy layering at the landscape scale, which will aid in a better understanding of forest ecosystem dynamics for forest management and species habitat research.

  12. Autonomous Ozone and Aerosol LIDAR Profiling of the Troposphere: A Synergistic Approach

    NASA Astrophysics Data System (ADS)

    Strawbridge, K. B.

    2015-12-01

    LIDAR technology is an excellent tool to probe the complex vertical structure of the atmosphere at high spatial and temporal resolution. This provides the critical vertical context for the interpretation of ground-based chemistry measurements, airborne measurements and model/satellite verification and validation. In recent years, Environment Canada has designed several autonomous aerosol LIDAR systems for deployment across several regions of Canada. The current system builds on the successes of these autonomous LIDARS but using a synergistic approach by combining tropospheric ozone DIAL (Differential Absorption LIDAR) technology with simultaneous 3+2+1 aerosol LIDAR measurements. It operates 24 hours a day, seven days a week except during precipitation events. The system is operated remotely and the data are updated every hour to a website to allow near real-time capability. A few case studies are shown emphasizing the synergistic approach of coupling ozone and aerosol profiles to better understand air quality impacts on local and regional scales.

  13. [Vertical structure of bacterial communities in peats of the Yakhroma River floodplain].

    PubMed

    Dobrovol'skaia, T G; Golovchenko, A V; Pozdniakov, A I

    2007-01-01

    The abundance and taxonomic structure of soil bacterial communities have been studied in different geomorphological parts of the Yakhroma floodplain. It has been found that the numbers of bacteria reach a peak in calcareous peat soil under forest near the floodplain terrace, decreasing to a minimum in soddy alluvial soil near the riverbed. All soils are characterized by the presence of different ecological-trophic bacterial groups capable of peat destruction. Seasonal dynamics of the structure of bacterial communities and, in some soil types, its spatial dynamics accounted for by changes in the botanical structure of peat across its profile have been revealed. All peat soils in the floodplain have high contents of organic matter and neutral pH and, therefore, are favorable biotopes for the development of saprotrophic bacteria. This, in turn, largely accounts for high productivity and stability of this agroecosystem as a whole.

  14. [Vertical structure of bacterial communities in peats of the Yakhroma River floodplain].

    PubMed

    Dobrovol'skaia, T G; Golovchenko, A V; Pozdniakov, A I

    2007-01-01

    The abundance and taxonomic structure of soil bacterial communities have been studied in different geomorphological parts of the Yakhroma floodplain. It has been found that the numbers of bacteria reach a peak in calcareous peat soil under forest near the floodplain terrace, decreasing to a minimum in soddy alluvial soil near the riverbed. All soils are characterized by the presence of different ecological-trophic bacterial groups capable of peat destruction. Seasonal dynamics of the structure of bacterial communities and, in some soil types, its spatial dynamics accounted for by changes in the botanical structure of peat across its profile have been revealed. All peat soils in the floodplain have high contents of organic matter and neutral pH and, therefore, are favorable biotopes for the development of saprotrophic bacteria. This, in turn, largely accounts for high productivity and stability of this agroecosystem as a whole. PMID:18038631

  15. Organic aerosols

    SciTech Connect

    Penner, J.E.

    1994-01-01

    Organic aerosols scatter solar radiation. They may also either enhance or decrease concentrations of cloud condensation nuclei. This paper summarizes observed concentrations of aerosols in remote continental and marine locations and provides estimates for the sources of organic aerosol matter. The anthropogenic sources of organic aerosols may be as large as the anthropogenic sources of sulfate aerosols, implying a similar magnitude of direct forcing of climate. The source estimates are highly uncertain and subject to revision in the future. A slow secondary source of organic aerosols of unknown origin may contribute to the observed oceanic concentrations. The role of organic aerosols acting as cloud condensation nuclei (CCN) is described and it is concluded that they may either enhance or decrease the ability of anthropogenic sulfate aerosols to act as CCN.

  16. Vertical structure of atmosphere in pre-monsoon season over Bangalore

    NASA Astrophysics Data System (ADS)

    Agnihotri, Geeta; Dimri, A. P.

    2015-10-01

    This paper discusses the variation of dry bulb and dew point temperature (T and T d) on the days with and without thunderstorm (TSD and NTSD) over Bangalore during pre-monsoon season. The thermodynamic parameters like convective available potential energy (CAPE), convective inhibition energy (CIN), precipitable water content (PWC) and dynamical parameter vertical wind shear difference (VWS) are studied. The mean profiles of T, T d are generated using March-May upper air data of 1730 hrs IST from 2000-2007 for Bangalore. These are also generated on the TSD and NTSD respectively. It is found that the difference between mean profile of T for TSD/NTSD and seasonal mean is negative/positive till 200 hPa. On the other hand, the difference of the seasonal mean of T d and that of T d on the TSD/NTSD is found to be positive/negative till 300 hPa. These results are found to be significant at 99% confidence. It is found that T is less than the mean at surface till 600 hPa on TSD, whereas it is 0.5 ∘C above average on the NTSD respectively. The difference between the T d on the TSD and mean T d is of the order of 3-5 ∘C till 300 hPa. On the NTSD, this difference ranges between -1 and -2∘C in the entire troposphere. The mean values of CAPE, CIN, PWC and VWS for Bangalore in pre-monsoon season are found to be 1324, 49.3 J/kg, 30 mm and -0.0007 s -1, respectively. These parameters were used as predictors for forecasting a thunderstorm. The critical success index and Heidke skill score were used for evaluating the forecast skill of the above parameters for 2 years from 2008 to 2009. CAPE and PWC are able to distinguish a TSD from that of a NTSD with 99% confidence. It is found that these scores are 0.44 and 0.35 for CAPE and 0.49 and 0.53 for precipitable water content.

  17. Effect of Vertical Wind Shear on Numerically Simulated Multicell Storm Structure.

    NASA Astrophysics Data System (ADS)

    Fovell, Robert G.; Ogura, Yoshi

    1989-10-01

    A strictly two-dimensional cloud model was used to gauge the effect of vertical wind shear on the mature phase behavior of model-simulated multicellular storms, extending the previous work of the authors. We specifically examined the propagation speed, quasi-equilibrium behavior, storm scale and updraft orientation of the model storms as a function of shear intensity. We also considered the precipitation efficiencies of our. model storms and applied density current and Rotunno-Klemp-Weisman theories to our results.Our previous work revealed that model storms could achieve a mature phase consisting of repetitive multicellular development when certain numerical obstacles were overcome. This was referred to as a `quasi-equilibrium state.' We found herein that this state was also reached by model storms even when subjected to a very wide range of low-level wind shear intensities, although the temporal behavior during this stage was clearly dependent on the shear. We also found a very systematic relationship between the storm speed and the shear strength. Therefore, small shear values produced slowly moving storms which generally exhibited simple oscillations with time, fitting the classic multicell model. Larger shears resulted in complex oscillations similar to what has been termed `weak evolution,' culminating in a nearly unicellular storm in the most extreme case.The transition between the strongly and weakly evolving modes was abrupt in the wind shear spectrum, and the temporal behavior of the precipitation production was quite different between the two regimes. Yet, we also found that the precipitation efficiencies of these model storms were roughly constant among the simulations, irrespective of the low-level shear. The larger shear storms typically produced more precipitation, because they were processing water vapor at faster rates due to their more rapid propagation speeds, but were neither identifiably more nor less efficient in doing so. The rear inflow

  18. Structure, electrical characteristics, and high-temperature stability of aerosol jet printed silver nanoparticle films

    NASA Astrophysics Data System (ADS)

    Rahman, Md Taibur; McCloy, John; Ramana, C. V.; Panat, Rahul

    2016-08-01

    Printed electronics has emerged as a versatile eco-friendly fabrication technique to create sintered nanoparticle (NP) films on arbitrary surfaces with an excellent control over the film microstructure. While applicability of such films for high-temperature applications is not explored previously, herein we report the high-temperature electrical stability of silver (Ag) metal NP films fabricated using an Aerosol Jet based printing technique and demonstrate that this behavior is dictated by changes in the film microstructure. In-situ high temperature (24-500 °C) impedance spectroscopy measurements show that the real part of the impedance increases with increasing temperature up to 150 °C, at which point a decreasing trend prevails until 300 °C, followed again by an increase in impedance. The electrical behavior is correlated with the in-situ grain growth of the Ag NP films, as observed afterwards by scanning electron microscopy and X-ray diffraction (XRD), and could be tailored by controlling the initial microstructure through sintering conditions. Using combined diffraction and spectroscopic analytical methods, it is demonstrated the Aerosol Jet printed Ag NP films exhibit enhanced thermal stability and oxidation resistance. In addition to establishing the conditions for stability of Ag NP films, the results provide a fundamental understanding of the effect of grain growth and reduction in grain boundary area on the electrical stability of sintered NP films.

  19. Aerosols-Cloud-Microphysics Interactions in Tropical Cyclone Earl

    NASA Astrophysics Data System (ADS)

    Luna-Cruz, Yaitza

    Aerosols-cloud-microphysical processes are largely unknown in their influence on tropical cyclone evolution and intensification; aerosols possess the largest uncertainty. For example: What is the link between aerosols and cloud microphysics quantities? How efficient are the aerosols (i.e. dust from the Saharan Air Layer -SAL) as cloud condensation nuclei (CCN) and ice nuclei (IN)? Does aerosols affect the vertical velocity, precipitation rates, cloud structure and lifetime? What are the dominant factors and in which sectors of the tropical cyclone? To address some of the questions in-situ microphysics measurements from the NASA DC-8 aircraft were obtained during the Genesis and Rapid Intensification Processes (GRIP) 2010 field campaign. A total of four named storms (Earl, Gaston, Karl and Mathew) were sampled. Earl presented the excellent opportunity to study aerosols-cloud-microphysics interactions because Saharan dust was present and it underwent rapid intensification. This thesis seeks to explore hurricane Earl to develop a better understanding of the relationship between the SAL aerosols and cloud microphysics evolution. To assist in the interpretation of the microphysics observations, high resolution numerical simulations of hurricane Earl were performed using the Weather Research and Forecasting (WRF-ARW) model with the new Aerosol-Aware bulk microphysics scheme. This new version of Thompson scheme includes explicit activation of cloud condensation nuclei (CCN) from a major CCN source (i.e. sulfates and sea salt) and explicit ice nucleation (IN) from mineral dust. Three simulations are performed: (1) the Control case with the old Thompson scheme and initial conditions from GFS model, (2) the Aerosol-Aware first baseline case with GOCART aerosol module as an input conditions, and (3) the Aerosol-Aware increase case in which the GOCART aerosols concentrations were increased significantly. Overall, results of model simulations along with aircraft observations

  20. Genesis of elevated aerosol loading over the Indian region

    NASA Astrophysics Data System (ADS)

    Prijith, S. S.; Rao, P. V. N.; Mohan, Mannil

    2016-05-01

    Elevated aerosols assume importance as the diabatic heating due to aerosol absorption is more intense at higher altitudes where the atmosphere becomes thinner. Indian region, especially its central and northern latitudes, experiences significant loading of elevated aerosols during pre-monsoon and summer months. Genesis of elevated aerosol loading over Indian region is investigated in the present study, using multi-year satellite observations from Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) and Moderate Resolution Imaging Spectroradiometer (MODIS) along with reanalysis winds from MERRA. Central India is observed to have prominent aerosols loading at higher altitudes during pre-monsoon season, whereas it is during summer months over north-west India. Further analysis reveals that the elevated aerosols over Indian region in pre-monsoon and summer months are significantly contributed by transported mineral dust from the arid continental regions at west. In addition to the mineral dust advection, aerosols at higher altitudes over Indian region are enriched by strong convection and associated vertical transport of surface level aerosols. Vertical transport of aerosols observed over Indian region during pre-monsoon and summer months is aided by intense convergence at the surface level and divergence at the upper level. Moreover, aerosol source/sink strength estimated using aerosol flux continuity equation show significant aerosol production over central India during pre-monsoon. Strong vertical transport prevails during pre-monsoon uplifts the locally produced aerosols, with considerable anthropogenic fraction, to higher altitudes where their impacts would be more intense.

  1. Vertical thermal structure of the Venus atmosphere from temperature and pressure measurements

    SciTech Connect

    Linkin, V.M.; Blamon, Z.; Lipatov, A.P.; Devyatkin, S.I.; Dyachkov, A.V.; Ignatova, S.I.; Kerzhanovich, V.V.; Malyk, K.; Stadny, V.I.; Sanotskiy, Y.V.

    1986-05-01

    Accurate temperature and pressure measurements were made on the Vega-2 lander during its entire descent. The temperature and pressure at the surface were 733 K and 89.3 bar, respectively. A strong temperature inversion was found in the upper troposphere. Several layers with differing static stability were visible in the atmospheric structure.

  2. Signatures of Currency Vertices

    NASA Astrophysics Data System (ADS)

    Holme, Petter

    2009-03-01

    Many real-world networks have broad degree distributions. For some systems, this means that the functional significance of the vertices is also broadly distributed, in other cases the vertices are equally significant, but in different ways. One example of the latter case is metabolic networks, where the high-degree vertices — the currency metabolites — supply the molecular groups to the low-degree metabolites, and the latter are responsible for the higher-order biological function, of vital importance to the organism. In this paper, we propose a generalization of currency metabolites to currency vertices. We investigate the network structural characteristics of such systems, both in model networks and in some empirical systems. In addition to metabolic networks, we find that a network of music collaborations and a network of e-mail exchange could be described by a division of the vertices into currency vertices and others.

  3. Mediterranean aerosol typing by integrating three-wavelength lidar and sun photometer measurements.

    PubMed

    Perrone, M R; Burlizzi, P

    2016-07-01

    Backscatter lidar measurements at 355, 532, and 1064 nm combined with aerosol optical thicknesses (AOTs) from sun photometer measurements collocated in space and time were used to retrieve the vertical profiles of intensive and extensive aerosol parameters. Then, the vertical profiles of the Ångström coefficients for different wavelength pairs (Å(λ1, λ2, z)), the color ratio (CR(z)), the fine mode fraction (η(z)) at 532 nm, and the fine modal radius (R f (z)), which represent aerosol characteristic properties independent from the aerosol load, were used for typing the aerosol over the Central Mediterranean. The ability of the Ångström coefficients to identify the main aerosol types affecting the Central Mediterranean with the support of the backward trajectory analysis was first demonstrated. Three main aerosol types, which were designed as continental-polluted (CP), marine-polluted (MP), and desert-polluted (DP), were identified. We found that both the variability range and the vertical profile structure of the tested aerosol intensive parameters varied with the aerosol type. The variability range and the altitude dependence of the aerosol extinction coefficients at 355, 532, and 1064 nm, respectively, also varied with the identified aerosol types even if they are extensive aerosol parameters. DP, MP, and CP aerosols were characterized by the Å(532, 1064 nm) mean values ± 1 standard deviation equal to 0.5 ± 0.2, 1.1 ± 0.2, 1.6 ± 0.2, respectively. η(%) mean values ± 1SD were equal to 50 ± 10, 73 ± 7, and 86 ± 6 for DP, MP, and CP aerosols, respectively. The R f and CR mean values ± 1SD were equal to 0.16 ± 0.05 μm and 1.3 ± 0.3, respectively, for DP aerosols; to 0.12 ± 0.03 μm and 1.8 ± 0.4, respectively, for MP aerosols; and to 0.11 ± 0.02 μm and 1.7 ± 0.4, respectively, for CP aerosols. CP and DP aerosols were on average responsible for greater AOT and LR values, but

  4. The vertical disk structure of the edge-on spiral galaxy NGC 3079

    NASA Technical Reports Server (NTRS)

    Veilleux, S.; Bland-Hawthorn, Jonathan; Cecil, G.; Tully, R. B.

    1993-01-01

    NGC 3079 is an edge-on SB(s)c galaxy at a redshift of 1225 km/s relative to the Local Group. Earlier researchers found a spectacular 'figure-eight' radio structure aligned along the minor axis of the galaxy, centered on the nucleus, and extending 3 kpc above and below the plane. The geometry of this structure and the evidence of unusually high nuclear gas velocities suggest that a wind-type outflow from the nucleus is taking place. The disk of NGC 3079 is also remarkable: it is extremely rich in H 2 regions and is the only unambiguous example of a galaxy outside M31 and our own Galaxy to exhibit 'Heiles-like' shells. Other researchers have also identified a nebulosity with a ragged X-shaped morphology formed by a system of lumpy filaments with individual lengths of 3 - 5 kpc. They suggest that this material is ambient halo gas entrained into the boundary layers of the nuclear outflow. The complex structure of the line emission in NGC 3079 makes this object an ideal target for an imaging spectroscopic study. The present paper reports the preliminary results of such a study.

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  6. Forest Vertical Structure of Sierra Nevada Observed by the First Spaceborne Tandem SAR Mission

    NASA Astrophysics Data System (ADS)

    Qi, W.; Swatantran, A.; Dubayah, R.

    2015-12-01

    DLR's TerraSAR-X (TSX, 2007 launched) /TanDEM-X (TDX, 2010 launched) (abbreviated as TDM) mission is the first and sole Spaceborne tandem SAR mission, allowing for consistent and continuous mappings of global forest structure without any temporal decorrelation. This study tested performance of three single-polarized (HH) TDM acquisitions for forest structure estimation over a coniferous forest of Sierra Nevada. Complex interferometric coherences were calculated and applied in a widely used scattering model - the Random Volume over Ground (RVoG) model to retrieve the forest structural properties. Scattering phase height (SPH) was derived from the interferometric phase for an evaluation of the average scattering height of this forest and the overall penetration capability of TDM X-band signal over this area. Since only single-polarized TDM data are available, in order to keep the RVoG inversion balanced and solvable, either one of the following two strategies can be applied: 1) simulating the ground phase using a digital terrain model (DTM) from Lidar, and 2) assuming a fixed extinction coefficient value for the entire study area when a Lidar DTM is not used. This study firstly used a 5-m Lidar DTM to estimate the SPH and RVoG forest height. All SPH of the three TDM acquisitions have demonstrated strong correlations to the Lidar RH100 (canopy top height) with r2 of 0.75~0.77, bias of -11.60~-12.58m (i.e. the mean height difference between SPH and canopy top height; this bias can be associated to the average penetration depth) and RMSE of 12.79~13.73m at 90m. An r2 of 0.79~0.81, bias of 0.37~1.97m and RMSE of 5.11~5.56m was observed between all the RVoG forest height and Lidar RH100. The study also tested the second method by fixing the extinction value, i.e. without applying a Lidar DTM for the ground phase. Despite the large variety of forest density and height over this area, the derived RVoG forest height has a surprisingly good correlation to the Lidar RH100 with

  7. Experimental and numerical investigations on the performance of particle dampers attached to a primary structure undergoing free vibration in the horizontal and vertical directions

    NASA Astrophysics Data System (ADS)

    Wang, Yanrong; Liu, Bin; Tian, Aimei; Tang, Wei

    2016-06-01

    Particle damping (PD) has been well known for its simplicity and high efficiency in attenuating structure vibration. Recent studies on PD have focused mainly on new types of dampers and applications. Meanwhile, excitation applied to the primary structure is still limited to either horizontal or vertical direction, perpendicular or parallel to gravity. In this study, the characteristics of PD under horizontal-vertical excitations (HVE) are investigated numerically and experimentally. The particle damper, which is attached to the top free end of an L-shaped cantilever beam, is simultaneously excited in the horizontal and vertical directions in the context of free decay. An equivalent model capable of motion in both the horizontal and vertical directions is generated. Given an initial displacement disturbance, this model starts vibrating freely in the vertical plane. A code based on the 3D discrete element method is programmed, and the high coincidence between the numerical and experimental results shows that this equivalent model is capable of high-fidelity simulation for PD under HVE. Parametric studies have been implemented to characterize the basic nonlinear damping capacity of particle dampers under this new operating condition. The effects of seven dimensionless independent parameters on the specific damping capacity (SDC) are investigated, including dimensionless acceleration amplitude, particle mass ratio, dimensionless horizontal and vertical impact clearances, coefficients of friction and restitution, and amplitude ratio of the horizontal excitation to the vertical excitation. The results show that the basic damping properties of PD under HVE are similar to those of PD under only vertical excitation. However, PD under HVE signifies its own characteristics because of the existence of horizontal excitation: (1) The impact clearances in both the horizontal and vertical directions have significant effects on the SDC because of the significant increase in oblique

  8. Effects of Reduced Surface Tension on Liquid Film Structure in Vertical Upward Gas-Liquid Annular Flows

    NASA Astrophysics Data System (ADS)

    Furukawa, Tohru; Matsuyama, Fuminori; Sadatomi, Michio

    The purpose of this study is to investigate experimentally the effects of reduced surface tension on the liquid film structure in vertical-upward air-liquid annular flows in a 19.2 mm i.d. and 5.4 m long circular tube. The test liquid was water and/or a dilute water solution of Polyoxyethylene-Lauryl-Ether, and the surface tension of these liquids ranged from 72 to 45 dyne/cm. The liquid film structure was observed by use of both the still photographs and the maps of time and spatial characteristics of peripheral-mean liquid film thickness detected with a series of 63 liquid holdup sensors each axially 15 mm apart in a constant current method. The parameters studied were the wave heights of the liquid film, the passing frequencies of the waves, the mean value and the standard deviation of the wave velocities, each determined from the liquid film thickness signals through a computer program of signal processing. From the observations of still photographs and the maps of time and spatial characteristics of peripheral-mean liquid film thickness, it was cleared that the liquid film structure depends strongly on the surface tension, i.e., the reduction of surface tension makes the passing of the large waves decrease remarkably, the wave height of the large waves lower like small waves, the passing of the small waves more frequent, and the small wave velocity faster.

  9. On salinity regimes and the vertical structure of residual flows in narrow tidal estuaries

    NASA Astrophysics Data System (ADS)

    Prandle, D.

    1985-05-01

    An examination is made of the circulation in narrow estuaries subject to a predominant tidal forcing. Velocity structures are derived separately for residual flow components associated with (a) river flow, (b) wind stress, (c) a well-mixed longitudinal density gradient and (d) a fully stratified saline wedge. Dimensionless parameters are introduced to indicate the magnitude of each component and these parameters are evaluated for 9 major estuaries, thereby revealing their sensitivity to each component. For a channel of constant breadth and depth, formulae are deduced for the length of saline intrusion, L. Comparisons with observed data show that such formulae may be used with confidence to predict changes in L arising from variations in river flow, tidal range or channel depths. The level of stratification is shown to be related to a product of two parameters, one associated with velocity structure and a second involving the square of the 'flow ratio' overlineu/û (i.e. residual velocity/amplitude of the tidal velocity). This relationship provides a simple classification system for estuarine stratification which can be used to indicate the sensitivity of any particular estuary to changing conditions.

  10. CMOS-compatible method for doping of buried vertical polysilicon structures by solid phase diffusion

    NASA Astrophysics Data System (ADS)

    Turkulets, Yury; Silber, Amir; Ripp, Alexander; Sokolovsky, Mark; Shalish, Ilan

    2016-03-01

    Polysilicon receives attention nowadays as a means to incorporate 3D-structured photonic devices into silicon processes. However, doping of buried layers of a typical 3D structure has been a challenge. We present a method for doping of buried polysilicon layers by solid phase diffusion. Using an underlying silicon oxide layer as a dopant source facilitates diffusion of dopants into the bottom side of the polysilicon layer. The polysilicon is grown on top of the oxide layer, after the latter has been doped by ion implantation. Post-growth heat treatment drives in the dopant from the oxide into the polysilicon. To model the process, we studied the diffusion of the two most common silicon dopants, boron (B) and phosphorus (P), using secondary ion mass spectroscopy profiles. Our results show that shallow concentration profiles can be achieved in a buried polysilicon layer using the proposed technique. We present a quantitative 3D model for the diffusion of B and P in polysilicon, which turns the proposed method into an engineerable technique.

  11. Experimental study of interfacial structure of a falling liquid film in a vertical pipe

    NASA Astrophysics Data System (ADS)

    Hasan, Abbas; Azzopardi, Barry; Hewakandamby, Buddhika

    2015-11-01

    Many studies in the literature provide time series data of the film thickness at one or two points on the pipe wall. Most of these studies focussed on either flat plates or small diameter pipes. The main aim of this paper is to study the characteristics of the interfacial wave structure of falling liquid films (liquid Reynolds numbers: 618-1670) in a large diameter pipe (127 mm) using a Multiple Pin Film Sensor (MPFS) which is capable of providing measurements of film thickness and interfacial waves with excellent resolution in time and in the circumferential and axial directions. Parameters, such as film thicknesses, wave velocities and frequencies were extracted. 3D interfacial wave structures were reconstructed from the film thickness data. Unlike the waves in smaller diameter pipes which are characterised as coherent rings, the waves seen in this study were much localized. The mean film thicknesses are generally i