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Sample records for aerosol layer products

  1. 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.

  2. 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.

  3. Composition and physical properties of the Asian Tropopause Aerosol Layer and the North American Tropospheric Aerosol Layer

    PubMed Central

    Yu, Pengfei; Toon, Owen B; Neely, Ryan R; Martinsson, Bengt G; Brenninkmeijer, Carl A M

    2015-01-01

    Recent studies revealed layers of enhanced aerosol scattering in the upper troposphere and lower stratosphere over Asia (Asian Tropopause Aerosol Layer (ATAL)) and North America (North American Tropospheric Aerosol Layer (NATAL)). We use a sectional aerosol model (Community Aerosol and Radiation Model for Atmospheres (CARMA)) coupled with the Community Earth System Model version 1 (CESM1) to explore the composition and optical properties of these aerosol layers. The observed aerosol extinction enhancement is reproduced by CESM1/CARMA. Both model and observations indicate a strong gradient of the sulfur-to-carbon ratio from Europe to the Asia on constant pressure surfaces. We found that the ATAL is mostly composed of sulfates, surface-emitted organics, and secondary organics; the NATAL is mostly composed of sulfates and secondary organics. The model also suggests that emission increases in Asia between 2000 and 2010 led to an increase of aerosol optical depth of the ATAL by 0.002 on average which is consistent with observations. Key Points The Asian Tropopause Aerosol Layer is composed of sulfate, primary organics, and secondary organics The North American Tropospheric Aerosol Layer is mostly composed of sulfate and secondary organics Aerosol Optical Depth of Asian Tropopause Aerosol Layer increases by 0.002 from 2000 to 2010 PMID:26709320

  4. Combined CALIPSO & SAGE II Observations of Asian Tropopause Aerosol Layer

    NASA Astrophysics Data System (ADS)

    Thomason, Larry; Vernier, J.-P.

    2012-07-01

    Observations by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) revealed the presence of an aerosol layer associated with the Asian monsoon anticyclone. While variable in magnitude from season to season, it is apparent in all years since the beginning of the CALIPSO mission in 2006 though partially masked in years by significant volcanic activity. The Stratospheric Aerosol and Gas Experiment (SAGE II) made observations of the upper troposphere and stratosphere from 1984 through the end of its mission in 2005. Aerosol observations by SAGE II in this region of the atmosphere are complicated by cloud presence and past studies had not revealed the presence of this feature. While a cloud detection algorithm had been developed in the past Kent et al. (1997 a, b), it was known that some very thin cloud events were misclassified as aerosol and made the interpretation of observations over southern Asia difficult to interpret. Recently, we have modified the Kent cloud/aerosol separation algorithm by incorporating elements of a technique developed by Mike Pitts et al. for CALIPSO PSC identification. The new method is more effective in the identification of very thin clouds than the Kent method (which has been used as a cloud flag within the data product). Using this method for the post-Pinatubo period (1998-2005), we observe a tropical UTLS aerosol feature that occurs in Northern Hemisphere Summer that stretches from Indonesia over southern Asia toward Africa that is very consistent with the ATAL features found in CALIPSO observations. However, it is not observed in the data set prior to 1998 including periods in the late 1980s and perhaps as early as the late 1970s (using SAGE I observations). In fact, prior to 1998, this region of the atmosphere is observed to be an area of relatively low aerosol loading. In this presentation, we will show the process of identifying the ATAL aerosol layer in the CALIPSO and SAGE data products. While we

  5. Dust layer profiling using an aerosol dropsonde

    NASA Astrophysics Data System (ADS)

    Ulanowski, Zbigniew; Kaye, Paul Henry; Hirst, Edwin; Wieser, Andreas; Stanley, Warren

    2015-04-01

    Routine meteorological data is obtained in the atmosphere using disposable radiosondes, giving temperature, pressure, humidity and wind speed. Additional measurements are obtained from dropsondes, released from research aircraft. However, a crucial property not yet measured is the size and concentration of atmospheric particulates, including dust. Instead, indirect measurements are employed, relying on remote sensing, to meet the demands from areas such as climate research, air quality monitoring, civil emergencies etc. In addition, research aircraft can be used in situ, but airborne measurements are expensive, and aircraft use is restricted to near-horizontal profiling, which can be a limitation, as phenomena such as long-range transport depend on the vertical distribution of aerosol. The Centre for Atmospheric and Instrumentation Research at University of Hertfordshire develops light-scattering instruments for the characterization of aerosols and cloud particles. Recently a range of low-cost, miniature particle counters has been created, intended for use with systems such as disposable balloon-borne radiosondes, dropsondes, or in dense ground-based sensor networks. Versions for different particle size ranges exist. They have been used for vertical profiling of aerosols such as mineral dust or volcanic ash. A disadvantage of optical particle counters that sample through a narrow inlet is that they can become blocked, which can happen in cloud, for example. Hence, a different counter version has been developed, which can have open-path geometry, as the sensing zone is defined optically rather than being delimited by the flow system. This counter has been used for ground based air-quality monitoring around Heathrow airport. The counter has also been adapted for use with radiosondes or dropsondes. The dropsonde version has been successfully tested by launching it from research aircraft together with the so-called KITsonde, developed at the Karlsruhe Institute of

  6. 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

  7. Effect of stratospheric aerosol layers on the TOMS/SBUV ozone retrieval

    NASA Technical Reports Server (NTRS)

    Torres, O.; Ahmad, Zia; Pan, L.; Herman, J. R.; Bhartia, P. K.; Mcpeters, R.

    1994-01-01

    An evaluation of the optical effects of stratospheric aerosol layers on total ozone retrieval from space by the TOMS/SBUV type instruments is presented here. Using the Dave radiative transfer model we estimate the magnitude of the errors in the retrieved ozone when polar stratospheric clouds (PSC's) or volcanic aerosol layers interfere with the measurements. The largest errors are produced by optically thick water ice PSC's. Results of simulation experiments on the effect of the Pinatubo aerosol cloud on the Nimbus-7 and Meteor-3 TOMS products are presented.

  8. The MODIS Aerosol Algorithm, Products and Validation

    NASA Technical Reports Server (NTRS)

    Remer, L. A.; Kaufman, Y. J.; Tanre, D.; Mattoo, S.; Chu, D. A.; Martins, J. V.; Li, R.-R.; Ichoku, C.; Levy, R. C.; Kleidman, R. G.

    2003-01-01

    The MODerate resolution Imaging Spectroradiometer (MODIS) aboard both NASA's Terra and Aqua satellites is making near global daily observations of the earth in a wide spectral range. These measurements are used to derive spectral aerosol optical thickness and aerosol size parameters over both land and ocean. The aerosol products available over land include aerosol optical thickness at three visible wavelengths, a measure of the fraction of aerosol optical thickness attributed to the fine mode and several derived parameters including reflected spectral solar flux at top of atmosphere. Over ocean, the aerosol optical thickness is provided in seven wavelengths from 0.47 microns to 2.13 microns. In addition, quantitative aerosol size information includes effective radius of the aerosol and quantitative fraction of optical thickness attributed to the fine mode. Spectral aerosol flux, mass concentration and number of cloud condensation nuclei round out the list of available aerosol products over the ocean. The spectral optical thickness and effective radius of the aerosol over the ocean are validated by comparison with two years of AERONET data gleaned from 133 AERONET stations. 8000 MODIS aerosol retrievals colocated with AERONET measurements confirm that one-standard deviation of MODIS optical thickness retrievals fall within the predicted uncertainty of delta tauapproximately equal to plus or minus 0.03 plus or minus 0.05 tau over ocean and delta tay equal to plus or minus 0.05 plus or minus 0.15 tau over land. 271 MODIS aerosol retrievals co-located with AERONET inversions at island and coastal sites suggest that one-standard deviation of MODIS effective radius retrievals falls within delta r_eff approximately equal to 0.11 microns. The accuracy of the MODIS retrievals suggests that the product can be used to help narrow the uncertainties associated with aerosol radiative forcing of global climate.

  9. Multi-Sensor Aerosol Products Sampling System

    NASA Technical Reports Server (NTRS)

    Petrenko, M.; Ichoku, C.; Leptoukh, G.

    2011-01-01

    Global and local properties of atmospheric aerosols have been extensively observed and measured using both spaceborne and ground-based instruments, especially during the last decade. Unique properties retrieved by the different instruments contribute to an unprecedented availability of the most complete set of complimentary aerosol measurements ever acquired. However, some of these measurements remain underutilized, largely due to the complexities involved in analyzing them synergistically. To characterize the inconsistencies and bridge the gap that exists between the sensors, we have established a Multi-sensor Aerosol Products Sampling System (MAPSS), which consistently samples and generates the spatial statistics (mean, standard deviation, direction and rate of spatial variation, and spatial correlation coefficient) of aerosol products from multiple spacebome sensors, including MODIS (on Terra and Aqua), MISR, OMI, POLDER, CALIOP, and SeaWiFS. Samples of satellite aerosol products are extracted over Aerosol Robotic Network (AERONET) locations as well as over other locations of interest such as those with available ground-based aerosol observations. In this way, MAPSS enables a direct cross-characterization and data integration between Level-2 aerosol observations from multiple sensors. In addition, the available well-characterized co-located ground-based data provides the basis for the integrated validation of these products. This paper explains the sampling methodology and concepts used in MAPSS, and demonstrates specific examples of using MAPSS for an integrated analysis of multiple aerosol products.

  10. Enhancement of atmospheric radiation by an aerosol layer

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  11. Enhancement of atmospheric radiation by an aerosol layer.

    PubMed

    Michelangeli, D V; Allen, M; Yung, Y L; Shia, R L; Crisp, D; Eluszkiewicz, J

    1992-01-20

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

  12. Variability of Biomass Burning Aerosols Layers and Near Ground

    NASA Astrophysics Data System (ADS)

    Vasilescu, Jeni; Belegante, Livio; Marmureanu, Luminita; Toanca, Flori

    2016-06-01

    The aim of this study is to characterize aerosols from both chemical and optical point of view and to explore the conditions to sense the same particles in elevated layers and at the ground. Three days of continuous measurements using a multi-wavelength depolarization lidar(RALI) and a C-ToF-AMS aerosol mass spectrometer are analyzed. The presence of smoke particles was assessed in low level layers from RALI measurements. Chemical composition of submicronic volatile/semi-volatile aerosols at ground level was monitored by the CTOF AMS Several episodes of biomass burning aerosols have been identified by both techniques due to the presence of specific markers (f60, linear particle depolarization ratio, Ängström exponent).

  13. Quasi-biennial oscillation of the tropical stratospheric aerosol layer

    NASA Astrophysics Data System (ADS)

    Hommel, R.; Timmreck, C.; Giorgetta, M. A.; Graf, H. F.

    2015-05-01

    This study describes how aerosol in an aerosol-coupled climate model of the middle atmosphere is influenced by the quasi-biennial oscillation (QBO) during times when the stratosphere is largely unperturbed by volcanic material. In accordance with satellite observations, the vertical extent of the stratospheric aerosol layer in the tropics is modulated by the QBO by up to 6 km, or ~ 35% of its mean vertical extent between 100-7 hPa (about 16-33 km). Its largest vertical extent lags behind the occurrence of strongest QBO westerlies. The largest reduction lags behind maximum QBO easterlies. Strongest QBO signals in the aerosol surface area (30 %) and number densities (up to 100% e.g. in the Aitken mode) are found in regions where aerosol evaporates, that is above the 10 hPa pressure level (~ 31 km). Positive modulations are found in the QBO easterly shear, negative modulations in the westerly shear. Below 10 hPa, in regions where the aerosol mixing ratio is largest (50-20 hPa, or ~ 20-26 km), in most of the analysed parameters only moderate statistically significant QBO signatures (< 10%) have been found. QBO signatures in the model prognostic aerosol mixing ratio are significant at the 95% confidence level throughout the tropical stratosphere where modelled mixing ratios exceed 0.1 ppbm. In some regions of the tropical lower stratosphere the QBO signatures in other analysed parameters are partly not statistically significant. Peak-to-peak amplitudes of the QBO signature in the prognostic mixing ratios are up to twice as large as seasonal variations in the region where aerosols evaporate and between 70-30 hPa. Between the tropical tropopause and 70 hPa the QBO signature is relatively weak and seasonal variations dominate the variability of the simulated Junge layer. QBO effects on the upper lid of the tropical aerosol layer turn the quasi-static balance between processes maintaining the layer's vertical extent into a cyclic balance when considering this dominant mode

  14. Secondary Aerosol Formation in the planetary boundary layer observed by aerosol mass spectrometry on a Zeppelin NT

    NASA Astrophysics Data System (ADS)

    Rubach, Florian; Trimborn, Achim; Mentel, Thomas; Wahner, Andreas; Zeppelin Pegasos-Team 2012

    2014-05-01

    The airship Zeppelin NT is an airborne platform capable of flying at low speed throughout the entire planetary boundary layer (PBL). In combination with the high scientific payload of more than 1 ton, the Zeppelin is an ideal platform to study regional processes in the lowest layers of the atmosphere with high spatial resolution. Atmospheric aerosol as a medium long lived tracer substance is of particular interest due to its influence on the global radiation budget. Due its lifetime of up to several days secondaray aerosol at a certain location can result from local production or from transport processes. For aerosol measurements on a Zeppelin, a High-Resolution Time-of-Flight Aerosol Mass spectrometer (DeCarlo et al, 2006) was adapted to the requirements posed by an airborne platform. A weight reduction of over 20 % compared to the commercial instrument was achieved, while space occupation and footprint were each reduced by over 25 %. Within the PEGASOS project, the instrument was part of 10 measurement flight days over the course of seven weeks. Three flights were starting from Rotterdam, NL, seven flights were starting from Ozzano in the Po Valley, IT. Flight patterns included vertical profiles to study the dynamics of the PBL and cross sections through regions of interest to shed light on local production and transport processes. Analysis of data from transects between the Apennin and San Pietro Capofiume in terms of "residence time of air masses in the Po valley" indicates that aerosol nitrate has only local sources while aerosol sulfate is dominated by transport. The organic aerosol component has significant contributions of both processes. The local prodcution yields are commensurable with imultaneously observed precursor concentrations and oxidant levels. The PEGASOS project is funded by the European Commission under the Framework Programme 7 (FP7-ENV-2010-265148). DeCarlo, P.F. et al (2006), Anal. Chem., 78, 8281-8289.

  15. The Two-Column Aerosol Project: Phase I—Overview and impact of elevated aerosol layers on aerosol optical depth

    NASA Astrophysics Data System (ADS)

    Berg, Larry K.; Fast, Jerome D.; Barnard, James C.; Burton, Sharon P.; Cairns, Brian; Chand, Duli; Comstock, Jennifer M.; Dunagan, Stephen; Ferrare, Richard A.; Flynn, Connor J.; Hair, Johnathan W.; Hostetler, Chris A.; Hubbe, John; Jefferson, Anne; Johnson, Roy; Kassianov, Evgueni I.; Kluzek, Celine D.; Kollias, Pavlos; Lamer, Katia; Lantz, Kathleen; Mei, Fan; Miller, Mark A.; Michalsky, Joseph; Ortega, Ivan; Pekour, Mikhail; Rogers, Ray R.; Russell, Philip B.; Redemann, Jens; Sedlacek, Arthur J.; Segal-Rosenheimer, Michal; Schmid, Beat; Shilling, John E.; Shinozuka, Yohei; Springston, Stephen R.; Tomlinson, Jason M.; Tyrrell, Megan; Wilson, Jacqueline M.; Volkamer, Rainer; Zelenyuk, Alla; Berkowitz, Carl M.

    2016-01-01

    The Two-Column Aerosol Project (TCAP), conducted from June 2012 through June 2013, was a unique study designed to provide a comprehensive data set that can be used to investigate a number of important climate science questions, including those related to aerosol mixing state and aerosol radiative forcing. The study was designed to sample the atmosphere between and within two atmospheric columns; one fixed near the coast of North America (over Cape Cod, MA) and a second moveable column over the Atlantic Ocean several hundred kilometers from the coast. The U.S. Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) was deployed at the base of the Cape Cod column, and the ARM Aerial Facility was utilized for the summer and winter intensive observation periods. One important finding from TCAP is that four of six nearly cloud-free flight days had aerosol layers aloft in both the Cape Cod and maritime columns that were detected using the nadir pointing second-generation NASA high-spectral resolution lidar (HSRL-2). These layers contributed up to 60% of the total observed aerosol optical depth (AOD). Many of these layers were also intercepted by the aircraft configured for in situ sampling, and the aerosol in the layers was found to have increased amounts of biomass burning material and nitrate compared to aerosol found near the surface. In addition, while there was a great deal of spatial and day-to-day variability in the aerosol chemical composition and optical properties, no systematic differences between the two columns were observed.

  16. Aerosols optical propertites in Titan's Detached Haze Layer

    NASA Astrophysics Data System (ADS)

    Seignovert, Benoît; Rannou, Pascal; Lavvas, Panayotis; Cours, Thibaud; West, Robert A.

    2016-06-01

    Titan's Detached Haze Layer (DHL) first observed in 1983 by Rages and Pollack during the Voyager 2 [1] is a consistent spherical haze feature surrounding Titan's upper atmosphere and detached from the main haze. Since 2005, the Imaging Science Subsystem (ISS) instrument on board the Cassini mission performs a continuous survey of the Titan's atmosphere and confirmed its persistence at 500 km up to the equinox (2009) before its drop and disappearance in 2012 [2]. Previous analyses showed, that this layer corresponds to the transition area between small spherical aerosols and large fractal aggregates and play a key role in the aerosols formation in Titan's atmosphere [3-5]. In this study we perform UV photometric analyses on ISS observations taken from 2005 to 2007 based on radiative transfer inversion to retrieve aerosols particles properties in the DHL (bulk and monomer size, fractal dimension and local density).

  17. Stratocumulus cloud thickening beneath layers of absorbing smoke aerosol

    NASA Astrophysics Data System (ADS)

    Wilcox, E. M.

    2010-08-01

    Marine stratocumulus cloud properties, and the free-tropospheric environment above them, are examined in NASA A-train satellite data for cases where smoke from seasonal burning of the West African savannah overlay the persistent southeast Atlantic stratocumulus cloud deck. CALIPSO space-borne lidar observations show that features identified as layers of aerosol occur predominantly between 2 km and 4 km altitude with double the frequency of occurrence of aerosol features in the boundary layer. Layers identified as cloud features occur predominantly below 1.5 km altitude and beneath the layer of elevated smoke aerosol. The diurnal mean shortwave heating rates attributable to the absorption of solar energy in the aerosol layer is nearly 1.5 K d-1 for an aerosol optical thickness value of 1, and increases to 1.8 K d-1 when the smoke resides above clouds owing to the additional component of upward solar radiation reflected by the cloud. As a consequence of this heating, the 700 hPa air temperature above the cloud deck is warmer by approximately 1 K on average for cases where smoke is present above the cloud compared to cases without smoke above cloud. The warmer conditions in the free-troposphere above the cloud during smoke events coincide with cloud liquid water path values that are greater by 20 g m-2 and cloud tops that are lower by approximately 50 m for overcast conditions compared to smoke-free periods. The observed thickening and subsidence of the cloud layer are consistent with published results of large-eddy simulations showing that solar absorption by smoke above stratocumulus clouds increases the buoyancy of free-tropospheric air above the temperature inversion capping the boundary layer. Increased buoyancy inhibits the entrainment of dry air through the cloud-top, thereby helping to preserve humidity and cloud cover in the boundary layer. The greater liquid water path for cases of smoke overlaying cloud implies a negative semi-direct radiative forcing of

  18. On the source of organic acid aerosol layers above clouds.

    PubMed

    Sorooshian, Armin; Lu, Miao-Ling; Brechtel, Fred J; Jonsson, Haflidi; Feingold, Graham; Flagan, Richard C; Seinfeld, John H

    2007-07-01

    During the July 2005 Marine Stratus/Stratocumulus Experiment (MASE) and the August-September 2006 Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS), the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter probed aerosols and cumulus clouds in the eastern Pacific Ocean off the coast of northern California and in southeastern Texas, respectively. An on-board particle-into-liquid sampler (PILS) quantified inorganic and organic acid species with < or = 5-min time resolution. Ubiquitous organic aerosol layers above cloud with enhanced organic acid levels were observed in both locations. The data suggest that aqueous-phase reactions to produce organic acids, mainly oxalic acid, followed by droplet evaporation is a source of elevated organic acid aerosol levels above cloud. Oxalic acid is observed to be produced more efficiently relative to sulfate as the cloud liquid water content increases, corresponding to larger and less acidic droplets. As derived from large eddy simulations of stratocumulus underthe conditions of MASE, both Lagrangian trajectory analysis and diurnal cloudtop evolution provide evidence that a significant fraction of the aerosol mass concentration above cloud can be accounted for by evaporated droplet residual particles. Methanesulfonate data suggest that entrainment of free tropospheric aerosol can also be a source of organic acids above boundary layer clouds.

  19. 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.

  20. Aerosol in the upper layer of earth's atmosphere

    NASA Astrophysics Data System (ADS)

    Morozhenko, A. V.; Vidmachenko, A. P.; Nevodovskii, P. V.

    2013-09-01

    Aerosol layers exist in the upper atmospheres of Venus, Mars, Jupiter, Saturn and the Earth. The reason for their existence may be meteorites, rings, and removal of particles of planetary origin. Observations from 1979 to 1992 showed that the optical thickness of aerosol over the Earth's polar regions changed from tau =0.0002 up to tau =.1 for lambda = 1000 nm. The greatest values of tau were in 1984 and 1992 and they were preceded by a strong volcanic activity of El Chichon (1982) and Pinatubo (1991). We show that the above-mentioned increase in the optical thickness of the stratosphere aerosol can lead to the ozone layer decrease detected in 1970. The stratospheric aerosol nature (real part of refractive index), effective particle size r and changing tau with latitude remain un solved. Among distance methods for the determination of nr and r efficient is the analysis of the phase dependence of the polarization degree. The observational values of the intensity and pol arization degree invisible light are due to optical properties of the surface and optical thickness of the atmosphere, the values of which vary with latitude, longitude and time. Therefore, it is impossible to identify accurately the stratospheric aerosol contribution. When observing in UV at lambda < 300 nm, the ozone layer cuts off the influence of the surface and the Earth's atmosphere to an altitude from 20 to 25 km. In this spectral region some negative factors can take place, namely, the emission of various gases playing depolarizing role, horizontal inhomogeneity of the effective optical thickness of ozone layer, and oriented particles (the polarization plane variation points to their presence).

  1. Lidar observations of high-altitude aerosol layers (cirrus clouds)

    NASA Astrophysics Data System (ADS)

    Deleva, Atanaska D.; Grigorov, Ivan V.

    2013-03-01

    Aerosols, clouds and aerosol-cloud interactions are recognized as the key factors influencing the climate. Clouds are the primary modulators of the Earth's radiative budget. This paper focuses on the detection of high-altitude aerosol layers in the troposphere over mid-latitude lidar station in Sofia, Bulgaria. They are situated in the height-region 6 km÷16 km, with thickness in the range 0.2 km÷5 km and have varying optical characteristics. On the basis of the general utilized classification of the Cirrus clouds, high values of the calculated atmospheric backscatter coefficient and Angströmexponent estimation results we conclude that the registered strongly scattered aerosol layers are Cirrus clouds. Lidar measurements are performed with an aerosol lidar, equipped with Nd:YAG laser at wavelengths 532 nm and 1064 nm. Mainly, lidar data are presented in terms of vertical atmospheric backscatter coefficient profiles. We also include 2Dcolormap in height-time coordinates build on the basis of so called range corrected signals. It shows in general changes of the aerosol stratification over the lidar station during the measurement period. We employed HYSPLIT backward trajectories and DREAM forecasts to analyze the lidar profile outlines and characterize the events during which Cirrus cloud samples were observed. So was remarked that most of the results were obtained during Saharan dust long-way transport over the city of Sofia. Reported experimental examples are extracted from regular lidar investigations of the atmosphere within the frame of European project EARLINET.

  2. Developments in the Aerosol Layer Height Retrieval Algorithm for the Copernicus Sentinel-4/UVN Instrument

    NASA Astrophysics Data System (ADS)

    Nanda, Swadhin; Sanders, Abram; Veefkind, Pepijn

    2016-04-01

    The Sentinel-4 mission is a part of the European Commission's Copernicus programme, the goal of which is to provide geo-information to manage environmental assets, and to observe, understand and mitigate the effects of the changing climate. The Sentinel-4/UVN instrument design is motivated by the need to monitor trace gas concentrations and aerosols in the atmosphere from a geostationary orbit. The on-board instrument is a high resolution UV-VIS-NIR (UVN) spectrometer system that provides hourly radiance measurements over Europe and northern Africa with a spatial sampling of 8 km. The main application area of Sentinel-4/UVN is air quality. One of the data products that is being developed for Sentinel-4/UVN is the Aerosol Layer Height (ALH). The goal is to determine the height of aerosol plumes with a resolution of better than 0.5 - 1 km. The ALH product thus targets aerosol layers in the free troposphere, such as desert dust, volcanic ash and biomass during plumes. KNMI is assigned with the development of the Aerosol Layer Height (ALH) algorithm. Its heritage is the ALH algorithm developed by Sanders and De Haan (ATBD, 2016) for the TROPOMI instrument on board the Sentinel-5 Precursor mission that is to be launched in June or July 2016 (tentative date). The retrieval algorithm designed so far for the aerosol height product is based on the absorption characteristics of the oxygen-A band (759-770 nm). The algorithm has heritage to the ALH algorithm developed for TROPOMI on the Sentinel 5 precursor satellite. New aspects for Sentinel-4/UVN include the higher resolution (0.116 nm compared to 0.4 for TROPOMI) and hourly observation from the geostationary orbit. The algorithm uses optimal estimation to obtain a spectral fit of the reflectance across absorption band, while assuming a single uniform layer with fixed width to represent the aerosol vertical distribution. The state vector includes amongst other elements the height of this layer and its aerosol optical

  3. Stratocumulus cloud thickening beneath layers of absorbing smoke aerosol

    NASA Astrophysics Data System (ADS)

    Wilcox, E. M.

    2010-12-01

    Marine stratocumulus cloud properties, and the free-tropospheric environment above them, are examined in NASA A-Train satellite data for cases where smoke from seasonal burning of the West African savannah overlay the persistent southeast Atlantic stratocumulus cloud deck. CALIPSO space-borne lidar observations show that features identified as layers of aerosol occur predominantly between 2 km and 4 km. Layers identified as cloud features occur predominantly below 1.5 km altitude and beneath the layer of elevated smoke aerosol. The diurnal mean shortwave heating rates attributable to the absorption of solar energy in the aerosol layer is nearly 1.5 K d-1 for an aerosol optical thickness value of 1, and increases to 1.8 K d-1 when the smoke resides above clouds owing to the additional component of upward solar radiation reflected by the cloud. As a consequence of this heating, the 700 hPa air temperature above the cloud deck is warmer by approximately 1 K on average for cases where smoke is present above the cloud compared to cases without smoke above cloud. The warmer conditions in the free-troposphere above the cloud during smoke events coincide with cloud liquid water path values that are greater by 20 g m-2 and cloud tops that are lower for overcast conditions compared to periods with low amounts of smoke. The observed thickening and subsidence of the cloud layer are consistent with published results of large-eddy simulations showing that solar absorption by smoke above stratocumulus clouds increases the buoyancy of free-tropospheric air above the temperature inversion capping the boundary layer. Increased buoyancy inhibits the entrainment of dry air through the cloud-top, thereby helping to preserve humidity and cloud cover in the boundary layer. The direct radiative effect of absorbing aerosols residing over a bright cloud deck is a positive radiative forcing (warming) at the top of the atmosphere. However, the greater liquid water path for cases of smoke

  4. Global Measurement of Junge Layer Stratospheric Aerosol with OMPS/LP. Scattering Properties and Particle Size

    NASA Astrophysics Data System (ADS)

    Rault, D. F.; Bhartia, P. K.

    2014-12-01

    The OMPS/LP was launched on board the NPP space platform in October 2011. Over the past two years, the OMPS/LP was used to retrieve the global distribution of ozone and aerosol. The paper will describe the aerosol product, which NASA is presently preparing for public release. The current OMPS/LP aerosol product consists of latitude-altitude curtains along the NPP Sun-synchronous orbit, from cloud top to about 40 km. These curtains extend from local sunrise in Southern polar region to local sunset in Northern polar region. Aerosol extinctions are produced at five distinct wavelengths, namely 513, 525, 670, 750 and 870 nm, with a sampling of 1 km in vertical direction and 1 degree latitude in the along-track direction. The OMPS/LP aerosol dataset is fairly large, with 7000 vertical profiles produced each day for each wavelength. The aerosol product will be presented in terms of extinction monthly median values and mean Angstrom coefficient (particle size). Over the past two years, the Junge layer was affected by several events such as volcanic eruptions (Nabro and Kelut) and a meteor (Chelyabinsk), the effects of which are clearly visible in the OMPS/LP dataset. The Asian Tropopause Aerosol Layer (ATAL) can also be observed in the OMPS/LP dataset. Moreover the effect of the Brewer Dobson Circulation (BDC) can be observed at high altitudes: the BDC velocity at 35 km can be estimated from the time variation of iso-density heights and was found to compare well with BDC velocities evaluated with the water vapor tape recorder technique as well as MERRA model values. Finally, aerosol filaments are clearly visible in OMPS/LP aerosol dataset as they appear as distinct "bubbles" on the OMPS/LP curtain files at periodic intervals in both the Southern and Northern hemispheres. These filaments are a main source of transport from tropical to polar region, and OMPS/LP data can therefore be instrumental in quantifying the rate of this transport. The quality of the OMPS/LP aerosol

  5. Aerosols optical properties in Titan's Detached Haze Layer

    NASA Astrophysics Data System (ADS)

    Seignovert, Benoit; Rannou, Pascal; Lavvas, Panayotis; West, Robert

    2016-10-01

    Titan's Detached Haze Layer (DHL) was first observed in 1983 by Rages and Pollack during the Voyager 2 is a consistent spherical haze feature surrounding Titan's upper atmosphere and detached from the main haze. Since 2005, the Imaging Science Subsystem (ISS) instrument on board the Cassini mission performs a continuous survey of the Titan's atmosphere and confirmed its persistence at 500 km up to the equinox (2009) before its drop and disappearance in 2012 (West et al. 2011). Previous analyses showed, that this layer corresponds to the transition area between small spherical aerosols and large fractal aggregates and play a key role in the aerosols formation in Titan's atmosphere (Rannou et al. 2000, Lavvas et al. 2009, Cours et al. 2011).In this talk we will present the UV photometric analyses based on radiative transfer inversion to retrieve aerosols particles properties in the DHL (bulk and monomer radius and local density) performed on ISS observations taken from 2005 to 2007.References:- Rages and Pollach, Icarus 55 (1983)- West, et al., Icarus 38 (2011)- Rannou, et al., Icarus 147 (2000)- Lavvas, et al., Icarus 201 (2009)- Cours, et al., ApJ Lett. 741 (2015)

  6. Silicon production in an aerosol reactor

    NASA Technical Reports Server (NTRS)

    Wu, J. J.; Flagan, R. C.

    1986-01-01

    An aerosol reactor system was developed in which large particles of silicon can be grown by silane pyrolysis. To grow particles to sizes larger than one micron, vapor deposition must be used to grow a relatively small number of seed particles. Suppression of nucleation is achieved by limiting the rate of gas phase chemical reactions such that the condensible products of the gas phase chemical reactions diffuse to the surface of the seed particles as rapidly as they are produced. This prevents high degrees of supersaturation and runaway nucleation during the growth process. Particles on the order of 10 microns were grown repeatedly with the present aersol reactor. The nucleation controlled aerosol reactor is, therefore, a suitable system for the production of powders that can readily be separated from the gas by aerodynamic means.

  7. Assessment of 10-Year Global Record of Aerosol Products from the OMI Near-UV Algorithm

    NASA Astrophysics Data System (ADS)

    Ahn, C.; Torres, O.; Jethva, H. T.

    2014-12-01

    Global observations of aerosol properties from space are critical for understanding climate change and air quality applications. The Ozone Monitoring Instrument (OMI) onboard the EOS-Aura satellite provides information on aerosol optical properties by making use of the large sensitivity to aerosol absorption and dark surface albedo in the UV spectral region. These unique features enable us to retrieve both aerosol extinction optical depth (AOD) and single scattering albedo (SSA) successfully from radiance measurements at 354 and 388 nm by the OMI near UV aerosol algorithm (OMAERUV). Recent improvements to algorithms in conjunction with the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Atmospheric Infrared Sounder (AIRS) carbon monoxide data also reduce uncertainties due to aerosol layer heights and types significantly in retrieved products. We present validation results of OMI AOD against space and time collocated Aerosol Robotic Network (AERONET) measured AOD values over multiple stations representing major aerosol episodes and regimes. We also compare the OMI SSA against the inversion made by AERONET as well as an independent network of ground-based radiometer called SKYNET in Japan, China, South-East Asia, India, and Europe. The outcome of the evaluation analysis indicates that in spite of the "row anomaly" problem, affecting the sensor since mid-2007, the long-term aerosol record shows remarkable sensor stability. The OMAERUV 10-year global aerosol record is publicly available at the NASA data service center web site (http://disc.sci.gsfc.nasa.gov/Aura/data-holdings/OMI/omaeruv_v003.shtml).

  8. 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.

  9. Impacts of elevated-aerosol-layer and aerosol type on the correlation of AOD and particulate matter with ground-based and satellite measurements in Nanjing, southeast China.

    PubMed

    Han, Yong; Wu, Yonghua; Wang, Tijian; Zhuang, Bingliang; Li, Shu; Zhao, Kun

    2015-11-01

    Assessment of the correlation between aerosol optical depth (AOD) and particulate matter (PM) is critical to satellite remote sensing of air quality, e.g. ground PM10 and ground PM2.5. This study evaluates the impacts of aloft-aerosol-plume and aerosol-type on the correlation of AOD-PM by using synergistic measurement of a polarization-sensitive Raman-Mie lidar, CIMEL sunphotometer (SP) and TEOM PM samplers, as well as the satellite MODIS and CALIPSO, during April to July 2011 in Nanjing city (32.05(○)N/118.77(○)E), southeast China. Aloft-aerosol-layer and aerosol types (e.g. dust and non-dust or urban aerosol) are identified with the range-resolved polarization lidar and SP measurements. The results indicate that the correlations for AOD-PM10 and AOD-PM2.5 can be much improved when screening out the aloft-aerosol-layer. The linear regression slopes show significant differences for the dust and non-dust dominant aerosols in the planetary boundary layer (PBL). In addition, we evaluate the recent released MODIS-AOD product (Collection 6) from the "dark-target" (DT) and "deep-blue" (DB) algorithms and their correlation with the PM in Nanjing urban area. The results verify that the MODIS-DT AODs show a good correlation (R = 0.89) with the SP-AOD but with a systematic overestimate. In contrast, the MODIS-DB AOD shows a moderate correlation (R = 0.66) with the SP-AOD but with a smaller regression intercept (0.07). Furthermore, the moderately high correlations between the MODIS-AOD and PM10 (PM2.5) are indicated, which suggests the feasibility of PM estimate using the MODIS-AOD in Nanjing city. PMID:26071961

  10. Relating Aerosol Mass and Optical Depth in the Summertime Continental Boundary Layer

    NASA Astrophysics Data System (ADS)

    Brock, C. A.; Wagner, N.; Middlebrook, A. M.; Attwood, A. R.; Washenfelder, R. A.; Brown, S. S.; McComiskey, A. C.; Gordon, T. D.; Welti, A.; Carlton, A. G.; Murphy, D. M.

    2014-12-01

    Aerosol optical depth (AOD), the column-integrated ambient aerosol light extinction, is determined from satellite and ground-based remote sensing measurements. AOD is the parameter most often used to validate earth system model simulations of aerosol mass. Relating aerosol mass to AOD, however, is problematic due to issues including aerosol water uptake as a function of relative humidity (RH) and the complicated relationship between aerosol physicochemical properties and light extinction. Measurements of aerosol microphysical, chemical, and optical properties help to constrain the relationship between aerosol mass and optical depth because aerosol extinction at ambient RH is a function of the abundance, composition and size distribution of the aerosol. We use vertical profiles of humidity and dry aerosol extinction observed in the southeastern United States (U.S.) to examine the relationship between submicron aerosol mass concentration and extinction at ambient RH. We show that the κ-Köhler parameterization directly, and without additional Mie calculations, describes the change in extinction with varying RH as a function of composition for both aged aerosols typical of the polluted summertime continental boundary layer and the biomass burning aerosols we encountered. We calculate how AOD and the direct radiative effect in the eastern U.S. have likely changed due to trends in aerosol composition in recent decades. We also examine the sensitivity of AOD to the RH profile and to aerosol composition, size distribution and abundance.

  11. Production flux of sea spray aerosol

    SciTech Connect

    de Leeuw, G.; Lewis, E.; Andreas, E. L.; Anguelova, M. D.; Fairall, C. W.; O’Dowd, C.; Schulz, M.; Schwartz, S. E.

    2011-05-07

    Knowledge of the size- and composition-dependent production flux of primary sea spray aerosol (SSA) particles and its dependence on environmental variables is required for modeling cloud microphysical properties and aerosol radiative influences, interpreting measurements of particulate matter in coastal areas and its relation to air quality, and evaluating rates of uptake and reactions of gases in sea spray drops. This review examines recent research pertinent to SSA production flux, which deals mainly with production of particles with r{sub 80} (equilibrium radius at 80% relative humidity) less than 1 {micro}m and as small as 0.01 {micro}m. Production of sea spray particles and its dependence on controlling factors has been investigated in laboratory studies that have examined the dependences on water temperature, salinity, and the presence of organics and in field measurements with micrometeorological techniques that use newly developed fast optical particle sizers. Extensive measurements show that water-insoluble organic matter contributes substantially to the composition of SSA particles with r{sub 80} < 0.25 {micro}m and, in locations with high biological activity, can be the dominant constituent. Order-of-magnitude variation remains in estimates of the size-dependent production flux per white area, the quantity central to formulations of the production flux based on the whitecap method. This variation indicates that the production flux may depend on quantities such as the volume flux of air bubbles to the surface that are not accounted for in current models. Variation in estimates of the whitecap fraction as a function of wind speed contributes additional, comparable uncertainty to production flux estimates.

  12. Coherent Evaluation of Aerosol Data Products from Multiple Satellite Sensors

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles

    2011-01-01

    Aerosol retrieval from satellite has practically become routine, especially during the last decade. However, there is often disagreement between similar aerosol parameters retrieved from different sensors, thereby leaving users confused as to which sensors to trust for answering important science questions about the distribution, properties, and impacts of aerosols. As long as there is no consensus, and the inconsistencies are not well characterized and understood, there will be no way of developing reliable model inputs and climate data records from satellite aerosol measurements. Fortunately, the Aerosol Robotic Network (AERONET) is providing well-calibrated globally representative ground-based aerosol measurements corresponding to the satellite-retrieved products. Through a recently developed web-based Multi-sensor Aerosol Products Sampling System (MAPSS), we are utilizing the advantages offered by collocated AERONET and satellite products to characterize and evaluate aerosol retrieval from multiple sensors. Indeed, MAPSS and its companion statistical tool AeroStat are facilitating detailed comparative uncertainty analysis of satellite aerosol measurements from Terra-MODIS, Aqua-MODIS, Terra-MISR, Aura-OMI, Parasol-POLDER, and Calipso-CALIOP. In this presentation, we will describe the strategy of the MAPSS system, its potential advantages for the aerosol community, and the preliminary results of an integrated comparative uncertainly analysis of aerosol products from multiple satellite sensors.

  13. Long Range Transport of Amazon Aerosol in the Free Troposphere: Influence of Amazon Combustion Aerosol on CCN in the Pacific Marine Boundary Layer

    NASA Astrophysics Data System (ADS)

    Howell, S. G.; Clarke, A. D.; Freitag, S.; Kapustin, V.; Hudson, J.; Campos, T.; Pollack, I. B.; Heizer, C. G.; Weinheimer, A. J.

    2008-12-01

    The Pacific Atmosphere Sulfur Experiment (PASE, Sept. 2007) on the NCAR C-130 aircraft was based in the Equatorial Pacific to explore the remote marine sulfur cycle. We investigated sources that control particle number and cloud condensation nuclei, CCN, in the clean marine boundary layer (MBL). Earlier studies here demonstrated particle number above the MBL was dominated by natural production of new volatile particles in cloud outflow. However, during PASE we also found coated refractory aerosol (non-volatile at 350C) aloft were linearly related to ozone concentrations and were effective CCN at 0.2% supersaturation. These aerosol had larger diameters than naturally produced volatile aerosol and trajectory analysis traced them back to deep convection in biomass burning haze over the Amazon basin over 10,000km away. These refractory soot and/or organic aerosol appear to be detrained from deep convective clouds after the near- source scavenging of larger sizes that dominate the smoke/haze aerosol mass. Following transport and once mixed into MBL they were found to account for as much as 30% of the CCN at the value of 0.2%S (a typical value for small trade-wind cumulus clouds). Hence, cloud-scavenged combustion derived aerosol, too small to be detectable optically in satellite plumes, appears to provide seed nuclei for CCN in the remote marine boundary layer. This acts over hemispheric scales for this region and presumably elsewhere. Hence; various mechanisms including convective scavenging, long range transport, particle production aloft, entrainment into the MBL, boundary layer nucleation and sea-salt production all need to be considered in modeling the MBL CCN population.

  14. Model representations of aerosol layers transported from North America over the Atlantic Ocean during the Two-Column Aerosol Project

    NASA Astrophysics Data System (ADS)

    Fast, Jerome D.; Berg, Larry K.; Zhang, Kai; Easter, Richard C.; Ferrare, Richard A.; Hair, Johnathan W.; Hostetler, Chris A.; Liu, Ying; Ortega, Ivan; Sedlacek, Arthur; Shilling, John E.; Shrivastava, Manish; Springston, Stephen R.; Tomlinson, Jason M.; Volkamer, Rainer; Wilson, Jacqueline; Zaveri, Rahul A.; Zelenyuk, Alla

    2016-08-01

    The ability of the Weather Research and Forecasting model with chemistry (WRF-Chem) version 3.7 and the Community Atmosphere Model version 5.3 (CAM5) in simulating profiles of aerosol properties is quantified using extensive in situ and remote sensing measurements from the Two-Column Aerosol Project (TCAP) conducted during July of 2012. TCAP was supported by the U.S. Department of Energy's Atmospheric Radiation Measurement program and was designed to obtain observations within two atmospheric columns; one fixed over Cape Cod, Massachusetts, and the other several hundred kilometers over the ocean. The performance is quantified using most of the available aircraft and surface measurements during July, and 2 days are examined in more detail to identify the processes responsible for the observed aerosol layers. The higher-resolution WRF-Chem model produced more aerosol mass in the free troposphere than the coarser-resolution CAM5 model so that the fraction of aerosol optical thickness above the residual layer from WRF-Chem was more consistent with lidar measurements. We found that the free troposphere layers are likely due to mean vertical motions associated with synoptic-scale convergence that lifts aerosols from the boundary layer. The vertical displacement and the time period associated with upward transport in the troposphere depend on the strength of the synoptic system and whether relatively high boundary layer aerosol concentrations are present where convergence occurs. While a parameterization of subgrid scale convective clouds applied in WRF-Chem modulated the concentrations of aerosols aloft, it did not significantly change the overall altitude and depth of the layers.

  15. Two years of free-tropospheric aerosol layers observed over Portugal by lidar

    NASA Astrophysics Data System (ADS)

    PreißLer, J.; Wagner, F.; Guerrero-Rascado, J. L.; Silva, A. M.

    2013-05-01

    Multi-wavelength Raman light detection and ranging (lidar) observations were analyzed, which were performed in Évora, Portugal, during more than 2 years on a regular basis in the framework of the European Aerosol Research Lidar Network (EARLINET). An aerosol characterization in terms of the lidar ratios at 355 and 532 nm and the extinction and backscatter related Ångström exponents is presented. Aerosol layers in the free troposphere were classified according to their origin. Clear differences in the intensive optical properties were found for layers of mineral dust from the Sahara and from Asia, of anthropogenic aerosol from Europe and from North America, as well as of biomass burning smoke from the Iberian Peninsula and from North America, respectively. In general, the mean Ångström exponents of aerosol layers of the same type, but from closer source regions, were smaller than those from aerosol layers transported over a longer distance. This hints at the deposition of large particles along the transportation path, especially for anthropogenic aerosol and mineral dust. Besides, the seasonal behavior of aerosol in the free troposphere over Évora was studied. Seventy-three percent of the detected layers were observed during spring and summer. On average, the layers were highest in summer with an overall mean layer height of (3.8 ±1.9) km above sea level (asl), and lowest in winter with (2.3 ±0.9) km asl.

  16. 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.

  17. Understanding the Processes Controlling Aerosol-Cloud Interactions in the Arctic Marine Boundary Layer

    NASA Astrophysics Data System (ADS)

    Browse, J.; Carslaw, K. S.; Pringle, K.; Mann, G.; Reddington, C.; Brooks, I. M.; Mulcahy, J.; Young, G.; Allan, J. D.; Liu, D.; Trembath, J.; Dean, A.; Yoshioka, M.

    2015-12-01

    Here we use multiple configurations of the UKCA chemistry and aerosol scheme in a global climate model, capable of simulating cloud condensation nuclei (CCN) and cloud droplet number, to understand the processes controlling aerosol-cloud interactions in the marine Arctic boundary layer. Evaluation against an unprecedented number of aerosol and cloud observations made available through the Global Aerosol Synthesis and Science Project (GASSP), International Arctic Systems for Observing the Atmosphere (IASOA) and the 2013 ACCACIA campaign, suggest that Arctic summertime CCN is well represented in the model. Sensitivity studies indicate that DMS derived nucleation events are the primary source of Arctic summertime aerosol increasing mean (median) surface CCN concentrations north of 70N from 21(14) cm-3 to 46(33) cm-3. However, evaluation against observed aerosol size distributions suggests that UKCA overestimates nucleation mode (~10nm) particle concentrations either due to overestimation of boundary layer nucleation rates or underestimation of the Arctic marine boundary layer condensation sink.

  18. 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.

  19. Uncertainty in Cloud Aerosol Transport System (CATS) Doppler Lidar Products and Measurements

    NASA Astrophysics Data System (ADS)

    Selmer, P. A.

    2010-12-01

    The Cloud Aerosol Transport System (CATS) is both a high spectral resolution lidar and Doppler lidar currently being developed at NASA Goddard Space Flight Center for use as a demonstrator instrument for NASA’s Aerosol Cloud Ecosystem (ACE) Mission. CATS is intended to fly on NASA’s high-altitude ER-2 aircraft. CATS will be capable of measuring both aerosol properties and horizontal wind velocity as a function of altitude. The accuracy of these measurements is important to the success of the instrument and the ACE mission. Uncertainty equations for both the aerosol and wind products are derived. Initially the only sources of error are assumed to be instrument error in the spectral measurements. Using simulated CATS spectral measurements from simulated atmospheric profiles (an atmosphere with only a cirrus layer, an atmosphere with only a cumulus layer, an atmosphere with only an aerosol layer, and an atmosphere with no clouds or aerosols), the uncertainty in the aerosol and wind products are calculated. These calculated uncertainties are found to be within reason. Also worthy of consideration is the effect of aircraft motion on CATS’ wind measurements and products. An equation for the the nadir angle (assumed to be about 45 degrees for CATS), as well as the uncertainty in this angle, in terms of aircraft pitch and roll is derived. The effect of uncertainty in this angle on the uncertainty in CATS aerosol and wind products is calculated using the same simulated data previously mentioned, which is found to be insignificant for normal, steady flight.

  20. “Lidar Investigations of Aerosol, Cloud, and Boundary Layer Properties Over the ARM ACRF Sites”

    SciTech Connect

    Ferrare, Richard; Turner, David

    2015-01-13

    Project goals; Characterize the aerosol and ice vertical distributions over the ARM NSA site, and in particular to discriminate between elevated aerosol layers and ice clouds in optically thin scattering layers; Characterize the water vapor and aerosol vertical distributions over the ARM Darwin site, how these distributions vary seasonally, and quantify the amount of water vapor and aerosol that is above the boundary layer; Use the high temporal resolution Raman lidar data to examine how aerosol properties vary near clouds; Use the high temporal resolution Raman lidar and Atmospheric Emitted Radiance Interferometer (AERI) data to quantify entrainment in optically thin continental cumulus clouds; and Use the high temporal Raman lidar data to continue to characterize the turbulence within the convective boundary layer and how the turbulence statistics (e.g., variance, skewness) is correlated with larger scale variables predicted by models.

  1. Measurements and determination of the marine coarse aerosol fluxes in near marine boundary layer.

    NASA Astrophysics Data System (ADS)

    Markuszewski, Piotr; Petelski, Tomasz; Zielinski, Tymon; Strzalkowska, Agata; Pakszys, Paulina; Makuch, Przemyslaw; Kowalczyk, Jakub

    2014-05-01

    Studies of production and transport of aerosol over the sea are very important for many areas of knowledge. Marine aerosols emitted from the sea surface help to clean the boundary layer from other aerosol particles. The emitted droplets do not dry out in the highly humid surface layer air and because of their sizes most of them are deposited quickly at the sea surface. Therefore, marine aerosols have many features of rain i.e. the deposition in the marine boundary layer in high wind events is controlled not only by the "dry" processes but also by the "wet" scavenging. During a number of cruises conducted on board of r/v Oceania between 2008 and 2012 we collected much data which were further used to calculate sea salt source function over the Baltic Sea. Measurements were carried out using a gradient method. For this method we used a Laser Particle Counter (PMS model CSASP-100_HV) placed on one of the masts of the boat. Measurements were performed at five different levels above the sea level: 8, 11, 14, 17 and 20 meters. The vertical aerosol concentration gradient was obtained from a minimum of 4 measurement series. Thus each result consists of a 1 hour series with the average sampling time at each elevation equaling to 8 minutes. Based on the averaged vertical concentration, and using the Monin Obukhov theory, profiles of vertical sea spray fluxes in the near water layer were calculated. Using the results from those experiments the sea spray emission fluxes have been calculated for all particles of sizes at ranges from 0.5 μm to 8 μm, as well as for particles of sizes from fifteen channels of 0.5 μm width. Using these fluxes we calculated the Sea Salt Generation Function (SSGF) over the Baltic Sea. This function provides information on the emission of particles of different sizes, depending on environmental parameters. The emission of sea spray depends on the magnitude of energy lost by the wind waves in the process of their collapse. The support for this study

  2. CALIPSO Data Products Catalog

    Atmospheric Science Data Center

    2013-11-12

    ... aerosol, and stratospheric subtypes The cloud layer fraction was added to the aerosol profile data products. The aerosol layer fraction and surface winds were added to the cloud profile data product. ...

  3. Fractionation of sulfur isotopes during heterogeneous oxidation of SO2 on sea salt aerosol: a new tool to investigate non-sea salt sulfate production in the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Harris, E.; Sinha, B.; Hoppe, P.; Foley, S.; Borrmann, S.

    2012-05-01

    The oxidation of SO2 to sulfate on sea salt aerosols in the marine environment is highly important because of its effect on the size distribution of sulfate and the potential for new particle nucleation from H2SO4 (g). However, models of the sulfur cycle are not currently able to account for the complex relationship between particle size, alkalinity, oxidation pathway and rate - which is critical as SO2 oxidation by O3 and Cl catalysis are limited by aerosol alkalinity, whereas oxidation by hypohalous acids and transition metal ions can continue at low pH once alkalinity is titrated. We have measured 34S/32S fractionation factors for SO2 oxidation in sea salt, pure water and NaOCl aerosol, as well as the pH dependency of fractionation. Oxidation of SO2 by NaOCl aerosol was extremely efficient, with a reactive uptake coefficient of ≈0.5, and produced sulfate that was enriched in 32S with αOCl = 0.9882±0.0036 at 19 °C. Oxidation on sea salt aerosol was much less efficient than on NaOCl aerosol, suggesting alkalinity was already exhausted on the short timescale of the experiments. Measurements at pH = 2.1 and 7.2 were used to calculate fractionation factors for each step from SO2(g) → multiple steps → SOOCl2-. Oxidation on sea salt aerosol resulted in a lower fractionation factor than expected for oxidation of SO32- by O3 (αseasalt = 1.0124±0.0017 at 19 °C). Comparison of the lower fractionation during oxidation on sea salt aerosol to the fractionation factor for high pH oxidation shows HOCl contributed 29% of S(IV) oxidation on sea salt in the short experimental timescale, highlighting the potential importance of hypohalous acids in the marine environment. The sulfur isotope fractionation factors measured in this study allow differentiation between the alkalinity-limited pathways - oxidation by O3 and by Cl catalysis (α34 = 1.0163±0.0018 at 19 °C in pure water or 1.0199±0.0024 at pH = 7.2) - which favour the heavy isotope, and the alkalinity non

  4. The Asian Tropopause Aerosol Layer Through Satellite and Balloon-Borne Measurements Combined With Modeling Approaches

    NASA Technical Reports Server (NTRS)

    Vernier, J.-P.; Fairlie, T. D.; Natarajan, M.; Wegner, T.; Baker, N.; Crawford, J.; Moore, J.; Deshler, T.; Gadhavi, H.; Jayaraman, A.; Pandit, A.; Raj, A.; Kumar, H.; Kumar, S.; Singh, A.; Vignelles, D.; Stenchikov, G.; Wiehold, F.; Bian, J.

    2016-01-01

    The Asian Tropopause Aerosol Layer-ATAL is a confined area of enhanced aerosol associated Summer Asia Monsoon spanning from the E. Med Sea to W. China. It essentially extends from top of convective outflow over much of SE Asia Existence recognize through CALIPSO observations.

  5. MODIS 3km Aerosol Product: Algorithm and Global Perspective

    NASA Technical Reports Server (NTRS)

    Remer, L. A.; Mattoo, S.; Levy, R. C.; Munchak, L.

    2013-01-01

    After more than a decade of producing a nominal 10 km aerosol product based on the dark target method, the MODIS aerosol team will be releasing a nominal 3 km product as part of their Collection 6 release. The new product differs from the original 10 km product only in the manner in which reflectance pixels are ingested, organized and selected by the aerosol algorithm. Overall, the 3 km product closely mirrors the 10 km product. However, the finer resolution product is able to retrieve over ocean closer to islands and coastlines, and is better able to resolve fine aerosol features such as smoke plumes over both ocean and land. In some situations, it provides retrievals over entire regions that the 10 km product barely samples. In situations traditionally difficult for the dark target algorithm, such as over bright or urban surfaces the 3 km product introduces isolated spikes of artificially high aerosol optical depth (AOD) that the 10 km algorithm avoids. Over land, globally, the 3 km product appears to be 0.01 to 0.02 higher than the 10 km product, while over ocean, the 3 km algorithm is retrieving a proportionally greater number of very low aerosol loading situations. Based on collocations with ground-based observations for only six months, expected errors associated with the 3 km land product are determined to be greater than for the 10 km product: 0.05 0.25 AOD. Over ocean, the suggestion is for expected errors to be the same as the 10 km product: 0.03 0.05 AOD. The advantage of the product is on the local scale, which will require continued evaluation not addressed here. Nevertheless, the new 3 km product is expected to provide important information complementary to existing satellite-derived products and become an important tool for the aerosol community.

  6. Passive remote sensing of aerosol layer height using near-UV multiangle polarization measurements

    NASA Astrophysics Data System (ADS)

    Wu, Lianghai; Hasekamp, Otto; Diedenhoven, Bastiaan; Cairns, Brian; Yorks, John E.; Chowdhary, Jacek

    2016-08-01

    We demonstrate that multiangle polarization measurements in the near-UV and blue part of the spectrum are very well suited for passive remote sensing of aerosol layer height. For this purpose we use simulated measurements with different setups (different wavelength ranges, with and without polarization, different polarimetric accuracies) as well as airborne measurements from the Research Scanning Polarimeter (RSP) obtained over the continental USA. We find good agreement of the retrieved aerosol layer height from RSP with measurements from the Cloud Physics Lidar showing a mean absolute difference of less than 1 km. Furthermore, we found that the information on aerosol layer height is provided for large part by the multiangle polarization measurements with high accuracy rather than the multiangle intensity measurements. The information on aerosol layer height is significantly decreased when the shortest RSP wavelength (410 nm) is excluded from the retrieval and is virtually absent when 550 nm is used as shortest wavelength.

  7. Complex measurements of aerosol and ion characteristics in the atmospheric boundary layer

    NASA Astrophysics Data System (ADS)

    Kikas, Iu. E.; Kolomiets, S. M.; Kornienko, V. I.; Mirme, A. A.; Sal'm, Ia. I.; Sergeev, I. Ia.; Tammet, Kh. F.

    Results of a comprehensive study of the characteristics of atmospheric ions and aerosols in the boundary layer during the summer season are reported. A study is also made of the kinetics of aerosol formation under conditions of high artificial ionization of the air by alpha and UV radiation. A high degree of correlation is shown to exist between atmospheric concentrations of medium ions and fine (less than 0.01 micron) aerosol. The results obtained support the radiation-chemical mechanism of aerosol formation.

  8. Lidar observations of the Pinatubo aerosol layer at Thule, Greenland

    SciTech Connect

    Di Girolamo, P.; Cacciani, M.; Sarra, A. di; Fiocco, G.; Fua, D. )

    1994-06-22

    This paper summarizes lidar measurements from Thule Greenland made during EASOE. The lidar was able to track aerosols, primarily of volcanic origin, through the winter. Above 18 km the aerosol content was strongly dependent upon the location of the vortex, and did not show a substantial increase until the vortex broke up.

  9. Evaluation of the operational Aerosol Layer Height retrieval algorithm for Sentinel-5 Precursor: application to O2 A band observations from GOME-2A

    NASA Astrophysics Data System (ADS)

    Sanders, A. F. J.; de Haan, J. F.; Sneep, M.; Apituley, A.; Stammes, P.; Vieitez, M. O.; Tilstra, L. G.; Tuinder, O. N. E.; Koning, C. E.; Veefkind, J. P.

    2015-06-01

    An algorithm setup for the operational Aerosol Layer Height product for TROPOMI on the Sentinel-5 Precursor mission is described and discussed, applied to GOME-2A data, and evaluated with lidar measurements. The algorithm makes a spectral fit of reflectance at the O2 A band in the near-infrared and the fit window runs from 758 to 770 nm. The aerosol profile is parameterized by a scattering layer with constant aerosol volume extinction coefficient and aerosol single scattering albedo and with a fixed pressure thickness. The algorithm's target parameter is the height of this layer. In this paper, we apply the algorithm to observations from GOME-2A in a number of systematic and extensive case studies and we compare retrieved aerosol layer heights with lidar measurements. Aerosol scenes cover various aerosol types, both elevated and boundary layer aerosols, and land and sea surfaces. The aerosol optical thicknesses for these scenes are relatively moderate. Retrieval experiments with GOME-2A spectra are used to investigate various sensitivities, in which particular attention is given to the role of the surface albedo. From retrieval simulations with the single-layer model, we learn that the surface albedo should be a fit parameter when retrieving aerosol layer height from the O2 A band. Current uncertainties in surface albedo climatologies cause biases and non-convergences when the surface albedo is fixed in the retrieval. Biases disappear and convergence improves when the surface albedo is fitted, while precision of retrieved aerosol layer pressure is still largely within requirement levels. Moreover, we show that fitting the surface albedo helps to ameliorate biases in retrieved aerosol layer height when the assumed aerosol model is inaccurate. Subsequent retrievals with GOME-2A spectra confirm that convergence is better when the surface albedo is retrieved simultaneously with aerosol parameters. However, retrieved aerosol layer pressures are systematically low (i

  10. Evaluation of the operational Aerosol Layer Height retrieval algorithm for Sentinel-5 Precursor: application to O2 A band observations from GOME-2A

    NASA Astrophysics Data System (ADS)

    Sanders, A. F. J.; de Haan, J. F.; Sneep, M.; Apituley, A.; Stammes, P.; Vieitez, M. O.; Tilstra, L. G.; Tuinder, O. N. E.; Koning, C. E.; Veefkind, J. P.

    2015-11-01

    An algorithm setup for the operational Aerosol Layer Height product for TROPOMI on the Sentinel-5 Precursor mission is described and discussed, applied to GOME-2A data, and evaluated with lidar measurements. The algorithm makes a spectral fit of reflectance at the O2 A band in the near-infrared and the fit window runs from 758 to 770 nm. The aerosol profile is parameterised by a scattering layer with constant aerosol volume extinction coefficient and aerosol single scattering albedo and with a fixed pressure thickness. The algorithm's target parameter is the height of this layer. In this paper, we apply the algorithm to observations from GOME-2A in a number of systematic and extensive case studies, and we compare retrieved aerosol layer heights with lidar measurements. Aerosol scenes cover various aerosol types, both elevated and boundary layer aerosols, and land and sea surfaces. The aerosol optical thicknesses for these scenes are relatively moderate. Retrieval experiments with GOME-2A spectra are used to investigate various sensitivities, in which particular attention is given to the role of the surface albedo. From retrieval simulations with the single-layer model, we learn that the surface albedo should be a fit parameter when retrieving aerosol layer height from the O2 A band. Current uncertainties in surface albedo climatologies cause biases and non-convergences when the surface albedo is fixed in the retrieval. Biases disappear and convergence improves when the surface albedo is fitted, while precision of retrieved aerosol layer pressure is still largely within requirement levels. Moreover, we show that fitting the surface albedo helps to ameliorate biases in retrieved aerosol layer height when the assumed aerosol model is inaccurate. Subsequent retrievals with GOME-2A spectra confirm that convergence is better when the surface albedo is retrieved simultaneously with aerosol parameters. However, retrieved aerosol layer pressures are systematically low (i

  11. Recent Improvements to CALIOP Level 3 Aerosol Profile Product for Global 3-D Aerosol Extinction Characterization

    NASA Astrophysics Data System (ADS)

    Tackett, J. L.; Getzewich, B. J.; Winker, D. M.; Vaughan, M. A.

    2015-12-01

    With nine years of retrievals, the CALIOP level 3 aerosol profile product provides an unprecedented synopsis of aerosol extinction in three dimensions and the potential to quantify changes in aerosol distributions over time. The CALIOP level 3 aerosol profile product, initially released as a beta product in 2011, reports monthly averages of quality-screened aerosol extinction profiles on a uniform latitude/longitude grid for different cloud-cover scenarios, called "sky conditions". This presentation demonstrates improvements to the second version of the product which will be released in September 2015. The largest improvements are the new sky condition definitions which parse the atmosphere into "cloud-free" views accessible to passive remote sensors, "all-sky" views accessible to active remote sensors and "cloudy-sky" views for opaque and transparent clouds which were previously inaccessible to passive remote sensors. Taken together, the new sky conditions comprehensively summarize CALIOP aerosol extinction profiles for a broad range of scientific queries. In addition to dust-only extinction profiles, the new version will include polluted-dust and smoke-only extinction averages. A new method is adopted for averaging dust-only extinction profiles to reduce high biases which exist in the beta version of the level 3 aerosol profile product. This presentation justifies the new averaging methodology and demonstrates vertical profiles of dust and smoke extinction over Africa during the biomass burning season. Another crucial advancement demonstrated in this presentation is a new approach for computing monthly mean aerosol optical depth which removes low biases reported in the beta version - a scenario unique to lidar datasets.

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

    SciTech Connect

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

    2005-03-18

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

  13. Toxicity of aerosols of sodium reaction products.

    PubMed

    Zwicker, G M; Allen, M D; Stevens, D L

    1979-01-01

    Sodium is used as the heat transfer medium in several new energy technologies such as liquid-metal fast-breeder reactors and solar-thermal collection systems. Because sodium burns in air and reacts violently with water, the potential exists for an airborne release of sodium combustion products and subsequent human exposure. To help evaluate the potential short-term hazard from an accidental sodium fire, male juvenile or adult Wistar rats were exposed to sodium aerosols for 2 hours to determine the dose at which 50 percent of the animals were affected (ED50) for each age group. The estimated ED50 of 510 microgram/l for adults was not significantly different from the estimated ED50 of 489 microgram/l for juveniles. The incidence of acute laryngitis, attributed to exposure, was three times higher for juvenile rats than for adults, and the degree of severity of this lesion was significantly (P less than 0.05) higher for juveniles.

  14. Tropospheric ozone and aerosols measured by airborne lidar during the 1988 Arctic boundary layer experiment

    NASA Technical Reports Server (NTRS)

    Browell, Edward V.; Butler, Carolyn F.; Kooi, Susan A.

    1991-01-01

    Ozone (O3) and aerosol distributions were measured from an aircraft using a differential absorption lidar (DIAL) system as part of the 1988 NASA Global Tropospheric Experiment - Arctic Boundary Layer Experiment (ABLE-3A) to study the sources and sinks of gases and aerosols over the tundra regions of Alaska during the summer. The tropospheric O3 budget over the Arctic was found to be strongly influenced by stratospheric intrusions. Regions of low aerosol scattering and enhanced O3 mixing ratios were usually correlated with descending air from the upper troposphere or lower stratosphere. Several cases of continental polar air masses were examined during the experiment. The aerosol scattering associated with these air masses was very low, and the atmospheric distribution of aerosols was quite homogeneous for those air masses that had been transported over the ice for greater than or = 3 days. The transition in O3 and aerosol distributions from tundra to marine conditions was examined several times. The aerosol data clearly show an abrupt change in aerosol scattering properties within the mixed layer from lower values over the tundra to generally higher values over the water. The distinct differences in the heights of the mixed layers in the two regions was also readily apparent. Several cases of enhanced O3 were observed during ABLE-3 in conjunction with enhanced aerosol scattering in layers in the free atmosphere. Examples are presented of the large scale variations of O3 and aerosols observed with the airborne lidar system from near the surface to above the tropopause over the Arctic during ABLE-3.

  15. 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

  16. Validations of GOES-R ABI Aerosol Products

    NASA Astrophysics Data System (ADS)

    Ciren, P.; Laszlo, I.; Kondragunta, S.; Liu, H.; Zhou, M.

    2009-12-01

    High temporal resolution observations from geostationary platform provide unique benefits for monitoring the development of air pollution event. Especially, observations of multi-visible channels in the future GOES-R ABI provide more capability for characterizing air quality. GOES-R ABI Air Quality products include Aerosol detection product and suspended matter/AOD product. The first one is to detect the presence of smoke/dust; the second one is to quantify the amount of particles in the air in terms of light attenuation, and consequently inferred concentration of particles. In this presentation, we focus on the demonstration of the performance of the developed products through a comprehensive validation process. In the current pre-launch stage, MODIS radiances at bands similar to those of ABI are used as proxy. As for the suspended matter/AOD product, truth data include observations from ground-based instruments at the AERONET stations, MODIS collection 5 aerosol products, and aerosol product from CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation). For aerosol detection product, truth data include MODIS RGB images and CALIPO Vertical Feature Mask Products. Through comparisons with global observations from MODIS, point observations from AERONET, and narrow-track observations from CALIPSO, accuracy and precision (for AOD only) are evaluated for both products. In addition, a validation system which includes not only the evaluation with historical data, but also monitoring the products qualities with near-real time observations, is presented.

  17. 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.

  18. The persistently variable "background" stratospheric aerosol layer and global climate change.

    PubMed

    Solomon, S; Daniel, J S; Neely, R R; Vernier, J-P; Dutton, E G; Thomason, L W

    2011-08-12

    Recent measurements demonstrate that the "background" stratospheric aerosol layer is persistently variable rather than constant, even in the absence of major volcanic eruptions. Several independent data sets show that stratospheric aerosols have increased in abundance since 2000. Near-global satellite aerosol data imply a negative radiative forcing due to stratospheric aerosol changes over this period of about -0.1 watt per square meter, reducing the recent global warming that would otherwise have occurred. Observations from earlier periods are limited but suggest an additional negative radiative forcing of about -0.1 watt per square meter from 1960 to 1990. Climate model projections neglecting these changes would continue to overestimate the radiative forcing and global warming in coming decades if these aerosols remain present at current values or increase.

  19. Radiative Impact of Observed and Simulated Aerosol Layers Over the East Coast of North America

    NASA Astrophysics Data System (ADS)

    Berg, L. K.; Fast, J. D.; Burton, S. P.; Chand, D.; Comstock, J. M.; Ferrare, R. A.; Hair, J. W.; Hostetler, C. A.; Hubbe, J. M.; Kassianov, E.; Rogers, R. R.; Sedlacek, A. J., III; Shilling, J. E.; Tomlinson, J. M.; Wilson, J. M.; Zelenyuk, A.

    2014-12-01

    The vertical distribution of particles in the atmospheric column can have a large impact on the radiative forcing and cloud microphysics. A recent climatology constructed using data collected by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) suggests elevated layers of aerosol are quite common near the North American east coast during both winter and summer. The Two-Column Aerosol Project (TCAP), conducted from June 2012 through June 2013, was a unique study utilizing both in situ and remotely sensed measurements designed to provide a comprehensive data set that can be used to investigate science questions related to aerosol radiative forcing and the vertical distribution of aerosol. The study sampled the atmosphere at a number of altitudes within two atmospheric columns; one located near the coast of North America (over Cape Cod, MA) and a second over the Atlantic Ocean several hundred kilometers from the coast. TCAP included the yearlong deployment of the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) located at the base of the Cape Cod column, as well as summer and winter aircraft intensive observation periods (IOPs) using the ARM Aerial Facility. One important finding from the TCAP summer IOP is the relatively common occurrence (during four of the six nearly cloud-free flights) of elevated aerosol layers in both the Cape Cod and maritime columns that were detected using the nadir pointing second-generation NASA Langley Research Center High-Spectral Resolution Lidar (HSRL-2). These elevated layers contributed up to 60% of the total observed aerosol optical depth (AOD). Many of these layers were also intercepted by the aircraft configured for in situ sampling, and the aerosol in the layers was found to have increased amounts of biomass burning material and nitrate compared to aerosol found near the surface. Both the in situ and remote sensing observations have been compared to

  20. Organic Aerosol Component (OACOMP) Value-Added Product Report

    SciTech Connect

    Fast, J; Zhang, Q; Tilp, A; Shippert, T; Parworth, C; Mei, F

    2013-08-23

    Significantly improved returns in their aerosol chemistry data can be achieved via the development of a value-added product (VAP) of deriving OA components, called Organic Aerosol Components (OACOMP). OACOMP is primarily based on multivariate analysis of the measured organic mass spectral matrix. The key outputs of OACOMP are the concentration time series and the mass spectra of OA factors that are associated with distinct sources, formation and evolution processes, and physicochemical properties.

  1. Characterizing interactions between aerosols and cloud droplets in marine boundary layer clouds

    NASA Astrophysics Data System (ADS)

    Andersen, Hendrik; Cermak, Jan

    2016-04-01

    This contribution presents a method to characterize the nonlinearities of interactions between aerosols and cloud droplets in marine boundary layer clouds based on global MODIS observations. Clouds play a crucial role in the climate system as their radiative properties and precipitation patterns significantly impact the Earth's energy balance. Cloud properties are determined by environmental conditions, as cloud formation requires the availability of water vapour ("precipitable water") and condensation nuclei in sufficiently saturated conditions. The ways in which aerosols as condensation nuclei in particular influence the optical, micro- and macrophysical properties of clouds are one of the largest remaining uncertainties in climate-change research. In particular, cloud droplet size is believed to be impacted, and thereby cloud reflectivity, lifetime, and precipitation susceptibility. However, the connection between aerosols and cloud droplets is nonlinear, due to various factors and processes. The impact of aerosols on cloud properties is thought to be strongest with low aerosol loadings, whereas it saturates with high aerosol loadings. To gain understanding of the processes that govern low cloud water properties in order to increase accuracy of climate models and predictions of future changes in the climate system is thus of great importance. In this study, global Terra MODIS L3 data sets are used to characterize the nonlinearities of the interactions between aerosols and cloud droplets in marine boundary layer clouds. MODIS observations are binned in classes of aerosol loading to identify at what loading aerosol impact on cloud droplets is the strongest and at which loading it saturates. Results are connected to ERA-Interim and MACC data sets to identify connections of detected patterns to meteorology and aerosol species.

  2. Transport and Evolution of Aerosol Above/Below the Boundary Layer in the Western Mediterranean Basin

    NASA Astrophysics Data System (ADS)

    Roberts, G. C.; Corrigan, C.; Ritchie, J.; Pont, V.; Claeys, M.; Sciare, J.; Mallet, M.; Dulac, F.

    2014-12-01

    The Mediterranean Region has been identified as sensitive to changes in the hydrological cycle, which could affect the water resources for millions of people by the turn of the century. However, prior to recent observations, most climate models have not accounted for the impacts of aerosol in this region. Past airborne studies have shown that aerosol sources from Europe and Africa are often transported throughout the lower troposphere; yet, because of their complex vertical distribution, it is a challenge to capture the variability and quantify the contribution of these sources to the radiative budget and precipitation processes. The PAEROS ChArMEx Mountain Experiment (PACMEx) complemented the regional activities of the ChArMEx/ADRIMED summer 2013 campaign by collecting aerosol data from atop a mountain on the island of Corsica, France in order to assess boundary layer / free troposphere atmospheric processes. In June/July 2013, PACMEx instruments were deployed at 2000 m.asl near the center of Corsica to complement ground-based aerosol observations at 550 m.asl on the northern peninsula, as well as airborne measurements. Comparisons between the peninsula site and the mountain site show similar general trends in aerosol properties; yet, differences in aerosol properties reveal the myriad transport mechanisms over the Mediterranean Basin. Using aerosol physicochemical data coupled with back trajectory analysis, different sources have been identified including Saharan dust transport, residual dust mixed with sea salt, anthropogenic emissions from Western Europe, and a period of biomass burning from Eastern Europe. Each period exhibits distinct signatures in the aerosol related to transport processes above and below the boundary layer. In addition, the total aerosol concentrations at the mountain site revealed a strong diurnal cycling between the atmospheric boundary layer and the free troposphere, which is typical of mountain-top observations. PACMEx was funded by the

  3. Interaction between the aerosol direct effect in the lower troposphere and the planetary boundary layer depth

    NASA Astrophysics Data System (ADS)

    Sawyer, Virginia Ruth

    The planetary boundary layer (PBL) limits the vertical mixing of aerosol emitted to the lower troposphere. The PBL depth and its change over time affect weather, surface air quality and radiative forcing. While model simulations have suggested that the column optical properties of aerosol are associated with changes in the PBL depth in turn, there are few long-term measurements of PBL depth with which to validate the theory. Of the existing methods to detect the PBL depth from atmospheric profiles, many require supporting information from multiple instruments or cannot adapt to changing atmospheric conditions. This study combines two common methods for PBL depth detection (wavelet covariance and iterative curve-fitting) in order to produce more reliable PBL depths for micropulse lidar backscatter (MPL). The combined algorithm is also flexible enough to use with radiosonde and atmospheric emitted radiance interferometer (AERI) data. PBL depth retrievals from these three instruments collected at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site are compared to one another to show the robustness of the algorithm. The comparisons were made for different times of day, four seasons, and variable sky conditions. While considerable uncertainties exist in PBL detection using all three types of measurements, the agreement among the PBL products is promising, and the different measurements have complementary advantages. The best agreement in the seasonal cycle occurs in winter, and the best agreement in the diurnal cycle when the boundary-layer regime is mature and changes slowly. PBL depths from instruments with higher temporal resolution (MPL and AERI) are of comparable accuracy to radiosonde-derived PBL depths. The new PBL depth measurements for SGP are compared to MPL-derived PBL depths from a multiyear lidar deployment at the Hefei Radiation Observatory (HeRO), and the column aerosol optical depth (AOD) for each site is considered. A one

  4. Production of Highly Charged Pharmaceutical Aerosols Using a New Aerosol Induction Charger

    PubMed Central

    Golshahi, Laleh; Longest, P. Worth; Holbrook, Landon; Snead, Jessica; Hindle, Michael

    2015-01-01

    Purpose Properly charged particles can be used for effective lung targeting of pharmaceutical aerosols. The objective of this study was to characterize the performance of a new induction charger that operates with a mesh nebulizer for the production of highly charged submicrometer aerosols to bypass the mouth-throat and deliver clinically relevant doses of medications to the lungs. Methods Variables of interest included combinations of model drug (i.e. albuterol sulfate) and charging excipient (NaCl) as well as strength of the charging field (1–5 kV/cm). Aerosol charge and size were measured using a modified electrical low pressure impactor system combined with high performance liquid chromatography. Results At the approximate mass median aerodynamic diameter (MMAD) of the aerosol (~ 0.4 μm), the induction charge on the particles was an order of magnitude above the field and diffusion charge limit. The nebulization rate was 439.3 ± 42.9 μl/min, which with a 0.1 % w/v solution delivered 419.5 ± 34.2 μg of medication per minute. A new correlation was developed to predict particle charge produced by the induction charger. Conclusions The combination of the aerosol induction charger and predictive correlations will allow for the practical generation and control of charged submicrometer aerosols for targeting deposition within the lungs. PMID:25823649

  5. Aircraft Observations of Marine Aerosol Properties in the Presence of Boundary Layer Rolls

    NASA Astrophysics Data System (ADS)

    Kapustin, V.; Clarke, A.; Howell, S.; Conley, S.; Faloona, I.; Brekhovskikh, V.; McNaughton, C.

    2008-12-01

    The Hawaii Group for Environmental Aerosol Research deployed a wide range of airborne aerosol instrumentation as part of MILAGRO/INTEX (2006) and PASE (2007) experiments. 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). The measurements revealed frequently observed presence of numerous periodic structures related both to horizontal convective rolls (HCRs) and Kelvin-Helmholtz instability (KHI). HCRs, commonly formed when some vertical wind shear is present, are significant to the vertical transport of momentum, heat, moisture, and air pollutant including aerosols within the boundary layer. KHIs, occurred in areas of enhanced velocity shear and/or a local minimum of static stability, contribute strongly to the dissipation of large-scale motions into turbulence. This presentation focused on the direct in-situ marine aerosol properties in the presence of BL rolls by providing evidence that the observed variations are caused by rolls. We also studied whether the presence of rolls leads to the enhancement of aerosol fluxes. We have investigated roll structures in diverse MBL settings and have demonstrated that these can play an active role in the redistribution of aerosol, gas and water vapor in the MBL. Depending upon the thermodynamic profiles and the roll size, altitude, temporal duration these rolls can have a marked effect on the exchange of air masses between the buffer layer, the surface mixed layer and the free troposphere. This will lead to changes in the horizontal extinction in these layers relative to regions not influenced by the rolls. Hence, the evolution of aerosol optical properties in the near-surface mixed layer will be affected by rolls and the conditions that stimulate them. These can occur with or without associated cloud features. Some ongoing studies include the following

  6. The Asian Tropopause Aerosol layer through satellite and balloon-borne measurements combined with modelling approaches.

    NASA Astrophysics Data System (ADS)

    Vernier, J. P.; Fairlie, T. D.; Natarajan, M.; Crawford, J. H.; Baker, N. C.; Wegner, T.; Deshler, T.; Gadhavi, H. S.; Kumar, S.; Singh, A. K.; Jayaraman, A.; Raj, A.; Alladi, H.; Ratnam, M. V.; Pandit, A.; Vignelles, D.; Wienhold, F.; Liu, H.; Kumar, S.

    2015-12-01

    The Asian tropopause Aerosol Layer (ATAL) is a seasonal aerosol feature occurring in the Upper Troposphere and Lower Stratosphere (UTLS) above Asia during the Summer Asian Monsoon. Vertically resolved aerosol backscatter profiles from the Cloud-Aerosol Lidar and Infrared Pathfinder satellite Observation (CALIPSO) mission and extinction profiles from the Stratospheric Aerosol and Gas Experiment (SAGE) have been used to infer the spatial and temporal distributions of the ATAL since the late 90's. We found that aerosol optical thickness between 13-18km have increased by a factor of 2-3 over the past 16 years likely related to raising pollution levels in South East Asia occuring during the same period. Modelling studies of the ATAL using WACCAM 3 and GEOS-Chem have provided conflicting information on its origin and a better representation of in-cloud SO2 and aerosol lifetime in GOES-Chem seems to be key to obtain consistent results with the few SO2 measurements available in the UTLS during the Asian Monsoon. In situ measurements of aerosol and trace gases in the UTLS from several balloon campaigns which took place in summer 2014 and 2015 in Asia will be presented and discussed with combined satellite and modelling analysis.

  7. A New Stratospheric Aerosol Product from CALIPSO Lidar Measurements

    NASA Astrophysics Data System (ADS)

    Kar, J.; Vaughan, M.; Trepte, C. R.; Winker, D. M.; Vernier, J. P.; Pitts, M. C.; Young, S. A.; Liu, Z.; Lucker, P.; Tackett, J. L.; Omar, A. H.

    2014-12-01

    Stratospheric aerosols are derived from precursor SO2 and OCS gases transported from the lower troposphere. Volcanic injections can also enhance aerosol loadings far above background levels. The latter can exert a significant influence on the Earth's radiation budget for major and even minor eruptions. Careful measurements are needed, therefore, to monitor the distribution and evolution of stratospheric aerosols for climate related studies. The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission has been acquiring profile measurements of clouds and aerosols since 2006, leading to major advances in our understanding of tropospheric aerosol and cloud properties and the processes that control them. The CALIPSO products have also enabled new insights into polar stratospheric clouds and stratospheric aerosols. Vernier et al (2009,JGR,114,D00H10) reported on the construction of a modified CALIPSO lidar product that corrected minor artifacts with the original lidar calibration that affected stratospheric aerosol investigations. A significantly improved CALIPSO Lidar Version 4 Level 1 product has been recently released addressing these calibration issues and has resulted in enhanced signal levels and a highly stable record over the span of the mission. Based on this product, a new 3D gridded stratospheric CALIPSO data product is under development and being targeted for release in 2015. A key emphasis of this new product is to bridge the measurement gap between the SAGE II and SAGE III data record (1984-2005) and the start of measurements from the new SAGE III instrument to be deployed on the International Space Station in 2016. The primary parameters delivered in the CALIPSO stratospheric data products will be attenuated scattering ratio and aerosol extinction profiles, both averaged over one month intervals and binned into an equal angle grid of constant latitude and longitude with a vertical resolution of 900m. We will present the overall

  8. Aerosol dynamics in the equatorial Pacific Marine boundary layer: Microphysics, diurnal cycles and entertainment

    SciTech Connect

    Clarke, A D; Litchy, M; Li, Z

    1996-04-01

    During July-August of 1994 the authors measured the size resolved physiochemical properties of aerosol particles at Christmas Island in the equatorial Pacific. In spite of rapid diurnal conversion of dimethylsulfide (DMS) to sulfur dioxide (SO{sub 2}) the authors found no evidence for new particle production in the marine boundary layer (MBL) and more than 95% of all particles were consistently larger than 0.02{mu}m diameter, indicating an aged aerosol number (size-distribution) was bimodal with peaks near 0.05{mu}m and 0.2{mu}m particle diameter (D{sub p}) and had a cloud-processed intermode minimum at about 0.09{mu}m that varied in phase with diurnal changes in ozone concentration. This suggests that the number distribution for condensation nuclei (CN) and cloud condensation (CCN) was maintained by a quasiequilibrium between entrainment (estimated to be 0.6{+-}0.2 cm s{sup {minus}1}) from sources aloft and processes in the MBL. This implies a replenishment timescale for nuclei of about 2 and 4 days for this region. The stability of the distribution and the 0.09{mu}m cloud processed minima suggests trade winds cumulus supersaturations near 0.35% and updrafts near 1 m s{sup {minus}1}. 17 refs., 4 fig., 1 tab.

  9. Organic Aerosol Component (OACOMP) Value-Added Product

    SciTech Connect

    Fast, J; Zhang, Q; tilp, A; Shippert, T; Parworth, C; Mei, F

    2013-08-23

    Organic aerosol (OA, i.e., the organic fraction of particles) accounts for 10–90% of the fine aerosol mass globally and is a key determinant of aerosol radiative forcing. But atmospheric OA is poorly characterized and its life cycle insufficiently represented in models. As a result, current models are unable to simulate OA concentrations and properties accurately. This deficiency represents a large source of uncertainty in quantification of aerosol effects and prediction of future climate change. Evaluation and development of aerosol models require data products generated from field observations. Real-time, quantitative data acquired with aerosol mass spectrometers (AMS) (Canagaratna et al. 2007) are critical to this need. The AMS determines size-resolved concentrations of non-refractory (NR) species in submicrometer particles (PM1) with fast time resolution suitable for both ground-based and aircraft deployments. The high-resolution AMS (HR-AMS), which is equipped with a high mass resolution time-of-flight mass spectrometer, can be used to determine the elemental composition and oxidation degrees of OA (DeCarlo et al. 2006).

  10. High Spectral Resolution Lidar (HSRL)-2 Observations of Aerosol Variability and Mixing during Boundary Layer Evolution in Houston

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Scarino, A. J.; Rogers, R. R.; Hostetler, C. A.; Ferrare, R. A.; Sawamura, P.; Berkoff, T.; Harper, D. B.; Cook, A. L.; Saide, P. E.

    2014-12-01

    The NASA Langley airborne multi-wavelength High Spectral Resolution Lidar (HSRL-2) provides the vertical distribution of aerosol optical properties as "curtains" of aerosol extinction, backscatter and depolarization along the flight track, plus intensive properties that are used to infer aerosol type and external mixing of types. Deployed aboard the NASA Langley King Air on the DISCOVER-AQ field mission in Houston in September 2013, HSRL-2 flew a pattern that included 18 ground sites, repeated four times a day, coordinated with a suite of airborne in situ measurements. The horizontally and vertically resolved curtains of HSRL-2 measurements give an unparalleled view of the spatial and temporal variability of aerosol, which provide broad context for interpreting other measurements and models. In Houston, HSRL-2 generally observed significant variability with distinct layering: boundary layer, residual layer, and frequent upper layers of smoke transported from the Mississippi Valley. The period from Sep. 11-14 is notable for a large aerosol build-up and persistent layers in the free troposphere. We investigate the aerosol properties and evolution using the vertically resolved HSRL-2 measurements, typing and mixture analysis techniques, and boundary layer detection. Between morning and afternoon overpasses, as the boundary layer grows, many distinctions between the layers are lost as the aerosols become mixed. As the boundary layer collapses overnight, the aerosols are cut off and are observed in a distinct residual layer the following morning. HSRL-2 measurements of the upper smoke layers suggest slightly different properties each day as new smoke enters the region, while the morning boundary layer indicates more similarity in local emissions day-to-day. HSRL-2 intensive variables (indicators of aerosol type) reflect complex yet predictable mixing. We will present the analysis of aerosol mixtures, and explore the WRF-Chem chemical transport model along the HSRL-2

  11. Clouds, Aerosol, and Precipitation in the Marine Boundary Layer: An ARM Mobile Facility Deployment

    NASA Technical Reports Server (NTRS)

    Wood, Robert; Wyant, Matthew; Bretherton, Christopher S.; Remillard, Jasmine; Kollias, Pavlos; Fletcher, Jennifer; Stemmler, Jayson; de Szoeke, Simone; Yuter, Sandra; Miller, Matthew; Mechem, David; Tselioudis, George; Chiu, J. Christine; Mann, Julian A. L.; O'Connor, Ewan J.; Hogan, Robin J.; Dong, Xiquan; Miller, Mark; Ghate, Virendra; Jefferson, Anne; Min, Qilong; Minnis, Patrick; Palikonda, Rabindra; Albrecht, Bruce; Luke, Ed; Hannay, Cecile; Lin, Yanluan

    2015-01-01

    Capsule: A 21-month deployment to Graciosa Island in the northeastern Atlantic Ocean is providing an unprecedented record of the clouds, aerosols and meteorology in a poorly-sampled remote marine environment The Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) deployment at Graciosa Island in the Azores generated a 21 month (April 2009- December 2010) comprehensive dataset documenting clouds, aerosols and precipitation using the Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF). The scientific aim of the deployment is to gain improved understanding of the interactions of clouds, aerosols and precipitation in the marine boundary layer. Graciosa Island straddles the boundary between the subtropics and midlatitudes in the Northeast Atlantic Ocean, and consequently experiences a great diversity of meteorological and cloudiness conditions. Low clouds are the dominant cloud type, with stratocumulus and cumulus occurring regularly. Approximately half of all clouds contained precipitation detectable as radar echoes below the cloud base. Radar and satellite observations show that clouds with tops from 1- 11 km contribute more or less equally to surface-measured precipitation at Graciosa. A wide range of aerosol conditions was sampled during the deployment consistent with the diversity of sources as indicated by back trajectory analysis. Preliminary findings suggest important two-way interactions between aerosols and clouds at Graciosa, with aerosols affecting light precipitation and cloud radiative properties while being controlled in part by precipitation scavenging. The data from at Graciosa are being compared with short-range forecasts made a variety of models. A pilot analysis with two climate and two weather forecast models shows that they reproduce the observed time-varying vertical structure of lower-tropospheric cloud fairly well, but the cloud-nucleating aerosol concentrations less well. The Graciosa site has been chosen to be a

  12. New evidence of an organic layer on marine aerosols

    NASA Astrophysics Data System (ADS)

    Tervahattu, Heikki; Hartonen, Kari; Kerminen, Veli-Matti; Kupiainen, Kaarle; Aarnio, Päivi; Koskentalo, Tarja; Tuck, Adrian F.; Vaida, Veronica

    2002-04-01

    An extraordinary episode of fine particles (diameter mainly <2.5 μm) occurred in Helsinki, southern Finland, at the end of February 1998. The air masses came from the North Atlantic Ocean and passed over France, Germany, and southern Scandinavia. Particles were collected during the episode as well as before and after it. Uncoated particle samples were adhered to an indium substrate and were studied by a scanning electron microscope (SEM) coupled with an energy dispersive X-ray microanalyzer (EDX). A great proportion of the particles behaved differently than aerosols previously studied by microscopic techniques. The particles (size mainly 0.5-1 μm) did not exhibit solid shape. They were ``bubbling'' or ``pulsating'' continually, enlarging in one part and shrinking in another. Some particles were broken down, especially when the beam of the electron microscope was focused on them. EDX analyses showed that the particles contained much carbon together with oxygen, sulfur, and sodium. Ion analyses by ion chromatography revealed high concentrations of sodium, sulfate, nitrate, and ammonium. The particles were identified as marine sea-salt aerosols, which had accumulated anthropogenic emissions and lost chloride during their flow through continental polluted air. The shape fluctuations and the high carbon content observed by SEM/EDX led to the conclusion that the aerosols were enclosed by an organic membrane. Direct insertion probe/mass spectrometry investigations showed remarkable amounts of fragmented aliphatic hydrocarbons, which were considered as an evidence of a lipid membrane on the surface of the particles. The impact of the posited organic film on the properties of sea-salt particles, as well as on Earth's climate, is discussed.

  13. DUAL ORIGIN OF AEROSOLS IN TITAN'S DETACHED HAZE LAYER

    SciTech Connect

    Cours, T.; Burgalat, J.; Rannou, P.; Rodriguez, S.; Brahic, A.

    2011-11-10

    We have analyzed scattered light profiles from the Cassini Imaging Science Subsystem, taken at the limb and at several large phase angles. We also used results from an occultation observed by Ultraviolet Imaging Spectrograph in the ultraviolet. We found that particles responsible for the scattering in the detached haze have an effective radius around 0.15 {mu}m and the aerosol size distribution follows a power law (exponent about -4.5). We discuss these results along with microphysical constraints and thermal equilibrium of the detached haze, and we conclude that only a strong interaction with atmospheric dynamics can explain such a structure.

  14. Lidar Investigations of Aerosol, Cloud, and Boundary Layer Properties Over the ARM ACRF Sites

    SciTech Connect

    Turner, David D.; Ferrare, Richard

    2015-01-13

    The systematic and routine measurements of aerosol, water vapor, and clouds in the vertical column above the Atmospheric Radiation Measurement (ARM) sites from surface-based remote sensing systems provides a unique and comprehensive data source that can be used to characterize the boundary layer (i.e., the lowest 3 km of the atmosphere) and its evolution. New algorithms have been developed to provide critical datasets from ARM instruments, and these datasets have been used in long-term analyses to better understand the climatology of water vapor and aerosol over Darwin, the turbulent structure of the boundary layer and its statistical properties over Oklahoma, and to better determine the distribution of ice and aerosol particles over northern Alaska.

  15. Elevated aerosol layers and their radiative impact over Kanpur during monsoon onset period

    NASA Astrophysics Data System (ADS)

    Sarangi, Chandan; Tripathi, S. N.; Mishra, A. K.; Goel, A.; Welton, E. J.

    2016-07-01

    Accurate information about aerosol vertical distribution is needed to reduce uncertainties in aerosol radiative forcing and its effect on atmospheric dynamics. The present study deals with synergistic analyses of aerosol vertical distribution and aerosol optical depth (AOD) with meteorological variables using multisatellite and ground-based remote sensors over Kanpur in central Indo-Gangetic Plain (IGP). Micro-Pulse Lidar Network-derived aerosol vertical extinction (σ) profiles are analyzed to quantify the interannual and daytime variations during monsoon onset period (May-June) for 2009-2011. The mean aerosol profile is broadly categorized into two layers viz., a surface layer (SL) extending up to 1.5 km (where σ decreased exponentially with height) and an elevated aerosol layer (EAL) extending between 1.5 and 5.5 km. The increase in total columnar aerosol loading is associated with relatively higher increase in contribution from EAL loading than that from SL. The mean contributions of EALs are about 60%, 51%, and 50% to total columnar AOD during 2009, 2010, and 2011, respectively. We observe distinct parabolic EALs during early morning and late evening but uniformly mixed EALs during midday. The interannual and daytime variations of EALs are mainly influenced by long-range transport and convective capacity of the local emissions, respectively. Radiative flux analysis shows that clear-sky incoming solar radiation at surface is reduced with increase in AOD, which indicates significant cooling at surface. Collocated analysis of atmospheric temperature and aerosol loading reveals that increase in AOD not only resulted in surface dimming but also reduced the temperature (˜2-3°C) of lower troposphere (below 3 km altitude). Radiative transfer simulations indicate that the reduction of incoming solar radiation at surface is mainly due to increased absorption by EALs (with increase in total AOD). The observed cooling in lower troposphere in high aerosol loading

  16. Current Status of Suomi NPP VIIRS Aerosol Products

    NASA Astrophysics Data System (ADS)

    Kondragunta, S.; Laszlo, I.; Liu, H.; Zhang, H.; Huang, J.; Remer, L. A.; Ciren, P.; Huang, H.

    2013-12-01

    The Suomi National Polar-orbiting Partnership (NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) instrument was launched on October 28, 2011. It provides Aerosol Optical Thickness (AOT) at two different spatial resolutions: a pixel level (~750 m at nadir) product called the Intermediate Product (IP) and an aggregated (~6 km at nadir) product called the Environmental Data Record (EDR). The VIIRS AOT is expected to provide continuity to the 10-km Aqua and Terra MODIS (Moderate resolution Imaging Spectroradiometer) AOT products that the air quality and public health community has been using. The VIIRS aerosol product suite also includes less mature products such as Suspended Matter (SM) and Aerosol Particle Size Parameter (APSP). An extensive validation of VIIRS best quality aerosol products with ground based L1.5 AERONET data shows that the AOT EDR product has an accuracy/precision of -0.01/0.11 and 0.01/0.08 over land and ocean respectively. Globally, VIIRS mean AOT EDR (0.20) is similar to Aqua MODIS (0.16) with some important regional and seasonal differences. Analysis of SM shows that the algorithm predominantly picks smoke both over land and ocean which is not in agreement with retrievals from Multi-angle Imaging SpectroRadiometer (MISR) and Cloud Aerosol Lidar and Infrared Pathfinder Space Observations (CALIPSO). Similarly, the Angstrom Exponent (AE) retrieval used as a proxy for particle size has no skill over land and only a marginal skill over ocean when compared to AERONET; although a bias of ~0.2 for over ocean retrievals meets specification (0.3), the correlation is low and the standard deviation is ~0.6 and does not meet specification (0.3). This evaluation places the VIIRS AOT product at the provisional maturity level (product is validated, may contain some errors, and ready for operational evaluation). However, several algorithm updates which include a better approach to retrieve surface reflectance are forthcoming. Current status of the aerosol

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

    NASA Astrophysics Data System (ADS)

    Wei, Chao; Su, Hang; Cheng, Yafang

    2016-04-01

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

  18. 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

  19. Aerosol Layering Characterization Near the Gobi Desert by a Double Polarization Lidar System

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Boselli, A.; Sannino, A.; Song, C.; Spinelli, N.; Wang, X.

    2016-06-01

    In order to carry out 4-D (space and time) analysis of the atmospheric aerosol distribution and to make a characterization of their properties and time evolution, a transportable multi-wavelength, Elastic/Raman scanning lidar system with angular scanning capability has been realized. The system uses a diode pumped Nd:YAG laser source, specifically designed for this device, and a receiving systems able to detect elastic signals at 355, 532 and 1064 nm and Raman signals at 386, 407 and 607 nm. It also allows to perform aerosol depolarization measurements at both 355nm and 532nm. A first measurement campaign has been carried out in Dunhuang, North-West of China, in the region of the Gobi desert with the aims to study and characterize desert dust at source. Optical properties of aerosol layers developing in the atmosphere have been analyzed and lidar data are discussed in terms of profiles of aerosol backscatter coefficient at 355nm, 532nm, aerosol extinction coefficient at 355nm, aerosol depolarization ratio at 355nm and 532nm and water vapor mixing ratio. Depolarization ratio measured simultaneously at two wavelengths allowed also to study its dependence on the wavelength.

  20. 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.

  1. 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

  2. LASE Measurements of Water Vapor, Aerosol, and Cloud Distributions in Saharan Air Layers and Tropical Disturbances

    NASA Technical Reports Server (NTRS)

    Ismail, Syed; Ferrare, Richard A.; Browell, Edward V.; Kooi, Susan A.; Dunion, Jason P.; Heymsfield, Gerry; Notari, Anthony; Butler, Carolyn F.; Burton, Sharon; Fenn, Marta; Krishnamurti, T. N.; Chen, Gao; Anderson, Bruce

    2010-01-01

    LASE (Lidar Atmospheric Sensing Experiment) on-board the NASA DC-8 measured high resolution profiles of water vapor and aerosols, and cloud distributions in 14 flights over the eastern North Atlantic during the NAMMA (NASA African Monsoon Multidisciplinary Analyses) field experiment. These measurements were used to study African easterly waves (AEWs), tropical cyclones (TCs), and the Saharan Air Layer(s) (SAL). Interactions between the SAL and tropical air were observed during the early stages of the TC development. These LASE measurements represent the first simultaneous water vapor and aerosol lidar measurements to study the SAL and its impact on AEWs and TCs. Examples of profile measurements of aerosol scattering ratios, aerosol extinction coefficients, aerosol optical thickness, water vapor mixing ratios, RH, and temperature are presented to illustrate their characteristics in SAL, convection, and clear air regions. LASE data suggest that the SAL suppresses low-altitude convection at the convection-SAL interface region. Mid-level convection associated with the AEW and transport are likely responsible for high water vapor content observed in the southern regions of the SAL on August 20, 2008. This interaction is responsible for the transfer of about 7 x 10(exp 15) J latent heat energy within a day to the SAL. Measurements of lidar extinction-to-backscatter ratios in the range 36+/-5 to 45+/-5 are within the range of measurements from other lidar measurements of dust. LASE aerosol extinction and water vapor profiles are validated by comparison with onboard in situ aerosol measurements and GPS dropsonde water vapor soundings, respectively.

  3. Clouds, Aerosols, and Precipitation in the Marine Boundary Layer: An Arm Mobile Facility Deployment

    SciTech Connect

    Wood, Robert; Wyant, Matthew; Bretherton, Christopher S.; Rémillard, Jasmine; Kollias, Pavlos; Fletcher, Jennifer; Stemmler, Jayson; de Szoeke, Simone; Yuter, Sandra; Miller, Matthew; Mechem, David; Tselioudis, George; Chiu, J. Christine; Mann, Julian A. L.; O’Connor, Ewan J.; Hogan, Robin J.; Dong, Xiquan; Miller, Mark; Ghate, Virendra; Jefferson, Anne; Min, Qilong; Minnis, Patrick; Palikonda, Rabindra; Albrecht, Bruce; Luke, Ed; Hannay, Cecile; Lin, Yanluan

    2015-03-01

    The Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) 38 deployment at Graciosa Island in the Azores generated a 21 month (April 2009-December 2010) 39 comprehensive dataset documenting clouds, aerosols and precipitation using the Atmospheric 40 Radiation Measurement (ARM) Mobile Facility (AMF). The scientific aim of the deployment is 41 to gain improved understanding of the interactions of clouds, aerosols and precipitation in the 42 marine boundary layer. 43 Graciosa Island straddles the boundary between the subtropics and midlatitudes in the 44 Northeast Atlantic Ocean, and consequently experiences a great diversity of meteorological and 45 cloudiness conditions. Low clouds are the dominant cloud type, with stratocumulus and cumulus 46 occurring regularly. Approximately half of all clouds contained precipitation detectable as radar 47 echoes below the cloud base. Radar and satellite observations show that clouds with tops from 1-48 11 km contribute more or less equally to surface-measured precipitation at Graciosa. A wide 49 range of aerosol conditions was sampled during the deployment consistent with the diversity of 50 sources as indicated by back trajectory analysis. Preliminary findings suggest important two-way 51 interactions between aerosols and clouds at Graciosa, with aerosols affecting light precipitation 52 and cloud radiative properties while being controlled in part by precipitation scavenging. 53 The data from at Graciosa are being compared with short-range forecasts made a variety 54 of models. A pilot analysis with two climate and two weather forecast models shows that they 55 reproduce the observed time-varying vertical structure of lower-tropospheric cloud fairly well, 56 but the cloud-nucleating aerosol concentrations less well. The Graciosa site has been chosen to 57 be a long-term ARM site that became operational in October 2013.

  4. Clouds, aerosol, and precipitation in the Marine Boundary Layer: An ARM mobile facility deployment

    SciTech Connect

    Wood, Robert; Luke, Ed; Wyant, Matthew; Bretherton, Christopher S.; Remillard, Jasmine; Kollias, Pavlos; Fletcher, Jennifer; Stemmler, Jayson; deSzoeke, S.; Yuter, Sandra; Miller, Matthew; Mechem, David; Tselioudis, George; Chiu, Christine; Mann, Julia; O Connor, Ewan; Hogan, Robin; Dong, Xiquan; Miller, Mark; Ghate, Virendra; Jefferson, Anne; Min, Qilong; Minnis, Patrick; Palinkonda, Rabindra; Albrecht, Bruce; Hannay, Cecile; Lin, Yanluan

    2014-04-27

    The Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) deployment at Graciosa Island in the Azores generated a 21-month (April 2009-December 2010) comprehensive dataset documenting clouds, aerosols, and precipitation using the Atmospheric Radiation Measurement Program (ARM) Mobile Facility (AMF). The scientific aim of the deployment is to gain improved understanding of the interactions of clouds, aerosols, and precipitation in the marine boundary layer. Graciosa Island straddles the boundary between the subtropics and midlatitudes in the Northeast Atlantic Ocean and consequently experiences a great diversity of meteorological and cloudiness conditions. Low clouds are the dominant cloud type, with stratocumulus and cumulus occurring regularly. Approximately half of all clouds contained precipitation detectable as radar echoes below the cloud base. Radar and satellite observations show that clouds with tops from 1-11 km contribute more or less equally to surface-measured precipitation at Graciosa. A wide range of aerosol conditions was sampled during the deployment consistent with the diversity of sources as indicated by back-trajectory analysis. Preliminary findings suggest important two-way interactions between aerosols and clouds at Graciosa, with aerosols affecting light precipitation and cloud radiative properties while being controlled in part by precipitation scavenging.The data from Graciosa are being compared with short-range forecasts made with a variety of models. A pilot analysis with two climate and two weather forecast models shows that they reproduce the observed time-varying vertical structure of lower-tropospheric cloud fairly well but the cloud-nucleating aerosol concentrations less well. The Graciosa site has been chosen to be a permanent fixed ARM site that became operational in October 2013.

  5. Clouds, aerosol, and precipitation in the Marine Boundary Layer: An ARM mobile facility deployment

    DOE PAGES

    Wood, Robert; Luke, Ed; Wyant, Matthew; Bretherton, Christopher S.; Remillard, Jasmine; Kollias, Pavlos; Fletcher, Jennifer; Stemmler, Jayson; deSzoeke, S.; Yuter, Sandra; et al

    2014-04-27

    The Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) deployment at Graciosa Island in the Azores generated a 21-month (April 2009-December 2010) comprehensive dataset documenting clouds, aerosols, and precipitation using the Atmospheric Radiation Measurement Program (ARM) Mobile Facility (AMF). The scientific aim of the deployment is to gain improved understanding of the interactions of clouds, aerosols, and precipitation in the marine boundary layer. Graciosa Island straddles the boundary between the subtropics and midlatitudes in the Northeast Atlantic Ocean and consequently experiences a great diversity of meteorological and cloudiness conditions. Low clouds are the dominant cloud type, with stratocumulusmore » and cumulus occurring regularly. Approximately half of all clouds contained precipitation detectable as radar echoes below the cloud base. Radar and satellite observations show that clouds with tops from 1-11 km contribute more or less equally to surface-measured precipitation at Graciosa. A wide range of aerosol conditions was sampled during the deployment consistent with the diversity of sources as indicated by back-trajectory analysis. Preliminary findings suggest important two-way interactions between aerosols and clouds at Graciosa, with aerosols affecting light precipitation and cloud radiative properties while being controlled in part by precipitation scavenging.The data from Graciosa are being compared with short-range forecasts made with a variety of models. A pilot analysis with two climate and two weather forecast models shows that they reproduce the observed time-varying vertical structure of lower-tropospheric cloud fairly well but the cloud-nucleating aerosol concentrations less well. The Graciosa site has been chosen to be a permanent fixed ARM site that became operational in October 2013.« less

  6. Mixed-layer ocean responses to anthropogenic aerosol dimming from 1870 to 2000

    NASA Astrophysics Data System (ADS)

    Dallafior, T. N.; Folini, D.; Knutti, R.; Wild, M.

    2016-01-01

    It is debated to what extent surface solar radiation (SSR) changes through varying anthropogenic aerosol emissions since industrialization affected surface temperatures (tsurf). We use mixed-layer ocean experiments with the general circulation model ECHAM6.1 and explicit aerosols (HAM2.2) to identify regions where this effect is discernible. For each decade from 1870 to 2000 we derive three equilibria: anthropogenic aerosol emissions and greenhouse gas concentrations at the respective decade's levels (ALL), either aerosols or greenhouse gases fixed at year 1850 levels (GHG and AERO). We duplicated parts of the experiments with different prescribed divergence of ocean heat transport (Q_ALL, Q_AERO, and Q_GHG). Comparing year 2000 with year 1870 equilibria, we find global average cooling of -1.4 K for AERO and warming of 1.4 K for GHG. ALL and Q_ALL warm by 0.6 K and 0.4 K, respectively. The way divergence of ocean heat transport is prescribed thus matters. Pattern correlations of year 2000 tsurf responses in ALL with the sum of AERO and GHG are higher (0.88) than with Q_ALL (0.71) confirming additivity of global patterns, but not of global means. The imprint of anthropogenic aerosols on tsurf response patterns in ALL is distinct, thus potentially detectable. Over the decades, ocean fractions affected by either changing aerosol optical depth or all-sky SSR vary in concert, supporting linkage between anthropogenic aerosols and all-sky SSR. SSR changes and tsurf responses are marginally collocated. Oceanic regions with strongest tsurf response to aerosol-induced SSR changes are the northern midlatitudes and North Pacific with tsurf sensitivities up to -0.7 K W m-2 SSR change.

  7. Mixed-layer ocean responses to anthropogenic aerosol dimming from 1870 to 2000

    NASA Astrophysics Data System (ADS)

    Dallafior, Tanja; Folini, Doris; Knutti, Reto; Wild, Martin

    2016-04-01

    It is still debated, to what extent anthropogenic aerosol-induced changes in surface solar radiation (SSR) since industrialization affected surface temperatures (tsurf). We use mixed-layer ocean (MLO) experiments with the general circulation model ECHAM6.1 and explicit aerosols (HAM2.2) to identify regions where this effect is discernible. For each decade from 1870 to 2000 we derive three equilibria: anthropogenic aerosol emissions and greenhouse gas concentrations at the respective decade's levels (ALL), either aerosols or greenhouse gases fixed at year 1850 levels (GHG and AERO). We duplicated parts of the experiments with different prescribed divergence of ocean heat transport (Q_ALL, Q_AERO, Q_GHG). Comparing year 2000 with year 1870 equilibria, we find global average cooling of -1.4K for AERO, and warming of 1.4K for GHG. ALL and Q_ALL warm by 0.6K and 0.4K, respectively. The way divergence of ocean heat transport is prescribed thus matters. Pattern correlations of year 2000 tsurf responses in ALL with the sum of AERO and GHG are higher (0.88) than with Q_ALL (0.71) confirming additivity of global patterns, but not of global means. The imprint of anthropogenic aerosols on tsurf response patterns in ALL is distinct, thus potentially detectable. Over the decades, ocean fractions affected by either changing aerosol optical depth or all-sky SSR vary in concert, supporting linkage between anthropogenic aerosols and all-sky SSR. SSR changes and tsurf responses are marginally collocated. Oceanic regions with strongest tsurf response to aerosol-induced SSR changes are the northern mid-latitudes and North Pacific with tsurf sensitivities up to -0.7K per Wm-2 SSR change. Results presented have been published under the same title in the Journal of Geophysical Research, Volume 121, DOI 10.1002/2015JD024070.

  8. 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.

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

    NASA Astrophysics Data System (ADS)

    Kaloshin, Gennady A.; Matvienko, Gennady G.

    2007-06-01

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

  10. 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

  11. A sensitivity study of atmospheric reflectance to aerosol layer height based on multi-angular polarimetric measurements

    NASA Astrophysics Data System (ADS)

    Qie, Lili; Li, Donghui; Li, Zhengqiang; Zhang, Ying; Hou, Weizhen; Chen, Xingfeng

    2015-10-01

    The reflected Solar radiance at top of atmosphere (TOA) are, to some degree, sensitive to the vertical distribution of absorbing aerosols, especially at short wavelengths (i.e. blue and UV bands). If properly exploited, it may enable the extraction of basic information on aerosol vertical distribution. In recent years, rapid development of the advanced spectral multi-angle polarimetric satellite observation technology and aerosol inversion algorithm makes the extraction of more aerosol information possible. In this study, we perform a sensitivity analysis of the reflection function at TOA to the aerosol layer height, to explore the potential for aerosol height retrievals by using multi-angle total and polarized reflectance passive observations at short wavelength. Employing a vector doubling-adding method radiative transfer code RT3, a series of numerical experiments were conducted considering different aerosol model, optical depth (AOD), single-scattering albedo (SSA), and scale height (H), also the wavelength, solar-viewing geometry, etc. The sensitivity of both intensity and polarization signals to the aerosol layer height as well as the interacted impactions with SSA and AOD are analyzed. It's found that the sensitivity of the atmospheric reflection function to aerosol scale height increase with aerosol loading (i.e. AOD) and aerosol absorption (i.e. SSA), and decrease with wavelength. The scalar reflectance is sensitive to aerosol absorption while the polarized reflectance is more influenced by the altitude. Then the aerosol H and SSA may be derived simultaneously assuming that the total and polarized radiances in UV bands deconvolve the relative influences of height and absorption. Aerosol layer height, Atmospheric reflection function, Sensitivity, Ultraviolet (UV) band.

  12. 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.

  13. On impacts of overlying solar-absorbing aerosol layers on the transition of stratocumulus to trade cumulus clouds

    NASA Astrophysics Data System (ADS)

    Fridlind, A. M.; Ackerman, A. S.; Zhou, X.; Wood, R.; Kollias, P.

    2015-12-01

    Early cloud-scale modeling work on effects of solar-absorbing aerosol layers focused on the desiccation of shallow cumulus clouds embedded with such layers, resulting from the reduction in relative humidity induced by solar heating, as well as reduced vertical mixing from stabilization of the boundary layer. Such a cloud response serves as a positive radiative forcing at the top of atmosphere, tending to warm the climate system. Subsequent work has largely targeted the impact of overlying solar-absorbing aerosol layers on stratiform clouds in the marine boundary layer, in which the solar heating increases the strength of the temperature inversion capping the boundary layer, which reduces entrainment of overlying air into the boundary layer. Because entrainment typically (but not always) reduces the average relative humidity of the boundary layer and thereby leads to a thinner cloud layer, a reduction in entrainment induced by an absorbing aerosol layer leads to a thicker cloud layer and a negative radiative forcing at the top of atmosphere, tending to cool the climate system. Here we use large-eddy simulations to assess the effects of overlying solar-absorbing aerosol layers on the transition of stratocumulus to trade cumulus clouds. Beyond the impact on the inversion strength, we also consider the changes induced by microphysical response to entrained aerosol that serve as cloud condensation nuclei, as well as reduction in solar heating of the cloud induced by the overlying aerosol layer. Observationally-based transition cases used in a recent large-eddy simulation intercomparison will be used as a starting point for the model setup, along with idealized aerosol layer properties based on remote sensing and in situ observations. We will also use the same simulation setups to evaluate and compare the response of the single column model version of the GISS climate model (with two-moment microphysics).

  14. Isotopic constraints on the role of hypohalous acids in sulfate aerosol formation in the remote marine boundary layer

    NASA Astrophysics Data System (ADS)

    Chen, Qianjie; Geng, Lei; Schmidt, Johan A.; Xie, Zhouqing; Kang, Hui; Dachs, Jordi; Cole-Dai, Jihong; Schauer, Andrew J.; Camp, Madeline G.; Alexander, Becky

    2016-09-01

    Sulfate is an important component of global atmospheric aerosol, and has partially compensated for greenhouse gas-induced warming during the industrial period. The magnitude of direct and indirect radiative forcing of aerosols since preindustrial times is a large uncertainty in climate models, which has been attributed largely to uncertainties in the preindustrial environment. Here, we report observations of the oxygen isotopic composition (Δ17O) of sulfate aerosol collected in the remote marine boundary layer (MBL) in spring and summer in order to evaluate sulfate production mechanisms in pristine-like environments. Model-aided analysis of the observations suggests that 33-50 % of sulfate in the MBL is formed via oxidation by hypohalous acids (HOX = HOBr + HOCl), a production mechanism typically excluded in large-scale models due to uncertainties in the reaction rates, which are due mainly to uncertainties in reactive halogen concentrations. Based on the estimated fraction of sulfate formed via HOX oxidation, we further estimate that daily-averaged HOX mixing ratios on the order of 0.01-0.1 parts per trillion (ppt = pmol/mol) in the remote MBL during spring and summer are sufficient to explain the observations.

  15. Planetary Boundary Layer and aerosol interactions over the Indian sub-continent

    NASA Astrophysics Data System (ADS)

    Patil, M. N.; Patil, S. D.; Waghmare, R. T.; Dharmaraj, T.

    2014-05-01

    Aerosols, both natural as well as anthropogenic, affect the radiative forcing of Earth's climate and reduce surface albedo. The Planetary Boundary Layer (PBL) height, which depends upon surface heat budget, is analyzed considering the increase in green house gases (GHGs) from pre-industrial to post-industrial era. The PBL climatology shows deeper PBL during pre-monsoon and summer monsoon seasons as compared to post-monsoon and winter. The PBL height has decreased in post-industrial decade compared to pre-industrial decade. The PBL height reduction is due to increasing aerosol and GHGs' concentrations in the recent decades, which causes surface warming and upper tropospheric cooling. Similarly, due to higher loading of the volcanic aerosol injected from the low latitude eruptions, the atmospheric circulation has been affected.

  16. Airborne Sunphotometry of African Dust and Marine Boundary Layer Aerosols in PRIDE

    NASA Technical Reports Server (NTRS)

    Livingston, John M.; Redemann, Jens; Russell, Philip; Schmid, Beat; Reid, Jeff; Pilewskie, Peter; Hipskind, R. Stephen (Technical Monitor)

    2000-01-01

    The Puerto Rico Dust Experiment (PRIDE) was conducted during summer 2000 to study the radiative, microphysical and transport properties of Saharan dust in the Caribbean region. During PRIDE, NASA Ames Research Center's six-channel airborne autotracking sunphotometer (AATS-6) was operated aboard a Piper Navajo airplane based at Roosevelt Roads Naval Station on the northeast coast of Puerto Rico. AATS-6 measurements were taken during 21 science flights off the coast of Puerto Rico in the western Caribbean. Data were acquired within and above the Marine Boundary Layer (MBL) and the Saharan Aerosol Layer (SAL) up to 5.5 km altitude tinder a wide range of dust loadings. Aerosol optical depth (AOD) spectra and columnar water vapor (CWV) values have been calculated from the AATS-6 measurements by using sunphotometer calibration data obtained at Mauna Loa Observatory (3A kin ASL) before (May) and after (October) PRIDE. Mid-visible AOD values measured near the surface during PRIDE ranged from 0.07 on the cleanest day to 0.55 on the most turbid day. Values measured above the MBL were as high as 0.35; values above the SAL were as low as 0.01. The fraction of total column AOD due to Saharan dust cannot be determined precisely from AATS-6 AOD data alone due to the uncertainty in the extent of vertical mixing of the dust down through the MBL. However, analyses of ground-based and airborne in-situ aerosol sampling measurements and ground-based aerosol lidar backscatter data should yield accurate characterization of the vertical mixing that will enable calculation of the Saharan dust AOD component from the sunphotometer data. Examples will be presented showing measured AATS-6 AOD spectra, calculated aerosol extinction and water vapor density vertical profiles, and aerosol size distributions retrieved by inversion of the AOD spectra. Near sea-surface AOD spectra acquired by AATS-6 during horizontal flight legs at 30 m ASL are available for validation of AOD derived from coincident

  17. What Causes Aerosol Growth and Ozone Production in Smoke Plumes?

    NASA Astrophysics Data System (ADS)

    Alvarado, M. J.; Prinn, R. G.

    2006-12-01

    The growth of aerosol particles and production of ozone in smoke plumes is the result of a complex interaction between horizontal diffusion, gas-phase oxidation, coagulation, and mass transfer between phases. Models allow us to separate the effects of these processes and predict their impact on the global environment. We present the results of a new model of gas and aerosol chemistry applied to young biomass burning plumes. The model includes heterogeneous chemistry, kinetic mass transfer, coagulation and the formation of secondary organic and inorganic aerosol. Comparison with measurements from SAFARI 2000 (Hobbs et al., 2003, JGR, doi:10.1029/2002JD002352) suggests the baseline model underpredicts ozone formation and the growth of aerosol within the plume. We explore whether the model predictions can be improved by (1) including heterogeneous HONO production, and (2) adding in surrogates for the uncharacterized organic compounds emitted by the biomass burning. Including the heterogeneous reaction NO2 => HONO greatly improves the match for ozone, OH, and aerosol nitrate concentration, but only when the uptake coefficient approaches 10-3, which is over an order of magnitude higher than previously reported values (Stemmler et al., 2006, doi:10.1038/nature04603). Using the reaction NO2 => 0.5 HONO + 0.5 HNO3 with an uptake coefficient of 10-3 (the top of the range recommended by Jacob, 2000, Atm. Env.,34, 2131-2159) provides an even better match for aerosol nitrate, but produces less O3 and OH than the first reaction. Direct measurements of HONO and OH in young biomass plumes would help determine if this chemistry is taking place. We used two surrogates to model the uncharacterized compounds: long chain alkanes and monoterpenes, representing primary and secondary sources of condensable compounds respectively. Complete condensation of the long-chain alkanes can account for nearly all of the observed increase in organic carbon. However, the accommodation coefficient

  18. 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%.

  19. Lidar Investigation of Tropical Nocturnal Boundary Layer Aerosols and Cloud Macrophysics

    SciTech Connect

    Manoj, M. G.; Devara, PC S.; Taraphdar, Sourav

    2013-10-01

    Observational evidence of two-way association between nocturnal boundary layer aerosols and cloud macrophysical properties under different meteorological conditions is reported in this paper. The study has been conducted during 2008-09 employing a high space-time resolution polarimetric micro-pulse lidar over a tropical urban station in India. Firstly, the study highlights the crucial role of boundary layer aerosols and background meteorology on the formation and structure of low-level stratiform clouds in the backdrop of different atmospheric stability conditions. Turbulent mixing induced by the wind shear at the station, which is associated with a complex terrain, is found to play a pivotal role in the formation and structural evolution of nocturnal boundary layer clouds. Secondly, it is shown that the trapping of energy in the form of outgoing terrestrial radiation by the overlying low-level clouds can enhance the aerosol mixing height associated with the nocturnal boundary layer. To substantiate this, the long-wave heating associated with cloud capping has been quantitatively estimated in an indirect way by employing an Advanced Research Weather Research and Forecasting (WRF-ARW) model version 2.2 developed by National Center for Atmospheric Research (NCAR), Colorado, USA, and supplementary data sets; and differentiated against other heating mechanisms. The present investigation as well establishes the potential of lidar remote-sensing technique in exploring some of the intriguing aspects of the cloud-environment relationship.

  20. Nature, Origin, Potential Composition, and Climate Impact of the Asian Tropopause Aerosol Layer (ATAL)

    NASA Technical Reports Server (NTRS)

    Fairlie, T. D.; Vernier, J.-P.; Thomason, L. W.; Natarajan, M.; Bedka, K.; Wienhold, F.; Bian J.; Martinsson, B.

    2015-01-01

    Satellite observations from SAGE II and CALIPSO indicate that summertime aerosol extinction has more than doubled in the Asian Tropopause Aerosol Layer (ATAL) since the late 1990s. Here we show remote and in-situ observations, together with results from a chemical transport model (CTM), to explore the likely composition, origin, and radiative forcing of the ATAL. We show in-situ balloon measurements of aerosol backscatter, which support the high levels observed by CALIPSO since 2006. We also show in situ measurements from aircraft, which indicate a predominant carbonaceous contribution to the ATAL (Carbon/Sulfur ratios of 2- 10), which is supported by the CTM results. We show that the peak in ATAL aerosol lags by 1 month the peak in CO from MLS, associated with deep convection over Asia during the summer monsoon. This suggests that secondary formation and growth of aerosols in the upper troposphere on monthly timescales make a significant contribution to ATAL. Back trajectory calculations initialized from CALIPSO observations provide evidence that deep convection over India is a significant source for ATAL through the vertical transport of pollution to the upper troposphere.

  1. The Collection 6 MODIS aerosol products over land and ocean

    NASA Astrophysics Data System (ADS)

    Levy, R. C.; Mattoo, S.; Munchak, L. A.; Remer, L. A.; Sayer, A. M.; Hsu, N. C.

    2013-01-01

    The twin Moderate Imaging resolution Spectroradiometer (MODIS) sensors have been flying on Terra since 2000 and Aqua since 2002, creating an incredible dataset of global Earth observations. Here, we introduce the Collection 6 (C6) algorithm to retrieve aerosol optical depth (AOD) and aerosol size parameters from MODIS-observed spectral reflectance. While not a major overhaul from the previous Collection 5 (C5) version, there are enough changes that there is significant impact on the products and their interpretation. The C6 algorithm is comprised of three sub-algorithms for retrieving aerosol properties (1) over ocean (dark in visible and near-IR wavelengths), (2) over vegetated/dark-soiled land (dark in the visible) and (3) over desert/arid land (bright in the visible). Here, we focus on the changes to both "dark target" algorithms (#1 and #2; DT-ocean and DT-land). Affecting both DT algorithms, we have updated assumptions for central wavelengths, Rayleigh optical depths and gas (H2O, O3, CO2, etc.) absorption corrections, and relaxed the solar zenith angle limit (up to ≤ 84°) to increase pole-ward coverage. For DT-land, we have updated the cloud mask to allow heavy smoke retrievals, fine-tuned the assignments for aerosol type as function of season/location, corrected bugs in the Quality Assurance (QA) logic, and added diagnostic parameters such topographic altitude. For DT-ocean, improvements include a revised cloud mask for thin-cirrus detection, inclusion of wind speed dependence in the retrieval, updates to logic of QA Confidence flag (QAC) assignment, and additions of important diagnostic information. All together, the changes to the DT algorithms result in reduced global AOD (by 0.02) over ocean and increased AOD (by 0.01) over land, along with some changes in spatial coverage. Preliminary validation shows that compared to surface-based sunphotometer data, the C6 DT-products should compare at least as well as those from C5. However, at the same time as we

  2. The Collection 6 'dark-target' MODIS Aerosol Products

    NASA Technical Reports Server (NTRS)

    Levy, Robert C.; Mattoo, Shana; Munchak, Leigh A.; Kleidman, Richard G.; Patadia, Falguni; Gupta, Pawan; Remer, Lorraine

    2013-01-01

    Aerosol retrieval algorithms are applied to Moderate resolution Imaging Spectroradiometer (MODIS) sensors on both Terra and Aqua, creating two streams of decade-plus aerosol information. Products of aerosol optical depth (AOD) and aerosol size are used for many applications, but the primary concern is that these global products are comprehensive and consistent enough for use in climate studies. One of our major customers is the international modeling comparison study known as AEROCOM, which relies on the MODIS data as a benchmark. In order to keep up with the needs of AEROCOM and other MODIS data users, while utilizing new science and tools, we have improved the algorithms and products. The code, and the associated products, will be known as Collection 6 (C6). While not a major overhaul from the previous Collection 5 (C5) version, there are enough changes that there are significant impacts to the products and their interpretation. In its entirety, the C6 algorithm is comprised of three sub-algorithms for retrieving aerosol properties over different surfaces: These include the dark-target DT algorithms to retrieve over (1) ocean and (2) vegetated-dark-soiled land, plus the (3) Deep Blue (DB) algorithm, originally developed to retrieve over desert-arid land. Focusing on the two DT algorithms, we have updated assumptions for central wavelengths, Rayleigh optical depths and gas (H2O, O3, CO2, etc.) absorption corrections, while relaxing the solar zenith angle limit (up to 84) to increase pole-ward coverage. For DT-land, we have updated the cloud mask to allow heavy smoke retrievals, fine-tuned the assignments for aerosol type as function of season location, corrected bugs in the Quality Assurance (QA) logic, and added diagnostic parameters such as topographic altitude. For DT-ocean, improvements include a revised cloud mask for thin-cirrus detection, inclusion of wind speed dependence in the retrieval, updates to logic of QA Confidence flag (QAC) assignment, and

  3. Modeling the feedback between aerosol and boundary layer processes: a case study in Beijing, China.

    PubMed

    Miao, Yucong; Liu, Shuhua; Zheng, Yijia; Wang, Shu

    2016-02-01

    Rapid development has led to frequent haze in Beijing. With mountains and sea surrounding Beijing, the pollution is found to be influenced by the mountain-plain breeze and sea-land breeze in complex ways. Meanwhile, the presence of aerosols may affect the surface energy balance and impact these boundary layer (BL) processes. The effects of BL processes on aerosol pollution and the feedback between aerosol and BL processes are not yet clearly understood. Thus, the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) is used to investigate the possible effects and feedbacks during a haze episode on 23 September 2011. Influenced by the onshore prevailing wind, sea-breeze, and upslope breeze, about 45% of surface particulate matter (PM)2.5 in Beijing are found to be contributed by its neighbor cities through regional transport. In the afternoon, the development of upslope breeze suppresses the growth of BL in Beijing by imposing a relatively low thermal stable layer above the BL, which exacerbates the pollution. Two kinds of feedback during the daytime are revealed as follows: (1) as the aerosols absorb and scatter the solar radiation, the surface net radiation and sensible heat flux are decreased, while BL temperature is increased, resulting in a more stable and shallower BL, which leads to a higher surface PM2.5 concentration in the morning and (2) in the afternoon, as the presence of aerosols increases the BL temperature over plains, the upslope breeze is weakened, and the boundary layer height (BLH) over Beijing is heightened, resulting in the decrease of the surface PM2.5 concentration there. PMID:26490909

  4. Modeling the feedback between aerosol and boundary layer processes: a case study in Beijing, China.

    PubMed

    Miao, Yucong; Liu, Shuhua; Zheng, Yijia; Wang, Shu

    2016-02-01

    Rapid development has led to frequent haze in Beijing. With mountains and sea surrounding Beijing, the pollution is found to be influenced by the mountain-plain breeze and sea-land breeze in complex ways. Meanwhile, the presence of aerosols may affect the surface energy balance and impact these boundary layer (BL) processes. The effects of BL processes on aerosol pollution and the feedback between aerosol and BL processes are not yet clearly understood. Thus, the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) is used to investigate the possible effects and feedbacks during a haze episode on 23 September 2011. Influenced by the onshore prevailing wind, sea-breeze, and upslope breeze, about 45% of surface particulate matter (PM)2.5 in Beijing are found to be contributed by its neighbor cities through regional transport. In the afternoon, the development of upslope breeze suppresses the growth of BL in Beijing by imposing a relatively low thermal stable layer above the BL, which exacerbates the pollution. Two kinds of feedback during the daytime are revealed as follows: (1) as the aerosols absorb and scatter the solar radiation, the surface net radiation and sensible heat flux are decreased, while BL temperature is increased, resulting in a more stable and shallower BL, which leads to a higher surface PM2.5 concentration in the morning and (2) in the afternoon, as the presence of aerosols increases the BL temperature over plains, the upslope breeze is weakened, and the boundary layer height (BLH) over Beijing is heightened, resulting in the decrease of the surface PM2.5 concentration there.

  5. An investigation of a potential low bias in the MODIS aerosol products over Asia

    NASA Astrophysics Data System (ADS)

    McHardy, T. M.; Shi, Y.; Zhang, J.; Reid, J. S.; Campbell, J. R.; Hsu, N. Y. C.

    2015-12-01

    Heavy aerosol plumes can be misidentified as clouds in passive satellite-based aerosol retrievals due to their relatively high visible reflectivity. Thus, over regions such as China, where a higher frequency of heavy aerosol plumes is expected, regional aerosol optical depth analyses reported from passive satellite-based aerosol products may biased low. This fundamental error can be suppressed under certain conditions. In this study, with a synergistic use of satellite observations from MODIS, OMI and CALIOP, a low bias in the MODIS Dark Target (DT) and Deep Blue (DB) aerosol products is studied over Asia for the influence of dense aerosol plume undersampling. A new scheme has been developed for detecting heavy aerosol plumes by coupling OMI aerosol index retrievals with available CALIOP level 1B and cloud and aerosol profile data. Collocated CALIOP, MODIS and OMI data are then used to further investigate the potential low bias in the MODIS DT and DB aerosol products, in an attempt to quantify the measure of undersampling in the regional DT and DB archive. Our preliminary results show that DT and DB aerosol algorithms detect about half heavy aerosol loading when CALIPSO and OMI AI believe there are heavy absorbing aerosols.

  6. The Collection 6 MODIS aerosol products over land and ocean

    NASA Astrophysics Data System (ADS)

    Levy, R. C.; Mattoo, S.; Munchak, L. A.; Remer, L. A.; Sayer, A. M.; Patadia, F.; Hsu, N. C.

    2013-11-01

    The twin Moderate resolution Imaging Spectroradiometer (MODIS) sensors have been flying on Terra since 2000 and Aqua since 2002, creating an extensive data set of global Earth observations. Here, we introduce the Collection 6 (C6) algorithm to retrieve aerosol optical depth (AOD) and aerosol size parameters from MODIS-observed spectral reflectance. While not a major overhaul from the previous Collection 5 (C5) version, there are enough changes that there are significant impacts to the products and their interpretation. The C6 aerosol data set will be created from three separate retrieval algorithms that operate over different surface types. These are the two "Dark Target" (DT) algorithms for retrieving (1) over ocean (dark in visible and longer wavelengths) and (2) over vegetated/dark-soiled land (dark in the visible), plus the "Deep Blue" (DB) algorithm developed originally for retrieving (3) over desert/arid land (bright in the visible). Here, we focus on DT-ocean and DT-land (#1 and #2). We have updated assumptions for central wavelengths, Rayleigh optical depths and gas (H2O, O3, CO2, etc.) absorption corrections, while relaxing the solar zenith angle limit (up to ≤ 84°) to increase poleward coverage. For DT-land, we have updated the cloud mask to allow heavy smoke retrievals, fine-tuned the assignments for aerosol type as function of season/location, corrected bugs in the Quality Assurance (QA) logic, and added diagnostic parameters such topographic altitude. For DT-ocean, improvements include a revised cloud mask for thin-cirrus detection, inclusion of wind speed dependence on the surface reflectance, updates to logic of QA Confidence flag (QAC) assignment, and additions of important diagnostic information. At the same time, we quantified how "upstream" changes to instrument calibration, land/sea masking and cloud masking will also impact the statistics of global AOD, and affect Terra and Aqua differently. For Aqua, all changes will result in reduced

  7. Investigation of wintertime cold-air pools and aerosol layers in the Salt Lake Valley using a lidar ceilometer

    NASA Astrophysics Data System (ADS)

    Young, Joseph Swyler

    This thesis investigates the utility of lidar ceilometers, a type of aerosol lidar, in improving the understanding of meteorology and air quality in persistent wintertime stable boundary layers, or cold-air pools, that form in urbanized valley and basin topography. This thesis reviews the scientific literature to survey the present knowledge of persistent cold-air pools, the operating principles of lidar ceilometers, and their demonstrated utility in meteorological investigations. Lidar ceilometer data from the Persistent Cold-Air Pool Study (PCAPS) are then used with meteorological and air quality data from other in situ and remote sensing equipment to investigate cold-air pools that formed in Utah's Salt Lake Valley during the winter of 2010-2011. The lidar ceilometer is shown to accurately measure aerosol layer depth and aerosol loading, when compared to visual observations. A linear relationship is found between low-level lidar backscatter and surface particulate measurements. Convective boundary layer lidar analysis techniques applied to cold-air pool ceilometer profiles can detect useful layer characteristics. Fine-scale waves are observed and analyzed within the aerosol layer, with emphasis on Kelvin-Helmholz waves. Ceilometer aerosol backscatter profiles are analyzed to quantify and describe mixing processes in persistent cold-air pools. Overlays of other remote and in-situ observations are combined with ceilometer particle backscatter to describe specific events during PCAPS. This analysis describes the relationship between the aerosol layer and the valley inversion as well as interactions with large-scale meteorology. The ceilometer observations of hydrometers are used to quantify cloudiness and precipitation during the project, observing that 50% of hours when a PCAP was present had clouds or precipitation below 5 km above ground level (AGL). Then, combining an objective technique for determining hourly aerosol layer depths and correcting this

  8. To examine the association between oscillations of the stratospheric aerosol layer peaks and different types of clouds

    NASA Astrophysics Data System (ADS)

    Mane, P. B.

    2014-11-01

    Aerosol measurements have been carried out at Kolhapur (16°42'N, 74°14'E) by using newly designed Semiautomatic Twilight Photometer. The system is a ground based simple and inexpensive but very sensitive passive remote sensing technique. The altitudes of the Junge layer peaks on measurement days were derived from the aerosol vertical profiles. One attempt is made to examine the association between oscillations of the stratospheric aerosol layer peaks and different types of clouds. The values of AND for the Junge layer peaks for each observational day were also calculated. The graph between AND at peak point of Junge layer and day numbers was also studied in comparison with High, Medium and Low level clouds. There is an annual variation in the altitude of the peak of Junge layer also. Its maximum is observed during January. The annual variation of the altitude of the peak of Junge layer and the AND of Junge layer peak showed opposite phase relation.

  9. Regional and monthly and clear-sky aerosol direct radiative effect (and forcing) derived from the GlobAEROSOL-AATSR satellite aerosol product

    NASA Astrophysics Data System (ADS)

    Thomas, G. E.; Chalmers, N.; Harris, B.; Grainger, R. G.; Highwood, E. J.

    2013-01-01

    Using the GlobAEROSOL-AATSR dataset, estimates of the instantaneous, clear-sky, direct aerosol radiative effect and radiative forcing have been produced for the year 2006. Aerosol Robotic Network sun-photometer measurements have been used to characterise the random and systematic error in the GlobAEROSOL product for 22 regions covering the globe. Representative aerosol properties for each region were derived from the results of a wide range of literature sources and, along with the de-biased GlobAEROSOL AODs, were used to drive an offline version of the Met Office unified model radiation scheme. In addition to the mean AOD, best-estimate run of the radiation scheme, a range of additional calculations were done to propagate uncertainty estimates in the AOD, optical properties, surface albedo and errors due to the temporal and spatial averaging of the AOD fields. This analysis produced monthly, regional estimates of the clear-sky aerosol radiative effect and its uncertainty, which were combined to produce annual, global mean values of (-6.7 ± 3.9) W m-2 at the top of atmosphere (TOA) and (-12 ± 6) W m-2 at the surface. These results were then used to give estimates of regional, clear-sky aerosol direct radiative forcing, using modelled pre-industrial AOD fields for the year 1750 calculated for the AEROCOM PRE experiment. However, as it was not possible to quantify the uncertainty in the pre-industrial aerosol loading, these figures can only be taken as indicative and their uncertainties as lower bounds on the likely errors. Although the uncertainty on aerosol radiative effect presented here is considerably larger than most previous estimates, the explicit inclusion of the major sources of error in the calculations suggest that they are closer to the true constraint on this figure from similar methodologies, and point to the need for more, improved estimates of both global aerosol loading and aerosol optical properties.

  10. Regional and monthly and clear-sky aerosol direct radiative effect (and forcing) derived from the GlobAEROSOL-AATSR satellite aerosol product

    NASA Astrophysics Data System (ADS)

    Thomas, G. E.; Chalmers, N.; Harris, B.; Grainger, R. G.; Highwood, E. J.

    2012-07-01

    Using the GlobAEROSOL-AATSR dataset, estimates of the instantaneous, clear-sky, direct aerosol radiative effect and radiative forcing have been produced for the year 2006. Aerosol Robotic Network sun-photometer measurements have been used to characterise the random and systematic error in the GlobAEROSOL product for 22 regions covering the globe. Representative aerosol properties for each region have been derived from the results of a wide range of literature sources and, along with the de-biased GlobAEROSOL AODs, were used to drive an offline version of the Met Office unified model radiation scheme. In addition to the mean AOD, best-estimate run of the radiation scheme, a range of additional calculations were done to propagate uncertainty estimates in the AOD, optical properties, surface albedo and errors due to the temporal and spatial averaging of the AOD fields. This analysis produced monthly, regional estimates of the clear-sky aerosol radiative effect and its uncertainty, which produce annual, global mean values of (-6.7 ± 3.9) W m-2 at the top of atmosphere (TOA) and (-12 ± 6) W m-2 at the surface. These results were then used to produce estimates of regional, clear-sky aerosol direct radiative forcing, using modelled pre-industrial AOD fields for 1750 calculated for the AEROCOM PRE experiment. However, as it was not possible to quantify the uncertainty in the pre-industrial aerosol loading, these figures can only be taken as indicative and their uncertainties as lower bounds on the likely errors. Although the uncertainty on aerosol radiative effect presented here is considerably larger than most previous estimates, the explicit inclusion of the major sources of error in the calculations suggest that they are closer to the true constraint on this figure from similar methodologies, and point to the need for more, improved estimates of both global aerosol loading and aerosol optical properties.

  11. Lidar measurements of sub-visible aerosol layers in the free troposphere at a tropical coastal station in Trivandrum, India

    NASA Astrophysics Data System (ADS)

    Veerabuthiran, Sangaipillai; Satyanarayana, Malladi; Sreeja, Rajappan; Presennakumar, Bhargavan; Muraleedharen Nair, Sivarama Pillai; Ramakrishna Rao, Duggirala; Pillai Mohankumar, Santhibhavan Vasudevan

    2006-12-01

    Lidar observations had been conducted to study the long-range transport of aerosol and their effect at tropical station, Trivandrum during the period of 2001-2003. The presence of aerosol layers was observed on many days below about 5 km during the above period. The monthly values of aerosol extinction coefficient profile showed the presence of aerosol layer in the height region up to about 5 km during the summer monsoon periods. However, during the Asian winter monsoon period the aerosol layers were observed in the altitude region between 0.6 and 3 km. The extinction values were high in the winter season and were typically found to be 3.4×10-4 m-1. The aerosol optical depth was calculated by integrating the extinction values in the aerosol layer region and it was found to be between 0.2 and 0.35. The plausible reasons for the formation of these layers were explained using the wind circulation pattern and air back trajectories.

  12. A Numerical Study of Sea-Spray Aerosol Motion in a Coastal Thermal Internal Boundary Layer

    NASA Astrophysics Data System (ADS)

    Liang, Tinghao; Yu, Xiping

    2016-08-01

    A three-dimensional large-eddy simulation model is applied to the study of sea-spray aerosol transport, dispersion and settling in the coastal thermal internal boundary layer (IBL) formed by cool airflow from the open sea to the warm land. An idealized situation with constant inflow from the ocean and constant heat flux over the coastal land is considered. The numerical results confirm that the thickness of the coastal thermal IBL increases with the distance from the coastline until the outer edge of the IBL penetrates into the capping inversion layer. The thickness increases also with time until a fully-developed thermal boundary layer is formed. In addition, the thickness of the coastal thermal IBL increases more rapidly when the heat flux over the land is greater. Existence of large-scale eddies within the thermal IBL is identified and the turbulence intensity within the thermal IBL is also found to be significantly higher than that above. It is also indicated that the vertical position of the maximum concentration does not occur at the surface but increases as sea-spray aerosols are transported inland. The vertical position of the maximum flux of sea-spray aerosols within the coastal thermal IBL is shown to coincide with that of the maximum vertical velocity fluctuations when the coastal thermal IBL is fully developed with increased distance in the airflow direction.

  13. What is the "Clim-Likely" aerosol product?

    Atmospheric Science Data Center

    2014-12-08

    ... model were medium and coarse mode mineral dust, sulfate, sea salt, black carbon, and carbonaceous aerosols. Five aerosol air mass "Mixing ... component particles in the column for climatologically common aerosol air masses. Each sub-group identifies the dominant particles ...

  14. MISR Global Aerosol Product Assessment by Comparison with AERONET

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph A.; Gaitley, Barbara J.; Garay, Michael J.; Diner, David J.; Eck, Thomas F.; Smirnov, Alexander; Holben, Brent N.

    2010-01-01

    A statistical approach is used to assess the quality of the MISR Version 22 (V22) aerosol products. Aerosol Optical Depth (AOD) retrieval results are improved relative to the early post- launch values reported by Kahn et al. [2005a], varying with particle type category. Overall, about 70% to 75% of MISR AOD retrievals fall within 0.05 or 20% AOD of the paired validation data, and about 50% to 55% are within 0.03 or 10% AOD, except at sites where dust, or mixed dust and smoke, are commonly found. Retrieved particle microphysical properties amount to categorical values, such as three groupings in size: "small," "medium," and "large." For particle size, ground-based AERONET sun photometer Angstrom Exponents are used to assess statistically the corresponding MISR values, which are interpreted in terms of retrieved size categories. Coincident Single-Scattering Albedo (SSA) and fraction AOD spherical data are too limited for statistical validation. V22 distinguishes two or three size bins, depending on aerosol type, and about two bins in SSA (absorbing vs. non-absorbing), as well as spherical vs. non-spherical particles, under good retrieval conditions. Particle type sensitivity varies considerably with conditions, and is diminished for mid-visible AOD below about 0.15 or 0.2. Based on these results, specific algorithm upgrades are proposed, and are being investigated by the MISR team for possible implementation in future versions of the product.

  15. Coordinated Airborne, Spaceborne, and Ground-Based Measurements of Massive, Thick Aerosol Layers During the Dry Season in Southern Africa

    NASA Technical Reports Server (NTRS)

    Schmid, B.; Redemann, J.; Russell, P. B.; Hobbs, P. V.; Hlavka, D. L.; McGill, M. J.; Holben, B. N.; Welton, E. J.; Campbell, J.; Torres, O.; Hipskind, R. Stephen (Technical Monitor)

    2002-01-01

    During the dry-season airborne campaign of the Southern African Regional Science Initiative (SAFARI 2000), unique coordinated observations were made of massive, thick aerosol layers. These layers were often dominated by aerosols from biomass burning. We report on airborne Sunphotometer measurements of aerosol optical depth (lambda=354-1558 nm), columnar water vapor, and vertical profiles of aerosol extinction and water vapor density that were obtained aboard the University of Washington's Convair-580 research aircraft. We compare these with ground-based AERONET Sun/sky radiometer results, with ground based lidar data MPL-Net), and with measurements from a downward-pointing lidar aboard the high-flying NASA ER-2 aircraft. Finally, we show comparisons between aerosol optical depths from the Sunphotometer and those retrieved over land and over water using four spaceborne sensors (TOMS (Total Ozone Mapping Spectrometer), MODIS (Moderate Resolution Imaging Spectrometer), MISR (Multiangle Imaging Spectroradiometer) and ATSR-2 (Along Track Scanning Radiometer)).

  16. Coordinated Airborne, Spaceborne and Ground-based Measurements of Massive Thick Aerosol Layers during the Dry Season in Southern Africa

    NASA Technical Reports Server (NTRS)

    Schmid, B.; Redemann, J.; Russell, P. B.; Hobbs, P. V.; Hlavka, D. L.; McGill, M. J.; Holben, B. N.; Welton, E. J.; Campbell, J. R.; Torres, O.

    2003-01-01

    During the dry season airborne campaign of the Southern African Regional Science Initiative (SAFARI 2000), coordinated observations were made of massive thick aerosol layers. These layers were often dominated by aerosols from biomass burning. We report on airborne Sun photometer measurements of aerosol optical depth (lambda = 0.354- 1.557 microns), columnar water vapor, and vertical profiles of aerosol extinction and water vapor density that were obtained aboard the University of Washington's Convair-580 research aircraft. We compare these with ground-based AERONET Sun/sky radiometer results, with ground based lidar data (MPL-Net), and with measurements from a downward pointing lidar aboard the high-flying NASA ER-2 aircraft. Finally, we show comparisons between aerosol optical depths fiom the Sun photometer and those retrieved over land and over water using four spaceborne sensors (TOMS, MODIS, MISR, and ATSR-2).

  17. Single-Particle Black Carbon Aerosol Verticle Profiles From the Boundary Layer to the Lower Stratosphere

    NASA Astrophysics Data System (ADS)

    Schwarz, J. P.; Gao, R. S.; Fahey, D. W.; Laurel, W. A.; Thomson, D. S.; Kok, G. L.; Baumgardner, D.; Wilson, J. C.; Lopez, J.; Aikin, K.; Jost, H.; Thompson, T. L.; Reeves, J. M.; Lowenstein, M.

    2005-12-01

    A single-particle soot photometer (SP2) was flown on a NASA WB-57F high-altitude research aircraft in November 2004 from Houston, TX. The SP2 uses laser-induced incandescence to directly measure the mass of individual black-carbon (BC) particles in the mass range of ~0.3-300 fg. Scattered light is used to size non-absorbing aerosols in the range of ~150 - 700 nm diameter. Data from two mid-latitude flights has been used to generate size distributions and profiles of both aerosol types from the boundary layer to the lower stratosphere. Results for scattering aerosol concentrations are in good agreement with typical particle spectrometer measurements in the same region. Mass mixing ratios of BC between 5 and 18.7 km were roughly an order of magnitude lower than typical values as reported with wire impactor measurements and as predicted by two global BC models. The impact of this discrepancy on estimates of direct radiative forcing of BC aerosol will also be discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  19. Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) Final Campaign Report

    SciTech Connect

    Wood, R.

    2016-01-01

    The extensive coverage of low clouds over the subtropical eastern oceans greatly impacts the current climate. In addition, the response of low clouds to changes in atmospheric greenhouse gases and aerosols is a major source of uncertainty, which thwarts accurate prediction of future climate change. Low clouds are poorly simulated in climate models, partly due to inadequate long-term simultaneous observations of their macrophysical and microphysical structure, radiative effects, and associated aerosol distribution in regions where their impact is greatest. The thickness and extent of subtropical low clouds is dependent on tight couplings between surface fluxes of heat and moisture, radiative cooling, boundary layer turbulence, and precipitation (much of which evaporates before reaching the ocean surface and is closely connected to the abundance of cloud condensation nuclei). These couplings have been documented as a result of past field programs and model studies. However, extensive research is still required to achieve a quantitative understanding sufficient for developing parameterizations, which adequately predict aerosol indirect effects and low cloud response to climate perturbations. This is especially true of the interactions between clouds, aerosol, and precipitation. These processes take place in an ever-changing synoptic environment that can confound interpretation of short time period observations.

  20. A merged aerosol dataset based on MODIS and MISR Aerosol Optical Depth products

    NASA Astrophysics Data System (ADS)

    Singh, Manoj K.; Gautam, Ritesh; Venkatachalam, Parvatham

    2016-05-01

    Aerosol Optical Depth (AOD) products available from MODIS and MISR observations are widely used for aerosol characterization, and global/environmental change studies. These products are based on different retrieval-algorithms, resolutions, sampling, and cloud-screening schemes, which have led to global/regional biases. Thus a merged product is desirable which bridges this gap by utilizing strengths from each of the sensors. In view of this, we have developed a "merged" AOD product based on MODIS and MISR AOD datasets, using Bayesian principles which takes error distributions from ground-based AOD measurements (from AERONET). Our methodology and resulting dataset are especially relevant in the scenario of combining multi-sensor retrievals for satellite-based climate data records; particularly for long-term studies involving AOD. Specifically for MISR AOD product, we also developed a methodology to produce a gap-filled dataset, using geostatistical methods (e.g. Kriging), taking advantage of available MODIS data. Merged and spatially-complete AOD datasets are inter-compared with other satellite products and with AERONET data at three stations- Kanpur, Jaipur and Gandhi College, in the Indo-Gangetic Plains. The RMSE of merged AOD (0.08-0.09) is lower than MISR (0.11-0.20) and MODIS (0.15-0.27). It is found that merged AOD has higher correlation with AERONET data (r within 0.92-0.95), compared to MISR (0.74-0.86) and MODIS (0.69-0.84) data. In terms of Expected Error, the accuracy of valid merged AOD is found to be superior as percent of merged AOD within error envelope are larger (71-92%), compared to MISR (43-61%) and MODIS (50-70%).

  1. Classification of Dust Days by Satellite Remotely Sensed Aerosol Products

    NASA Technical Reports Server (NTRS)

    Sorek-Hammer, M.; Cohen, A.; Levy, Robert C.; Ziv, B.; Broday, D. M.

    2013-01-01

    Considerable progress in satellite remote sensing (SRS) of dust particles has been seen in the last decade. From an environmental health perspective, such an event detection, after linking it to ground particulate matter (PM) concentrations, can proxy acute exposure to respirable particles of certain properties (i.e. size, composition, and toxicity). Being affected considerably by atmospheric dust, previous studies in the Eastern Mediterranean, and in Israel in particular, have focused on mechanistic and synoptic prediction, classification, and characterization of dust events. In particular, a scheme for identifying dust days (DD) in Israel based on ground PM10 (particulate matter of size smaller than 10 nm) measurements has been suggested, which has been validated by compositional analysis. This scheme requires information regarding ground PM10 levels, which is naturally limited in places with sparse ground-monitoring coverage. In such cases, SRS may be an efficient and cost-effective alternative to ground measurements. This work demonstrates a new model for identifying DD and non-DD (NDD) over Israel based on an integration of aerosol products from different satellite platforms (Moderate Resolution Imaging Spectroradiometer (MODIS) and Ozone Monitoring Instrument (OMI)). Analysis of ground-monitoring data from 2007 to 2008 in southern Israel revealed 67 DD, with more than 88 percent occurring during winter and spring. A Classification and Regression Tree (CART) model that was applied to a database containing ground monitoring (the dependent variable) and SRS aerosol product (the independent variables) records revealed an optimal set of binary variables for the identification of DD. These variables are combinations of the following primary variables: the calendar month, ground-level relative humidity (RH), the aerosol optical depth (AOD) from MODIS, and the aerosol absorbing index (AAI) from OMI. A logistic regression that uses these variables, coded as binary

  2. 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.

  3. Interaction between aerosol and the planetary boundary layer depth at sites in the US and China

    NASA Astrophysics Data System (ADS)

    Sawyer, V. R.

    2015-12-01

    The depth of the planetary boundary layer (PBL) defines a changing volume into which pollutants from the surface can disperse, which affects weather, surface air quality and radiative forcing in the lower troposphere. Model simulations have also shown that aerosol within the PBL heats the layer at the expense of the surface, changing the stability profile and therefore also the development of the PBL itself: aerosol radiative forcing within the PBL suppresses surface convection and causes shallower PBLs. However, the effect has been difficult to detect in observations. The most intensive radiosonde measurements have a temporal resolution too coarse to detect the full diurnal variability of the PBL, but remote sensing such as lidar can fill in the gaps. Using a method that combines two common PBL detection algorithms (wavelet covariance and iterative curve-fitting) PBL depth retrievals from micropulse lidar (MPL) at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site are compared to MPL-derived PBL depths from a multiyear lidar deployment at the Hefei Radiation Observatory (HeRO). With aerosol optical depth (AOD) measurements from both sites, it can be shown that a weak inverse relationship exists between AOD and daytime PBL depth. This relationship is stronger at the more polluted HeRO site than at SGP. Figure: Mean daily AOD vs. mean daily PBL depth, with the Nadaraya-Watson estimator overlaid on the kernel density estimate. Left, SGP; right, HeRO.

  4. LASE Measurements of Water Vapor, Aerosol, and Cloud Distributions in Saharan Air Layers and Tropical Disturbances

    NASA Technical Reports Server (NTRS)

    Ismail, Syed; Ferrare, Richard; Browell, Edward; Kooi, Susan; Notari, Anthony; Butler, Carolyn; Burton, Sharon; Fenn, Marta; Krishnamurti, T. N.; Dunion, Jason; Heymsfield, Gerry; Anderson, Bruce

    2008-01-01

    LASE (Lidar Atmospheric Sensing Experiment) onboard the NASA DC-8 was used to measure high resolution profiles of water vapor and aerosols, and cloud distributions in 14 flights over the eastern Atlantic region during the NAMMA (NASA African Monsoon Multidisciplinary Analyses) field experiment, which was conducted from August 15 to September 12, 2006. These measurements were made in conjunction with flights designed to study African Easterly Waves (AEW), Tropical Disturbances (TD), and Saharan Aerosol Layers (SALs) as well as flights performed in clear air and convective regions. As a consequence of their unique radiative properties and dynamics, SAL layers have a significant influence in the development of organized convection associated with TD. Interactions of the SAL with tropical air during early stages of the development of TD were observed. These LASE measurements represent the first simultaneous water vapor and aerosol lidar measurements to study the SAL and its impact on TDs and hurricanes. Seven AEWs were studied and four of these evolved into tropical storms and three did not. Three out of the four tropical storms evolved into hurricanes.

  5. MODIS aerosol product at 3 km spatial resolution for urban and air quality studies

    NASA Astrophysics Data System (ADS)

    Mattoo, S.; Remer, L. A.; Levy, R. C.; Holben, B. N.; Smirnov, A.

    2008-12-01

    The MODerate resolution Imaging Spectroradiometer (MODIS) aboard the Terra and Aqua satellites has been producing an aerosol product since early 2000. The original product reports aerosol optical depth and a variety of other aerosol parameters at a spatial resolution of 10 km over both land and ocean. The 10 km product is actually constructed from 500 m pixels, which permits a strict selection process to choose the "best" or "cleanest" pixels in each 10 km square for use in the aerosol retrieval. Thus, the original 10 km product provides a useful product, accurate in many applications. However, the 10 km product can miss narrow aerosol plumes and the spatial variability associated with urban air pollution. The MODIS aerosol team will be introducing a finer resolution aerosol product over land regions in the next release of the product (Collection 6). The new product will be produced at 3 km resolution. It is based on the same procedures as the original product and benefits from the same spatial variability criteria for finding and masking cloudy pixels. The 3 km product does capture the higher spatial variability associated with individual aerosol plumes. However, it is noisier than the 10 km product. Both products will be available operationally in Collection 6. The new 3km product offers new synergistic possibilities with PM2.5 monitoring networks, AERONET and various air quality models such as CMAQ.

  6. The detection of clouds, aerosols and marine atmospheric boundary layer characteristics from simulated GLAS data

    NASA Technical Reports Server (NTRS)

    Palm, Stephen P.; Spinhirne, James D.

    1998-01-01

    Scheduled for launch in 2001 as part of NASA's Earth Observing System (EOS), the Geoscience Laser Altimeter System (GLAS) will provide continuous laser sounding of the earth's atmosphere from space for the first time. From its polar orbit about 600 km above the surface, GLAS will employ a 40 Hz solid state laser operating at 1064 nm to measure topography to an accuracy of 10 cm. Simultaneously, the atmospheric channels (1064 and 532 nm) of GLAS will provide profiles of atmospheric backscatter from 40 km to the ground with 75 meter vertical resolution (Spinhirne and Palm, 1996). These measurements will give scientists an unprecedented global data set on the vertical structure of clouds and aerosols which will greatly aid research efforts aimed at understanding their effects on climate and their role in climate change (Hartman, 1994). To better understand and predict the performance of the GLAS atmospheric channels, a computer model was developed to simulate the type of signal that the instrument would likely produce. The model uses aircraft lidar data and provides realistic simulated GLAS data sets over large areas spanning a wide range of atmospheric conditions. These simulated GLAS datasets are invaluable for designing and testing algorithms for the retrieval of parameters such as cloud and aerosol layer height, optical depth and extinction cross section. This work is currently proceeding and in this paper we will present results of the cloud and aerosol detection algorithm with emphasis on the detection of Marine Atmospheric Boundary Layer (MABL) aerosol. In addition, we use a recently developed technique to ascertain the feasability of estimating MABL moisture and temperature structure from spaceborne systems such as GLAS.

  7. Toward a Coherent Detailed Evaluation of Aerosol Data Products from Multiple Satellite Sensors

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles; Petrenko, Maksym; Leptoukh, Gregory

    2011-01-01

    Atmospheric aerosols represent one of the greatest uncertainties in climate research. Although satellite-based aerosol retrieval has practically become routine, especially during the last decade, there is often disagreement between similar aerosol parameters retrieved from different sensors, leaving users confused as to which sensors to trust for answering important science questions about the distribution, properties, and impacts of aerosols. As long as there is no consensus and the inconsistencies are not well characterized and understood, there will be no way of developing reliable climate data records from satellite aerosol measurements. Fortunately, the most globally representative well-calibrated ground-based aerosol measurements corresponding to the satellite-retrieved products are available from the Aerosol Robotic Network (AERONET). To adequately utilize the advantages offered by this vital resource, an online Multi-sensor Aerosol Products Sampling System (MAPSS) was recently developed. The aim of MAPSS is to facilitate detailed comparative analysis of satellite aerosol measurements from different sensors (Terra-MODIS, Aqua-MODIS, TerraMISR, Aura-OMI, Parasol-POLDER, and Calipso-CALIOP) based on the collocation of these data products over AERONET stations. In this presentation, we will describe the strategy of the MASS system, its potential advantages for the aerosol community, and the preliminary results of an integrated comparative uncertainly analysis of aerosol products from multiple satellite sensors.

  8. The Multi-Sensor Aerosol Products Sampling System (MAPSS) for Integrated Analysis of Satellite Retrieval Uncertainties

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles; Petrenko, Maksym; Leptoukh, Gregory

    2010-01-01

    Among the known atmospheric constituents, aerosols represent the greatest uncertainty in climate research. Although satellite-based aerosol retrieval has practically become routine, especially during the last decade, there is often disagreement between similar aerosol parameters retrieved from different sensors, leaving users confused as to which sensors to trust for answering important science questions about the distribution, properties, and impacts of aerosols. As long as there is no consensus and the inconsistencies are not well characterized and understood ', there will be no way of developing reliable climate data records from satellite aerosol measurements. Fortunately, the most globally representative well-calibrated ground-based aerosol measurements corresponding to the satellite-retrieved products are available from the Aerosol Robotic Network (AERONET). To adequately utilize the advantages offered by this vital resource,., an online Multi-sensor Aerosol Products Sampling System (MAPSS) was recently developed. The aim of MAPSS is to facilitate detailed comparative analysis of satellite aerosol measurements from different sensors (Terra-MODIS, Aqua-MODIS, Terra-MISR, Aura-OMI, Parasol-POLDER, and Calipso-CALIOP) based on the collocation of these data products over AERONET stations. In this presentation, we will describe the strategy of the MAPSS system, its potential advantages for the aerosol community, and the preliminary results of an integrated comparative uncertainty analysis of aerosol products from multiple satellite sensors.

  9. 21 CFR 700.16 - Use of aerosol cosmetic products containing zirconium.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 7 2012-04-01 2012-04-01 false Use of aerosol cosmetic products containing... SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.16 Use of aerosol cosmetic products containing zirconium. (a) Zirconium-containing complexes have been used as an...

  10. 21 CFR 700.16 - Use of aerosol cosmetic products containing zirconium.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 7 2013-04-01 2013-04-01 false Use of aerosol cosmetic products containing... SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.16 Use of aerosol cosmetic products containing zirconium. (a) Zirconium-containing complexes have been used as an...

  11. 21 CFR 700.16 - Use of aerosol cosmetic products containing zirconium.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 7 2014-04-01 2014-04-01 false Use of aerosol cosmetic products containing... SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.16 Use of aerosol cosmetic products containing zirconium. (a) Zirconium-containing complexes have been used as an...

  12. 21 CFR 700.16 - Use of aerosol cosmetic products containing zirconium.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 7 2010-04-01 2010-04-01 false Use of aerosol cosmetic products containing... SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.16 Use of aerosol cosmetic products containing zirconium. (a) Zirconium-containing complexes have been used as an...

  13. 21 CFR 700.16 - Use of aerosol cosmetic products containing zirconium.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 7 2011-04-01 2010-04-01 true Use of aerosol cosmetic products containing... SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.16 Use of aerosol cosmetic products containing zirconium. (a) Zirconium-containing complexes have been used as an...

  14. Mixing-Height Time Series from Operational Ceilometer Aerosol-Layer Heights

    NASA Astrophysics Data System (ADS)

    Lotteraner, Christoph; Piringer, Martin

    2016-07-01

    A new method is described to derive mixing-height time series directly from aerosol-layer height data available from a Vaisala CL51 ceilometer. As complete as possible mixing-height time series are calculated by avoiding outliers, filling data gaps by linear interpolation, and smoothing. In addition, large aerosol-layer heights at night that can be interpreted as residual layers are not assigned as mixing heights. The resulting mixing-height time series, converted to an appropriate data format, can be used as input for dispersion calculations. Two case examples demonstrate in detail how the method works. The mixing heights calculated using ceilometer data are compared with values determined from radiosounding data at Vienna by applying the parcel, Heffter, and Richardson methods. The results of the parcel method, obtained from radiosonde profiles at noon, show the best fit to the ceilometer-derived mixing heights. For midnight radiosoundings, larger deviations between mixing heights from the ceilometer and those deduced from the potential temperature profiles of the soundings are found. We use data from two Vaisala CL51 ceilometers, operating in the Vienna area at an urban and rural site, respectively, during an overlapping period of about 1 year. In addition to the case studies, the calculated mixing-height time series are also statistically evaluated and compared, demonstrating that the ceilometer-based mixing height follows an expected daily and seasonal course.

  15. Mixing-Height Time Series from Operational Ceilometer Aerosol-Layer Heights

    NASA Astrophysics Data System (ADS)

    Lotteraner, Christoph; Piringer, Martin

    2016-11-01

    A new method is described to derive mixing-height time series directly from aerosol-layer height data available from a Vaisala CL51 ceilometer. As complete as possible mixing-height time series are calculated by avoiding outliers, filling data gaps by linear interpolation, and smoothing. In addition, large aerosol-layer heights at night that can be interpreted as residual layers are not assigned as mixing heights. The resulting mixing-height time series, converted to an appropriate data format, can be used as input for dispersion calculations. Two case examples demonstrate in detail how the method works. The mixing heights calculated using ceilometer data are compared with values determined from radiosounding data at Vienna by applying the parcel, Heffter, and Richardson methods. The results of the parcel method, obtained from radiosonde profiles at noon, show the best fit to the ceilometer-derived mixing heights. For midnight radiosoundings, larger deviations between mixing heights from the ceilometer and those deduced from the potential temperature profiles of the soundings are found. We use data from two Vaisala CL51 ceilometers, operating in the Vienna area at an urban and rural site, respectively, during an overlapping period of about 1 year. In addition to the case studies, the calculated mixing-height time series are also statistically evaluated and compared, demonstrating that the ceilometer-based mixing height follows an expected daily and seasonal course.

  16. Lidar Observations of Stratospheric Aerosol Layer After the Mt. Pinatubo Volcanic Eruption

    NASA Technical Reports Server (NTRS)

    Nagai, Tomohiro; Uchino, Osamu; Fujimoto, Toshifumi

    1992-01-01

    The volcano Mt. Pinatubo located on the Luzon Island, Philippines, had explosively erupted on June 15, 1991. The volcanic eruptions such as volcanic ash, SO2 and H2O reached into the stratosphere over 30 km altitude by the NOAA-11 satellite observation and this is considered one of the biggest volcanic eruptions in this century. A grandiose volcanic eruption influences the atmosphere seriously and causes many climatic effects globally. There had been many impacts on radiation, atmospheric temperature and stratospheric ozone after some past volcanic eruptions. The main cause of volcanic influence depends on stratospheric aerosol, that stay long enough to change climate and other meteorological conditions. Therefore it is very important to watch stratospheric aerosol layers carefully and continuously. Standing on this respect, we do not only continue stratospheric aerosol observation at Tsukuba but also have urgently developed another lidar observational point at Naha in Okinawa Island. This observational station could be thought valuable since there is no lidar observational station in this latitudinal zone and it is much nearer to Mt. Pinatubo. Especially, there is advantage to link up these two stations on studying the transportation mechanism in the stratosphere. In this paper, we present the results of lidar observations at Tsukuba and Naha by lidar systems with Nd:YAG laser.

  17. 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

  18. Oxygenated products of sesquiterpenes in secondary organic aerosol

    NASA Astrophysics Data System (ADS)

    van Eijck, A.; Kampf, C.; Hoffmann, T.

    2012-04-01

    Secondary organic aerosol (SOA) has a huge impact on air quality and climate change. It influences the Earth radiative budget through absorbing, scattering and reflecting radiation as well as the formation of clouds because the particulates can act as cloud condensation nuclei (CCN). Furthermore, it plays an important role for human health. SOA is formed from gaseous precursors which get oxidized by ozone, OH- and NO3-radicals in the atmosphere. Due to their low vapor pressure these degradation products can nucleate to form new particles or they can condense on existing aerosol particles. Despite the major progress in research during the last few years the actual chemical composition as well as the contribution of various volatile organic compounds (VOCs) to the formation of secondary organic aerosol is still partially unknown. Recent studies indicate that sesquiterpenes play an important role in the formation of SOA because of the low volatility of their oxygenated products (Lee et al., 2006). Their emission is estimated to be about 14,8 Tg per year (Henze et al., 2008), however, these emission rates remain highly uncertain due to the lack of quantitative emission rate measurements. In addition, the knowledge about the actual atmospheric degradation mechanism and the main oxidation products of sesquiterpenes is quite limited. β-Caryophyllene, α-humulene, α-farnesene and β-farnesene are the most abundant sequiterpenes in many sesquiterpene emission profiles. But also aromadendren, α-bergamotene and δ-cadinene and germacrene-D can contribute significantly to some emission profiles (Duhl et al., 2008). To determine the major oxygenated products of sesquiterpenes in SOA, reaction chamber experiments with different sesquiterpenes and ozone were performed in a 100 L reaction chamber. To measure the time dependent formation of initial oxidation products, an APCI-IT-MS was directly connected to the reaction chamber. After 2 hours the APCI-IT-MS was replaced by a

  19. Impacts of sources and aging on submicrometer aerosol properties in the marine boundary layer across the Gulf of Maine

    NASA Astrophysics Data System (ADS)

    Quinn, P. K.; Bates, T. S.; Coffman, D.; Onasch, T. B.; Worsnop, D.; Baynard, T.; de Gouw, J. A.; Goldan, P. D.; Kuster, W. C.; Williams, E.; Roberts, J. M.; Lerner, B.; Stohl, A.; Pettersson, A.; Lovejoy, E. R.

    2006-12-01

    Measurements were made on board the NOAA RV Ronald H. Brown during the second New England Air Quality Study (NEAQS 2004) to determine the source of the aerosol in the region and how sources and aging processes affect submicrometer aerosol chemical composition and optical properties. Using the Lagrangian particle dispersion model FLEXPART in combination with gas phase tracer compounds, local (urban), regional (NE U.S. urban corridor of Washington, D.C.; New York; and Boston), and distant (midwest industries and North American forest fires) sources were identified. Submicrometer aerosol measured near the source region (Boston Harbor) had a molar equivalence ratio near one with respect to NH4+, NO3-, and SO4=, had a large mass fraction of particulate organic matter (POM) relative to SO4=, and had relatively unoxidized POM. As distance from the source region increased, the submicrometer aerosol measured in the marine boundary layer became more acidic and had a lower POM mass fraction, and the POM became more oxidized. The relative humidity dependence of light extinction reflected the change in aerosol composition being lower for the near-source aerosol and higher for the more processed aerosol. A factor analysis performed on a combined data set of aerosol and gas phase parameters showed that the POM measured during the experiment was predominantly of secondary anthropogenic origin.

  20. Secondary aerosol formation in the planetary boundary layer: observations on board on a Zeppelin and analysis by back plume approach

    NASA Astrophysics Data System (ADS)

    Kazanas, Konstantinos; Rubach, Florian; Tillmann, Ralf; Mentel, Thomas; Elbern, Hendrik; Wahner, Andreas; Zeppelin Pegasos-Team 2012

    2014-05-01

    The airship Zeppelin NT is an airborne platform capable of flying at low speed throughout the entire planetary boundary layer (PBL), thus the Zeppelin is an ideal platform to study regional processes in the lowest layers of the atmosphere with high spatial resolution. Atmospheric aerosol as a medium long lived tracer substance is of particular interest due to its influence on the global radiation budget. Due to its lifetime of up to several days secondary aerosol at a certain location can result from local production or from transport processes. Flight patterns during the PEGASOS campaign 2012 in the Po Valley included vertical profiles and transects through regions of interest We analysed one flight with North-South transects between the Apennin and San Pietro Capofiume and one flight with vertical profiles near the supersite San Pietro Capofiume to shed light on local production and transport processes. Model analyses were performed by using 12 hour back plumes for selected points of measurements to determine the regions which contributed to the air mass under observation. This analysis was done using the EURopean Air pollution Dispersion and Inverse Modelling (EURAD-IM) system. As a novel method, adjoint (backward) plumes are applied to identify the spread of originating air masses in terms of horizontal and vertical extension, and the influence of precursor species. Flight patterns include 5 points of measurement along the transect on 21.06.2012 and the lowest (ca. 80m), highest (ca. 708m), and medium height (299 to 464m) of 7 vertical profiles on the 20.06.2012.

  1. An aerosol climatology for the Jungfraujoch, Part 1: Criteria for cloud presence and boundary layer influence

    NASA Astrophysics Data System (ADS)

    Herrmann, Erik; Weingartner, Ernest; Gysel, Martin; Bukowiecki, Nicolas; Hammer, Emanuel; Collaud Coen, Martine; Conen, Franz; Vuilleumier, Laurent; Baltensperger, Urs

    2014-05-01

    The high alpine research station at the Jungfraujoch in Switzerland is located at 3580 m asl. Depending on meteorological conditions, the station is in the planetary boundary layer or in the free troposphere; and often it is inside clouds. In one location, it is thus possible to study aerosols under very different conditions. These possibilities have been recognized early on, with aerosol measurements starting in 1995. Over the years, the instrumentation has been extended significantly, today including various measurements of aerosol optical properties (nephelometer, aethalometer, MAAP) as well as aerosol size distribution (SMPS, OPC, APS). Additionally, the station regularly hosts campaigns (e.g. CLACE) with a multitude of additional devices, mostly focusing on new particle formation, cloud condensation nuclei, and ice nuclei. However, there are no continuously operated direct measurements to determine whether the station is in the clouds or not, whether it is in the PBL or the free troposphere. As these are essential parameters to describe the aerosol observed at the station, we present approaches to describe them based on the observations available to us. The intuitive choices to look at in terms of clouds are relative humidity and dew point. When comparing dew point and ambient temperature, a clear criterion to identify clouds can be easily deducted. However, the determination of "no clouds" is more ambiguous. Based on longwave radiation measurements performed routinely at the site, it is possible to calculate the sky temperature, i.e. the temperature at the point of origin of the radiation. When within a cloud, the sky temperature should be identical or at least close to ambient temperature. The comparison of sky and ambient temperature shows two clear clusters which can be interpreted as "cloud" and "no cloud". One has to note that in case of inversion or clouds shortly above the research station, this approach will produce false positives. However, combining

  2. Resolution and Content Improvements to MISR Aerosol and Land Surface Products

    NASA Astrophysics Data System (ADS)

    Garay, M. J.; Bull, M. A.; Diner, D. J.; Hansen, E. G.; Kalashnikova, O. V.

    2015-12-01

    Since early 2000, the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA's Terra satellite has been providing operational Level 2 (swath-based) aerosol optical depth (AOD) and particle property retrievals at 17.6 km spatial resolution and atmospherically corrected land surface products at 1.1 km resolution. The performance of the aerosol product has been validated against ground-based Aerosol Robotic Network (AERONET) observations, model comparisons, and climatological assessments. This product has played a major role in studies of the impacts of aerosols on climate and air quality. The surface product has found a variety of uses, particularly at regional scales for assessing vegetation and land surface change. A major development effort has led to the release of an update to the operational (Version 22) MISR Level 2 aerosol and land surface retrieval products, which has been in production since December 2007. The new release is designated Version 23. The resolution of the aerosol product has been increased to 4.4 km, allowing more detailed characterization of aerosol spatial variability, especially near local sources and in urban areas. The product content has been simplified and updated to include more robust measures of retrieval uncertainty and other fields to benefit users. The land surface product has also been updated to incorporate the Version 23 aerosol product as input and to improve spatial coverage, particularly over mountainous terrain and snow/ice-covered surfaces. We will describe the major upgrades incorporated in Version 23 and present validation of the aerosol product against both the standard AERONET historical database, as well as high spatial density AERONET-DRAGON deployments. Comparisons will also be shown relative to the Version 22 aerosol and land surface products. Applications enabled by these product updates will be discussed.

  3. Observed perturbations of the Earth's Radiation Budget - A response to the El Chichon stratospheric aerosol layer?

    NASA Technical Reports Server (NTRS)

    Ardanuy, P. E.; Kyle, H. L.

    1986-01-01

    The Earth Radiation Budget experiment, launched aboard the Nimbus-7 polar-orbiting spacecraft in late 1978, has now taken over seven years of measurements. The dataset, which is global in coverage, consists of the individual components of the earth's radiation budget, including longwave emission, net radiation, and both total and near-infrared albedos. Starting some six months after the 1982 eruption of the El Chichon volcano, substantial long-lived positive shortwave irradiance anomalies were observed by the experiment in both the northern and southern polar regions. Analysis of the morphology of this phenomena indicates that the cause is the global stratospheric aerosol layer which formed from the cloud of volcanic effluents. There was little change in the emitted longwave in the polar regions. At the north pole the largest anomaly was in the near-infrared, but at the south pole the near UV-visible anomaly was larger. Assuming an exponential decay, the time constant for the north polar, near-infrared anomaly was 1.2 years. At mid- and low latitudes the effect of the El Chichon aerosol layer could not be separated from the strong reflected-shortwave and emitted-longwave perturbations issuing from the El Nino/Southern Oscillation event of 1982-83.

  4. Two MODIS Aerosol Products Over Ocean on the Terra and Aqua CERES SSF Datasets

    NASA Technical Reports Server (NTRS)

    Ignatov, Alexander; Minnis, Patrick; Loeb, Norman; Wielicki, Bruce; Miller, Walter; Sun-Mack, Sunny; Tanre, Didier; Remer, Lorraine; Laszlo, Istvan; Geier, Erika

    2004-01-01

    Over ocean, two aerosol products are reported on the Terra and Aqua CERES SSFs. Both are derived from MODIS, but using different sampling and aerosol algorithms. This study briefly summarizes these products, and compares using 2 weeks of global Terra data from 15-21 December 2000, and 1-7 June 2001.

  5. 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.

  6. VIIRS Aerosol Optical Depth (AOD) Products for Air Quality Applications

    NASA Astrophysics Data System (ADS)

    Huff, A. K.; Zhang, H.; Kondragunta, S.; Laszlo, I.

    2014-12-01

    The air quality community uses satellite aerosol optical depth (AOD) for a variety of applications, including daily air quality forecasting, retrospective event analysis, and justification for Exceptional Events. AOD is suitable for ambient air quality applications because is related to particulate matter (e.g., PM2.5) concentrations in the atmosphere; higher values of AOD correspond to higher concentrations of particulate matter. AOD is useful for identifying and tracking areas of high PM2.5 concentrations that correspond to air quality events, such as wildfires, dust storms, or haze episodes. Currently, the air quality community utilizes AOD from the MODIS instrument on NASA's polar-orbiting Terra and Aqua satellites and from NOAA's GOES geostationary satellites (e.g, GASP). The Visible Infrared Imaging Radiometer Suite (VIIRS) instrument on the Suomi-NPP satellite is making AOD measurements that are similar to MODIS AOD, but with higher spatial resolution. Two AOD products are available from VIIRS: the 750 m nadir resolution Intermediate Product (IP) and the 6 km resolution Environmental Data Record (EDR) product, which is aggregated from IP measurements. These VIIRS AOD products offer a substantial increase in spatial resolution compared to the MODIS AOD 3 km and 10 km AOD products, respectively. True color (RGB) imagery is also available from VIIRS as a decision aid for air quality applications. It serves as a complement to AOD measurements by providing visible information about areas of smoke, haze, and blowing dust in the atmosphere. Case studies of VIIRS AOD and RGB data for recent air quality events will be presented, with a focus on wildfires, and the relative pros and cons of the VIIRS AOD IP and EDR for air quality applications will be discussed in comparison to MODIS AOD products. Improvements to VIIRS aerosol products based on user feedback as part of the NOAA Satellite Air Quality Proving Ground (AQPG) will be outlined, and an overview of future

  7. A Comparison of Aerosol-Layer and Convective Boundary-Layer Structure over a Mountain Range during STAAARTE '97

    SciTech Connect

    De Wekker, Stephan; Steyn, D. G.; Nyeki, Stephan

    2004-11-01

    The temporal evolution and spatial structure of the aerosol layer (AL) height as observed with an airborne downlooking lidar over the Swiss Alps was investigated with a three dimensional mesoscale numerical model and a particle dispersion model. Convective boundary layer (CBL) heights were derived from the mesoscale model output, and the behavior of surface-released particles was investigated with the particle dispersion model. While a previous investigation, using data from the same field study, equated the observed AL height with the CBL height, the results of the current investigation indicate that there is a considerable difference between AL and CBL heights caused by mixing and transport processes between the CBL and the free atmosphere. CBL heights show a more terrain-following behavior and are lower than AL heights. We argue that processes causing the difference between AL and CBL heights are common over mountainous terrain and that the AL height is a length scale that needs t o be considered in air pollution studies in mountainous terrain.

  8. Extinction-to-Backscatter Ratios of Lofted Aerosol Layers Observed During the First Three Months of CALIPSO Measurements

    NASA Technical Reports Server (NTRS)

    Omar, Ali H.; Vaughan, Mark A.; Liu, Zhaoyan; Hu, Yongxiang; Reagan, John A.; Winker, David M.

    2007-01-01

    Case studies from the first three months of the Cloud and Aerosol Lidar and Infrared Pathfinder Spaceborne Observations (CALIPSO) measurements of lofted aerosol layers are analyzed using transmittance [Young, 1995] and two-wavelength algorithms [Vaughan et al., 2004] to determine the aerosol extinction-to-backscatter ratios at 532 and 1064 nm. The transmittance method requires clear air below the layer so that the transmittance through the layer can be determined. Suitable scenes are selected from the browse images and clear air below features is identified by low 532 nm backscatter signal and confirmed by low depolarization and color ratios. The transmittance and two-wavelength techniques are applied to a number of lofted layers and the extinction-to-backscatter ratios are compared with values obtained from the CALIPSO aerosol models [Omar et al., 2004]. The results obtained from these studies are used to adjust the aerosol models and develop observations based extinction-to-backscatter ratio look-up tables and phase functions. Values obtained by these techniques are compared to Sa determinations using other independent methods with a goal of developing probability distribution functions of aerosol type-specific extinction to backscatter ratios. In particular, the results are compared to values determined directly by the High Spectral Resolution Lidar (HSRL) during the CALIPSO CloudSat Validation Experiments (CCVEX) and Sa determined by the application of the two-wavelength lidar Constrained Ratio Aerosol Model-fit (CRAM) retrieval approach [Cattrall et al., 2005; Reagan et al., 2004] to the HSRL data. The results are also compared to values derived using the empirical relationship between the multiple-scattering fraction and the linear depolarization ratio by using Monte Carlo simulations of water clouds [Hu et al., 2006].

  9. Chemical analysis of aerosol in the Venusian cloud layer by reaction gas chromatography on board the Vega landers

    NASA Technical Reports Server (NTRS)

    Gelman, B. G.; Drozdov, Y. V.; Melnikov, V. V.; Rotin, V. A.; Khokhlov, V. N.; Bondarev, V. B.; Dolnikov, G. G.; Dyachkov, A. V.; Nenarokov, D. F.; Mukhin, L. M.

    1986-01-01

    The experiment on sulfuric acid aerosol determination in the Venusian cloud layer on board the Vega landers is described. An average content of sulfuric acid of approximately 1 mg/cu m was found for the samples taken from the atmosphere at heights from 63 to 48 km and analyzed with the SIGMA-3 chromatograph. Sulfur dioxide (SO2) was revealed in the gaseous sample at the height of 48 km. From the experimental results and blank run measurements, a suggestion is made that the Venusian cloud layer aerosol consists of more complicated particles than the sulfuric acid water solution does.

  10. Characterizing the formation of organic layers on the surface of inorganic/aqueous aerosols by Raman spectroscopy.

    PubMed

    Buajarern, Jariya; Mitchem, Laura; Reid, Jonathan P

    2007-11-22

    We demonstrate that nonlinear Raman spectroscopy coupled with aerosol optical tweezers can be used to probe the evolving phase partitioning in mixed organic/inorganic/aqueous aerosol droplets that adopt a core-shell structure in which the aqueous phase is coated in an organic layer. Specifically, we demonstrate that the characteristic fingerprint of wavelengths at which stimulated Raman scattering is observed can be used to assess the phase behavior of multiphase decane/aqueous sodium chloride droplets. Decane is observed to form a layer on the surface of the core aqueous droplet, and from the spectroscopic signature the aqueous core size can be determined with nanometer accuracy and the thickness of the decane layer with an accuracy of +/-8 nm. Further, the presence of the organic layer is observed to reduce the rate at which water evaporates from the core of the droplet with an increasing rate of evaporation observed with diminishing layer thickness.

  11. Characterizing the formation of organic layers on the surface of inorganic/aqueous aerosols by Raman spectroscopy.

    PubMed

    Buajarern, Jariya; Mitchem, Laura; Reid, Jonathan P

    2007-11-22

    We demonstrate that nonlinear Raman spectroscopy coupled with aerosol optical tweezers can be used to probe the evolving phase partitioning in mixed organic/inorganic/aqueous aerosol droplets that adopt a core-shell structure in which the aqueous phase is coated in an organic layer. Specifically, we demonstrate that the characteristic fingerprint of wavelengths at which stimulated Raman scattering is observed can be used to assess the phase behavior of multiphase decane/aqueous sodium chloride droplets. Decane is observed to form a layer on the surface of the core aqueous droplet, and from the spectroscopic signature the aqueous core size can be determined with nanometer accuracy and the thickness of the decane layer with an accuracy of +/-8 nm. Further, the presence of the organic layer is observed to reduce the rate at which water evaporates from the core of the droplet with an increasing rate of evaporation observed with diminishing layer thickness. PMID:17958403

  12. Characterizing the Asian Tropopause Aerosol Layer (ATAL) Using Satellite Observations, Balloon Measurements and a Chemical Transport Model

    NASA Technical Reports Server (NTRS)

    Fairlie, T. D.; Vernier, J.-P.; Liu, H.; Deshler, T.; Natarajan, M.; Bedka, K.; Wegner, T.; Baker, N.; Gadhavi, H.; Ratnam, M. V.; Jayaraman, A.; Pandit, A.; Raj, A.; Kumar, H.; Kumar, S.; Singh, A.; Stenchikov, G.; Wienhold, F.; Bian, J.

    2016-01-01

    Satellite observations and numerical modeling studies have demonstrated that the Asian Summer Monsoon (ASM) provide a conduit for gas-phase pollutants in south Asia to reach the lower stratosphere. Now, observations from the CALIPSO satellite have revealed the Asian Tropopause Aerosol Layer (ATAL), a summertime accumulation of aerosols in the upper troposphere and lower stratosphere (UTLS), associated with the ASM anticyclone. The ATAL has potential implications for regional cloud properties, climate, and chemical processes in the UTLS. Here, we show in situ measurements from balloon-borne instruments, aircraft, and satellite observations, together with trajectory and chemical transport model (CTM) simulations to explore the origin, composition, physical, and optical properties of aerosols in the ATAL. In particular, we show balloon-data from our BATAL-2015 field campaign to India and Saudi Arabia in summer 2015, which includes in situ backscatter measurements from COBALD instruments, and the first observations of size and volatility of aerosols in the ATAL layer using optical particle counters (OPCs). Back trajectory calculations initialized from CALIPSO observations point to deep convection over North India as a principal source of ATAL aerosols. Available aircraft observations suggest significant sulfur and carbonaceous components to the ATAL, which is supported by simulations using the GEOS-Chem CTM. Source elimination studies conducted with the GEOS-Chem indicate that ATAL aerosols originate primary from south Asian sources, in contrast with some earlier studies.

  13. Influence of anthropogenic aerosol deposition on the relationship between oceanic productivity and warming

    NASA Astrophysics Data System (ADS)

    Wang, Rong; Balkanski, Yves; Bopp, Laurent; Aumont, Olivier; Boucher, Olivier; Ciais, Philippe; Gehlen, Marion; Peñuelas, Josep; Ethé, Christian; Hauglustaine, Didier; Li, Bengang; Liu, Junfeng; Zhou, Feng; Tao, Shu

    2015-12-01

    Satellite data and models suggest that oceanic productivity is reduced in response to less nutrient supply under warming. In contrast, anthropogenic aerosols provide nutrients and exert a fertilizing effect, but its contribution to evolution of oceanic productivity is unknown. We simulate the response of oceanic biogeochemistry to anthropogenic aerosols deposition under varying climate from 1850 to 2010. We find a positive response of observed chlorophyll to deposition of anthropogenic aerosols. Our results suggest that anthropogenic aerosols reduce the sensitivity of oceanic productivity to warming from -15.2 ± 1.8 to -13.3 ± 1.6 Pg C yr-1 °C-1 in global stratified oceans during 1948-2007. The reducing percentage over the North Atlantic, North Pacific, and Indian Oceans reaches 40, 24, and 25%, respectively. We hypothesize that inevitable reduction of aerosol emissions in response to higher air quality standards in the future might accelerate the decline of oceanic productivity per unit warming.

  14. Elevated aerosol layers modify the O2-O2 absorption measured by ground-based MAX-DOAS

    NASA Astrophysics Data System (ADS)

    Ortega, Ivan; Berg, Larry K.; Ferrare, Richard A.; Hair, Johnathan W.; Hostetler, Chris A.; Volkamer, Rainer

    2016-06-01

    The oxygen collisional complex (O2-O2, or O4) is a greenhouse gas, and a calibration trace gas used to infer aerosol and cloud properties by Differential Optical Absorption Spectroscopy (DOAS). Recent reports suggest the need for an O4 correction factor (CFO4) when comparing simulated and measured O4 differential slant column densities (dSCD) by passive DOAS. We investigate the sensitivity of O4 dSCD simulations at ultraviolet (360 nm) and visible (477 nm) wavelengths towards separately measured aerosol extinction profiles. Measurements were conducted by the University of Colorado 2D-MAX-DOAS instrument and NASA's multispectral High Spectral Resolution Lidar (HSRL-2) during the Two Column Aerosol Project (TCAP) at Cape Cod, MA in July 2012. During two case study days with (1) high aerosol load (17 July, AOD~0.35 at 477 nm), and (2) near molecular scattering conditions (22 July, AOD<0.10 at 477 nm) the measured and calculated O4 dSCDs agreed within 6.4±0.4% (360 nm) and 4.7±0.6% (477 nm) if the HSRL-2 profiles were used as input to the calculations. However, if in the calculations the aerosol is confined to the surface layer (while keeping AOD constant) we find 0.53aerosol layers, unless accounted for, can cause negative bias in the simulated O4 dSCDs that can explain CFO4. The air density and aerosol profile aloft needs to be taken into account when interpreting the O4 from ground-based MAX-DOAS. Opportunities to identify and better characterize these elevated layers are also discussed.

  15. The relationship of boundary layer clouds in the tropical southeast Atlantic to absorbing aerosols, meteorology and climate change

    NASA Astrophysics Data System (ADS)

    Zuidema, P.; Adebiyi, A. A.; Ramajiguru, L.

    2015-12-01

    Ascension Island, a remote island located in the middle of the Atlantic Ocean within the trade-wind region oat 8S, 14.5W, experiences the outflow of biomass-burning aerosols from continental Africa, over 2000 km away, from July through November, peaking in August and September. The shortwave-absorbing free-tropospheric aerosols, located in a region of high solar irradiance, provide a climate warming that is poorly represented in global aerosol climate models. The low clouds can respond to the smoke layer in myriad possible ways that are not yet well-documented. The shortwave-warming can stabilize the free-troposphere, enhancing the low cloud fraction. The deepening boundary layer and subsiding smoke layer also increase the likelihood of aerosol-cloud microphysical interactions. Interest in this climate regime is supporting an observational strategy of a year-long DOE ARM Mobile Facility deployment to Ascension (Layered Atlantic Smoke Interactions with Clouds, or LASIC), and an NSF aircraft campaign (ObservatioNs of Fire's Impact on the southeast atlantic REgion, or ONFIRE) based on Sao Tome Island. These campaigns will be integrated with NASA, UK and African activities sharing similar goals based further south in Namibia. Initial analysis is distinguishing meteorology from aerosol impacts on the boundary layer cloud fields. The forward trajectories of emissions from over 24,000 fire sources on continental Africa show that a free-tropospheric jet can advect aerosols to above Ascension island in just one-two days. The fast transport time encourages retention of signatures of the fire sources, in particular the radiatively-crucial single-scattering albedo value. Thereafter, a deep land-based anticyclonic high recirculates over one-third of these trajectories back to the African continent, explaining the widespread extent of the aerosol layer. The free-tropospheric jet also reduces the mean atmospheric subsidence independently of shortwave absorption by the aerosols

  16. Lidar determination of winds by aerosol inhomogeneities: motion velocity in the planetary boundary layer.

    PubMed

    Kolev, I; Parvanov, O; Kaprielov, B

    1988-06-15

    The paper presents results from lidar measurements of wind velocity in the planetary boundary layer using correlation data processing. Two lidars are used in our experiments: a ruby lidar operating along slant paths and a YAG:Nd lidar operating for near vertical sounding used by us for the first time. On the basis of our experience the optimal sizes of aerosol inhomogeneities (30-300 m), the duration of the experiments (2-10 min), and the repetition rate of laser shots (fractions of hertz to several hertz) are determined. The results are compared to independent data obtained from anemometer measurements, theodolite- and radar-tracked pilot balloons. The range of differences is ~1-2 m/s in speed and 10-15 degrees in direction. Preliminary results from the use of lidar data to remotely sound the wind speed for various atmospheric stratifications and synoptic situations are described as well. PMID:20531786

  17. Study of the efficacy of aerosol versus nonaerosol laundry products. Final report

    SciTech Connect

    Boggs, R.R.; Belmont, B.

    1987-10-01

    The California Air Resources Board estimates that 6.6 tons of photochemically reactive organic compounds (PROC) are released into the environment in California every day because of the use of aerosol laundry products. The project studied the efficacy, ease of product use, and PROC content for three major brands of pre-wash stain removers in available product forms and for five starch products in their available product forms. Efficacy of pre-wash products was generally found to be limited. They were particularly useful for oil and ball point ink removal. Aerosols were found to be slightly superior. PROC content varied from 16-76% on aerosols; none was found in nonaerosols. Aerosols were found to be slightly easier to use by the laboratory investigator. For starches, on synthetic fabrics Faultless aerosol was found to be superior. For natural fabrics, results were mixed. Efficacy per unit cost was found to be high for bulk starches. PROC content for the two aerosols was 5.8% for Faultless and 8.5% for Niagra. Aerosols were easiest to use and bulk products rather difficult to use.

  18. Utilization of O4 slant column density to derive aerosol layer height from a spaceborne UV-visible hyperspectral sensor: sensitivity and case study

    NASA Astrophysics Data System (ADS)

    Park, S. S.; Kim, J.; Lee, H.; Torres, O.; Lee, K.-M.; Lee, S. D.

    2015-03-01

    The sensitivities of oxygen-dimer (O4) slant column densities (SCDs) to changes in aerosol layer height are investigated using simulated radiances by a radiative transfer model, Linearized Discrete Ordinate Radiative Transfer (LIDORT), and Differential Optical Absorption Spectroscopy (DOAS) technique. The sensitivities of the O4 SCDs to aerosol types and optical properties are also evaluated and compared. Among the O4 absorption bands at 340, 360, 380, and 477 nm, the O4 absorption band at 477 nm is found to be the most suitable to retrieve the aerosol effective height. However, the O4 SCD at 477 nm is significantly influenced not only by the aerosol layer effective height but also by aerosol vertical profiles, optical properties including single scattering albedo (SSA), aerosol optical depth (AOD), and surface albedo. Overall, the error of the retrieved aerosol effective height is estimated to be 414 m (16.5%), 564 m (22.4%), and 1343 m (52.5%) for absorbing, dust, and non-absorbing aerosol, respectively, assuming knowledge on the aerosol vertical distribution type. Using radiance data from the Ozone Monitoring Instrument (OMI), a new algorithm is developed to derive the aerosol effective height over East Asia after the determination of the aerosol type and AOD from the MODerate resolution Imaging Spectroradiometer (MODIS). The retrieved aerosol effective heights are lower by approximately 300 m (27 %) compared to those obtained from the ground-based LIDAR measurements.

  19. Secondary organic aerosol formation of relevance to the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Cai, Xuyi

    The chlorine atom (Cl) is a potential oxidant of volatile organic compounds (VOCs) in the atmosphere and is hypothesized to lead to secondary organic aerosol (SOA) formation in coastal areas. The purpose of this dissertation is to test this hypothesis and quantify the SOA formation potentials of some representative biogenic and anthropogenic hydrocarbons when oxidized by Cl in laboratory chamber experiments. The chosen model compounds for biogenic and anthropogenic hydrocarbons in this study are three monoterpenes (alpha-pinene, beta-pinene, and d-limonene) and two aromatics (m-xylene and toluene), respectively. Results indicate that the oxidation of these monoterpenes and aromatics generates significant amounts of aerosol. The SOA yields of alpha-pinene, beta-pinene, and d-limonene obtained in this study are comparable to those when they are oxidized by ozone, by nitrate radical, and in photooxidation scenarios. For aerosol mass up to 30.0 mug m-3, their yields reach approximately 0.20, 0.20, and 0.30, respectively. The SOA yields for m-xylene and toluene are found to be in the range of 0.035 to 0.12 for aerosol concentrations up to 19 mug m-3. For d-limonene and toluene, data indicate two yield curves that depend on the initial concentration ratios of Cl precursor to hydrocarbon hydrocarbon. Zero-dimensional calculations based on these yields show that SOA formation from the five model compounds when oxidized by Cl in the marine boundary layer could be a significant source of SOA in the early morning. In addition, the mechanistic reaction pathways for Cl oxidation of alpha-pinene, beta-pinene, d-limonene, and toluene with Cl have been developed within the framework of the Caltech Atmospheric Chemistry Mechanisms (CACM). Output from the developed mechanisms is combined with an absorptive partitioning model to predict precursor decay curves and time-dependent SOA concentrations in experiments. Model calculations are able to match (in general within general +/- 50

  20. Aerosol-Jet-Printing silicone layers and electrodes for stacked dielectric elastomer actuators in one processing device

    NASA Astrophysics Data System (ADS)

    Reitelshöfer, Sebastian; Göttler, Michael; Schmidt, Philip; Treffer, Philipp; Landgraf, Maximilian; Franke, Jörg

    2016-04-01

    In this contribution we present recent findings of our efforts to qualify the so called Aerosol-Jet-Printing process as an additive manufacturing approach for stacked dielectric elastomer actuators (DEA). With the presented system we are able to print the two essential structural elements dielectric layer and electrode in one machine. The system is capable of generating RTV-2 silicone layers made of Wacker Elastosil P 7670. Therefore, two aerosol streams of both precursor components A and B are generated in parallel and mixed in one printing nozzle that is attached to a 4-axis kinematic. At maximum speed the printing of one circular Elastosil layer with a calculated thickness of 10 μm and a diameter of 1 cm takes 12 seconds while the process keeps stable for 4.5 hours allowing a quite high overall material output and the generation of numerous silicone layers. By adding a second printing nozzle and the infrastructure to generate a third aerosol, the system is also capable of printing inks with conductive particles in parallel to the silicone. We have printed a reduced graphene oxide (rGO) ink prepared in our lab to generate electrodes on VHB 4905, Elastosil foils and finally on Aerosol-Jet-Printed Elastosil layers. With rGO ink printed on Elastosil foil, layers with a 4-point measured sheet resistance as low as 4 kΩ can be realized leaving room for improving the electrode printing time, which at the moment is not as good as the quite good time-frame for printing the silicone layers. Up to now we have used the system to print a fully functional two-layer stacked DEA to demonstrate the principle of continuously 3D printing actuators.

  1. Particle Property Data Quality Flags for the MISR Aerosol Product

    NASA Astrophysics Data System (ADS)

    Gaitley, B. J.; Kahn, R. A.; Garay, M. J.

    2013-12-01

    The MISR instrument aboard the NASA Earth Observing System's Terra satellite has the unique capability to retrieve aerosol properties under favorable conditions. General aerosol type retrieval quality guidelines are provided in the MISR Data Quality Statement and related publications. The retrieved value of aerosol type is more sensitive to scene conditions than aerosol optical depth, and more difficult to validate, as there is very little coincident aerosol type validation data. Here we report on the steps we are taking to provide an aerosol-type data quality flag, to be provided with each individual retrieval result. Due to the lack of validation data for comparison, our main approach is to evaluate the self-consistency of aerosol type retrieval values for regions where particular aerosol types are known to dominate. Some factors affecting aerosol type retrieval quality that can be assessed pre-retrieval are the number of MISR cameras available, the range of scattering angles viewed, and surface conditions such as shallow water or seasonal coastal runoff. Factors that must be assessed post-retrieval include values of retrieved aerosol optical depth and the number and type of mixtures successfully passing the MISR algorithm acceptance criteria. Regional monthly plots with MISR measurements binned at 0.5 degree resolution and color-coded stratification of one or more parameters are the main tools for identifying locations and times where different aerosol types are retrieved. The statistics of individual MISR values such as mid-visible AOD, number and type of mixtures passing, number of cameras used, the range and maximum scattering angles, are studied as joint distributions on a region-by-region basis. From these, a synthesis of the self-consistency and agreement with expectation is made, effectively indicating the quality of the aerosol type constrains to the extent possible, and thresholds for assigning quality flags are assessed. Multiple-month summaries

  2. Evaluation of the Moderate Resolution Imaging Spectroradiometer aerosol products at two Aerosol Robotic Network stations in China

    NASA Astrophysics Data System (ADS)

    Mi, Wen; Li, Zhanqing; Xia, Xiangao; Holben, Brent; Levy, Robert; Zhao, Fengsheng; Chen, Hongbin; Cribb, Maureen

    2007-11-01

    Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol products have been used to address aerosol climatic issues in many parts of the world, but their quality has yet to be determined over China. This paper presents a thorough evaluation of aerosol optical depth (AOD) data retrieved from MODIS collections 4 (C004) and 5 (C005) at two AERONET sites in northern and southeastern China. Established under the aegis of the East Asian Study of Tropospheric Aerosols: An International Regional Experiment (EAST-AIRE) project, the two sites, Xianghe and Taihu, have distinct ecosystems and climate regimes, resulting in differences in retrieval performance. At the rural northeastern site (Xianghe), MODIS C004 retrievals generally overestimate AOD at 550 nm during clean days, with the largest errors occurring during winter. In the warm and humid regions of southeastern China (Taihu), MODIS C004 retrievals overestimate AOD throughout the year. The systematic error at Xianghe is primarily due to the fixed surface reflectance ratio, while as the error at Taihu is mainly caused by the choice of the single scattering albedo (SSA) for the fine model aerosols. Both problems are alleviated considerably in the C005. The comparisons between C005 retrievals and AERONET data show much higher correlation coefficient, lower offset and a slope closer to unity. Also, the variability of AOD retrieval among neighboring pixels is reduced by several factors. The strong overestimation problem at small AOD values was fixed by using dynamic reflectance ratios that vary with the vegetation index and scattering angle. However, significant uncertainties remain because of the use of highly simplified aerosol models.

  3. Variability of the stratospheric aerosol layer due to volcanic eruptions in the last decade: Odin-OSIRIS measurements

    NASA Astrophysics Data System (ADS)

    Bourassa, A. E.; Degenstein, D. A.

    2011-12-01

    Recently reported measurements show that an increasing trend in the stratospheric aerosol layer during the last decade can be attributed in a large part to a series of relatively minor lower stratospheric volcanic eruptions. The limb scatter measurements of the stratospheric aerosol extinction coefficient made by the OSIRIS instrument on the Odin satellite show evidence of several eruptions, both tropical and at high latitude, which have a significant impact on the stratospheric aerosol layer. The extent and duration of the stratospheric impact of these eruptions is explored in this work. The measurements, which have daily, nearly global coverage, show that these minor eruptions, particularly those in the tropics, have increased the magnitude of stratospheric aerosol optical depth by more than 5% per year at mid-latitudes. Additionally, the measurements show that a measureable increase in aerosol optical depth is observed in the tropics in the months following the eruption of two high latitude eruptions, namely Kasatochi Volcano in 2008 and Sarychev Peak in 2009.

  4. MODIS 3 Km Aerosol Product: Applications over Land in an Urban/suburban Region

    NASA Technical Reports Server (NTRS)

    Munchak, L. A.; Levy, R. C.; Mattoo, S.; Remer, L. A.; Holben, B. N.; Schafer, J. S.; Hostetler, C. A.; Ferrare, R. A.

    2013-01-01

    MODerate resolution Imaging Spectroradiometer (MODIS) instruments aboard the Terra and Aqua satellites have provided a rich dataset of aerosol information at a 10 km spatial scale. Although originally intended for climate applications, the air quality community quickly became interested in using the MODIS aerosol data. However, 10 km resolution is not sufficient to resolve local scale aerosol features. With this in mind, MODIS Collection 6 is including a global aerosol product with a 3 km resolution. Here, we evaluate the 3 km product over the Baltimore/Washington D.C., USA, corridor during the summer of 2011, by comparing with spatially dense data collected as part of the DISCOVER-AQ campaign these data were measured by the NASA Langley Research Center airborne High Spectral Resolution Lidar (HSRL) and a network of 44 sun photometers (SP) spaced approximately 10 km apart. The HSRL instrument shows that AOD can vary by up to 0.2 within a single 10 km MODIS pixel, meaning that higher resolution satellite retrievals may help to characterize aerosol spatial distributions in this region. Different techniques for validating a high-resolution aerosol product against SP measurements are considered. Although the 10 km product is more statistically reliable than the 3 km product, the 3 km product still performs acceptably, with more than two-thirds of MODIS/SP collocations falling within the expected error envelope with high correlation (R > 0.90). The 3 km product can better resolve aerosol gradients and retrieve closer to clouds and shorelines than the 10 km product, but tends to show more significant noise especially in urban areas. This urban degradation is quantified using ancillary land cover data. Overall, we show that the MODIS 3 km product adds new information to the existing set of satellite derived aerosol products and validates well over the region, but due to noise and problems in urban areas, should be treated with some degree of caution.

  5. Aerosols and their influence on radiation partitioning and savanna productivity in northern Australia

    SciTech Connect

    Kanniah, K. D.; Beringer, J.; Tapper, N. J.; Long, Charles N.

    2010-05-01

    We investigated the effect of aerosols and clouds on the Net Ecosystem Productivity (NEP) of savannas in northern Australia using aerosol optical depth, clouds and radiation data from the Atmospheric Radiation Measurement (ARM) site in Darwin and carbon flux data measured from eddy covariance techniques from a site at Howard Springs, 35km southeast of Darwin. Generally we found that the concentration of aerosols in this region was relatively low than observed at other sites, therefore the proportion of diffuse radiation reaching the earths surface was only ~ 30%. As a result, we observed only a modest change in carbon uptake under aerosol laden skies and there was no significant difference for dry season Radiation Use Efficiency (RUE) between clear sky, aerosols or thin clouds. On the other hand thick clouds in the wet season produce much more diffuse radiation than aerosols or thin clouds and therefore the initial canopy quantum efficiency was seen to increase 45 and 2.5 times more than under thin clouds and aerosols respectively. The normalized carbon uptake under thick clouds is 57% and 50% higher than under aerosols and thin clouds respectively even though the total irradiance received under thick clouds was reduced 59% and 50% than under aerosols and thin clouds respectively. However, reduction in total irradiance decreases the mean absolute carbon uptake as much as 22% under heavy cloud cover compared to thin clouds or aerosols. Thus, any increase in aerosol concentration or cloud cover that can enhance the diffuse component may have large impacts on productivity in this region.

  6. A simple method to compute the change in earth-atmosphere radiative balance due to a stratospheric aerosol layer

    NASA Technical Reports Server (NTRS)

    Lenoble, J.; Tanre, D.; Deschamps, P. Y.; Herman, M.

    1982-01-01

    A computer code was developed in terms of a three-layer model for the earth-atmosphere system, using a two-stream approximation for the troposphere and stratosphere. The analysis was limited to variable atmosphere loading by solar radiation over an unperturbed section of the atmosphere. The scattering atmosphere above a Lambertian ground layer was considered in order to derive the planar albedo and the spherical albedo. Attention was given to the influence of the aerosol optical thickness in the stratosphere, the single scattering albedo and asymmetry factor, and the sublayer albedo. Calculations were performed of the zonal albedo and the planetary radiation balance, taking into account a stratospheric aerosol layer containing H2SO4 droplets and volcanic ash. The resulting ground temperature disturbance was computed using a Budyko (1969) climate model. Local decreases in the albedo in the summer were observed in high latitudes, implying a heating effect of the aerosol. An accompanying energy loss of 23-27 W/sq m was projected, which translates to surface temperature decreases of either 1.1 and 0.45 C, respectively, for background and volcanic aerosols.

  7. Utilization of O4 slant column density to derive aerosol layer height from a space-borne UV-visible hyperspectral sensor: sensitivity and case study

    NASA Astrophysics Data System (ADS)

    Park, Sang Seo; Kim, Jhoon; Lee, Hanlim; Torres, Omar; Lee, Kwang-Mog; Lee, Sang Deok

    2016-02-01

    The sensitivities of oxygen-dimer (O4) slant column densities (SCDs) to changes in aerosol layer height are investigated using the simulated radiances by a radiative transfer model, the linearized pseudo-spherical vector discrete ordinate radiative transfer (VLIDORT), and the differential optical absorption spectroscopy (DOAS) technique. The sensitivities of the O4 index (O4I), which is defined as dividing O4 SCD by 1040 molecules2 cm-5, to aerosol types and optical properties are also evaluated and compared. Among the O4 absorption bands at 340, 360, 380, and 477 nm, the O4 absorption band at 477 nm is found to be the most suitable to retrieve the aerosol effective height. However, the O4I at 477 nm is significantly influenced not only by the aerosol layer effective height but also by aerosol vertical profiles, optical properties including single scattering albedo (SSA), aerosol optical depth (AOD), particle size, and surface albedo. Overall, the error of the retrieved aerosol effective height is estimated to be 1276, 846, and 739 m for dust, non-absorbing, and absorbing aerosol, respectively, assuming knowledge on the aerosol vertical distribution shape. Using radiance data from the Ozone Monitoring Instrument (OMI), a new algorithm is developed to derive the aerosol effective height over East Asia after the determination of the aerosol type and AOD from the MODerate resolution Imaging Spectroradiometer (MODIS). About 80 % of retrieved aerosol effective heights are within the error range of 1 km compared to those obtained from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) measurements on thick aerosol layer cases.

  8. Utilization of O4 Slant Column Density to Derive Aerosol Layer Height from a Space-Borne UV-Visible Hyperspectral Sensor: Sensitivity and Case Study

    NASA Technical Reports Server (NTRS)

    Park, Sang Seo; Kim, Jhoon; Lee, Hanlim; Torres, Omar; Lee, Kwang-Mog; Lee, Sang Deok

    2016-01-01

    The sensitivities of oxygen-dimer (O4) slant column densities (SCDs) to changes in aerosol layer height are investigated using the simulated radiances by a radiative transfer model, the linearized pseudo-spherical vector discrete ordinate radiative transfer (VLIDORT), and the differential optical absorption spectroscopy (DOAS) technique. The sensitivities of the O4 index (O4I), which is defined as dividing O4 SCD by 10(sup 40) molecules (sup 2) per centimeters(sup -5), to aerosol types and optical properties are also evaluated and compared. Among the O4 absorption bands at 340, 360, 380, and 477 nanometers, the O4 absorption band at 477 nanometers is found to be the most suitable to retrieve the aerosol effective height. However, the O4I at 477 nanometers is significantly influenced not only by the aerosol layer effective height but also by aerosol vertical profiles, optical properties including single scattering albedo (SSA), aerosol optical depth (AOD), particle size, and surface albedo. Overall, the error of the retrieved aerosol effective height is estimated to be 1276, 846, and 739 meters for dust, non-absorbing, and absorbing aerosol, respectively, assuming knowledge on the aerosol vertical distribution shape. Using radiance data from the Ozone Monitoring Instrument (OMI), a new algorithm is developed to derive the aerosol effective height over East Asia after the determination of the aerosol type and AOD from the MODerate resolution Imaging Spectroradiometer (MODIS). About 80 percent of retrieved aerosol effective heights are within the error range of 1 kilometer compared to those obtained from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) measurements on thick aerosol layer cases.

  9. Fully Automated Detection of Cloud and Aerosol Layers in the CALIPSO Lidar Measurements

    NASA Technical Reports Server (NTRS)

    Vaughan, Mark A.; Powell, Kathleen A.; Kuehn, Ralph E.; Young, Stuart A.; Winker, David M.; Hostetler, Chris A.; Hunt, William H.; Liu, Zhaoyan; McGill, Matthew J.; Getzewich, Brian J.

    2009-01-01

    Accurate knowledge of the vertical and horizontal extent of clouds and aerosols in the earth s atmosphere is critical in assessing the planet s radiation budget and for advancing human understanding of climate change issues. To retrieve this fundamental information from the elastic backscatter lidar data acquired during the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission, a selective, iterated boundary location (SIBYL) algorithm has been developed and deployed. SIBYL accomplishes its goals by integrating an adaptive context-sensitive profile scanner into an iterated multiresolution spatial averaging scheme. This paper provides an in-depth overview of the architecture and performance of the SIBYL algorithm. It begins with a brief review of the theory of target detection in noise-contaminated signals, and an enumeration of the practical constraints levied on the retrieval scheme by the design of the lidar hardware, the geometry of a space-based remote sensing platform, and the spatial variability of the measurement targets. Detailed descriptions are then provided for both the adaptive threshold algorithm used to detect features of interest within individual lidar profiles and the fully automated multiresolution averaging engine within which this profile scanner functions. The resulting fusion of profile scanner and averaging engine is specifically designed to optimize the trade-offs between the widely varying signal-to-noise ratio of the measurements and the disparate spatial resolutions of the detection targets. Throughout the paper, specific algorithm performance details are illustrated using examples drawn from the existing CALIPSO dataset. Overall performance is established by comparisons to existing layer height distributions obtained by other airborne and space-based lidars.

  10. Characterization of particulate products for aging of ethylbenzene secondary organic aerosol in the presence of ammonium sulfate seed aerosol.

    PubMed

    Huang, Mingqiang; Zhang, Jiahui; Cai, Shunyou; Liao, Yingmin; Zhao, Weixiong; Hu, Changjin; Gu, Xuejun; Fang, Li; Zhang, Weijun

    2016-09-01

    Aging of secondary organic aerosol (SOA) particles formed from OH- initiated oxidation of ethylbenzene in the presence of high mass (100-300μg/m(3)) concentrations of (NH4)2SO4 seed aerosol was investigated in a home-made smog chamber in this study. The chemical composition of aged ethylbenzene SOA particles was measured using an aerosol laser time-of-flight mass spectrometer (ALTOFMS) coupled with a Fuzzy C-Means (FCM) clustering algorithm. Experimental results showed that nitrophenol, ethyl-nitrophenol, 2,4-dinitrophenol, methyl glyoxylic acid, 5-ethyl-6-oxo-2,4-hexadienoic acid, 2-ethyl-2,4-hexadiendioic acid, 2,3-dihydroxy-5-ethyl-6-oxo-4-hexenoic acid, 1H-imidazole, hydrated N-glyoxal substituted 1H-imidazole, hydrated glyoxal dimer substituted imidazole, 1H-imidazole-2-carbaldehyde, N-glyoxal substituted hydrated 1H-imidazole-2-carbaldehyde and high-molecular-weight (HMW) components were the predominant products in the aged particles. Compared to the previous aromatic SOA aging studies, imidazole compounds, which can absorb solar radiation effectively, were newly detected in aged ethylbenzene SOA in the presence of high concentrations of (NH4)2SO4 seed aerosol. These findings provide new information for discussing aromatic SOA aging mechanisms. PMID:27593289

  11. Controls on aerosol wet deposition from satellite-based (re-)analysis products

    NASA Astrophysics Data System (ADS)

    Chuang, P. Y.

    2015-12-01

    Aerosol wet deposition is the key aerosol loss mechanism globally, yet is not well-understood relative to aerosol sources and transformations. The difficulty in generating appropriate observational data sets is one important barrier to the study of aerosol wet removal. In this study, we combine two independent products based on satellite measurements. Aerosol optical depth (AOD) is obtained from the ECMWF Monitoring Atmospheric Composition and Climate (MACC) project, which is a re-analysis product that assimilates MODIS-retrieved aerosol optical depth. Rainfall is obtained from the Tropical Rainfall Measurement Mission (TRMM) Multi-satellite Precipitation Analysis version 7 (TMPA-7). The latter product is available only from 50°N to 50°S, which sets our region of study. The data used is from 2011-12, is averaged to 6-hr intervals and has a horizontal resolution of 0.25°x0.25°. Our approach involves constructing a Lagrangian advection scheme that predicts aerosol AOD at the next time step (i.e. 6 hr in the future) based on current time step AOD and winds, and neglecting all aerosol sources and sinks. Predicted AOD is then compared with MACC reanalysis AOD conditioned on Lagrangian parcels that experienced rainfall during that interval, with AOD decreases attributed to wet deposition. Aerosol wet deposition is often parameterized in models as a function of rainfall rate using a power law. We evaluate the validity of such a power law relationship, and, when valid, compute the power law exponent globally, and by region (including continental and maritime locations) to reveal seasonal and geographic variability. Assuming precipitation is modulated by aerosol, at least in some regimes, then it follows that wet deposition also depends on AOD, and we quantify the strength of this coupling. This same approach could be used to study wet deposition of trace gases such as CO and ozone, as these are also available from the MACC re-analysis.

  12. Aerosol Optical Depth Value-Added Product Report

    SciTech Connect

    Koontz, A; Hodges, G; Barnard, J; Flynn, C; Michalsky, J

    2013-03-17

    This document describes the process applied to retrieve aerosol optical depth (AOD) from multifilter rotating shadowband radiometers (MFRSR) and normal incidence multifilter radiometers (NIMFR) operated at the ARM Climate Research Facility’s ground-based facilities.

  13. Science verification of operational aerosol and cloud products for TROPOMI on Sentinel-5 precursor

    NASA Astrophysics Data System (ADS)

    Lelli, Luca; Gimeno-Garcia, Sebastian; Sanders, Abram; Sneep, Maarten; Rozanov, Vladimir V.; Kokhanvosky, Alexander A.; Loyola, Diego; Burrows, John P.

    2016-04-01

    With the approaching launch of the Sentinel-5 precursor (S-5P) satellite, scheduled by mid 2016, one preparatory task of the L2 working group (composed by the Institute of Environmental Physics IUP Bremen, the Royal Netherlands Meteorological Institute KNMI De Bilt, and the German Aerospace Center DLR Oberpfaffenhofen) has been the assessment of biases among aerosol and cloud products, that are going to be inferred by the respective algorithms from measurements of the platform's payload TROPOspheric Monitoring Instrument (TROPOMI). The instrument will measure terrestrial radiance with varying moderate spectral resolutions from the ultraviolet throughout the shortwave infrared. Specifically, all the operational and verification algorithms involved in this comparison exploit the sensitivity of molecular oxygen absorption (the A-band, 755-775 nm, with a resolution of 0.54 nm) to changes in optical and geometrical parameters of tropospheric scattering layers. Therefore, aerosol layer height (ALH) and thickness (AOT), cloud top height (CTH), thickness (COT) and albedo (CA) are the targeted properties. First, the verification of these properties has been accomplished upon synchronisation of the respective forward radiative transfer models for a variety of atmospheric scenarios. Then, biases against independent techniques have been evaluated with real measurements of selected GOME-2 orbits. Global seasonal bias assessment has been carried out for CTH, CA and COT, whereas the verification of ALH and AOT is based on the analysis of the ash plume emitted by the icelandic volcanic eruption Eyjafjallajökull in May 2010 and selected dust scenes off the Saharan west coast sensed by SCIAMACHY in year 2009.

  14. Air Quality Monitoring and Forecasting Applications of Suomi NPP VIIRS Aerosol Products

    NASA Astrophysics Data System (ADS)

    Kondragunta, Shobha

    The Suomi National Polar-orbiting Partnership (NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) instrument was launched on October 28, 2011. It provides Aerosol Optical Thickness (AOT) at two different spatial resolutions: a pixel level (~750 m at nadir) product called the Intermediate Product (IP) and an aggregated (~6 km at nadir) product called the Environmental Data Record (EDR), and a Suspended Matter (SM) EDR that provides aerosol type (dust, smoke, sea salt, and volcanic ash) information. An extensive validation of VIIRS best quality aerosol products with ground based L1.5 Aerosol Robotic NETwork (AERONET) data shows that the AOT EDR product has an accuracy/precision of -0.01/0.11 and 0.01/0.08 over land and ocean respectively. Globally, VIIRS mean AOT EDR (0.20) is similar to Aqua MODIS (0.16) with some important regional and seasonal differences. The accuracy of the SM product, however, is found to be very low (20 percent) when compared to Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) and AERONET. Several algorithm updates which include a better approach to retrieve surface reflectance have been developed for AOT retrieval. For dust aerosol type retrieval, a new approach that takes advantage of spectral dependence of Rayleigh scattering, surface reflectance, dust absorption in the deep blue (412 nm), blue (440 nm), and mid-IR (2.2 um) has been developed that detects dust with an accuracy of ~80 percent. For smoke plume identification, a source apportionment algorithm that combines fire hot spots with AOT imagery has been developed that provides smoke plume extent with an accuracy of ~70 percent. The VIIRS aerosol products will provide continuity to the current operational use of aerosol products from Aqua and Terra MODIS. These include aerosol data assimilation in Naval Research Laboratory (NRL) global aerosol model, verification of National Weather Service (NWS) dust and smoke forecasts, exceptional events monitoring by different states

  15. Fission product partitioning in aerosol release from simulated spent nuclear fuel

    NASA Astrophysics Data System (ADS)

    Di Lemma, F. G.; Colle, J. Y.; Rasmussen, G.; Konings, R. J. M.

    2015-10-01

    Aerosols created by the vaporization of simulated spent nuclear fuel (simfuel) were produced by laser heating techniques and characterised by a wide range of post-analyses. In particular attention has been focused on determining the fission product behaviour in the aerosols, in order to improve the evaluation of the source term and consequently the risk associated with release from spent fuel sabotage or accidents. Different simulated spent fuels were tested with burn-up up to 8 at. %. The results from the aerosol characterisation were compared with studies of the vaporization process by Knudsen Effusion Mass Spectrometry and thermochemical equilibrium calculations. These studies permit an understanding of the aerosol gaseous precursors and the gaseous reactions taking place during the aerosol formation process.

  16. The Remote Sensing of Mineral Aerosols and their Impact on Phytoplankton Productivity

    NASA Technical Reports Server (NTRS)

    Tindale, Neil W.

    1997-01-01

    The overall objective of this experiment was to test the iron hypothesis does the addition of iron to nutrient rich surface waters enhance productivity? Our specific objectives in this experiment included sampling and studying the marine aerosol size and type (which are related to chemical reactivity) during the PlumEx cruise to determine the importance of local (Galapagos Islands) versus long-range sources of atmospheric material. Detailed results of single particle analysis of our samples are being prepared for publication in two papers. We collect aerosol samples and they have been analyzed for trace metals and other elements. We are mapped aerosol distribution and the desert source areas around the Arabian Sea region. We did record a clear relationship between the aerosol radiance and synoptic weather patterns with distinct signals over the ocean northwest and southwest of Australia. While the interpretation was limited an aerosol climatology pattern was presented.

  17. Volcanic aerosol layer formed in the tropical upper troposphere by the eruption of Mt. Merapi, Java, in November 2010 observed by the spaceborne lidar CALIOP

    NASA Astrophysics Data System (ADS)

    Shibata, Takashi; Kinoshita, Taro

    2016-02-01

    Mt. Merapi in Java, Indonesia, erupted in November 2010. The eruption was proved to be the source of the aerosol layer observed by a ground-based lidar at Biak, Indonesia, in January 2011 using data on the global distribution of aerosols observed by the spaceborne cloud-aerosol lidar with orthogonal polarization (CALIOP). These data were used to describe how the volcanic aerosols produced by the volcanic eruption diffused throughout the tropical tropopause layer (TTL). The equivalent maximum total amount of volcanic SO2 estimated from the spatially integrated total amount of aerosols was 0.09 Tg, which is one-third to half that of gaseous SO2 after the eruption was observed by the ozone monitoring instrument satellite. The obtained cirrus-cloud-appearance frequency data exhibit a seasonal cycle having its maximum in winter and no detectable variations that are synchronized with the increase in TTL volcanic aerosols.

  18. Sudden changes in aerosol and gas concentrations in the central Arctic marine boundary layer: Causes and consequences

    NASA Astrophysics Data System (ADS)

    Bigg, E. Keith; Leck, Caroline; Nilsson, E. Douglas

    2001-12-01

    Measurements of aerosol number size distributions and concentrations of the precursor gases dimethyl sulfide, sulfur dioxide and ammonia were made within the pack ice region of the central Arctic Ocean during July and August 1996 from the icebreaker Oden. Changes in concentration, sometimes exceeding the entire seasonal variation, often occurred within an hour and attempts to find the reasons for them are described. Vertical profiles of aerosol concentration in Aitken and accumulation mode particles obtained on helicopter flights revealed intense concentration gradients in the lowest 1000 m. Those below 100 m were common. Concentrations of accumulation mode particles were usually greater near the surface than at 100 m. Four representative case studies for which vertical aerosol profiles were obtained are presented. Observations of rapid large changes in near-surface concentration of aerosols in different size ranges are compared with the vertical profiles, meteorological information, and acoustic or optical remote sensing to infer processes causing the changes. Comparison of simultaneous variations in aerosols and precursor gas concentrations are used to define the vertical profiles of the gases. It was found that dimethyl sulfide and ammonia concentrations usually must have been strongly depleted near the surface relative to concentrations at about 100 m. Sulfur dioxide profiles appeared to be more complex. Turbulence or vertical air motions initiated by atmospheric wave motions trapped within the stable boundary layer appeared to be directly responsible for many of the sudden concentration changes, through interaction with concentration gradients close to the surface. The presence of low-level jets also had direct or indirect influences on mixing in the lowest few hundred meters. The extent to which aerosols measured near the surface can determine the microphysics of central Arctic marine boundary layer clouds is examined.

  19. Production Of Titan'S Aerosols Analogues By Radio Frequency Plasma Discharge

    NASA Astrophysics Data System (ADS)

    Szopa, Cyril; Cernogora, G.; Quirico, E.; Bernard, J.; Coll, P.

    2006-09-01

    Titan's organic aerosols play a significant role in the physico-chemical mechanisms of the Titan's atmosphere and heat transfer to the Titan's surface. They also contribute to the physico-chemical properties of the Titan's surface, and more particularly to its reflectance, as they can have accumulated at the surface fro a long period. However, the amount of direct data dealing with the Titan's aerosols is quite low, and the data recovered by the Cassini and Huygens probes remain difficult to interpret without any reference data. This is the reason why we developed a laboratory experiment which simulates the Titan's atmosphere chemistry and produces analogues of Titan's aerosols, with the aim to study the properties of the Titan's aerosols and their way of formation.. In this experiment, the Titan's chemistry is simulated by a low pressure Radio Frequency plasma discharge in a N2-CH4 gas mixture. In this device, aerosols are produced in the gas phase without interaction with the reactor walls. The aim of this paper is to present recent results obtained with this experiment. Chemical composition, physical properties, morphology of the produced particles will be presented, as well as their dependence on the plasma conditions. Moreover, the properties of the plasma characterized by optical and eletrcial diagnostics will also be presented. A correlation of the solids particles properties and the plasma characteristics will be attempted. We will finally attempt to correlate these laboratory results with the known properties of the Titan's aerosols in order to try to bring additional information on the Titan's aerosols properties and their way of formation.

  20. The ASTAR 2007 April 14 haze layer: The radiative effect of an aged and internally mixed aerosol in the Arctic

    NASA Astrophysics Data System (ADS)

    Engvall, A.-C.; Ström, J.; Tunved, P.; Schlager, H.; Minikin, A.

    2009-04-01

    INTRODUCTION The ASTAR project (Arctic Study of Tropospheric Aerosol and Radiation) is aimed at investigating the physico-chemical properties of the Arctic tropospheric aerosol by means of aircraft measurements. The goal of the program is to provide an observational dataset for improving not only the assessment of the direct and indirect effects of aerosols on the Arctic radiative balance, but also the aerosol parameterisation in the regional climate model HIRHAM [Rinke, et al., 1999; Treffeisen, et al., 2005]. The ASTAR 2007 campaign was conducted from March 18 - April 18 in 2007, Svalbard. This timing was chosen to make the measurements span during the Arctic spring due to its frequent Arctic hazes. In the present study we focus on an aerosol layer observed north of Svalbard at an altitude of around 3 km during the campaign. Due to recent discussions about the Arctic temperature amplification and the importance of soot in the atmosphere and its radiative effects, the aim of the present study is to evaluate the potential magnitude of the radiative effects such a haze layer might have in the Arctic. METHODS In the present study we have analysed in-situ observations of aerosol number densities of particles larger than 10 nm and 260 nm in diameter (henceforth denoted N10 and N260, respectively), aerosol size distributions, aerosol light scattering and absorption, and concentrations of carbon monoxide (CO) and ozone (O3). The measurements were conducted from the German DLR Falcon 20 research aeroplane. N10 was measured using a condensation particle counter (CPC) model TSI 3010. The aerosol size distribution between 17 and 239 nm was measured with a Differential Mobility Particle Sizer (DMPS) in stepwise mode utilising 13 bins, each of which was measured during 10 s. The aerosol size distribution between 260 and 2200 nm was observed with an optical particle counter (OPC) GRIMM, model 3.709, which sized the particles in 12 bins at 1 Hz. We also used information about

  1. Development and Applications of a New, High-Resolution, Operational MISR Aerosol Product

    NASA Astrophysics Data System (ADS)

    Garay, M. J.; Diner, D. J.; Kalashnikova, O.

    2014-12-01

    Since early 2000, the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA's Terra satellite has been providing aerosol optical depth (AOD) and particle property retrievals at 17.6 km spatial resolution. Capitalizing on the capabilities provided by multi-angle viewing, the operational MISR algorithm performs well, with about 75% of MISR AOD retrievals falling within 0.05 or 20% × AOD of the paired validation data from the ground-based Aerosol Robotic Network (AERONET), and is able to distinguish aerosol particles by size and sphericity, over both land and water. These attributes enable a variety of applications, including aerosol transport model validation and global air quality assessment. Motivated by the adverse impacts of aerosols on human health at the local level, and taking advantage of computational speed advances that have occurred since the launch of Terra, we have implemented an operational MISR aerosol product with 4.4 km spatial resolution that maintains, and sometimes improves upon, the quality of the 17.6 km resolution product. We will describe the performance of this product relative to the heritage 17.6 km product, the global AERONET validation network, and high spatial density AERONET-DRAGON sites. Other changes that simplify product content, and make working with the data much easier for users, will also be discussed. Examples of how the new product demonstrates finer spatial variability of aerosol fields than previously retrieved, and ways this new dataset can be used for studies of local aerosol effects, will be shown.

  2. Aerosol production by high-velocity molten-metal droplets

    SciTech Connect

    Rader, D J; Benson, D A

    1988-06-01

    This report presents the results of an experimental study of the aerosol produced by high-velocity molten-metal droplets. These tests are intended to simulate the reduction of high-velocity fragments into aerosol in high-explosive detonations or reactor accidents involving nuclear materials. The primary droplets are produced by the heating and electromagnetic launch of metal wires; velocities approaching Mach 1 can be obtained at present. Size distributions obtained tungsten and zirconium droplets burning in air. Lognormal size distributions were observed in both cases with DMPS-equivalent mean diameters of about 0.4 ..mu..m and geometric standard deviations of about two. SEM and TEM analysis of aerosol samples collected by a point-to-plane electrostatic precipitator showed that the majority of these particles were web-like chain agglomerates. Tests performed in argon atmospheres produced several orders-of-magnitude less aerosol mass than in equivalent air tests, supporting the key role combustion plays in secondary aerosol generation. 26 refs., 14 figs., 2 tabs.

  3. Aerosol Production from Charbroiled and Wet-Fried Meats

    NASA Astrophysics Data System (ADS)

    Niedziela, R. F.; Blanc, L. E.

    2012-12-01

    Previous work in our laboratory focused on the chemical and optical characterization of aerosols produced during the dry-frying of different meat samples. This method yielded a complex ensemble of particles composed of water and long-chain fatty acids with the latter dominated by oleic, stearic, and palmitic acids. The present study examines how wet-frying and charbroiling cooking methods affect the physical and chemical properties of their derived aerosols. Samples of ground beef, salmon, chicken, and pork were subject to both cooking methods in the laboratory, with their respective aerosols swept into a laminar flow cell where they were optically analyzed in the mid-infrared and collected through a gas chromatography probe for chemical characterization. This presentation will compare and contrast the nature of the aerosols generated in each cooking method, particularly those produced during charbroiling which exposes the samples, and their drippings, to significantly higher temperatures. Characterization of such cooking-related aerosols is important because of the potential impact of these particles on air quality, particularly in urban areas.

  4. Winter monsoon variation of lower tropospheric aerosol layers at a tropical coastal station, Trivandrum (8°33' N, 77°E), India

    NASA Astrophysics Data System (ADS)

    Satyanarayana, M.; Veerabuthiran, S.; Ramakrishna Rao, D.; Presennakumar, B.; Mohankumar, S. V.; Muraleedharan Nair, S.; Sreeja, R.

    Tropospheric aerosols play an important role in cloud physics and radiative transfer process. They show a high degree of variability in their characteristics both in space and time. The features of the background aerosol at any location or region depend to a large extent on the local source regions and various meteorological parameters at the time of measurement. Apart from the natural sources in and around the observatory station, anthropogenic additions of aerosols also affect the radiation budget and chemical composition. Besides this, it is realized in recent years that aerosols generated at one place could be transported over long distances by the wind systems and produce consequent effects at locations much farther away from the source. Such transported aerosols may settle as stratified layers in the atmosphere typically in the altitude of 1 to 4 km. These aerosol layers will have important effect in the local climate and atmospheric environment because of their role in radiative transfer process and cloud physics. Lidar observations had been conducted to study the long-range transport of aerosol and their effect at tropical station, Trivandrum during the northern winter period of 2002-2004. The presence of aerosol layers was observed on many days below 4 km during the above period. The high extinction coefficient is observed in the layer region and typically it is found to be 3.4 x 10-4 m-1. The aerosol optical depth is calculated by integrating the extinction values in the aerosol layer region and it is found to be between 0.25 and 0.35. The plausible reasons for the formation of these layers were explained using the wind circulation pattern and air back trajectories.

  5. Ozone and aerosol distributions measured by airborne lidar during the 1988 Arctic Boundary Layer Experiment

    NASA Technical Reports Server (NTRS)

    Browell, Edward V.; Butler, Carolyn F.; Kooi, Susan A.

    1991-01-01

    Consideration is given to O3 and aerosol distributions measured from an aircraft using a DIAL system in order to study the sources and sinks of gases and aerosols over the tundra regions of Alaska during summer 1988. The tropospheric O3 budget over the Arctic was found to be strongly influenced by stratospheric intrusions. Regions of low aerosol scattering and enhanced O3 mixing ratios were usually correlated with descending air from the upper troposphere or lower stratosphere.

  6. The study of aerosol and ozone measurements in lower boundary layer with UAV helicopter platform

    NASA Astrophysics Data System (ADS)

    Lin, Po-hsiung; Chen, Wen-nai

    2013-04-01

    This study describes the aerosol and ozone measurement in the lower atmospheric boundary layer of highly polluted region at Kao-hsiung, Taiwan with a small unmanned aerial vehicle (UAV) helicopter platform. This UAV helicopter, modified from Gaui-X7 electronic-power model helicopter with autopilot AHRS (Altitude-Head-Reference System) kit, has fast climb speed up to 700 m height and keeps stable status for atmospheric measurements in five-minute fly leg. Several quick-replaced battery packages are ready on ground for field intensive observation. The payload rack under this UAV helicopter carries a micro-Aethalometer (black carbon concentration), ozone meter, temperature-humidity sensor, barometer and a time-lapse digital camera. The field measurement site closes to Linyuan Petrochemical Industrial Park, where is one of the heavy polluted regions in Taiwan. Balloon-borne Vaisala RS-92 radiosonde and CL31 Lidar Ceilometer are used to provide the background of the atmosphere at the same time. More data analysis measured by UAV helicopter and its potential application will be discussed.

  7. Production of Titan's aerosols analogues by radio frequency plasma discharge

    NASA Astrophysics Data System (ADS)

    Szopa, C.; Cernogora, G.; Boufendi, L.; Cavarroc, M.; Quirico, E.; Bernard, J. M.; Coll, P.; Jolly, A.

    Titan s organic aerosols play a significant role in the physico-chemical mechanisms of the Titan s atmosphere and heat transfer to the Titan s surface They also contribute to the physico-chemical properties of the Titan s surface and more particularly to its reflectance as they can have accumulated at the surface fro a long period However the amount of direct data dealing with the Titan s aerosols is quite low and the data recovered by the Cassini and Huygens probes remain difficult to interpret without any reference data This is the reason why we developed a laboratory experiment which simulates the Titan s atmosphere chemistry and produces analogues of Titan s aerosols with the aim to study the properties of the Titan s aerosols and their way of formation In this experiment the Titan s chemistry is simulated by a low pressure Radio Frequency plasma discharge in a N2-CH4 gas mixture In this device aerosols are produced in the gas phase without interaction with the reactor walls The aim of this paper is to present recent results obtained with this experiment Chemical composition physical properties morphology of the produced particles will be presented as well as their dependence on the plasma conditions Moreover the properties of the plasma characterized by optical and eletrcial diagnostics will also be presented A correlation of the solids particles properties and the plasma characteristics will be attempted We will finally attempt to correlate these laboratory results with the known properties of the Titan s aerosols in order to try to bring

  8. Impact of Stronger Production and Loss Rates of Secondary Organic Aerosols on their Global Distribution and Budget

    NASA Astrophysics Data System (ADS)

    Hodzic, A.; Kasibhatla, P. S.; Cappa, C. D.; Madronich, S.; Jo, D. S.; Park, R.; Jimenez, J. L.

    2015-12-01

    Organic aerosols are observed to be the major constituents of submicron particles worldwide, and yet their atmospheric lifecycle including formation, ageing, and removal processes is poorly understood. Recent laboratory and ambient measurements suggest that both production yields and removal rates of chemically produced secondary organic aerosols (SOA) are much stronger and more diverse than currently assumed in chemistry-climate models (which typically consider wet deposition as the major loss process). In this study, we re-assess the global SOA distribution and budget with newly proposed SOA production and loss processes derived from these recent measurements, as well as from theoretical calculations. We evaluate and discuss the relative importance of removal pathways for organic vapors and particles (e.g. dry and wet deposition, photo-dissociation, evaporation, and heterogeneous surface reactions), and their effect on the SOA vertical distribution and budget using the GEOS-Chem global chemistry-transport model. We compare simulated SOA from various model configurations against ground, aircraft and satellite measurements to assess the extent to which these new developments in our understanding of SOA formation and removal processes are consistent with observed characteristics of the SOA distribution. Our results show strong changes in predicted vertical profiles of organic aerosols with higher SOA concentrations in the boundary layer and lower concentrations in the upper troposphere, which appear to be in a better agreement with aircraft measurements.

  9. Production Mechanism, Number Concentration, Size Distribution, Chemical Composition, and Optical Properties of Sea Spray Aerosols Workshop, Summer 2012

    SciTech Connect

    Meskhidze, Nicholas

    2013-10-21

    The objective of this workshop was to address the most urgent open science questions for improved quantification of sea spray aerosol-radiation-climate interactions. Sea spray emission and its influence on global climate remains one of the most uncertain components of the aerosol-radiation-climate problem, but has received less attention than other aerosol processes (e.g. production of terrestrial secondary organic aerosols). Thus, the special emphasis was placed on the production flux of sea spray aerosol particles, their number concentration and chemical composition and properties.

  10. Integrated Cloud-Aerosol-Radiation Product using CERES, MODIS, CALIPSO and CloudSat Data

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Jensen, J. B.

    2015-12-01

    iant sea-salt aerosol particles (dry radius, rd > 0.5 μm) occur nearly everywhere in the marine boundary layer and frequently above. This study presents observations of atmospheric sea-salt size distributions in the range 0.7 < rd < 14 μm based on external impaction of sea-spray aerosol particles onto microscope polycarbonate microscope slides. The slides have very large sample volumes, typically about 250 L over a 10-second sampling period. This provides unprecedented sampling of giant sea-salt particles for flights in marine boundary layer air. The slides were subsequently analyzed in a humidified chamber using dual optical digital microscopy. At a relative humidity of 90% the sea-salt aerosol particles form spherical cap drops. Based on measurement the volume of the spherical cap drop and assuming NaCl composition, the Kohler equation is used to derive the dry salt mass of tens of thousands of individual aerosol particles on each slide. Size distributions are given with a 0.2 μm resolution. The slides were exposed from the NSF/NCAR C-130 research aircraft during the 2008 VOCALS project off the coast of northern Chile and the 2011 ICE-T in the Caribbean. In each deployment, size distributions using hundreds of slides are used to relate fitted log-normal size distributions parameters to wind speed, altitude and other atmospheric conditions. The size distributions provide a unique observational set for initializing cloud models with coarse-mode aerosol particle observations for marine atmospheres.

  12. The uncertainty of MODIS C6 aerosol optical depth product over land

    NASA Astrophysics Data System (ADS)

    Wu, Yerong; de Graaf, Martin; Menenti, Massimo

    2015-04-01

    Aerosol Optical Depth (AOD) has an important impact on climate change and air quality. A number of AOD satellite data products have been released, like Moderate Resolution Imaging Spectroradiometer (MODIS) AOD product, which are further applied for monitoring PM2.5, for long-term aerosol trend analysis, and for estimating aerosol radiative forcing. However, the accuracy of MODIS AOD product with ±0.03 or 15-20% of global mean value over land is still low for extensive scientific research. To investigate the accuracy of the product, a synthetic experiment was designed where the errors introduced by both radiometry and algorithm, e.g. instrument calibration, gas correction and cloud mask, and some assumptions on aerosol properties can be removed. Through analysis of the mean value of retrieved AOD over 1520 observational configurations, the algorithm performs very well with small errors (up to 0.2%) for most cases, while for some extreme cases (eg., AOD=5.0), it performs less accurately (> 3%). The uncertainty also shows a trend related to the geometry of observations (e.g., scattering angle). The results suggest higher accuracy at large scattering angles, and lower accuracy at small scattering angles. The main reason for the uncertainty is an inappropriate assumption on surface reflectance, where surface reflectance is regarded as a function of aerosol loading and mixing ratio. Therefore, a more accurate representation of the surface reflectance will increase the accuracy of the MODIS AOD product.

  13. Air pollution of Moscow by the carbon monoxide and aerosols, boundary layer parameters and estimation of the CO sources intensity.

    NASA Astrophysics Data System (ADS)

    Rakitin, V.; Fokeeva, E.; Kuznetsov, R.; Emilenko, A.; Kopeikin, V.

    2009-04-01

    The results of measurements of the carbon monoxide total content, the soot and submicron aerosols content are given for the period 2005-2008 over Moscow. Two identical grating spectrometers of medium resolution (0,2sm-1) are used with appropriate solar tracking systems, one of which is located outside the city at Zvenigorod Scientific Station (ZSS 56oN, 38oE, 60km West from Moscow in the rural zone) and the other one is inside a city center. This method makes possible to determine the characteristics of anthropogenic pollution, urban part of the CO content. Some simultaneously measurements of aerosols content, the CO column and CO background concentrations in Moscow, autumn 2007 are presented. Nephelometer and quartz filters for soot sampling were used for aerosols measurements. Correlations coefficients between aerosols, CO background concentration and urban part of the CO content were obtained. Permanent sounding of boundary layer was carried out using acoustic locator (SODAR) LATAN-3. Applications of SODAR data (profile of wind speed and inversion height) makes possible to forecast of air pollution situations in megacities area. We obtained the correlation coefficients for the urban part of the CO content with the wind speed for cold and warm seasons. Analysis results of measurements demonstrated preeminent influence of the wind in certain boundary layer (up to 500m) upon the CO extension. The intensity of CO sources in Moscow was estimated. The systematization of CO diurnal variations for different meteorological conditions was performed. Comparing our results with the results of the earlier measurements period (1993-2005), we found out that the urban part of the CO content in the surface air layer over the city did not increase in spite of more than tripled number of motor-vehicles in Moscow. So using the applications of this spectroscopic method we can obtain the air pollution trend from the averaged air pollution measured values.

  14. Chemical relations between atmospheric aerosols, deposition and stone decay layers on historic buildings at the mediterranean coast

    NASA Astrophysics Data System (ADS)

    Torfs, K.; Van Grieken, R.

    To evaluate the effects of the environment on weathering of historical buildings in the Mediterranean Basin, an elaborate study has been carried out at four monuments, with specific interest directed on the action of air pollution and marine salts. The composition of the atmosphere around the monuments has been investigated by monitoring the aerosols and the total deposition. These results are combined with the stone decay phenomena to interpret the deterioration at the respective monuments. In Eleusis, Greece, a highly industrialized area, high concentrations of heavy metals and sulphate are found in the aerosols and deposition and in the decay layers of the stone, while the marine influence is obscured, in spite of its location close to the sea. In Malta and in Cadiz (Spain), the influence of the sea dominates in the stone weathering process. In Bari (Italy), next to the effects of marine aerosols on the stone decay inside and outside the building, high concentrations of sulphate are observed on the outside stones. The aerosols and depositions reflect a relatively small influence of anthropogenic derived elements; this points out the action of gaseous SO 2 on the stones.

  15. Process Conditions of Forming the Surface Layer of Aluminum Powder Product by Layer-by-layer Laser Sintering

    NASA Astrophysics Data System (ADS)

    Saprykina, N. A.; Saprykin, A. A.; Ibragimov, E. A.; Arkhipova, D. A.

    2016-07-01

    The paper presents data on state of the art in selective laser sintering of products. Layer-by-layer sintering is shown to be a future-oriented technology, making it possible to synthesize products of metal powder materials. Factors, influencing the quality of a sintered product, are revealed in the paper. It presents outcomes of experiments, focused on the dependence of surface layer thickness of sintered aluminum powder PA-4 on laser processing conditions. Basic factors, influencing the quality of a sintered surface layer include laser power, speeds of scanning and moving the laser beam on the layer of powder. Thickness of the sintered layer varies from 0.74 to 1.55 mm, as the result of changing the laser processing conditions.

  16. Rethinking the global secondary organic aerosol (SOA) budget: stronger production, faster removal, shorter lifetime

    NASA Astrophysics Data System (ADS)

    Hodzic, Alma; Kasibhatla, Prasad S.; Jo, Duseong S.; Cappa, Christopher D.; Jimenez, Jose L.; Madronich, Sasha; Park, Rokjin J.

    2016-06-01

    Recent laboratory studies suggest that secondary organic aerosol (SOA) formation rates are higher than assumed in current models. There is also evidence that SOA removal by dry and wet deposition occurs more efficiently than some current models suggest and that photolysis and heterogeneous oxidation may be important (but currently ignored) SOA sinks. Here, we have updated the global GEOS-Chem model to include this new information on formation (i.e., wall-corrected yields and emissions of semi-volatile and intermediate volatility organic compounds) and on removal processes (photolysis and heterogeneous oxidation). We compare simulated SOA from various model configurations against ground, aircraft and satellite measurements to assess the extent to which these improved representations of SOA formation and removal processes are consistent with observed characteristics of the SOA distribution. The updated model presents a more dynamic picture of the life cycle of atmospheric SOA, with production rates 3.9 times higher and sinks a factor of 3.6 more efficient than in the base model. In particular, the updated model predicts larger SOA concentrations in the boundary layer and lower concentrations in the upper troposphere, leading to better agreement with surface and aircraft measurements of organic aerosol compared to the base model. Our analysis thus suggests that the long-standing discrepancy in model predictions of the vertical SOA distribution can now be resolved, at least in part, by a stronger source and stronger sinks leading to a shorter lifetime. The predicted global SOA burden in the updated model is 0.88 Tg and the corresponding direct radiative effect at top of the atmosphere is -0.33 W m-2, which is comparable to recent model estimates constrained by observations. The updated model predicts a population-weighed global mean surface SOA concentration that is a factor of 2 higher than in the base model, suggesting the need for a reanalysis of the contribution of

  17. Aerosol Lidar and MODIS Satellite Comparisons for Future Aerosol Loading Forecast

    NASA Technical Reports Server (NTRS)

    DeYoung, Russell; Szykman, James; Severance, Kurt; Chu, D. Allen; Rosen, Rebecca; Al-Saadi, Jassim

    2006-01-01

    Knowledge of the concentration and distribution of atmospheric aerosols using both airborne lidar and satellite instruments is a field of active research. An aircraft based aerosol lidar has been used to study the distribution of atmospheric aerosols in the California Central Valley and eastern US coast. Concurrently, satellite aerosol retrievals, from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard the Terra and Aqua satellites, were take over the Central Valley. The MODIS Level 2 aerosol data product provides retrieved ambient aerosol optical properties (e.g., optical depth (AOD) and size distribution) globally over ocean and land at a spatial resolution of 10 km. The Central Valley topography was overlaid with MODIS AOD (5x5 sq km resolution) and the aerosol scattering vertical profiles from a lidar flight. Backward air parcel trajectories for the lidar data show that air from the Pacific and northern part of the Central Valley converge confining the aerosols to the lower valley region and below the mixed layer. Below an altitude of 1 km, the lidar aerosol and MODIS AOD exhibit good agreement. Both data sets indicate a high presence of aerosols near Bakersfield and the Tehachapi Mountains. These and other results to be presented indicate that the majority of the aerosols are below the mixed layer such that the MODIS AOD should correspond well with surface measurements. Lidar measurements will help interpret satellite AOD retrievals so that one day they can be used on a routine basis for prediction of boundary layer aerosol pollution events.

  18. Particle Property Data Quality Flags for the MISR Aerosol Product

    NASA Astrophysics Data System (ADS)

    Gaitley, B. J.; Kahn, R. A.; Garay, M. J.

    2012-12-01

    The MISR instrument aboard the NASA Earth Observing System's Terra satellite has the unique capability to retrieve aerosol properties under favorable conditions. General aerosol type retrieval quality guidelines are provided in the MISR Data Quality Statement and related publications. Here we report on the steps we are taking to provide an aerosol-type data quality flag, to be provided with each individual retrieval result. Some factors affecting retrieval quality that can be assessed pre-retrieval are the number of cameras available, the range of scattering angles and surface conditions such as shallow water or seasonal coastal runoff. Factors that must be assessed post-retrieval include low values of retrieved optical depth and the number and type of mixtures successfully passing the MISR algorithm acceptance criteria. Regional monthly plots with MISR measurements binned at 0.5 degree resolution with color-coded stratification of one or more parameters is the main method for identifying locations and times where particle properties are retrieved. Individual MISR values such as mid-visible AOD, number and type of mixtures passing, number of cameras used, the range and maximum scattering angles are plotted individually or as joint distributions. Initially, thresholds and conditions are determined for each MISR parameter separately. Finally, MISR parameters are combined for a given month and region, with their thresholds, to show the overall quality of the retrieval for determining particle properties. Multi-month summaries for more than twelve years of MISR data will aid in assessing quality. Seasons and regions that regularly show poorly constrained aerosol type results are identified, as are times and places where particle property information can be used with confidence. This work is performed in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration and in part at the NASA

  19. Aerosol Products from The Future Space Lidar AEOLUS

    NASA Astrophysics Data System (ADS)

    Martinet, Pauline; Dabas, Alain; Lever, Vincent; Flamant, Pierre; Huber, Dorit

    2016-06-01

    Ready for launch by the end of 2016, the Doppler lidar mission AEOLUS from the European Space Agency (ESA) will be the first High-Spectral Resolution Lidar (HSRL) in space. Operating in the UV, it implements two detection channels for aerosol and molecular backscatter. The system is primarily designed for the measurement of winds, but the HSRL capability enables the measurement of the particulate backscatter and extinction coefficients without any a priori assumption on the aerosol type. The level-2A (L2A) processor has been developed for these measurements and tested with synthetic data. The results show good aerosol backscatter profiles can be retrieved. Extinction coefficients are reasonable but do not reach the quality of backscatter coefficients. A precise, full, radiometric calibration of the lidar is required. A major limitation of the system is a single polarization component of the light is detected leading to an underestimation of backscatter coefficients when the atmospheric particles are depolarizing. The vertical resolution goes from 250 meters in the lowest part of the atmosphere, to 2 km in the lower stratosphere. The maximum altitude can reach above 20km. The basic horizontal averaging is 90km. Averaging on shorter distances (down to a few km) are possible but require a sufficient signal to noise ratio.

  20. ALTERNATIVE FORMULATIONS TO REDUCE CFC USE IN U.S. EXEMPTED AND EXCLUDED AEROSOL PRODUCTS

    EPA Science Inventory

    The report examines products exempted and excluded from those affected by the 1978 ban on the use of chlorofluorocarbons (CFCs) as aerosol propellants, the present consumption of CFCs still utilized for these products in the U.S., and alternative formulations which may be used to...

  1. Analysis of reversibility and reaction products of glyoxal uptake onto ammonium sulfate aerosol

    NASA Astrophysics Data System (ADS)

    Galloway, M. M.; Chhabra, P. S.; Chan, A. W.; Surratt, J. D.; Kwan, A. J.; Wennberg, P. O.; Flagan, R. C.; Seinfeld, J. H.; Keutsch, F. N.

    2009-04-01

    Glyoxal, the smallest alpha-dicarbonyl, is an oxidation product of both biogenic and anthropogenic volatile organic compounds (Fu et al. JGR 113, D15303, 2008). Despite its low molecular weight, its role in secondary organic aerosol (SOA) formation has gained interest and a recent study suggested that it accounts for more than 15% of SOA in Mexico City (Volkamer et al. GRL 34, L19807, 2007). Despite numerous previous studies, questions remain regarding the processes controlling glyoxal uptake onto aerosol, including the role of acid catalysis, degree of reversibility, and identity of aerosol phase reaction products. We present results of chamber aerosol studies (Galloway et al. ACPD 8, 20799, 2008) and laboratory studies of bulk samples aimed at improving the understanding of these processes, in particular formation of oligomers and organosulfates of glyoxal, as well as the formation of imidazoles (carbon-nitrogen containing heterocyclic aromatic compounds) under dark and irradiated conditions. The relevance of these classes of reaction products extends beyond glyoxal, as evidence of oligomers and organosulfates other than those of glyoxal have been found in ambient aerosol (Surratt et al. JPCA 112, 8345, 2008; Denkenberger et al. Environ. Sci. Technol. 41, 5439, 2007). Experiments in which a chamber air mass was diluted after equilibration of glyoxal uptake onto ammonium sulfate seed aerosol (relative humidity 60% and glyoxal mixing ratios of 25-200 ppbv) shows that under these conditions uptake is reversible. The most important condensed phase products are hydrated oligomers of glyoxal, which are also formed reversibly under these conditions. Our studies show that organosulfates were not formed under dark conditions for neutral or acidified aerosol; similarly, Minerath et al. have recently shown that formation of a different class of organosulfates (alkyl sulfates) also proceeds very slowly even under acidic conditions (Environ. Sci. Technol. 42, 4410, 2008). The

  2. Measuring the characteristics of stratospheric aerosol layer and total ozone concentration at Siberian Lidar Station in Tomsk

    NASA Astrophysics Data System (ADS)

    Nevzorov, Aleksey; Bazhenov, Oleg; Burlakov, Vladimir; Dolgii, Sergey

    2015-11-01

    We consider the results of long-term remote optical monitoring, obtained at the Siberian Lidar Station of Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences in Tomsk (56.5 °N, 85.0 °E). The scattering characteristics of stratospheric aerosol layer, obtained according to data of lidar measurements since 1986, are presented. We analyze the trends of changes in the total ozone (TO) content over Tomsk for the period 1996-2013 according to data of spectrophotometric measurements with employment of TOMS satellite data for the period 1979- 1994. We determined the periods of elevated content of stratospheric aerosol over Tomsk after a series of explosive eruptions of volcanoes of Pacific Ring of Fire and Iceland in 2006-2011. Since the second half of 1990s, researchers record an increasing TO trend, equaling 0.65 DU/yr for the period 1996-2013.

  3. Certain Results of Measurements of Characteristics of Stratospheric Aerosol Layer and Total Ozone Content at Siberian Lidar Station in Tomsk

    NASA Astrophysics Data System (ADS)

    Nevzorov, Aleksey; Bazhenov, Oleg; Burlakov, Vladimir; Dolgii, Sergey

    2016-06-01

    We consider the results of long-term remote optical monitoring, obtained at the Siberian Lidar Station of Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences in Tomsk (56.5°N, 85.0°E). The scattering characteristics of stratospheric aerosol layer, obtained according to data of lidar measurements since 1986, are presented. We analyze the trends of changes in the total ozone (TO) content over Tomsk for the period 1996-2013 according to data of spectrophotometric measurements with employment of Total Ozone Mapping Spectrometer (TOMS) data for the period 1979-1994. We determined the periods of elevated content of stratospheric aerosol over Tomsk aftera series of explosive eruptions of volcanoes of Pacific Ring of Fire and Iceland in 2006-2011. Since the second half of 1990s, we record an increasing TO trend, equaling 0.65 DU/yr for the period 1996-2013.

  4. Forecasting Plant Productivity and Health Using Diffuse-to-Global Irradiance Ratios Extracted from the OMI Aerosol Product

    NASA Technical Reports Server (NTRS)

    Knowlton, Kelly; Andrews, Jane C.; Ryan, Robert E.

    2007-01-01

    Atmospheric aerosols are a major contributor to diffuse irradiance. This Candidate Solution suggests using the OMI (Ozone Monitoring Instrument) aerosol product as input into a radiative transfer model, which would calculate the ratio of diffuse to global irradiance at the Earth s surface. This ratio can significantly influence the rate of photosynthesis in plants; increasing the ratio of diffuse to global irradiance can accelerate photosynthesis, resulting in greater plant productivity. Accurate values of this ratio could be useful in predicting crop productivity, thereby improving forecasts of regional food resources. However, disagreements exist between diffuse-to-global irradiance values measured by different satellites and ground sensors. OMI, with its unique combination of spectral bands, high resolution, and daily global coverage, may be able to provide more accurate aerosol measurements than other comparable sensors.

  5. An Accuracy Assessment of the CALIOP/CALIPSO Version 2/Version 3 Daytime Aerosol Extinction Product Based on a Detailed Multi-Sensor, Multi-Platform Case Study

    NASA Technical Reports Server (NTRS)

    Kacenelenbogen, M.; Vaughan, M. A.; Redemann, J.; Hoff, R. M.; Rogers, R. R.; Ferrare, R. A.; Russell, P. B.; Hostetler, C. A.; Hair, J. W.; Holben, B. N.

    2011-01-01

    The Cloud Aerosol LIdar with Orthogonal Polarization (CALIOP), on board the CALIPSO platform, has measured profiles of total attenuated backscatter coefficient (level 1 products) since June 2006. CALIOP s level 2 products, such as the aerosol backscatter and extinction coefficient profiles, are retrieved using a complex succession of automated algorithms. The goal of this study is to help identify potential shortcomings in the CALIOP version 2 level 2 aerosol extinction product and to illustrate some of the motivation for the changes that have been introduced in the next version of CALIOP data (version 3, released in June 2010). To help illustrate the potential factors contributing to the uncertainty of the CALIOP aerosol extinction retrieval, we focus on a one-day, multi-instrument, multiplatform comparison study during the CALIPSO and Twilight Zone (CATZ) validation campaign on 4 August 2007. On that day, we observe a consistency in the Aerosol Optical Depth (AOD) values recorded by four different instruments (i.e. spaceborne MODerate Imaging Spectroradiometer, MODIS: 0.67 and POLarization and Directionality of Earth s Reflectances, POLDER: 0.58, airborne High Spectral Resolution Lidar, HSRL: 0.52 and ground-based AErosol RObotic NETwork, AERONET: 0.48 to 0.73) while CALIOP AOD is a factor of two lower (0.32 at 532 nm). This case study illustrates the following potential sources of uncertainty in the CALIOP AOD: (i) CALIOP s low signal-to-noise ratio (SNR) leading to the misclassification and/or lack of aerosol layer identification, especially close to the Earth s surface; (ii) the cloud contamination of CALIOP version 2 aerosol backscatter and extinction profiles; (iii) potentially erroneous assumptions of the aerosol extinction-to-backscatter ratio (Sa) used in CALIOP s extinction retrievals; and (iv) calibration coefficient biases in the CALIOP daytime attenuated backscatter coefficient profiles. The use of version 3 CALIOP extinction retrieval for our case

  6. Global and regional modeling of clouds and aerosols in the marine boundary layer during VOCALS: the VOCA intercomparison

    DOE PAGES

    Wyant, M. C.; Bretherton, Christopher S.; Wood, Robert; Carmichael, Gregory; Clarke, A. D.; Fast, Jerome D.; George, R.; Gustafson, William I.; Hannay, Cecile; Lauer, Axel; et al

    2015-01-09

    A diverse collection of models are used to simulate the marine boundary layer in the southeast Pacific region during the period of the October–November 2008 VOCALS REx (VAMOS Ocean Cloud Atmosphere Land Study Regional Experiment) field campaign. Regional models simulate the period continuously in boundary-forced free-running mode, while global forecast models and GCMs (general circulation models) are run in forecast mode. The models are compared to extensive observations along a line at 20° S extending westward from the South American coast. Most of the models simulate cloud and aerosol characteristics and gradients across the region that are recognizably similar tomore » observations, despite the complex interaction of processes involved in the problem, many of which are parameterized or poorly resolved. Some models simulate the regional low cloud cover well, though many models underestimate MBL (marine boundary layer) depth near the coast. Most models qualitatively simulate the observed offshore gradients of SO2, sulfate aerosol, CCN (cloud condensation nuclei) concentration in the MBL as well as differences in concentration between the MBL and the free troposphere. Most models also qualitatively capture the decrease in cloud droplet number away from the coast. However, there are large quantitative intermodel differences in both means and gradients of these quantities. Many models are able to represent episodic offshore increases in cloud droplet number and aerosol concentrations associated with periods of offshore flow. Most models underestimate CCN (at 0.1% supersaturation) in the MBL and free troposphere. The GCMs also have difficulty simulating coastal gradients in CCN and cloud droplet number concentration near the coast. The overall performance of the models demonstrates their potential utility in simulating aerosol–cloud interactions in the MBL, though quantitative estimation of aerosol–cloud interactions and aerosol indirect effects of MBL clouds

  7. Global and regional modeling of clouds and aerosols in the marine boundary layer during VOCALS: the VOCA intercomparison

    SciTech Connect

    Wyant, M. C.; Bretherton, Christopher S.; Wood, Robert; Carmichael, Gregory; Clarke, A. D.; Fast, Jerome D.; George, R.; Gustafson, William I.; Hannay, Cecile; Lauer, Axel; Lin, Yanluan; Morcrette, J. -J.; Mulcahay, Jane; Saide, Pablo; Spak, S. N.; Yang, Qing

    2015-01-09

    A diverse collection of models are used to simulate the marine boundary layer in the southeast Pacific region during the period of the October–November 2008 VOCALS REx (VAMOS Ocean Cloud Atmosphere Land Study Regional Experiment) field campaign. Regional models simulate the period continuously in boundary-forced free-running mode, while global forecast models and GCMs (general circulation models) are run in forecast mode. The models are compared to extensive observations along a line at 20° S extending westward from the South American coast. Most of the models simulate cloud and aerosol characteristics and gradients across the region that are recognizably similar to observations, despite the complex interaction of processes involved in the problem, many of which are parameterized or poorly resolved. Some models simulate the regional low cloud cover well, though many models underestimate MBL (marine boundary layer) depth near the coast. Most models qualitatively simulate the observed offshore gradients of SO2, sulfate aerosol, CCN (cloud condensation nuclei) concentration in the MBL as well as differences in concentration between the MBL and the free troposphere. Most models also qualitatively capture the decrease in cloud droplet number away from the coast. However, there are large quantitative intermodel differences in both means and gradients of these quantities. Many models are able to represent episodic offshore increases in cloud droplet number and aerosol concentrations associated with periods of offshore flow. Most models underestimate CCN (at 0.1% supersaturation) in the MBL and free troposphere. The GCMs also have difficulty simulating coastal gradients in CCN and cloud droplet number concentration near the coast. The overall performance of the models demonstrates their potential utility in simulating aerosol–cloud interactions in the MBL, though quantitative estimation of aerosol–cloud interactions and aerosol indirect effects of MBL

  8. Near-Cloud Aerosol Properties from the 1 Km Resolution MODIS Ocean Product

    NASA Technical Reports Server (NTRS)

    Varnai, Tamas; Marshak, Alexander

    2014-01-01

    This study examines aerosol properties in the vicinity of clouds by analyzing high-resolution atmospheric correction parameters provided in the MODIS (Moderate Resolution Imaging Spectroradiometer) ocean color product. The study analyzes data from a 2 week long period of September in 10 years, covering a large area in the northeast Atlantic Ocean. The results indicate that on the one hand, the Quality Assessment (QA) flags of the ocean color product successfully eliminate cloud-related uncertainties in ocean parameters such as chlorophyll content, but on the other hand, using the flags introduces a sampling bias in atmospheric products such as aerosol optical thickness (AOT) and Angstrom exponent. Therefore, researchers need to select QA flags by balancing the risks of increased retrieval uncertainties and sampling biases. Using an optimal set of QA flags, the results reveal substantial increases in optical thickness near clouds-on average the increase is 50% for the roughly half of pixels within 5 km from clouds and is accompanied by a roughly matching increase in particle size. Theoretical simulations show that the 50% increase in 550nm AOT changes instantaneous direct aerosol radiative forcing by up to 8W/m2 and that the radiative impact is significantly larger if observed near-cloud changes are attributed to aerosol particles as opposed to undetected cloud particles. These results underline that accounting for near-cloud areas and understanding the causes of near-cloud particle changes are critical for accurate calculations of direct aerosol radiative forcing.

  9. Contribution of airborne microbes to bacterial production and N2 fixation in seawater upon aerosol deposition

    NASA Astrophysics Data System (ADS)

    Rahav, Eyal; Ovadia, Galit; Paytan, Adina; Herut, Barak

    2016-01-01

    Aerosol deposition may supply a high diversity of airborne microbes, which can affect surface microbial composition and biological production. This study reports a diverse microbial community associated with dust and other aerosol particles, which differed significantly according to their geographical air mass origin. Microcosm bioassay experiments, in which aerosols were added to sterile (0.2 µm filtered and autoclaved) SE Mediterranean Sea (SEMS) water, were performed to assess the potential impact of airborne bacteria on bacterial abundance, production, and N2 fixation. Significant increase was observed in all parameters within a few hours, and calculations suggest that airborne microbes can account for one third in bacterial abundance and 50-100% in bacterial production and N2-fixation rates following dust/aerosol amendments in the surface SEMS. We show that dust/aerosol deposition can be a potential source of a wide array of microorganisms, which may impact microbial composition and food web dynamics in oligotrophic marine systems such as the SEMS.

  10. Laser Remote Sensing from ISS: CATS Cloud and Aerosol Level 2 Data Products (Heritage Edition)

    NASA Astrophysics Data System (ADS)

    Rodier, Sharon; Palm, Steve; Vaughan, Mark; Yorks, John; McGill, Matt; Jensen, Mike; Murray, Tim; Trepte, Chip

    2016-06-01

    With the recent launch of the Cloud-Aerosol Transport System (CATS) we have the opportunity to acquire a continuous record of space based lidar measurements spanning from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) era to the start of the EarthCARE mission. Utilizing existing well-validated science algorithms from the CALIPSO mission, we will ingest the CATS data stream and deliver high-quality lidar data sets to the user community at the earliest possible opportunity. In this paper we present an overview of procedures necessary to generate CALIPSO-like lidar level 2 data products from the CATS level 1 data products.

  11. [A simple testing installation for the production of aerosols with constant bacteria-contaminated concentrations].

    PubMed

    Herbst, M; Lehmhus, H; Oldenburg, B; Orlowski, C; Ohgke, H

    1983-04-01

    A simple experimental set for the production and investigation of bacterially contaminated solid-state aerosols with constant concentration is described. The experimental set consists mainly of a fluidized bed-particle generator within a modified chamber for formaldehyde desinfection. The special conditions for the production of a defined concentration of particles and microorganisms are to be found out empirically. In a first application aerosol-sizing of an Andersen sampler is investigated. The findings of Andersen (1) are confirmed with respect to our experimental conditions.

  12. Emissions and Secondary Organic Aerosol Production from Semivolatile and Intermediate Volatility Organic Compounds

    NASA Astrophysics Data System (ADS)

    Robinson, A. L.; Presto, A. A.; Miracolo, M. A.; Donahue, N. M.; Kroll, J. H.; Worsnop, D. R.

    2008-12-01

    Organic aerosols are a highly-dynamic system dominated by both variable gas-particle partitioning and chemical evolution. Important classes of organics include semivolatile and intermediate volatility organic compounds (SVOC and IVOC, respectively). SVOCs are compounds that exist in both the gas and particle phases at typical atmospheric conditions while IVOC are low-volatility vapors that exist exclusively in the gas phase. Both classes have saturation concentrations that are orders of magnitude lower than volatile organic compounds (VOC) that are the traditional subjects of atmosphere chemistry, such as monoterpenes, alkyl benzenes, etc. The SVOC and IVOC are poorly represented for in current atmospheric chemistry models. Source testing indicates that SVOC and IVOC emissions from biomass combustion, diesel engines and other sources exceed the primary organic aerosol emissions; thus the oxidation of these vapors could serve as a significant source of organic aerosol in the atmosphere. The formation of secondary organic aerosol (SOA) from the reactions between OH radicals and SVOCs and IVOCs was investigated in the Carnegie Mellon University smog chamber. Experiments were conducted with n-alkanes and emission surrogates (diesel fuel and lubricating oil). SVOC oxidation produces oxidized organic aerosol but little new organic aerosol mass. This behavior can be explained by the coupled effects of partitioning and aging. Oxidation of SVOC vapors creates low volatility species that partition into the condensed phase; this oxidation also reduces the SVOC vapor concentration which, in turn, requires particle-phase SVOC to evaporate to maintain phase equilibrium. In contrast, oxidation of IVOC results in sustained production of SOA consistent with a reaction with relatively slow kinetics and high mass yield. Aerosol Mass Spectrometer data indicates that the SOA formed from IVOC has a mass spectrum that is quite similar to the oxygenated organic aerosol factor observed in

  13. Enhanced air pollution via aerosol-boundary layer feedback in China

    PubMed Central

    Petäjä, T.; Järvi, L.; Kerminen, V.-M.; Ding, A.J.; Sun, J.N.; Nie, W.; Kujansuu, J.; Virkkula, A.; Yang, X.; Fu, C.B.; Zilitinkevich, S.; Kulmala, M.

    2016-01-01

    Severe air pollution episodes have been frequent in China during the recent years. While high emissions are the primary reason for increasing pollutant concentrations, the ultimate cause for the most severe pollution episodes has remained unclear. Here we show that a high concentration of particulate matter (PM) will enhance the stability of an urban boundary layer, which in turn decreases the boundary layer height and consequently cause further increases in PM concentrations. We estimate the strength of this positive feedback mechanism by combining a new theoretical framework with ambient observations. We show that the feedback remains moderate at fine PM concentrations lower than about 200 μg m−3, but that it becomes increasingly effective at higher PM loadings resulting from the combined effect of high surface PM emissions and massive secondary PM production within the boundary layer. Our analysis explains why air pollution episodes are particularly serious and severe in megacities and during the days when synoptic weather conditions stay constant. PMID:26753788

  14. Uncertainty Analysis And Synergy Of Aerosol Products From Multiple Satellite Sensors For Advanced Atmospheric Research

    NASA Astrophysics Data System (ADS)

    Ichoku, C. M.; Petrenko, M.

    2013-05-01

    Aerosols are tiny particles suspended in the air, and can be made up of wind-blown dust, smoke from fires, and particulate emissions from automobiles, industries, and other natural and man-made sources. Aerosols can have significant impacts on the air quality, and can interact with clouds and solar radiation in such a way as to affect the water cycle and climate. However, the extent and scale of these impacts are still poorly understood, and this represents one of the greatest uncertainties in climate research to date. To fill this gap in our knowledge, the global and local properties of atmospheric aerosols are being extensively observed and measured, especially during the last decade, using both satellite and ground-based instruments, including such spaceborne sensors as MODIS on the Terra and Aqua satellites, MISR on Terra, OMI on Aura, POLDER on PARASOL, CALIOP on CALIPSO, SeaWiFS on SeaStar, and the ground-based Aerosol Robotic Network (AERONET) of sunphotometers. The aerosol measurements collected by these instruments over the last decade contribute to an unprecedented availability of the most complete set of complimentary aerosol measurements ever acquired. Still, to be able to utilize these measurements synergistically, they have to be carefully and uniformly analyzed and inter-compared, in order to understand the uncertainties and limitations of the products - a process that is greatly complicated by the diversity of differences that exist among them. In this presentation, we will show results of a coherent comparative uncertainty analysis of aerosol measurements from the above-named satellite sensors relative to AERONET. We use these results to demonstrate how these sensors perform in different parts of the world over different landcover types as well as their performance relative to one another, thereby facilitating product selection and integration for specific research and applications needs.

  15. Scattering and absorption properties of near-surface aerosol over Gangetic-Himalayan region: the role of boundary-layer dynamics and long-range transport

    NASA Astrophysics Data System (ADS)

    Dumka, U. C.; Kaskaoutis, D. G.; Srivastava, M. K.; Devara, P. C. S.

    2015-02-01

    Light scattering and absorption properties of atmospheric aerosols are of vital importance for evaluating their types, sources and radiative forcing. This is of particular interest over the Gangetic-Himalayan (GH) region due to uplift of aerosol from the plains to the Himalayan range, causing serious effects on atmospheric heating, glaciology and monsoon circulation. In this respect, the Ganges Valley Aerosol Experiment (GVAX) was initiated in Nainital from June 2011 to March 2012 with the aim of examining the aerosol properties, source regions, uplift mechanisms and aerosol-radiation-cloud interactions. The present study examines the temporal (diurnal, monthly, seasonal) evolution of scattering (σlayer dynamics (BLD) and long-range transport (LRT) in aerosol evolution via the Atmospheric Radiation Measurement Mobile Facility. The analysis is separated for particles <10 μm and <1 μm in diameter in order to examine the influence of particle size on optical properties. The σsp and σap exhibit a pronounced seasonal variation between the monsoon low and post-monsoon (November) high, while the scattering wavelength exponent exhibits higher values during the monsoon, in contrast to the absorption Ångström exponent which maximizes in December-March. The elevated-background measuring site provides the advantage of examining the LRT of natural and anthropogenic aerosols from the IGP and southwest Asia and the role of BLD in the aerosol lifting processes. The results reveal higher aerosol concentrations at noontime along with an increase in mixing height, suggesting influence from IGP. The locally emitted aerosols present higher wavelength dependence of the absorption in October-March compared to the rather well-mixed and aged transported aerosols. Monsoon rainfall and seasonally changing air masses contribute to the alteration of the

  16. 21 CFR 700.14 - Use of vinyl chloride as an ingredient, including propellant of cosmetic aerosol products.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... propellant of cosmetic aerosol products. 700.14 Section 700.14 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.14 Use of vinyl chloride as an ingredient, including propellant of cosmetic aerosol...

  17. 21 CFR 700.14 - Use of vinyl chloride as an ingredient, including propellant of cosmetic aerosol products.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... propellant of cosmetic aerosol products. 700.14 Section 700.14 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.14 Use of vinyl chloride as an ingredient, including propellant of cosmetic aerosol...

  18. 21 CFR 700.14 - Use of vinyl chloride as an ingredient, including propellant of cosmetic aerosol products.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... propellant of cosmetic aerosol products. 700.14 Section 700.14 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.14 Use of vinyl chloride as an ingredient, including propellant of cosmetic aerosol...

  19. 21 CFR 700.14 - Use of vinyl chloride as an ingredient, including propellant of cosmetic aerosol products.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... propellant of cosmetic aerosol products. 700.14 Section 700.14 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.14 Use of vinyl chloride as an ingredient, including propellant of cosmetic aerosol...

  20. 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

  1. Experimental Protocol to Investigate Particle Aerosolization of a Product Under Abrasion and Under Environmental Weathering.

    PubMed

    Shandilya, Neeraj; Le Bihan, Olivier Louis; Bressot, Christophe; Morgeneyer, Martin

    2016-01-01

    The present article presents an experimental protocol to investigate particle aerosolization of a product under abrasion and under environmental weathering, which is a fundamental element to the approach of nanosafety-by-design of nanostructured products for their durable development. This approach is basically a preemptive one in which the focus is put on minimizing the emission of engineered nanomaterials' aerosols during the usage phase of the product's life cycle. This can be attained by altering its material properties during its design phase without compromising with any of its added benefits. In this article, an experimental protocol is presented to investigate the nanosafety-by-design of three commercial nanostructured products with respect to their mechanical solicitation and environmental weathering. The means chosen for applying the mechanical solicitation is an abrasion process and for the environmental weathering, it is an accelerated UV exposure in the presence of humidity and heat. The eventual emission of engineered nanomaterials is studied in terms of their number concentration, size distribution, morphology and chemical composition. The purpose of the protocol is to study the emission for test samples and experimental conditions which are corresponding to real life situations. It was found that the application of the mechanical stresses alone emits the engineered nanomaterials' aerosols in which the engineered nanomaterial is always embedded inside the product matrix, thus, a representative product element. In such a case, the emitted aerosols comprise of both nanoparticles as well as microparticles. But if the mechanical stresses are coupled with the environmental weathering, the experimental protocol reveals then the eventual deterioration of the product, after a certain weathering duration, may lead to the emission of the free engineered nanomaterial aerosols too. PMID:27684430

  2. Experimental Protocol to Investigate Particle Aerosolization of a Product Under Abrasion and Under Environmental Weathering.

    PubMed

    Shandilya, Neeraj; Le Bihan, Olivier Louis; Bressot, Christophe; Morgeneyer, Martin

    2016-09-16

    The present article presents an experimental protocol to investigate particle aerosolization of a product under abrasion and under environmental weathering, which is a fundamental element to the approach of nanosafety-by-design of nanostructured products for their durable development. This approach is basically a preemptive one in which the focus is put on minimizing the emission of engineered nanomaterials' aerosols during the usage phase of the product's life cycle. This can be attained by altering its material properties during its design phase without compromising with any of its added benefits. In this article, an experimental protocol is presented to investigate the nanosafety-by-design of three commercial nanostructured products with respect to their mechanical solicitation and environmental weathering. The means chosen for applying the mechanical solicitation is an abrasion process and for the environmental weathering, it is an accelerated UV exposure in the presence of humidity and heat. The eventual emission of engineered nanomaterials is studied in terms of their number concentration, size distribution, morphology and chemical composition. The purpose of the protocol is to study the emission for test samples and experimental conditions which are corresponding to real life situations. It was found that the application of the mechanical stresses alone emits the engineered nanomaterials' aerosols in which the engineered nanomaterial is always embedded inside the product matrix, thus, a representative product element. In such a case, the emitted aerosols comprise of both nanoparticles as well as microparticles. But if the mechanical stresses are coupled with the environmental weathering, the experimental protocol reveals then the eventual deterioration of the product, after a certain weathering duration, may lead to the emission of the free engineered nanomaterial aerosols too.

  3. Modifications of the quasi-biennial oscillation by a geoengineering perturbation of the stratospheric aerosol layer

    NASA Astrophysics Data System (ADS)

    Aquila, V.; Garfinkel, C. I.; Newman, P. A.; Oman, L. D.; Waugh, D. W.

    2014-03-01

    This paper examines the impact of geoengineering via stratospheric sulfate aerosol on the quasi-biennial oscillation (QBO) using the NASA Goddard Earth Observing System version 5 Chemistry Climate Model. We performed four 30 year simulations with a continuous injection of sulfur dioxide on the equator at 0° longitude. The four simulations differ by the amount of sulfur dioxide injected (5 Tg/yr and 2.5 Tg/yr) and the altitude of the injection (16 km-25 km and 22 km-25 km). We find that such an injection dramatically alters the quasi-biennial oscillation, prolonging the phase of easterly shear with respect to the control simulation. This is caused by the increased aerosol heating and associated warming in the tropical lower stratosphere and higher residual vertical velocity. In the case of maximum perturbation, i.e., highest stratospheric aerosol burden, the lower tropical stratosphere is locked into a permanent westerly QBO phase.

  4. Modifications of the Quasi-biennial Oscillation by a Geoengineering Perturbation of the Stratospheric Aerosol Layer

    NASA Technical Reports Server (NTRS)

    Aquila, V.; Garfinkel, C. I.; Newman, P. A.; Oman, L. D.; Waugh, D. W.

    2014-01-01

    This paper examines the impact of geoengineering via stratospheric sulfate aerosol on the quasi-biennial oscillation (QBO) using the NASA Goddard Earth Observing System (GEOS-5) Chemistry Climate Model. We performed four 30-year simulations with a continuous injection of sulfur dioxide on the equator at 0 degree longitude. The four simulations differ by the amount of sulfur dioxide injected (5Tg per year and 2.5 Tg per year) and the altitude of the injection (16km-25km and 22km-25km). We find that such an injection dramatically alters the quasi-biennial oscillation, prolonging the phase of easterly shear with respect to the control simulation. In the case of maximum perturbation, i.e. highest stratospheric aerosol burden, the lower tropical stratosphere is locked into a permanent westerly QBO phase. This locked QBO westerly phase is caused by the increased aerosol heating and associated warming in the tropical lower stratosphere.

  5. A new method of satellite-based haze aerosol monitoring over the North China Plain and a comparison with MODIS Collection 6 aerosol products

    NASA Astrophysics Data System (ADS)

    Yan, Xing; Shi, Wenzhong; Luo, Nana; Zhao, Wenji

    2016-05-01

    With worldwide urbanization, hazy weather has been increasingly frequent, especially in the North China Plain. However, haze aerosol monitoring remains a challenge. In this paper, MODerate resolution Imaging Spectroradiometer (MODIS) measurements were used to develop an enhanced haze aerosol retrieval algorithm (EHARA). This method can work not only on hazy days but also on normal weather days. Based on 12-year (2002-2014) Aerosol Robotic Network (AERONET) aerosol property data, empirical single scattering albedo (SSA) and asymmetry factor (AF) values were chosen to assist haze aerosol retrieval. For validation, EHARA aerosol optical thickness (AOT) values, along with MODIS Collection 6 (C6) dark-pixel and deep blue aerosol products, were compared with AERONET data. The results show that the EHARA can achieve greater AOT spatial coverage under hazy conditions with a high accuracy (73% within error range) and work a higher resolution (1-km). Additionally, this paper presents a comprehensive discussion of the differences between and limitations of the EHARA and the MODIS C6 DT land algorithms.

  6. Contribution of dissolved organic matter to submicron water-soluble organic aerosols in the marine boundary layer over the eastern equatorial Pacific

    NASA Astrophysics Data System (ADS)

    Miyazaki, Yuzo; Coburn, Sean; Ono, Kaori; Ho, David T.; Pierce, R. Bradley; Kawamura, Kimitaka; Volkamer, Rainer

    2016-06-01

    Stable carbon isotopic compositions of water-soluble organic carbon (WSOC) and organic molecular markers were measured to investigate the relative contributions of the sea surface sources to the water-soluble fraction of submicron organic aerosols collected over the eastern equatorial Pacific during the Tropical Ocean tRoposphere Exchange of Reactive halogens and Oxygenated VOCs (TORERO)/KA-12-01 cruise. On average, the water-soluble organic fraction of the total carbon (TC) mass in submicron aerosols was ˜ 30-35 % in the oceans with the low chlorophyll a (Chl a) concentrations, whereas it was ˜ 60 % in the high-Chl a regions. The average stable carbon isotope ratio of WSOC (δ13CWSOC) was -19.8 ± 2.0 ‰, which was systematically higher than that of TC (δ13CTC) (-21.8 ± 1.4 ‰). We found that in the oceans with both high and low Chl a concentrations the δ13CWSOC was close to the typical values of δ13C for dissolved organic carbon (DOC), ranging from -22 to -20 ‰ in surface seawater of the tropical Pacific Ocean. This suggests an enrichment of marine biological products in WSOC aerosols in the study region regardless of the oceanic area. In particular, enhanced levels of WSOC and biogenic organic marker compounds together with high values of WSOC / TC ( ˜ 60 %) and δ13CWSOC were observed over upwelling areas and phytoplankton blooms, which was attributed to planktonic tissues being more enriched in δ13C. The δ13C analysis estimated that, on average, marine sources contribute ˜ 90 ± 25 % of the aerosol carbon, indicating the predominance of marine-derived carbon in the submicron WSOC. This conclusion is supported by Lagrangian trajectory analysis, which suggests that the majority of the sampling points on the ship had been exposed to marine boundary layer (MBL) air for more than 80 % of the time during the previous 7 days. The combined analysis of the δ13C and monosaccharides, such as glucose and fructose, demonstrated that DOC concentration was

  7. Aerosol properties in Titan's upper atmosphere

    NASA Astrophysics Data System (ADS)

    Lavvas, Panayotis; Koskinen, Tommi; Royer, Emilie; Rannou, Pascal; West, Robert

    2016-06-01

    Multiple Cassini observations reveal that the abundant aerosol particles in Titan's atmosphere are formed at high altitudes, particularly in the thermosphere. They subsequently fall towards the lower atmosphere and in their path their size, shape, and population change in reflection to the variable atmospheric condition. Although multiple observations can help us retrieve information for the aerosol properties in the lower atmosphere, we have limited information for the aerosol properties between their formation region in the thermosphere and the upper region of the main haze layer or the detached aerosol layer. Observations at UV wavelengths are the only way to probe this part of the atmosphere and help us retrieve the aerosol properties. The presentation will provide an overview of the available observations, and discuss their implications for the production and evolution of Titan's aerosols.

  8. Aircraft measurements of ozone, NOx, CO, and aerosol concentrations in biomass burning smoke over Indonesia and Australia in October 1997: Depleted ozone layer at low altitude over Indonesia

    NASA Astrophysics Data System (ADS)

    Tsutsumi, Yukitomo; Sawa, Yousuke; Makino, Yukio; Jensen, Jørgen B.; Gras, John L.; Ryan, Brian F.; Diharto, Sri; Harjanto, Hery

    The 1997 El Niño unfolded as one of the most sever El Niño Southern Oscillation (ENSO) events in this century and it coincided with massive biomass burning in the equatorial western Pacific region. To assess the influence on the atmosphere, aircraft observations of trace gases and aerosol were conducted over Kalimantan in Indonesia and Australia. Over Kalimantan in Indonesia, high concentrations of O3, NOx, CO, and aerosols were observed during the flight. Although the aerosol and NOx decreased with altitude, the O3 had the maximum concentration (80.5 ppbv) in the middle layer of the smoke haze and recorded very low concentrations (˜20 ppbv) in the lower smoke layer. This feature was not observed in the Australian smoke. We proposed several hypotheses for the low O3 concentration at low levels over Kalimantan. The most likely are lack of solar radiation and losses at the surface of aerosol particles.

  9. 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.

  10. Long-Term Global Aerosol Products from NASA Reanalysis MERRA-2 Available at GES DISC

    NASA Astrophysics Data System (ADS)

    Shen, S.; Ostrenga, D.; Vollmer, B.

    2015-12-01

    Over 35 years of model simulated global aerosol products from NASA atmospheric reanalysis, second Modern-Era Retrospective analysis for Research and Applications (MERRA-2) are published in summer 2015 at NASA Goddard Earth Science Data and Information Services Center (GES DISC). The MERRA-2 covers the period 1980-present, continuing as an ongoing climate analysis. Aerosol assimilation is included throughout the period, using MODIS, MISR, AERONET, and AVHRR (in the pre-EOS period). The aerosols are assimilated by using the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model, which interact directly with the radiation parameterization, and radiatively coupled with atmospheric model dynamics in the Goddard Earth Observing System Model, Version 5 (GEOS-5). The data have been grouped into five datasets, including variables such as: dust column mass density, dust column mass density - PM 2.5, dust deposition, SO2 column mass density, aerosol optical depth analysis, total aerosol extinction AOT 550nm, black carbon emission etc. The data are available at hourly or 3-hourly and monthly at horizontal spatial resolution of 0.5x0.625 degrees (latitude x longitude) and 72 eta coordinate levels extending to 0.01 hPa for 3-dimensional variables. This presentation will document data access services at GES DISC and how to explore the data through the online visualization tool (Giovanni). As use cases, aerosol transportation of selected events will be demonstrated: a) SO2 column mass density from volcano Sierra Negra (Oct 2005), stayed in the tropical atmosphere for about 20 days; b) dust column mass density from a Asian dust storm in April 2001, transported dust from Asia across Pacific to North America in about one week; and c) black carbon column mass density from a wildfire late July to early September 2010 in Russia.

  11. Aerosol-cloud-drizzle interactions in warm boundary layer clouds using ground-based measurements from Atlantic and continental European sites

    NASA Astrophysics Data System (ADS)

    Mann, Julian; Chiu, Christine; Hogan, Robin; O'Connor, Ewan

    2013-04-01

    Aerosol impacts the climate directly through scattering and absorbing radiation, and indirectly through altering properties of clouds and precipitation. With increasing ambient aerosol concentration, it is agreed that the redistribution of cloud water to more numerous, but smaller cloud droplets suppresses precipitation. However, the magnitude of precipitation suppression is uncertain, and the response of total cloud water to aerosol concentration remains poorly observed and understood. To better understand how aerosols regulate macro- and microphysical properties of boundary-layer clouds, and to establish statistical relationships of aerosol-cloud-precipitation interactions, we analyze high-temporal resolution observations from the Atmospheric Radiation Measurement (ARM) Mobile Facility deployments in Germany in 2007 and in the Azores during 2009-2010. Through synergy between ground-based aerosol observing systems, active and passive remote sensing instruments, we will show how the drizzle rate at cloud base varies with aerosol concentration. We will also demonstrate how the probability of precipitation and the precipitation susceptibility respond to ambient aerosol concentration, and whether these responses agree with results from state-of-the-art satellite observations and climate models.

  12. Production of aerosols by optical catapulting: Imaging, performance parameters and laser-induced plasma sampling rate

    NASA Astrophysics Data System (ADS)

    Abdelhamid, M.; Fortes, F. J.; Fernández-Bravo, A.; Harith, M. A.; Laserna, J. J.

    2013-11-01

    Optical catapulting (OC) is a sampling and manipulation method that has been extensively studied in applications ranging from single cells in heterogeneous tissue samples to analysis of explosive residues in human fingerprints. Specifically, analysis of the catapulted material by means of laser-induced breakdown spectroscopy (LIBS) offers a promising approach for the inspection of solid particulate matter. In this work, we focus our attention in the experimental parameters to be optimized for a proper aerosol generation while increasing the particle density in the focal region sampled by LIBS. For this purpose we use shadowgraphy visualization as a diagnostic tool. Shadowgraphic images were acquired for studying the evolution and dynamics of solid aerosols produced by OC. Aluminum silicate particles (0.2-8 μm) were ejected from the substrate using a Q-switched Nd:YAG laser at 1064 nm, while time-resolved images recorded the propagation of the generated aerosol. For LIBS analysis and shadowgraphy visualization, a Q-switched Nd:YAG laser at 1064 nm and 532 nm was employed, respectively. Several parameters such as the time delay between pulses and the effect of laser fluence on the aerosol production have been also investigated. After optimization, the particle density in the sampling focal volume increases while improving the aerosol sampling rate till ca. 90%.

  13. Kinetics and Products of Heterogeneous Oxidation of Erythritol and Levoglucosan in Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Kessler, S. H.; Kroll, J. H.; Wilson, K. R.; Smith, J. D.

    2009-12-01

    Although organic aerosols in the atmosphere have been implicated in concerns related to both human health and global radiative forcing, they remain collectively a significant source of uncertainty in long-term predictions, in part because of the inherent chemical complexity of possible oxidation products formed from a given compound during its atmospheric lifetime. Here we study the heterogeneous oxidation of model compounds used as surrogates for biomass burning aerosol and secondary organic aerosol (SOA): levoglucosan, a frequently used tracer for biomass burning, and erythritol ((2R,3S)-butane-1,2,3,4-tetraol) an analog of the methyltetrols found in isoprene oxidation SOA. The present experiments are aimed at examining the kinetics and products of further oxidation of both compounds, in order both to explore how each compound contributes to atmospheric aerosol formation and to examine model single-component systems to determine how structural and compositional differences between compounds affect the relative paths of oxidative degradation. Particles are sent through a flow tube reactor where they are exposed to high concentrations (~1013 molecule1 s1 cm-3) of hydroxyl radicals (OH), after which the aerosols are sized and their composition analyzed using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) with both electron impact (EI) and vacuum-ultraviolet (VUV) ionization techniques. Although erythritol and levoglucosan have similar second-order degradation rate constants (2.03 ± 0.20 × 10-13 and 4.7 ± 0.5 × 10-13 cm3 molecule-1 s-1, respectively), the differences between the loss of particle mass upon an equivalent amount of oxidation (80% vs 30% respectively) are much more pronounced.

  14. Hygroscopicity of dicarbonyl-amine secondary organic aerosol products investigated with HTDMA

    NASA Astrophysics Data System (ADS)

    Hawkins, L. N.; de Haan, D. O.

    2010-12-01

    Recent studies have shown the importance of amine-dicarbonyl chemistry as a secondary organic aerosol (SOA) formation pathway, producing imines, imidazoles, and N-containing oligomers. Preliminary work in our group has suggested that some of these products may be surface active. Therefore, the presence of these products may result in important changes to submicron particle hygroscopicity that affect aerosol scattering and cloud condensation nuclei (CCN) activity, especially in regions with significant amine-containing particles. To investigate their hygroscopicity, we have designed a hygroscopicity tandem differential mobility analyzer (HTDMA) system around a 300 L Teflon chamber that allows for longer humidification times needed for some organic aerosol components that are only slightly hygroscopic. This modification provides a range of residence times from 2.5 minutes up to 1 hour, unlike previously published systems that vary from 2-30 seconds. Using the modified hygroscopicity tandem differential mobility analyzer (HTDMA), we have measured the hygroscopic growth factor (HGF) of SOA formed from reactions of glyoxal (and methylglyoxal) with methylamine, ammonium sulfate, and several amino acids. Changes to inorganic aerosol HGF in response to the presence of SOA products are also investigated.

  15. Observed aerosol-induced radiative effect on plant productivity in the eastern United States

    NASA Astrophysics Data System (ADS)

    Strada, S.; Unger, N.; Yue, X.

    2015-12-01

    We apply satellite observations of aerosol optical depth (AOD) in conjunction with flux tower-derived estimates of gross primary productivity (GPP) to probe the relationship between atmospheric aerosol loading and carbon uptake rate at 10 select sites (4 deciduous broadleaf, 3 cropland, 1 evergreen needle leaf, 1 mixed forest and 1 grassland) on hourly time scales in the growing season in the eastern United States. For deciduous and mixed forests, the aerosol light scattering increases GPP with a maximum effect observed under polluted conditions (AOD >0.6), when diffuse radiation is 40-60%. During midday hours, high AOD conditions (>0.4) enhance plant productivity by ∼13% in deciduous forests. In contrast, we find that high diffuse light fraction does not increase the carbon uptake rate in croplands and grasslands; for these ecosystems, we estimate that high AOD conditions reduce GPP by ∼17% during midday hours. Our findings are consistent with previous studies that have attributed these contrasting response sensitivities to the complex and closed canopy architecture of forests versus crops and grasslands. C4 but not C3 crops may benefit from pollution-induced changes in diffuse and direct light. Further research is needed to investigate the role of local meteorology as a possible confounder in the connection between atmospheric aerosols and plant productivity.

  16. Modelling non-equilibrium secondary organic aerosol formation and evaporation with the aerosol dynamics, gas- and particle-phase chemistry kinetic multi-layer model ADCHAM

    NASA Astrophysics Data System (ADS)

    Roldin, P.; Eriksson, A. C.; Nordin, E. Z.; Hermansson, E.; Mogensen, D.; Rusanen, A.; Boy, M.; Swietlicki, E.; Svenningsson, B.; Zelenyuk, A.; Pagels, J.

    2014-01-01

    We have developed the novel Aerosol Dynamics, gas- and particle-phase chemistry model for laboratory CHAMber studies (ADCHAM). The model combines the detailed gas phase Master Chemical Mechanism version 3.2, an aerosol dynamics and particle phase chemistry module (which considers acid catalysed oligomerization, heterogeneous oxidation reactions in the particle phase and non-ideal interactions between organic compounds, water and inorganic ions) and a kinetic multilayer module for diffusion limited transport of compounds between the gas phase, particle surface and particle bulk phase. In this article we describe and use ADCHAM to study: (1) the mass transfer limited uptake of ammonia (NH3) and formation of organic salts between ammonium (NH4+) and carboxylic acids (RCOOH), (2) the slow and almost particle size independent evaporation of α-pinene secondary organic aerosol (SOA) particles, and (3) the influence of chamber wall effects on the observed SOA formation in smog chambers. ADCHAM is able to capture the observed α-pinene SOA mass increase in the presence of NH3(g). Organic salts of ammonium and carboxylic acids predominantly form during the early stage of SOA formation. These salts contribute substantially to the initial growth of the homogeneously nucleated particles. The model simulations of evaporating α-pinene SOA particles support the recent experimental findings that these particles have a semi-solid tar like amorphous phase state. ADCHAM is able to reproduce the main features of the observed slow evaporation rates if low-volatility and viscous oligomerized SOA material accumulates in the particle surface layer upon evaporation. The evaporation rate is mainly governed by the reversible decomposition of oligomers back to monomers. Finally, we demonstrate that the mass transfer limited uptake of condensable organic compounds onto wall deposited particles or directly onto the Teflon chamber walls of smog chambers can have profound influence on the

  17. Optical and microphysical characterization of aerosol layers over South Africa by means of multi-wavelength depolarization and Raman lidar measurements

    NASA Astrophysics Data System (ADS)

    Giannakaki, Elina; van Zyl, Pieter G.; Müller, Detlef; Balis, Dimitris; Komppula, Mika

    2016-07-01

    Optical and microphysical properties of different aerosol types over South Africa measured with a multi-wavelength polarization Raman lidar are presented. This study could assist in bridging existing gaps relating to aerosol properties over South Africa, since limited long-term data of this type are available for this region. The observations were performed under the framework of the EUCAARI campaign in Elandsfontein. The multi-wavelength PollyXT Raman lidar system was used to determine vertical profiles of the aerosol optical properties, i.e. extinction and backscatter coefficients, Ångström exponents, lidar ratio and depolarization ratio. The mean microphysical aerosol properties, i.e. effective radius and single-scattering albedo, were retrieved with an advanced inversion algorithm. Clear differences were observed for the intensive optical properties of atmospheric layers of biomass burning and urban/industrial aerosols. Our results reveal a wide range of optical and microphysical parameters for biomass burning aerosols. This indicates probable mixing of biomass burning aerosols with desert dust particles, as well as the possible continuous influence of urban/industrial aerosol load in the region. The lidar ratio at 355 nm, the lidar ratio at 532 nm, the linear particle depolarization ratio at 355 nm and the extinction-related Ångström exponent from 355 to 532 nm were 52 ± 7 sr, 41 ± 13 sr, 0.9 ± 0.4 % and 2.3 ± 0.5, respectively, for urban/industrial aerosols, while these values were 92 ± 10 sr, 75 ± 14 sr, 3.2 ± 1.3 % and 1.7 ± 0.3, respectively, for biomass burning aerosol layers. Biomass burning particles are larger and slightly less absorbing compared to urban/industrial aerosols. The particle effective radius were found to be 0.10 ± 0.03, 0.17 ± 0.04 and 0.13 ± 0.03 µm for urban/industrial, biomass burning, and mixed aerosols, respectively, while the single-scattering albedo at 532 nm was 0.87 ± 0.06, 0.90 ± 0.06, and 0.88 ± 0.07 (at 532

  18. Major Influence of Tropical Volcanic Eruptions on the Stratospheric Aerosol Layer During the Last Decade

    NASA Technical Reports Server (NTRS)

    Vernier, Jean-Paul; Thomason, Larry W.; Pommereau, J.-P.; Bourassa, Adam; Pelon, Jacques; Garnier, Anne; Hauchecorne, A.; Blanot, L.; Trepte, Charles R.; Degenstein, Doug; Vargas, F.

    2011-01-01

    The variability of stratospheric aerosol loading between 1985 and 2010 is explored with measurements from SAGE II, CALIPSO, GOMOS/ENVISAT, and OSIRIS/Odin space-based instruments. We find that, following the 1991 eruption of Mount Pinatubo, stratospheric aerosol levels increased by as much as two orders of magnitude and only reached background levels between 1998 and 2002. From 2002 onwards, a systematic increase has been reported by a number of investigators. Recently, the trend, based on ground-based lidar measurements, has been tentatively attributed to an increase of SO2 entering the stratosphere associated with coal burning in Southeast Asia. However, we demonstrate with these satellite measurements that the observed trend is mainly driven by a series of moderate but increasingly intense volcanic eruptions primarily at tropical latitudes. These events injected sulfur directly to altitudes between 18 and 20 km. The resulting aerosol particles are slowly lofted into the middle stratosphere by the Brewer-Dobson circulation and are eventually transported to higher latitudes.

  19. Formation and evolution of molecular products in α-pinene secondary organic aerosol.

    PubMed

    Zhang, Xuan; McVay, Renee C; Huang, Dan D; Dalleska, Nathan F; Aumont, Bernard; Flagan, Richard C; Seinfeld, John H

    2015-11-17

    Much of our understanding of atmospheric secondary organic aerosol (SOA) formation from volatile organic compounds derives from laboratory chamber measurements, including mass yield and elemental composition. These measurements alone are insufficient to identify the chemical mechanisms of SOA production. We present here a comprehensive dataset on the molecular identity, abundance, and kinetics of α-pinene SOA, a canonical system that has received much attention owing to its importance as an organic aerosol source in the pristine atmosphere. Identified organic species account for ∼58-72% of the α-pinene SOA mass, and are characterized as semivolatile/low-volatility monomers and extremely low volatility dimers, which exhibit comparable oxidation states yet different functionalities. Features of the α-pinene SOA formation process are revealed for the first time, to our knowledge, from the dynamics of individual particle-phase components. Although monomeric products dominate the overall aerosol mass, rapid production of dimers plays a key role in initiating particle growth. Continuous production of monomers is observed after the parent α-pinene is consumed, which cannot be explained solely by gas-phase photochemical production. Additionally, distinct responses of monomers and dimers to α-pinene oxidation by ozone vs. hydroxyl radicals, temperature, and relative humidity are observed. Gas-phase radical combination reactions together with condensed phase rearrangement of labile molecules potentially explain the newly characterized SOA features, thereby opening up further avenues for understanding formation and evolution mechanisms of α-pinene SOA. PMID:26578760

  20. Development of a double-layered ceramic filter for aerosol filtration at high-temperatures: the filter collection efficiency.

    PubMed

    de Freitas, Normanda L; Gonçalves, José A S; Innocentini, Murilo D M; Coury, José R

    2006-08-25

    The performance of double-layered ceramic filters for aerosol filtration at high temperatures was evaluated in this work. The filtering structure was composed of two layers: a thin granular membrane deposited on a reticulate ceramic support of high porosity. The goal was to minimize the high pressure drop inherent of granular structures, without decreasing their high collection efficiency for small particles. The reticulate support was developed using the technique of ceramic replication of polyurethane foam substrates of 45 and 75 pores per inch (ppi). The filtering membrane was prepared by depositing a thin layer of granular alumina-clay paste on one face of the support. Filters had their permeability and fractional collection efficiency analyzed for filtration of an airborne suspension of phosphatic rock in temperatures ranging from ambient to 700 degrees C. Results revealed that collection efficiency decreased with gas temperature and was enhanced with filtration time. Also, the support layer influenced the collection efficiency: the 75 ppi support was more effective than the 45 ppi. Particle collection efficiency dropped considerably for particles below 2 microm in diameter. The maximum collection occurred for particle diameters of approximately 3 microm, and decreased again for diameters between 4 and 8 microm. Such trend was successfully represented by the proposed correlation, which is based on the classical mechanisms acting on particle collection. Inertial impaction seems to be the predominant collection mechanism, with particle bouncing/re-entrainment acting as detachment mechanisms.

  1. A consistent aerosol optical depth (AOD) dataset over mainland China by integration of several AOD products

    NASA Astrophysics Data System (ADS)

    Xu, H.; Guang, J.; Xue, Y.; de Leeuw, Gerrit; Che, Y. H.; Guo, Jianping; He, X. W.; Wang, T. K.

    2015-08-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS), the Multiangle Imaging Spectroradiometer (MISR) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) provide validated aerosol optical depth (AOD) products over both land and ocean. However, the values of the AOD provided by each of these satellites may show spatial and temporal differences due to the instrument characteristics and aerosol retrieval algorithms used for each instrument. In this article we present a method to produce an AOD data set over Asia for the year 2007 based on fusion of the data provided by different instruments and/or algorithms. First, the bias of each satellite-derived AOD product was calculated by comparison with ground-based AOD data derived from the AErosol RObotic NETwork (AERONET) and the China Aerosol Remote Sensing NETwork (CARSNET) for different values of the surface albedo and the AOD. Then, these multiple AOD products were combined using the maximum likelihood estimate (MLE) method using weights derived from the root mean square error (RMSE) associated with the accuracies of the original AOD products. The original and merged AOD dataset has been validated by comparison with AOD data from the CARSNET. Results show that the mean bias error (MBE) and mean absolute error (MAE) of the merged AOD dataset are not larger than that of any of the original AOD products. In addition, for the merged AOD dataset the fraction of pixels with no data is significantly smaller than that of any of the original products, thus increasing the spatial coverage. The fraction of retrievable area is about 50% for the merged AOD dataset and between 5% and 20% for the MISR, SeaWiFS, MODIS-DT and MODIS-DB algorithms.

  2. Monoterpene oxidation products and organosulfates in aerosols during BEARPEX 2007 and 2009

    NASA Astrophysics Data System (ADS)

    Glasius, Marianne; Kristensen, Kasper; Worton, David R.; Goldstein, Allen H.

    2010-05-01

    Organosulfate esters of oxidation products of monoterpenes and isoprene have been identified in aerosols from both laboratory and field studies. While the exact route of formation of organosulfates is still ambiguous, these compounds pose an interesting coupling between anthropogenic emissions and biogenic oxidation products in secondary organic aerosols (SOA). We present measurements of monoterpene oxidation products, organosulfates and nitroxy organosulfates in aerosols collected during the Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX) in California during late summer 2007 and summer 2009. The study site was located in a Ponderosa pine plantation affected by regional transport of air pollutants. Particles (PM2.5) were collected as one night-time and two daytime samples per day using a high volume sampler. After extraction of filters, polar organic compounds were analysed by HPLC coupled through an electrospray inlet to a quadrupole time-of-flight mass spectrometer (qTOF-MS). Standards of adipic, cis-pinic and pinonic acids were used for quantification, while camphor sulphonic acid was used as a surrogate standard for organosulfate compounds. Organosulfate esters can be identified from their MS-fragments (HSO4- and SO3-) and the isotopic pattern of sulphur. Concentrations of adipic acid and the terpene oxidation products cis-pinic acid and pinonic acid (from α- and β-pinene) were quantified. The relative concentrations between samples of terpenylic acid, diterpenylic acid and 2-hydroxyterpenylic acid were also investigated. Organosulfate esters and nitroxy organosulfate esters of α-pinene, β-pinene, limonene and isoprene, as well as their oxidation products, were identified based on their molecular mass and fragmentation patterns. Concentrations of some nitroxy organosulfate esters generally increased during night compared to day-time. Their formation thus seems to be related to reactions involving nitrate radicals at night-time.

  3. United role of radon decay products and nano-aerosols in radon dosimetry

    NASA Astrophysics Data System (ADS)

    Smerajec, M.; Vaupotič, J.

    2012-04-01

    The major part of human exposure to natural radiation originates from inhalation of radon (Rn) and radon short-lived decay products (RnDP: 218Po, 214Pb, 214Bi and 214Po). RnDP are formed as a result of α-transformation of radon. In the beginning they are positive ions which neutralize and form clusters with air molecules, and later partly attach to background aerosol particles in indoor air. Eventually, they appear as radioactive nano-aerosols with a bimodal size distribution in ranges of 1-10 nm (unattached RnDP) and of 200-800 nm (attached RnDP). When inhaled, they are deposited in the respiratory tract. Deposition is more efficient for smaller particles. Therefore, the fraction (fun) of the unattached RnDP, which appears to be influenced by the number concentration and size distribution of general (background) aerosols in the ambient air, has a crucial role in radon dosimetry. Radon, radon decay products and general aerosols have been monitored simultaneously in the kitchen of a typical rural house under real living conditions, also comprising four human activities generating particular matter: cooking and baking, as two typical activities in kitchen, and cigarette smoking and candle burning. In periods without any human activity, the total number concentration of general aerosol ranged from 1000 to 3000 cm-3,with the geometric mean of particle diameter in the range of 60-68 nm and with 0.1-1 % of particles smaller than 10 nm. Preparation of coffee changed the concentration to 193,000 cm-3, the geometric mean of diameter to 20 nm and fraction of particles smaller than 10 nm to 11 %. The respective changes were for baking cake: 503,000 cm-3, 17 nm and 19 %, for smoking:423,000 cm-3, 83 nm and 0.4 %, and forcandle burning: 945,000 cm-3, 8 nm and 85 %. While, as expected, a reduction of fun was observed during cooking, baking and smoking, when larger particles were emitted, fun did not increase during candle burning with mostly particles smaller than 10 nm

  4. Monitoring the impact of aerosol contamination on the drought-induced decline of gross primary productivity

    NASA Astrophysics Data System (ADS)

    Zhang, Yao; Li, Weizhong; Zhu, Qiuan; Chen, Huai; Fang, Xiuqin; Zhang, Tinglong; Zhao, Pengxiang; Peng, Changhui

    2015-04-01

    Southwestern China experienced a period of severe drought from September 2009 to May 2010. It led to widespread decline in the enhanced vegetation index (EVI) and gross primary productivity (GPP) in the springtime of 2010 (March to May). However, this study observed a spatial inconsistency between drought-impacted vegetation decline and the precipitation deficit. Significant aerosol loads that correspond to inconsistent areas were also observed during the drought period. After analyzing both MODIS GPP/NPP Collection 5 (C5) and the newer Collection 5.5 (C55) data, a large area observed to be experiencing GPP decline in the eastern part of the study area proved to be unreliable. Based on EVI data, after atmospherically contaminated data were screened from analysis, approximately 20% of the study area exhibited browning whereas 33% displayed no change or greening and the remaining area (approximately 47%) lacked sufficient data to document changing conditions. Correlation analysis showed that fire occurrences, aerosol optical depth, and precipitation anomalies during the two drought periods (from September to February and from March to May) all contributed to a decrease in GPP. C55 data remains vulnerable to aerosol contamination due to a much higher correlation coefficient with aerosol optical depth compared to C5 data. In the future, users of remotely sensed data should be cautious of and take into account impacts related to atmospheric contamination, even during drought periods.

  5. Double blanket effect caused by two layers of black carbon aerosols escalates warming in the Brahmaputra River Valley.

    PubMed

    Rahul, P R C; Bhawar, R L; Ayantika, D C; Panicker, A S; Safai, P D; Tharaprabhakaran, V; Padmakumari, B; Raju, M P

    2014-01-14

    First ever 3-day aircraft observations of vertical profiles of Black Carbon (BC) were obtained during the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) conducted on 30(th) August, 4(th) and 6(th) September 2009 over Guwahati (26° 11'N, 91° 44'E), the largest metropolitan city in the Brahmaputra River Valley (BRV) region. The results revealed that apart from the surface/near surface loading of BC due to anthropogenic processes causing a heating of 2 K/day, the large-scale Walker and Hadley atmospheric circulations associated with the Indian summer monsoon help in the formation of a second layer of black carbon in the upper atmosphere, which generates an upper atmospheric heating of ~2 K/day. Lofting of BC aerosols by these large-scale circulating atmospheric cells to the upper atmosphere (4-6 Km) could also be the reason for extreme climate change scenarios that are being witnessed in the BRV region.

  6. Double blanket effect caused by two layers of black carbon aerosols escalates warming in the Brahmaputra River Valley

    PubMed Central

    Rahul, P. R. C.; Bhawar, R. L.; Ayantika, D. C.; Panicker, A. S.; Safai, P. D.; Tharaprabhakaran, V.; Padmakumari, B.; Raju, M. P.

    2014-01-01

    First ever 3-day aircraft observations of vertical profiles of Black Carbon (BC) were obtained during the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) conducted on 30th August, 4th and 6th September 2009 over Guwahati (26°11′N, 91°44′E), the largest metropolitan city in the Brahmaputra River Valley (BRV) region. The results revealed that apart from the surface/near surface loading of BC due to anthropogenic processes causing a heating of 2 K/day, the large-scale Walker and Hadley atmospheric circulations associated with the Indian summer monsoon help in the formation of a second layer of black carbon in the upper atmosphere, which generates an upper atmospheric heating of ~2 K/day. Lofting of BC aerosols by these large-scale circulating atmospheric cells to the upper atmosphere (4–6 Km) could also be the reason for extreme climate change scenarios that are being witnessed in the BRV region. PMID:24419075

  7. Observational Constraints on Glyoxal Production from Isoprene Oxidation and Its Contribution to Organic Aerosol Over the Southeast United States

    NASA Astrophysics Data System (ADS)

    Li, J.; Mao, J.; Min, K. E.; Washenfelder, R. A.; Brown, S. S.; Kaiser, J.; Keutsch, F. N.; Wolfe, G. M.; Hanisco, T. F.; Pollack, I. B.; Ryerson, T. B.; Graus, M.; Gilman, J.; Lerner, B. M.; Warneke, C.; De Gouw, J. A.; Middlebrook, A. M.; Henderson, B. H.; Paulot, F.; Horowitz, L. W.; Liao, J.; Welti, A.

    2015-12-01

    We use observations from the NOAA Southeast Nexus (SENEX) aircraft campaign, evaluated with a nudged global chemistry-climate model, to better understand the sources and sinks of glyoxal over the Southeast United States. We find that the model with an isoprene oxidation mechanism that does not account for δ-hydroxyl peroxy radicals (δ-ISOPO2), can better reproduce the observed vertical profiles of glyoxal and HCHO, as well as their correlation (RGF) in the continental boundary layer. The suppression of δ-ISOPO2 is consistent with recent theoretical and laboratory studies, reflecting different fates of δ-ISOPO2 under chamber conditions (NO > 100 ppbv) vs. ambient conditions (NO ~ 0.1 ppbv). By including a reactive uptake of glyoxal in the model (γglyx=2.9×10-3), we find that this improves modeled glyoxal in the surface layer but leads to an underestimate of glyoxal above the surface. We estimate an upper limit (1.0 μg/m3) for SOA contributed by glyoxal uptake by aerosols and clouds in the boundary layer of this region. Our work highlights several uncertainties in current chemical mechanisms on glyoxal production from isoprene oxidation under high and low NOx conditions, which may lead to large biases in the estimates of its contribution to SOA formation. Further investigation on these pathways is warranted to quantify the sources and sinks of glyoxal in regional and global scales.

  8. Scattering and absorption properties of near-surface aerosol over Gangetic-Himalayan region: the role of boundary layer dynamics and long-range transport

    NASA Astrophysics Data System (ADS)

    Dumka, U. C.; Kaskaoutis, D. G.; Srivastava, M. K.; Devara, P. C. S.

    2014-08-01

    Knowledge of light scattering and absorption properties of atmospheric aerosols is of vital importance in evaluating their types, sources and radiative forcing. This is of particular interest over the Gangetic-Himalayan (GH) region due to large aerosol loading over the plains and the uplift over the Himalayan range causing serious effects on atmospheric heating, glaciology and monsoon circulation. In this respect, Ganges Valley Aerosol Experiment (GVAX) was initiated over the region aiming to examine the aerosol properties, source regions, uplift mechanisms and aerosol-cloud interactions. The present study examines the temporal (monthly, seasonal) evolution of scattering (σsp) and absorption (σap) coefficients, their wavelength dependence, and the role of the Indo-Gangetic plains (IGP), boundary-layer dynamics (BLD) and long-range transport (LRT) in the aerosol uplift over the Himalayas. The measurements are performed at the elevated site Nainital via the Atmospheric Radiation Measurement Mobile Facility including several instruments (Nephelometer, Particle Soot Absorption Photometer, etc.) during June 2011 to March 2012. The σsp and σap exhibit a pronounced seasonal variation with monsoon low and post-monsoon (November) high, while the scattering wavelength exponent exhibits higher values during monsoon, in contrast to the absorption Ångström exponent which maximizes in December-March. The analysis is performed separately for particles bellow 10 and 1μm in diameter in order to examine the influence of the particle size on optical properties. The elevated-background measuring site provides the advantage of examining the LRT of natural and anthropogenic aerosols from the IGP and southwest Asia and the role of BLD in the aerosol lifting processes, while the aerosols are found to be well-mixed and aged-type dominant.

  9. A new operational EUMETSAT product for the retrieval of aerosol optical properties over land (PMAp v2)

    NASA Astrophysics Data System (ADS)

    Grzegorski, Michael; Munro, Rosemary; Poli, Gabriele; Holdak, Andriy; Lang, Ruediger

    2016-04-01

    The retrieval of aerosol optical properties is an important task to provide data for industry and climate forecasting. An ideal instrument should include observations with moderate spectral and high spatial resolution for a wide range of wavelengths (from the UV to the TIR), measurements of the polarization state at different wavelengths and measurements of the same scene for different observation geometries. As such an ideal instrument is currently unavailable the usage of different instruments on one satellite platform is an alternative choice. Since February 2014, the Polar Multi sensor Aerosol product (PMAp) has been delivered as an operational GOME product to our customers. The algorithm retrieves aerosol optical properties over ocean (AOD, volcanic ash, aerosol type) using a multi-sensor approach (GOME, AVHRR, IASI). The product is now extended to pixels over land using a new release of the operational PMAp processor (PMAp v2). The pre-operational data dissemination of the new PMAp v2 data to our users is scheduled for March 2016. This presentation gives an overview on the new operational product PMAp v2 with a focus on the validation of the PMAp aerosol optical depth over land. The impact of different error sources on the results (e.g. surface contribution to the TOA reflectance) is discussed. We also show first results of upcoming extensions of our PMAp processor, in particular the improvement of the cloud/aerosol discrimination of thick aerosol events (e.g. volcanic ash plumes, desert dust outbreaks).

  10. A Simple Apparatus for the Injection of Lithium Aerosol into the Scrape-Off Layer of Fusion Research Devices

    SciTech Connect

    D. K. Mansfield, A.L Roquemore, H. Schneider, J. Timberlake, H. Kugel, M.G. Bell and the NSTX Research Team

    2010-10-11

    A simple device has been developed to deposit elemental lithium onto plasma facing components in the National Spherical Torus Experiment. Deposition is accomplished by dropping lithium powder into the plasma column. Once introduced, lithium particles quickly become entrained in scrape-off layer flow as an evaporating aerosol. Particles are delivered through a small central aperture in a computer-controlled resonating piezoelectric disk on which the powder is supported. The device has been used to deposit lithium both during discharges as well as prior to plasma breakdown. Clear improvements to plasma performance have been demonstrated. The use of this apparatus provides flexibility in the amount and timing of lithium deposition and, therefore, may benefit future fusion research devices.

  11. Airborne Lidar measurements of aerosols, mixed layer heights, and ozone during the 1980 PEPE/NEROS summer field experiment

    NASA Technical Reports Server (NTRS)

    Browell, E. V.; Shipley, S. T.; Butler, C. F.; Ismail, S.

    1985-01-01

    A detailed summary of the NASA Ultraviolet Differential Absorption Lidar (UV DIAL) data archive obtained during the EPA Persistent Elevated Pollution Episode/Northeast Regional Oxidant Study (PEPE/NEROS) Summer Field Experiment Program (July through August 1980) is presented. The UV dial data set consists of remote measurements of mixed layer heights, aerosol backscatter cross sections, and sequential ozone profiles taken during 14 long-range flights onboard the NASA Wallops Flight Center Electra aircraft. These data are presented in graphic and tabular form, and they have been submitted to the PEPE/NEROS data archive on digital magnetic tape. The derivation of mixing heights and ozone profiles from UV Dial signals is discussed, and detailed intercomparisons with measurements obtained by in situ sensors are presented.

  12. DETERMINATION OF SECONDARY ORGANIC AEROSOL PRODUCTS FROM THE PHOTOOXIDATION OF TOLUENE AND THEIR IMPLICATIONS IN AMBIENT PM2.5

    EPA Science Inventory

    Laboratory study was carried out to investigate the secondary organic aerosol products from photooxidation of the aromatic hydrocarbon toluene. The laboratory experiments consisted of irradiating toluene/propylene/NOX/air mixtures in a smog chamber operated in the dynamic mode...

  13. The optical, physical and chemical properties of the products of glyoxal uptake on ammonium sulfate seed aerosols

    NASA Astrophysics Data System (ADS)

    Trainic, M.; Riziq, A. A.; Lavi, A.; Flores, J. M.; Rudich, Y.

    2011-07-01

    The heterogeneous reaction between gas phase glyoxal and ammonium sulfate (AS) aerosols, a proxy for inorganic atmospheric aerosol, was studied in terms of the dependence of the optical, physical and chemical properties of the product aerosols on initial particle size and ambient RH. The reactions were studied under different relative humidity (RH) conditions, varying from dry conditions (~20 % RH) and up to 90 % RH, covering conditions prevalent in many atmospheric environments. At λ = 355 nm, the reacted aerosols demonstrate a substantial growth in optical extinction cross section, as well as in mobility diameter under a broad range of RH values (35-90 %). The ratio of the product aerosol to seed aerosol geometric cross section reached up to ~3.5, and the optical extinction cross-section up to ~250. The reactions show a trend of increasing physical and optical growth with decreasing seed aerosol size, from 100nm to 300 nm, as well as with decreasing RH values from 90 % to ~40 %. Optically inactive aerosols, at the limit of the Mie range (100 nm diameter) become optically active as they grow due to the reaction. AMS analyses of the reaction of 300 nm AS at RH values of 50 %, 75 % and 90 % show that the main products of the reaction are glyoxal oligomers, formed by acetal formation in the presence of AS. In addition, imidazole formation, which is a minor channel, is observed for all reactions, yielding a product which absorbs at λ = 290 nm, with possible implications on the radiative properties of the product aerosols. The ratio of absorbing substances (C-N compounds, including imidazoles) increases with increasing RH value. A core/shell model used for the investigation of the optical properties of the reaction products of AS 300nm with gas phase glyoxal, shows that the refractive index (RI) of the reaction products are in the range between 1.57-1.71 for the real part and between 0-0.02 for the imaginary part of the RI at 355 nm. The observed increase in the

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

    NASA Astrophysics Data System (ADS)

    Wood, R.

    2012-12-01

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

  15. The influence of marine microbial activities on aerosol production: A laboratory mesocosm study

    NASA Astrophysics Data System (ADS)

    Alpert, Peter A.; Kilthau, Wendy P.; Bothe, Dylan W.; Radway, JoAnn C.; Aller, Josephine Y.; Knopf, Daniel A.

    2015-09-01

    The oceans cover most of the Earth's surface, contain nearly half the total global primary biomass productivity, and are a major source of atmospheric aerosol particles. Here we experimentally investigate links between biological activity in seawater and sea spray aerosol (SSA) flux, a relationship of potential significance for organic aerosol loading and cloud formation over the oceans and thus for climate globally. Bubbles were generated in laboratory mesocosm experiments either by recirculating impinging water jets or glass frits. Experiments were conducted with Atlantic Ocean seawater collected off the eastern end of Long Island, NY, and with artificial seawater containing cultures of bacteria and phytoplankton Thalassiosira pseudonana, Emiliania huxleyi, and Nannochloris atomus. Changes in SSA size distributions occurred during all phases of bacterial and phytoplankton growth, as characterized by cell concentrations, dissolved organic carbon, total particulate carbon, and transparent exopolymer particles (gel-forming polysaccharides representing a major component of biogenic exudate material). Over a 2 week growth period, SSA particle concentrations increased by a factor of less than 2 when only bacteria were present and by a factor of about 3 when bacteria and phytoplankton were present. Production of jet-generated SSA particles of diameter less than 200 nm increased with time, while production of all particle diameters increased with time when frits were used. The implications of a marine biological activity dependent SSA flux are discussed.

  16. Regional aerosol properties: Comparisons of boundary layer measurements from ACE 1, ACE 2, Aerosols99, INDOEX, ACE Asia, TARFOX, and NEAQS

    NASA Astrophysics Data System (ADS)

    Quinn, Patricia K.; Bates, Timothy S.

    2005-07-01

    Means and variability of aerosol chemical composition and optical properties are compared for the first and second Aerosol Characterization Experiments (ACE 1 and ACE 2), a cruise across the Atlantic (Aerosols99), the Indian Ocean Experiment (INDOEX), the Asian Aerosol Characterization Experiment (ACE Asia), the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX), and the New England Air Quality Study (NEAQS). These experiments were focused either on the remote marine atmosphere (ACE 1) or areas downwind of continental aerosol source regions including western Europe, North America, Africa, India, and Asia. Presented here are size-segregated concentrations of aerosol mass, sea salt, non-sea-salt (nss) SO4=, NH4+, NO3-, dust, organic carbon (OC), elemental carbon (EC), and nss K+, as well as mass ratios that are commonly used to identify aerosol sources and to assess aerosol processing (Cl- to Na+, OC to nss SO4=, EC to total carbon (TC), EC to nss SO4=, nss K+ to EC, Fe to Al, and Si to Al). Optical properties that are compared include size-segregated scattering, backscattering, and absorption coefficients, and single-scattering albedo at 550 nm. Size-segregated mass scattering and mass absorption efficiencies for the total aerosol and mass extinction efficiencies for the dominant chemical components also are compared. In addition, we present the contribution to light extinction by the dominant chemical components for each region. All data are based on shipboard measurements performed at a relative humidity of 55 ± 5%. Scattering coefficients and single-scattering albedos also are reported at ambient relative humidity (RH) using published values of f(RH). Finally, aerosol optical depths from each region are compared. Identical sampling protocols were used in all experiments in order to eliminate sampling biases and to make the data directly comparable. Major findings include (1) nss SO4= makes up only 16 to 46% of the submicron aerosol mass

  17. Clouds, Aerosol, and Precipitation in the Marine Boundary Layer: Analysis of Results from the ARM Mobile Facility Deployment to the Azores (2009/2010)

    SciTech Connect

    Wood, Robert

    2013-05-31

    The project focuses upon dataset analysis and synthesis of datasets from the AMF deployment entitled “Clouds, Aerosols, and Precipitation in the Marine Boundary Layer (CAP-MBL)” at Graciosa Island in the Azores. Wood is serving a PI for this AMF deployment.

  18. 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

  19. Industrial-scale spray layer-by-layer assembly for production of biomimetic photonic systems.

    PubMed

    Krogman, K C; Cohen, R E; Hammond, P T; Rubner, M F; Wang, B N

    2013-12-01

    Layer-by-layer assembly is a powerful and flexible thin film process that has successfully reproduced biomimetic photonic systems such as structural colour. While most of the seminal work has been carried out using slow and ultimately unscalable immersion assembly, recent developments using spray layer-by-layer assembly provide a platform for addressing challenges to scale-up and manufacturability. A series of manufacturing systems has been developed to increase production throughput by orders of magnitude, making commercialized structural colour possible. Inspired by biomimetic photonic structures we developed and demonstrated a heat management system that relies on constructive reflection of near infrared radiation to bring about dramatic reductions in heat content. PMID:24263056

  20. Application Protocol, Initial Graphics Exchange Specification (IGES), Layered Electrical Product

    SciTech Connect

    O`Connell, L.J.

    1994-12-01

    An application protocol is an information systems engineering view of a specific product The view represents an agreement on the generic activities needed to design and fabricate the product the agreement on the information needed to support those activities, and the specific constructs of a product data standard for use in transferring some or all of the information required. This application protocol describes the data for electrical and electronic products in terms of a product description standard called the Initial Graphics Exchange Specification (IGES). More specifically, the Layered Electrical Product IGES Application Protocol (AP) specifies the mechanisms for defining and exchanging computer-models and their associated data for those products which have been designed in two dimensional geometry so as to be produced as a series of layers in IGES format The AP defines the appropriateness of the data items for describing the geometry of the various parts of a product (shape and location), the connectivity, and the processing and material characteristics. Excluded is the behavioral requirements which the product was intended to satisfy, except as those requirements have been recorded as design rules or product testing requirements.

  1. Aerosol transport and dispersion measurements in the near surface boundary layer

    NASA Astrophysics Data System (ADS)

    Hiscox, April Lynn

    The studies presented in this dissertation present new techniques for measuring aerosols in the atmosphere, and the application of these techniques to three different aerosol sources. A methodology for measuring dispersion parameters based on lidar images, which can be used as an efficient way to remotely monitor time variations of plume dispersion parameters, is presented. Lidar images of a smoke plume cross-section over a forest canopy during nighttime conditions are analyzed to estimate vertical dispersion parameters and vertical meander of the plume centerline in the near field. Dispersion parameters 60 meters downwind are found to have a median value of 2.31 meters. Measurements of these parameters have not previously been made outside the restraints of a wind tunnel experiment. A second technique to measure in-plume concentrations based on single wavelength lidar images is also presented. A field study of aerial spray movement and dispersion was used to determine in-plume spray concentrations of very fine droplets applied during calm, stable atmospheric conditions. Supporting meteorology and air turbulence measurements were made simultaneously with 3-D sonic anemometers. The amount of spray material remaining in the air decreased rapidly for 1--2 minutes, and thereafter remained nearly constant and drifted as a definable plume with the slight air currents. Finally, these two techniques are applied to measure near-field spatial dynamics, spread and concentrations of dust plumes emitted during tilling and harvesting of an irrigated cotton field. Combined lidar images are used to form three-dimensional plumes. Plume dynamics and suspended aerosol concentrations are found. Dust plume dynamics varied with atmospheric stability. In particular, plume maximum height was significantly lower during stable conditions. Plume tracking indicated little change in plume cross-sectional area with height under unstable conditions and plume movement depended on wind speed and

  2. The Role of Cloud Contamination, Aerosol Layer Height and Aerosol Model in the Assessment of the OMI Near-UV Retrievals Over the Ocean

    NASA Technical Reports Server (NTRS)

    Gasso, Santiago; Torres, Omar

    2016-01-01

    Retrievals of aerosol optical depth (AOD) at 388 nm over the ocean from the Ozone Monitoring Instrument (OMI) two-channel near-UV algorithm (OMAERUV) have been compared with independent AOD measurements. The analysis was carried out over the open ocean (OMI and MODerate-resolution Imaging Spectrometer (MODIS) AOD comparisons) and over coastal and island sites (OMI and AERONET, the AErosol RObotic NETwork). Additionally, a research version of the retrieval algorithm (using MODIS and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) information as constraints) was utilized to evaluate the sensitivity of the retrieval to different assumed aerosol properties. Overall, the comparison resulted in differences (OMI minus independent measurements) within the expected levels of uncertainty for the OMI AOD retrievals (0.1 for AOD less than 0.3, 30% for AOD greater than 0.3). Using examples from case studies with outliers, the reasons that led to the observed differences were examined with specific purpose to determine whether they are related to instrument limitations (i.e., pixel size, calibration) or algorithm assumptions (such as aerosol shape, aerosol height). The analysis confirms that OMAERUV does an adequate job at rejecting cloudy scenes within the instrument's capabilities. There is a residual cloud contamination in OMI pixels with quality flag 0 (the best conditions for aerosol retrieval according to the algorithm), resulting in a bias towards high AODs in OMAERUV. This bias is more pronounced at low concentrations of absorbing aerosols (AOD 388 nm approximately less than 0.5). For higher aerosol loadings, the bias remains within OMI's AOD uncertainties. In pixels where OMAERUV assigned a dust aerosol model, a fraction of them (less than 20 %) had retrieved AODs significantly lower than AERONET and MODIS AODs. In a case study, a detailed examination of the aerosol height from CALIOP and the AODs from MODIS, along with sensitivity tests, was carried out by

  3. The role of cloud contamination, aerosol layer height and aerosol model in the assessment of the OMI near-UV retrievals over the ocean

    NASA Astrophysics Data System (ADS)

    Gassó, Santiago; Torres, Omar

    2016-07-01

    Retrievals of aerosol optical depth (AOD) at 388 nm over the ocean from the Ozone Monitoring Instrument (OMI) two-channel near-UV algorithm (OMAERUV) have been compared with independent AOD measurements. The analysis was carried out over the open ocean (OMI and MODerate-resolution Imaging Spectrometer (MODIS) AOD comparisons) and over coastal and island sites (OMI and AERONET, the AErosol RObotic NETwork). Additionally, a research version of the retrieval algorithm (using MODIS and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) information as constraints) was utilized to evaluate the sensitivity of the retrieval to different assumed aerosol properties. Overall, the comparison resulted in differences (OMI minus independent measurements) within the expected levels of uncertainty for the OMI AOD retrievals (0.1 for AOD < 0.3, 30 % for AOD > 0.3). Using examples from case studies with outliers, the reasons that led to the observed differences were examined with specific purpose to determine whether they are related to instrument limitations (i.e., pixel size, calibration) or algorithm assumptions (such as aerosol shape, aerosol height). The analysis confirms that OMAERUV does an adequate job at rejecting cloudy scenes within the instrument's capabilities. There is a residual cloud contamination in OMI pixels with quality flag 0 (the best conditions for aerosol retrieval according to the algorithm), resulting in a bias towards high AODs in OMAERUV. This bias is more pronounced at low concentrations of absorbing aerosols (AOD 388 nm ˜ < 0.5). For higher aerosol loadings, the bias remains within OMI's AOD uncertainties. In pixels where OMAERUV assigned a dust aerosol model, a fraction of them (< 20 %) had retrieved AODs significantly lower than AERONET and MODIS AODs. In a case study, a detailed examination of the aerosol height from CALIOP and the AODs from MODIS, along with sensitivity tests, was carried out by varying the different assumed parameters in the

  4. 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.

  5. Mechanism for production of secondary organic aerosols and their representation in atmospheric models. Final report

    SciTech Connect

    Seinfeld, J.H.; Flagan, R.C.

    1999-06-07

    This document contains the following: organic aerosol formation from the oxidation of biogenic hydrocarbons; gas/particle partitioning of semivolatile organic compounds to model inorganic, organic, and ambient smog aerosols; and representation of secondary organic aerosol formation in atmospheric models.

  6. 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

  7. Physicochemical properties of aerosols over the northeast Atlantic: Evidence for wind-speed-related submicron sea-salt aerosol production

    SciTech Connect

    O'Dowd, C.D.; Smith, M.H. )

    1993-01-20

    Physicochemical characteristics of submicron aerosol particles over the Northeast Atlantic (63[degrees]N, 8[degrees]W) during October/November 1989 have been examined using a thermal analytical technique and are classified according 10 air mass origin. Aerosol associated with anthropogenically influenced air masses contained typically 80% sulphate particles by number, the remainder being soot carbon and sea salt. For Arctic air masses the contribution of sulphate to the total aerosol was reduced to around 65%, due to low concentrations relative 10 sea salt which is dependent on wind speed. In situations with clean maritime air and high wind speeds, sulphate aerosol accounted for less than 25% of the total accumulation mode particles, the remainder consisting predominantly of sea salt. Arctic air masses and clean maritime air during periods of high winds were consistently acidic with inferred molar ratios of NH[sub 4][sup +]/SO[sub 4][sup =] near 0.2. The continental and modified maritime aerosol encountered was found to have molar ratios of about 0.8. Soot carbon was present in all air masses to a similar degree (5-13%). In clean air masses, submicron sea salt aerosol concentrations showed a strong exponential increase with wind speed (correlation coefficients cc [ge] 0.8), down to a dry particle radius of 0.05 [mu]m. Under these clean air' conditions and high winds the sea salt aerosol dominated all particle sizes for r > 0.05 [mu]m and accounted for approximately 75% of the total concentration, suggesting that under these conditions, sea salt aerosol would comprise the primary source cloud condensation nuclei (CCN) in stratiform clouds. 30 refs., 8 figs., 4 tabs.

  8. Development, Application, and Transition of Aerosol and Trace Gas Products Derived from Next-Generation Satellite Observations to Operations

    NASA Technical Reports Server (NTRS)

    Berndt, Emily; Naeger, Aaron; Zavodsky, Bradley; McGrath, Kevin; LaFontaine, Frank

    2016-01-01

    NASA Short-term Prediction Research and Transition (SPoRT) Center has a history of successfully transitioning unique observations and research capabilities to the operational weather community to improve short-term forecasts. SPoRTstrives to bridge the gap between research and operations by maintaining interactive partnerships with end users to develop products that match specific forecast challenges, provide training, and assess the products in the operational environment. This presentation focuses on recent product development, application, and transition of aerosol and trace gas products to operations for specific forecasting applications. Recent activities relating to the SPoRT ozone products, aerosol optical depth composite product, sulfur dioxide, and aerosol index products are discussed.

  9. The weather dependence of particle size distribution of indoor radioactive aerosol associated with radon decay products.

    PubMed

    Mostafa, A M A; Tamaki, K; Moriizumi, J; Yamazawa, H; Iida, T

    2011-07-01

    This study was performed to measure the activity size distribution of aerosol particles associated with short-lived radon decay products in indoor air at Nagoya University, Nagoya, Japan. The measurements were performed using a low pressure Andersen cascade impactor under variable meteorological conditions. The results showed that the greatest activity fraction was associated with aerosol particles in the accumulation size range (100-1000 nm) with a small fraction of nucleation mode (10-100 nm). Regarding the influence of the weather conditions, the decrease in the number of accumulation particles was observed clearly after rainfall without significant change in nucleation particles, which may be due to a washout process for the large particles.

  10. Speciation of water-soluble organic carbon compounds in boundary layer aerosols during the LBA/CLAIRE/SMOCC-2002 campaign

    NASA Astrophysics Data System (ADS)

    Claeys, M.; Pashynska, V.; Vermeylen, R.; Vas, G.; Cafmeyer, J.; Maenhaut, W.; Artaxo, P.

    2003-04-01

    The water-soluble, hygroscopic aerosol fraction is of climatic interest because of its role as cloud condensation nuclei (CCN) and the associated effects on cloud formation and cloud properties. As part of the LBA/CLAIRE/SMOCC experiment in Amazonia, September-November 2002, aerosol samples were collected using various types of samplers. The campaign spanned from the peak of the burning season, with high smoke concentrations, to fairly clean conditions in the early rainy season. Separate day and night samples were collected, and the collection time per sample varied from 12 hours in September to up to 48 hours in November. Fine (< 2.5 μm) and coarse (> 2.5 μm) aerosol size fractions were obtained using a Hi-Vol dichotomous sampler, and the samples were analysed for organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC) and various water-soluble organic carbon compounds. The latter compounds included the anhydrosugars, levoglucosan, mannosan, and galactosan, which are markers for wood combustion, the polyols, arabitol and mannitol, which originate from the natural forest environment, as well as the hydroxydicarboxylic acid, malic acid, which is a late product in the photochemistry of fatty acids and n-alkanes. Preliminary results including the mass concentrations of OC, EC, WSOC and the water-soluble organic compounds will be presented. By far the major water-soluble organic carbon compound in the fine size fraction was levoglucosan, showing concentrations in the range of 1-6 μg m-3 in the peak of the burning season (17-24 September).

  11. Single-Particle Measurements of Midlatitude Black Carbon and Light-Scattering Aerosols from the Boundary Layer to the Lower Stratosphere

    NASA Technical Reports Server (NTRS)

    Schwartz, J. P.; Gao, R. S.; Fahey, D. W.; Thomson, D. S.; Watts, L. A.; Wilson, J. C.; Reeves, J. M.; Darbeheshti, M.; Baumgardner, D. G.; Kok, G. L.; Chung, S. H.; Schulz, M.; Hendricks, J.; Lauer, A.; Kaercher, B.; Slowik, J. G.; Rosenlof, K. H.; Thompson, T. L.; Langford, A. O.; Loewenstein, M.; Aikin, K. C.

    2006-01-01

    A single-particle soot photometer (SP2) was flown on a NASA WB-57F high-altitude research aircraft in November 2004 from Houston, Texas. The SP2 uses laser-induced incandescence to detect individual black carbon (BC) particles in an air sample in the mass range of approx.3-300 fg (approx.0.15-0.7 microns volume equivalent diameter). Scattered light is used to size the remaining non-BC aerosols in the range of approx.0.17-0.7 microns diameter. We present profiles of both aerosol types from the boundary layer to the lower stratosphere from two midlatitude flights. Results for total aerosol amounts in the size range detected by the SP2 are in good agreement with typical particle spectrometer measurements in the same region. All ambient incandescing particles were identified as BC because their incandescence properties matched those of laboratory-generated BC aerosol. Approximately 40% of these BC particles showed evidence of internal mixing (e.g., coating). Throughout profiles between 5 and 18.7 km, BC particles were less than a few percent of total aerosol number, and black carbon aerosol (BCA) mass mixing ratio showed a constant gradient with altitude above 5 km. SP2 data was compared to results from the ECHAM4/MADE and LmDzT-INCA global aerosol models. The comparison will help resolve the important systematic differences in model aerosol processes that determine BCA loadings. Further intercomparisons of models and measurements as presented here will improve the accuracy of the radiative forcing contribution from BCA.

  12. Laser Remote Sensing From ISS: CATS Cloud and Aerosol Level 2 Data Products (Heritage Edition)

    NASA Technical Reports Server (NTRS)

    Rodier, Sharon; Vaughan, Mark; Palm, Steve; Jensen, Mike; Yorks, John; McGill, Matt; Trepte, Chip; Murray, Tim; Lee, Kam-Pui

    2015-01-01

    The Cloud-Aerosol Transport System (CATS) instrument was developed at NASA's Goddard Space Flight Center (GSFC) and deployed to the International Space Station (ISS) on 10 January 2015. CATS is mounted on the Japanese Experiment Module's Exposed Facility (JEM_EF) and will provide near-continuous, altitude-resolved measurements of clouds and aerosols in the Earth's atmosphere. The CATS ISS orbit path provides a unique opportunity to capture the full diurnal cycle of cloud and aerosol development and transport, allowing for studies that are not possible with the lidar aboard the CALIPSO platform, which flies in the sun-synchronous A-Train orbit." " One of the primary science objectives of CATS is to continue the CALIPSO aerosol and cloud profile data record to provide continuity of lidar climate observations during the transition from CALIPSO to EarthCARE. To accomplish this, the CATS project at NASA's Goddard Space Flight Center (GSFC) and the CALIPSO project at NASA's Langley Research Center (LaRC) are closely collaborating to develop and deliver a full suite of CALIPSO-like level 2 data products that will be produced using the newly acquired CATS level 1B data whenever CATS is operating in science modes 1. The CALIPSO mission is now well into its ninth year of on-orbit operations, and has developed a robust set of mature and well-validated science algorithms to retrieve the spatial and optical properties of clouds and aerosols from multi-wavelength lidar backscatter signals. By leveraging both new and existing NASA technical resources, this joint effort by the CATS and CALIPSO teams will deliver validated lidar data sets to the user community at the earliest possible opportunity. The science community will have access to two sets of CATS Level 2 data products. The "Operational" data products will be produced by the GSFC CATS team utilizing the new instrument capabilities (e.g., multiple FOVs and 1064 nm depolarization), while the "Heritage" data products created

  13. Wintertime aerosol characteristics over the Indo-Gangetic Plain (IGP): Impacts of local boundary layer processes and long-range transport

    NASA Astrophysics Data System (ADS)

    Nair, Vijayakumar S.; Moorthy, K. Krishna; Alappattu, Denny P.; Kunhikrishnan, P. K.; George, Susan; Nair, Prabha R.; Babu, S. Suresh; Abish, B.; Satheesh, S. K.; Tripathi, Sachchida Nand; Niranjan, K.; Madhavan, B. L.; Srikant, V.; Dutt, C. B. S.; Badarinath, K. V. S.; Reddy, R. Ramakrishna

    2007-07-01

    The Indo-Gangetic Plain (IGP) encompasses a vast area, (accounting for ˜21% of the land area of India), which is densely populated (accommodating ˜40% of the Indian population). Highly growing economy and population over this region results in a wide range of anthropogenic activities. A large number of thermal power plants (most of them coal fed) are clustered along this region. Despite its importance, detailed investigation of aerosols over this region is sparse. During an intense field campaign of winter 2004, extensive aerosol and atmospheric boundary layer measurements were made from three locations: Kharagpur (KGP), Allahabad (ALB), and Kanpur (KNP), within the IGP. These data are used (1) to understand the regional features of aerosols and BC over the IGP and their interdependencies, (2) to compare it with features at locations lying at far away from the IGP where the conditions are totally different, (3) to delineate the effects of mesoscale processes associated with changes in the local atmospheric boundary layer (ABL), (4) to investigate the effects of long-range transport or moving weather phenomena in modulating the aerosol properties as well as the ABL characteristics, and (5) to examine the changes as the season changes over to spring and summer. Our investigations have revealed very high concentrations of aerosols along the IGP, the average mass concentrations (MT) of total aerosols being in the range 260 to 300 μg m-3 and BC mass concentrations (MB) in the range 20 to 30 μg m-3 (both ˜5 to 8 times higher than the values observed at off-IGP stations) during December 2004. Despite, BC constituted about 10% to the total aerosol mass concentration, a value quite comparable to those observed elsewhere over India for this season. The dynamics of the local atmospheric boundary layer (ABL) as well as changes in local emissions strongly influence the diurnal variations of MT and MB, both being inversely correlated with the mixed layer height (Zi) and the

  14. New Global Deep Blue Aerosol Product over Land and Ocean from VIIRS, and Its comparisons with MODIS

    NASA Astrophysics Data System (ADS)

    Hsu, N. Y. C.; Bettenhausen, C.; Sayer, A. M.; Lee, J.; Tsay, S. C.; Carletta, N.

    2015-12-01

    The impacts of natural and anthropogenic sources of air pollution on climate and human health have continued to gain attention from the scientific community. In order to facilitate these effects, high quality consistent long-term global aerosol data records from satellites are essential. Several EOS-era instruments (e.g., SeaWiFS, MODIS, and MISR) are able to provide such information with a high degree of fidelity. However, with the aging MODIS sensors and the launch of the VIIRS instrument on Suomi NPP in late 2011, the continuation of long-term aerosol data records suitable for climate studies from MODIS to VIIRS is needed urgently. VIIRS was designed to have similar capabilities to MODIS, with similar visible/infrared spectral channels, and spatial/ temporal resolution. However, small but significant differences in several key channels used in aerosol retrievals between MODIS and VIIRS mean that significant effort is required to revise aerosol models and surface reflectance determination modules previously developed using MODIS data. In this study, we will show the global (land and ocean) distribution of aerosols from Version 1 of the VIIRS Deep Blue data set. The preliminary validation results of these new VIIRS Deep Blue aerosol products using data from AERONET sunphotometers over land and ocean will be discussed. We will also compare the monthly averaged Deep Blue aerosol optical thickness (AOT) from VIIRS with the MODIS C6 products to investigate if any systematic biases may exist between MODIS C6 and VIIRS AOT.

  15. Multiday production of condensing organic aerosol mass in urban and forest outflow

    NASA Astrophysics Data System (ADS)

    Lee-Taylor, J.; Hodzic, A.; Madronich, S.; Aumont, B.; Camredon, M.; Valorso, R.

    2014-07-01

    Secondary organic aerosol (SOA) production in air masses containing either anthropogenic or biogenic (terpene-dominated) emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for several days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (∼50%) and of shorter duration (1-2 days). The production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction products of both aromatics and alkanes. In particular we find large contributions from substituted maleic anhydrides and multi-substituted peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. The results imply that anthropogenic aerosol precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.

  16. Multiday production of condensing organic aerosol mass in urban and forest outflow

    NASA Astrophysics Data System (ADS)

    Lee-Taylor, J.; Hodzic, A.; Madronich, S.; Aumont, B.; Camredon, M.; Valorso, R.

    2015-01-01

    Secondary organic aerosol (SOA) production in air masses containing either anthropogenic or biogenic (terpene-dominated) emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for multiple days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (~50%) and of shorter duration (1-2 days). The multiday production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction products of both aromatics and alkanes, especially those with relatively low carbon numbers (C4-15). In particular we find large contributions from substituted maleic anhydrides and multi-substituted peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions and different vapor pressure schemes, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. The results imply that anthropogenic aerosol precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.

  17. Multiday production of condensing organic aerosol mass in urban and forest outflow

    DOE PAGES

    Lee-Taylor, J.; Hodzic, A.; Madronich, S.; Aumont, B.; Camredon, M.; Valorso, R.

    2014-07-03

    Secondary organic aerosol (SOA) production in air masses containing either anthropogenic or biogenic (terpene-dominated) emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for several days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (∼50%) and of shorter duration (1–2 days). The production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction products ofmore » both aromatics and alkanes. In particular we find large contributions from substituted maleic anhydrides and multi-substituted peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. The results imply that anthropogenic aerosol precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.« less

  18. Production, Organic Characterization, and Phase Transformations of Marine Particles Aerosolized from a Laboratory Mesocosm Phytoplankton Bioreactor

    NASA Astrophysics Data System (ADS)

    Alpert, P. A.; Knopf, D. A.; Aller, J. Y.; Radway, J.; Kilthau, W.

    2012-12-01

    Previous studies have shown that particles emitted from bubble bursting and wave breaking of ocean waters with high biological activity can contain sea salts associated with organic material, with smaller particles containing a larger mass fraction of organics than larger particles. This likely indicates a link between phytoplankton productivity in oceans and particulate organic material in marine air. Once aerosolized, particles with significant amount of organic material can affect cloud activation and formation of ice crystals, among other atmospheric processes, thus influencing climate. This is significant for clouds and climate particularly over nutrient rich polar seas, in which concentrations of biological organisms can reach up to 109 cells per ml during spring phytoplankton blooms. Here we present results of bubble bursting aerosol production from a seawater mesocosm containing artificial seawater, natural seawater and unialgal cultures of three representative phytoplankton species. These phytoplankton (Thalassiosira pseudonana, Emilianaia huxleyi, and Nannochloris atomus), possessed siliceous frustules, calcareous frustules and no frustules, respectively. Bubbles were generated employing recirculating impinging water jets or glass frits. Dry and humidified aerosol size distributions and bulk aerosol organic composition were measured as a function of phytoplankton growth, and chlorophyll composition and particulate and dissolved organic carbon in the water were determined. Finally, particles were collected on substrates for ice nucleation and water uptake experiments, their elemental compositions were determined using computer controlled scanning electron microscopy and energy dispersive analysis of X-rays (CCSEMEDAX), and their carbon speciation was determined using scanning transmission X-ray microscopy and near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). Particle size distributions exposed to dry and humidified air employing

  19. Gas-phase products and secondary aerosol yields from the ozonolysis of ten different terpenes

    NASA Astrophysics Data System (ADS)

    Lee, Anita; Goldstein, Allen H.; Keywood, Melita D.; Gao, Song; Varutbangkul, Varuntida; Bahreini, Roya; Ng, Nga L.; Flagan, Richard C.; Seinfeld, John H.

    2006-04-01

    The ozonolyses of six monoterpenes (α-pinene, β-pinene, 3-carene, terpinolene, α-terpinene, and myrcene), two sesquiterpenes (α-humulene and β-caryophyllene), and two oxygenated terpenes (methyl chavicol and linalool) were conducted individually in Teflon chambers to examine the gas-phase oxidation product and secondary organic aerosol (SOA) yields from these reactions. Particle size distribution and number concentration were monitored and allowed for the calculation of the SOA yield from each experiment, which ranged from 1 to 54%. A proton transfer reaction mass spectrometer (PTR-MS) was used to monitor the evolution of gas-phase products, identified by their mass to charge ratio (m/z). Several gas-phase oxidation products, formaldehyde, acetaldehyde, formic acid, acetone, acetic acid, and nopinone, were identified and calibrated. Aerosol yields, and the yields of these identified and calibrated oxidation products, as well as many higher m/z oxidation products observed with the PTR-MS, varied significantly between the different parent terpene compounds. The sum of measured oxidation products in the gas and particle phase ranged from 33 to 77% of the carbon in the reacted terpenes, suggesting there are still unmeasured products from these reactions. The observations of the higher molecular weight oxidation product ions provide evidence of previously unreported compounds and their temporal evolution in the smog chamber from multistep oxidation processes. Many of the observed ions, including m/z 111 and 113, have also been observed in ambient air above a Ponderosa pine forest canopy, and our results confirm they are consistent with products from terpene + O3 reactions. Many of these products are stable on the timescale of our experiments and can therefore be monitored in field campaigns as evidence for ozone oxidative chemistry.

  20. Indoor/outdoor radon decay products associated aerosol particle-size distributions and their relation to total number concentrations.

    PubMed

    Moriizumi, Jun; Yamada, Shinya; Xu, Yang; Matsuki, Satoru; Hirao, Shigekazu; Yamazawa, Hiromi

    2014-07-01

    The activity size distributions of indoor and outdoor radioactive aerosol associated with short-lived radon decay products were observed at Nagoya, Japan, for some periods from 2010 to 2012, following the indoor observation by Mostafa et al. [Mostafa, A. M. A., Tamaki, K., Moriizumi, J., Yamazawa, H. and Iida, T. The weather dependence of particle size distribution of indoor radioactive aerosol associated with radon decay products. Radiat. Prot. Dosim. 146: (1-3), 19-22 (2011)]. The tendency of smaller indoor activity median aerodynamic diameter (AMAD) after rainfalls showed in the previous study was not consistently obtained, while the consistent tendency of less indoor radioactive particles with diameters in the accumulation mode was observed again after rainfalls. The indoor aerosols showed activity size distributions similar to the outdoor ones. Non-radioactive aerosol particle concentrations measured with a laser particle counter suggested a somewhat liner relationship with AMAD.

  1. Gas phase emissions from cooking processes and their secondary aerosol production potential

    NASA Astrophysics Data System (ADS)

    Klein, Felix; Platt, Stephen; Bruns, Emily; Termime-roussel, Brice; Detournay, Anais; Mohr, Claudia; Crippa, Monica; Slowik, Jay; Marchand, Nicolas; Baltensperger, Urs; Prevot, Andre; El Haddad, Imad

    2014-05-01

    Long before the industrial evolution and the era of fossil fuels, high concentrations of aerosol particles were alluded to in heavily populated areas, including ancient Rome and medieval London. Recent radiocarbon measurements (14C) conducted in modern megacities came as a surprise: carbonaceous aerosol (mainly organic aerosol, OA), a predominant fraction of particulate matter (PM), remains overwhelmingly non-fossil despite extensive fossil fuel combustion. Such particles are directly emitted (primary OA, POA) or formed in-situ in the atmosphere (secondary OA, SOA) via photochemical reactions of volatile organic compounds (VOCs). Urban levels of non-fossil OA greatly exceed the levels measured in pristine environments strongly impacted by biogenic emissions, suggesting a contribution from unidentified anthropogenic non-fossil sources to urban OA. Positive matrix factorization (PMF) techniques applied to ambient aerosol mass spectrometer (AMS, Aerodyne) data identify primary cooking emissions (COA) as one of the main sources of primary non-fossil OA in major cities like London (Allan et al., 2010), New York (Sun et al., 2011) and Beijing (Huang et al., 2010). Cooking processes can also emit VOCs that can act as SOA precursors, potentially explaining in part the high levels of oxygenated OA (OOA) identified by the AMS in urban areas. However, at present, the chemical nature of these VOCs and their secondary aerosol production potential (SAPP) remain virtually unknown. The approach adopted here involves laboratory quantification of PM and VOC emission factors from the main primary COA emitting processes and their SAPP. Primary emissions from deep-fat frying, vegetable boiling, vegetable frying and meat cooking for different oils, meats and vegetables were analysed under controlled conditions after ~100 times dilution. A high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and a high resolution proton transfer time-of-flight mass spectrometer (PTR

  2. Aerosolized essential oils and individual natural product compounds as brown treesnake repellents.

    PubMed

    Clark, Larry; Shivik, John

    2002-08-01

    Chemical irritants useful as repellents for brown treesnakes (Boiga irregularis) were identified. Exposure to various compounds produced a range of intensities for locomotory behavior in snakes. Essential oils comprised of 10 g liter-1 solutions of cedarwood, cinnamon, sage, juniper berry, lavender and rosemary each were potent snake irritants. Brown treesnakes exposed to a 2-s burst of aerosol of these oils exhibited prolonged, violent undirected locomotory behavior. In contrast, exposure to a 10 g liter-1 concentration of ginger oil aerosol caused snakes to locomote, but in a deliberate, directed manner. We also tested specific compounds, all derivative of food and flavor ingredients. 10 g liter-1 solutions delivered as aerosols of m-anisaldehyde, trans-anethole, cineole, cinnamaldehyde, citral, ethyl phenylacetate, eugenol, geranyl acetate or methyl salicylate all acted as potent irritants for brown treesnakes. The individual ingredients were classified using cluster analysis into groups that promoted different levels of response by snakes. This study is the first to systematically investigate the irritant potential of natural products for snakes. These data will be useful in the development of practical pest management tools for snakes.

  3. Stratospheric sulfate aerosol in and near the Northern Hemisphere polar vortex - The morphology of the sulfate layer, multimodal size distributions, and the effect of denitrification

    NASA Technical Reports Server (NTRS)

    Wilson, J. G.; Stolzenburg, M. R.; Clark, W. E.; Loewenstein, M.; Ferry, G. V.; Chan, K. R.; Kelly, K. K.

    1992-01-01

    Measurements were made of stratospheric sulfate aerosols using a passive cavity aerosol spectrometer and a condensation nucleus counter on a NASA ER-2 aircraft in the Airborne Arctic Stratospheric Experiment of 1989. The problems of representative and accurate sampling and particle evaporation were explicitly addressed in the design of the inlets and reduction of the data. The measurements suggest that the sulfate aerosol is bimodal in the polar vortex above the mass mixing ratio maximum in the sulfate layer. It appears that a nuclei mode of small, newly formed particles exists in this region. A stronger case is made for a nuclei mode in the upper few kilometers of the troposphere and in the lower few kilometers of the stratosphere. This mode is probably a global phenomenon occurring in all seasons. Comparison of denitrified and nondenitrified air suggests that denitrification removes some of the larger sulfate particles.

  4. Multiday production of condensing organic aerosol mass in urban and forest outflow

    DOE PAGES

    Lee-Taylor, J.; Hodzic, A.; Madronich, S.; Aumont, B.; Camredon, M.; Valorso, R.

    2015-01-16

    Secondary organic aerosol (SOA) production in air masses containing either anthropogenic or biogenic (terpene-dominated) emissions is investigated using the explicit gas-phase chemical mechanism generator GECKO-A. Simulations show several-fold increases in SOA mass continuing for multiple days in the urban outflow, even as the initial air parcel is diluted into the regional atmosphere. The SOA mass increase in the forest outflow is more modest (~50%) and of shorter duration (1–2 days). The multiday production in the urban outflow stems from continuing oxidation of gas-phase precursors which persist in equilibrium with the particle phase, and can be attributed to multigenerational reaction productsmore » of both aromatics and alkanes, especially those with relatively low carbon numbers (C4–15). In particular we find large contributions from substituted maleic anhydrides and multi-substituted peroxide-bicyclic alkenes. The results show that the predicted production is a robust feature of our model even under changing atmospheric conditions and different vapor pressure schemes, and contradict the notion that SOA undergoes little mass production beyond a short initial formation period. The results imply that anthropogenic aerosol precursors could influence the chemical and radiative characteristics of the atmosphere over an extremely wide region, and that SOA measurements near precursor sources may routinely underestimate this influence.« less

  5. Secondary organic aerosol (trans)formation through aqueous phase guaiacol photonitration: chemical characterization of the products

    NASA Astrophysics Data System (ADS)

    Grgić, Irena; Kitanovski, Zoran; Kroflič, Ana; Čusak, Alen

    2014-05-01

    One of the largest primary sources of organic aerosol in the atmosphere is biomass burning (BB) (Laskin et al. 2009); in Europe its contribution to annual mean of PM10 is between 3 and 14 % (Maenhaut et al. 2012). During the process of wood burning many different products are formed via thermal degradation of wood lignin. Hardwood burning produces mainly syringol (2,6-dimetoxyphenol) derivatives, while softwood burning exclusively guaiacol (2-methoxyphenol) and its derivatives. Taking into account physical properties of methoxyphenols only, their concentrations in atmospheric waters might be underestimated. So, their aqueous phase reactions can be an additional source of SOA, especially in regions under significant influence of wood combustion. An important class of compounds formed during physical and chemical aging of the primary BBA in the atmosphere is nitrocatechols, known as strong absorbers of UV and Vis light (Claeys et al. 2012). Very recently, methyl-nitrocatechols were proposed as suitable markers for highly oxidized secondary BBA (Iinuma et al. 2010, Kitanovski et al. 2012). In the present work, the formation of SOA through aqueous phase photooxidation and nitration of guaiacol was examined. The key objective was to chemically characterize the main low-volatility products and further to check their possible presence in the urban atmospheric aerosols. The aqueous phase reactions were performed in a thermostated reactor under simulated sunlight in the presence of H2O2 and nitrite. Guaiacol reaction products were first concentrated by solid-phase extraction (SPE) and then subjected to semi-preparative liquid chromatography.The main product compounds were fractionated and isolated as pure solids and their structure was further elucidated by using nuclear magnetic resonance spectroscopy (1H, 13C and 2D NMR) and direct infusion negative ion electro-spray ionization tandem mass spectrometry (( )ESI-MS/MS). The main photonitration products of guaiacol (4

  6. Size distribution, composition and origin of the submicron aerosol in the marine boundary layer during the eastern Mediterranean "SUB-AERO" experiment

    NASA Astrophysics Data System (ADS)

    Eleftheriadis, K.; Colbeck, I.; Housiadas, C.; Lazaridis, M.; Mihalopoulos, N.; Mitsakou, C.; Smolík, J.; Ždímal, V.

    A period of intensive physical and chemical aerosol characterisation measurements was held over 5 days during July 2000 as part of the European SUB-AERO experiment.. Concurrent measurements were performed at the Finokalia remote coastal site on the island of Crete (Greece) and onboard the R/V " Aegaeon" which cruised in south part of the Aegean Sea northwards of Crete. The objective of the study was to investigate the spatial and temporal variability of microphysical parameters of the submicron aerosol and their dependence on airmass origin and chemical composition. The results reflect the submicron aerosol properties during airmass transport from the north including Europe and the Balkans and are in line with other studies on the aerosol properties of polluted continental air entering the marine boundary layer (MBL). Concentrations of submicron particulate matter (PM) mass were relatively higher at sea (20 μg m -3) compared to the coastal site (16 μg m -3). Concentrations of both organic carbon and sulphate, being the major water soluble component, were also higher at sea than at land. The high concentrations of ammonium and those of the water soluble organics, such as oxalate, can be attributed to emissions from mainland forest fires. The submicron aerosol number size distribution was unimodal with mobility mean diameters ( dg) ranging from 98 to 144 μm and standard deviations ( σg) from 1.56 to 1.9. Aerosol number concentrations at Finokalia were at least 50% lower especially when R/V Aegaeon sampled polluted air, but the modal parameters of the size distribution were very similar ( dg: 111-120, σg: 1.55-1.91). The surface MBL, under these conditions, was an aerosol rich environment where aerosol particles were transported both by the surface wind, advected from higher layers, chemically processed by interactions with gaseous precursors and physically altered by water vapour. The number to volume ratio for the submicrometer aerosol fraction reflected the

  7. Mass spectrometry of interfacial layers during fast aqueous aerosol/ozone gas reactions of atmospheric interest

    NASA Astrophysics Data System (ADS)

    Enami, S.; Vecitis, C. D.; Cheng, J.; Hoffmann, M. R.; Colussi, A. J.

    2008-04-01

    The oxidations of sulfite and iodide in the interfacial layers of aqueous microdroplets exposed to O 3(g) for 1 ms are investigated by online mass spectrometry of the electrostatically ejected anions. S(IV) oxidation losses in Na 2SO 3 microdroplets are proportional to [S(IV)] [O 3(g)] up to ˜90% conversion. I - is more abundant than HSO3- in the interfacial layers of equimolar (Na 2SO 3 + NaI) microdroplets and ˜3 times more reactive than HSO3- toward O 3(aq) in bulk solution, but it is converted withminimalloss to I3- and IO3- plus a persistent ISO3- intermediate. These observations reveal unanticipated interfacial gradients, reactivity patterns and transport phenomena that had not been taken into account in previous treatments of fast gas-liquid reactions.

  8. Quantifying VOC-Reaction Tracers, Ozone Production, and Continuing Aerosol Production Rates in Urban and Far-Downwind Atmospheres

    NASA Technical Reports Server (NTRS)

    Chatfield, Robert; Ren, X.; Brune, W.; Fried, A.; Schwab, J.

    2008-01-01

    We have found a surprisingly informative decomposition of the complex question of smoggy ozone production (basically, [HO2] in a more locally determined field of [NO]) in the process of linked investigations of modestly smoggy Eastern North America (by NASA aircraft, July 2004) and rather polluted Flushing, NYC (Queens College, July, 2001). In both rural and very polluted situations, we find that a simple contour graph parameterization of the local principal ozone production rate can be estimated using only the variables [NO] and j(sub rads) [HCHO]: Po(O3) = c (j(sub rads) [HCHO])(sup a) [HCHO](sup b). Here j(sub rads) is the photolysis of HCHO to radicals, presumably capturing many harder-UV photolytic processes and the principle ozone production is that due to HO2; mechanisms suggest that ozone production due to RO2 is closely correlated, often suggesting a limited range of different proportionality factors. The method immediately suggests a local interpretation for concepts of VOC limitation and NOx limitation. We believe that the product j(sub rads) [HCHO] guages the oxidation rate of observed VOC mixtures in a way that also provides [HO2] useful for the principle ozone production rate k [HO2] [NO], and indeed, all ozone chemical production. The success of the method suggests that dominant urban primary-HCHO sources may transition to secondary plume-HCHO sources in a convenient way. Are there other, simple, near-terminal oxidized VOC's which help guage ozone production and aerosol particle formation? Regarding particles, we report on, to the extent NASA Research resources allow, on appealing relationships between far-downwind (Atlantic PBL) HCHO and very fine aerosol (including sulfate. Since j(sub rads) [HCHO] provides a time-scale, we may understand distant-plume particle production in a more quantitative manner. Additionally we report on a statistical search in the nearer field for relationships between glyoxals (important near-terminal aromatic and isoprene

  9. Impact of Manaus City on the Amazon Green Ocean atmosphere: ozone production, precursor sensitivity and aerosol load

    NASA Astrophysics Data System (ADS)

    Kuhn, U.; Ganzeveld, L.; Thielmann, A.; Dindorf, T.; Schebeske, G.; Welling, M.; Sciare, J.; Roberts, G.; Meixner, F. X.; Kesselmeier, J.; Lelieveld, J.; Kolle, O.; Ciccioli, P.; Lloyd, J.; Trentmann, J.; Artaxo, P.; Andreae, M. O.

    2010-05-01

    As a contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia - Cooperative LBA Airborne Regional Experiment (LBA-CLAIRE-2001) field campaign in the heart of the Amazon Basin, we analyzed the temporal and spatial dynamics of the urban plume of Manaus City during the wet-to-dry season transition period in July 2001. During the flights, we performed vertical stacks of crosswind transects in the urban outflow downwind of Manaus City, measuring a comprehensive set of trace constituents including O3, NO, NO2, CO, VOC, CO2, and H2O. Aerosol loads were characterized by total aerosol number concentration (CN) and cloud condensation nuclei (CCN) concentrations, and light scattering properties. Measurements over pristine rainforest areas during the campaign showed low levels of pollution from biomass burning or industrial emissions, representative of wet season background conditions. The urban plume of Manaus City was found to be joined by plumes from power plants south of the city, all showing evidence of very strong photochemical ozone formation. One episode is discussed in detail, where a threefold increase in ozone mixing ratios in the atmospheric boundary layer occurred within a 100 km travel distance downwind of Manaus. Observation-based estimates of the ozone production rates in the plume reached 15 ppb h-1. Within the plume core, aerosol concentrations were strongly enhanced, with ΔCN/ΔCO ratios about one order of magnitude higher than observed in Amazon biomass burning plumes. ΔCN/ΔCO ratios tended to decrease with increasing transport time, indicative of a significant reduction in particle number by coagulation, and without substantial new particle nucleation occurring within the time/space observed. While in the background atmosphere a large fraction of the total particle number served as CCN (about 60-80% at 0.6% supersaturation), the CCN/CN ratios within the plume indicated that only a small fraction (16 ± 12%) of the plume particles were

  10. Impact of Manaus City on the Amazon Green Ocean atmosphere: ozone production, precursor sensitivity and aerosol load

    NASA Astrophysics Data System (ADS)

    Kuhn, U.; Ganzeveld, L.; Thielmann, A.; Dindorf, T.; Schebeske, G.; Welling, M.; Sciare, J.; Roberts, G.; Meixner, F. X.; Kesselmeier, J.; Lelieveld, J.; Kolle, O.; Ciccioli, P.; Lloyd, J.; Trentmann, J.; Artaxo, P.; Andreae, M. O.

    2010-10-01

    As a contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia - Cooperative LBA Airborne Regional Experiment (LBA-CLAIRE-2001) field campaign in the heart of the Amazon Basin, we analyzed the temporal and spatial dynamics of the urban plume of Manaus City during the wet-to-dry season transition period in July 2001. During the flights, we performed vertical stacks of crosswind transects in the urban outflow downwind of Manaus City, measuring a comprehensive set of trace constituents including O3, NO, NO2, CO, VOC, CO2, and H2O. Aerosol loads were characterized by concentrations of total aerosol number (CN) and cloud condensation nuclei (CCN), and by light scattering properties. Measurements over pristine rainforest areas during the campaign showed low levels of pollution from biomass burning or industrial emissions, representative of wet season background conditions. The urban plume of Manaus City was found to be joined by plumes from power plants south of the city, all showing evidence of very strong photochemical ozone formation. One episode is discussed in detail, where a threefold increase in ozone mixing ratios within the atmospheric boundary layer occurred within a 100 km travel distance downwind of Manaus. Observation-based estimates of the ozone production rates in the plume reached 15 ppb h-1. Within the plume core, aerosol concentrations were strongly enhanced, with ΔCN/ΔCO ratios about one order of magnitude higher than observed in Amazon biomass burning plumes. ΔCN/ΔCO ratios tended to decrease with increasing transport time, indicative of a significant reduction in particle number by coagulation, and without substantial new particle nucleation occurring within the time/space observed. While in the background atmosphere a large fraction of the total particle number served as CCN (about 60-80% at 0.6% supersaturation), the CCN/CN ratios within the plume indicated that only a small fraction (16±12%) of the plume particles were CCN

  11. Spatiotemporal fusion of multiple-satellite aerosol optical depth (AOD) products using Bayesian maximum entropy method

    NASA Astrophysics Data System (ADS)

    Tang, Qingxin; Bo, Yanchen; Zhu, Yuxin

    2016-04-01

    Merging multisensor aerosol optical depth (AOD) products is an effective way to produce more spatiotemporally complete and accurate AOD products. A spatiotemporal statistical data fusion framework based on a Bayesian maximum entropy (BME) method was developed for merging satellite AOD products in East Asia. The advantages of the presented merging framework are that it not only utilizes the spatiotemporal autocorrelations but also explicitly incorporates the uncertainties of the AOD products being merged. The satellite AOD products used for merging are the Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 5.1 Level-2 AOD products (MOD04_L2) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Deep Blue Level 2 AOD products (SWDB_L2). The results show that the average completeness of the merged AOD data is 95.2%,which is significantly superior to the completeness of MOD04_L2 (22.9%) and SWDB_L2 (20.2%). By comparing the merged AOD to the Aerosol Robotic Network AOD records, the results show that the correlation coefficient (0.75), root-mean-square error (0.29), and mean bias (0.068) of the merged AOD are close to those (the correlation coefficient (0.82), root-mean-square error (0.19), and mean bias (0.059)) of the MODIS AOD. In the regions where both MODIS and SeaWiFS have valid observations, the accuracy of the merged AOD is higher than those of MODIS and SeaWiFS AODs. Even in regions where both MODIS and SeaWiFS AODs are missing, the accuracy of the merged AOD is also close to the accuracy of the regions where both MODIS and SeaWiFS have valid observations.

  12. 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

    applications. The HSRL products are used to apportion AOT by type and vertical location in the column, and to characterize the frequency of cases where multiple types are present in the column. Resolving scenes with multiple types in the column is not possible with passive imaging radiometer and polarimeter measurements. The HSRL aerosol type also has higher resolution than the CALIPSO layer-wise product and provides insight into the performance of CALIPSO layer separation. Information about the vertical distribution of aerosol types is useful for estimating radiative forcing, understanding aerosol lifetime and transport, and assessing the predictions of transport models. CALIPSO has been a pathfinder, providing the first long-term global data set of aerosol vertical distribution. Based on our results, a future satellite lidar similar to CALIPSO, but with the addition of polarization sensitivity at 1064 nm and the HSRL technique at 532 nm, could provide a significant advance in characterizing the vertical distribution of aerosol.

  13. A novel approach to Lagrangian sampling of marine boundary layer cloud and aerosol in the northeast Pacific: case studies from CSET

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    The Cloud System Evolution in the Trades (CSET) field campaign took place during July/August 2015 with the purpose of characterizing the cloud, aerosol and thermodynamic properties of the northeast Pacific marine boundary layer. One major science goal of the campaign was to observe a Lagrangian transition from thin stratocumulus (Sc) upwind near California to trade cumulus (Cu) nearer to Hawaii. Cloud properties were observed from the NSF/NCAR Gulfstream V research plane (GV) using the HIAPER Cloud Radar (HCR) and the HIAPER Spectral Resolution Lidar (HSRL), among other instrumentation. Aircraft observations were complemented by a suite of satellite-derived products. To observe a the evolution of airmasses over the course of two days, upwind regions were sampled on an outbound flight to from Sacramento, CA, to Kona, HI. The sampled airmasses were then tracked using HYSPLIT trajectories based on GFS model forecasts, and the return flight to California was planned to intercept those airmasses, using satellite observation to track cloud evolution in the interim. This approach required that trajectories were reasonably stable up to 3 days prior to final sampling, and also that forecast trajectories were in agreement with post-flight analysis and visual cloud feature tracking. The extent to which this was realised, and hence the validity of this new approach to Lagrangian airmass observation, is assessed here. We also present results showing that a Sc-Cu airmass transition was consistently observed during the CSET study using measurements from research flights and satellite.

  14. 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.

  15. Aqueous secondary organic aerosol (SOA) production from the oxidation of phenols by triplet excited state organics

    NASA Astrophysics Data System (ADS)

    Smith, J.; Yu, L.; Zhang, Q.; Anastasio, C.

    2011-12-01

    Recent literature has shown that atmospheric condensed-phase chemistry can play a significant role in the evolution of organic aerosols, including the formation of secondary organic aerosol (SOA). SOA formation from the oxidation of volatile organic compounds (VOCs) in the aqueous phase has largely focused on oxidations involving the hydroxyl radical and other oxidants, such as photochemically created triplet excited states, have not been fully investigated. Phenolic compounds are one of the primary carbon emission classes from biomass and wood combustion and have significant water solubility. Once in the aqueous phase, phenolic compounds can react with the triplet excited states of non-phenolic aromatic carbonyls (NPCs), particle-bound organics that are also emitted in large quantities from wood combustion. The oxidation of phenolic species in the condensed phase by triplet excited states can result in the production of SOA. A main goal of this study was to investigate bulk solution reaction kinetics under atmospherically relevant conditions in order to ascertain how these reactions can impact aqueous-phase SOA production. In our experiments, we studied the reactions of five phenols (phenol, guaiacol, syringol, catechol, and resorcinol) with the triplet state of 3,4-dimethoxybenzaldehyde (34-DMB) during simulated solar radiation. We have characterized the impacts of pH, ionic strength and reactant concentrations on the reaction behavior of this system. In addition, we analyzed the SOA formed using high-resolution aerosol mass spectrometry, ion chromatography, and liquid chromatography-mass spectrometry to infer the reaction mechanisms. Our evidence suggests that under atmospherically relevant conditions, triplet excited states can be the dominant oxidant of phenolics and contribute significantly to the total SOA budget.

  16. Lidar measurements of boundary layers, aerosol scattering and clouds during project FIFE

    NASA Technical Reports Server (NTRS)

    Eloranta, Edwin W. (Principal Investigator)

    1995-01-01

    A detailed account of progress achieved under this grant funding is contained in five journal papers. The titles of these papers are: The calculation of area-averaged vertical profiles of the horizontal wind velocity using volume imaging lidar data; Volume imaging lidar observation of the convective structure surrounding the flight path of an instrumented aircraft; Convective boundary layer mean depths, cloud base altitudes, cloud top altitudes, cloud coverages, and cloud shadows obtained from Volume Imaging Lidar data; An accuracy analysis of the wind profiles calculated from Volume Imaging Lidar data; and Calculation of divergence and vertical motion from volume-imaging lidar data. Copies of these papers form the body of this report.

  17. 76 FR 60530 - Notice Pursuant to the National Cooperative Research and Production Act of 1993-Plastic Aerosol...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-29

    ... Antitrust Division Notice Pursuant to the National Cooperative Research and Production Act of 1993--Plastic...) of the National Cooperative Research and Production Act of 1993, 15 U.S.C. 4301 et seq. (``the Act''), Plastic Aerosol Research Group, L.L.C. (``PARG'') has filed written notifications simultaneously with...

  18. Aerosol Enhancements in the Upper Troposphere Over The Amazon Forest: Do Amazonian Clouds Produce Aerosols?

    NASA Astrophysics Data System (ADS)

    Andreae, M. O.; Afchine, A.; Albrecht, R. I.; Artaxo, P.; Borrmann, S.; Cecchini, M. A.; Costa, A.; Dollner, M.; Fütterer, D.; Järvinen, E.; Klimach, T.; Konemann, T.; Kraemer, M.; Krüger, M. L.; Machado, L.; Mertes, S.; Pöhlker, C.; Poeschl, U.; Sauer, D. N.; Schnaiter, M.; Schneider, J.; Schulz, C.; Spanu, A.; Walser, A.; Weinzierl, B.; Wendisch, M.

    2015-12-01

    The German-Brazilian cooperative aircraft campaign ACRIDICON-CHUVA (Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems) on the German research aircraft HALO took place over the Amazon Basin in September/October 2014, with the objective of studying tropical deep convective clouds over the Amazon rainforest and their interactions with trace gases, aerosol particles, and atmospheric radiation. The aircraft was equipped with about 30 remote sensing and in-situ instruments for meteorological, trace gas, aerosol, cloud, precipitation, and solar radiation measurements. Fourteen research flights were conducted during this campaign. Observations during ACRIDICON-CHUVA showed high aerosol concentrations in the upper troposphere (UT) over the Amazon Basin, with concentrations after normalization to standard conditions often exceeding those in the boundary layer (BL). This behavior was consistent between several aerosol metrics, including condensation nuclei (CN), cloud condensation nuclei (CCN), and chemical species mass concentrations. These UT aerosols were different in their composition and size distribution from the aerosol in the BL, making convective transport of particles unlikely as a source. The regions in the immediate outflow of deep convective clouds were found to be depleted in aerosol particles, whereas enhanced aerosol number and mass concentrations were found in UT regions that had experienced outflow from deep convection in the preceding 24-48 hours. This suggests that aerosol production takes place in the UT based on volatile and condensable material brought up by deep convection. Subsequently, downward mixing and transport of upper tropospheric aerosol may be a source of particles to the BL, where they increase in size by the condensation of biogenic volatile organic carbon (BVOC) oxidation products. This may be an important source of aerosol particles in the Amazonian BL, where aerosol nucleation and new

  19. Modeling the feedback between aerosol and meteorological variables in the atmospheric boundary layer during a severe fog-haze event over the North China Plain

    NASA Astrophysics Data System (ADS)

    Gao, Yi; Zhang, Meigen; Liu, Zirui; Wang, Lili; Wang, Pucai; Xia, Xiangao; Tao, Minghui; Zhu, Lingyun

    2016-04-01

    The feedback between aerosol and meteorological variables in the atmospheric boundary layer over the North China Plain (NCP) is analyzed by conducting numerical experiments with and without the aerosol direct and indirect effects via a coupled meteorology and aerosol/chemistry model(WRF-Chem). The numerical experiments are performed for the period of 2-26 January 2013, during which a severe fog-haze event (10-15 January 2013) occurred, with the simulated maximum hourly surface PM2.5 concentration of ~600 μg m-3, minimum atmospheric visibility of ~0.3 km, and 10-100 hours of simulated hourly surface PM2.5 concentration above 300 μg m-3 over NCP. A comparison of model results with aerosol feedback against observations indicates that the model can reproduce the spatial and temporal characteristics of temperature, relative humidity (RH), wind, surface PM2.5 concentration, atmospheric visibility, and aerosol optical depth reasonably well. Analysis of model results with and without aerosol feedback shows that during the fog-haze event aerosols lead to a significant negative radiative forcing of ~20 to ~140 W m-2 at the surface and a large positive radiative forcing of 20-120 W m-2 in the atmosphere and induce significant changes in meteorological variables with maximum changes during 09:00-18:00 local time (LT) over urban Beijing and Tianjin and south Hebei: the temperature decreases by 0.8-2.8 °C at the surface and increases by 0.1-0.5 °C at around 925 hPa, while RH increases by about 4-12% at the surface and decreases by 1-6% at around 925 hPa. As a result, the aerosol-induced equivalent potential temperature profile change shows that the atmosphere is much more stable and thus the surface wind speed decreases by up to 0.3 m s-1 (10 %) and the atmosphere boundary layer height decreases by 40-200 m (5-30 %) during the daytime of this severe fog-haze event. Owing to this more stable atmosphere during 09:00-18:00, 10-15 January, compared to the surface PM2

  20. Modeling the feedback between aerosol and meteorological variables in the atmospheric boundary layer during a severe fog-haze event over the North China Plain

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Zhang, M.; Liu, Z.; Wang, L.; Wang, P.; Xia, X.; Tao, M.

    2015-01-01

    The feedback between aerosol and meteorological variables in the atmospheric boundary layer over the North China Plain is analyzed by conducting numerical experiments with and without the aerosol direct and indirect effects via a coupled meteorology and aerosol/chemistry model (WRF-Chem). The numerical experiments are performed for the period 2-26 January 2013, during which a severe fog-haze event (10-15 January 2013) occurred. Comparison of the model results with aerosol feedback against observations indicates that the model can reproduce the spatial and temporal characteristics of temperature, relative humidity (RH), wind, surface PM2.5 concentration, atmospheric visibility, and aerosol optical depth. Comparison of modeling results in the presence and absence of aerosol feedback during the fog-haze event shows that aerosols lead to a significant negative radiative forcing of -20 to -140 W m-2 at the surface and a large positive radiative forcing of 20-120 W m-2 in the atmosphere and induce significant changes in meteorological variables of which the maximum changes occur during 09:00-18:00 LT over urban Beijing and Tianjin, and south Hebei Province: the temperature decreases by 0.8-2.8 °C at the surface and increases by 0.1-0.5 °C at around 925 hPa while the RH increases by about 4-12% at the surface and decreases by 1-6% at around 925 hPa. As a result, the aerosol-induced equivalent potential temperature profile change shows that the atmosphere is much more stable and thus the surface wind speed decreases by up to 0.3 m s-1 (10%) and the atmosphere boundary layer height decreases by 40-200 m (5-30%) during the daytime of this severe fog-haze event. Owing to this more stable atmosphere, during 09:00-18:00, 10-15 January, compared to the surface PM2.5 concentration from the model results without aerosol feedback, the average surface PM2.5 concentration increases by 10-50 μg m-3 (2-30%) over Beijing, Tianjin, and south Hebei province and the maximum increase of

  1. Modeling the feedback between aerosol and meteorological variables in the atmospheric boundary layer during a severe fog-haze event over the North China Plain

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Zhang, M.; Liu, Z.; Wang, L.; Wang, P.; Xia, X.; Tao, M.; Zhu, L.

    2015-04-01

    The feedback between aerosol and meteorological variables in the atmospheric boundary layer over the North China Plain (NCP) is analyzed by conducting numerical experiments with and without the aerosol direct and indirect effects via a coupled meteorology and aerosol/chemistry model (WRF-Chem). The numerical experiments are performed for the period of 2-26 January 2013, during which a severe fog-haze event (10-15 January 2013) occurred, with the simulated maximum hourly surface PM2.5 concentration of ~600 ug m-3, minimum atmospheric visibility of ~0.3 km, and 10-100 hours of simulated hourly surface PM2.5 concentration above 300 ug m-3 over NCP. A comparison of model results with aerosol feedback against observations indicates that the model can reproduce the spatial and temporal characteristics of temperature, relative humidity (RH), wind, surface PM2.5 concentration, atmospheric visibility, and aerosol optical depth reasonably well. Analysis of model results with and without aerosol feedback shows that during the fog-haze event aerosols lead to a significant negative radiative forcing of -20 to -140 W m-2 at the surface and a large positive radiative forcing of 20-120 W m-2 in the atmosphere and induce significant changes in meteorological variables with maximum changes during 09:00-18:00 local time (LT) over urban Beijing and Tianjin and south Hebei: the temperature decreases by 0.8-2.8 °C at the surface and increases by 0.1-0.5 °C at around 925 hPa, while RH increases by about 4-12% at the surface and decreases by 1-6% at around 925 hPa. As a result, the aerosol-induced equivalent potential temperature profile change shows that the atmosphere is much more stable and thus the surface wind speed decreases by up to 0.3 m s-1 (10%) and the atmosphere boundary layer height decreases by 40-200 m (5-30%) during the daytime of this severe fog-haze event. Owing to this more stable atmosphere during 09:00-18:00, 10-15~January, compared to the surface PM2

  2. The optical, physical and chemical properties of the products of glyoxal uptake on ammonium sulfate seed aerosols

    NASA Astrophysics Data System (ADS)

    Trainic, M.; Abo Riziq, A.; Lavi, A.; Flores, J. M.; Rudich, Y.

    2011-09-01

    The heterogeneous reaction between gas phase glyoxal and ammonium sulfate (AS) aerosols, a proxy for inorganic atmospheric aerosol, was studied in terms of the dependence of the optical, physical and chemical properties of the product aerosols on initial particle size and ambient relative humidity (RH). Our experiments imitate an atmospheric scenario of a dry particle hydration at ambient RH conditions in the presence of glyoxal gas followed by efflorescence due to decrease of the ambient RH. The reactions were studied under different RH conditions, starting from dry conditions (~20% RH) and up to 90% RH, covering conditions prevalent in many atmospheric environments, and followed by consequent drying of the reacted particles before their analysis by the aerosol mass spectrometer (AMS), cavity ring down (CRD) and scanning mobility particle sizer (SMPS) systems. At λ = 355 nm, the reacted aerosols demonstrate a substantial growth in optical extinction cross section, as well as in mobility diameter under a broad range of RH values (35-90%). The ratio of the product aerosol to seed aerosol geometric cross section reached up to ~3.5, and the optical extinction cross-section up to ~250. The reactions show a trend of increasing physical and optical growth with decreasing seed aerosol size, from 100 nm to 300 nm, as well as with decreasing RH values from 90% to ~40%. Optically inactive aerosols, at the limit of the Mie range (100 nm diameter) become optically active as they grow due to the reaction. AMS analyses of the reaction of 300 nm AS at RH values of 50%, 75% and 90% show that the main products of the reaction are glyoxal oligomers, formed by acetal formation in the presence of AS. In addition, imidazole formation, which is a minor channel, is observed for all reactions, yielding a product which absorbs at λ = 290 nm, with possible implications on the radiative properties of the product aerosols. The ratio of absorbing substances (C-N compounds, including

  3. 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.

  4. Estimating the direct radiative effect of absorbing aerosols overlying marine boundary layer clouds in the southeast Atlantic using MODIS and CALIOP

    NASA Astrophysics Data System (ADS)

    Meyer, Kerry; Platnick, Steven; Oreopoulos, Lazaros; Lee, Dongmin

    2013-05-01

    aerosols such as smoke strongly absorb solar radiation, particularly at ultraviolet and visible/near-infrared (VIS/NIR) wavelengths, and their presence above clouds can have considerable implications. It has been previously shown that they have a positive (i.e., warming) direct aerosol radiative effect (DARE) when overlying bright clouds. Additionally, they can cause biased passive instrument satellite retrievals in techniques that rely on VIS/NIR wavelengths for inferring the cloud optical thickness (COT) and effective radius (re) of underlying clouds, which can in turn yield biased above-cloud DARE estimates. Here we investigate Moderate Resolution Imaging Spectroradiometer (MODIS) cloud optical property retrieval biases due to overlying absorbing aerosols observed by Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and examine the impact of these biases on above-cloud DARE estimates. The investigation focuses on a region in the southeast Atlantic Ocean during August and September (2006-2011), where smoke from biomass burning in southern Africa overlies persistent marine boundary layer stratocumulus clouds. Adjusting for above-cloud aerosol attenuation yields increases in the regional mean liquid COT (averaged over all ocean-only liquid clouds) by roughly 6%; mean re increases by roughly 2.6%, almost exclusively due to the COT adjustment in the non-orthogonal retrieval space. It is found that these two biases lead to an underestimate of DARE. For liquid cloud Aqua MODIS pixels with CALIOP-observed above-cloud smoke, the regional mean above-cloud radiative forcing efficiency (DARE per unit aerosol optical depth (AOD)) at time of observation (near local noon for Aqua overpass) increases from 50.9Wm-2AOD-1 to 65.1Wm-2AOD-1 when using bias-adjusted instead of nonadjusted MODIS cloud retrievals.

  5. Estimating the Direct Radiative Effect of Absorbing Aerosols Overlying Marine Boundary Layer Clouds in the Southeast Atlantic Using MODIS and CALIOP

    NASA Technical Reports Server (NTRS)

    Meyer, Kerry; Platnick, Steven; Oreopoulos, Lazaros; Lee, Dongmin

    2013-01-01

    Absorbing aerosols such as smoke strongly absorb solar radiation, particularly at ultraviolet and visible/near-infrared (VIS/NIR) wavelengths, and their presence above clouds can have considerable implications. It has been previously shown that they have a positive (i.e., warming) direct aerosol radiative effect (DARE) when overlying bright clouds. Additionally, they can cause biased passive instrument satellite retrievals in techniques that rely on VIS/NIR wavelengths for inferring the cloud optical thickness (COT) and effective radius (re) of underlying clouds, which can in turn yield biased above-cloud DARE estimates. Here we investigate Moderate Resolution Imaging Spectroradiometer (MODIS) cloud optical property retrieval biases due to overlying absorbing aerosols observed by Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and examine the impact of these biases on above-cloud DARE estimates. The investigation focuses on a region in the southeast Atlantic Ocean during August and September (2006-2011), where smoke from biomass burning in southern Africa overlies persistent marine boundary layer stratocumulus clouds. Adjusting for above-cloud aerosol attenuation yields increases in the regional mean liquid COT (averaged over all ocean-only liquid clouds) by roughly 6%; mean re increases by roughly 2.6%, almost exclusively due to the COT adjustment in the non-orthogonal retrieval space. It is found that these two biases lead to an underestimate of DARE. For liquid cloud Aqua MODIS pixels with CALIOP-observed above-cloud smoke, the regional mean above-cloud radiative forcing efficiency (DARE per unit aerosol optical depth (AOD)) at time of observation (near local noon for Aqua overpass) increases from 50.9Wm(sup-2)AOD(sup-1) to 65.1Wm(sup-2)AOD(sup -1) when using bias-adjusted instead of nonadjusted MODIS cloud retrievals.

  6. Effect of Wildfire Aerosols on NO2 Photolysis and Ozone Production at the Mt. Bachelor Observatory

    NASA Astrophysics Data System (ADS)

    Baylon, P.; Jaffe, D. A.; Hall, S. R.; Ullmann, K.; Lefer, B. L.

    2015-12-01

    In this study, we have two goals: to quantify the effect of biomass burning aerosols on jNO2 photolysis and to look at O3 formation in biomass burning plumes as it relates to jNO2 photolysis. Wildfire plumes were observed during the summer of 2015 at the Mt. Bachelor Observatory, a high-elevation (2.8 km a.s.l.) mountaintop site located in central Oregon. These plumes were identified using the following criteria: (1) 5-minute ambient aerosol scattering σsp ≥ 20 Mm-1 for at least two hours, (2) 5-minute CO ≥ 150 ppbv for at least two hours, (3) strong correlation (r2 ≥ 0.70) between σsp and CO, and (4) consistent air mass back trajectories indicating transport over known fire locations. We measure nitrogen oxides using a chemiluminescence detector and jNO2 photolysis using a diode array actinic flux spectroradiometer. We also measure O3 using two techniques: (a) UV method with a cavity ring-down spectrometer and (b) chemiluminescence method with a custom-made instrument. We compare fire event observations between these two procedures to prove consistency. Based on these measurements, we quantify a lower bound for the HO2 and RO2 radical concentrations in wildfire plumes. We then look at plume and non-plume data and examine deviations from the photostationary state. Finally, we use the TUV model v5.2 to simulate clear-sky conditions and therefore quantify the reduction/enhancement in jNO2 values and O3 production due to wildfire aerosols. This gives us insight into the photochemical environment in biomass burning plumes, which until now, remains poorly understood.

  7. Formation and characterization of fission-product aerosols under postulated HTGR accident conditions

    SciTech Connect

    Tang, I.N.; Munkelwitz, H.R.

    1982-07-01

    The paper presents the results of an experimental investigation on the formation mechanism and physical characterization of simulated nuclear aerosols that could likely be released during an HTGR core heat-up accident. Experiments were carried out in a high-temperature flow system consisting essentially of an inductively heated release source, a vapor deposition tube, and a filter assembly for collecting particulate matter. Simulated fission products Sr and Ba as oxides are separately impregnated in H451 graphite wafers and released at elevated temperatures into a dry helium flow. In the presence of graphite, the oxides are quantitatively reduced to metals, which subsequently vaporize at temperatures much lower than required for the oxides alone to vaporize in the absence of graphite. A substantial fraction of the released material is associated with particulate matter, which is collected on filters located downstream at ambient temperature. The release and transport of simulated fission product Ag as metal are also investigated.

  8. A Comparison of Parameterizations of Secondary Organic Aerosol Production: Global Budget and Spatiotemporal Variability

    NASA Astrophysics Data System (ADS)

    Liu, J.; Chen, Z.; Horowitz, L. W.; Carlton, A. M. G.; Fan, S.; Cheng, Y.; Ervens, B.; Fu, T. M.; He, C.; Tao, S.

    2014-12-01

    Secondary organic aerosols (SOA) have a profound influence on air quality and climate, but large uncertainties exist in modeling SOA on the global scale. In this study, five SOA parameterization schemes, including a two-product model (TPM), volatility basis-set (VBS) and three cloud SOA schemes (Ervens et al. (2008, 2014), Fu et al. (2008) , and He et al. (2013)), are implemented into the global chemical transport model (MOZART-4). For each scheme, model simulations are conducted with identical boundary and initial conditions. The VBS scheme produces the highest global annual SOA production (close to 35 Tg·y-1), followed by three cloud schemes (26-30 Tg·y-1) and TPM (23 Tg·y-1). Though sharing a similar partitioning theory to the TPM scheme, the VBS approach simulates the chemical aging of multiple generations of VOCs oxidation products, resulting in a much larger SOA source, particularly from aromatic species, over Europe, the Middle East and Eastern America. The formation of SOA in VBS, which represents the net partitioning of semi-volatile organic compounds from vapor to condensed phase, is highly sensitivity to the aging and wet removal processes of vapor-phase organic compounds. The production of SOA from cloud processes (SOAcld) is constrained by the coincidence of liquid cloud water and water-soluble organic compounds. Therefore, all cloud schemes resolve a fairly similar spatial pattern over the tropical and the mid-latitude continents. The spatiotemporal diversity among SOA parameterizations is largely driven by differences in precursor inputs. Therefore, a deeper understanding of the evolution, wet removal, and phase partitioning of semi-volatile organic compounds, particularly above remote land and oceanic areas, is critical to better constrain the global-scale distribution and related climate forcing of secondary organic aerosols.

  9. Spatial and Temporal Characteristics of Aerosols from Collection 6 Aqua and Terra MODIS e-Deep Blue Products

    NASA Astrophysics Data System (ADS)

    Bettenhausen, C.; Hsu, N. Y. C.; Sayer, A. M.; Lee, J.; Carletta, N.

    2015-12-01

    Aerosols continue to attract a significant amount of attention from researchers worldwide due to their extensive effects on Earth's climate, ecology, public health, and even energy production. In order to truly understand these effects, a long, stable, and well-calibrated data record is required. Since 2000 and 2002, the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard the Terra and Aqua satellites together with the e-Deep Blue aerosol retrieval algorithm have been providing such a data record. After a multi-year development effort, the production of both Aqua and Terra MODIS Collection 6 (C6) atmosphere products successfully completed earlier this year and the data was released to the public shortly thereafter. The C6 Deep Blue products (now enhanced Deep Blue or e-Deep Blue) have been significantly improved over the previous Collection 5.1 version. In this poster we provide an overview of the latest C6 e-Deep Blue products and the improvements implemented since the previous collection including coverage over dark surfaces and updates to the Terra calibration. Validation results utilizing Aerosol Robotic Network (AERONET) data are also summarized. We then use the C6 e-Deep Blue products from both Aqua and Terra to explore the spatial characteristics in addition to the seasonal and inter-annual variability of aerosols on both regional and global scales. We also use this as an opportunity to compare these results and investigate any differences found between the two instruments.

  10. The Effects of Aerosols on Cloud Microphysics in Caribbean Islands and Implications for Rain Production

    NASA Astrophysics Data System (ADS)

    Gonzalez, J. E.; Comarazamy, D.

    2011-12-01

    A cloud-resolving regional atmospheric model driven with atmospheric particle (AP) observations performed at the Arecibo Observatory was used to investigate the possible effects of different AP concentrations on cloud formation and rain development over the Caribbean Island of Puerto Rico. The cloud microphysics module of the atmospheric model includes cloud condensation nuclei activation (CCN), and two aerosol modes (CCN/GCCN) and cloud drop categories. First, the modeling system was tested to satisfactorily simulate precipitation in the region of study. Then, a set of idealized simulations showed that cloud droplet production is significantly larger in polluted air than in clear skies and that rainwater in polluted air is less than that in clear air. This occurs because more droplets are competing for the available atmospheric water vapor, they will not reach the necessary radius to fall within the cloud, and therefore growth by collision and coalescence is subdued. Following these results, the modeling system (regional atmospheric model + CCN/GCCN activation + in-situ aerosol observations) was then used to investigate the role of aerosols in originating and controlling the Caribbean mid-summer drought (MSD). The annual precipitation pattern in the Caribbean basin shows a distinct bimodal behavior, where the first mode is called the Early Rainfall Season (ERS, April-July), and the second mode the Late Rainfall Season (LRS, August-November). The brief, relatively low-precipitation, period in July is usually referred to as the MSD. It has been hypothesized that increases in aerosols due to the passing of Saharan Dust across the Caribbean in the summer months may result in the observed precipitation pattern. Multiple regression analysis was carried-out to determine if the ITCZ, NAO index, vertical wind shear (VWS), and different AP concentrations correlate with the Caribbean MSD. It is shown that VWS and AP have an important contribution to rainfall variability

  11. Irreversible Entropy Production in Two-Phase Mixing Layers

    NASA Technical Reports Server (NTRS)

    Okongo, Nora

    2003-01-01

    This report presents a study of dissipation (irreversible production of entropy) in three-dimensional, temporal mixing layers laden with evaporating liquid drops. The purpose of the study is to examine the effects of evaporating drops on the development of turbulent features in flows. Direct numerical simulations were performed to analyze transitional states of three mixing layers: one without drops, and two that included drops at different initial mass loadings. Without drops, the dissipation is essentially due to viscous effects. It was found that in the presence of drops, the largest contribution to dissipation was made by heating and evaporation of the drops, and that at large length scales, this contribution is positive (signifying that the drops reduce turbulence), while at small scales, this contribution is negative (the drops increase turbulence). The second largest contribution to dissipation was found to be associated with the chemical potential, which leads to an increase in turbulence at large scales and a decrease in turbulence at small scales. The next smaller contribution was found to be that of viscosity. The fact that viscosity effects are only third in order of magnitude in the dissipation is in sharp contrast to the situation for the mixing layer without the drops. The next smaller contribution - that of the drag and momentum of the vapor from the drops - was found to be negative at lower mass loading but to become positive at higher mass loading.

  12. Simulated consumer exposure to propellant HCFC 22 (chlorodifluoromethane) in aerosol personal products.

    PubMed

    Hartop, P J; Adams, M G

    1989-02-01

    Summary The potential human exposure to the aerosol propellant HCFC 22 (chlorodifluoromethane) arising from its use in personal products has been assessed. HCFC 22 concentrations were measured in the 'breathing zone' of an experimental manikin and an 'accompanying child' designed to simulate human use of hairsprays, body sprays and antiperspirants in a closed room. Results were expressed as the 10-min time-weighted average concentration in the air (TWA 10) and as the peak concentration in the 'breathing zone' of the 'user'. Following a 10-s use of hairspray containing approximately 20-40% HCFC 22, TWA10 values for an adult user and child were 64-116 ppm and 44-100 ppm, respectively. Use of an aerosol body spray containing 20-65% HCFC 22 for 5-20 s gave rise to TWA10 values of 32-411 ppm for an adult user and 20-395 ppm for a child. A 4-s use of an antiperspirant containing approximately 20-40% HCFC 22 sprayed at a distance of 10-30 cm from the breathing zone of the adult user generated TWA 10 values in the range of 14-34 ppm for both the adult user and child. Opening the door of the room prior to hairspray and antiperspirant spraying slightly reduced these TWA 10 values. The peak values recorded in these studies for the adult user were 208 ppm for hairspray, 1415 ppm for body sprays and 82 ppm for antiperspirants.

  13. Chemical sinks of organic aerosol: kinetics and products of the heterogeneous oxidation of erythritol and levoglucosan.

    PubMed

    Kessler, Sean H; Smith, Jared D; Che, Dung L; Worsnop, Douglas R; Wilson, Kevin R; Kroll, Jesse H

    2010-09-15

    The heterogeneous oxidation of pure erythritol (C(4)H(10)O(4)) and levoglucosan (C(6)H(10)O(5)) particles was studied in order to evaluate the effects of atmospheric aging on the mass and chemical composition of atmospheric organic aerosol. In contrast to what is generally observed for the heterogeneous oxidation of reduced organics, substantial volatilization is observed in both systems. However, the ratio of the decrease in particle mass to the decrease in the concentration of the parent species is about three times higher for erythritol than for levoglucosan, indicating that details of chemical structure (such as carbon number, cyclic moieties, and oxygen-containing functional groups) play a governing role in the importance of volatilization reactions. The kinetics of the reaction indicate that while both compounds react at approximately the same rate, reactions of their oxidation products appear to be slowed substantially. Estimates of volatilities of organic species based on elemental composition measurements suggest that the heterogeneous oxidation of oxygenated organics may be an important loss mechanism of organic aerosol.

  14. Are anthropogenic aerosols affecting rainfall?

    NASA Astrophysics Data System (ADS)

    Junkermann, Wolfgang; Hacker, Jorg

    2013-04-01

    Modification of cloud microphysics by anthropogenic aerosols is well known since several decades. Whether the underlying processes leads to changes in precipitation is by far less confirmed. Several different factors affect the production of rain in a way that a causality between increasing aerosol load in the atmosphere and a change of annual rainfall is very difficult to confirm. What would be expected as an effect of additional cloud condensation nuclei is a shift in the spatial and temporal rainfall distribution towards a lower number of days with low rain intensity and more frequent or more vigorous single events. In fact such a shift has been observed in several locations worldwide and has been suggested to be caused by increasing aerosol load, however, without further specification of the nature and number of the aerosols involved. Measurements of aerosols which might be important for cloud properties are extremely sparse and no long term monitoring data sets are available up to now. The problem of missing long term aerosol data that could be compared to available long term meteorological data sets can possibly be resolved in certain areas where well characterized large anthropogenic aerosol sources were installed in otherwise pristine areas without significant changes in land use over several decades. We investigated aerosol sources and current aerosol number, size and spatial distributions with airborne measurements in the planetary boundary layer over two regions in Australia that are reported to suffer from extensive drought despite the fact that local to regional scale water vapor in the atmosphere is slowly and constantly increasing. Such an increase of the total water in the planetary boundary layer would imply also an increase in annual precipitation as observed in many other locations elsewhere. The observed decline of rainfall in these areas thus requires a local to regional scale physical process modifying cloud properties in a way that rain

  15. Using the OMI aerosol index and absorption aerosol optical depth to evaluate the NASA MERRA Aerosol Reanalysis

    NASA Astrophysics Data System (ADS)

    Buchard, V.; da Silva, A. M.; Colarco, P. R.; Darmenov, A.; Randles, C. A.; Govindaraju, R.; Torres, O.; Campbell, J.; Spurr, R.

    2015-05-01

    A radiative transfer interface has been developed to simulate the UV aerosol index (AI) from the NASA Goddard Earth Observing System version 5 (GEOS-5) aerosol assimilated fields. The purpose of this work is to use the AI and aerosol absorption optical depth (AAOD) derived from the Ozone Monitoring Instrument (OMI) measurements as independent validation for the Modern Era Retrospective analysis for Research and Applications Aerosol Reanalysis (MERRAero). MERRAero is based on a version of the GEOS-5 model that is radiatively coupled to the Goddard Chemistry, Aerosol, Radiation, and Transport (GOCART) aerosol module and includes assimilation of aerosol optical depth (AOD) from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. Since AI is dependent on aerosol concentration, optical properties and altitude of the aerosol layer, we make use of complementary observations to fully diagnose the model, including AOD from the Multi-angle Imaging SpectroRadiometer (MISR), aerosol retrievals from the AErosol RObotic NETwork (AERONET) and attenuated backscatter coefficients from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) mission to ascertain potential misplacement of plume height by the model. By sampling dust, biomass burning and pollution events in 2007 we have compared model-produced AI and AAOD with the corresponding OMI products, identifying regions where the model representation of absorbing aerosols was deficient. As a result of this study over the Saharan dust region, we have obtained a new set of dust aerosol optical properties that retains consistency with the MODIS AOD data that were assimilated, while resulting in better agreement with aerosol absorption measurements from OMI. The analysis conducted over the southern African and South American biomass burning regions indicates that revising the spectrally dependent aerosol absorption properties in the near-UV region improves the modeled-observed AI comparisons

  16. Radiative Impact of Aerosols on the Regional Boundary Layer Features in Strong and Weak Wind Conditions using WRF Modeling System

    NASA Astrophysics Data System (ADS)

    Rajagopalan, R. A.; Sharan, M.

    2015-12-01

    Atmospheric aerosol particles play a vital role in the Earth's radiative energy budget. They exert a net cooling influence on climate by directly reflecting the solar radiation to space and by modifying the shortwave reflective properties of clouds. Radiation is the main source that regulates the surface energy budget. Surface temperature and planetary boundary layer (PBL) height depends on accurate calculation of both shortwave and longwave radiation. The weakening of the ambient winds is known to influence the structure of PBL. This study examines the sensitivity of the performance of Weather Research Forecasting (WRF) ARW Model to the use of different radiation schemes [For Long wave Radiation: Rapid Radiative Transfer Model (RRTM), Eta Geophysical Fluid Dynamics Laboratory (GFDL), Goddard, New Goddard, NCAR Community Atmosphere Model (CAM 3.0), New Goddard scheme, Fu-Liou-Gu scheme and for Short wave Radiation: Dudhia scheme, Eta Geophysical Fluid Dynamics Laboratory (GFDL), NCAR Community Atmosphere Model (CAM 3.0), New Goddard scheme]. Two different simulations are conducted one for the summer (14-15 May 2009) and winter (14-15 Dec 2008) season characterized by strong and weak wind conditions over India. Comparison of surface temperatures from different schemes for different cities (New Delhi, Ahmedabad, Lucknow, Kanpur, Jaipur and Jodhpur) on 14-15 May 2009 and 14-15 Dec 2008 with those observed shows the simulation with RRTM , New Goddard, and Fu-Liou-Gu schemes are closer to the observations as compared to other schemes. The temperature simulated from all the radiation schemes have more than 0.9 correlation coefficient but the root mean square error is relatively less in summer compared to winter season. It is surmised that Fu-Liou-Gu scheme performs better in almost all the cases. The reason behind can be the greater absorption of solar and IR radiative fluxes in the atmosphere and the surface provided in Fu-Liou-Gu radiation scheme than those computed in

  17. oVOC production from tropospheric alkyne oxidation and contribution to aerosol formation and growth

    NASA Astrophysics Data System (ADS)

    Goodall, Iain

    2013-04-01

    Ethyne (C2H2) is one of the simplest volatile organic compounds (VOC) and is predominantly emitted via anthropogenic processes and reacts with nitrogen oxides (NOx) in the presence of sunlight to form tropospheric ozone (O3). The dominant oxidation product of ethyne is the dicarbonyl species glyoxal (CHOCHO), which is thought to be a significant contributor to secondary organic aerosol (SOA) formation via irreversible oligomerisation reactions upon the surface of hydrated aerosol particulates and within cloud droplets. A series of chamber experiments were performed at the EUPHORE facility (Valencia, Spain) to study the atmospheric oxidation of ethyne, to determine oxidation product yields and to monitor SOA formation and growth by dicarbonyl oligomerisation. A Proton Transfer Reaction-Time of Flight- Mass Spectrometer (PTR-ToF-MS) was deployed by the University of Leicester to monitor precursor decay and the subsequent evolution of any gas-phase oxidised volatile organic compounds (oVOC). This was further complemented by a Broadband Cavity Enhanced Absorption Spectrometer (BBCEAS) for specific dicarbonyl and NO2 measurements. Aqueous extracts of chamber SOA were taken from filters collected during the experiments and subsequently analysed offline. The work explores the yields of low molecular weight products of ethyne oxidation for light and dark reactions, with varying levels of NOx and OH. Novel experiments were performed under atmospherically relevant conditions utilising natural lighting rather than artificial lighting. Reaction yields have been assessed with the aim of contributing to the ethyne and glyoxal mechanisms in the Master Chemical Mechanism (MCM; http://mcm.leeds.ac.uk/MCM), and have been compared with previously reported values determined from experiments performed under artificial lighting conditions.

  18. Airborne measurements of hygroscopicity and mixing state of aerosols in the planetary boundary layer during the PEGASOS campaigns

    NASA Astrophysics Data System (ADS)

    Rosati, Bernadette; Weingartner, Ernest; Gysel, Martin; Rubach, Florian; Mentel, Thomas; Baltensperger, Urs

    2014-05-01

    Aerosols interact directly with the incident solar radiation by scattering or absorbing the light. The optical properties of an aerosol particle can strongly be altered at enhanced relative humidity (RH). Depending on the particle's chemical composition, it can experience hygroscopic growth, leading to a change in size and index of refraction compared to the dry particle (Zieger et al., 2011). Besides, aerosols can exist in different mixing states which are usually divided into internal and external mixtures. If all particles of a certain size have the same chemical composition, they are described as internally mixed, whereas if particles of equal size have different chemical composition, they are defined as externally mixed. Depending on the mixture the hygroscopic behavior will change: internally mixed aerosols will grow uniformly with increasing RH, while the different substances in external mixtures will experience different growing behaviors leading to a mode-splitting or broadened size distribution. Laboratory studies are commonly performed at dry conditions but it is known that temperature and RH as well as chemical composition are changing with altitude (Morgan et al., 2010). This further leads to the conclusion that the in-situ measurements of optical properties at different heights are crucial for climate forcing calculations. Within the Pan-European Gas-Aerosols-climate interaction Study (PEGASOS) the white- light humidified optical particle spectrometer (WHOPS) was developed and installed on the Zeppelin to investigate changes of light scattering with regard to water uptake and altitude. This instrument firstly selects a dry monodisperse aerosol by its electrical mobility and then exposes it to a well-defined RH (typically 95%). Alternately, the dry and humidified particles are measured in a white-light optical particle spectrometer (WELAS). In this way it is possible to infer the effective index of refraction of the dry particles, their hygroscopic

  19. Observational constraints on glyoxal production from isoprene oxidation and its contribution to organic aerosol over the Southeast United States

    NASA Astrophysics Data System (ADS)

    Li, Jingyi; Mao, Jingqiu; Min, Kyung-Eun; Washenfelder, Rebecca A.; Brown, Steven S.; Kaiser, Jennifer; Keutsch, Frank N.; Volkamer, Rainer; Wolfe, Glenn M.; Hanisco, Thomas F.; Pollack, Ilana B.; Ryerson, Thomas B.; Graus, Martin; Gilman, Jessica B.; Lerner, Brian M.; Warneke, Carsten; Gouw, Joost A.; Middlebrook, Ann M.; Liao, Jin; Welti, André; Henderson, Barron H.; McNeill, V. Faye; Hall, Samuel R.; Ullmann, Kirk; Donner, Leo J.; Paulot, Fabien; Horowitz, Larry W.

    2016-08-01

    We use a 0-D photochemical box model and a 3-D global chemistry-climate model, combined with observations from the NOAA Southeast Nexus (SENEX) aircraft campaign, to understand the sources and sinks of glyoxal over the Southeast United States. Box model simulations suggest a large difference in glyoxal production among three isoprene oxidation mechanisms (AM3ST, AM3B, and Master Chemical Mechanism (MCM) v3.3.1). These mechanisms are then implemented into a 3-D global chemistry-climate model. Comparison with field observations shows that the average vertical profile of glyoxal is best reproduced by AM3ST with an effective reactive uptake coefficient γglyx of 2 × 10-3 and AM3B without heterogeneous loss of glyoxal. The two mechanisms lead to 0-0.8 µg m-3 secondary organic aerosol (SOA) from glyoxal in the boundary layer of the Southeast U.S. in summer. We consider this to be the lower limit for the contribution of glyoxal to SOA, as other sources of glyoxal other than isoprene are not included in our model. In addition, we find that AM3B shows better agreement on both formaldehyde and the correlation between glyoxal and formaldehyde (RGF = [GLYX]/[HCHO]), resulting from the suppression of δ-isoprene peroxy radicals. We also find that MCM v3.3.1 may underestimate glyoxal production from isoprene oxidation, in part due to an underestimated yield from the reaction of isoprene epoxydiol (IEPOX) peroxy radicals with HO2. Our work highlights that the gas-phase production of glyoxal represents a large uncertainty in quantifying its contribution to SOA.

  20. Dominance of organic aerosols in the marine boundary layer over the Gulf of Maine during NEAQS 2002 and their role in aerosol light scattering

    NASA Astrophysics Data System (ADS)

    Bates, T. S.; Quinn, P. K.; Coffman, D. J.; Johnson, J. E.; Middlebrook, A. M.

    2005-09-01

    Aerosol chemical, physical, and optical measurements were made aboard the NOAA R/V Ronald H. Brown off the coast of New England from July 12 through August 10, 2002, as part of the New England Air Quality Study (NEAQS). Measurements (generally 20 to 100 km from the coast) were made downwind of urban centers (New York City, Boston) and rural areas, and in air masses that had not been in contact with land for several days. On average during NEAQS, 75 ± 8% of the sub-10 μm aerodynamic diameter dry aerosol mass sampled 18 m above the sea surface was in the sub-1 μm fraction (size cut at 55% RH). The major submicrometer aerosol components were ammonium sulfate and particulate organic matter (POM, defined here as 1.6 times the mass concentration of organic carbon) comprising more than 92 ± 4% of the total mass. Under northwesterly flow with an average submicrometer total mass concentrations of 11 ± 4.5 μg m-3, POM was the dominant component (68 ± 8%) followed by (NH4)xHySO4 (23 ± 8%), inorganic oxidized material (IOM) (6 ± 4%), and EC (3 ± 1%). Under southwesterly flow with an average submicrometer total mass concentrations of 30 ± 11 μg m-3, (NH4)xHySO4 was the dominant component (54 ± 9%) followed by POM (41 ± 9%), IOM (3 ± 2%), and EC (2 ± 1%). Mie calculations using submicrometer nonrefractory (NR) POM and NR (NH4)xHySO4 + H2O size distributions to calculate submicrometer light scattering (σsp) at a wavelength of 550 nm suggest that POM was a dominant chemical component contributing to aerosol light scattering (haze) during NEAQS 2002, and contributed 60 ± 6 % and 57 ± 11 % to σsp at 55% RH during two pollution episodes off the New England Coast. These results are similar to those from the mid-Atlantic states during TARFOX but contrary to the long-term monitoring measurements over the continental northeast United States that show the New England haze is primarily a result of sulfate aerosol.

  1. Seasonal monitoring and estimation of regional aerosol distribution over Po valley, northern Italy, using a high-resolution MAIAC product

    NASA Astrophysics Data System (ADS)

    Arvani, Barbara; Pierce, R. Bradley; Lyapustin, Alexei I.; Wang, Yujie; Ghermandi, Grazia; Teggi, Sergio

    2016-09-01

    In this work, the new 1 km-resolved Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm is employed to characterize seasonal PM10 - AOD correlations over northern Italy. The accuracy of the new dataset is assessed compared to the widely used Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 5.1 Aerosol Optical Depth (AOD) data, retrieved at 0.55 μm with spatial resolution of 10 km (MYD04_L2). We focused on evaluating the ability of these two products to characterize both temporal and spatial distributions of aerosols within urban and suburban areas. Ground PM10 measurements were obtained from 73 of the Italian Regional Agency for Environmental Protection (ARPA) monitoring stations, spread across northern Italy, during a three-year period from 2010 to 2012. The Po Valley area (northern Italy) was chosen as the study domain because of its severe urban air pollution, resulting from it having the highest population and industrial manufacturing density in the country, being located in a valley where two surrounding mountain chains favor the stagnation of pollutants. We found that the global correlations between the bin-averaged PM10 and AOD are R2 = 0.83 and R2 = 0.44 for MYD04_L2 and for MAIAC, respectively, suggesting a greater sensitivity of the high-resolution product to small-scale deviations. However, the introduction of Relative Humidity (RH) and Planetary Boundary Layer (PBL) depth corrections allowed for a significant improvement to the bin-averaged PM - AOD correlation, which led to a similar performance: R2 = 0.96 for MODIS and R2 = 0.95 for MAIAC. Furthermore, the introduction of the PBL information in the corrected AOD values was found to be crucial in order to capture the clear seasonal cycle shown by measured PM10 values. The study allowed us to define four seasonal linear correlations that estimate PM10 concentrations satisfactorily from the remotely sensed MAIAC AOD retrieval. Overall, the results show that

  2. Seasonal monitoring and estimation of regional aerosol distribution over Po valley, northern Italy, using a high-resolution MAIAC product

    NASA Astrophysics Data System (ADS)

    Arvani, Barbara; Pierce, R. Bradley; Lyapustin, Alexei I.; Wang, Yujie; Ghermandi, Grazia; Teggi, Sergio

    2016-09-01

    In this work, the new 1 km-resolved Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm is employed to characterize seasonal PM10 - AOD correlations over northern Italy. The accuracy of the new dataset is assessed compared to the widely used Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 5.1 Aerosol Optical Depth (AOD) data, retrieved at 0.55 μm with spatial resolution of 10 km (MYD04_L2). We focused on evaluating the ability of these two products to characterize both temporal and spatial distributions of aerosols within urban and suburban areas. Ground PM10 measurements were obtained from 73 of the Italian Regional Agency for Environmental Protection (ARPA) monitoring stations, spread across northern Italy, during a three-year period from 2010 to 2012. The Po Valley area (northern Italy) was chosen as the study domain because of its severe urban air pollution, resulting from it having the highest population and industrial manufacturing density in the country, being located in a valley where two surrounding mountain chains favor the stagnation of pollutants. We found that the global correlations between the bin-averaged PM10 and AOD are R2 = 0.83 and R2 = 0.44 for MYD04_L2 and for MAIAC, respectively, suggesting a greater sensitivity of the high-resolution product to small-scale deviations. However, the introduction of Relative Humidity (RH) and Planetary Boundary Layer (PBL) depth corrections allowed for a significant improvement to the bin-averaged PM - AOD correlation, which led to a similar performance: R2 = 0.96 for MODIS and R2 = 0.95 for MAIAC. Furthermore, the introduction of the PBL information in the corrected AOD values was found to be crucial in order to capture the clear seasonal cycle shown by measured PM10 values. The study allowed us to define four seasonal linear correlations that estimate PM10 concentrations satisfactorily from the remotely sensed MAIAC AOD retrieval. Overall, the results show that the high

  3. Quality, compatibility, and synergy analyses of global aerosol products derived from the advanced very high resolution radiometer and Total Ozone Mapping Spectrometer

    NASA Astrophysics Data System (ADS)

    Jeong, Myeong-Jae; Li, Zhanqing

    2005-05-01

    A number of global aerosol products of varying quality, strengths, and weaknesses have been generated. Presented here are synthetic analyses with regard to the quality, compatibility, and synergy of two long-term global (1983-2000) aerosol products derived from the advanced very high resolution radiometer (AVHRR) and the Total Ozone Mapping Spectrometer (TOMS). Four essential aerosol parameters, namely, aerosol optical thickness (AOT) from AVHRR under the Global Aerosol Climatology Project (GACP), TOMS AOT, Ångström exponent (AE) from AVHRR, and TOMS aerosol index (AI) are analyzed together with various ancillary data sets on meteorological fields, ocean color, and ground-based AOT measurements. While the two satellite products reveal some common features, significant discrepancies exist. Reflectances measured at ultraviolet and visible wavelengths from the two sensors are incompatible in terms of the magnitude of AE computed from AOT derived from the two channels. The spatial distributions of the aerosol products from AVHRR and TOMS are complimentary in revealing different aspects of aerosol characteristics. In-depth analyses were carried out over several regions under the influence of different types of aerosols such as biomass burning, dust, sea salt, air pollution, and their mixtures. A classification algorithm was developed to identify dominant types of aerosols around the globe using aerosol products from the two instruments. Aerosol type information is used to develop and apply relationships between the AVHRR AOT and the TOMS AOT. The latter was used to extend the AOT at 0.55 μm over land around the globe. Comparisons of monthly mean AOTs with AERONET monthly mean AOTs showed a general agreement to within an estimated error range of ±0.08 ± 0.20τ. Finally, a comparison between the estimated AOT with Moderate Resolution Imaging Spectroradiometer (MODIS) AOT over land showed good agreement in terms of magnitude and seasonality, suggesting a means of

  4. Temporal and spectral cloud screening of polar winter aerosol optical depth (AOD): impact of homogeneous and inhomogeneous clouds and crystal layers on climatological-scale AODs

    NASA Astrophysics Data System (ADS)

    O'Neill, Norman T.; Baibakov, Konstantin; Hesaraki, Sareh; Ivanescu, Liviu; Martin, Randall V.; Perro, Chris; Chaubey, Jai P.; Herber, Andreas; Duck, Thomas J.

    2016-10-01

    We compared star-photometry-derived, polar winter aerosol optical depths (AODs), acquired at Eureka, Nunavut, Canada, and Ny-Ålesund, Svalbard, with GEOS-Chem (GC) simulations as well as ground-based lidar and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) retrievals over a sampling period of two polar winters. The results indicate significant cloud and/or low-altitude ice crystal (LIC) contamination which is only partially corrected using temporal cloud screening. Spatially homogeneous clouds and LICs that remain after temporal cloud screening represent an inevitable systematic error in the estimation of AOD: this error was estimated to vary from 78 to 210 % at Eureka and from 2 to 157 % at Ny-Ålesund. Lidar analysis indicated that LICs appeared to have a disproportionately large influence on the homogeneous coarse-mode optical depths that escape temporal cloud screening. In principle, spectral cloud screening (to yield fine-mode or submicron AODs) reduces pre-cloud-screened AODs to the aerosol contribution if one assumes that coarse-mode (super-micron) aerosols are a minor part of the AOD. Large, low-frequency differences between these retrieved values and their GC analogue appeared to be often linked to strong, spatially extensive planetary boundary layer events whose presence at either site was inferred from CALIOP profiles. These events were either not captured or significantly underestimated by the GC simulations. High-frequency AOD variations of GC fine-mode aerosols at Ny-Ålesund were attributed to sea salt, while low-frequency GC variations at Eureka and Ny-Ålesund were attributable to sulfates. CALIOP profiles and AODs were invaluable as spatial and temporal redundancy support (or, alternatively, as insightful points of contention) for star photometry retrievals and GC estimates of AOD.

  5. Kinetics of oxygenated product formation during the heterogeneous oxidation of organic aerosol

    NASA Astrophysics Data System (ADS)

    Kolesar, K. R.; Cappa, C. D.; Wilson, K. R.

    2014-12-01

    Oxidation of organic aerosols can lead to changes in their atmospheric lifetime, optical properties and health effects. Whereas much is known about the rates of reaction and subsequent branching ratios of gas-phase organic species, much less is known about their condensed phase counterparts. The determination of the kinetics and abundances of the oxidation products associated with condensed phase reactions is needed to understand the oxidation reaction pathways and their branching ratios. The Vacuum Ultraviolet Aerosol Mass Spectrometer (VUV-AMS) at the Chemical Dynamics Beamline at Lawrence Berkeley National Laboratory has been useful in determining the reaction rate constants for a number of condensed phase organic compounds with oxidants such as OH and O3. The relatively soft ionization in the VUV-AMS leads to substantially less fragmentation than other AMS instruments that use electron impact ionization, and therefore preserves a greater amount of molecular information about parent molecules. Previously, ketones formed from the heterogenous oxidation of model organic compounds have been identified and their formation kinetics quantified. However, other possible products, such as alcohols and organic peroxides, have not previously been identified in the VUV-AMS mass spectra or characterized as these are subject to greater fragmentation. Here, we present a method in which the fragmentation pattern is specified for each alcohol isomer formed from the oxidation of two model organic compounds, bis-2-ethylhexl sebacate and squalane. From this we are able to define unique m/z fragments for each isomer from which we derive information about alcohol and abundances. This study demonstrates additional methods for the analysis of mass spectra obtained with the VUV-AMS as well as provides insights into condensed phase oxidation kinetics.

  6. Aerosol Climate Time Series Evaluation In ESA Aerosol_cci

    NASA Astrophysics Data System (ADS)

    Popp, T.; de Leeuw, G.; Pinnock, S.

    2015-12-01

    Within the ESA Climate Change Initiative (CCI) Aerosol_cci (2010 - 2017) conducts intensive work to improve algorithms for the retrieval of aerosol information from European sensors. By the end of 2015 full mission time series of 2 GCOS-required aerosol parameters are completely validated and released: Aerosol Optical Depth (AOD) from dual view ATSR-2 / AATSR radiometers (3 algorithms, 1995 - 2012), and stratospheric extinction profiles from star occultation GOMOS spectrometer (2002 - 2012). Additionally, a 35-year multi-sensor time series of the qualitative Absorbing Aerosol Index (AAI) together with sensitivity information and an AAI model simulator is available. Complementary aerosol properties requested by GCOS are in a "round robin" phase, where various algorithms are inter-compared: fine mode AOD, mineral dust AOD (from the thermal IASI spectrometer), absorption information and aerosol layer height. As a quasi-reference for validation in few selected regions with sparse ground-based observations the multi-pixel GRASP algorithm for the POLDER instrument is used. Validation of first dataset versions (vs. AERONET, MAN) and inter-comparison to other satellite datasets (MODIS, MISR, SeaWIFS) proved the high quality of the available datasets comparable to other satellite retrievals and revealed needs for algorithm improvement (for example for higher AOD values) which were taken into account for a reprocessing. The datasets contain pixel level uncertainty estimates which are also validated. The paper will summarize and discuss the results of major reprocessing and validation conducted in 2015. The focus will be on the ATSR, GOMOS and IASI datasets. Pixel level uncertainties validation will be summarized and discussed including unknown components and their potential usefulness and limitations. Opportunities for time series extension with successor instruments of the Sentinel family will be described and the complementarity of the different satellite aerosol products

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

    PubMed

    Pal, S; Lee, T R; Phelps, S; De Wekker, S F J

    2014-10-15

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

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

    PubMed

    Pal, S; Lee, T R; Phelps, S; De Wekker, S F J

    2014-10-15

    The development of the atmospheric boundary layer (ABL) plays a key role in affecting the variability of atmospheric constituents such as aerosols, greenhouse gases, water vapor, and ozone. In general, the concentration of any tracers within the ABL varies due to the changes in the mixing volume (i.e. ABL depth). In this study, we investigate the impact on the near-surface aerosol concentration in a valley site of 1) the boundary layer dilution due to vertical mixing and 2) changes in the wind patterns. We use a data set obtained during a 10-day field campaign in which a number of remote sensing and in-situ instruments were deployed, including a ground-based aerosol lidar system for monitoring of the ABL top height (zi), a particle counter to determine the number concentration of aerosol particles at eight different size ranges, and tower-based standard meteorological instruments. Results show a clearly visible decreasing trend of the mean daytime zi from 2900 m AGL (above ground level) to 2200 m AGL during a three-day period which resulted in increased near-surface pollutant concentrations. An inverse relationship exists between the zi and the fine fraction (0.3-0.7 μm) accumulation mode particles (AMP) on some days due to the dilution effect in a well-mixed ABL. These days are characterized by the absence of daytime upvalley winds and the presence of northwesterly synoptic-driven winds. In contrast, on the days with an onset of an upvalley wind circulation after the morning transition, the wind-driven local transport mechanism outweighs the ABL-dilution effect in determining the variability of AMP concentration. The interplay between the ABL depth evolution and the onset of the upvalley wind during the morning transition period significantly governs the air quality in a valley and could be an important component in the studies of mountain meteorology and air quality. PMID:25105753

  9. Aerosol Remote Sensing from OMI Observations: An Overview

    NASA Technical Reports Server (NTRS)

    Torres, Omar; Ahn, Changwoo; Jethva, Hiren T.

    2014-01-01

    The unique advantage of OMI observations for the characterization of aerosol properties is the availability of radiance measurement at near UV wavelengths. In spite of its coarse spatial resolution, OMI's near UV observations make possible the characterization of aerosol absorption properties. This capability is unavailable in any of the currently operational high spatial resolution aerosol sensors. A unique decadal record of aerosol absorption optical depth and single scattering albedo from near UV observations has been produced from OMI observations. In this presentation we will review the evolution of OMI's aerosol retrieval capability over the past ten years including retrieval algorithm improvements, assessment of retrieved products, and development of new retrieval capabilities to infer the optical depth of aerosol layers located above clouds.

  10. Secondary organic aerosol production from diesel vehicle exhaust: impact of aftertreatment, fuel chemistry and driving cycle

    NASA Astrophysics Data System (ADS)

    Gordon, T. D.; Presto, A. A.; Nguyen, N. T.; Robertson, W. H.; Na, K.; Sahay, K. N.; Zhang, M.; Maddox, C.; Rieger, P.; Chattopadhyay, S.; Maldonado, H.; Maricq, M. M.; Robinson, A. L.

    2014-05-01

    Environmental chamber ("smog chamber") experiments were conducted to investigate secondary organic aerosol (SOA) production from dilute emissions from two medium-duty diesel vehicles (MDDVs) and three heavy-duty diesel vehicles (HDDVs) under urban-like conditions. Some of the vehicles were equipped with emission control aftertreatment devices, including diesel particulate filters (DPFs), selective catalytic reduction (SCR) and diesel oxidation catalysts (DOCs). Experiments were also performed with different fuels (100% biodiesel and low-, medium- or high-aromatic ultralow sulfur diesel) and driving cycles (Unified Cycle,~Urban Dynamometer Driving Schedule, and creep + idle). During normal operation, vehicles with a catalyzed DPF emitted very little primary particulate matter (PM). Furthermore, photooxidation of dilute emissions from these vehicles produced essentially no SOA (below detection limit). However, significant primary PM emissions and SOA production were measured during active DPF regeneration experiments. Nevertheless, under reasonable assumptions about DPF regeneration frequency, the contribution of regeneration emissions to the total vehicle emissions is negligible, reducing PM trapping efficiency by less than 2%. Therefore, catalyzed DPFs appear to be very effective in reducing both primary PM emissions and SOA production from diesel vehicles. For both MDDVs and HDDVs without aftertreatment substantial SOA formed in the smog chamber - with the emissions from some vehicles generating twice as much SOA as primary organic aerosol after 3 h of oxidation at typical urban VOC / NOx ratios (3 : 1). Comprehensive organic gas speciation was performed on these emissions, but less than half of the measured SOA could be explained by traditional (speciated) SOA precursors. The remainder presumably originates from the large fraction (~30%) of the nonmethane organic gas emissions that could not be speciated using traditional one-dimensional gas chromatography. The

  11. A 4-D climatology (1979-2009) of the monthly tropospheric aerosol optical depth distribution over the Mediterranean region from a comparative evaluation and blending of remote sensing and model products

    NASA Astrophysics Data System (ADS)

    Nabat, P.; Somot, S.; Mallet, M.; Chiapello, I.; Morcrette, J. J.; Solmon, F.; Szopa, S.; Dulac, F.; Collins, W.; Ghan, S.; Horowitz, L. W.; Lamarque, J. F.; Lee, Y. H.; Naik, V.; Nagashima, T.; Shindell, D.; Skeie, R.

    2013-05-01

    aerosols showing a large vertical spread, and other continental and marine aerosols which are confined in the boundary layer. From this compilation, we propose a 4-D blended product from model and satellite data, consisting in monthly time series of 3-D aerosol distribution at a 50 km horizontal resolution over the Euro-Mediterranean marine and continental region for the 2003-2009 period. The product is based on the total AOD from AQUA/MODIS, apportioned into sulfates, black and organic carbon from the MACC reanalysis, and into dust and sea-salt aerosols from RegCM-4 simulations, which are distributed vertically based on CALIOP climatology. We extend the 2003-2009 reconstruction to the past up to 1979 using the 2003-2009 average and applying the decreasing trend in sulfate aerosols from LMDz-OR-INCA, whose AOD trends over Europe and the Mediterranean are median among the ACCMIP models. Finally optical properties of the different aerosol types in this region are proposed from Mie calculations so that this reconstruction can be included in regional climate models for aerosol radiative forcing and aerosol-climate studies.

  12. A 4-D Climatology (1979-2009) of the Monthly Tropospheric Aerosol Optical Depth Distribution over the Mediterranean Region from a Comparative Evaluation and Blending of Remote Sensing and Model Products

    NASA Technical Reports Server (NTRS)

    Nabat, P.; Somot, S.; Mallet, M.; Chiapello, I; Morcrette, J. J.; Solomon, F.; Szopa, S.; Dulac, F; Collins, W.; Ghan, S.; Horowitz, L. W.; Lamarque, J. F.; Lee, Y. H.; Naik, V.; Nagashima, T.; Shindell, D.; Skeie, R.

    2013-01-01

    aerosols showing a large vertical spread, and other continental and marine aerosols which are confined in the boundary layer. From this compilation, we propose a 4-D blended product from model and satellite data, consisting in monthly time series of 3-D aerosol distribution at a 50 km horizontal resolution over the Euro-Mediterranean marine and continental region for the 2003-2009 period. The product is based on the total AOD from AQUA/MODIS, apportioned into sulfates, black and organic carbon from the MACC reanalysis, and into dust and sea-salt aerosols from RegCM-4 simulations, which are distributed vertically based on CALIOP climatology.We extend the 2003-2009 reconstruction to the past up to 1979 using the 2003-2009 average and applying the decreasing trend in sulfate aerosols from LMDz-OR-INCA, whose AOD trends over Europe and the Mediterranean are median among the ACCMIP models. Finally optical properties of the different aerosol types in this region are proposed from Mie calculations so that this reconstruction can be included in regional climate models for aerosol radiative forcing and aerosol-climate studies.

  13. The Statistical Evolution of Multiple Generations of Oxidation Products in the Photochemical Aging of Chemically Reduced Organic Aerosol

    SciTech Connect

    Wilson, Kevin R.; Smith, Jared D.; Kessler, Sean; Kroll, Jesse H.

    2011-10-03

    The heterogeneous reaction of hydroxyl radicals (OH) with squalane and bis(2-ethylhexyl) sebacate (BES) particles are used as model systems to examine how distributions of reactionproducts evolve during the oxidation of chemically reduced organic aerosol. A kinetic model of multigenerational chemistry, which is compared to previously measured (squalane) and new(BES) experimental data, reveals that it is the statistical mixtures of different generations of oxidation products that control the average particle mass and elemental composition during thereaction. The model suggests that more highly oxidized reaction products, although initially formed with low probability, play a large role in the production of gas phase reaction products.In general, these results highlight the importance of considering atmospheric oxidation as a statistical process, further suggesting that the underlying distribution of molecules could playimportant roles in aerosol formation as well as in the evolution of key physicochemical properties such as volatility and hygroscopicity.

  14. Radiative Effects of Aerosols

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.

    1997-01-01

    During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size resolved aerosol microphysics and chemistry. Both profiles included pollution haze layer from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core.

  15. Secondary organic aerosol from ozone-initiated reactions with terpene-rich household products

    SciTech Connect

    Coleman, Beverly; Coleman, Beverly K.; Lunden, Melissa M.; Destaillats, Hugo; Nazaroff, William W.

    2008-01-01

    We analyzed secondary organic aerosol (SOA) data from a series of small-chamber experiments in which terpene-rich vapors from household products were combined with ozone under conditions analogous to product use indoors. Reagents were introduced into a continuously ventilated 198 L chamber at steady rates. Consistently, at the time of ozone introduction, nucleation occurred exhibiting behavior similar to atmospheric events. The initial nucleation burst and growth was followed by a period in which approximately stable particle levels were established reflecting a balance between new particle formation, condensational growth, and removal by ventilation. Airborne particles were measured with a scanning mobility particle sizer (SMPS, 10 to 400 nm) in every experiment and with an optical particle counter (OPC, 0.1 to 2.0 ?m) in a subset. Parameters for a three-mode lognormal fit to the size distribution at steady state were determined for each experiment. Increasing the supply ozone level increased the steady-state mass concentration and yield of SOA from each product tested. Decreasing the air-exchange rate increased the yield. The steady-state fine-particle mass concentration (PM1.1) ranged from 10 to> 300 mu g m-3 and yields ranged from 5percent to 37percent. Steady-state nucleation rates and SOA mass formation rates were on the order of 10 cm-3 s-1 and 10 mu g m-3 min-1, respectively.

  16. Secondary organic aerosol production from diesel vehicle exhaust: impact of aftertreatment, fuel chemistry and driving cycle

    NASA Astrophysics Data System (ADS)

    Gordon, T. D.; Presto, A. A.; Nguyen, N. T.; Robertson, W. H.; Na, K.; Sahay, K. N.; Zhang, M.; Maddox, C.; Rieger, P.; Chattopadhyay, S.; Maldonado, H.; Maricq, M. M.; Robinson, A. L.

    2013-09-01

    Environmental chamber ("smog chamber") experiments were conducted to investigate secondary organic aerosol (SOA) production from dilute emissions from two medium-duty diesel vehicles (MDDVs) and three heavy-duty diesel vehicles (HDDVs) under urban-like conditions. Some of the vehicles were equipped with emission control aftertreatment devices including diesel particulate filters (DPF), selective catalytic reduction (SCR) and diesel oxidation catalysts (DOC). Experiments were also performed with different fuels (100% biodiesel and low-, medium- or high-aromatic ultralow sulfur diesel) and driving cycles (Unified Cycle, Urban Dynamometer Driving Schedule, and creep+idle). During normal operation, vehicles with a catalyzed DPF emitted very little primary particulate matter (PM). Furthermore, photo-oxidation of dilute emissions from these vehicles produced essentially no SOA (below detection limit). However, significant primary PM emissions and SOA production were measured during active DPF regeneration experiments. Nevertheless, under reasonable assumptions about DPF regeneration frequency, the contribution of regeneration emissions to the total vehicle emissions is negligible, reducing PM trapping efficiency by less than 2%. Therefore, catalyzed DPFs appear to be very effective in reducing both primary and secondary fine particulate matter from diesel vehicles. For both MDDVs and HDDVs without aftertreatment substantial SOA formed in the smog chamber - with the emissions from some vehicles generating twice as much SOA as primary organic aerosol after three hours of oxidation at typical urban VOC : NOx ratios (3:1). Comprehensive organic gas speciation was performed on these emissions, but less than half of the measured SOA could be explained by traditional (speciated) SOA precursors. The remainder presumably originates from the large fraction (~30%) of the non-methane organic gas emissions that could not be speciated using traditional one-dimensional gas

  17. The use of MODIS data and aerosol products for air quality prediction

    NASA Astrophysics Data System (ADS)

    Hutchison, Keith D.; Smith, Solar; Faruqui, Shazia

    2004-09-01

    The Center for Space Research (CSR) is exploring new approaches to integrate data collected by the MODerate resolution Imaging Spectroradiometer (MODIS) sensor, flown on NASA's Earth Observing System (EOS) satellites, into a real-time prediction methodology to support operational air quality forecasts issued by the Monitoring Operations Division (MOD) of the Texas Commission on Environmental Quality (TCEQ). Air pollution is a widespread problem in the United States, with over 130 million individuals exposed to levels of air pollution that exceed one or more health-based standards. Texas air quality is under assault by a variety of anthropogenic sources associated with a rapidly growing population along with increases in emissions from the diesel engines that drive international trade between the US and Central America. The challenges of meeting air quality standards established by the Environmental Protection Agency are further impacted by the transport of pollution into Texas that originates from outside its borders and are cumulative with those generated by local sources. In an earlier study, CSR demonstrated the value of MODIS imagery and aerosol products for monitoring ozone-laden pollution that originated in the central US before migrating into Texas and causing TCEQ to issue a health alert for 150 counties. Now, data from this same event are re-analyzed in an attempt to predict air quality from MODIS aerosol optical thickness (AOT) observations. The results demonstrate a method to forecast air quality from remotely sensed satellite observations when the transient pollution can be isolated from local sources. These pollution sources can be separated using TCEQ's network of ground-based Continuous Air quality Monitoring (CAM) stations.

  18. Retrieval of effective complex refractive index from intensive measurements of characteristics of ambient aerosols in the boundary layer.

    PubMed

    Zhang, Xiaolin; Huang, Yinbo; Rao, Ruizhong; Wang, Zhien

    2013-07-29

    Aerosol complex refractive index (ACRI) has attracted intensive attentions due to its significance in modeling aerosol radiative effects. Determinations of ACRI from surface measurements of aerosol scattering and absorption coefficients as well as number size distributions during June, 2008 based on an iterative Mie algorithm were performed. The aim of our study was to introduce an inversion approach with the merits of high time-resolutions to retrieve the optically effective ACRI, especially its imaginary part. Based on simultaneous measurements of aerosol characteristics, mean ACRI value of 1.50 ( ± 0.34)-i0.025 ( ± 0.015) at 550 nm in Hefei in summer was deducted. The lower imaginary parts with higher single scattering albedos and lower scattering Angstrom exponents were obtained for haze periods compared with nonhaze conditions with similar air-mass back-trajectories, indicating more large and scattering particles contributing to the formation of haze episodes. The derived imaginary parts of ACRI related to agricultural biomass burning were in the range from 0.013 to 0.029 at 550 nm. Significant negative correlations between retrieved imaginary parts of ACRI and measured single scattering albedos indicate that our retrieval approach is a reasonable method for determining the imaginary parts of complex refractive indices of aerosol particles.

  19. Continuous production of nanostructured particles using spatial atomic layer deposition

    SciTech Connect

    Ommen, J. Ruud van Kooijman, Dirkjan; Niet, Mark de; Talebi, Mojgan; Goulas, Aristeidis

    2015-03-15

    In this paper, the authors demonstrate a novel spatial atomic layer deposition (ALD) process based on pneumatic transport of nanoparticle agglomerates. Nanoclusters of platinum (Pt) of ∼1 nm diameter are deposited onto titania (TiO{sub 2}) P25 nanoparticles resulting to a continuous production of an active photocatalyst (0.12–0.31 wt. % of Pt) at a rate of about 1 g min{sup −1}. Tuning the precursor injection velocity (10–40 m s{sup −1}) enhances the contact between the precursor and the pneumatically transported support flows. Decreasing the chemisorption temperature (from 250 to 100 °C) results in more uniform distribution of the Pt nanoclusters as it decreases the reaction rate as compared to the rate of diffusion into the nanoparticle agglomerates. Utilizing this photocatalyst in the oxidation reaction of Acid Blue 9 showed a factor of five increase of the photocatalytic activity compared to the native P25 nanoparticles. The use of spatial particle ALD can be further expanded to deposition of nanoclusters on porous, micron-sized particles and to the production of core–shell nanoparticles enabling the robust and scalable manufacturing of nanostructured powders for catalysis and other applications.

  20. Effect of temperature, atmospheric condition, and particle size on extinction in a plume of volatile aerosol dispersed in the atmospheric surface layer.

    PubMed

    Tsang, T T; Pai, P; Korgaonkar, N V

    1988-02-01

    The objective of this work is to study the effects of ambient temperature, atmospheric condition, and particle size on the extinction coefficient of diesel fuel and fog oil smoke. A first-order closure model is used to describe the turbulent diffusion of the smoke in the atmospheric surface layer. Mean values of wind speed and diffusivity in the vertical direction are obtained by the use of the Monin-Obukhov similarity theory. The 2-D crosswind line source model also includes the aerosol kinetic processes of evaporation, sedimentation, and deposition. Numerical results are obtained from simulations on a supercomputer.

  1. Production of Inhalable Submicrometer Aerosols from Conventional Mesh Nebulizers for Improved Respiratory Drug Delivery

    PubMed Central

    Longest, P. Worth; Spence, Benjamin M.; Holbrook, Landon T.; Mossi, Karla M.; Son, Yoen-Ju; Hindle, Michael

    2012-01-01

    Submicrometer and nanoparticle aerosols may significantly improve the delivery efficiency, dissolution characteristics, and bioavailability of inhaled pharmaceuticals. The objective of this study was to explore the formation of submicrometer and nanometer aerosols from mesh nebulizers suitable for respiratory drug delivery using experiments and computational fluid dynamics (CFD) modeling. Mesh nebulizers were coupled with add-on devices to promote aerosol drying and the formation of submicrometer particles, as well as to control the inhaled aerosol temperature and relative humidity. Cascade impaction experiments were used to determine the initial mass median aerodynamic diameters of 0.1% albuterol aerosols produced by the AeroNeb commercial (4.69 μm) and lab (3.90 μm) nebulizers and to validate the CFD model in terms of droplet evaporation. Through an appropriate selection of flow rates, nebulizers, and model drug concentrations, submicrometer and nanometer aerosols could be formed with the three devices considered. Based on CFD simulations, a wire heated design was shown to overheat the airstream producing unsafe conditions for inhalation if the aerosol was not uniformly distributed in the tube cross-section or if the nebulizer stopped producing droplets. In comparison, a counter-flow heated design provided sufficient thermal energy to produce submicrometer particles, but also automatically limited the maximum aerosol outlet temperature based on the physics of heat transfer. With the counter-flow design, submicrometer aerosols were produced at flow rates of 5, 15, and 30 LPM, which may be suitable for various forms of oral and nasal aerosol delivery. Thermodynamic conditions of the aerosol stream exiting the counter-flow design were found be in a range of 21-45 °C with relative humidity greater than 40% in some cases, which was considered safe for direct inhalation and advantageous for condensational growth delivery. PMID:22707794

  2. Effect of heavy haze and aerosol pollution on rice and wheat productions in China.

    PubMed

    Tie, Xuexi; Huang, Ru-Jin; Dai, Wenting; Cao, Junji; Long, Xin; Su, Xiaoli; Zhao, Shuyu; Wang, Qiyuan; Li, Guohui

    2016-01-01

    In China, regional haze pollution is a serious environmental problem. The impact on ecosystem, however, is not clearly understood. This study investigates the effect of regional haze pollution on the yields of rice and wheat in China. The spatial and temporal distributions of aerosol optical depth (AOD) show high particulate pollution in the North China Plain region, Yangtze River Delta region, the central eastern China, and the Si Chuan Basin, coexisted largely with crop growth in time and space. The solar irradiance reaching these regions is estimated to reduce by up to 28-49%, calculated using the AOD distributions and tropospheric ultraviolet-visible (TUV) model. Reduction of solar irradiance in these regions can depress optimal yields of about 45% of rice and 75% of wheat growth in China, leading to 2% reduction in total rice production and 8% reduction in total wheat production in China. However, there are large uncertainties of the estimate related to the diffuse solar radiation. For high diffuse radiation case, the estimate reductions of rice and wheat decrease to 1% and 4.5%, respectively. A further detailed study is needed to clearly understand this effect to meet the growing food demand in the nation in the coming decades. PMID:27388031

  3. Effect of heavy haze and aerosol pollution on rice and wheat productions in China

    PubMed Central

    Tie, Xuexi; Huang, Ru-Jin; Dai, Wenting; Cao, Junji; Long, Xin; Su, Xiaoli; Zhao, Shuyu; Wang, Qiyuan; Li, Guohui

    2016-01-01

    In China, regional haze pollution is a serious environmental problem. The impact on ecosystem, however, is not clearly understood. This study investigates the effect of regional haze pollution on the yields of rice and wheat in China. The spatial and temporal distributions of aerosol optical depth (AOD) show high particulate pollution in the North China Plain region, Yangtze River Delta region, the central eastern China, and the Si Chuan Basin, coexisted largely with crop growth in time and space. The solar irradiance reaching these regions is estimated to reduce by up to 28–49%, calculated using the AOD distributions and tropospheric ultraviolet-visible (TUV) model. Reduction of solar irradiance in these regions can depress optimal yields of about 45% of rice and 75% of wheat growth in China, leading to 2% reduction in total rice production and 8% reduction in total wheat production in China. However, there are large uncertainties of the estimate related to the diffuse solar radiation. For high diffuse radiation case, the estimate reductions of rice and wheat decrease to 1% and 4.5%, respectively. A further detailed study is needed to clearly understand this effect to meet the growing food demand in the nation in the coming decades. PMID:27388031

  4. Effect of heavy haze and aerosol pollution on rice and wheat productions in China.

    PubMed

    Tie, Xuexi; Huang, Ru-Jin; Dai, Wenting; Cao, Junji; Long, Xin; Su, Xiaoli; Zhao, Shuyu; Wang, Qiyuan; Li, Guohui

    2016-07-08

    In China, regional haze pollution is a serious environmental problem. The impact on ecosystem, however, is not clearly understood. This study investigates the effect of regional haze pollution on the yields of rice and wheat in China. The spatial and temporal distributions of aerosol optical depth (AOD) show high particulate pollution in the North China Plain region, Yangtze River Delta region, the central eastern China, and the Si Chuan Basin, coexisted largely with crop growth in time and space. The solar irradiance reaching these regions is estimated to reduce by up to 28-49%, calculated using the AOD distributions and tropospheric ultraviolet-visible (TUV) model. Reduction of solar irradiance in these regions can depress optimal yields of about 45% of rice and 75% of wheat growth in China, leading to 2% reduction in total rice production and 8% reduction in total wheat production in China. However, there are large uncertainties of the estimate related to the diffuse solar radiation. For high diffuse radiation case, the estimate reductions of rice and wheat decrease to 1% and 4.5%, respectively. A further detailed study is needed to clearly understand this effect to meet the growing food demand in the nation in the coming decades.

  5. Effect of heavy haze and aerosol pollution on rice and wheat productions in China

    NASA Astrophysics Data System (ADS)

    Tie, Xuexi; Huang, Ru-Jin; Dai, Wenting; Cao, Junji; Long, Xin; Su, Xiaoli; Zhao, Shuyu; Wang, Qiyuan; Li, Guohui

    2016-07-01

    In China, regional haze pollution is a serious environmental problem. The impact on ecosystem, however, is not clearly understood. This study investigates the effect of regional haze pollution on the yields of rice and wheat in China. The spatial and temporal distributions of aerosol optical depth (AOD) show high particulate pollution in the North China Plain region, Yangtze River Delta region, the central eastern China, and the Si Chuan Basin, coexisted largely with crop growth in time and space. The solar irradiance reaching these regions is estimated to reduce by up to 28–49%, calculated using the AOD distributions and tropospheric ultraviolet-visible (TUV) model. Reduction of solar irradiance in these regions can depress optimal yields of about 45% of rice and 75% of wheat growth in China, leading to 2% reduction in total rice production and 8% reduction in total wheat production in China. However, there are large uncertainties of the estimate related to the diffuse solar radiation. For high diffuse radiation case, the estimate reductions of rice and wheat decrease to 1% and 4.5%, respectively. A further detailed study is needed to clearly understand this effect to meet the growing food demand in the nation in the coming decades.

  6. A 4-D Climatology (1979-2009) of the Monthly Tropospheric Aerosol Optical Depth Distribution over the Mediterranean Region from a Comparative Evaluation and Blending of Remote Sensing and Model Products

    SciTech Connect

    Nabat, P.; Somot, S.; Mallet, M.; Chiapello, I.; Morcrette, J. -J.; Solmon, F.; Szopa, S.; Dulac, F.; Collins, W.; Ghan, Steven J.; Horowitz, L.; Lamarque, J.-F.; Lee, Y. H.; Naik, Vaishali; Nagashima, T.; Shindell, Drew; Skeie, R. B.

    2013-05-17

    showing a large vertical spread, and other continental and marine aerosols which are confined in the boundary layer. From this compilation, we propose a 4-D blended product from model and satellite data, consisting in monthly time series of 3-D aerosol distribution at a 50 km horizontal resolution over the Euro-Mediterranean marine and continental region for the 2003–2009 period. The product is based on the total AOD from AQUA/MODIS, apportioned into sulfates, black and organic carbon from the MACC reanalysis, and into dust and sea-salt aerosols from RegCM-4 simulations, which are distributed vertically based on CALIOP climatology.We extend the 2003–2009 reconstruction to the past up to 1979 using the 2003–2009 average and applying the decreasing trend in sulfate aerosols from LMDz-OR-INCA, whose AOD trends over Europe and the Mediterranean are median among the ACCMIP models. Finally optical properties of the different aerosol types in this region are proposed from Mie calculations so that this reconstruction can be included in regional climate models for aerosol radiative forcing and aerosolclimate studies.

  7. Assessing Aerosol Mixed Layer Heights from the NASA Larc Airborne High Spectral Resolution Lidar (HSRL) during the Discover-AQ Field Campaigns

    NASA Astrophysics Data System (ADS)

    Scarino, A. J.; Ferrare, R. A.; Burton, S. P.; Hostetler, C. A.; Hair, J. W.; Rogers, R. R.; Berkoff, T.; Sawamura, P.; Collins, J. E., Jr.; Seaman, S. T.; Cook, A. L.; Harper, D. B.; Follette-Cook, M. B.; daSilva, A.; Randles, C. A.

    2014-12-01

    The first- and second-generation NASA airborne High Spectral Resolution Lidars (HSRL-1 and HSRL-2) have been deployed on board the NASA Langley Research Center King Air aircraft during the Deriving Information on Surface Conditions from Column and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field campaigns. These included deployments during July 2011 over Washington, D.C. and Baltimore, MD, during January and February 2013 over the San Joaquin Valley of California, during September 2013 over Houston, TX and during July and August 2014 over Denver, CO. Measurements of aerosol extinction, backscatter, and depolarization are available from both HSRL-1 and HSRL-2 in coordination with other participating research aircraft and ground sites. These measurements constitute a diverse data set for use in characterizing the spatial and temporal distribution of aerosols, aerosol optical thickness (AOT), as well as the mixed layer (ML) height. Analysis of the ML height at these four locations is presented, including temporal and horizontal variability and comparisons between land and water, including the Chesapeake Bay and Galveston Bay. Using the ML heights, the distribution of AOT relative to the ML heights is determined, which is relevant for assessing the long-range transport of aerosols. The ML heights are also used to help relate column AOT measurements and extinction profiles to surface PM2.5 concentrations. The HSRL ML heights are also used to evaluate the performance in simulating the temporal and spatial variability of ML heights from both chemical regional models and global forecast models.

  8. An improved whitecap timescale for sea spray aerosol production flux modeling using the discrete whitecap method

    NASA Astrophysics Data System (ADS)

    Callaghan, Adrian H.

    2013-09-01

    The discrete whitecap method (DWM) to model the sea spray aerosol (SSA) production flux explicitly requires a whitecap timescale, which up to now has only considered a whitecap decay timescale, τdecay. A reevaluation of the DWM suggests that the whitecap timescale should account for the total whitecap lifetime (τwcap), which consists of both the formation timescale (τform) and the decay timescale (timescale definitions are given in the text). Here values of τform for 552 oceanic whitecaps measured at the Martha's Vineyard Coastal Observatory on the east coast of the USA are presented, and added to the corresponding values of τdecay to form 552 whitecap timescales. For the majority of whitecaps, τform makes up about 20-25% of τwcap, but this can be as large as 70% depending on the value of τdecay. Furthermore, an area-weighted mean whitecap timescale for use in the DWM (τDWM) is defined that encompasses the variable nature of individual whitecap lifetimes within a given time period, and is calculated to be 5.3 s for this entire data set. This value is combined with previously published whitecap coverage parameterizations and estimates of SSA particle production per whitecap area to form a size-resolved SSA production flux parameterization (dF(r80)/dlog10r80). This parameterization yields integrated sea-salt mass fluxes that are largely within the range of uncertainty of recent measurements over the size range 0.029 µm < r80 < 0.580 µm. Physical factors controlling whitecap lifetime such as bubble plume lifetime and surfactant stabilization are discussed in the context of SSA production from whitecaps.

  9. Study on particulate matter air pollution in Beijing with MODIS aerosol level 2 products

    NASA Astrophysics Data System (ADS)

    Mao, Jietai; Li, Chengcai; Lau, Alexis K.

    2004-09-01

    In the run-up to the 2008 Olympic Games in Beijing, Chinese government officials at both the central and municipal levels are keenly aware that they must transform Beijing into a world-class city. According to the Beijing Municipal Environmental Protection Bureau (BJEPB) to improve its air quality some actions are adopting, including taking steps to increase the forested area surrounding the city preventing dust storms, reducing the automotive vehicles, moving polluting factories now inside the fourth ring road ringing the inner city to locations outside of the fourth ring road, and switching the fuel of public buses and taxis from diesel to natural gas, etc. Will they eliminate most serious environmental problems in Beijing? MODIS aerosol products are helping us to answer this kind of questions. A long-term validation has been finished by sun-photometer observations, and the results proved the relative error of MODIS level 2 products was slightly larger than the estimation of Chu et al. (2002) from the results in most AERONET sites. However, the comparison between the products and moisture-corrected air pollution index (API) data, which were daily released to public by EPB, showed a high correlation coefficient. An air pollution episode in 2003 was investigated by the usage of satellite products. Our conclusion for the air pollution control strategy in Beijing is that only reducing the pollution sources from inner city can't fully solve the pollution problems in Beijing and the regional transports from the nearby southern provinces are contributing a lot to the pollution situation in Beijing.

  10. Radiative Effects of Aerosols

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.

    1996-01-01

    During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size-resolved aerosol microphysics and chemistry. Both profiles included a pollution haze from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core. The soot core increased the calculated extinction by about 10% in the most polluted drier layer relative to a pure sulfate aerosol but had significantly less effect at higher humidities. A 3 km descent through a boundary layer air mass dominated by pollutant aerosol with relative humidities (RH) 10-77% yielded a close agreement between the measured and calculated aerosol optical depths (550 nm) of 0.160 (+/- 0.07) and 0. 157 (+/- 0.034) respectively. During descent the aerosol mass scattering coefficient per unit sulfate mass varied from about 5 to 16 m(exp 2)/g and primarily dependent upon ambient RH. However, the total scattering coefficient per total fine mass was far less variable at about 4+/- 0.7 m(exp 2)/g. A subsequent descent through a Saharan dust layer located above the pollution aerosol layer revealed that both layers contributed similarly to aerosol optical depth. The scattering per unit mass of the coarse aged dust was estimated at 1.1 +/- 0.2 m(exp 2)/g. The large difference (50%) in measured and calculated optical depth for the dust layer exceeded measurements.

  11. Variability of aerosol properties and Planetary Boundary Layer heights from airborne High Spectral Resolution Lidar, ground-based measurements, and the WRF model during CalNex and CARES

    NASA Astrophysics Data System (ADS)

    Obland, M. D.; Swanson, A. J.; Ferrare, R. A.; Burton, S. P.; Hair, J. W.; Hostetler, C. A.; Rogers, R.; Fast, J. D.; Berg, L. K.; Pekour, M. S.; Shaw, W. J.; Zaveri, R. A.; Haman, C. L.; Cook, A.; Harper, D.

    2011-12-01

    The NASA airborne High Spectral Resolution Lidar (HSRL) was deployed on board the NASA Langley Research Center's B200 aircraft to California in May and June of 2010 to aid in characterizing aerosol properties during the CalNex and CARES field missions. Measurements of aerosol extinction (at 532 nm), backscatter (at 532 and 1064 nm), and depolarization (at 532 and 1064 nm) during 31 flights and nearly 100 hours, many in coordination with other participating research aircraft, satellites, and ground sites, constitute a diverse data set for use in characterizing the spatial and temporal distribution of aerosols, as well as properties and variability of the Planetary Boundary Layer (PBL). This work examines the variability of the extensive (dependent on aerosol type and number density) and intensive (dependent on aerosol type only) aerosol properties to aid in describing the broader context of aerosol behavior within and nearby the Sacramento and Los Angeles Basin regions. PBL heights derived from HSRL measurements will be compared with those produced by local ceilometers, radiosondes, and the Weather Research and Forecasting (WRF) model. Spatial and temporal averages of aerosol properties will be presented.

  12. High-time resolved measurements of biogenic and anthropogenic secondary organic aerosol precursors and products in urban air

    NASA Astrophysics Data System (ADS)

    Flores, Rosa M.; Doskey, Paul V.

    2016-04-01

    Volatile organic compounds (VOCs), which are present in the atmosphere entirely in the gas phase are directly emitted by biogenic (~1089 Tg yr-1) and anthropogenic sources (~185 Tg yr-1). However, the sources and molecular speciation of intermediate VOCs (IVOCs), which are for the most part also present almost entirely in the gas phase, are not well characterized. The VOCs and IVOCs participate in reactions that form ozone and semivolatile OC (SVOC) that partition into the aerosol phase. Formation and evolution of secondary organic aerosol (SOA) are part of a complex dynamic process that depends on the molecular speciation and concentration of VOCs, IVOCs, primary organic aerosol (POA), and the level of oxidants (NO3, OH, O3). The current lack of understanding of OA properties and their impact on radiative forcing, ecosystems, and human health is partly due to limitations of models to predict SOA production on local, regional, and global scales. More accurate forecasting of SOA production requires high-temporal resolution measurement and molecular characterization of SOA precursors and products. For the subject study, the IVOCs and aerosol-phase organic matter were collected using the high-volume sampling technique and were analyzed by multidimensional gas chromatography with time-of-flight mass spectrometry (GCxGC-ToFMS). The IVOCs included terpenes, terpenoids, n-alkanes, branched alkanes, isoprenoids, alkylbenzenes, cycloalkylbenzenes, PAH, alkyl PAH, and an unresolved complex mixture (UCM). Diurnal variations of OA species containing multiple oxygenated functionalities and selected SOA tracers of isorprene, α-pinene, toluene, cyclohexene, and n-dodecane oxidation were also quantified. The data for SOA precursor and oxidation products presented here will be useful for evaluating the ability of molecular-specific SOA models to forecast SOA production in and downwind of urban areas.

  13. Comparison Between NPP-VIIRS Aerosol Data Products and the MODIS AQUA Deep Blue Collection 6 Dataset Over Land

    NASA Technical Reports Server (NTRS)

    Sayer, Andrew M.; Hsu, N. C.; Bettenhausen, C.; Lee, J.; Kondragunta, S.

    2013-01-01

    Aerosols are small particles suspended in the atmosphere and have a variety of natural and man-made sources. Knowledge of aerosol optical depth (AOD), which is a measure of the amount of aerosol in the atmosphere, and its change over time, is important for multiple reasons. These include climate change, air quality (pollution) monitoring, monitoring hazards such as dust storms and volcanic ash, monitoring smoke from biomass burning, determining potential energy yields from solar plants, determining visibility at sea, estimating fertilization of oceans and rainforests by transported mineral dust, understanding changes in weather brought upon by the interaction of aerosols and clouds, and more. The Suomi-NPP satellite was launched late in 2011. The Visible Infrared Imaging Radiometer Suite (VIIRS) aboard Suomi-NPP is being used, among other things, to determine AOD. This study compares the VIIRS dataset to ground-based measurements of AOD, along with a state-of-the-art satellite AOD dataset (the new version of the Moderate Resolution Imaging Spectrometer Deep Blue algorithm) to assess its reliability. The Suomi-NPP satellite was launched late in 2011, carrying several instruments designed to continue the biogeophysical data records of current and previous satellite sensors. The Visible Infrared Imaging Radiometer Suite (VIIRS) aboard Suomi-NPP is being used, among other things, to determine aerosol optical depth (AOD), and related activities since launch have been focused towards validating and understanding this new dataset through comparisons with other satellite and ground-based products. The operational VIIRS AOD product is compared over land with AOD derived from Moderate Resolution Imaging Spectrometer (MODIS) observations using the Deep Blue (DB) algorithm from the forthcoming Collection 6 of MODIS data

  14. A Spatio-Temporal Approach for Global Validation and Analysis of MODIS Aerosol Products

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles; Chu, D. Allen; Mattoo, Shana; Kaufman, Yoram J.; Remer, Lorraine A.; Tanre, Didier; Slutsker, Ilya; Holben, Brent N.; Lau, William K. M. (Technical Monitor)

    2001-01-01

    With the launch of the MODIS sensor on the Terra spacecraft, new data sets of the global distribution and properties of aerosol are being retrieved, and need to be validated and analyzed. A system has been put in place to generate spatial statistics (mean, standard deviation, direction and rate of spatial variation, and spatial correlation coefficient) of the MODIS aerosol parameters over more than 100 validation sites spread around the globe. Corresponding statistics are also computed from temporal subsets of AERONET-derived aerosol data. The means and standard deviations of identical parameters from MOMS and AERONET are compared. Although, their means compare favorably, their standard deviations reveal some influence of surface effects on the MODIS aerosol retrievals over land, especially at low aerosol loading. The direction and rate of spatial variation from MODIS are used to study the spatial distribution of aerosols at various locations either individually or comparatively. This paper introduces the methodology for generating and analyzing the data sets used by the two MODIS aerosol validation papers in this issue.

  15. Observation of rates and products in the reaction of NO3 with submicron squalane and squalene aerosol.

    PubMed

    Lee, Lance; Wooldridge, Paul; Nah, Theodora; Wilson, Kevin; Cohen, Ronald

    2013-01-21

    The reactive uptake coefficients γ, for nitrate radical, NO(3), on ∼100 nm diameter squalane and squalene aerosol were measured (1 atm pressure of N(2) and 293 K). For squalane, a branched alkane, γ(NO(3)) of 2.8 × 10(-3) was estimated. For squalene which contains 6 double bonds, γ(NO(3)) was found to be a function of degree of oxidation with an initial value of 0.18 ± 0.03 on fresh particles increasing to 0.82 ± 0.11 on average of over 3 NO(3) reactions per squalene molecule in the aerosol. Synchrotron VUV-ionization aerosol mass spectrometry was used to detect the particle phase oxidation products that include as many as 3 NO(3) subunits added to the squalene backbone. The fraction of squalene remaining in the aerosol follows first order kinetics under oxidation, even at very high oxidation equivalents, which suggests that the matrix remains a liquid upon oxidation. Our calculation indicates a much shorter chemical lifetime for squalene-like particle with respect to NO(3) than its atmospheric lifetime to deposition or wet removal.

  16. The Remote Sensing of Mineral Aerosols and Their Impact on Phytoplankton Productivity using Sea WiFS

    NASA Technical Reports Server (NTRS)

    Stegmann, Petra M.

    1998-01-01

    The main objective of this proposal was to use SeaWiFs data to study the relationship between aerosols found in aeollan dust and photosynthesis of phytoplankton in open ocean surface waters. This project was a collaborative effort between myself and Dr. Neil Tindale at Texas A&M University and followed on our earlier funded proposal which had been designed as a proof-of-concept study to determine if ocean color sensors such as the Coastal Zone Color Scanner (CZCS) could be used to detect and map large-scale mineral aerosol plumes. Despite the large spatial and temporal gaps inherent in the CZCS data coverage, our results from this initial study indicated that an ocean color sensor could indeed be used to detect aerosols. These encouraging results led us to propose in this proposal the use of SeaWiFS data to study mineral aerosol transport and its impact on phytoplankton production. This proposal orignally intended to make use of SeaWiFS images, but as the launch delay of SeaWiFS dragged on, we had to make do with other satellite data sets. Thus, the focus of this proposal became the CSCS image archive instead. I detail my results and accomplishments with this data set.

  17. The quantitative determination of aspirin and its degradation products in a model solution aerosol.

    PubMed

    Blondino, F E; Byron, P R

    1995-02-01

    Formulation of pressurized aerosol solutions in propellants for inhalation requires the use of high quantities of surfactants to solubilize the drug. Due to the lipophilic nature of these surfactants, analytical difficulties are created for those wishing to quantify the drug and its degradation products. In order to quantify drug and degradation products by LC it is necessary to separate surfactant and analytes prior to chromatography. To illustrate a typical situation, a method was developed for the analysis of acetylsalicyclic acid (approximately 2.5 x 10(-3) M) and its major degradation products (salicylic acid, acetylsalicylsalicylic acid and salicylsalicylic acid) solubilized in trichloromonofluoromethane (CFC-11) containing 10(-2) M sorbitan trioleate (Span 85). Surfactant extraction problems were reviewed experimentally. The presentation of all analytes and the surfactant, dissolved in hexane, to silica solid phase extraction columns, followed by elution in a polar solvent, was found to be an efficient way of separating this lipophilic surfactant from the analytes. The final assay employed propellant evaporation, reconstitution of the non-volatiles in hexane, normal phase solid phase extraction (recoveries of 100 +/- 10% were observed for all analytes), elution and dilution with mobile phase, and reversed-phase liquid chromatography (Econosphere C8 5 microns, 4.6 x 250 mm). The assay utilized a mobile phase of water, methanol, tetrahydrofuran and 1 M phosphoric acid with ultraviolet detection at 275 nm. Using external standards, linear calibration curves of peak height versus concentration were obtained for all analytes in the expected concentration ranges (r > 0.991). As it is described, the assay had a relative standard deviation of < or = 3.7% for all analytes.

  18. Aerosol Radiative Forcing Estimates from South Asian Clay Brick Production Based on Direct Emission Measurements

    NASA Astrophysics Data System (ADS)

    Weyant, C.; Athalye, V.; Ragavan, S.; Rajarathnam, U.; Kr, B.; Lalchandani, D.; Maithel, S.; Malhotra, G.; Bhanware, P.; Thoa, V.; Phuong, N.; Baum, E.; Bond, T. C.

    2012-12-01

    About 150-200 billion clay bricks are produced in India every year. Most of these bricks are fired in small-scale traditional kilns that burn coal or biomass without pollution controls. Reddy and Venkataraman (2001) estimated that 8% of fossil fuel related PM2.5 emissions and 23% of black carbon emissions in India are released from brick production. Few direct emissions measurements have been done in this industry and black carbon emissions, in particular, have not been previously measured. In this study, 9 kilns representing five common brick kiln technologies were tested for aerosol properties and gaseous pollutant emissions, including optical scattering and absorption and thermal-optical OC/EC. Simple relationships are then used to estimate the radiative-forcing impact. Kiln design and fuel quality greatly affect the overall emission profiles and relative climate warming. Batch production kilns, such as the Downdraft kiln, produce the most PM2.5 (0.97 gPM2.5/fired brick) with an OC/EC fraction of 0.3. Vertical Shaft Brick kilns using internally mixed fuels produce the least PM (0.09 gPM2.5/kg fired brick) with the least EC (OC/EC = 16.5), but these kilns are expensive to implement and their use throughout Southern Asia is minimal. The most popular kiln in India, the Bull's Trench kiln, had fewer emissions per brick than the Downdraft kiln, but an even higher EC fraction (OC/EC = 0.05). The Zig-zag kiln is similar in structure to the Bull's Trench kiln, but the emission factors are significantly lower: 50% reduction for CO, 17% for PM2.5 and 60% for black carbon. This difference in emissions suggests that converting traditional Bull's Trench kilns into less polluting Zig-zag kilns would result in reduced atmospheric warming from brick production.

  19. Preliminary results for salt aerosol production intended for marine cloud brightening, using effervescent spray atomization

    PubMed Central

    Cooper, Gary; Foster, Jack; Galbraith, Lee; Jain, Sudhanshu; Neukermans, Armand; Ormond, Bob

    2014-01-01

    The large-scale production of vast numbers of suitable salt nuclei and their upward launch is one of the main technological barriers to the experimental testing of marine cloud brightening (MCB). Very promising, though not definitive, results have been obtained using an adapted version of effervescent spray atomization. The process is simple, robust and inexpensive. This form of effervescent spraying uses only pressurized water and air sprayed from small nozzles to obtain very fine distributions. While it is far from optimized, and may not be the best method if full deployment is ever desired, we believe that even in its present form the process would lend itself well to preliminary field test investigations of MCB. Measurements obtained using standard aerosol instrumentation show approximately lognormal distributions of salt nuclei with median diameters of approximately 65 nm and geometric standard deviations slightly less than 2. However, these measurements are not in agreement with those based on scanning electron microscopy imaging of collected particles, an observation that has not yet been explained. Assuming the above distribution, 1015 particles per second could be made with 21 kW of spray power, using approximately 200 nozzles. It is envisioned that existing snow making equipment can be adapted to launch the nuclei 60–100 m into the air, requiring approximately 20 kW of additional power. PMID:25404673

  20. The generation of aerosols by accidents which may occur during plant-scale production of micro-organisms.

    PubMed Central

    Ashcroft, J.; Pomeroy, N. P.

    1983-01-01

    Experiments have been performed to simulate accidents which may occur during large-scale production of micro-organisms. Four types of accident, which were considered to be the most likely to result in the greatest hazard to health, were simulated using a bacterial model. The accidents were all concerned with faults occurring in the operation of the microbial fermenter. Gross contamination of surfaces occurred in all experiments, but only three types of accident produced a measurable aerosol. PMID:6350448

  1. Aerosol and product yields from NO{sub 3} radical-initiated oxidation o/f selected monoterpenes

    SciTech Connect

    Hallquist, M.; Ljungstroem, E.; Waengberg, I.; Barnes, I.; Becker, K.H.

    1999-02-15

    Atmospheric transformation of monoterpenes gives products that may cause environmental consequences. In this work the NO{sub 3} radical-initiated oxidation of the monoterpenes {alpha}-pinene, {beta}-pinene, {Delta}{sup 3}-carene, and limonene has been investigated. All experiments were conducted in EUPHORE, the EUropean PHOto REactor facility in Valencia, Spain. The aerosol and product yields were measured in experiments with a conversion of the terpenes in the interval from 7 to 400 ppb. The lower end of the concentrations used are close to those measured in ambient pine forest air. Products were measured using long path in situ FTIR. Aerosol yields were obtained using a DMA-CPC system. The aerosol mass yields measured at low concentrations were <1, 10, 15, and 17% for {alpha}-pinene, {beta}-pinene, {Delta}{sup 3}-carene, and limonene, respectively. The total molar alkylnitrate yields were calculated to be 19, 61, 66, and 48%, and molar carbonyl compound yields were estimated to be 71, 14, 29, and 69% for {alpha}-pinene, {beta}-pinene, {Delta}{sup 3}-carene, and limonene, respectively. The aerosol yields were strongly dependent on the amounts of terpene reacted, whereas the nitrate and carbonyl yields do not depend on the amount of terpene converted. The principal carbonyl compound from {alpha}pinene oxidation was pinonaldehyde. In the case of limonene, endolim was tentatively identified and appears to be a major product. The reactions with {beta}-pinene and {Delta}{sup 3}-carene yielded 1--2% of nopinone and 2--3% caronaldehyde, respectively. The results show that it is not possible to use generalized descriptions of terpene chemistry, e.g., in mathematical models.

  2. The Impact of Monthly Variation of the Pacific-North America (PNA) Teleconnection Pattern on Wintertime Surface-layer Aerosol Concentrations in the United States

    NASA Astrophysics Data System (ADS)

    Feng, J.; Liao, H.; Li, J.

    2015-12-01

    The Pacific-North America teleconnection (PNA) is the leading general circulation pattern in the troposphere over the region of North Pacific to North America during wintertime. The PNA exhibits positive (negative) phases with positive (negative) anomalies in geopotential height in the vicinity of Hawaii and over the intermountain region of North America, and negative (positive) anomalies in geopotential height over south of the Aleutian Islands and the Gulf Coast region of the United States. This study examined the impacts of monthly variation of the PNA phase on wintertime surface-layer aerosol concentrations in the United States by analyzing observations during 1999-2013 from the Air Quality System of Environmental Protection Agency (EPA-AQS) and the model results for 1986-2006 from the global three-dimensional Goddard Earth Observing System (GEOS) chemical transport model (GEOS-Chem). The composite analyses on the EPA-AQS observations over 1999-2003 showed that the average PM2.5 concentrations were higher in the PNA positive phases than in the PNA negative phases by 1.0 μg m-3 (8.6%), 2.1μg m-3 (24.1%), and 1.1 μg m-3 (10.6%) in the eastern, western, and whole of United States, respectively. Relative to the PNA negative phases, the number of exceedance days (days with the PM2.5 concentrations exceeding 35 μg m-3) in the PNA positive phases increased by 5-8 days month-1 in California and the contiguous Great Salt Lake and by 2-3 days month-1 in Iowa. The simulated geographical patterns of the differences in concentrations of PM2.5, nitrate, sulfate, ammonium, OC, and BC between the PNA positive and negative phases were similar to observations. The PNA influences surface-layer aerosol concentrations in the United States by changing meteorological variables such as temperature, precipitation, planetary boundary layer height, relative humidity, and wind speed. We found that that the PNA-induced variation in planetary boundary layer height was the most dominant

  3. Quality and compatibility analyses of global aerosol products derived from the advanced very high resolution radiometer and Moderate Resolution Imaging Spectroradiometer

    NASA Astrophysics Data System (ADS)

    Jeong, Myeong-Jae; Li, Zhanqing; Chu, D. Allen; Tsay, Si-Chee

    2005-05-01

    There exist numerous global aerosol products derived from various satellite sensors, but little insight has been gained about their compatibility and quality. This study presents a comparison of two prominent global aerosol products derived over oceans from the advanced very high resolution radiometer (AVHRR) under the Global Aerosol Climatology Project (GACP) (Mishchenko et al., 1999) and the Moderate Resolution Imaging Spectroradiometer (MODIS) (Tanré et al., 1997). The comparisons are for monthly mean aerosol optical thickness (AOT) and Ångström exponent (α) at a spatial resolution of 1 × 1 degree. The two monthly AOT products showed substantial discrepancies, with a tendency of higher values from MODIS than from GACP/AVHRR, especially near the coasts of major aerosol outbreak regions. Individual monthly AOT values have poor correlation, but their regional means are moderately correlated (correlation coefficient 0.5 < R < 1.0). While cloud screening has often been argued to be a major factor explaining large discrepancies, this study shows that differences in aerosol models in the two retrieval algorithms can lead to large discrepancies. Contributions of the size distribution are more significant than the refractive index. The noisiness of the GACP/AVHRR aerosol retrievals seem to be partially influenced by radiometric uncertainties in the AVHRR system, but it is unlikely a major factor to explain the observed systematic discrepancies between the MODIS and GACP/AVHRR AOTs. For α, correlations between MODIS and GACP/AVHRR are lower (0.2 < R < 0.7) than AOT. The MODIS α shows a well-behaved dependence on the AOT contingent upon the aerosol type, while the GACP/AVHRR α has little correlation with the AOT. The high sensitivity in the selection of aerosol models to radiometric errors may be a primary reason for the worse comparison of α. Part of the discrepancies in α is attributed to different aerosol size distributions.

  4. Study of a CCP RF Dusty Plasma for the Production of Titan's Aerosols Analogues

    SciTech Connect

    Alcouffe, G.; Cernogora, G.; Ouni, F.; Correia, J. J.; Cavarroc, M.; Boufendi, L.; Szopa, C.

    2008-09-07

    The CCP-RF discharge PAMPRE experiment produces analogues of Titan's aerosols. Here are presented the plasma characteristics as a function of gas mixtures and dust formation. Electronic density, optical emission spectroscopy, and self-bias voltage measurements are presented.

  5. Variability of CCN Activation Behaviour of Aerosol Particles in the Marine Boundary Layer of the Northern and Southern Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Henning, Silvia; Dieckmann, Katrin; Hartmann, Susan; Schäfer, Michael; Wu, Zhijun; Merkel, Maik; Wiedensohler, Alfred; Stratmann, Frank

    2013-04-01

    The variability of cloud condensation nucleus (CCN) activation behaviour and total CCN number concentrations was investigated during three ship cruises. Measurements were performed in a mobile laboratory on the German research vessel FS Polarstern cruising between Cape Town and Bremerhaven (April / May and October / November 2011) as well as between Punta Arenas and Bremerhaven (April / May 2012). CCN size distributions were measured for supersaturations between 0.1% and 0.4% using a Cloud Condensation Nucleus Counter (DMT, USA). Aerosol particle and CCN total number concentrations as well as the hygroscopicity parameter κ (Petters and Kreidenweis, 2007) were determined. Furthermore, size distribution data were collected. The hygroscopicity parameter κ featured a high variability during the cruises, with a median κ-value of 0.52 ± 0.26. The κ-values are depended on air mass origin; and are as expected mainly dominated by marine influences, but also long range transport of aerosol particles was detected. In the Celtic Sea, κ was found to be lower than that of clean marine aerosol particles (0.72 ± 0.24; Pringle et al., 2010) with κ-values ~0.2, possibly influenced by anthropogenic emissions from Europe. Close to the West African coast particle hygroscopicity was found to be influenced by the Saharan dust plume, resulting in low κ-values ~0.25. Petters, M.D. and S.M. Kreidenweis (2007), A single parameter representation of hygroscopic growth and cloud condensation nucleus activity, Atmos. Chem. and Phys., 7, 1961-1971. Pringle, K.J., H. Tost, A. Pozzer, U. Pöschl, and J. Lelieveld (2010), Global distribution of the effective aerosol hygroscopicity parameter for CCN activation, Atmos. Chem. Phys., 10, 5241-5255.

  6. Mass-analysis of Charged Aerosol Particles in a PMSE/NLC Layer by a Rocket-borne Spectrometer

    NASA Astrophysics Data System (ADS)

    Robertson, Scott; Knappmiller, Scott; Horanyi, Mihaly; Sternovsky, Zoltan; Baumgarten, Gerd; Latteck, Ralph; Rapp, Markus; Holzworth, Robert; Shimogawa, Michael; Gumbel, Jorg; Megner, Ms Linda; Friedrich, Martin

    Two "MASS" rockets (Mesospheric Aerosol Sampling Spectrometer) were launched from the Andoya Rocket Range (Norway) the first week of August 2007. The payloads carried an electrostatic mass analyzer for the charged fraction of the aerosol particles, electric field booms, a photometer for cloud brightness, and Faraday rotation antennas for electron density. Aerosol particles with different ranges of charge-to-mass ratio were collected within the instrument housing on two sets of four biased collector plates, with one set for positive particles and one set for negative particles. The first rocket was launched into PMSE and NLC on 3 August. The sun was 4 degrees below the horizon and NLC were seen in the previous hour at 83 km by the ALOMAR RMR lidar. NLC were detected at the same altitude by rocket-borne photometer measurements. The charged aerosol data shows the density of negative particles with radius greater than 3 nm rising sharply at 83 km and continuing to 89 km, collocated with PMSE detected by the ALWIN radar. Particles with 1-2 nm radii with both signs of charge and particles with less than 1 nm radius charged positively were detected at 86-88 km. The occurrence of the positive particles in the smallest size range in the region of lowest temperature suggests that their origin is nucleation and growth on ions. Initial charge-density estimates are several thousands per cubic centimeter for each of these size ranges. The second launch was 6 August into PMSE without NLC. The 1-2 nm particles were seen from 85.4 to 87.4 km, again with both signs of charge. Larger sizes were nearly absent.

  7. Ice nucleating particles at a coastal marine boundary layer site: correlations with aerosol type and meteorological conditions

    NASA Astrophysics Data System (ADS)

    Mason, R. H.; Si, M.; Li, J.; Chou, C.; Dickie, R.; Toom-Sauntry, D.; Pöhlker, C.; Yakobi-Hancock, J. D.; Ladino, L. A.; Jones, K.; Leaitch, W. R.; Schiller, C. L.; Abbatt, J. P. D.; Huffman, J. A.; Bertram, A. K.

    2015-11-01

    Information on what aerosol particle types are the major sources of ice nucleating particles (INPs) in the atmosphere is needed for climate predictions. To determine which aerosol particles are the major sources of immersion-mode INPs at a coastal site in Western Canada, we investigated correlations between INP number concentrations and both concentrations of different atmospheric particles and meteorological conditions. We show that INP number concentrations are strongly correlated with the number concentrations of fluorescent bioparticles between -15 and -25 °C, and that the size distribution of INPs is most consistent with the size distribution of fluorescent bioparticles. We conclude that biological particles were likely the major source of ice nuclei at freezing temperatures between -15 and -25 °C at this site for the time period studied. At -30 °C, INP number concentrations are also well correlated with number concentrations of the total aerosol particles ≥ 0.5 μm, suggesting that non-biological particles may have an important contribution to the population of INPs active at this temperature. As we found that black carbon particles were unlikely to be a major source of ice nuclei during this study, these non-biological INPs may include mineral dust. Furthermore, correlations involving chemical tracers of marine aerosols and marine biological activity, sodium and methanesulfonic acid, indicate that the majority of INPs measured at the coastal site likely originated from terrestrial rather than marine sources. Finally, six existing empirical parameterizations of ice nucleation were tested to determine if they accurately predict the measured INP number concentrations. We found that none of the parameterizations selected are capable of predicting INP number concentrations with high accuracy over the entire temperature range investigated. This finding illustrates that additional measurements are needed to improve parameterizations of INPs and their

  8. Operational Retrieval of aerosol optical depth over Indian subcontinent and Indian Ocean using INSAT-3D/Imager product validation

    NASA Astrophysics Data System (ADS)

    Mishra, M. K.; Rastogi, G.; Chauhan, P.

    2014-11-01

    Aerosol optical depth (AOD) over Indian subcontinent and Indian Ocean region is derived operationally for the first time from the geostationary earth orbit (GEO) satellite INSAT-3D Imager data at 0.65 μm wavelength. Single visible channel algorithm based on clear sky composites gives larger retrieval error in AOD than other multiple channel algorithms due to errors in estimating surface reflectance and atmospheric property. However, since MIR channel signal is insensitive to the presence of most aerosols, therefore in present study, AOD retrieval algorithm employs both visible (centred at 0.65 μm) and mid-infrared (MIR) band (centred at 3.9 μm) measurements, and allows us to monitor transport of aerosols at higher temporal resolution. Comparisons made between INSAT-3D derived AOD (τI) and MODIS derived AOD (τM) co-located in space (at 1° resolution) and time during January, February and March (JFM) 2014 encompasses 1165, 1052 and 900 pixels, respectively. Good agreement found between τI and τM during JFM 2014 with linear correlation coefficients (R) of 0.87, 0.81 and 0.76, respectively. The extensive validation made during JFM 2014 encompasses 215 co-located AOD in space and time derived by INSAT 3D (τI) and 10 sun-photometers (τA) that includes 9 AERONET (Aerosol Robotic Network) and 1 handheld sun-photometer site. INSAT-3D derived AOD i.e. τI, is found within the retrieval errors of τI = ±0.07 ±0.15τA with linear correlation coefficient (R) of 0.90 and root mean square error equal (RMSE) to 0.06. Present work shows that INSAT-3D aerosol products can be used quantitatively in many applications with caution for possible residual clouds, snow/ice, and water contamination.

  9. The impact of monthly variation of the Pacific-North America (PNA) teleconnection pattern on wintertime surface-layer aerosol concentrations in the United States

    NASA Astrophysics Data System (ADS)

    Feng, Jin; Liao, Hong; Li, Jianping

    2016-04-01

    The Pacific-North America teleconnection (PNA) is the leading general circulation pattern in the troposphere over the region of North Pacific to North America during wintertime. This study examined the impacts of monthly variations of the PNA phase (positive or negative phase) on wintertime surface-layer aerosol concentrations in the United States (US) by analyzing observations during 1999-2013 from the Air Quality System of the Environmental Protection Agency (EPA-AQS) and the model results for 1986-2006 from the global three-dimensional Goddard Earth Observing System (GEOS) chemical transport model (GEOS-Chem). The composite analyses on the EPA-AQS observations over 1999-2013 showed that the average concentrations of PM2.5, sulfate, nitrate, ammonium, organic carbon, and black carbon aerosols over the US were higher in the PNA positive phases (25 % of the winter months examined, and this fraction of months had the highest positive PNA index values) than in the PNA negative phases (25 % of the winter months examined, and this fraction of months had the highest negative PNA index values) by 1.0 µg m-3 (8.7 %), 0.01 µg m-3 (0.5 %), 0.3 µg m-3 (29.1 %), 0.1 µg m-3 (11.9 %), 0.6 µg m-3 (13.5 %), and 0.2 µg m-3 (27.8 %), respectively. The simulated geographical patterns of the differences in concentrations of all aerosol species between the PNA positive and negative phases were similar to observations. Based on the GEOS-Chem simulation, the pattern correlation coefficients were calculated to show the impacts of PNA-induced variations in meteorological fields on aerosol concentrations. The PNA phase was found (i) to influence sulfate concentrations mainly through changes in planetary boundary layer height (PBLH), precipitation (PR), and temperature; (ii) to influence nitrate concentrations mainly through changes in temperature; and (iii) to influence concentrations of ammonium, organic carbon, and black carbon mainly through changes in PR and PBLH. Results from

  10. Activation of the Solid Silica Layer of Aerosol-Based C/SiO₂ Particles for Preparation of Various Functional Multishelled Hollow Microspheres.

    PubMed

    Li, Xiangcun; Luo, Fan; He, Gaohong

    2015-05-12

    Double-shelled C/SiO2 hollow microspheres with an outer nanosheet-like silica shell and an inner carbon shell were reported. C/SiO2 aerosol particles were synthesized first by a one-step rapid aerosol process. Then the solid silica layer of the aerosol particles was dissolved and regrown on the carbon surface to obtain novel C/SiO2 double-shelled hollow microspheres. The new microspheres prepared by the facile approach possess high surface area and pore volume (226.3 m(2) g(-1), 0.51 cm(3) g(-1)) compared with the original aerosol particles (64.3 m(2) g(-1), 0.176 cm(3) g(-1)), providing its enhanced enzyme loading capacity. The nanosheet-like silica shell of the hollow microspheres favors the fixation of Au NPs (C/SiO2/Au) and prevents them from growing and migrating at 500 °C. Novel C/C and C/Au/C (C/Pt/C) hollow microspheres were also prepared based on the hollow nanostructure. C/C microspheres (482.0 m(2) g(-1), 0.92 cm(3) g(-1)) were ideal electrode materials. In particular, the Au NPs embedded into the two carbon layers (C/Au/C, 431.2 m(2) g(-1), 0.774 cm(3) g(-1)) show a high catalytic activity and extremely chemical stability even at 850 °C. Moreover, C/SiO2/Au, C/Au/C microspheres can be easily recycled and reused by an external magnetic field because of the presence of Fe3O4 species in the inner carbon shell. The synthetic route reported here is expected to simplify the fabrication process of double-shelled or yolk-shell microspheres, which usually entails multiple steps and a previously synthesized hard template. Such a capability can facilitate the preparation of various functional hollow microspheres by interfacial design.

  11. Tropospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Buseck, P. R.; Schwartz, S. E.

    2003-12-01

    within the atmosphere. Therefore, the few existing approaches to chemical transformation and aerosol evolution rest heavily on assumptions, for example, that particles are adequately represented as spheres and are homogeneous in composition as a function of particle size, although both assumptions are known to be inaccurate (e.g., Buseck and Pósfai, 1999; Buseck et al., 2002).This chapter provides an overview of the loading, geographical distribution, and chemical and physical properties of both natural and anthropogenic atmospheric aerosols and of the processes controlling their production, reaction, transport, and ultimate removal - the "life cycle" of tropospheric aerosols. More detailed treatment may be found in texts by Junge (1963), Friedlander (1977), Twomey (1977), Hinds (1982, 1999), Seinfeld and Pandis (1998), and Jacob (1999). We highlight here the effects of aerosols on climate. The effects of aerosols on health, visibility, heterogeneous chemistry, and ozone are examined by Heintzenberg et al. (2003), Jacob (2000), Kreidenweis (1995), Anastasio and Martin (2001), Pósfai and Molnár (2000), and Prospero et al. (2002). A detailed overview of tropospheric aerosols and their environmental effects is given by EPA (2002). Kaufman et al. (2002) provide an overview of satellite measurement of aerosols pertinent to climate change.

  12. Blowing Snow - A Major Source of Aerosol in the Polar Regions?

    NASA Astrophysics Data System (ADS)

    Kalnajs, L.; DeCarlo, P. F.; Giordano, M.; Davis, S. M.; Deshler, T.; Johnson, A.; Goetz, J. D.; Mukherjee, A. D.; Slater, A. G.

    2015-12-01

    Sea salt aerosol is the dominant aerosol component in unpolluted Polar Regions, particularly in the sea ice zone. In the lower latitude liquid ocean, wave action and bubble bursting is thought to be the main mechanism for sea salt aerosol production. However there is growing evidence that in the Polar Regions, particularly near sea ice, that the sublimation of wind lofted salty snow may be a dominant source of sea salt aerosol. An extensive set of aerosol sizing and compositional measurements was made at sea ice location near Ross Island, Antarctica during two field measurement campaigns - a summer campaign in 2014 and late winter campaign in 2015. Sizing measurements from both open and closed path aerosol instruments, and compositional measurements from an Aerosol Mass Spectrometer suggest that there is a significant enhancement in both super and sub micron aerosol associated with high wind events and blowing snow in the boundary layer. While the composition of this aerosol indicates that it is primarily of marine origin, the ratios of the major sea salt ions suggest that processing in the snow pack significantly modifies the aerosol. This alternate sea salt aerosol production mechanism could have significant impact on the modeling of tropospheric halogen chemistry and on the interpretation of sea salt-based proxies in the ice core record.

  13. Comparison of ground based indices (API and AQI) with satellite based aerosol products.

    PubMed

    Zheng, Sheng; Cao, Chun-Xiang; Singh, Ramesh P

    2014-08-01

    Air quality in mega cities is one of the major concerns due to serious health issues and its indirect impact to the climate. Among mega cities, Beijing city is considered as one of the densely populated cities with extremely poor air quality. The meteorological parameters (wind, surface temperature, air temperature and relative humidity) control the dynamics and dispersion of air pollution. China National Environmental Monitoring Centre (CNEMC) started air pollution index (API) as of 2000 to evaluate air quality, but over the years, it was felt that the air quality is not well represented by API. Recently, the Ministry of Environmental Protection (MEP) of the People's Republic of China (PRC) started using a new index "air quality index (AQI)" from January 2013. We have compared API and AQI with three different MODIS (MODIS - Moderate Resolution Imaging SpectroRadiometer, onboard the Terra/Aqua satellites) AOD (aerosol optical depth) products for ten months, January-October, 2013. The correlation between AQI and Aqua Deep Blue AOD was found to be reasonably good as compared with API, mainly due to inclusion of PM2.5 in the calculation of AQI. In addition, for every month, the correlation coefficient between AQI and Aqua Deep Blue AOD was found to be relatively higher in the month of February to May. According to the monthly average distribution of precipitation, temperature, and PM10, the air quality in the months of June-September was better as compared to those in the months of February-May. AQI and Aqua Deep Blue AOD show highly polluted days associated with dust event, representing true air quality of Beijing.

  14. Chemical characterization of the main secondary organic aerosol (SOA) products formed through aqueous-phase photonitration of guaiacol

    NASA Astrophysics Data System (ADS)

    Kitanovski, Z.; Čusak, A.; Grgić, I.; Claeys, M.

    2014-04-01

    Guaiacol (2-methoxyphenol) and its derivatives can be emitted into the atmosphere by thermal degradation (i.e. burning) of wood lignins. Due to its volatility, guaiacol is predominantly distributed in the atmospheric gaseous phase. Recent studies have shown the importance of aqueous-phase reactions in addition to the dominant gas-phase and heterogeneous reactions of guaiacol, in the formation of secondary organic aerosol (SOA) in the atmosphere. The main objectives of the present study were to chemically characterize the low-volatility SOA products of the aqueous-phase photonitration of guaiacol and examine their possible presence in urban atmospheric aerosols. The aqueous-phase reactions were carried out under simulated sunlight and in the presence of H2O2 and nitrite. The formed guaiacol reaction products were concentrated by using solid-phase extraction (SPE) and then purified by means of semi-preparative high-performance liquid chromatography (HPLC). The fractionated individual compounds were isolated as pure solids and further analyzed with liquid-state 1H, 13C and 2D nuclear magnetic resonance (NMR) spectroscopy and direct infusion negative ion electrospray ionization tandem mass spectrometry ((-)ESI-MS/MS). The NMR and product ion (MS2) spectra were used for unambiguous product structure elucidation. The main products of guaiacol photonitration are 4-nitroguaiacol (4NG), 6-nitroguaiacol (6NG), and 4,6-dinitroguaiacol (4,6DNG). Using the isolated compounds as standards, 4NG and 4,6DNG were unambiguously identified in winter PM10 aerosols from the city of Ljubljana (Slovenia) by means of HPLC/(-)ESI-MS/MS. Owing to the strong absorption of UV and visible light, 4,6DNG could be an important constituent of atmospheric "brown" carbon, especially in regions affected by biomass burning.

  15. Aerosol products, mechanisms, and kinetics of heterogeneous reactions of ozone with oleic acid in pure and mixed particles.

    PubMed

    Ziemann, Paul J

    2005-01-01

    Reactions of O3 with pure and mixed oleic acid particles and bulk solutions were investigated using a thermal desorption particle beam mass spectrometer. The results provide information on the effect of particle matrix on reaction products, mechanisms, and kinetics. The major aerosol products are alpha-acyloxyalkyl hydroperoxides, secondary ozonides, alpha-alkoxyalkyl hydroperoxides, and oxocarboxylic acids formed primarily through reactions of Criegee intermediates with products or with particle matrix compounds. For example, it is estimated that for the reaction of pure oleic acid particles with O3 the aerosol products consist of approximately 68% organic peroxides, 28% 9-oxononanoic acid, and 4% azelaic acid. Although the reaction rate of pure oleic acid particles corresponds to an atmospheric lifetime of minutes, reactions in liquid/solid particle matrices can be orders of magnitude slower. The peroxide products are relatively stable when exposed to matrices typical of atmospheric particles, indicating that the lifetimes of these compounds in the atmosphere may be long enough to allow for long-range transport.

  16. A High-Spatial-Resolution, Localized MODIS Aerosol Optical Depth Product for Use in Air Quality Exposure Assessment During Large Wildfire Smoke Events

    NASA Astrophysics Data System (ADS)

    McCarthy, M. C.; Raffuse, S. M.; DeWinter, J. L.; Craig, K. J.; Jumbam, L. K.; Fruin, S.; Lurmann, F.

    2011-12-01

    Aerosol optical depth (AOD) has potential use for determining the intra-urban variability of airborne particulate matter exposure during wildfire events; however, the standard Moderate Resolution Imaging Spectroradiometer (MODIS) AOD products have limitations for this application. Specifically, the 10x10 km resolution is too coarse for intra-urban population exposure assessments, the assumed aerosol optical properties are not representative of biomass burning aerosol, and the cloud masking algorithm misinterprets heavy smoke as clouds. We developed a localized MODIS AOD product at 1.5 and 2.5 km resolutions and tested the performance in northern California during the 2008 wildfires. The localized product's algorithm uses local biomass burning aerosol optical properties, local surface reflectance data, and a relaxed cloud filter. During the 2008 season, persistent heavy smoke was produced over northern California and the San Joaquin Valley for over two months. As California is both highly populated and covered with a relatively dense network of ground-based aerosol monitoring stations, this event provided an excellent opportunity to develop the AOD product and test its ability to predict aerosol concentrations on the ground to assess population exposure. We will present our methodology and discuss its potential for air quality and public health applications.

  17. Isomeric product detection in the heterogeneous reaction of hydroxyl radicals with aerosol composed of branched and linear unsaturated organic molecules.

    PubMed

    Nah, Theodora; Zhang, Haofei; Worton, David R; Ruehl, Christopher R; Kirk, Benjamin B; Goldstein, Allen H; Leone, Stephen R; Wilson, Kevin R

    2014-12-11

    The influence of molecular structure (branched vs linear) on product formation in the heterogeneous oxidation of unsaturated organic aerosol is investigated. Particle phase product isomers formed from the reaction of squalene (C30H50, a branched alkene with six C═C double bonds) and linolenic acid (C18H30O2, a linear carboxylic acid with three C═C double bonds) with OH radicals are identified and quantified using two-dimensional gas chromatography-mass spectrometry. The reactions are measured at low and high [O2] (∼1% vs 10% [O2]) to understand the roles of hydroxyalkyl and hydroxyperoxy radical intermediates in product formation. A key reaction step is OH addition to a C═C double bond to form a hydroxyalkyl radical. In addition, allylic alkyl radicals, formed from H atom abstraction reactions by hydroxyalkyl or OH radicals play important roles in the chemistry of product formation. Functionalization products dominate the squalene reaction at ∼1% [O2], with the total abundance of observed functionalization products being approximately equal to the fragmentation products at 10% [O2]. The large abundance of squalene fragmentation products at 10% [O2] is attributed to the formation and dissociation of tertiary hydroxyalkoxy radical intermediates. For linolenic acid aerosol, the formation of functionalization products dominates the reaction at both ∼1% and 10% [O2], suggesting that the formation and dissociation of secondary hydroxyalkoxy radicals are minor reaction channels for linear molecules. The distribution of linolenic acid functionalization products depends upon [O2], indicating that O2 controls the reaction pathways of the secondary hydroxyalkyl radical. For both reactions, alcohols are formed in favor of carbonyl functional groups, suggesting that there are some key differences between heterogeneous reactions involving allylic radical intermediates and those reactions of OH radicals with simple saturated hydrocarbons.

  18. A Critical Examination of Spatial Biases Between MODIS and MISR Aerosol Products - Application for Potential AERONET Deployment

    NASA Technical Reports Server (NTRS)

    Shi, Y.; Zhang, J.; Reid, J. S.; Hyer, E. J.; Eck, T. F.; Holben, B. N.; Kahn, R. A.

    2011-01-01

    AErosol RObotic NETwork (AERONET) data are the primary benchmark for evaluating satellite-retrieved aerosol properties. However, despite its extensive coverage, the representativeness of the AERONET data is rarely discussed. Indeed, many studies have shown that satellite retrieval biases have a significant degree of spatial correlation that may be problematic for higher-level processes or inverse-emissions-modeling studies. To consider these issues and evaluate relative performance in regions of few surface observations, cross-comparisons between the Aerosol Optical Depth (AOD) products of operational MODIS Collection 5.1 Dark Target (DT) and operational MODIS Collection 5.1 Deep Blue (DB) with MISR version 22 were conducted. Through such comparisons, we can observe coherent spatial features of the AOD bias while side-stepping the full analysis required for determining when or where either retrieval is more correct. We identify regions where MODIS to MISR AOD ratios were found to be above 1.4 and below 0.7. Regions where lower boundary condition uncertainty is likely to be a dominant factor include portions of Western North America, the Andes mountains, Saharan Africa, the Arabian Peninsula, and Central Asia. Similarly, microphysical biases may be an issue in South America, and specific parts of Southern Africa, India Asia, East Asia, and Indonesia. These results help identify high-priority locations for possible future deployments of both in situ and ground based remote sensing measurements. The Supplement includes a km1 file.

  19. Validation of MODIS aerosol product with in-situ AERONET data (a study case in Hermosillo, Sonora, Mexico)

    NASA Astrophysics Data System (ADS)

    Valdes, M.; Leyva-Contreras, A.; Bonifaz, R.; Llamas, R.

    2009-12-01

    The aerosol optical thickness (AOT) is known as blocking particles which avoid the transmission of solar radiation coming from the Sun, and is defined as the integral of the coefficient of extinction over a vertical column of the Atmosphere. This coefficient of extinction is also defined as the limited fraction of the irradiance over the trajectory at a specific wavelength. The MODIS (Moderate Resolution Imaging Spectroradiometer) sensor provides aerosol data products all over the planet. However this data requires constant evaluation and validation using in-situ data such as the provided by the network of photometers managed by AERONET (Aerosol Robotic Network). In this work, the procedure of validation of the MODIS AOT data using AERONET data in the wavelengths of 660 and 675 nm is presented. It is expected that using validate remote sensing data which provides spatial and temporal information about the AOT will help to a better understanding of the behavior of the complex atmospheric conditions which characterize the NW of Mexico and SW of the US such as the Mexican monsoon.

  20. Aerosol typing - key information from aerosol studies

    NASA Astrophysics Data System (ADS)

    Mona, Lucia; Kahn, Ralph; Papagiannopoulos, Nikolaos; Holzer-Popp, Thomas; Pappalardo, Gelsomina

    2016-04-01

    Aerosol typing is a key source of aerosol information from ground-based and satellite-borne instruments. Depending on the specific measurement technique, aerosol typing can be used as input for retrievals or represents an output for other applications. Typically aerosol retrievals require some a priori or external aerosol type information. The accuracy of the derived aerosol products strongly depends on the reliability of these assumptions. Different sensors can make use of different aerosol type inputs. A critical review and harmonization of these procedures could significantly reduce related uncertainties. On the other hand, satellite measurements in recent years are providing valuable information about the global distribution of aerosol types, showing for example the main source regions and typical transport paths. Climatological studies of aerosol load at global and regional scales often rely on inferred aerosol type. There is still a high degree of inhomogeneity among satellite aerosol typing schemes, which makes the use different sensor datasets in a consistent way difficult. Knowledge of the 4d aerosol type distribution at these scales is essential for understanding the impact of different aerosol sources on climate, precipitation and air quality. All this information is needed for planning upcoming aerosol emissions policies. The exchange of expertise and the communication among satellite and ground-based measurement communities is fundamental for improving long-term dataset consistency, and for reducing aerosol type distribution uncertainties. Aerosol typing has been recognized as one of its high-priority activities of the AEROSAT (International Satellite Aerosol Science Network, http://aero-sat.org/) initiative. In the AEROSAT framework, a first critical review of aerosol typing procedures has been carried out. The review underlines the high heterogeneity in many aspects: approach, nomenclature, assumed number of components and parameters used for the

  1. 7 CFR 52.1842 - Product description of Layer or (Cluster) raisins with seeds.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 AND THE EGG PRODUCTS INSPECTION ACT PROCESSED FRUITS AND VEGETABLES, PROCESSED PRODUCTS THEREOF, AND CERTAIN OTHER PROCESSED FOOD PRODUCTS 1 United States Standards for Grades of Processed Raisins 1 § 52.1842 Product description of Layer or (Cluster) raisins...

  2. 7 CFR 52.1842 - Product description of Layer or (Cluster) raisins with seeds.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946 AND THE EGG PRODUCTS INSPECTION ACT PROCESSED FRUITS AND VEGETABLES, PROCESSED PRODUCTS THEREOF, AND CERTAIN OTHER PROCESSED FOOD PRODUCTS 1 United States Standards for Grades of Processed Raisins 1 § 52.1842 Product description of Layer or (Cluster) raisins...

  3. Global Long-Term SeaWiFS Deep Blue Aerosol Products available at NASA GES DISC

    NASA Technical Reports Server (NTRS)

    Shen, Suhung; Sayer, A. M.; Bettenhausen, Corey; Wei, Jennifer C.; Ostrenga, Dana M.; Vollmer, Bruce E.; Hsu, Nai-Yung; Kempler, Steven J.

    2012-01-01

    Long-term climate data records about aerosols are needed in order to improve understanding of air quality, radiative forcing, and for many other applications. The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) provides a global well-calibrated 13- year (1997-2010) record of top-of-atmosphere radiance, suitable for use in retrieval of atmospheric aerosol optical depth (AOD). Recently, global aerosol products derived from SeaWiFS with Deep Blue algorithm (SWDB) have become available for the entire mission, as part of the NASA Making Earth Science data records for Use in Research for Earth Science (MEaSUREs) program. The latest Deep Blue algorithm retrieves aerosol properties not only over bright desert surfaces, but also vegetated surfaces, oceans, and inland water bodies. Comparisons with AERONET observations have shown that the data are suitable for quantitative scientific use [1],[2]. The resolution of Level 2 pixels is 13.5x13.5 km2 at the center of the swath. Level 3 daily and monthly data are composed by using best quality level 2 pixels at resolution of both 0.5ox0.5o and 1.0ox1.0o. Focusing on the southwest Asia region, this presentation shows seasonal variations of AOD, and the result of comparisons of 5-years (2003- 2007) of AOD from SWDB (Version 3) and MODIS Aqua (Version 5.1) for Dark Target (MYD-DT) and Deep Blue (MYD-DB) algorithms.

  4. APPLICATION OF POLLUTION PREVENTION TECHNIQUES TO REDUCE INDOOR AIR EMISSONS FROM AEROSOL CONSUMER PRODUCTS

    EPA Science Inventory

    The report gives results of a research project to develop tools and methodologies to measure aerosol chemical and particle dispersion through space. These tools can be used to devise pollution prevention strategies that could reduce occupant chemical exposures and guide manufactu...

  5. Influence of aerosol estimation on coastal water products retrieved from HICO images

    NASA Astrophysics Data System (ADS)

    Patterson, Karen W.; Lamela, Gia

    2011-06-01

    The Hyperspectral Imager for the Coastal Ocean (HICO) is a hyperspectral sensor which was launched to the International Space Station in September 2009. The Naval Research Laboratory (NRL) has been developing the Coastal Water Signatures Toolkit (CWST) to estimate water depth, bottom type and water column constituents such as chlorophyll, suspended sediments and chromophoric dissolved organic matter from hyperspectral imagery. The CWST uses a look-up table approach, comparing remote sensing reflectance spectra observed in an image to a database of modeled spectra for pre-determined water column constituents, depth and bottom type. In order to successfully use this approach, the remote sensing reflectances must be accurate which implies accurately correcting for the atmospheric contribution to the HICO top of the atmosphere radiances. One tool the NRL is using to atmospherically correct HICO imagery is Correction of Coastal Ocean Atmospheres (COCOA), which is based on Tafkaa 6S. One of the user input parameters to COCOA is aerosol optical depth or aerosol visibility, which can vary rapidly over short distances in coastal waters. Changes to the aerosol thickness results in changes to the magnitude of the remote sensing reflectances. As such, the CWST retrievals for water constituents, depth and bottom type can be expected to vary in like fashion. This work is an illustration of the variability in CWST retrievals due to inaccurate aerosol thickness estimation during atmospheric correction of HICO images.

  6. Aqueous aerosol SOA formation: impact on aerosol physical properties.

    PubMed

    Woo, Joseph L; Kim, Derek D; Schwier, Allison N; Li, Ruizhi; McNeill, V Faye

    2013-01-01

    Organic chemistry in aerosol water has recently been recognized as a potentially important source of secondary organic aerosol (SOA) material. This SOA material may be surface-active, therefore potentially affecting aerosol heterogeneous activity, ice nucleation, and CCN activity. Aqueous aerosol chemistry has also been shown to be a potential source of light-absorbing products ("brown carbon"). We present results on the formation of secondary organic aerosol material in aerosol water and the associated changes in aerosol physical properties from GAMMA (Gas-Aerosol Model for Mechanism Analysis), a photochemical box model with coupled gas and detailed aqueous aerosol chemistry. The detailed aerosol composition output from GAMMA was coupled with two recently developed modules for predicting a) aerosol surface tension and b) the UV-Vis absorption spectrum of the aerosol, based on our previous laboratory observations. The simulation results suggest that the formation of oligomers and organic acids in bulk aerosol water is unlikely to perturb aerosol surface tension significantly. Isoprene-derived organosulfates are formed in high concentrations in acidic aerosols under low-NO(x) conditions, but more experimental data are needed before the potential impact of these species on aerosol surface tension may be evaluated. Adsorption of surfactants from the gas phase may further suppress aerosol surface tension. Light absorption by aqueous aerosol SOA material is driven by dark glyoxal chemistry and is highest under high-NO(x) conditions, at high relative humidity, in the early morning hours. The wavelength dependence of the predicted absorption spectra is comparable to field observations and the predicted mass absorption efficiencies suggest that aqueous aerosol chemistry can be a significant source of aerosol brown carbon under urban conditions. PMID:24601011

  7. Black carbon in aerosol during BIBLE B

    NASA Astrophysics Data System (ADS)

    Liley, J. Ben; Baumgardner, D.; Kondo, Y.; Kita, K.; Blake, D. R.; Koike, M.; Machida, T.; Takegawa, N.; Kawakami, S.; Shirai, T.; Ogawa, T.

    2002-02-01

    The Biomass Burning and Lightning Experiment (BIBLE) A and B campaigns over the tropical western Pacific during springtime deployed a Gulfstream-II aircraft with systems to measure ozone and numerous precursor species. Aerosol measuring systems included a MASP optical particle counter, a condensation nucleus (CN) counter, and an absorption spectrometer for black carbon. Aerosol volume was very low in the middle and upper troposphere during both campaigns, and during BIBLE A, there was little aerosol enhancement in the boundary layer away from urban areas. In BIBLE B, there was marked aerosol enhancement in the lowest 3 km of the atmosphere. Mixing ratios of CN in cloud-free conditions in the upper troposphere were in general higher than in the boundary layer, indicating new particle formation from gaseous precursors. High concentrations of black carbon were observed during BIBLE B, with mass loadings up to 40 μg m-3 representing as much as one quarter of total aerosol mass. Strong correlations with hydrocarbon enhancement allow the determination of a black carbon emission ratio for the fires at that time. Expressed as elemental carbon, it is about 0.5% of carbon dioxide and 6% of carbon monoxide emissions from the same fires, comparable to methane production, and greater than that of other hydrocarbons.

  8. Black carbon in aerosol during BIBLE B

    NASA Astrophysics Data System (ADS)

    Liley, J. Ben; Baumgardner, D.; Kondo, Y.; Kita, K.; Blake, D. R.; Koike, M.; Machida, T.; Takegawa, N.; Kawakami, S.; Shirai, T.; Ogawa, T.

    2003-02-01

    The Biomass Burning and Lightning Experiment (BIBLE) A and B campaigns over the tropical western Pacific during springtime deployed a Gulfstream-II aircraft with systems to measure ozone and numerous precursor species. Aerosol measuring systems included a MASP optical particle counter, a condensation nucleus (CN) counter, and an absorption spectrometer for black carbon. Aerosol volume was very low in the middle and upper troposphere during both campaigns, and during BIBLE A, there was little aerosol enhancement in the boundary layer away from urban areas. In BIBLE B, there was marked aerosol enhancement in the lowest 3 km of the atmosphere. Mixing ratios of CN in cloud-free conditions in the upper troposphere were in general higher than in the boundary layer, indicating new particle formation from gaseous precursors. High concentrations of black carbon were observed during BIBLE B, with mass loadings up to 40 μg m-3 representing as much as one quarter of total aerosol mass. Strong correlations with hydrocarbon enhancement allow the determination of a black carbon emission ratio for the fires at that time. Expressed as elemental carbon, it is about 0.5% of carbon dioxide and 6% of carbon monoxide emissions from the same fires, comparable to methane production, and greater than that of other hydrocarbons.

  9. Products and mechanism of secondary organic aerosol formation from reactions of linear alkenes with NO3 radicals.

    PubMed

    Gong, Huiming; Matsunaga, Aiko; Ziemann, Paul J

    2005-05-19

    Secondary organic aerosol (SOA) formation from reactions of linear alkenes with NO(3) radicals was investigated in an environmental chamber using a thermal desorption particle beam mass spectrometer for particle analysis. A general chemical mechanism was developed to explain the formation of the observed SOA products. The major first-generation SOA products were hydroxynitrates, carbonylnitrates, nitrooxy peroxynitrates, dihydroxynitrates, and dihydroxy peroxynitrates. The major second-generation SOA products were hydroxy and oxo dinitrooxytetrahydrofurans, which have not been observed previously. The latter compounds were formed by a series of reactions in which delta-hydroxycarbonyls isomerize to cyclic hemiacetals, which then dehydrate to form substituted dihydrofurans (unsaturated compounds) that rapidly react with NO(3) radicals to form very low volatility products. For the approximately 1 ppmv alkene concentrations used here, aerosol formed only for alkenes C(7) or larger. SOA formed from C(7)-C(9) alkenes consisted only of second-generation products, whereas for larger alkenes first-generation products were also present and contributions increased with increasing carbon number apparently due to the formation of lower volatility products. The estimated mass fractions of first- and second-generation products were approximately 50:50, 30:70, 10:90, and 0:100, for 1-tetradecene, 1-dodecene, 1-decene, and 1-octene SOA, respectively. This study shows that delta-hydroxycarbonyls play a key role in the formation of SOA in alkene-NO(3) reactions and are likely to be important in other systems because delta-hydroxycarbonyls can also be formed from reactions of OH radicals and O(3) with hydrocarbons.

  10. Using MAIAC Aerosol Products to Estimate PM10 Concentrations in the Southeastern U.S

    NASA Astrophysics Data System (ADS)

    Jinnagara Puttaswamy, S.; Hu, X.; Lyapustin, A.; Wang, Y.; Liu, Y.

    2012-12-01

    Acute and chronic exposure to particulate matter has been linked to various adverse health effects. High PM levels including inhalable particles (PM10) and fine particles (PM2.5) are commonly found in large urban centers in the developing world. Unlike PM2.5 whose routine ground monitoring is very sparse, PM10 is regularly measured in many large cities in developing countries. In this analysis, we evaluate the potential for satellite aerosol remote sensing product to estimate PM10 levels. We chose AOD values in 2003 retrieved by the Multiangle Implementation of Atmospheric Correction (MAIAC) algorithm based on MODIS measurements, which has a high spatial resolution of 1 km. Our study area is a 600 km x 600 km region centered in Atlanta, GA. Linear mixed effect (LME) models were developed with MAIAC AOD as the primary predictor variable, meteorology, PM10 emission locations and land use variables as secondary predictor variables. Daily PM10 concentrations measured at ~70 EPA air quality monitoring stations were used as the dependent variable. Model day of year was used as the grouping factor for the random effect of MAIAC AOD. We aggregated AOD and other covariates on 1 km, 3km, 5km and 10km resolution grids and similar LME models were developed for each spatial resolution to compare their abilities to capture the spatial patterns of PM10 mass concentrations at various scales. Our models show that MAIAC AOD, temperature, wind speed and PM 10 emissions source locations are statistically significant predictors of PM 10 at all the spatial scales. Model fitting R2 ranges from 0.35 in winter to 0.56 in the summer. Model performances show a slight decline as the grid resolution decreases. Although the performances of PM10 exposure models are not as good as those of PM2.5 models reported in the literature, these models can still provide spatially resolved PM10 levels at urban scale, which would enable preliminary PM10-related public health research in developing countries.

  11. Single and multi-layered core-shell structures based on ZnO nanorods obtained by aerosol assisted chemical vapor deposition

    SciTech Connect

    Sáenz-Trevizo, A.; Amézaga-Madrid, P.; Pizá-Ruiz, P.; Antúnez-Flores, W.; Ornelas-Gutiérrez, C.; Miki-Yoshida, M.

    2015-07-15

    Core–shell nanorod structures were prepared by a sequential synthesis using an aerosol assisted chemical vapor deposition technique. Several samples consisting of ZnO nanorods were initially grown over TiO{sub 2} film-coated borosilicate glass substrates, following the synthesis conditions reported elsewhere. Later on, a uniform layer consisting of individual Al, Ni, Ti or Fe oxides was grown onto ZnO nanorod samples forming the so-called single MO{sub x}/ZnO nanorod core–shell structures, where MO{sub x} was the metal oxide shell. Additionally, a three-layer core–shell sample was developed by growing Fe, Ti and Fe oxides alternately, onto the ZnO nanorods. The microstructure of the core–shell materials was characterized by grazing incidence X-ray diffraction, scanning and transmission electron microscopy. Energy dispersive X-ray spectroscopy was employed to corroborate the formation of different metal oxides. X-ray diffraction outcomes for single core–shell structures showed solely the presence of ZnO as wurtzite and TiO{sub 2} as anatase. For the multi-layered shell sample, the existence of Fe{sub 2}O{sub 3} as hematite was also detected. Morphological observations suggested the existence of an outer material grown onto the nanorods and further microstructural analysis by HR-STEM confirmed the development of core–shell structures in all cases. These studies also showed that the individual Al, Fe, Ni and Ti oxide layers are amorphous; an observation that matched with X-ray diffraction analysis where no apparent extra oxides were detected. For the multi-layered sample, the development of a shell consisting of three different oxide layers onto the nanorods was found. Overall results showed that no alteration in the primary ZnO core was produced during the growth of the shells, indicating that the deposition technique used herein was and it is suitable for the synthesis of homogeneous and complex nanomaterials high in quality and purity. In addition

  12. Small global effect on terrestrial net primary production due to increased fossil fuel aerosol emissions from East Asia since the turn of the century

    PubMed Central

    Rap, A.; Reddington, C. L.; Spracklen, D. V.; Gloor, M.; Buermann, W.

    2016-01-01

    Abstract The global terrestrial carbon sink has increased since the start of this century at a time of growing carbon emissions from fossil fuel burning. Here we test the hypothesis that increases in atmospheric aerosols from fossil fuel burning enhanced the diffuse light fraction and the efficiency of plant carbon uptake. Using a combination of models, we estimate that at global scale changes in light regimes from fossil fuel aerosol emissions had only a small negative effect on the increase in terrestrial net primary production over the period 1998–2010. Hereby, the substantial increases in fossil fuel aerosol emissions and plant carbon uptake over East Asia were effectively canceled by opposing trends across Europe and North America. This suggests that if the recent increase in the land carbon sink would be causally linked to fossil fuel emissions, it is unlikely via the effect of aerosols but due to other factors such as nitrogen deposition or nitrogen‐carbon interactions. PMID:27773953

  13. Aldol Condensation Products and Polyacetals in Organic Films Formed from Reactions of Propanal in Sulfuric Acid at Upper Troposphere/Lower Stratosphere (UT/LS) Aerosol Acidities

    NASA Astrophysics Data System (ADS)

    Bui, J. V. H.; Perez-Montano, S.; Li, E. S. W.; Nelson, T. E.; Ha, K. T.; Leong, L.; Iraci, L. T.; Van Wyngarden, A. L.

    2015-12-01

    Aerosols in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40-80 wt. %) which is highly reflective towards UV and visible radiation. However, airborne measurements have shown that these particles may also contain a significant amount of organic material. Experiments combining organics (propanal, glyoxal and/or methylglyoxal) with sulfuric acid at concentrations typical of UT/LS aerosols produced highly colored surface films (and solutions) that have the potential to impact chemical, optical and/or cloud-forming properties of aerosols. In order to assess the potential for such films to impact aerosol chemistry or climate properties, experiments were performed to identify the chemical processes responsible for film formation. Surface films were analyzed via Attenuated Total Reflectance-FTIR and Nuclear Magnetic Resonance spectroscopies and are shown to consist primarily of aldol condensation products and cyclic and linear polyacetals, the latter of which are likely responsible for separation from the aqueous phase.

  14. Aerosol Climate Time Series in ESA Aerosol_cci

    NASA Astrophysics Data System (ADS)

    Popp, Thomas; de Leeuw, Gerrit; Pinnock, Simon

    2016-04-01

    Within the ESA Climate Change Initiative (CCI) Aerosol_cci (2010 - 2017) conducts intensive work to improve algorithms for the retrieval of aerosol information from European sensors. Meanwhile, full mission time series of 2 GCOS-required aerosol parameters are completely validated and released: Aerosol Optical Depth (AOD) from dual view ATSR-2 / AATSR radiometers (3 algorithms, 1995 - 2012), and stratospheric extinction profiles from star occultation GOMOS spectrometer (2002 - 2012). Additionally, a 35-year multi-sensor time series of the qualitative Absorbing Aerosol Index (AAI) together with sensitivity information and an AAI model simulator is available. Complementary aerosol properties requested by GCOS are in a "round robin" phase, where various algorithms are inter-compared: fine mode AOD, mineral dust AOD (from the thermal IASI spectrometer, but also from ATSR instruments and the POLDER sensor), absorption information and aerosol layer height. As a quasi-reference for validation in few selected regions with sparse ground-based observations the multi-pixel GRASP algorithm for the POLDER instrument is used. Validation of first dataset versions (vs. AERONET, MAN) and inter-comparison to other satellite datasets (MODIS, MISR, SeaWIFS) proved the high quality of the available datasets comparable to other satellite retrievals and revealed needs for algorithm improvement (for example for higher AOD values) which were taken into account for a reprocessing. The datasets contain pixel level uncertainty estimates which were also validated and improved in the reprocessing. For the three ATSR algorithms the use of an ensemble method was tested. The paper will summarize and discuss the status of dataset reprocessing and validation. The focus will be on the ATSR, GOMOS and IASI datasets. Pixel level uncertainties validation will be summarized and discussed including unknown components and their potential usefulness and limitations. Opportunities for time series extension

  15. Reaction of oleic acid particles with NO3 radicals: Products, mechanism, and implications for radical-initiated organic aerosol oxidation.

    PubMed

    Docherty, Kenneth S; Ziemann, Paul J

    2006-03-16

    The heterogeneous reaction of liquid oleic acid aerosol particles with NO3 radicals in the presence of NO2, N2O5, and O2 was investigated in an environmental chamber using a combination of on-line and off-line mass spectrometric techniques. The results indicate that the major reaction products, which are all carboxylic acids, consist of hydroxy nitrates, carbonyl nitrates, dinitrates, hydroxydinitrates, and possibly more highly nitrated products. The key intermediate in the reaction is the nitrooxyalkylperoxy radical, which is formed by the addition of NO3 to the carbon-carbon double bond and subsequent addition of O2. The nitrooxyalkylperoxy radicals undergo self-reactions to form hydroxy nitrates and carbonyl nitrates, and may also react with NO2 to form nitrooxy peroxynitrates. The latter compounds are unstable and decompose to carbonyl nitrates and dinitrates. It is noteworthy that in this reaction nitrooxyalkoxy radicals appear not to be formed, as indicated by the absence of the expected products of decomposition or isomerization of these species. This is different from gas-phase alkene-NO3 reactions, in which a large fraction of the products are formed through these pathways. The results may indicate that, for liquid organic aerosol particles in low NOx environments, the major products of the radical-initiated oxidation (including by OH radicals) of unsaturated and saturated organic compounds will be substituted forms of the parent compound rather than smaller decomposition products. These compounds will remain in the particle and can potentially enhance particle hygroscopicity and the ability of particles to act as cloud condensation nuclei. PMID:16526637

  16. Production Mechanisms, Number Concentration, Size Distribution. Chemical Composition, and Optical Properties of Sea Spray Aerosols

    NASA Technical Reports Server (NTRS)

    Meskhidze, Nicholas; Petters, Markus; Tsigaridis, Kostas; Bates. Tim; O'Dowd, Colin; Reid, Jeff; Lewis, Ernie R.; Gantt, Brett; Anguelova, Magdalena D.; Bhave, Prakash V.; Bird, James; Callaghan, Adrian H.; Ceburnis, Darius; Chang, Rachel; Clark, Antony; deLeeuw, Gerrit; Deane, Grant; DeMott, Paul J.; Elliot, Scott; Facchini, Maria Cristina; Fairall, Chris W.; Hawkins, Lelia; Hu, Yongxiang; Smirnov, Alexander

    2013-01-01

    Over forty scientists from six countries convened in Raleigh, NC on June 4-6 2012 to review the status and prospects of sea spray aerosol research. Participants were researchers from the oceanography and atmospheric science communities, including academia, private industry, and government agencies. The recommendations from the working groups are summarized in a science prioritization matrix that is meant to prioritize the research agenda and identify areas of investigation by the magnitude of their impact on proposed science questions. Str

  17. LOAC: A light aerosol counter/sizer for atmospheric balloons

    NASA Astrophysics Data System (ADS)

    Renard, Jean-Baptiste; Thaury, Claire; Mineau, Jean-Luc; Verdier, Nicolas; Dulac, François; Mallet, Marc; Berthet, Gwenael; Gaubicher, Bertrand; Coute, Benoit

    The estimation of the total amount of aerosols in the upper troposphere and in lower -middle stratosphere is necessary to constraint the model calculations of the species that are sensi-tive to heterogeneous chemical reactions, to improve calculations on the atmospheric radiative transfer, and to better establish the sources of aerosols that are vertically transported up to the middle stratosphere. It is now known that different natures of aerosols can be found in the troposphere and in the stratosphere. These aerosols are made of liquid particles, and/or solid particles like soot, sands, meteoritic debris... The identification of the main nature of aerosols is not easily feasible using conventional aerosol counters, which perform in situ scat-tering measurements from a light source at a single angle typically in the 70-110 degrees range. Also, such counters are not very sensitive to soot particles that absorb the light but can be the main population of aerosols in the lower and middle stratosphere. In this work we describe a new generation of aerosol counters under development in the framework of the project LOAC (Light Optical Aerosol Counter) supported by the French ANR/Ecotech programme. LOAC will be a light particle counter/sizer, less than metricconverterProductID1 kg1 kg, designed to be mounted on the various kinds of tropospheric and stratospheric balloons. The measurements will be conducted at 2 scattering angles: the first one, at 10 degrees, is used to determine the aerosols concentration of several size classes within diameter range 0.3 and 20 micrometeres. At such low scattering angle close to forward scattering, the signal is much more intense and the measurements are not strongly sensitive to the nature of the aerosols. The second angle is at 60 degrees, where the light scattered is strongly dependent on the particle refractive index and thus on the nature of the aerosols. The ratio of the measurements at the 2 angles is used to determine the main

  18. Dusty Plasma Technology of DCM with Nanostructure Surface Layer Production

    SciTech Connect

    Gavrikov, A. V.; Ivanov, A. S.; Petrov, O. F.; Shulga, Yu. M.; Starostin, A. N.; Fortov, V. E.

    2008-09-07

    The technique of disperse composite material (DCM) production was developed. The technique based on using special dusty plasma trap in RF plasma, in which fine particles levitate and are exposed by the atomic beam. The two types of covering were obtained: ''cauliflower'' or smooth, depending on process condition.

  19. Synthesis and Analysis of Putative Terpene Oxidation Products and the Secondary Organic Aerosol Particles that Form from Them

    NASA Astrophysics Data System (ADS)

    Ebben, C. J.; Strick, B. F.; Upshur, M.; Shrestha, M.; Velarde, L.; Lu, Z.; Wang, H.; Xiao, D.; Batista, V. S.; Martin, S. T.; Thomson, R. J.; Geiger, F. M.

    2013-12-01

    The terpenes isoprene and α-pinene are abundant volatile organic compounds (VOCs) that are emitted by trees and oxidized in the atmosphere. However, the chemical processes involved in the formation of secondary organic aerosol (SOA) particles from VOCs are not well understood. In this work, we use a combined synthetic, analytical, and theoretical approach to gain a molecular level understanding of the chemistry involved in the formation of SOA particles from VOC precursors. To this end, we have synthesized putative products of isoprene and α-pinene oxidation and the oligomers that form from them. Specifically, we have focused on the epoxide and 2-methyltetraols that form from isoprene oxidation by hydroxyl radicals, as well as products of α-pinene ozonolysis. In our analysis, we utilize a spectroscopic technique called sum frequency generation (SFG). SFG is a coherent, surface-specific, vibrational spectroscopy that uses infrared and visible laser light fields, overlapped spatially and temporally at a surface, to probe vibrational transitions within molecules. Our use of this technique allows us to assess the chemical identity of aerosol-forming components at their surfaces, where interactions with the gas phase occur. The spectral responses from these compounds are compared to those of synthetic isoprene- and α-pinene-derived aerosol particles, as well as natural aerosol particles collected in tropical and boreal forests to begin to predict the constituents that may be present at the surfaces of these particles. In addition, isotope editing is utilized to gain a better understanding of α-pinene. The rigidity of this molecule makes it difficult to understand spectroscopically. The combination of synthesis with deuterium labeling, theory, and broadband and high-resolution SFG spectroscopy in the C-H and C-D stretching regions allow us to determine the orientation of this important molecule on a surface, which could have implications for its reactivity in the

  20. Influence of the air Layer Between the Conductor and the Layer Ofinsulating Material in Cable Products

    NASA Astrophysics Data System (ADS)

    Ivanova, Evgenia V.; Yashutina, Olga S.; Shidlovskiy, Stanisla V.

    2016-02-01

    There are developed mathematical model of physical and chemical processes of polymerization adhesive coating stranded cable. There are shown difference in the temperature distribution along the radius of the finished product in the presence of an air gap between the conductor and the rubber sheath. Also, due to the need to change process parameters with possible loose contacts inside the cable. Such as the temperature of the heating surface, feeding speed and dwell time in the oven.

  1. Laboratory studies of oxidation of primary emissions: Oxidation of organic molecular markers and secondary organic aerosol production

    NASA Astrophysics Data System (ADS)

    Weitkamp, Emily A.

    vehicle markers. Aerosol composition is a key influence on reaction rate constants, perhaps more significant than external influences. Alkenoic acid concentrations in the meat grease particles appear to influence cholesterol oxidation rates. Also, the reaction rate constants for new motor oil were faster than those of the more viscous used motor oil. The measured reaction rate constants were used to oxidize source profiles that were subsequently run in the Chemical Mass Balance (CMB) model. Oxidizing the molecular markers in the meat-cooking profile led to unrealistically high meat-cooking aerosol contributions to the total organic carbon (OC), often more than 100%. This suggests that there is either unaccounted for sources of meat-cooking molecular markers in the ambient samples, or there is some property of atmospheric aerosols that significantly inhibits reaction that was not captured in this study. Oxidation of motor vehicle profiles led to both higher estimates of total vehicle OC and a quadrupling of gasoline OC, while the diesel contribution changed very little. The increase in gasoline OC changes gasoline vehicle emissions from a relatively minor source to a major one. Thus, oxidation of molecular markers can have a significant impact on receptor model predictions. The second objective was to investigate SOA formation from the photo-oxidation of whole diesel exhaust. Diluted exhaust from a diesel engine was photo-oxidized in a smog chamber to investigate SOA production. Photochemical oxidation rapidly produced significant SOA, almost doubling the organic aerosol contribution of primary emissions after several hours of processing. Less than 10% of the SOA mass could be explained using a SOA model and the measured oxidation of known precursors, such as light aromatics. However, the ultimate yield of SOA is uncertain because it is sensitive to treatment of particle and vapor losses to the chamber walls. Aerosol Mass Spectrometer (AMS) mass spectra reveal that the

  2. NASA GES DISC Level 2 Aerosol Analysis and Visualization Services

    NASA Technical Reports Server (NTRS)

    Wei, Jennifer; Petrenko, Maksym; Ichoku, Charles; Yang, Wenli; Johnson, James; Zhao, Peisheng; Kempler, Steve

    2015-01-01

    Overview of NASA GES DISC Level 2 aerosol analysis and visualization services: DQViz (Data Quality Visualization)MAPSS (Multi-sensor Aerosol Products Sampling System), and MAPSS_Explorer (Multi-sensor Aerosol Products Sampling System Explorer).

  3. Relationships linking primary production, sea ice melting, and biogenic aerosol in the Arctic

    NASA Astrophysics Data System (ADS)

    Becagli, S.; Lazzara, L.; Marchese, C.; Dayan, U.; Ascanius, S. E.; Cacciani, M.; Caiazzo, L.; Di Biagio, C.; Di Iorio, T.; di Sarra, A.; Eriksen, P.; Fani, F.; Giardi, F.; Meloni, D.; Muscari, G.; Pace, G.; Severi, M.; Traversi, R.; Udisti, R.

    2016-07-01

    This study examines the relationships linking methanesulfonic acid (MSA, arising from the atmospheric oxidation of the biogenic dimethylsulfide, DMS) in atmospheric aerosol, satellite-derived chlorophyll a (Chl-a), and oceanic primary production (PP), also as a function of sea ice melting (SIM) and extension of the ice free area in the marginal ice zone (IF-MIZ) in the Arctic. MSA was determined in PM10 samples collected over the period 2010-2012 at two Arctic sites, Ny Ålesund (78.9°N, 11.9°E), Svalbard islands, and Thule Air Base (76.5°N, 68.8°W), Greenland. PP is calculated by means of a bio-optical, physiologically based, semi-analytical model in the potential source areas located in the surrounding oceanic regions (Barents and Greenland Seas for Ny Ålesund, and Baffin Bay for Thule). Chl-a peaks in May in the Barents sea and in the Baffin Bay, and has maxima in June in the Greenland sea; PP follows the same seasonal pattern of Chl-a, although the differences in absolute values of PP in the three seas during the blooms are less marked than for Chl-a. MSA shows a better correlation with PP than with Chl-a, besides, the source intensity (expressed by PP) is able to explain more than 30% of the MSA variability at the two sites; the other factors explaining the MSA variability are taxonomic differences in the phytoplanktonic assemblages, and transport processes from the DMS source areas to the sampling sites. The taxonomic differences are also evident from the slopes of the correlation plots between MSA and PP: similar slopes (in the range 34.2-36.2 ng m-3of MSA/(gC m-2 d-1)) are found for the correlation between MSA at Ny Ålesund and PP in Barents Sea, and between MSA at Thule and PP in the Baffin Bay; conversely, the slope of the correlation between MSA at Ny Ålesund and PP in the Greenland Sea in summer is smaller (16.7 ng m-3of MSA/(gC m-2 d-1)). This is due to the fact that DMS emission from the Barents Sea and Baffin Bay is mainly related to the MIZ

  4. The validation and comparison of the GOCI aerosol optical thickness products: a case study of Tianjin 8.12

    NASA Astrophysics Data System (ADS)

    Yao, Lingling; Zhang, Xiaoyu; Yu, Hui; Jiang, Binbin

    2016-01-01

    COMSGOCI (Geostationary Ocean Color Imager) is the first geostationary ocean color satellite in the world launched by South Korea in June 2010, which includes eight bands from the visible to the infrared band. GOCI aerosol optical thickness (AOT) at 555nm was retrieved by atmospheric radiative transfer model based on two-stream approximation algorithm. Due to GOCI without near infrared band and has a high solar elevation angle, solar zenith angle must be recalibrated to solve the earth system albedo, and the surface reflectance solved by quack atmospheric correction and recalculated backward scatter coefficient. Evaluation of GOCIAOT with AERONET measurements showed that the average error becomes 0.107 from the original 0.393, that means GOCI aerosol optical thickness can be more accurately with the advanced two-stream approximation. Taking the eastern China in 3 and 4 December 2013 for example, comparing the GOCIAOT at 555nm, MODISAOT retrievals at 550nm, NPPAOT at 550nm and AERONET data products indicated that: take the AERONET data as reference, the error of three kinds of satellite data can be ordered as following: MODISAOT< GOCIAOT< NPPAOT and the GOCI-MODIS shows a bias of 0.02917 with the GOCI-NPP. GOCIAOT is 0.05714 generally bigger than that of MODISAOT. NPP-GOCI deviation is 0.10253. The deficiency of MODIS is its low spatial resolution and the high concentration of AOT will be mistaken for a cloud area. However, GOCI can well reflect the concentration and distribution of aerosols. Therefore, GOGI can provide real-time dynamic monitoring on China Eastern atmospheric environment and the accurate time event information of haze for each process can be obtained. Finally, applied GOCI to the "8.12 Tianjin bombings" and to monitor the migration and dispersion of pollutant.

  5. Unattended Monitoring of HEU Production in Gaseous Centrifuge Enrichment Plants using Automated Aerosol Collection and Laser-based Enrichment Assay

    SciTech Connect

    Anheier, Norman C.; Bushaw, Bruce A.

    2010-08-11

    Nuclear power is enjoying rapid growth as government energy policies and public demand shift toward low carbon energy production. Pivotal to the global nuclear power renaissance is the development and deployment of robust safeguards instrumentation that allows the limited resources of the IAEA to keep pace with the expansion of the nuclear fuel cycle. Undeclared production of highly enriched uranium (HEU) remains a primary proliferation concern for modern gaseous centrifuge enrichment plants (GCEPs), due to their massive separative work unit (SWU) processing power and comparably short cascade equilibrium timescale. The Pacific Northwest National Laboratory is developing an unattended safeguards instrument, combining continuous aerosol particulate collection with uranium isotope assay, to provide timely detection of HEU production within a GCEP. This approach is based on laser vaporization of aerosol particulates, followed by laser spectroscopy to characterize the uranium enrichment level. Our prior investigation demonstrated single-shot detection sensitivity approaching the femtogram range and relative isotope ratio uncertainty better than 10% using gadolinium as a surrogate for uranium. In this paper we present measurement results on standard samples containing traces of depleted, natural, and low enriched uranium, as well as measurements on aerodynamic size uranium particles mixed in background materials (e.g., dust, minerals, soils). Improvements and optimizations in the detection electronics, signal timing, calibration, and laser alignment have lead to significant improvements in detection sensitivity and enrichment accuracy, contributing to an overall reduction in the false alarm probability. The sample substrate media was also found to play a significant role in facilitating laser-induced vaporization and the production of energetic plasma conditions, resulting in ablation optimization and further improvements in the isotope abundance sensitivity.

  6. Aerosol Monitoring during Carbon Nanofiber Production: Mobile Direct-Reading Sampling

    PubMed Central

    Evans, Douglas E.; Ku, Bon Ki; Birch, M. Eileen; Dunn, Kevin H.

    2010-01-01

    Detailed investigations were conducted at a facility that manufactures and processes carbon nanofibers (CNFs). Presented research summarizes the direct-reading monitoring aspects of the study. A mobile aerosol sampling platform, equipped with an aerosol instrument array, was used to characterize emissions at different locations within the facility. Particle number, respirable mass, active surface area, and photoelectric response were monitored with a condensation particle counter (CPC), a photometer, a diffusion charger, and a photoelectric aerosol sensor, respectively. CO and CO2 were additionally monitored. Combined simultaneous monitoring of these metrics can be utilized to determine source and relative contribution of airborne particles (CNFs and others) within a workplace. Elevated particle number concentrations, up to 1.15 × 106 cm−3, were found within the facility but were not due to CNFs. Ultrafine particle emissions, released during thermal treatment of CNFs, were primarily responsible. In contrast, transient increases in respirable particle mass concentration, with a maximum of 1.1 mg m−3, were due to CNF release through uncontrolled transfer and bagging. Of the applied metrics, our findings suggest that particle mass was probably the most useful and practical metric for monitoring CNF emissions in this facility. Through chemical means, CNFs may be selectively distinguished from other workplace contaminants (Birch et al., in preparation), and for direct-reading monitoring applications, the photometer was found to provide a reasonable estimate of respirable CNF mass concentration. Particle size distribution measurements were conducted with an electrical low-pressure impactor and a fast particle size spectrometer. Results suggest that the dominant CNF mode by particle number lies between 200 and 250 nm for both aerodynamic and mobility equivalent diameters. Significant emissions of CO were also evident in this facility. Exposure control recommendations

  7. Aerosol monitoring during carbon nanofiber production: mobile direct-reading sampling.

    PubMed

    Evans, Douglas E; Ku, Bon Ki; Birch, M Eileen; Dunn, Kevin H

    2010-07-01

    Detailed investigations were conducted at a facility that manufactures and processes carbon nanofibers (CNFs). Presented research summarizes the direct-reading monitoring aspects of the study. A mobile aerosol sampling platform, equipped with an aerosol instrument array, was used to characterize emissions at different locations within the facility. Particle number, respirable mass, active surface area, and photoelectric response were monitored with a condensation particle counter (CPC), a photometer, a diffusion charger, and a photoelectric aerosol sensor, respectively. CO and CO(2) were additionally monitored. Combined simultaneous monitoring of these metrics can be utilized to determine source and relative contribution of airborne particles (CNFs and others) within a workplace. Elevated particle number concentrations, up to 1.15 x 10(6) cm(-3), were found within the facility but were not due to CNFs. Ultrafine particle emissions, released during thermal treatment of CNFs, were primarily responsible. In contrast, transient increases in respirable particle mass concentration, with a maximum of 1.1 mg m(-3), were due to CNF release through uncontrolled transfer and bagging. Of the applied metrics, our findings suggest that particle mass was probably the most useful and practical metric for monitoring CNF emissions in this facility. Through chemical means, CNFs may be selectively distinguished from other workplace contaminants (Birch et al., in preparation), and for direct-reading monitoring applications, the photometer was found to provide a reasonable estimate of respirable CNF mass concentration. Particle size distribution measurements were conducted with an electrical low-pressure impactor and a fast particle size spectrometer. Results suggest that the dominant CNF mode by particle number lies between 200 and 250 nm for both aerodynamic and mobility equivalent diameters. Significant emissions of CO were also evident in this facility. Exposure control

  8. Response of North Pacific eastern subtropical mode water to greenhouse gas versus aerosol forcing

    NASA Astrophysics Data System (ADS)

    Li, Xiang; Luo, Yiyong

    2016-04-01

    Mode water is a distinct water mass characterized by a near vertical homogeneous layer or low potential vorticity, and is considered essential for understanding ocean climate variability. Based on the output of GFDL CM3, this study investigates the response of eastern subtropical mode water (ESTMW) in the North Pacific to two different single forcings: greenhouse gases (GHGs) and aerosol. Under GHG forcing, ESTMW is produced on lighter isopycnal surfaces and is decreased in volume. Under aerosol forcing, in sharp contrast, it is produced on denser isopycnal surfaces and is increased in volume. The main reason for the opposite response is because surface ocean-to-atmosphere latent heat flux change over the ESTMW formation region shoals the mixed layer and thus weakens the lateral induction under GHG forcing, but deepens the mixed layer and thus strengthens the lateral induction under aerosol forcing. In addition, local wind changes are also favorable to the opposite response of ESTMW production to GHG versus aerosol.

  9. A global survey of aerosol-liquid water cloud overlap based on four years of CALIPSO-CALIOP data

    NASA Astrophysics Data System (ADS)

    Devasthale, A.; Thomas, M. A.

    2010-09-01

    The presence of aerosols over highly reflective liquid water cloud tops poses a big challenge in simulating their radiative impacts. Particularly, absorbing aerosols, such as smoke, may have significant impact in such situations and even change the sign of net radiative forcing. Until now, it was not possible to obtain information on such overlap events realistically from the existing passive satellite sensors. However, the CALIOP instrument onboard NASA's CALIPSO satellite allows us to examine these events with an unprecedented accuracy. Using four years of collocated CALIPSO 5 km Aerosol and Cloud Layer Version 3 Products (June 2006-May 2010), we quantify, for the first time, the macrophysical characteristics of overlapping aerosol and water cloud layers globally. We investigate seasonal variability in these characteristics over six latitude bands to understand the hemispheric differences. We compute a) the percentage cases when such overlap is seen globally and seasonally when all aerosol types are included (AAO case) in the analysis, b) the joint histograms of aerosol layer base height and cloud layer top height, and c) the joint histograms of aerosol and cloud geometrical thicknesses in such overlap cases. We also investigate frequency of smoke aerosol-cloud overlap (SAO case). The results show a distinct seasonality in overlap frequency in both AAO and SAO cases. Globally, the frequency is highest during JJA months in AAO case, while for the SAO case, it is highest in SON months. The seasonal mean overlap frequency can regionally exceed 20% in AAO case and 10% in SAO case. There is a tendency that the vertical separation between aerosol and cloud layers increases from high to low latitude regions in the both hemispheres. In about 5-10% cases the vertical distance between aerosol and cloud layers is less than 100 m, while about in 45-60% cases it less than a kilometer in the annual means for different latitudinal bands. The frequency of occurrence of thicker

  10. Production of sulfate aerosols in the plume of a coal-fired power plant under normal and reduced precipitator operation

    SciTech Connect

    Meagher, J.F.; Bailey, E.M.; Stockburger, L. III

    1981-12-01

    A series of field experiments were conducted at TVA's Cumberland Steam Plant to examine the effect of primary aerosol on sulfate aerosol production. Plume measurements were made using an instrumented helicopter and flue gas analyses were performed on each of the two stacks. The plume particle loading was increased during four of the experiments through a reduction in the electrostatic precipitator (ESP) capacity. The average rate of oxidation of SO/sub 2/ to SO/sub 4//sup 2 -/ in the plume was found to be 0.014 +- 0.015 h/sup -1/. The average rate measured for daytime and normal ESP operation was 0.019 +- 0.015 h/sup -1/. The average nighttime rate was also 0.019 +- 0.021 h/sup -1/. The average rate measured during periods of reduced ESP operation was 0.007 +- 0.01 h/sup -1/. The relatively high night-time rates were measured just after sunset and may result from delayed reactions of free radical precursors which were produced during the day-light hours. The difference between extrapolated intercepts from aircraft measurements and flue gas sampling indicates that a region of rapid SO/sub 2/ oxidation must exist for the first few minutes after the flue gas is emitted from the stacks.

  11. Sea spray aerosol production measured in-situ and in a laboratory high-speed wind-wave tunnel

    NASA Astrophysics Data System (ADS)

    Savelyev, I.; Frick, G.; Anguelova, M. D.; Haus, B. K.

    2012-12-01

    This presentation overviews a series of experiments recently conducted in the open ocean onboard of Research Platform FLIP, as well as in the high speed Air-Sea Interaction Saltwater Tank (ASIST). In both experiments vertical profiles of size-dependent aerosol concentrations (0.01 - 47 μm range) were measured in close proximity to the air-sea interface using Scattering Aerosol Spectrometer and Differential Mobility Analyzer. Within ~7 days of useful open ocean measurements wind speed U10 varied in ~ 3 - 18 m/s range with significant wave height reaching up to ~ 5 m, whereas U10 wind speed equivalent in ASIST varied up to 40 m/s in addition to mechanically superimposed waves of arbitrary amplitudes. In both cases air-sea interface processes were observed with visible and infrared cameras and other standard instrumentation. This study seeks to evaluate the extent to which laboratory data can complement and aid in the analysis of open ocean measurements. The overall goal is to develop better understanding of underlying physical processes of spray production and its near-surface dynamics, which is needed for uncertainty reduction of existing sea spray source function formulations.

  12. Layers

    NASA Astrophysics Data System (ADS)

    Hong, K. J.; Jeong, T. S.; Youn, C. J.

    2014-09-01

    The temperature-dependent photoresponse characteristics of MnAl2S4 layers have been investigated, for the first time, by use of photocurrent (PC) spectroscopy. Three peaks were observed at all temperatures. The electronic origin of these peaks was associated with band-to-band transitions from the valence-band states Γ4( z), Γ5( x), and Γ5( y) to the conduction-band state Γ1( s). On the basis of the relationship between PC-peak energy and temperature, the optical band gap could be well expressed by the expression E g( T) = E g(0) - 2.80 × 10-4 T 2/(287 + T), where E g(0) was estimated to be 3.7920 eV, 3.7955 eV, and 3.8354 eV for the valence-band states Γ4( z), Γ5( x), and Γ5( y), respectively. Results from PC spectroscopy revealed the crystal-field and spin-orbit splitting were 3.5 meV and 39.9 meV. The gradual decrease of PC intensity with decreasing temperature can be explained on the basis of trapping centers associated with native defects in the MnAl2S4 layers. Plots of log J ph, the PC current density, against 1/ T, revealed a dominant trap level in the high-temperature region. By comparing PC and the Hall effect results, we confirmed that this trap level is a shallow donor 18.9 meV below the conduction band.

  13. Comparisons of Airborne HSRL and Modeled Aerosol Profiles

    NASA Astrophysics Data System (ADS)

    Ferrare, R. A.; Burton, S. P.; Hostetler, C. A.; Hair, J. W.; Ismail, S.; Rogers, R. R.; Notari, A.; Berkoff, T.; Butler, C. F.; Collins, J. E., Jr.; Fenn, M. A.; Scarino, A. J.; Clayton, M.; Mueller, D.; Chemyakin, E.; Fast, J. D.; Berg, L. K.; Randles, C. A.; Colarco, P. R.; daSilva, A.

    2014-12-01

    Aerosol profiles derived from a regional and a global model are compared with aerosol profiles acquired by NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidars (HSRLs) during recent field missions. We compare simulated aerosol profiles obtained from the WRF-Chem regional model with those measured by the airborne HSRL-2 instrument over the Atlantic Ocean east of Cape Cod in July 2012 during the Department of Energy Two-Column Aerosol Project (TCAP). While deployed on the LaRC King Air during TCAP, HSRL-2 acquired profiles of aerosol extinction at 355 and 532 nm, as well as aerosol backscatter and depolarization at 355, 532, and 1064 nm. Additional HSRL-2 data products include profiles of aerosol type, mixed layer depth, and aerosol microphysical parameters (e.g. effective radius, concentration). The HSRL-2 and WRF-Chem aerosol profiles are compared along the aircraft flight tracks. HSRL-2 profiles acquired during the NASA Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) mission over Houston during September 2013 are compared with the NASA Goddard Earth Observing System global model, version 5 (GEOS-5) profiles. In addition to comparing backscatter and extinction profiles, the fraction of aerosol extinction and optical thickness from various aerosol species from GEOS-5 are compared with aerosol extinction and optical thickness contributed by aerosol types derived from HSRL-2 data. We also compare aerosol profiles modeled by GEOS-5 with those measured by the airborne LaRC DIAL/HSRL instrument during August and September 2013 when it was deployed on the NASA DC-8 for the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) mission. DIAL/HSRL measured extinction (532 nm), backscatter (532 and 1064 nm), and depolarization profiles (532 and 1064 nm) in both nadir and zenith directions during long transects over the

  14. Retrieving the height of smoke and dust aerosols by synergistic use of VIIRS, OMPS, and CALIOP observations

    NASA Astrophysics Data System (ADS)

    Lee, Jaehwa; Hsu, N. Christina; Bettenhausen, Corey; Sayer, Andrew M.; Seftor, Colin J.; Jeong, Myeong-Jae

    2015-08-01

    This study extends the application of the previously developed Aerosol Single-scattering albedo and layer Height Estimation (ASHE) algorithm, which was originally applied to smoke aerosols only, to both smoke and dust aerosols by including nonspherical dust properties in the retrieval process. The main purpose of the algorithm is to derive aerosol height information over wide areas using aerosol products from multiple satellite sensors simultaneously: aerosol optical depth (AOD) and Ångström exponent from the Visible Infrared Imaging Radiometer Suite (VIIRS), UV aerosol index from the Ozone Mapping and Profiler Suite (OMPS), and total backscatter coefficient profile from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). The case studies suggest that the ASHE algorithm performs well for both smoke and dust aerosols, showing root-mean-square error of the retrieved aerosol height as compared to CALIOP observations from 0.58 to 1.31 km and mean bias from -0.70 to 1.13 km. In addition, the algorithm shows the ability to retrieve single-scattering albedo to within 0.03 of Aerosol Robotic Network inversion data for moderate to thick aerosol loadings (AOD of ~1.0). For typical single-layered aerosol cases, the estimated uncertainty in the retrieved height ranges from 1.20 to 1.80 km over land and from 1.15 to 1.58 km over ocean when favorable conditions are met. Larger errors are observed for multilayered aerosol events, due to the limited sensitivities of the passive sensors to such cases.

  15. Production and Study of Titan's Aerosols Analogues with A RF Low Pressure Plasma Discharge

    SciTech Connect

    Szopa, C.; Cernogora, G.; Correia, J.J.; Boufendi, L.; Jolly, A.

    2005-10-31

    The atmosphere of Titan, the biggest satellite of Saturn, contains aerosols produced by the organic chemistry induced by the photochemistry of N2 and CH4, the major gaseous atmospheric compounds. In spite of their importance for the properties of the Titan's atmosphere, and for organic chemistry, only few direct information are available about them because of the limitations of the observational techniques, and their processes of formation and growth are not understood. In order to bring answers to these questions, we developed a new type of laboratory simulation to produce analogues of Titan's aerosols (known as tholins) with a low pressure Radio Frequency plasma discharge. The main originality of this experiment (named PAMPRE) comes from its ability to produce particles in volume, as they are maintained in levitation by electrostatic forces compensating gravity, whereas the other experiments produce tholins on the reactors walls or a substrate. We initiated our investigations by a study of the properties of the produced particles as a function of the plasma operating conditions (i.e. amount of CH4 in N2, injected RF power, pressure, and gas flow). We here present the results of this study.

  16. Joint retrieval of aerosol and water-leaving radiance from multispectral, multiangular and polarimetric measurements over ocean

    NASA Astrophysics Data System (ADS)

    Xu, Feng; Dubovik, Oleg; Zhai, Peng-Wang; Diner, David J.; Kalashnikova, Olga V.; Seidel, Felix C.; Litvinov, Pavel; Bovchaliuk, Andrii; Garay, Michael J.; van Harten, Gerard; Davis, Anthony B.

    2016-07-01

    An optimization approach has been developed for simultaneous retrieval of aerosol properties and normalized water-leaving radiance (nLw) from multispectral, multiangular, and polarimetric observations over ocean. The main features of the method are (1) use of a simplified bio-optical model to estimate nLw, followed by an empirical refinement within a specified range to improve its accuracy; (2) improved algorithm convergence and stability by applying constraints on the spatial smoothness of aerosol loading and Chlorophyll a (Chl a) concentration across neighboring image patches and spectral constraints on aerosol optical properties and nLw across relevant bands; and (3) enhanced Jacobian calculation by modeling and storing the radiative transfer (RT) in aerosol/Rayleigh mixed layer, pure Rayleigh-scattering layers, and ocean medium separately, then coupling them to calculate the field at the sensor. This approach avoids unnecessary and time-consuming recalculations of RT in unperturbed layers in Jacobian evaluations. The Markov chain method is used to model RT in the aerosol/Rayleigh mixed layer and the doubling method is used for the uniform layers of the atmosphere-ocean system. Our optimization approach has been tested using radiance and polarization measurements acquired by the Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) over the AERONET USC_SeaPRISM ocean site (6 February 2013) and near the AERONET La Jolla site (14 January 2013), which, respectively, reported relatively high and low aerosol loadings. Validation of the results is achieved through comparisons to AERONET aerosol and ocean color products. For comparison, the USC_SeaPRISM retrieval is also performed by use of the Generalized Retrieval of Aerosol and Surface Properties algorithm (Dubovik et al., 2011). Uncertainties of aerosol and nLw retrievals due to random and systematic instrument errors are analyzed by truth-in/truth-out tests with three Chl a concentrations, five aerosol loadings

  17. Atomic layer epitaxy of Ruddlesden-Popper SrO(SrTiO{sub 3}){sub n} films by means of metalorganic aerosol deposition

    SciTech Connect

    Jungbauer, M.; Hühn, S.; Moshnyaga, V.; Egoavil, R.; Tan, H.; Verbeeck, J.; Van Tendeloo, G.

    2014-12-22

    We report an atomic layer epitaxial growth of Ruddlesden-Popper (RP) thin films of SrO(SrTiO{sub 3}){sub n} (n = ∞, 2, 3, 4) by means of metalorganic aerosol deposition (MAD). The films are grown on SrTiO{sub 3}(001) substrates by means of a sequential deposition of Sr-O/Ti-O{sub 2} atomic monolayers, monitored in-situ by optical ellipsometry. X-ray diffraction and transmission electron microscopy (TEM) reveal the RP structure with n = 2–4 in accordance with the growth recipe. RP defects, observed by TEM in a good correlation with the in-situ ellipsometry, mainly result from the excess of SrO. Being maximal at the film/substrate interface, the SrO excess rapidly decreases and saturates after 5–6 repetitions of the SrO(SrTiO{sub 3}){sub 4} block at the level of 2.4%. This identifies the SrTiO{sub 3} substrate surface as a source of RP defects under oxidizing conditions within MAD. Advantages and limitations of MAD as a solution-based and vacuum-free chemical deposition route were discussed in comparison with molecular beam epitaxy.

  18. Organosulfates and oxidation products from biogenic hydrocarbons in fine aerosols from a forest in North West Europe during spring

    NASA Astrophysics Data System (ADS)

    Kristensen, Kasper; Glasius, Marianne

    2011-09-01

    Organosulfates of monoterpenes and isoprene, as well as their oxidation products have been identified in biogenic secondary organic aerosols (BSOA) from both laboratory and field studies. Organosulfates provide an interesting coupling between air pollution and formation of low-volatility BSOA. HPLC quadrupole time-of-flight mass spectrometry was used to study polar acidic monoterpene and isoprene oxidation products including pinic acid, pinonic and terpenylic acid along with organosulfates and nitrooxy organosulfates in aerosols from ambient air. The method was first validated by analysis of spiked quartz filters, which showed acceptable recoveries >74% for pinic acid, pinonic acid, camphor sulphonic acid and adipic acid. Acetonitrile was identified as a better solvent than methanol for extraction and analysis of pinonic acid and adipic acid, due to improved analytical sensitivity and prevention of methyl ester formation during sample extraction. PM 1 (i.e, aerosols with an aerodynamic diameter ≤1 μm) were collected during spring 2008 in a forest in Denmark with mixed deciduous and coniferous trees. Average concentrations of the most abundant compounds were: pinic acid: 1.5 ng m -3, pinonic acid: 3.0 ng m -3, terpenylic acid: 0.8 ng m -3 and 3-methyl-1,2,3-butanetricarboxylic acid: 3.0 ng m -3. Organosulfates and nitrooxy organosulfates were identified in a majority of the daily samples and the highest levels were observed during a warm period in late spring. As a first approach, due to the lack of authentic standards, organosulfates and nitrooxy organosulfates were tentatively quantified based on the analytical response of camphor sulphonic acid. Generally the concentrations of organosulfates and nitrooxy organosulfates were lower than first generation oxidation products. The maximum concentration of a total of 10 organosulfates and nitrooxy organosulfates were found to be about three times lower than pinonic acid with a maximum concentration of 8 ng m -3. A

  19. Anthropogenic Aerosol Radiative Forcing in Asia Derived From Regional Models With Atmospheric and Aerosol Data Assimilation

    SciTech Connect

    Chung, Chul Eddy; Ramanathan, V.; Carmichael, Gregory; Kulkarni, S.; Tang, Youhua; Adhikary, Bhupesh; Leung, Lai-Yung R.; Qian, Yun

    2010-07-05

    A high-resolution estimate of monthly 3D aerosol solar heating rates and surface solar fluxes in Asia from 2001 to 2004 is described here. This product stems from an Asian aerosol assimilation project, in which a) the PNNL regional model bounded by the NCEP reanalyses was used to provide meteorology, b) MODIS and AERONET data were integrated for aerosol observations, c) the Iowa aerosol/chemistry model STEM-2K1 used the PNNL meteorology and assimilated aerosol observations, and d) 3D (X-Y-Z) aerosol simulations from the STEM-2K1 were used in the Scripps Monte-Carlo Aerosol Cloud Radiation (MACR) model to produce total and anthropogenic aerosol direct solar forcing for average cloudy skies. The MACR model and STEM both used the PNNL model resolution of 0.45º×0.4º in the horizontal and of 23 layers in the troposphere. The 2001–2004 averaged anthropogenic all-sky aerosol forcing is -1.3 Wm-2 (TOA), +7.3 Wm-2 (atmosphere) and -8.6 Wm-2 (surface) averaged in Asia (60-138°E & Eq. -45°N). In the absence of AERONET SSA assimilation, absorbing aerosol concentration (especially BC aerosol) is much smaller, giving -2.3 Wm-2 (TOA), +4.5 Wm-2 (atmosphere) and -6.8 Wm-2 (surface), averaged in Asia. In the vertical, monthly forcing is mainly concentrated below 600hPa with maxima around 800hPa. Seasonally, low-level forcing is far larger in dry season than in wet season in South Asia, whereas the wet season forcing exceeds the dry season forcing in East Asia. The anthropogenic forcing in the present study is similar to that in Chung et al.’s [2005] in overall magnitude but the former offers fine-scale features and simulated vertical profiles. The interannual variability of the computed anthropogenic forcing is significant and extremely large over major emission outflow areas. In view of this, the present study’s estimate is within the implicated range of the 1999 INDOEX result. However, NCAR/CCSM3

  20. Measurements of the HO2 uptake coefficient onto aqueous salt and organic aerosols and interpretation using the kinetic multi-layer model of aerosol surface and bulk chemistry (KM-SUB)

    NASA Astrophysics Data System (ADS)

    Matthews, P. S. J.; Berkemeier, T.; George, I. J.; Whalley, L. K.; Moon, D. R.; Ammann, M.; Baeza-Romero, M. T.; Poeschl, U.; Shiraiwa, M.; Heard, D. E.

    2014-12-01

    HO2 is closely coupled with OH which is responsible for the majority of the oxidation in the troposphere. Therefore, it is important to be able to accurately predict OH and HO2 concentrations. However, many studies have reported a large discrepancy between HO2 radical concentrations measured during field campaigns and predicted by constrained box models using detailed chemical mechanisms (1,2). However, there have been very few laboratory studies (3,4) on HO2 uptake by aerosols and the rates and mechanism is still uncertain. The HO2 uptake coefficients were measured for deliquesced ammonium nitrate and sodium chloride aerosols and copper doped sucrose aerosols. The measurements were performed using an aerosol flow tube coupled to a Fluorescence Assay by Gas Expansion (FAGE) detector. By either placing the HO2 injector in set positions and varying the aerosol concentration or by moving it along the flow tube at given aerosol concentrations, uptake coefficients could be measured. The aerosols were generated using an atomiser and the total aerosol surface area was measured using a SMPS. Larger uptake coefficients were measured at shorter times and lower HO2 concentrations for aqueous salt aerosols. The time dependence was able to be modelled by the KM-SUB model (5) as the HO2 concentration decreases along the flow tube and the HO2 uptake mechanism is known to be a second order reaction. Measurements have shown that at higher HO2 concentrations there was also more H2O2 exiting the injector which could convert back to HO2 if trace amounts of metals are present within the aerosol via Fenton reactions. Preliminary results have shown that the inclusion of a Fenton-like reaction within the KM-SUB model has the potential to explain the apparent HO2 concentration dependence. Finally, the KM-SUB model has been used to demonstrate that the increase in uptake coefficient observed when increasing the relative humidity for copper doped sucrose aerosols could be explained by an

  1. Evaluating nitrogen oxide sources and oxidation pathways impacting aerosol production on the Southern Ute Indian Reservation and Navajo Nation using geochemical isotopic analysis

    NASA Astrophysics Data System (ADS)

    King, Michael Z.

    Increased emissions of nitrogen oxides (NOx = NO + NO 2) as a result of the development of oil, gas and coal resources in the Four Corners region of the United States have caused concern for area American Indian tribes that levels of ozone, acid rain, and aerosols or particulate matter (PM) may increase on reservation lands. NOx in the atmosphere plays an important role in the formation of these pollutants and high levels are indicators of poor air quality and exposure to them has been linked to a host of human health effects and environmental problems facing today's society. Nitrogen oxides are eventually oxidized in the atmosphere to form nitrate and nitric acid which falls to earth's surface by way of dry or wet deposition. In the end, it is the removal of NOx from the atmosphere by chemical conversion to nitrate that halts this production of oxidants, acids, and aerosols. Despite the importance of understanding atmospheric nitrate (NO3- = HNO3-(g), NO3-(aq), NO3-(s)) production there remains major deficiencies in estimating the significant key reactions that transform NOx into atmospheric nitrate. Stable isotope techniques have shown that variations in oxygen (16O, 17O, 18O) and nitrogen (14N, 15N) isotope abundances in atmospheric nitrate provide significant insight to the sources and oxidation pathways that transform NOx. Therefore, this project applied this resolution using high pressure liquid chromatography and isotope ratio mass spectrometry to determine the chemical and isotopic composition of particulate nitrate (PM2.5 and PM10), collected on the Southern Ute Indian Reservation and Navajo Nation. It was determined that the observed particulate nitrate concentrations on tribal lands were likely linked to seasonal changes in boundary layer height (BLH), local sources, meteorology, photochemistry and increases in windblown crustal material. The Southern Ute Indian Reservation indicated higher delta15N values in comparison to the Navajo Nation study site

  2. Impacts of Transport Properties of Porous Corrosion Product Layer on Effective Corrosion Rate

    NASA Astrophysics Data System (ADS)

    Li, Xiaobai; Cook, David

    2012-11-01

    Condensing exhaust gases containing H2O, SO3 and NOx cause serious corrosion failure in various industry processes. For example, in modern compact heat cells, corrosion products deposit on top of the heat exchanger cooling fins, blocking the flow passages and drastically decreasing system performance. The transport properties of porous corrosion product layers play important role in determining the corrosion tendency and observed corrosion rate. To understand the corrosion mechanism for Aluminum alloy in sulfuric acid environment, impacts of transport properties of corrosion residual layers are investigated with different numerical models for porous layer diffusivity. The effective corrosion rates resulted from these models are compared to corresponding experimental measurements. A multilayer diffusivity model in which diffusivity depends both on porous layer structure and composition shows excellent agreements with experimental data. This model is currently being used in a multi-scale flow simulation framework to predict corrosion phenomena in heat cells.

  3. 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 aeroso