WorldWideScience

Sample records for surface aerosol measurements

  1. Earth System Research Laboratory Long-Term Surface Aerosol Measurements

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Aerosol measurements began at the NOAA Earth System Research Laboratory (ESRL) Global Monitoring Division (GMD) baseline observatories in the mid-1970's with the...

  2. Aerosol measurements at the Southern Great Plains Site: Design and surface installation

    Energy Technology Data Exchange (ETDEWEB)

    Leifer, R.; Knuth, R.H.; Guggenheim, S.F.; Albert, B. [Department of Energy, New York, NY (United States)

    1996-04-01

    To impropve the predictive capabilities of the Atmospheric Radiation Measurements (ARM) program radiation models, measurements of awserosol size distributions, condensation particle concentrations, aerosol scattering coefficients at a number of wavelenghts, and the aerosol absorption coefficients are needed at the Southern Great Plains (SGP) site. Alos, continuous measurements of ozone concnetrations are needed for model validation. The environmental Measuremenr Laboratory (EMK) has the responsibility to establish the surface aerosol measurements program at the SGP site. EML has designed a special sampling manifold.

  3. In Situ Aerosol Profile Measurements and Comparisons with SAGE 3 Aerosol Extinction and Surface Area Profiles at 68 deg North

    Science.gov (United States)

    2005-01-01

    Under funding from this proposal three in situ profile measurements of stratospheric sulfate aerosol and ozone were completed from balloon-borne platforms. The measured quantities are aerosol size resolved number concentration and ozone. The one derived product is aerosol size distribution, from which aerosol moments, such as surface area, volume, and extinction can be calculated for comparison with SAGE III measurements and SAGE III derived products, such as surface area. The analysis of these profiles and comparison with SAGE III extinction measurements and SAGE III derived surface areas are provided in Yongxiao (2005), which comprised the research thesis component of Mr. Jian Yongxiao's M.S. degree in Atmospheric Science at the University of Wyoming. In addition analysis continues on using principal component analysis (PCA) to derive aerosol surface area from the 9 wavelength extinction measurements available from SAGE III. Ths paper will present PCA components to calculate surface area from SAGE III measurements and compare these derived surface areas with those available directly from in situ size distribution measurements, as well as surface areas which would be derived from PCA and Thomason's algorithm applied to the four wavelength SAGE II extinction measurements.

  4. Study of measurement methods of ultrafine aerosols surface-area for characterizing occupational exposure

    International Nuclear Information System (INIS)

    Bau, S.

    2008-12-01

    This work aims at improving knowledge on ultrafine aerosols surface-area measurement. Indeed, the development of nano-technologies may lead to occupational exposure to airborne nano-structured particles, which involves a new prevention issue. There is currently no consensus concerning what parameter (mass, surface-area, number) should be measured. However, surface-area could be a relevant metric, since it leads to a satisfying correlation with biological effects when nano-structured particles are inhaled. Hence, an original theoretical work was performed to position the parameter of surface-area in relation to other aerosol characteristics. To investigate measurement techniques of nano-structured aerosols surface-area, the experimental facility CAIMAN (Characterization of Instruments for the Measurement of Aerosols of Nano-particles) was designed and built. Within CAIMAN, it is possible to produce nano-structured aerosols with varying and controlled properties (size, concentration, chemical nature, morphology, state-of-charge), stable and reproducible in time. The generated aerosols were used to experimentally characterize the response of the instruments in study (NSAM and AeroTrak 9000 TSI, LQ1-DC Matter Engineering). The response functions measured with monodisperse aerosols show a good agreement with the corresponding theoretical curves in a large size range, from 15 to 520 nm. Furthermore, hypotheses have been formulated to explain the reasonable biases observed when measuring poly-disperse aerosols. (author)

  5. Vertical profiles of aerosol optical properties over central Illinois and comparison with surface and satellite measurements

    Science.gov (United States)

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

    2012-12-01

    Between June 2006 and September 2009, an instrumented light aircraft measured over 400 vertical profiles of aerosol and trace gas properties over eastern and central Illinois. The primary objectives of this program were to (1) measure the in situ aerosol properties and determine their vertical and temporal variability and (2) relate these aircraft measurements to concurrent surface and satellite measurements. The primary profile location was within 15 km of the NOAA/ESRL surface aerosol monitoring station near Bondville, Illinois. Identical instruments at the surface and on the aircraft ensured that the data from both platforms would be directly comparable and permitted a determination of how representative surface aerosol properties were of the lower column. Aircraft profiles were also conducted occasionally at two other nearby locations to increase the frequency of A-Train satellite underflights for the purpose of comparing in situ and satellite-retrieved aerosol data. Measurements of aerosol properties conducted at low relative humidity over the Bondville site compare well with the analogous surface aerosol data and do not indicate any major sampling issues or that the aerosol is radically different at the surface compared with the lowest flyby altitude of ~ 240 m above ground level. Statistical analyses of the in situ vertical profile data indicate that aerosol light scattering and absorption (related to aerosol amount) decreases substantially with increasing altitude. Parameters related to the nature of the aerosol (e.g., single-scattering albedo, Ångström exponent, etc.), however, are relatively constant throughout the mixed layer, and do not vary as much as the aerosol amount throughout the profile. While individual profiles often showed more variability, the median in situ single-scattering albedo was 0.93-0.95 for all sampled altitudes. Several parameters (e.g., submicrometer scattering fraction, hemispheric backscattering fraction, and scattering

  6. Vertical profiles of aerosol optical properties over central Illinois and comparison with surface and satellite measurements

    Directory of Open Access Journals (Sweden)

    P. J. Sheridan

    2012-12-01

    Full Text Available Between June 2006 and September 2009, an instrumented light aircraft measured over 400 vertical profiles of aerosol and trace gas properties over eastern and central Illinois. The primary objectives of this program were to (1 measure the in situ aerosol properties and determine their vertical and temporal variability and (2 relate these aircraft measurements to concurrent surface and satellite measurements. The primary profile location was within 15 km of the NOAA/ESRL surface aerosol monitoring station near Bondville, Illinois. Identical instruments at the surface and on the aircraft ensured that the data from both platforms would be directly comparable and permitted a determination of how representative surface aerosol properties were of the lower column. Aircraft profiles were also conducted occasionally at two other nearby locations to increase the frequency of A-Train satellite underflights for the purpose of comparing in situ and satellite-retrieved aerosol data. Measurements of aerosol properties conducted at low relative humidity over the Bondville site compare well with the analogous surface aerosol data and do not indicate any major sampling issues or that the aerosol is radically different at the surface compared with the lowest flyby altitude of ~ 240 m above ground level. Statistical analyses of the in situ vertical profile data indicate that aerosol light scattering and absorption (related to aerosol amount decreases substantially with increasing altitude. Parameters related to the nature of the aerosol (e.g., single-scattering albedo, Ångström exponent, etc., however, are relatively constant throughout the mixed layer, and do not vary as much as the aerosol amount throughout the profile. While individual profiles often showed more variability, the median in situ single-scattering albedo was 0.93–0.95 for all sampled altitudes. Several parameters (e.g., submicrometer scattering fraction, hemispheric backscattering fraction, and

  7. AeroCom INSITU Project: Comparison of Aerosol Optical Properties from In-situ Surface Measurements and Model Simulations

    Science.gov (United States)

    Schmeisser, L.; Andrews, E.; Schulz, M.; Fiebig, M.; Zhang, K.; Randles, C. A.; Myhre, G.; Chin, M.; Stier, P.; Takemura, T.; Krol, M. C.; Bian, H.; Skeie, R. B.; da Silva, A. M., Jr.; Kokkola, H.; Laakso, A.; Ghan, S.; Easter, R. C.

    2015-12-01

    AeroCom, an open international collaboration of scientists seeking to improve global aerosol models, recently initiated a project comparing model output to in-situ, surface-based measurements of aerosol optical properties. The model/measurement comparison project, called INSITU, aims to evaluate the performance of a suite of AeroCom aerosol models with site-specific observational data in order to inform iterative improvements to model aerosol modules. Surface in-situ data have the unique property of being traceable to physical standards, which is a big asset in accomplishing the overarching goal of bettering the accuracy of aerosol processes and predicative capability of global climate models. The INSITU project looks at how well models reproduce aerosol climatologies on a variety of time scales, aerosol characteristics and behaviors (e.g., aerosol persistence and the systematic relationships between aerosol optical properties), and aerosol trends. Though INSITU is a multi-year endeavor, preliminary phases of the analysis, using GOCART and other models participating in this AeroCom project, show substantial model biases in absorption and scattering coefficients compared to surface measurements, though the sign and magnitude of the bias varies with location and optical property. Spatial patterns in the biases highlight model weaknesses, e.g., the inability of models to properly simulate aerosol characteristics at sites with complex topography (see Figure 1). Additionally, differences in modeled and measured systematic variability of aerosol optical properties suggest that some models are not accurately capturing specific aerosol co-dependencies, for example, the tendency of in-situ surface single scattering albedo to decrease with decreasing aerosol extinction coefficient. This study elucidates specific problems with current aerosol models and suggests additional model runs and perturbations that could further evaluate the discrepancies between measured and modeled

  8. Retrieval and Validation of aerosol optical properties from AHI measurements: impact of surface reflectance assumption

    Science.gov (United States)

    Lim, H.; Choi, M.; Kim, J.; Go, S.; Chan, P.; Kasai, Y.

    2017-12-01

    This study attempts to retrieve the aerosol optical properties (AOPs) based on the spectral matching method, with using three visible and one near infrared channels (470, 510, 640, 860nm). This method requires the preparation of look-up table (LUT) approach based on the radiative transfer modeling. Cloud detection is one of the most important processes for guaranteed quality of AOPs. Since the AHI has several infrared channels, which are very advantageous for cloud detection, clouds can be removed by using brightness temperature difference (BTD) and spatial variability test. The Yonsei Aerosol Retrieval (YAER) algorithm is basically utilized on a dark surface, therefore a bright surface (e.g., desert, snow) should be removed first. Then we consider the characteristics of the reflectance of land and ocean surface using three visible channels. The known surface reflectivity problem in high latitude area can be solved in this algorithm by selecting appropriate channels through improving tests. On the other hand, we retrieved the AOPs by obtaining the visible surface reflectance using NIR to normalized difference vegetation index short wave infrared (NDVIswir) relationship. ESR tends to underestimate urban and cropland area, we improved the visible surface reflectance considering urban effect. In this version, ocean surface reflectance is using the new cox and munk method which considers ocean bidirectional reflectance distribution function (BRDF). Input of this method has wind speed, chlorophyll, salinity and so on. Based on validation results with the sun-photometer measurement in AErosol Robotic NETwork (AERONET), we confirm that the quality of Aerosol Optical Depth (AOD) from the YAER algorithm is comparable to the product from the Japan Aerospace Exploration Agency (JAXA) retrieval algorithm. Our future update includes a consideration of improvement land surface reflectance by hybrid approach, and non-spherical aerosols. This will improve the quality of YAER

  9. Deriving aerosol properties from measurements of the Atmosphere-Surface Radiation Automatic Instrument (ASRAI)

    Science.gov (United States)

    Xu, Hua; Li, Donghui; Li, Zhengqiang; Zheng, Xiaobing; Li, Xin; Xie, Yisong; Liu, Enchao

    2015-10-01

    The Atmosphere-surface Radiation Automatic Instrument (ASRAI) is a newly developed hyper-spectral apparatus by Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences (AIOFM, CAS), measuring total spectral irradiance, diffuse spectral irradiance of atmosphere and reflected radiance of the land surface for the purpose of in-situ calibration. The instrument applies VIS-SWIR spectrum (0.4~1.0 μm) with an averaged spectral resolution of 0.004 μm. The goal of this paper is to describe a method of deriving both aerosol optical depth (AOD) and aerosol modes from irradiance measurements under free cloudy conditions. The total columnar amounts of water vapor and oxygen are first inferred from solar transmitted irradiance at strong absorption wavelength. The AOD together with total columnar amounts of ozone and nitrogen dioxide are determined by a nonlinear least distance fitting method. Moreover, it is able to infer aerosol modes from the spectral dependency of AOD because different aerosol modes have their inherent spectral extinction characteristics. With assumption that the real aerosol is an idea of "external mixing" of four basic components, dust-like, water-soluble, oceanic and soot, the percentage of volume concentration of each component can be retrieved. A spectrum matching technology based on Euclidean-distance method is adopted to find the most approximate combination of components. The volume concentration ratios of four basic components are in accordance with our prior knowledge of regional aerosol climatology. Another advantage is that the retrievals would facilitate the TOA simulation when applying 6S model for satellite calibration.

  10. Comparison of diffusion charging and mobility-based methods for measurement of aerosol agglomerate surface area.

    Science.gov (United States)

    Ku, Bon Ki; Kulkarni, Pramod

    2012-05-01

    We compare different approaches to measure surface area of aerosol agglomerates. The objective was to compare field methods, such as mobility and diffusion charging based approaches, with laboratory approach, such as Brunauer, Emmett, Teller (BET) method used for bulk powder samples. To allow intercomparison of various surface area measurements, we defined 'geometric surface area' of agglomerates (assuming agglomerates are made up of ideal spheres), and compared various surface area measurements to the geometric surface area. Four different approaches for measuring surface area of agglomerate particles in the size range of 60-350 nm were compared using (i) diffusion charging-based sensors from three different manufacturers, (ii) mobility diameter of an agglomerate, (iii) mobility diameter of an agglomerate assuming a linear chain morphology with uniform primary particle size, and (iv) surface area estimation based on tandem mobility-mass measurement and microscopy. Our results indicate that the tandem mobility-mass measurement, which can be applied directly to airborne particles unlike the BET method, agrees well with the BET method. It was also shown that the three diffusion charging-based surface area measurements of silver agglomerates were similar within a factor of 2 and were lower than those obtained from the tandem mobility-mass and microscopy method by a factor of 3-10 in the size range studied. Surface area estimated using the mobility diameter depended on the structure or morphology of the agglomerate with significant underestimation at high fractal dimensions approaching 3.

  11. AEROSOL AND GAS MEASUREMENT

    Science.gov (United States)

    Measurements provide fundamental information for evaluating and managing the impact of aerosols on air quality. Specific measurements of aerosol concentration and their physical and chemical properties are required by different users to meet different user-community needs. Befo...

  12. Error sources in the retrieval of aerosol information over bright surfaces from satellite measurements in the oxygen A band

    Science.gov (United States)

    Nanda, Swadhin; de Graaf, Martin; Sneep, Maarten; de Haan, Johan F.; Stammes, Piet; Sanders, Abram F. J.; Tuinder, Olaf; Pepijn Veefkind, J.; Levelt, Pieternel F.

    2018-01-01

    Retrieving aerosol optical thickness and aerosol layer height over a bright surface from measured top-of-atmosphere reflectance spectrum in the oxygen A band is known to be challenging, often resulting in large errors. In certain atmospheric conditions and viewing geometries, a loss of sensitivity to aerosol optical thickness has been reported in the literature. This loss of sensitivity has been attributed to a phenomenon known as critical surface albedo regime, which is a range of surface albedos for which the top-of-atmosphere reflectance has minimal sensitivity to aerosol optical thickness. This paper extends the concept of critical surface albedo for aerosol layer height retrievals in the oxygen A band, and discusses its implications. The underlying physics are introduced by analysing the top-of-atmosphere reflectance spectrum as a sum of atmospheric path contribution and surface contribution, obtained using a radiative transfer model. Furthermore, error analysis of an aerosol layer height retrieval algorithm is conducted over dark and bright surfaces to show the dependence on surface reflectance. The analysis shows that the derivative with respect to aerosol layer height of the atmospheric path contribution to the top-of-atmosphere reflectance is opposite in sign to that of the surface contribution - an increase in surface brightness results in a decrease in information content. In the case of aerosol optical thickness, these derivatives are anti-correlated, leading to large retrieval errors in high surface albedo regimes. The consequence of this anti-correlation is demonstrated with measured spectra in the oxygen A band from the GOME-2 instrument on board the Metop-A satellite over the 2010 Russian wildfires incident.

  13. Seasonal differences in aerosol water may reconcile AOT and surface mass measurements in the Southeast U.S.

    Science.gov (United States)

    Nguyen, T. K. V.; Ghate, V. P.; Carlton, A. M. G.

    2015-12-01

    Summertime aerosol optical thickness (AOT) in the Southeast U.S. is high and sharply enhanced (2-3 times) compared to wintertime AOT. This seasonal pattern is unique to the Southeast U.S. and is of particular interest because temperatures there have not warmed over the past 100 years, contrasting with trends in other U.S. regions. Some investigators hypothesize the Southeast temperature trend is due to secondary organic aerosols (SOA) formed from interactions of biogenic volatile organic compounds (BVOCs) and anthropogenic emissions that create a cooling haze. However, aerosol measurements made at the surface do not exhibit strong seasonal differences in mass or organic fraction to support this hypothesis. In this work, we attempt to reconcile the spatial and temporal distribution of AOT over the U.S. with surface mass measurements by examining trends in particle-phase liquid water, an aerosol constituent that effectively scatters radiation and is removed from aerosols in mass measurements at routine surface monitoring sites. We employ the thermodynamic model ISORROPIA (v2.1) to estimate surface and aloft aerosol water mass concentrations at locations of Interagency Monitoring of Protected Visual Environments (IMPROVE) sites using measured speciated ion mass concentrations and NCEP North American Regional Reanalysis (NARR) meteorological data. Results demonstrate strong seasonal differences in aerosol water in the eastern compared to the western part of the U.S., consistent with geographic patterns in AOT. The highest mean regional seasonal difference from 2000 to 2007 is 5.5 μg m-3 and occurs the Southeast, while the lowest is 0.44 μg m-3 and occurs in the dry Mountain West. Our findings suggest 1) similarity between spatial trends in aerosol water in the U.S. and previously published AOT data from the MODIS-TERRA instrument and 2) similar interannual trends in mean aerosol water and previously published interannual AOT trends from MISR, MODIS-TERRA, MODIS

  14. Simultaneous retrieval of aerosol and surface optical properties from combined airborne- and ground-based direct and diffuse radiometric measurements

    Directory of Open Access Journals (Sweden)

    C. K. Gatebe

    2010-03-01

    Full Text Available This paper presents a new method for simultaneously retrieving aerosol and surface reflectance properties from combined airborne and ground-based direct and diffuse radiometric measurements. The method is based on the standard Aerosol Robotic Network (AERONET method for retrieving aerosol size distribution, complex index of refraction, and single scattering albedo, but modified to retrieve aerosol properties in two layers, below and above the aircraft, and parameters on surface optical properties from combined datasets (Cloud Absorption Radiometer (CAR and AERONET data. A key advantage of this method is the inversion of all available spectral and angular data at the same time, while accounting for the influence of noise in the inversion procedure using statistical optimization. The wide spectral (0.34–2.30 μm and angular range (180° of the CAR instrument, combined with observations from an AERONET sunphotometer, provide sufficient measurement constraints for characterizing aerosol and surface properties with minimal assumptions. The robustness of the method was tested on observations made during four different field campaigns: (a the Southern African Regional Science Initiative 2000 over Mongu, Zambia, (b the Intercontinental Transport Experiment-Phase B over Mexico City, Mexico (c Cloud and Land Surface Interaction Campaign over the Atmospheric Radiation Measurement (ARM Central Facility, Oklahoma, USA, and (d the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS over Elson Lagoon in Barrow, Alaska, USA. The four areas are dominated by different surface characteristics and aerosol types, and therefore provide good test cases for the new inversion method.

  15. Aerosol Direct Radiative Forcing and Forcing Efficiencies at Surface from the shortwave Irradiance Measurements in Abu Dhabi, UAE

    Science.gov (United States)

    Beegum S, N.; Ben Romdhane, H.; Ghedira, H.

    2013-12-01

    Atmospheric aerosols are known to affect the radiation balance of the Earth-Atmospheric system directly by scattering and absorbing the solar and terrestrial radiation, and indirectly by affecting the lifetime and albedo of the clouds. Continuous and simultaneous measurements of short wave global irradiance in combination with synchronous spectral aerosol optical depth (AOD) measurements (from 340 nm to 1640 nm in 8 channels), for a period of 1 year from June 2012 to May 2013, were used for the determination of the surface direct aerosol radiative forcing and forcing efficiencies under cloud free conditions in Abu Dhabi (24.42°N, 54.61o E, 7m MSL), a coastal location in United Arab Emirates (UAE) in the Arabian Peninsula. The Rotating Shadow band Pyranometer (RSP, LI-COR) was used for the irradiance measurements (in the spectral region 400-1100 nm), whereas the AOD measurements were carried out using CIMEL Sunphotometer (CE 318-2, under AERONET program). The differential method, which is neither sensitive to calibration uncertainties nor model assumptions, has been employed for estimating forcing efficiencies from the changes in the measured fluxes. The forcing efficiency, which quantifies the net change in irradiance per unit change in AOD, is an appropriate parameter for the characterization of the aerosol radiative effects even if the microphysical and optical properties of the aerosols are not completely understood. The corresponding forcing values were estimated from the forcing efficiencies. The estimated radiative forcing and forcing efficiencies exhibited strong monthly variations. The forcing efficiencies (absolute magnitudes) were highest during March, and showed continuous decrease thereafter to reach the lowest value during September. In contrast, the forcing followed a slightly different pattern of variability, with the highest solar dimming during April ( -60 W m-2) and the minimum during February ( -20 W m-2). The results indicate that the aerosol

  16. An automated analyzer to measure surface-atmosphere exchange fluxes of water soluble inorganic aerosol compounds and reactive trace gases.

    Science.gov (United States)

    Thomas, Rick M; Trebs, Ivonne; Otjes, René; Jongejan, Piet A C; Ten Brink, Harry; Phillips, Gavin; Kortner, Michael; Meixner, Franz X; Nemitz, Eiko

    2009-03-01

    Here, we present a new automated instrument for semicontinuous gradient measurements of water-soluble reactive trace gas species (NH3, HNO3, HONO, HCl, and SO2) and their related aerosol compounds (NH4+, NO3-, Cl-, SO4(2-)). Gas and aerosol samples are collected simultaneously at two heights using rotating wet-annular denuders and steam-jet aerosol collectors, respectively. Online (real-time) analysis using ion chromatography (IC) for anions and flow injection analysis (FIA) for NH4+ and NH3 provide a half-hourly averaged gas and aerosol gradients within each hour. Through the use of syringe pumps, IC preconcentration columns, and high-quality purified water, the system achieves detection limits (3sigma-definition) under field conditions of typically: 136/207,135/114, 29/ 22,119/92, and 189/159 ng m(-3) for NH3/NH4+, HNO3/NO3-, HONO/ NO2-, HCl/Cl- and SO2/SO4(2-), respectively. The instrument demonstrates very good linearity and accuracy for liquid and selected gas phase calibrations over typical ambient concentration ranges. As shown by examples from field experiments, the instrument provides sufficient precision (3-9%), even at low ambient concentrations, to resolve vertical gradients and calculate surface-atmosphere exchange fluxes undertypical meteorological conditions of the atmospheric surface layer using the aerodynamic gradient technique.

  17. Use of In Situ Cloud Condensation Nuclei, Extinction, and Aerosol Size Distribution Measurements to Test a Method for Retrieving Cloud Condensation Nuclei Profiles From Surface Measurements

    Science.gov (United States)

    Ghan, Stephen J.; Rissman, Tracey A.; Ellman, Robert; Ferrare, Richard A.; Turner, David; Flynn, Connor; Wang, Jian; Ogren, John; Hudson, James; Jonsson, Haflidi H.; hide

    2006-01-01

    If the aerosol composition and size distribution below cloud are uniform, the vertical profile of cloud condensation nuclei (CCN) concentration can be retrieved entirely from surface measurements of CCN concentration and particle humidification function and surface-based retrievals of relative humidity and aerosol extinction or backscatter. This provides the potential for long-term measurements of CCN concentrations near cloud base. We have used a combination of aircraft, surface in situ, and surface remote sensing measurements to test various aspects of the retrieval scheme. Our analysis leads us to the following conclusions. The retrieval works better for supersaturations of 0.1% than for 1% because CCN concentrations at 0.1% are controlled by the same particles that control extinction and backscatter. If in situ measurements of extinction are used, the retrieval explains a majority of the CCN variance at high supersaturation for at least two and perhaps five of the eight flights examined. The retrieval of the vertical profile of the humidification factor is not the major limitation of the CCN retrieval scheme. Vertical structure in the aerosol size distribution and composition is the dominant source of error in the CCN retrieval, but this vertical structure is difficult to measure from remote sensing at visible wavelengths.

  18. Size segregated aerosol mass concentration measurements over ...

    Indian Academy of Sciences (India)

    Mass concentration and mass size distribution of total (composite) aerosols near the surface are essential inputs needed in developing aerosol models for radiative forcing estimation as well as to infer the environment and air quality. Using extensive measurements onboard the oceanographic research vessel, Sagar Kanya ...

  19. Impacts of Aerosol Direct Effects on the South Asian Climate: Assessment of Radiative Feedback Processes Using Model Simulations and Satellite/Surface Measurements

    Science.gov (United States)

    Wang, Sheng-Hsiang; Gautam, Ritesh; Lau, William K. M.; Tsay, Si-Chee; Sun, Wen-Yih; Kim, Kyu-Myong; Chern, Jiun-Dar; Hsu, Christina; Lin, Neng-Huei

    2011-01-01

    Current assessment of aerosol radiative effect is hindered by our incomplete knowledge of aerosol optical properties, especially absorption, and our current inability to quantify physical and microphysical processes. In this research, we investigate direct aerosol radiative effect over heavy aerosol loading areas (e.g., Indo-Gangetic Plains, South/East Asia) and its feedbacks on the South Asian climate during the pre-monsoon season (March-June) using the Purdue Regional Climate Model (PRCM) with prescribed aerosol data derived by the NASA Goddard Earth Observing System Model (GEOS-5). Our modeling domain covers South and East Asia (60-140E and 0-50N) with spatial resolutions of 45 km in horizontal and 28 layers in vertical. The model is integrated from 15 February to 30 June 2008 continuously without nudging (i.e., only forced by initial/boundary conditions). Two numerical experiments are conducted with and without the aerosol-radiation effects. Both simulations are successful in reproducing the synoptic patterns on seasonal-to-interannual time scales and capturing a pre-monsoon feature of the northward rainfall propagation over Indian region in early June which shown in Tropical Rainfall Measuring Mission (TRMM) observation. Preliminary result suggests aerosol-radiation interactions mainly alter surface-atmosphere energetics and further result in an adjustment of the vertical temperature distribution in lower atmosphere (below 700 hPa). The modifications of temperature and associated rainfall and circulation feedbacks on the regional climate will be discussed in the presentation.

  20. Direct Measurements of Surface Energy, Elastic Modulus and Interparticle Forces of Titan Aerosol Analog (`Tholin') Using Atomic Force Microscopy

    Science.gov (United States)

    Yu, X.; Horst, S. M.; He, C.; McGuiggan, P.; Bridges, N. T.

    2017-12-01

    To understand the origin of the dunes on Titan, it is important to investigate the material properties of the sand particles on Titan, which are mainly made of organics deposited from the atmosphere [1]. The organic sand may behave differently compared to the quartz/basaltic sand on terrestrial planets (Earth, Venus, Mars) in terms of interparticle forces. We measured the surface energy (through contact angle measurements) and elastic modulus (through Atomic Force Microscopy, AFM) of Titan aerosol analog (tholins) produced in our lab. Tholins may be compositionally similar to sand on Titan. We directly measured the interparticle forces between a tholin particle adhered to an AFM cantilver and tholin particles on a substrate. We also measured the properties of walnut shells, a typical material used in the Titan Wind Tunnel (TWT, [2, 3]). We find the surface energy of a tholin thin film is about 70.9 mN/m and its elastic modulus is about 3.5 GPa (similar to hard polymers like PMMA and polystyrene). We used the two measured material properties of tholin to calculate its interparticle cohesion assuming simple sphere-sphere geometry [4]. For two 20 µm particles, the theoretical cohesion force is about 6682 nN. Under dry nitrogen (RHmeasured interparticle forces using AFM was approximately 4000 nN, which is smaller than theoretical predictions but still relatively strong under dry conditions. The interparticle cohesion between walnut shell particles is only 200 nN, which is much lower than between tholin particles. The key finding of this study is that the interparticle cohesion forces are much larger for tholins and presumably Titan sand particles than for terrestrial sand and materials used in the wind tunnel. This suggests we should increase the interparticle force in both analog experiments (TWT) and threshold models (e.g. [5]) to correctly translate the results to real Titan conditions. The strong cohesion of tholins may also inform us how the small aerosol

  1. Satellite Remote Sensing: Aerosol Measurements

    Science.gov (United States)

    Kahn, Ralph A.

    2013-01-01

    Aerosols are solid or liquid particles suspended in the air, and those observed by satellite remote sensing are typically between about 0.05 and 10 microns in size. (Note that in traditional aerosol science, the term "aerosol" refers to both the particles and the medium in which they reside, whereas for remote sensing, the term commonly refers to the particles only. In this article, we adopt the remote-sensing definition.) They originate from a great diversity of sources, such as wildfires, volcanoes, soils and desert sands, breaking waves, natural biological activity, agricultural burning, cement production, and fossil fuel combustion. They typically remain in the atmosphere from several days to a week or more, and some travel great distances before returning to Earth's surface via gravitational settling or washout by precipitation. Many aerosol sources exhibit strong seasonal variability, and most experience inter-annual fluctuations. As such, the frequent, global coverage that space-based aerosol remote-sensing instruments can provide is making increasingly important contributions to regional and larger-scale aerosol studies.

  2. Comparison of Aerosol Volume Size Distributions between Surface and Ground-based Remote Sensing Measurements Downwind of Seoul, Korea during MAPS-Seoul

    Science.gov (United States)

    Kim, P.; Choi, Y.; Ghim, Y. S.

    2016-12-01

    Both sunphotometer (Cimel, CE-318) and skyradiometer (Prede, POM-02) were operated in May, 2015 as a part of the Megacity Air Pollution Studies-Seoul (MAPS-Seoul) campaign. These instruments were collocated at the Hankuk University of Foreign Studies (Hankuk_UFS) site of AErosol RObotic NETwork (AERONET) and the Yongin (YGN) site of SKYradiometer NETwork (SKYNET). The aerosol volume size distribution at the surface was measured using a wide range aerosol spectrometer (WRAS) system consisting of a scanning mobility particle sizer (Grimm, Model 5.416; 45 bins, 0.01-1.09 μm) and an optical particle counter (Grimm, Model 1.109; 31 bins, 0.27-34 μm). The measurement site (37.34oN, 127.27oE, 167 m above sea level) is located about 35 km southeast of downtown Seoul. To investigate the discrepancies in volume concentrations, effective diameters and fine mode volume fractions, we compared the volume size distributions from sunphotometer, skyradiometer, and WRAS system when the measurement time coincided within 5 minutes considering that the measurement intervals were different between instruments.

  3. Aerosol Absorption Measurements in MILAGRO.

    Science.gov (United States)

    Gaffney, J. S.; Marley, N. A.; Arnott, W. P.; Paredes-Miranda, L.; Barnard, J. C.

    2007-12-01

    During the month of March 2006, a number of instruments were used to determine the absorption characteristics of aerosols found in the Mexico City Megacity and nearby Valley of Mexico. These measurements were taken as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City (MAX-Mex) that was carried out in collaboration with the Megacity Interactions: Local and Global Research Observations (MILAGRO) campaign. MILAGRO was a joint effort between the DOE, NSF, NASA, and Mexican agencies aimed at understanding the impacts of a megacity on the urban and regional scale. A super-site was operated at the Instituto Mexicano de Petroleo in Mexico City (designated T-0) and at the Universidad Technologica de Tecamac (designated T-1) that was located about 35 km to the north east of the T-0 site in the State of Mexico. A third site was located at a private rancho in the State of Hidalgo approximately another 35 km to the northeast (designated T-2). Aerosol absorption measurements were taken in real time using a number of instruments at the T-0 and T-1 sites. These included a seven wavelength aethalometer, a multi-angle absorption photometer (MAAP), and a photo-acoustic spectrometer. Aerosol absorption was also derived from spectral radiometers including a multi-filter rotating band spectral radiometer (MFRSR). The results clearly indicate that there is significant aerosol absorption by the aerosols in the Mexico City megacity region. The absorption can lead to single scattering albedo reduction leading to values below 0.5 under some circumstances. The absorption is also found to deviate from that expected for a "well-behaved" soot anticipated from diesel engine emissions, i.e. from a simple 1/lambda wavelength dependence for absorption. Indeed, enhanced absorption is seen in the region of 300-450 nm in many cases, particularly in the afternoon periods indicating that secondary organic aerosols are contributing to the aerosol absorption. This is likely due

  4. Miniature Sensor for Aerosol Mass Measurements Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR project seeks to develop a miniature sensor for mass measurement of size-classified aerosols. A cascade impactor will be used to classify aerosol sample...

  5. Aerosol Observing System Surface Meteorology (AOSMET) Instrument Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Kyrouac, J. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-04-01

    The U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility Aerosol Observing System (AOS) surface meteorology instrument is an ancillary sensor that provides temperature, relative humidity, pressure, wind speed and direction, and precipitation data relevant to the AOS. It consists of a Vaisala WXT520 Weather Transmitter mounted on top of the AOS aerosol inlet, at a height of approximately 10 meters.

  6. A comprehensive evaluation of water uptake on atmospherically relevant mineral surfaces: DRIFT spectroscopy, thermogravimetric analysis and aerosol growth measurements

    Directory of Open Access Journals (Sweden)

    R. J. Gustafsson

    2005-01-01

    Full Text Available The hygroscopicity of mineral aerosol samples has been examined by three independent methods: diffuse reflectance infrared Fourier transform spectroscopy, thermogravimetric analysis and differential mobility analysis. All three methods allow an evaluation of the water coverage of two samples, CaCO3 and Arizona Test dust, as a function of relative humidity. For the first time, a correlation between absolute gravimetric measurements and the other two (indirect methods has been established. Water uptake isotherms were reliably determined for both solids which at 298 K and 80% relative humidity exhibited similar coverages of ~4 monolayers. However, the behaviour at low relative humidity was markedly different in the two cases, with Arizona Test Dust showing a substantially higher affinity for water in the contact layer. This is understandable in terms of the chemical composition of these two materials. The mobility analysis results are in good accord with field observations and with our own spectroscopic and gravimetric measurements. These findings are of value for an understanding of atmospheric chemical processes.

  7. Global estimate of aerosol direct radiative forcing from satellite measurements.

    Science.gov (United States)

    Bellouin, Nicolas; Boucher, Olivier; Haywood, Jim; Reddy, M Shekar

    2005-12-22

    Atmospheric aerosols cause scattering and absorption of incoming solar radiation. Additional anthropogenic aerosols released into the atmosphere thus exert a direct radiative forcing on the climate system. The degree of present-day aerosol forcing is estimated from global models that incorporate a representation of the aerosol cycles. Although the models are compared and validated against observations, these estimates remain uncertain. Previous satellite measurements of the direct effect of aerosols contained limited information about aerosol type, and were confined to oceans only. Here we use state-of-the-art satellite-based measurements of aerosols and surface wind speed to estimate the clear-sky direct radiative forcing for 2002, incorporating measurements over land and ocean. We use a Monte Carlo approach to account for uncertainties in aerosol measurements and in the algorithm used. Probability density functions obtained for the direct radiative forcing at the top of the atmosphere give a clear-sky, global, annual average of -1.9 W m(-2) with standard deviation, +/- 0.3 W m(-2). These results suggest that present-day direct radiative forcing is stronger than present model estimates, implying future atmospheric warming greater than is presently predicted, as aerosol emissions continue to decline.

  8. Importance of Raman Lidar Aerosol Extinction Measurements for Aerosol-Cloud Interaction Studies

    Directory of Open Access Journals (Sweden)

    Han Zaw

    2016-01-01

    Full Text Available Using a UV Raman Lidar for aerosol extinction, and combining Microwave Radiometer derived Liquid Water Path (LWP with Multifilter Rotating Shadowband Radiometer derived Cloud Optical depth, to get cloud effective radius (Reff, we observe under certain specialized conditions, clear signatures of the Twomey Aerosol Indirect effect on cloud droplet properties which are consistent with the theoretical bounds. We also show that the measurement is very sensitive to how far the aerosol layer is from the cloud base and demonstrate that surface PM25 is far less useful. Measurements from both the DOE ARM site and new results at CCNY are presented.

  9. Aerosol optical absorption measurements with photoacoustic spectroscopy

    Science.gov (United States)

    Liu, Kun; Wang, Lei; Liu, Qiang; Wang, Guishi; Tan, Tu; Zhang, Weijun; Chen, Weidong; Gao, Xiaoming

    2015-04-01

    Many parameters related to radiative forcing in climate research are known only with large uncertainties. And one of the largest uncertainties in global radiative forcing is the contribution from aerosols. Aerosols can scatter or absorb the electromagnetic radiation, thus may have negative or positive effects on the radiative forcing of the atmosphere, respectively [1]. And the magnitude of the effect is directly related to the quantity of light absorbed by aerosols [2,3]. Thus, sensitivity and precision measurement of aerosol optical absorption is crucial for climate research. Photoacoustic spectroscopy (PAS) is commonly recognized as one of the best candidates to measure the light absorption of aerosols [4]. A PAS based sensor for aerosol optical absorption measurement was developed. A 532 nm semiconductor laser with an effective power of 160 mW was used as a light source of the PAS sensor. The PAS sensor was calibrated by using known concentration NO2. The minimum detectable optical absorption coefficient (OAC) of aerosol was determined to be 1 Mm-1. 24 hours continues measurement of OAC of aerosol in the ambient air was carried out. And a novel three wavelength PAS aerosol OAC sensor is in development for analysis of aerosol wavelength-dependent absorption Angstrom coefficient. Reference [1] U. Lohmann and J. Feichter, Global indirect aerosol effects: a review, Atmos. Chem. Phys. 5, 715-737 (2005) [2] M. Z. Jacobson, Strong radiative heating due to the mixing state of black carbon in atmospheric aerosols, Nature 409, 695-697 (2001) [3] V. Ramanathan and G. Carmichae, Global and regional climate changes due to black carbon, nature geoscience 1, 221-227 (2008) [4] W.P Arnott, H. Moosmuller, C. F. Rogers, T. Jin, and R. Bruch, Photoacoustic spectrometer for measuring light absorption by aerosol: instrument description. Atmos. Environ. 33, 2845-2852 (1999).

  10. A case study on biomass burning aerosols: effects on aerosol optical properties and surface radiation levels

    Directory of Open Access Journals (Sweden)

    A. Arola

    2007-08-01

    Full Text Available In spring 2006, biomass burning aerosols from eastern Europe were transported extensively to Finland, and to other parts of northern Europe. They were observed as far as in the European Arctic. In the first part of this paper, temporal and spatial evolution and transport of these biomass burning aerosols are monitored with MODIS retrieved aerosol optical depth (AOD imagery at visible wavelengths (0.55 μm. Comparison of MODIS and AERONET AOD is conducted at Tõravere, Estonia. Then trajectory analyses, as well as MODIS Fire Mapper products are used to better understand the type and origin of the air masses. During the studied four-week period AOD values ranged from near zero up to 1.2 at 0.55 μm and the linear correlation between MODIS and AERONET was very high (~0.97. Temporal variability observed within this four-week period was also rather well explained by the trajectory analysis in conjunction with the fire detections produced by the MODIS Rapid Response System. In the second part of our study, the surface measurements of global and UV radiation at Jokioinen, Finland are used to study the effect of this haze episode on the levels of surface radiation. We found reductions up to 35% in noon-time surface UV irradiance (at 340 nm as compared to typical aerosol conditions. For global (total solar radiation, the reduction was always smaller, in line with the expected wavelength dependence of the aerosol effect.

  11. AeroCom INSITU Project: Comparing modeled and measured aerosol optical properties

    Science.gov (United States)

    Andrews, Elisabeth; Schmeisser, Lauren; Schulz, Michael; Fiebig, Markus; Ogren, John; Bian, Huisheng; Chin, Mian; Easter, Richard; Ghan, Steve; Kokkola, Harri; Laakso, Anton; Myhre, Gunnar; Randles, Cynthia; da Silva, Arlindo; Stier, Phillip; Skeie, Ragnehild; Takemura, Toshihiko; van Noije, Twan; Zhang, Kai

    2016-04-01

    AeroCom, an open international collaboration of scientists seeking to improve global aerosol models, recently initiated a project comparing model output to in-situ, surface-based measurements of aerosol optical properties. The model/measurement comparison project, called INSITU, aims to evaluate the performance of a suite of AeroCom aerosol models with site-specific observational data in order to inform iterative improvements to model aerosol modules. Surface in-situ data has the unique property of being traceable to physical standards, which is an asset in accomplishing the overall goal of bettering the accuracy of aerosols processes and the predicative capability of global climate models. Here we compare dry, in-situ aerosol scattering and absorption data from ~75 surface, in-situ sites from various global aerosol networks (including NOAA, EUSAAR/ACTRIS and GAW) with a simulated optical properties from a suite of models participating in the AeroCom project. We report how well models reproduce aerosol climatologies for a variety of time scales, aerosol characteristics and behaviors (e.g., aerosol persistence and the systematic relationships between aerosol optical properties), and aerosol trends. Though INSITU is a multi-year endeavor, preliminary phases of the analysis suggest substantial model biases in absorption and scattering coefficients compared to surface measurements, though the sign and magnitude of the bias varies with location. Spatial patterns in the biases highlight model weaknesses, e.g., the inability of models to properly simulate aerosol characteristics at sites with complex topography. Additionally, differences in modeled and measured systematic variability of aerosol optical properties suggest that some models are not accurately capturing specific aerosol behaviors, for example, the tendency of in-situ single scattering albedo to decrease with decreasing aerosol extinction coefficient. The endgoal of the INSITU project is to identify specific

  12. In Situ Measurement of Aerosol Extinction

    Science.gov (United States)

    Strawa, Anthony W.; Castaneda, R.; Owano, T. G.; Bear, D.; Gore, Warren J. (Technical Monitor)

    2001-01-01

    Aerosols are important contributors to the radiative forcing in the atmosphere. Much of the uncertainty in our knowledge of climate forcing is due to uncertainties in the radiative forcing due to aerosols as illustrated in the IPCC reports of the last ten years. Improved measurement of aerosol optical properties, therefore, is critical to an improved understanding of atmospheric radiative forcing. Additionally, attempts to reconcile in situ and remote measurements of aerosol radiative properties have generally not been successful. This is due in part to the fact that it has been impossible to measure aerosol extinction in situ in the past. In this presentation we introduce a new instrument that employs the techniques used in cavity ringdown spectroscopy to measure the aerosol extinction and scattering coefficients in situ. A prototype instrument has been designed and tested in the lab and the field. It is capable of measuring aerosol extinction coefficient to 2x10(exp -6) per meter. This prototype instrument is described and results are presented.

  13. Gas-phase removal of biofilms from various surfaces using carbon dioxide aerosols.

    Science.gov (United States)

    Cha, Minju; Hong, Seongkyeol; Kang, Min-Yeong; Lee, Jin-Won; Jang, Jaesung

    2012-01-01

    The present study evaluated the removal of Escherichia coli XL1-blue biofilms using periodic jets of carbon dioxide aerosols (a mixture of solid and gaseous CO(2)) with nitrogen gas. The aerosols were generated by the adiabatic expansion of high-pressure CO(2) gas through a nozzle and used to remove air-dried biofilms. The areas of the biofilms were measured from scanning electron micrographs before and after applying the aerosols. The removal efficiency of the aerosol treatment was measured with various air-drying times of the biofilms before the treatment, surface materials, and durations of CO(2) aerosols in each 8-s aerosol-nitrogen cleaning cycle. Nearly 100% of the fresh biofilms were removed from the various surfaces very reliably within 90 s. This technique can be useful for removing unsaturated biofilms on solid surfaces and has potential applications for cleaning bio-contaminated surfaces.

  14. Radiative Properties of Smoke and Aerosol Over Land Surfaces

    Science.gov (United States)

    King, Michael D.

    2000-01-01

    This talk discusses smoke and aerosol's radiative properties with particular attention to distinguishing the measurement over clear sky from clouds over land, sea, snow, etc. surfaces, using MODIS Airborne Simulator data from (Brazil, arctic sea ice and tundra and southern Africa, west Africa, and other ecosystems. This talk also discusses the surface bidirectional reflectance using Cloud Absorption Radiometer, BRDF measurements of Saudi Arabian desert, Persian Gulf, cerrado and rain forests in Brazil, sea ice, tundra, Atlantic Ocean, Great Dismal Swamp, Kuwait oil fire smoke. Recent upgrades to instrument (new TOMS UVA channels at 340 and 380 planned use in Africa (SAFARI 2000) and possibly for MEIDEX will also be discussed. This talk also plans to discuss the spectral variation of surface reflectance over land and the sensitivity of off-nadir view angles to correlation between visible near-infrared reflectance for use in remote sensing of aerosol over land.

  15. Aerosol behaviour modeling and measurements

    International Nuclear Information System (INIS)

    Gieseke, J.A.; Reed, L.D.

    1977-01-01

    Aerosol behavior within Liquid Metal Fast Breeder Reactor (LMFBR) containments is of critical importance since most of the radioactive species are expected to be associated with particulate forms and the mass of radiologically significant material leaked to the ambient atmosphere is directly related to the aerosol concentration airborne within the containment. Mathematical models describing the behavior of aerosols in closed environments, besides providing a direct means of assessing the importance of specific assumptions regarding accident sequences, will also serve as the basic tool with which to predict the consequences of various postulated accident situations. Consequently, considerable efforts have been recently directed toward the development of accurate and physically realistic theoretical aerosol behavior models. These models have accounted for various mechanisms affecting agglomeration rates of airborne particulate matter as well as particle removal rates from closed systems. In all cases, spatial variations within containments have been neglected and a well-mixed control volume has been assumed. Examples of existing computer codes formulated from the mathematical aerosol behavior models are the Brookhaven National Laboratory TRAP code, the PARDISEKO-II and PARDISEKO-III codes developed at Karlsruhe Nuclear Research Center, and the HAA-2, HAA-3, and HAA-3B codes developed by Atomics International. Because of their attractive short computation times, the HAA-3 and HAA-3B codes have been used extensively for safety analyses and are attractive candidates with which to demonstrate order of magnitude estimates of the effects of various physical assumptions. Therefore, the HAA-3B code was used as the nucleus upon which changes have been made to account for various physical mechanisms which are expected to be present in postulated accident situations and the latest of the resulting codes has been termed the HAARM-2 code. It is the primary purpose of the HAARM

  16. Characteristics of the surface source of radioactive atmospheric aerosols in the 30km Chernobyl zone

    International Nuclear Information System (INIS)

    Garger, E.; Gurgula, B.; Kashpur, V.; Kostezh, A.

    1993-01-01

    Territory contaminated by radionuclides around Chernobyl Nuclear Power Plant is the surface source of radioactive atmospheric aerosols due to the natural wind resuspension and ''technogenic'' activity. The present work is devoted to characterizing this source. Measurements of the spacial distribution of soil contamination, atmospheric dry deposition, volume concentration of radioactive aerosols and their variability in space and time, distribution of the radioactivity according to the size of aerosol particles, and size distribution of ''hot'' particles in the surface layer of the atmosphere were taken and the power of the surface source of the radioactivity aerosol was estimated. (author)

  17. An algorithm for hyperspectral remote sensing of aerosols: 2. Information content analysis for aerosol parameters and principal components of surface spectra

    Science.gov (United States)

    Hou, Weizhen; Wang, Jun; Xu, Xiaoguang; Reid, Jeffrey S.

    2017-05-01

    This paper describes the second part of a series of investigation to develop algorithms for simultaneous retrieval of aerosol parameters and surface reflectance from the future hyperspectral and geostationary satellite sensors such as Tropospheric Emissions: Monitoring of POllution (TEMPO). The information content in these hyperspectral measurements is analyzed for 6 principal components (PCs) of surface spectra and a total of 14 aerosol parameters that describe the columnar aerosol volume Vtotal, fine-mode aerosol volume fraction, and the size distribution and wavelength-dependent index of refraction in both coarse and fine mode aerosols. Forward simulations of atmospheric radiative transfer are conducted for 5 surface types (green vegetation, bare soil, rangeland, concrete and mixed surface case) and a wide range of aerosol mixtures. It is shown that the PCs of surface spectra in the atmospheric window channel could be derived from the top-of-the-atmosphere reflectance in the conditions of low aerosol optical depth (AOD ≤ 0.2 at 550 nm), with a relative error of 1%. With degree freedom for signal analysis and the sequential forward selection method, the common bands for different aerosol mixture types and surface types can be selected for aerosol retrieval. The first 20% of our selected bands accounts for more than 90% of information content for aerosols, and only 4 PCs are needed to reconstruct surface reflectance. However, the information content in these common bands from each TEMPO individual observation is insufficient for the simultaneous retrieval of surface's PC weight coefficients and multiple aerosol parameters (other than Vtotal). In contrast, with multiple observations for the same location from TEMPO in multiple consecutive days, 1-3 additional aerosol parameters could be retrieved. Consequently, a self-adjustable aerosol retrieval algorithm to account for surface types, AOD conditions, and multiple-consecutive observations is recommended to derive

  18. Measurements with self-identifying aerosols

    International Nuclear Information System (INIS)

    Kyle, T.; Schuster, B.G.

    1978-01-01

    The use of modern single particle detection of aerosols has made it possible to test multiple HEPA filter systems. Problems have been encountered in such tests with the background aerosol on the downstream side of the filters. Since the ducts are maintained at a negative pressure, ambient aerosols leak into the ducts and provide concentrations of particles which are comparable to the number of particles of the test aerosol passing through the filters. The background count creates an upper limit to the protection factor which can be measured. This limitation can be overcome by the use of an identifiable aerosol. The most direct method of identifying an aerosol is to use fluorescent particles, which has been done in the past. In the present case, the fluorescence of the individual particle is used, rather than dissolving the particles in solution to develop the fluorescence. Two systems based upon fluorescent solid or liquid particles are being developed. Both involve single particle detection and excitation by a portable helium-cadmium laser. The advantage of the solid particles system is the ability to capture the particles on a filter. The filter can then be dissolved and the number of particles counted and sized, since the particles do not dissolve. This also permits the use of greater sample flow rates than is possible with a real time system

  19. Surface Layer Turbulence and Aerosol Profiles During MAPTIP

    NARCIS (Netherlands)

    Davidson, K.L.; Frederickson, P.A.; Leeuw, G. de

    1995-01-01

    The Naval Postgraduate School (NPS) and the TNO Physics and Electronics Laboratory (TNO-FEL) deployed in situ sensors near and on Meetpost Noordwijk (MPN) during MAPTIP to describe the surface layer processes and also to evaluate models for near-surface aerosol profiles. Vertical profiles of aerosol

  20. Surface Chemistry at Size-Selected Nano-Aerosol Particles

    Science.gov (United States)

    Roberts, Jeffrey

    2005-03-01

    A method has been developed to conduct surface chemistry and extract surface kinetic rates from size-selected aerosol nanoparticles. The measurements encompass broad ranges of particle size, phase, and composition. Results will be presented on the uptake of water by aerosolized soot nanoparticles of radius between 10 and 40 nm. Water uptake was monitored by tandem differential mobility analysis (T-DMA), which is capable of measuring changes in particle diameter as little as 0.2 nm. Soot particles were produced in an ethene diffusion flame and extracted into an atmospheric pressure aerosol flow tube reactor. The particles were subjected to various thermal and oxidative treatments, and the effects of these treatments on the ability of soot to adsorb monolayer quantities of water was determined. The results are important because soot nucleates atmospheric cloud particles. More generally, the results represent one of the first kinetic and mechanistic studies of gas-phase nanoparticle reactivity. Co-author: Henry Ajo, University of Minnesota

  1. Size Resolved Measurements of Springtime Aerosol Particles over the Northern South China Sea

    Science.gov (United States)

    Atwood, Samuel A.; Reid, Jeffrey S.; Kreidenweis, Sonia M.; Cliff, Stephen S.; Zhao, Yongjing; Lin, Neng-Huei; Tsay, Si-Chee; Chu, Yu-Chi; Westphal, Douglas L.

    2012-01-01

    Large sources of aerosol particles and their precursors are ubiquitous in East Asia. Such sources are known to impact the South China Sea (henceforth SCS), a sometimes heavily polluted region that has been suggested as particularly vulnerable to climate change. To help elucidate springtime aerosol transport into the SCS, an intensive study was performed on the remote Dongsha (aka Pratas) Islands Atoll in spring 2010. As part of this deployment, a Davis Rotating-drum Uniform size-cut Monitor (DRUM) cascade impactor was deployed to collect size-resolved aerosol samples at the surface that were analyzed by X-ray fluorescence for concentrations of selected elements. HYSPLIT backtrajectories indicated that the transport of aerosol observed at the surface at Dongsha was occurring primarily from regions generally to the north and east. This observation was consistent with the apparent persistence of pollution and dust aerosol, along with sea salt, in the ground-based dataset. In contrast to the sea-level observations, modeled aerosol transport suggested that the westerly flow aloft (w700 hPa) transported smoke-laden air toward the site from regions from the south and west. Measured aerosol optical depth at the site was highest during time periods of modeled heavy smoke loadings aloft. These periods did not coincide with elevated aerosol concentrations at the surface, although the model suggested sporadic mixing of this free-tropospheric aerosol to the surface over the SCS. A biomass burning signature was not clearly identified in the surface aerosol composition data, consistent with this aerosol type remaining primarily aloft and not mixing strongly to the surface during the study. Significant vertical wind shear in the region also supports the idea that different source regions lead to varying aerosol impacts in different vertical layers, and suggests the potential for considerable vertical inhomogeneity in the SCS aerosol environment.

  2. Aerosol measurements and nuclear accidents: a reconsideration

    International Nuclear Information System (INIS)

    Raes, F.

    1988-01-01

    Within its radioactivity environmental monitoring programme, the Commission of the European Communities and in particular its Joint Research Centre wants to encourage the qualitative improvement of radioactivity monitoring. On 3 and 4 December 1987 an experts' meeting has been organized by the Ispra Joint Research Centre in collaboration with the Gesellschaft fuer Aerosolforschung, in order to discuss measuring techniques for radioactive aerosols in the environment in case of a nuclear accident. During the workshop, current practices in routine monitoring programmes in the near and far field of nuclear power plants were confronted with the latest developments in the metrology of aerosols and radioactivity. The need and feasibility of implementing advanced aerosol and radioactivity techniques in routine monitoring networks have been discussed. This publication gives the full text of 12 presentations and a report of the roundtable discussion being held afterwards. It does not intend to give a complete picture of all activities going on in the field of radioactive aerosol metrology; it rather collects a number of common statements of people who approach the problem from quite different directions

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

    Science.gov (United States)

    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.

  4. Coherent Uncertainty Analysis of Aerosol Measurements from Multiple Satellite Sensors

    Science.gov (United States)

    Petrenko, M.; Ichoku, C.

    2013-01-01

    Aerosol retrievals from multiple spaceborne sensors, including MODIS (on Terra and Aqua), MISR, OMI, POLDER, CALIOP, and SeaWiFS altogether, a total of 11 different aerosol products were comparatively analyzed using data collocated with ground-based aerosol observations from the Aerosol Robotic Network (AERONET) stations within the Multi-sensor Aerosol Products Sampling System (MAPSS, http://giovanni.gsfc.nasa.gov/mapss/ and http://giovanni.gsfc.nasa.gov/aerostat/). The analysis was performed by comparing quality-screened satellite aerosol optical depth or thickness (AOD or AOT) retrievals during 2006-2010 to available collocated AERONET measurements globally, regionally, and seasonally, and deriving a number of statistical measures of accuracy. We used a robust statistical approach to detect and remove possible outliers in the collocated data that can bias the results of the analysis. Overall, the proportion of outliers in each of the quality-screened AOD products was within 12%. Squared correlation coefficient (R2) values of the satellite AOD retrievals relative to AERONET exceeded 0.6, with R2 for most of the products exceeding 0.7 over land and 0.8 over ocean. Root mean square error (RMSE) values for most of the AOD products were within 0.15 over land and 0.09 over ocean. We have been able to generate global maps showing regions where the different products present advantages over the others, as well as the relative performance of each product over different landcover types. It was observed that while MODIS, MISR, and SeaWiFS provide accurate retrievals over most of the landcover types, multi-angle capabilities make MISR the only sensor to retrieve reliable AOD over barren and snow / ice surfaces. Likewise, active sensing enables CALIOP to retrieve aerosol properties over bright-surface shrublands more accurately than the other sensors, while POLDER, which is the only one of the sensors capable of measuring polarized aerosols, outperforms other sensors in

  5. Coherent uncertainty analysis of aerosol measurements from multiple satellite sensors

    Directory of Open Access Journals (Sweden)

    M. Petrenko

    2013-07-01

    Full Text Available Aerosol retrievals from multiple spaceborne sensors, including MODIS (on Terra and Aqua, MISR, OMI, POLDER, CALIOP, and SeaWiFS – altogether, a total of 11 different aerosol products – were comparatively analyzed using data collocated with ground-based aerosol observations from the Aerosol Robotic Network (AERONET stations within the Multi-sensor Aerosol Products Sampling System (MAPSS, http://giovanni.gsfc.nasa.gov/mapss/ and http://giovanni.gsfc.nasa.gov/aerostat/. The analysis was performed by comparing quality-screened satellite aerosol optical depth or thickness (AOD or AOT retrievals during 2006–2010 to available collocated AERONET measurements globally, regionally, and seasonally, and deriving a number of statistical measures of accuracy. We used a robust statistical approach to detect and remove possible outliers in the collocated data that can bias the results of the analysis. Overall, the proportion of outliers in each of the quality-screened AOD products was within 7%. Squared correlation coefficient (R2 values of the satellite AOD retrievals relative to AERONET exceeded 0.8 for many of the analyzed products, while root mean square error (RMSE values for most of the AOD products were within 0.15 over land and 0.07 over ocean. We have been able to generate global maps showing regions where the different products present advantages over the others, as well as the relative performance of each product over different land cover types. It was observed that while MODIS, MISR, and SeaWiFS provide accurate retrievals over most of the land cover types, multi-angle capabilities make MISR the only sensor to retrieve reliable AOD over barren and snow/ice surfaces. Likewise, active sensing enables CALIOP to retrieve aerosol properties over bright-surface closed shrublands more accurately than the other sensors, while POLDER, which is the only one of the sensors capable of measuring polarized aerosols, outperforms other sensors in certain

  6. Reconciling satellite aerosol optical thickness and surface fine particle mass through aerosol liquid water: ALW AND AOT

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Thien Khoi V. [Department of Environmental Sciences, Rutgers University, New Brunswick New Jersey USA; Ghate, Virendra P. [Environmental Science Division, Argonne National Laboratory, Argonne Illinois USA; Carlton, Annmarie G. [Department of Chemistry, University of California, Irvine California USA

    2016-11-22

    Summertime aerosol optical thickness (AOT) over the Southeast U.S. is sharply enhanced over wintertime values. This seasonal pattern is unique and of particular interest because temperatures there have not warmed over the past 100 years. Patterns in surface fine particle mass are inconsistent with satellite reported AOT. In this work, we attempt to reconcile the spatial and temporal distribution of AOT over the U.S. with particle mass measurements at the surface by examining trends in aerosol liquid water (ALW), a particle constituent that scatters radiation affecting the satellite AOT, but is removed in mass measurements at routine surface monitoring sites. We employ the thermodynamic model ISORROPIAv2.1 to estimate ALW mass concentrations at IMRPOVE sites using measured ion mass concentrations and NARR meteorological data. Our findings suggest ALW provides a plausible explanation for the geographical and seasonal patterns in AOT and can reconcile previously noted discrepancies with surface mass measurements.

  7. Overview and preliminary results of the Surface Ocean Aerosol Production (SOAP campaign

    Directory of Open Access Journals (Sweden)

    C. S. Law

    2017-11-01

    Full Text Available Establishing the relationship between marine boundary layer (MBL aerosols and surface water biogeochemistry is required to understand aerosol and cloud production processes over the remote ocean and represent them more accurately in earth system models and global climate projections. This was addressed by the SOAP (Surface Ocean Aerosol Production campaign, which examined air–sea interaction over biologically productive frontal waters east of New Zealand. This overview details the objectives, regional context, sampling strategy and provisional findings of a pilot study, PreSOAP, in austral summer 2011 and the following SOAP voyage in late austral summer 2012. Both voyages characterized surface water and MBL composition in three phytoplankton blooms of differing species composition and biogeochemistry, with significant regional correlation observed between chlorophyll a and DMSsw. Surface seawater dimethylsulfide (DMSsw and associated air–sea DMS flux showed spatial variation during the SOAP voyage, with maxima of 25 nmol L−1 and 100 µmol m−2 d−1, respectively, recorded in a dinoflagellate bloom. Inclusion of SOAP data in a regional DMSsw compilation indicates that the current climatological mean is an underestimate for this region of the southwest Pacific. Estimation of the DMS gas transfer velocity (kDMS by independent techniques of eddy covariance and gradient flux showed good agreement, although both exhibited periodic deviations from model estimates. Flux anomalies were related to surface warming and sea surface microlayer enrichment and also reflected the heterogeneous distribution of DMSsw and the associated flux footprint. Other aerosol precursors measured included the halides and various volatile organic carbon compounds, with first measurements of the short-lived gases glyoxal and methylglyoxal in pristine Southern Ocean marine air indicating an unidentified local source. The application of a real-time clean sector

  8. Miniature Sensor for Aerosol Mass Measurements, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR project seeks to develop a miniature sensor for mass measurement of size-classified aerosols. A cascade impactor will be used to classify aerosol sample...

  9. Estimation of Aerosol Direct Radiative Effects from Satellite and In Situ Measurements

    Science.gov (United States)

    Bergstrom, Robert W.; Russell, Philip B.; Schmid, Beat; Redemann, Jens; McIntosh, Dawn

    2000-01-01

    Ames researchers have combined measurements from satellite, aircraft, and the surface to estimate the effect of airborne particles (aerosols) on the solar radiation over the North Atlantic region. These aerosols (which come from both natural and pollution sources) can reflect solar radiation, causing a cooling effect that opposes the warming caused by carbon dioxide. Recently, increased attention has been paid to aerosol effects to better understand the Earth climate system.

  10. Applications of Sunphotometry to Aerosol Extinction and Surface Anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Tsay, S.

    2002-09-30

    Support cost-sharing of a newly developed sunphotometer in field deployment for aerosol studies. This is a cost-sharing research to deploy a newly developed sun-sky-surface photometer for studying aerosol extinction and surface anisotropy at the ARM SGP, TWP, and NSA-AAO CART sites and in many field campaigns. Atmospheric aerosols affect the radiative energy balance of the Earth, both directly by perturbing the incoming/outgoing radiation fields and indirectly by influencing the properties/processes of clouds and reactive greenhouse gases. The surface bidirectional reflectance distribution function (BRDF) also plays a crucial role in the radiative energy balance, since the BRDF is required to determine (i) the spectral and spectrally-averaged surface albedo, and (ii) the top-of-the-atmosphere (TOA) angular distribution of radiance field. Therefore, the CART sites provide an excellent, albeit unique, opportunity to collect long-term climatic data in characterizing aerosol properties and various types of surface anisotropy.

  11. Chamber lidar measurements of biological aerosols.

    Science.gov (United States)

    Brown, David M; Thrush, Evan; Thomas, Michael E

    2011-02-10

    In order to determine the performance of standoff sensors against agents, there is a need to develop methods to characterize the optical properties of biological warfare agents. The goal of this work is to develop a methodology that would allow the characterization of agent optical cross sections from the UV to the longwave IR. The present work demonstrates an optical measurement architecture based on lidar technology, allowing the measurement of backscatter and depolarization ratio from biological aerosols (either simulants or agents) released in a refereed, 1m3 chamber. Measured results on simulant materials are calibrated and compared to theoretical simulations of the cross sections.

  12. Stackable differential mobility analyzer for aerosol measurement

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Meng-Dawn [Oak Ridge, TN; Chen, Da-Ren [Creve Coeur, MO

    2007-05-08

    A multi-stage differential mobility analyzer (MDMA) for aerosol measurements includes a first electrode or grid including at least one inlet or injection slit for receiving an aerosol including charged particles for analysis. A second electrode or grid is spaced apart from the first electrode. The second electrode has at least one sampling outlet disposed at a plurality different distances along its length. A volume between the first and the second electrode or grid between the inlet or injection slit and a distal one of the plurality of sampling outlets forms a classifying region, the first and second electrodes for charging to suitable potentials to create an electric field within the classifying region. At least one inlet or injection slit in the second electrode receives a sheath gas flow into an upstream end of the classifying region, wherein each sampling outlet functions as an independent DMA stage and classifies different size ranges of charged particles based on electric mobility simultaneously.

  13. Determination of atmospheric aerosol properties over land using satellite measurements

    NARCIS (Netherlands)

    Kokhanovsky, A.A.; Leeuw, G. de

    2009-01-01

    Mostly, aerosol properties are poorly understood because the aerosol properties are very sparse. The first workshop on the determination of atmospheric aerosol properties over land using satellite measurements is convened in Bremen, Germany. In this workshop, the topics of discussions included a

  14. Raman Lidar Measurements of Aerosol Extinction and Backscattering. Report 1; Methods and Comparisons

    Science.gov (United States)

    Ferrare, R. A.; Melfi, S. H.; Whiteman, D. N.; Evans, K. D.; Leifer, R.

    1998-01-01

    This paper examines the aerosol backscattering and extinction profiles measured at night by the NASA Goddard Space Flight Center Scanning Raman Lidar (SRL) during the remote cloud sensing (RCS) intensive operations period (IOP) at the Department of Energy Atmospheric Radiation Measurement (ARM) southern Great Plains (SGP) site in April 1994. These lidar data are used to derive aerosol profiles for altitudes between 0.0 1 5 and 5 km. Since this lidar detects Raman scattering from nitrogen and oxygen molecules as well as the elastic scattering from molecules and aerosols, it measures both aerosol backscattering and extinction simultaneously. The aerosol extinction/backscattering ratio varied between approximately 30 sr and 75 sr at 351 nm. Aerosol optical thicknesses derived by integrating the lidar profiles of aerosol extinction measured at night between 0. I and 5 km are found to be about 10-40% lower than those measured by a Sun photometer during the day. This difference is attributed to the contribution by stratospheric aerosols not included in the lidar estimates as well as to diurnal differences in aerosol properties and concentrations. Aerosol profiles close to the surface were acquired by pointing the lidar nearly horizontally. Measurements of aerosol scattering from a tower-mounted nephelometer are found to be 40% lower than lidar measurements of aerosol extinction over a wide range of relative humidities even after accounting for the difference in wavelengths. The reasons for this difference are not clear but may be due to the inability of the nephelometer to accurately measure scattering by large particles.

  15. Retrieve Aerosol Concentration Based On Surface Model and Distribution of Concentration of PM2.5

    Science.gov (United States)

    Cui, Hongzhi

    2017-04-01

    As China's economy continues to grow, urbanization continues to advance, along with growth in all areas to pollutant emissions in the air industry, air quality also continued to deteriorate. Aerosol concentrations as a measure of air quality of the most important part of are more and more people's attention. Traditional monitoring stations measuring aerosol concentration method is accurate, but time-consuming and can't be done simultaneously measure a large area, can only rely on data from several monitoring sites to predict the concentration of the panorama. Remote Sensing Technology retrieves aerosol concentrations being by virtue of their efficient, fast advantages gradually into sight. In this paper, by the method of surface model to start with the physical processes of atmospheric transport, innovative aerosol concentration coefficient proposed to replace the traditional aerosol concentrations, pushed to a set of retrieval of aerosol concentration coefficient method, enabling fast and efficient Get accurate air pollution target area. At the same paper also monitoring data for PM2.5 in Beijing were analyzed from different angles, from the perspective of the data summarized in Beijing PM2.5 concentration of time, space, geographical distribution and concentration of PM2.5 and explored the relationship between aerosol concentration coefficient and concentration of PM2.5. Key words,Air Pollution, Aerosol concentration , PM2.5 , Retrieve

  16. Adsorption and revaporisation studies on iodine oxide aerosols deposited on containment surface materials in LWR

    Energy Technology Data Exchange (ETDEWEB)

    Tietze, S.; Foreman, M.R.StJ.; Ekberg, C. [Chalmers Univ. of Technology, Goeteborg (Sweden); Kaerkelae, T.; Auvinen, A.; Tapper, U.; Lamminmaeki, S.; Jokiniemi, J. [VTT Technical Research Centre of Finland, Espoo (Finland)

    2012-12-15

    During a hypothetical severe nuclear accident, the radiation field will be very high in the nuclear reactor containment building. As a result gaseous radiolysis products will be formed. Elemental iodine can react in the gaseous phase with ozone to form solid iodine oxide aerosol particles (iodine oxide). Within the AIAS (Adsorption of Iodine oxide Aerosols on Surfaces) project the interactions of iodine oxide (IOx) aerosols with common containment surface materials were investigated. Common surface materials in Swedish and Finnish LWRs are Teknopox Aqua V A paint films and metal surfaces such as Cu, Zn, Al and SS, as well as Pt and Pd surfaces from hydrogen recombiners. Non-radioactive and {sup 131}I labelled iodine oxide aerosols were produced with the EXSI CONT facility from elemental iodine and ozone at VTT Technical Research Centre of Finland. The iodine oxide deposits were analysed with microscopic and spectroscopic measurement techniques to identify the kind of iodine oxide formed and if a chemical conversion on the different surface materials occurs. The revaporisation behaviour of the deposited iodine oxide aerosol particles from the different surface materials was studied under the influence of heat, humidity and gamma irradiation at Chalmers University of Technology, Sweden. Studies on the effects of humidity were performed using the FOMICAG facility, while heat and irradiation experiments were performed in a thermostated heating block and with a gammacell 22 having a dose rate of 14 kGy/h. The revaporisation losses were measured using a HPGe detector. The revaporisated {sup 131}I species from the surfaces were chemically tested for elemental iodine formation. The parameter dominating the degradation of the produced iodine oxide aerosols was humidity. Cu and Zn surfaces were found to react with iodine from the iodine oxide aerosols to form iodides, while no metal iodides were detected for Al and SS samples. Most of the iodine oxide aerosols are assumed to

  17. Simulation study of the aerosol information content in OMI spectral reflectance measurements

    Directory of Open Access Journals (Sweden)

    B. Veihelmann

    2007-06-01

    Full Text Available The Ozone Monitoring Instrument (OMI is an imaging UV-VIS solar backscatter spectrometer and is designed and used primarily to retrieve trace gases like O3 and NO2 from the measured Earth reflectance spectrum in the UV-visible (270–500 nm. However, also aerosols are an important science target of OMI. The multi-wavelength algorithm is used to retrieve aerosol parameters from OMI spectral reflectance measurements in up to 20 wavelength bands. A Principal Component Analysis (PCA is performed to quantify the information content of OMI reflectance measurements on aerosols and to assess the capability of the multi-wavelength algorithm to discern various aerosol types. This analysis is applied to synthetic reflectance measurements for desert dust, biomass burning aerosols, and weakly absorbing anthropogenic aerosol with a variety of aerosol optical thicknesses, aerosol layer altitudes, refractive indices and size distributions. The range of aerosol parameters considered covers the natural variability of tropospheric aerosols. This theoretical analysis is performed for a large number of scenarios with various geometries and surface albedo spectra for ocean, soil and vegetation. When the surface albedo spectrum is accurately known and clouds are absent, OMI reflectance measurements have 2 to 4 degrees of freedom that can be attributed to aerosol parameters. This information content depends on the observation geometry and the surface albedo spectrum. An additional wavelength band is evaluated, that comprises the O2-O2 absorption band at a wavelength of 477 nm. It is found that this wavelength band adds significantly more information than any other individual band.

  18. Understanding the aerosol information content in multi-spectral reflectance measurements using a synergetic retrieval algorithm

    Directory of Open Access Journals (Sweden)

    D. Martynenko

    2010-11-01

    Full Text Available An information content analysis for multi-wavelength SYNergetic AErosol Retrieval algorithm SYNAER was performed to quantify the number of independent pieces of information that can be retrieved. In particular, the capability of SYNAER to discern various aerosol types is assessed. This information content depends on the aerosol optical depth, the surface albedo spectrum and the observation geometry. The theoretical analysis is performed for a large number of scenarios with various geometries and surface albedo spectra for ocean, soil and vegetation. When the surface albedo spectrum and its accuracy is known under cloud-free conditions, reflectance measurements used in SYNAER is able to provide for 2–4° of freedom that can be attributed to retrieval parameters: aerosol optical depth, aerosol type and surface albedo.

    The focus of this work is placed on an information content analysis with emphasis to the aerosol type classification. This analysis is applied to synthetic reflectance measurements for 40 predefined aerosol mixtures of different basic components, given by sea salt, mineral dust, biomass burning and diesel aerosols, water soluble and water insoluble aerosols. The range of aerosol parameters considered through the 40 mixtures covers the natural variability of tropospheric aerosols. After the information content analysis performed in Holzer-Popp et al. (2008 there was a necessity to compare derived degrees of freedom with retrieved aerosol optical depth for different aerosol types, which is the main focus of this paper.

    The principle component analysis was used to determine the correspondence between degrees of freedom for signal in the retrieval and derived aerosol types. The main results of the analysis indicate correspondence between the major groups of the aerosol types, which are: water soluble aerosol, soot, mineral dust and sea salt and degrees of freedom in the algorithm and show the ability of the SYNAER to

  19. Airborne High Spectral Resolution Lidar Aerosol Measurements during MILAGRO and TEXAQS/GOMACCS

    Science.gov (United States)

    Ferrare, Richard; Hostetler, Chris; Hair, John; Cook Anthony; Harper, David; Burton, Sharon; Clayton, Marian; Clarke, Antony; Russell, Phil; Redemann, Jens

    2007-01-01

    Two1 field experiments conducted during 2006 provided opportunities to investigate the variability of aerosol properties near cities and the impacts of these aerosols on air quality and radiative transfer. The Megacity Initiative: Local and Global Research Observations (MILAGRO) /Megacity Aerosol Experiment in Mexico City (MAX-MEX)/Intercontinental Chemical Transport Experiment-B (INTEX-B) joint experiment conducted during March 2006 investigated the evolution and transport of pollution from Mexico City. The Texas Air Quality Study (TEXAQS)/Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) (http://www.al.noaa.gov/2006/) conducted during August and September 2006 investigated climate and air quality in the Houston/Gulf of Mexico region. During both missions, the new NASA Langley airborne High Spectral Resolution Lidar (HSRL) was deployed on the NASA Langley B200 King Air aircraft and measured profiles of aerosol extinction, backscattering, and depolarization to: 1) characterize the spatial and vertical distributions of aerosols, 2) quantify aerosol extinction and optical thickness contributed by various aerosol types, 3) investigate aerosol variability near clouds, 4) evaluate model simulations of aerosol transport, and 5) assess aerosol optical properties derived from a combination of surface, airborne, and satellite measurements.

  20. Phenomenological study of aerosol dry deposition in urban area: surface properties, turbulence and local meteorology influences

    International Nuclear Information System (INIS)

    Roupsard, P.

    2013-01-01

    Aerosol dry deposition is not much known for urban areas due to the lack of data. Knowledge on this phenomenon is necessary to understand pollutant fluxes in cities and to estimate inhabitant exposition to ionizing radiation of radioactive aerosols. A data providing could enable to enhance dry deposition models for these areas. An original experimental approach is performed to study submicron aerosol dry deposition on urban surfaces. Wind tunnel coupled to in situ experiments give results to study different physical phenomenon governing dry deposition. Dry deposition velocities are measured using aerosol tracers. These data are associated to turbulent and meteorological measured conditions. This database permits to classify the principal physical phenomenon for each experiment type. Finally, different phenomenon must be considered for chronic and acute exposition of urban surfaces to atmospheric particles. (author)

  1. Measurements of dynamic shape factors of LMFBR aggregate aerosols

    International Nuclear Information System (INIS)

    Allen, M.D.; Moss, O.R.; Briant, J.K.

    1980-01-01

    Dynamic shape factors for branched, chain-like aggregates of LMFBR mixed-oxide fuels have been measured with a LAPS spiral-duct centrifuge. The aerosol was generated by repeatedly pulsing a focused laser beam onto the surface of a typical LMFBR fuel pellet. The measured values of the dynamic shape factor, corrected for slip, vary between kappa = 3.60 at D/sub ae/ = 0.5 μm, and kappa = 2.23 at D/sub ae/ = 1.5 μm

  2. Global Aerosol Effect Retrieval From Passive Hyperspectral Measurements

    Science.gov (United States)

    de Graaf, M.; Tilstra, L. G.; Stammes, P.

    2013-12-01

    Absorbing aerosols can have a significant local direct radiative effect (DRE), while the global average aerosol DRE remains highly uncertain. Modelling studies have shown that the magnitude and sign of the aerosol DRE at the top of the atmosphere (TOA) depend on the scene, especially on the albedo of the scene under the aerosol layer. It changes with cloud fraction, from large positive for overcast conditions when aerosols are present above the cloud, to large negative for clear sky ocean scenes. Observational studies, which are necessary to constrain the model studies, have been scarce. The results of modelling studies depend strongly on the assumed aerosol properties. Observational studies also need to assume aerosol type and geophysical properties to derive aerosol optical properties from radiation measurements. This introduces large uncertainties in the retrieved aerosol DRE. Furthermore, the retrieval of aerosols over clouds from passive instruments is difficult, due to the large optical thickness of clouds. Therefore, observational studies of aerosol direct and indirect effects from passive satellite instruments are invariably restricted to aerosol studies close to the cloud edges. We have developed a method to derive the aerosol DRE for smoke over clouds directly from passive satellite hyperspectral reflectance measurements, independent of aerosol micro- physical property assumptions. This allows us to assess the local aerosol DRE from passive imagery directly on a pixel to pixel basis, even over clouds. The solar radiative absorption by smoke layers is quantified using the TOA reflectance spectrum from the ultraviolet (UV) to the shortwave infrared (SWIR). UV- absorbing aerosols have a strong signature that can be detected using UV reflectance measurements. Since the aerosol extinction optical thickness decreases rapidly with increasing wavelength for smoke, the properties of the scene below the aerosol layer can be retrieved in the SWIR, where aerosol

  3. Satellite Detection of Smoke Aerosols Over a Snow/Ice Surface by TOMS

    Science.gov (United States)

    Hsu, N. Christina; Herman, Jay R.; Gleason, J. F.; Torres, O.; Seftor, C. J.

    1998-01-01

    The use of TOMS (Total Ozone Mapping Spectrometer) satellite data demonstrates the recently developed technique of using satellite UV radiance measurements to detect absorbing tropospheric aerosols is effective over snow/ice surfaces. Instead of the traditional single wavelength (visible or infrared) method of measuring tropospheric aerosols, this method takes advantage of the wavelength dependent reduction in the backscattered radiance due to the presence of absorbing aerosols over snow/ice surfaces. An example of the resulting aerosol distribution derived from TOMS data is shown for an August 1998 event in which smoke generated by Canadian forest fires drifts over and across Greenland. As the smoke plume moved over Greenland, the TOMS observed 380 nm reflectivity over the snow/ice surface dropped drastically from 90-100% down to 30-40%. To study the effects of this smoke plume in both the UV and visible regions of the spectrum, we compared a smoke-laden spectrum taken over Greenland by the high spectral resolution (300 to 800 nm) GOME instrument with one that is aerosol-free. We also discuss the results of modeling the darkening effects of various types of absorbing aerosols over snow/ice surfaces using a radiative transfer code. Finally, we investigated the history of such events by looking at the nearly twenty year record of TOMS aerosol index measurements and found that there is a large interannual variability in the amount of smoke aerosols observed over Greenland. This information will be available for studies of radiation and transport properties in the Arctic.

  4. Micrometeorological flux measurements of aerosol and gases above Beijing

    Science.gov (United States)

    Nemitz, Eiko; Langford, Ben; Mullinger, Neil; Cowan, Nicholas; Coyle, Mhairi; Acton, William Joe; Lee, James; Fu, Pingqing

    2017-04-01

    Air pollution is estimated to cause 1.6 million premature deaths in China every year and in the winter 2016/17 Beijing had to issue health alerts and put in place ad hoc limitations on industrial and vehicular activity. Much of this pollution is attributed to emissions from industrial processes and in particular coal combustion. By contrast, the diffuse pollutant sources within the city are less well understood. This includes, e.g., emissions from the Beijing traffic fleet, the sewage system, food preparation, solid fuel combustion in the streets and small industrial processes. Within the framework of a major UK-Chinese collaboration to study air pollution and its impact on human health in Beijing, we therefore measured fluxes of a large range of pollutants from a height of 102 m on the 325 m meteorological tower at the Institute of Atmospheric Physics. Several instruments were mounted at 102 m: fluxes of CO2 and H2O were measured with an infrared gas analyser (LiCOR 7500) and fluxes of ozone with a combination of a relative fast-response ozone analyser (ROFI) and a 2B absolute O3 instrument. Total particle number fluxes were measured with a condensation particle counter (TSI CPC 3785), and size-segregated fluxes over the size range 0.06 to 20 μm with a combination of an optical Ultrafine High Sensitivity Aerosol Spectrometer (UHSAS) and an Aerodynamic Particle Sizer Spectrometer (TSI APS3321). Ammonia (NH3) fluxes were measured for the first time above the urban environment using an Aerodyne compact quantum cascade laser (QCL). In addition, composition resolved aerosol fluxes were measured with an Aerodyne Aerosol Mass Spectrometer (HR-ToF-AMS), operated in a measurement container at the bottom of the tower, which subsampled from a 120 m long copper tube (15 mm OD). The analysis so far suggests that, due to often low wind speeds, fluxes were at times de-coupled from the surface. Fluxes normalised by CO2, a tracer for the amount of fossil fuel consumed, should be

  5. Estimating the maritime component of aerosol optical depth and its dependency on surface wind speed using satellite data

    Directory of Open Access Journals (Sweden)

    Y. Lehahn

    2010-07-01

    Full Text Available Six years (2003–2008 of satellite measurements of aerosol parameters from the Moderate Resolution Imaging Spectroradiometer (MODIS and surface wind speeds from Quick Scatterometer (QuikSCAT, the Advanced Microwave Scanning Radiometer (AMSR-E, and the Special Sensor Microwave Imager (SSM/I, are used to provide a comprehensive perspective on the link between surface wind speed and marine aerosol optical depth over tropical and subtropical oceanic regions. A systematic comparison between the satellite derived fields in these regions allows to: (i separate the relative contribution of wind-induced marine aerosol to the aerosol optical depth; (ii extract an empirical linear equation linking coarse marine aerosol optical depth and wind intensity; and (iii identify a time scale for correlating marine aerosol optical depth and surface wind speed. The contribution of wind induced marine aerosol to aerosol optical depth is found to be dominated by the coarse mode elements. When wind intensity exceeds 4 m/s, coarse marine aerosol optical depth is linearly correlated with the surface wind speed, with a remarkably consistent slope of 0.009±0.002 s/m. A detailed time scale analysis shows that the linear correlation between the fields is well kept within a 12 h time frame, while sharply decreasing when the time lag between measurements is longer. The background aerosol optical depth, associated with aerosols that are not produced in-situ through wind driven processes, can be used for estimating the contributions of terrestrial and biogenic marine aerosol to over-ocean satellite retrievals of aerosol optical depth.

  6. Measurement of the deposition of aerosol particles to skin, hair and clothing

    International Nuclear Information System (INIS)

    Bell, K.F.

    1999-01-01

    In the event of a nuclear accident, there are several routes whereby human populations may receive a radioactive dose from material released to the environment. The dose from radioactive aerosol deposited onto the surfaces of the human body has previously been estimated by assuming that aerosol deposition velocities (defined as the flux of aerosol onto a surface divided by the aerosol concentration above the surface) onto human body surfaces are similar to the values for inanimate surfaces. However, Jones (1990) modelled the effects on health of fallout material deposited on skin and clothing and found that the number of early deaths from skin dose was sensitively dependent on aerosol deposition velocity. He also pointed out that there was a lack of experimentally derived data on aerosol deposition velocities to human body surfaces and that the above mentioned assumption may not be valid. The purpose of the present work is to measure aerosol deposition velocities onto human body surfaces, the resultant data to allow more accurate nuclear accident consequence modelling. Aerosol deposition velocities onto human body surfaces in simulated indoor conditions have been measured by releasing tracer aerosols of three mean particle diameters (2.6, 6.2 and 9.2μm) into a test chamber containing volunteers. The skin, hair and clothing of the volunteers were sampled and analysed for deposited aerosol by Neutron Activation Analysis. Aerosol deposition velocities onto skin in the range 1.3 - 15 x 10 -3 ms -1 were recorded, values which are approximately an order of magnitude higher than the equivalent values onto the floor of the test room. These values suggest that the exposure route of radioactive aerosol particles deposited on the skin may be more significant than hitherto had been assumed. The possible mechanisms leading to this relatively high deposition were investigated experimentally and the results suggested that a combination of factors such as the body's electrostatic

  7. Size distribution measurements and chemical analysis of aerosol components

    Energy Technology Data Exchange (ETDEWEB)

    Pakkanen, T.A.

    1995-12-31

    with atmospheric sea salt particles. The chloride loss was found to decrease with increasing particle size suggesting that surface reaction mechanisms were important. Overall, the results obtained in this work describe the present methods used in all steps of accurate size distribution measurements of aerosol components and demonstrate the usefulness and possibilities of size distribution measurements in various scientific studies. (orig.)

  8. A characterization of Arctic aerosols on the basis of aerosol optical depth and black carbon measurements

    Directory of Open Access Journals (Sweden)

    R. S. Stone

    2014-06-01

    Full Text Available Abstract Aerosols, transported from distant source regions, influence the Arctic surface radiation budget. When deposited on snow and ice, carbonaceous particles can reduce the surface albedo, which accelerates melting, leading to a temperature-albedo feedback that amplifies Arctic warming. Black carbon (BC, in particular, has been implicated as a major warming agent at high latitudes. BC and co-emitted aerosols in the atmosphere, however, attenuate sunlight and radiatively cool the surface. Warming by soot deposition and cooling by atmospheric aerosols are referred to as “darkening” and “dimming” effects, respectively. In this study, climatologies of spectral aerosol optical depth AOD (2001–2011 and Equivalent BC (EBC (1989–2011 from three Arctic observatories and from a number of aircraft campaigns are used to characterize Arctic aerosols. Since the 1980s, concentrations of BC in the Arctic have decreased by more than 50% at ground stations where in situ observations are made. AOD has increased slightly during the past decade, with variations attributed to changing emission inventories and source strengths of natural aerosols, including biomass smoke and volcanic aerosol, further influenced by deposition rates and airflow patterns.

  9. Aerosol Classification from High Spectral Resolution Lidar Measurements

    Science.gov (United States)

    Burton, S. P.; Hair, J. W.; Ferrare, R. A.; Hostetler, C. A.; Kahnert, M.; Vaughan, M. A.; Cook, A. L.; Harper, D. B.; Berkoff, T.; Seaman, S. T.; Collins, J. E., Jr.; Fenn, M. A.; Rogers, R. R.

    2015-12-01

    The NASA Langley airborne High Spectral Resolution Lidars, HSRL-1 and HSRL-2, have acquired large datasets of vertically resolved aerosol extinction, backscatter, and depolarization during >30 airborne field missions since 2006. The lidar measurements of aerosol intensive parameters like lidar ratio and color ratio embed information about intrinsic aerosol properties, and are combined to qualitatively classify HSRL aerosol measurements into aerosol types. Knowledge of aerosol type is important for assessing aerosol radiative forcing, and can provide useful information for source attribution studies. However, atmospheric aerosol is frequently not a single pure type, but instead is a mixture, which affects the optical and radiative properties of the aerosol. We show that aerosol intensive parameters measured by lidar can be understood using mixing rules for cases of external mixing. Beyond coarse classification and mixing between classes, variations in the lidar aerosol intensive parameters provide additional insight into aerosol processes and composition. This is illustrated by depolarization measurements at three wavelengths, 355 nm, 532 nm, and 1064 nm, made by HSRL-2. Particle depolarization ratio is an indicator of non-spherical particles. Three cases each have a significantly different spectral dependence of the depolarization ratio, related to the size of the depolarizing particles. For two dust cases, large non-spherical particles account for the depolarization of the lidar light. The spectral dependence reflects the size distribution of these particles and reveals differences in the transport histories of the two plumes. For a smoke case, the depolarization is inferred to be due to the presence of small coated soot aggregates. Interestingly, the depolarization at 355 nm is similar for this smoke case compared to the dust cases, having potential implications for the upcoming EarthCARE satellite, which will measure particle depolarization ratio only at 355 nm.

  10. Chemically-resolved aerosol eddy covariance flux measurements in urban Mexico City during MILAGRO 2006

    Science.gov (United States)

    Zalakeviciute, R.; Alexander, M. L.; Allwine, E.; Jimenez, J. L.; Jobson, B. T.; Molina, L. T.; Nemitz, E.; Pressley, S. N.; VanReken, T. M.; Ulbrich, I. M.; Velasco, E.; Lamb, B. K.

    2012-08-01

    As part of the MILAGRO 2006 field campaign, the exchange of atmospheric aerosols with the urban landscape was measured from a tall tower erected in a heavily populated neighborhood of Mexico City. Urban submicron aerosol fluxes were measured using an eddy covariance method with a quadrupole aerosol mass spectrometer during a two week period in March, 2006. Nitrate and ammonium aerosol concentrations were elevated at this location near the city center compared to measurements at other urban sites. Significant downward fluxes of nitrate aerosol, averaging -0.2 μg m-2 s-1, were measured during daytime. The urban surface was not a significant source of sulfate aerosols. The measurements also showed that primary organic aerosol fluxes, approximated by hydrocarbon-like organic aerosols (HOA), displayed diurnal patterns similar to CO2 fluxes and anthropogenic urban activities. Overall, 47% of submicron organic aerosol emissions were HOA, 35% were oxygenated (OOA) and 18% were associated with biomass burning (BBOA). Organic aerosol fluxes were bi-directional, but on average HOA fluxes were 0.1 μg m-2 s-1, OOA fluxes were -0.03 μg m-2 s-1, and BBOA fluxes were -0.03 μg m-2 s-1. After accounting for size differences (PM1 vs PM2.5) and using an estimate of the black carbon component, comparison of the flux measurements with the 2006 gridded emissions inventory of Mexico City, showed that the daily-averaged total PM emission rates were essentially identical for the emission inventory and the flux measurements. However, the emission inventory included dust and metal particulate contributions, which were not included in the flux measurements. As a result, it appears that the inventory underestimates overall PM emissions for this location.

  11. A review of measurement-based assessments of the aerosol direct radiative effect and forcing

    Directory of Open Access Journals (Sweden)

    H. Yu

    2006-01-01

    contamination of the satellite derived aerosol field will reduce the TOA DRE to -5.0 Wm-2. Because of a lack of measurements of aerosol absorption and difficulty in characterizing land surface reflection, estimates of DRE over land and at the ocean surface are currently realized through a combination of satellite retrievals, surface measurements, and model simulations, and are less constrained. Over the oceans the surface DRE is estimated to be -8.8±0.7 Wm-2. Over land, an integration of satellite retrievals and model simulations derives a DRE of -4.9±0.7 Wm-2 and -11.8±1.9 Wm-2 at the TOA and surface, respectively. CTM simulations derive a wide range of DRE estimates that on average are smaller than the measurement-based DRE by about 30-40%, even after accounting for thin cirrus and cloud contamination. A number of issues remain. Current estimates of the aerosol direct effect over land are poorly constrained. Uncertainties of DRE estimates are also larger on regional scales than on a global scale and large discrepancies exist between different approaches. The characterization of aerosol absorption and vertical distribution remains challenging. The aerosol direct effect in the thermal infrared range and in cloudy conditions remains relatively unexplored and quite uncertain, because of a lack of global systematic aerosol vertical profile measurements. A coordinated research strategy needs to be developed for integration and assimilation of satellite measurements into models to constrain model simulations. Enhanced measurement capabilities in the next few years and high-level scientific cooperation will further advance our knowledge.

  12. Atmospheric Polarization Imaging with Variable Aerosols, Clouds, and Surface Albedo

    Science.gov (United States)

    2013-07-01

    Continuous outdoor operation of an all-sky polarization imager,” Proc. SPIE 7672 (Polarization: Measurement, Analysis , and Remote Sensing IX), 76720A-1-7, 7...condensation nuclei activity and hygroscopicity of in-situ biomass burning aerosol,” American Assoc. Aerosol Research 31 st Annual Conference...tunable liquid crystal variable retarders (LCVRs) allows the API to achieve much faster Stokes-image acquisition than instruments that rely on

  13. Effect of Aerosols on Surface Radiation and Air Quality in the Central American Region Estimated Using Satellite UV Instruments

    Science.gov (United States)

    Bhartia, P. K.; Torres, O.; Krotkov, N. A.

    2007-05-01

    Solar radiation reaching the Earth's surface is reduced by both aerosol scattering and aerosol absorption. Over many parts of the world the latter effect can be as large or larger than the former effect, and small changes in the aerosol single scattering albedo can either cancel the former effect or enhance it. In addition, absorbing aerosols embedded in clouds can greatly reduce the amount of radiation reaching the surface by multiple scattering. Though the potential climatic effects of absorbing aerosols have received considerable attention lately, their effect on surface UV, photosynthesis, and photochemistry can be equally important for our environment and may affect human health and agricultural productivity. Absorption of all aerosols commonly found in the Earth's atmosphere becomes larger in the UV and blue wavelengths and has a relatively strong wavelength dependence. This is particularly true of mineral dust and organic aerosols. However, these effects have been very difficult to estimate on a global basis since the satellite instruments that operate in the visible are primarily sensitive to aerosol scattering. A notable exception is the UV Aerosol Index (AI), first produced using NASA's Nimbus-7 TOMS data. AI provides a direct measure of the effect of aerosol absorption on the backscattered UV radiation in both clear and cloudy conditions, as well as over snow/ice. Although many types of aerosols produce a distinct color cast in the visible images, and aerosols absorption over clouds and snow/ice could, in principle be detected from their color, so far this technique has worked well only in the UV. In this talk we will discuss what we have learned from the long-term record of AI produced from TOMS and Aura/OMI about the possible role of aerosols on surface radiation and air quality in the Central American region.

  14. Synergy of Satellite-Surface Observations for Studying the Properties of Absorbing Aerosols in Asia

    Science.gov (United States)

    Tsay, Si-Chee

    2010-01-01

    Through interaction with clouds and alteration of the Earth's radiation budget, atmospheric aerosols significantly influence our weather and climate. Monsoon rainfalls, for example, sustain the livelihood of more than half of the world's population. Thus, understanding the mechanism that drives the water cycle and freshwater distribution is high-lighted as one of the major near-term goals in NASA's Earth Science Enterprise Strategy. Every cloud droplet/ice-crystal that serves as an essential element in portraying water cycle and distributing freshwater contains atmospheric aerosols at its core. In addition, the spatial and temporal variability of atmospheric aerosol properties is complex due to their dynamic nature. In fact, the predictability of the tropical climate system is much reduced during the boreal spring, which is associated with the peak season of biomass burning activities and regional/long-range transport of dust aerosols. Therefore, to accurately assess the impact of absorbing aerosols on regional-to-global climate requires not only modeling efforts but also continuous observations from satellites, aircraft, networks of ground-based instruments and dedicated field experiments. Since 1997 NASA has been successfully launching a series of satellites the Earth Observing System - to intensively study, and gain a better understanding of, the Earth as an integrated system. Through participation in many satellite remote-sensing/retrieval and validation projects over the years, we have gradually developed and refined the SMART (Surface-sensing Measurements for Atmospheric Radiative Transfer) and COMMIT (Chemical, Optical & Microphysical Measurements of In-situ Troposphere) mobile observatories, a suite of surface remote sensing and in-situ instruments that proved to be vital in providing high temporal measurements, which complement the satellite observations. In this talk, we will present SMART-COMMIT which has played key roles, serving as network or supersite

  15. Estimation of Downwelling Surface Longwave Radiation under Heavy Dust Aerosol Sky

    Directory of Open Access Journals (Sweden)

    Chunlei Wang

    2017-02-01

    Full Text Available The variation of aerosols, especially dust aerosol, in time and space plays an important role in climate forcing studies. Aerosols can effectively reduce land surface longwave emission and re-emit energy at a colder temperature, which makes it difficult to estimate downwelling surface longwave radiation (DSLR with satellite data. Using the latest atmospheric radiative transfer code (MODTRAN 5.0, we have simulated the outgoing longwave radiation (OLR and DSLR under different land surface types and atmospheric profile conditions. The results show that dust aerosol has an obvious “warming” effect to longwave radiation compared with other aerosols; that aerosol longwave radiative forcing (ALRF increased with the increasing of aerosol optical depth (AOD; and that the atmospheric water vapor content (WVC is critical to the understanding of ALRF. A method is proposed to improve the accuracy of DSLR estimation from satellite data for the skies under heavy dust aerosols. The AOD and atmospheric WVC under cloud-free conditions with a relatively simple satellite-based radiation model yielding the high accurate DSLR under heavy dust aerosol are used explicitly as model input to reduce the effects of dust aerosol on the estimation of DSLR. Validations of the proposed model with satellites data and field measurements show that it can estimate the DSLR accurately under heavy dust aerosol skies. The root mean square errors (RMSEs are 20.4 W/m2 and 24.2 W/m2 for Terra and Aqua satellites, respectively, at the Yingke site, and the biases are 2.7 W/m2 and 9.6 W/m2, respectively. For the Arvaikheer site, the RMSEs are 23.2 W/m2 and 19.8 W/m2 for Terra and Aqua, respectively, and the biases are 7.8 W/m2 and 10.5 W/m2, respectively. The proposed method is especially applicable to acquire relatively high accurate DSLR under heavy dust aerosol using MODIS data with available WVC and AOD data.

  16. Seasonal fluctuations of the uranium and thorium contents in aerosols in surface air

    International Nuclear Information System (INIS)

    Kolb, W.

    1985-01-01

    An estimate in the UNSCEAR report the only source considered for the uranium and thorium contents is ground dust. A significant portion of the aerosols, however, comes from chimneys. Aerosol samples taken monthly in Brunswick, Berlin, Skibotn (Northern Norway) were, therefore, scrutinized alpha-spectrometrically for U-238, U-234, Th-230, and Th-232. The activity concentration in surface air of Northern Norway is only about 30 nBq/cm 3 . In Brunswick and Berlin, the concentration was higher by a factor of one to two due to the higher specific activity of the mineral aerosols. Significant differences of the isotope ratios allow conclusions as to the origin of the aerosols. The activity concentrations measured and their seasonal fluctuations must be taken into account in the evaluation of environment monitoring of nuclear fuel factories. (orig./HP) [de

  17. Surface Shortwave and Longe Wave Solar Radiation Atmospheric Aerosols Radiative Forcing Using Sunphotometer , Modis Satellite and Cnr -1 Measurements Over Western Indian Tropical Site or Udaipur ( 24.57N, 73. 69E, 588M Asl)

    Science.gov (United States)

    Vyas, B. M.

    2017-12-01

    The analysis of investigation describes the experimental results of monthly surafcae short wave radiative(SWR) and longwave radaitive(LWR) atmospheric aerosols radaitive forcing derived from daily mesaured values of AOD at 550 nm from MODIS Terra and Acqau satellite as well as hourly measurement of AOD at 500nm from MICROTOPS _II sunsphotometer ( M/S Solar Light Co. USA) with round the clock of 24 hourly measurement of CNR-1 ( M/s KIP & ZONN, Netherland) during the clear sky days over Udaipur. For the present investigation, such above simulatneous daily data sets of period from Oct.,2011 to June 2017 were used to study the monthly and sesaonal ground level SWR and LWR over a semi- urban and semi-arid western Indian tropical site for pre- monsoon, post-monsoon and winter months. In this study, a well known method of computing surface SWR and LWR has been employed as Method -1 as suggested by Shrivastava et al., 2011. A stong and distinct different sesaonal surface SWR and LWR due to atmospheric aerosols has observed that the well defined seasonal neagtive SWR is observed maximum in pre- monsoon and minimum in winter and post-monsoon months. But in contary to the above, higher positive monthly LWR values are noticed in pre-monsoon as compared to in winter months. The The inter- annual sesaonal trend of the SWR and LWR are also noticed in the present work. The reslts of present study will be compared with other availlable simillar study using SBDART at other other Indian stations.

  18. MODIFICATION OF SURFACE KONDENSITSIONNYH AEROSOLS WELDING AND METALLURGICHESKIH PRODUCTIONS

    Directory of Open Access Journals (Sweden)

    A. A. Ennan

    2016-04-01

    Full Text Available Chemical modification of surface kondensitsionnyh aerosols (KA which formation when heat treatment metals (process of weld, foundry processes with application chlorosilanes are suggested. Adsorbtion vapor of water on modification powders KA decreases and changes in varies from modifier and conditions modification are setted.

  19. Development and Characterization of a Thermodenuder for Aerosol Volatility Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Timothy Onasch

    2009-09-09

    This SBIR Phase I project addressed the critical need for improved characterization of carbonaceous aerosol species in the atmosphere. The proposed work focused on the development of a thermodenuder (TD) system capable of systematically measuring volatility profiles of primary and secondary organic aerosol species and providing insight into the effects of absorbing and nonabsorbing organic coatings on particle absorption properties. This work provided the fundamental framework for the generation of essential information needed for improved predictions of ambient aerosol loadings and radiative properties by atmospheric chemistry models. As part of this work, Aerodyne Research, Inc. (ARI) continued to develop and test, with the final objective of commercialization, an improved thermodenuder system that can be used in series with any aerosol instrument or suite of instruments (e.g., aerosol mass spectrometers-AMS, scanning mobility particle sizers-SMPS, photoacoustic absorption spectrometers-PAS, etc.) to obtain aerosol chemical, physical, and optical properties as a function of particle volatility. In particular, we provided the proof of concept for the direct coupling of our improved TD design with a full microphysical model to obtain volatility profiles for different organic aerosol components and to allow for meaningful comparisons between different TD-derived aerosol measurements. In a TD, particles are passed through a heated zone and a denuding (activated charcoal) zone to remove semi-volatile material. Changes in particle size, number concentration, optical absorption, and chemical composition are subsequently detected with aerosol instrumentation. The aerosol volatility profiles provided by the TD will strengthen organic aerosol emission inventories, provide further insight into secondary aerosol formation mechanisms, and provide an important measure of particle absorption (including brown carbon contributions and identification, and absorption enhancements

  20. Estimation of aerosol water and chemical composition from AERONET Sun-sky radiometer measurements at Cabauw, the Netherlands

    NARCIS (Netherlands)

    Van Beelen, A. J.; Roelofs, G. J H; Hasekamp, O. P.; Henzing, J. S.; Röckmann, T.

    2014-01-01

    Remote sensing of aerosols provides important information on atmospheric aerosol abundance. However, due to the hygroscopic nature of aerosol particles observed aerosol optical properties are influenced by atmospheric humidity, and the measurements do not unambiguously characterize the aerosol dry

  1. Aerosol Retrieval Sensitivity and Error Analysis for the Cloud and Aerosol Polarimetric Imager on Board TanSat: The Effect of Multi-Angle Measurement

    Directory of Open Access Journals (Sweden)

    Xi Chen

    2017-02-01

    Full Text Available Aerosol scattering is an important source of error in CO2 retrievals from satellite. This paper presents an analysis of aerosol information content from the Cloud and Aerosol Polarimetric Imager (CAPI onboard the Chinese Carbon Dioxide Observation Satellite (TanSat to be launched in 2016. Based on optimal estimation theory, aerosol information content is quantified from radiance and polarization observed by CAPI in terms of the degrees of freedom for the signal (DFS. A linearized vector radiative transfer model is used with a linearized Mie code to simulate observation and sensitivity (or Jacobians with respect to aerosol parameters. In satellite nadir mode, the DFS for aerosol optical depth is the largest, but for mode radius, it is only 0.55. Observation geometry is found to affect aerosol DFS based on the aerosol scattering phase function from the comparison between different viewing zenith angles or solar zenith angles. When TanSat is operated in target mode, we note that multi-angle retrieval represented by three along-track measurements provides additional 0.31 DFS on average, mainly from mode radius. When adding another two measurements, the a posteriori error decreases by another 2%–6%. The correlation coefficients between retrieved parameters show that aerosol is strongly correlated with surface reflectance, but multi-angle retrieval can weaken this correlation.

  2. Inverse modeling of cloud-aerosol interactions -- Part 1: Detailed response surface analysis

    NARCIS (Netherlands)

    Partridge, D.G.; Vrugt, J.A.; Tunved, P.; Ekman, A.M.L.; Gorea, D.; Sooroshian, A.

    2011-01-01

    New methodologies are required to probe the sensitivity of parameters describing cloud droplet activation. This paper presents an inverse modeling-based method for exploring cloud-aerosol interactions via response surfaces. The objective function, containing the difference between the measured and

  3. Workplace aerosol mass concentration measurement using optical particle counters.

    Science.gov (United States)

    Görner, Peter; Simon, Xavier; Bémer, Denis; Lidén, Göran

    2012-02-01

    Direct-reading aerosol measurement usually uses the optical properties of airborne particles to detect and measure particle concentration. In the case of occupational hygiene, mass concentration measurement is often required. Two aerosol monitoring methods are based on the principle of light scattering: optical particle counting (OPC) and photometry. The former analyses the light scattered by a single particle, the latter by a cloud of particles. Both methods need calibration to transform the quantity of scattered light detected into particle concentration. Photometers are simpler to use and can be directly calibrated to measure mass concentration. However, their response varies not only with aerosol concentration but also with particle size distribution, which frequently contributes to biased measurement. Optical particle counters directly measure the particle number concentration and particle size that allows assessment of the particle mass provided the particles are spherical and of known density. An integrating algorithm is used to calculate the mass concentration of any conventional health-related aerosol fraction. The concentrations calculated thus have been compared with simultaneous measurements by conventional gravimetric sampling to check the possibility of field OPC calibration with real workplace aerosols with a view to further monitoring particle mass concentration. Aerosol concentrations were measured in the food industry using the OPC GRIMM® 1.108 and the CIP 10-Inhalable and CIP 10-Respirable (ARELCO®) aerosol samplers while meat sausages were being brushed and coated with calcium carbonate. Previously, the original OPC inlet had been adapted to sample inhalable aerosol. A mixed aerosol of calcium carbonate and fungi spores was present in the workplace. The OPC particle-size distribution and an estimated average particle density of both aerosol components were used to calculate the mass concentration. The inhalable and respirable aerosol fractions

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

    Science.gov (United States)

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

  5. Real-time measurement of aerosol particle concentration at high temperatures; Hiukkaspitoisuuden reaaliaikainen mittaaminen korkeassa laempoetilassa

    Energy Technology Data Exchange (ETDEWEB)

    Keskinen, J.; Hautanen, J.; Laitinen, A. [Tampere Univ. of Technology (Finland). Physics

    1997-10-01

    The aim of this project is to develop a new method for continuous aerosol particle concentration measurement at elevated temperatures (up to 800-1000 deg C). The measured property of the aerosol particles is the so called Fuchs surface area. This quantity is relevant for diffusion limited mass transfer to particles. The principle of the method is as follows. First, aerosol particles are charged electrically by diffusion charging process. The charging takes place at high temperature. After the charging, aerosol is diluted and cooled. Finally, aerosol particles are collected and the total charge carried by the aerosol particles is measured. Particle collection and charge measurement take place at low temperature. Benefits of this measurement method are: particles are charged in-situ, charge of the particles is not affected by the temperature and pressure changes after sampling, particle collection and charge measurement are carried out outside the process conditions, and the measured quantity is well defined. The results of this study can be used when the formation of the fly ash particles is studied. Another field of applications is the study and the development of gasification processes. Possibly, the method can also be used for the monitoring the operation of the high temperature particle collection devices. (orig.)

  6. First surface-based estimation of the aerosol indirect effect over a site in southeastern China

    Science.gov (United States)

    Liu, Jianjun; Li, Zhanqing

    2018-02-01

    The deployment of the U.S. Atmospheric Radiation Measurement mobile facility in Shouxian from May to December 2008 amassed the most comprehensive set of measurements of atmospheric, surface, aerosol, and cloud variables in China. This deployment provided a unique opportunity to investigate the aerosol-cloud interactions, which are most challenging and, to date, have not been examined to any great degree in China. The relationship between cloud droplet effective radius (CER) and aerosol index (AI) is very weak in summer because the cloud droplet growth is least affected by the competition for water vapor. Mean cloud liquid water path (LWP) and cloud optical depth (COD) significantly increase with increasing AI in fall. The sensitivities of CER and LWP to aerosol loading increases are not significantly different under different air mass conditions. There is a significant correlation between the changes in hourly mean AI and the changes in hourly mean CER, LWP, and COD. The aerosol first indirect effect (FIE) is estimated in terms of relative changes in both CER (FIECER) and COD (FIECOD) with changes in AI for different seasons and air masses. FIECOD and FIECER are similar in magnitude and close to the typical FIE value of ˜ 0.23, and do not change much between summer and fall or between the two different air mass conditions. Similar analyses were done using spaceborne Moderate Resolution Imaging Spectroradiometer data. The satellite-derived FIE is contrary to the FIE estimated from surface retrievals and may have large uncertainties due to some inherent limitations.

  7. A Simple and Universal Aerosol Retrieval Algorithm for Landsat Series Images Over Complex Surfaces

    Science.gov (United States)

    Wei, Jing; Huang, Bo; Sun, Lin; Zhang, Zhaoyang; Wang, Lunche; Bilal, Muhammad

    2017-12-01

    Operational aerosol optical depth (AOD) products are available at coarse spatial resolutions from several to tens of kilometers. These resolutions limit the application of these products for monitoring atmospheric pollutants at the city level. Therefore, a simple, universal, and high-resolution (30 m) Landsat aerosol retrieval algorithm over complex urban surfaces is developed. The surface reflectance is estimated from a combination of top of atmosphere reflectance at short-wave infrared (2.22 μm) and Landsat 4-7 surface reflectance climate data records over densely vegetated areas and bright areas. The aerosol type is determined using the historical aerosol optical properties derived from the local urban Aerosol Robotic Network (AERONET) site (Beijing). AERONET ground-based sun photometer AOD measurements from five sites located in urban and rural areas are obtained to validate the AOD retrievals. Terra MODerate resolution Imaging Spectrometer Collection (C) 6 AOD products (MOD04) including the dark target (DT), the deep blue (DB), and the combined DT and DB (DT&DB) retrievals at 10 km spatial resolution are obtained for comparison purposes. Validation results show that the Landsat AOD retrievals at a 30 m resolution are well correlated with the AERONET AOD measurements (R2 = 0.932) and that approximately 77.46% of the retrievals fall within the expected error with a low mean absolute error of 0.090 and a root-mean-square error of 0.126. Comparison results show that Landsat AOD retrievals are overall better and less biased than MOD04 AOD products, indicating that the new algorithm is robust and performs well in AOD retrieval over complex surfaces. The new algorithm can provide continuous and detailed spatial distributions of AOD during both low and high aerosol loadings.

  8. Aerosols, light, and water: Measurements of aerosol optical properties at different relative humidities

    Science.gov (United States)

    Orozco, Daniel

    The Earth's atmosphere is composed of a large number of different gases as well as tiny suspended particles, both in solid and liquid state. These tiny particles, called atmospheric aerosols, have an immense impact on our health and on our global climate. Atmospheric aerosols influence the Earth's radiation budget both directly and indirectly. In the direct effect, aerosols scatter and absorb sunlight changing the radiative balance of the Earth-atmosphere system. Aerosols indirectly influence the Earth's radiation budget by modifying the microphysical and radiative properties of clouds as well as their water content and lifetime. In ambient conditions, aerosol particles experience hygroscopic growth due to the influence of relative humidity (RH), scattering more light than when the particles are dry. The quantitative knowledge of the RH effect and its influence on the light scattering coefficient and, in particular, on the phase function and polarization of aerosol particles is of substantial importance when comparing ground based observations with other optical aerosol measurements techniques such satellite and sunphotometric retrievals of aerosol optical depth and their inversions. This dissertation presents the aerosol hygroscopicity experiment investigated using a novel dryer-humidifier system, coupled to a TSI-3563 nephelometer, to obtain the light scattering coefficient (sp) as a function of relative humidity (RH) in hydration and dehydration modes. The measurements were performed in Porterville, CA (Jan 10-Feb 6, 2013), Baltimore, MD (Jul 3-30, 2013), and Golden, CO (Jul 12-Aug 10, 2014). Observations in Porterville and Golden were part of the NASA-sponsored DISCOVER-AQ project. The measured sp under varying RH in the three sites was combined with ground aerosol extinction, PM2:5mass concentrations, particle composition measurements, and compared with airborne observations performed during campaigns. The enhancement factor, f(RH), defined as the ratio of sp

  9. Measurement of the ambient organic aerosol volatility distribution: application during the Finokalia Aerosol Measurement Experiment (FAME-2008

    Directory of Open Access Journals (Sweden)

    B. H. Lee

    2010-12-01

    Full Text Available A variable residence time thermodenuder (TD was combined with an Aerodyne Aerosol Mass Spectrometer (AMS and a Scanning Mobility Particle Sizer (SMPS to measure the volatility distribution of aged organic aerosol in the Eastern Mediterranean during the Finokalia Aerosol Measurement Experiment in May of 2008 (FAME-2008. A new method for the quantification of the organic aerosol volatility distribution was developed combining measurements of all three instruments together with an aerosol dynamics model.

    Challenges in the interpretation of ambient thermodenuder-AMS measurements include the potential resistances to mass transfer during particle evaporation, the effects of particle size on the evaporated mass fraction, the changes in the AMS collection efficiency and particle density as the particles evaporate partially in the TD, and finally potential losses inside the TD. Our proposed measurement and data analysis method accounts for all of these problems combining the AMS and SMPS measurements.

    The AMS collection efficiency of the aerosol that passed through the TD was found to be approximately 10% lower than the collection efficiency of the aerosol that passed through the bypass. The organic aerosol measured at Finokalia is approximately 2 or more orders of magnitude less volatile than fresh laboratory-generated monoterpene (α-pinene, β-pinene and limonene under low NOx conditions secondary organic aerosol. This low volatility is consistent with its highly oxygenated AMS mass spectrum. The results are found to be highly sensitive to the mass accommodation coefficient of the evaporating species. This analysis is based on the assumption that there were no significant reactions taking place inside the thermodenuder.

  10. Aerosol size measurement during the 2004/2005 harmattan season ...

    African Journals Online (AJOL)

    The aerosol size measurement at Uturu (lat.05.33°N, 06.03°N and long. 07.10"E, 07.29°E) Nigeria during the 2004/2005 harmattan season was carried out. The aerosol size distributions were measured using zeiss micrometer inserted on the diaphragm inside the eye piece of Olympus binocular microscope. The dust ...

  11. A critical assessment of direct radiative effects of different aerosol types on surface global radiation and its components

    International Nuclear Information System (INIS)

    Xia, Xiangao

    2014-01-01

    A critical assessment of direct radiative effects of different aerosol types on surface global, direct and diffuse radiation is presented. The analysis is based on measurements of aerosol optical properties and surface solar radiation (SSR) of cloud-free days at the Baseline Surface Radiation Network (BSRN) and Aerosol Robotic Network station (AERONET) of Xianghe over the North China Plain between October 2004 and May 2012. Six aerosol types are classified based on aerosol size and absorption from the AERONET retrieval products, including two coarse-mode dominated aerosol types: dust (DU: fine mode fraction (FMF)<0.4) and polluted dust (PD: FMF within 0.4–0.7) and four fine-mode dominated aerosol types (FMF>0.7) but with different single scattering albedo (SSA): highly absorbing (HA: SSA<0.85), moderately absorbing (MA: SSA within 0.85–0.90), slightly absorbing (SA: SSA within 0.90–0.95) and very weakly absorbing (WA: SSA>0.95). Dramatic differences in aerosol direct radiative effect (ADRE) on global SSR and its components between the six aerosol types have been revealed. ADRE efficiency on global SSR for solar zenight angle (SZA) between 55° and 65° ranges from −106 W m −2 for WA to −181 W m −2 for HA. The minimum ADRE efficiency on diffuse SSR is derived for HA aerosols, being 113 W m −2 that is about half of that by DU, the maximum value of six aerosol types. ADRE efficiency on global SSR by DU and PD (−141 to −150 W m −2 for SZA between 55° and 65°) is comparable to that by MA, although 100 W m −2 more direct SSR is extincted by DU and PD than by MA. DU and PD induce more diffuse SSR than MA that offsets larger reduction of direct SSR by DU and PD. Implications of the results to related researches are detailed discussed. The results are derived from aerosol and radiation data in the North China Plain, however the method can be used to any other stations with similar measurements. - Highlights: • A statistical method is developed to

  12. Measurement of particle size characteristics of metered dose inhaler (MDI) aerosols.

    Science.gov (United States)

    Dolovich, M

    1991-01-01

    Measurement of the aerodynamic size of an aerosol allows a prediction of its deposition efficiency and behaviour in the lung. The dynamics of volatile or pressurized (MDI) aerosols presents problems not encountered in the characterization of solid or liquid particles alone. For example, the data obtained in real-time sampling as opposed to measuring an aged aerosol provide a truer representation of circumstances during actual clinical use, yet this may be difficult to achieve due to propellent evaporation. A number of particle sizing systems have been developed based upon light scattering techniques and aerodynamic principles. Each method has its limitations; in general, they successfully measure the aerodynamic size distributions of MDI aerosols. Cascade impactors, the "gold standard" of the industry have the advantage that they allow analysis of drug mass as well as other tracers within the aerosol, but the process as a whole is labour intensive, with limited resolution. Highly automated laser-based systems developed over the past 10 years measure the surface characteristics of the aerosol rather than the direct measurement of mass. Because of different values obtained from various sizing systems, it is suggested that all MDI drugs be sized using cascade impactors but that parallel data be obtained using an alternative sizing system.

  13. Size segregated aerosol mass concentration measurements over ...

    Indian Academy of Sciences (India)

    significant variations were observed over central and northern Arabian Sea as well as close to .... Arabian Sea. 4. Results and discussion. Total aerosol mass concentration (MT = Σmi, where mi is the mass concentration on the individ- ual stages) varied from the ..... Twomey S A 1977 The influence of pollution on the short-.

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

    Science.gov (United States)

    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. Lidar Measurements of Ozone, Aerosols, and Clouds Observed in the Tropics Near Central America During TC4-Costa Rica

    Science.gov (United States)

    Hair, J. W.; Browell, E.; Butler, C.; Fenn, M.; Notari, A.; Simpson, S.; Ismail, S.; Avery, M.

    2007-12-01

    Large-scale measurements of ozone and aerosol distributions were made from the NASA DC-8 aircraft during the TC4 (Tropical Composition, Cloud, and Climate Coupling) field experiment conducted from June 28 - August 10, 2007 based in San Jose, Costa Rica. Remote measurements were made with an airborne lidar to provide ozone and multiple-wavelength aerosol and cloud backscatter profiles from near the surface to above the tropopause along the flight track. Aerosol depolarization measurements were also made for the detection of nonspherical aerosols, such as mineral dust, biomass burning, and recent emissions from South American volcanoes. Long-range transport of Saharan dust with depolarizing aerosols was frequently observed in the lower troposphere both over the Caribbean Sea and Pacific Ocean and within the marine boundary layer. In addition, visible and sub-visible cirrus clouds were observed with the multi-wavelength backscatter and depolarization measurements. Initial distributions of ozone, aerosol, and cloud are presented which will be used to interpret large-scale atmospheric processes. In situ measurements of ozone and aerosols made onboard the DC-8 will be compared to the remote lidar measurements. This paper provides a first look at the characteristics of ozone, aerosol, and cloud distributions that were encountered during this field experiment and provide a unique dataset that will be further related through satellite data, backward trajectories, and chemical transport models (CTM) to sources and sinks of ozone, aerosols, and clouds and to dynamical, chemical, and radiative processes.

  16. Measurement of size distribution for 220Rn progeny attached aerosols

    International Nuclear Information System (INIS)

    Zhang Lei; Guo Qiuju; Zhuo Weihai

    2008-01-01

    The size distribution of radioactive aerosols is a very important factor for evaluating the inner exposure dose contributed by radon and thoron progeny in environments. In order to measure the size distribution of thoron progeny attached radioactive aerosols, a device was developed using wire screens. The count median diameter (CMD) and the geometric standard deviation (GSD) of attached radioactive aerosols were calculated by collecting ThB and using CR-39 as detector. Field measurement results at Yangjiang City in Guangdong Province show that the CMDs distribute between 30 and 130 nm, and the GSDs are between 1.9 and 3.3. It also shows that the more humid country, the smaller CMDs, and the ventilation has great influence on the size distribution of aerosols. The CMDs of adobe house are smaller than that of the concrete houses. (authors)

  17. Dust Aerosols at the Source Region During ACE-ASIA: A Surface/Satellite Perspective

    Science.gov (United States)

    Tsay, Si-Chee; Lau, William K. M. (Technical Monitor)

    2001-01-01

    ACE (Aerosol Characterization Experiment)-Asia is designed to study the compelling variability in spatial and temporal scale of both pollution-derived and naturally occurring aerosols, which often exist in high concentrations over eastern Asia and along the rim of the western Pacific. The phase-I of ACE-Asia was conducted from March-May 2001 in the vicinity of the Gobi desert, East Coast of China, Yellow Sea, Korea, and Japan, along the pathway of Kosa (severe events that blanket East Asia with yellow desert dust, peaked in the Spring season). Asian dust typically originates in desert areas far from polluted urban regions. During transport, dust layers can interact with anthropogenic sulfate and soot aerosols from heavily polluted urban areas. Added to the complex effects of clouds and natural marine aerosols, dust particles reaching the marine environment can have drastically different properties than those from the source. Thus, understanding the unique temporal and spatial variations of Asian dust is of special importance in regional-to-global climate issues such as radiative forcing, the hydrological cycle, and primary biological productivity in the mid-Pacific Ocean. During ACE-Asia we have measured continuously aerosol physical/optical/radiative properties, column precipitable water amount, and surface reflectivity over homogeneous areas from surface. The inclusion of flux measurements permits the determination of dust aerosol radiative flux in addition to measurements of loading and optical thickness. At the time of the Terra/MODIS, SeaWiFS, TOMS and other satellite overpasses, these ground-based observations can provide valuable data to compare with satellite retrievals over land. Preliminary results will be presented and discussed their implications in regional climatic effects.

  18. Light Source Effects on Aerosol Photoacoustic Spectroscopy Measurements

    OpenAIRE

    Radney, James G.; Zangmeister, Christopher D.

    2016-01-01

    Photoacoustic spectroscopy measurements of flame-generated soot aerosol coated with small amounts of water yielded absorption enhancements that were dependent on the laser used: quasi-continuous wave (Q-CW, ≈ 650 ps pulse duration and 78 MHz repetition rate) versus continuous wave (CW). Water coating thickness was controlled by exposing the aerosol to a set relative humidity (RH). At ≈ 85 % RH, the mass of the soot particles increased by an amount comparable to a monolayer of water being depo...

  19. Aerosol Composition and Variability in Baltimore Measured during DISCOVER-AQ

    Science.gov (United States)

    Beyersdorf, A. J.; Ziemba, L. D.; Chen, G.; Thornhill, K. L.; Winstead, E. L.; Diskin, G. S.; Chatfield, R. B.; Natraj, V.; Anderson, B. E.

    2012-12-01

    In order to relate satellite-based measurements of aerosols to ground-level air quality, the correlation between aerosol optical properties (wavelength-dependent scattering and absorption measured by satellites) and mass measurements of aerosol loading (i.e. PM2.5 used for air quality monitoring) must be understood. This connection varies with many factors including those specific to the aerosol type (such as composition, size, hygroscopicity, and mass scattering and absorption efficiencies) and to the surrounding atmosphere (such as temperature, relative humidity and altitude). The DISCOVER-AQ (Deriving Information on Surface conditions from COlumn and VERtically resolved observations relevant to Air Quality) project was designed to provide a unique dataset for determining variability in and correlations between aerosol loading, composition, optical properties and meteorological conditions. Extensive in-situ profiling of the lower atmosphere in the Baltimore-Washington D.C. region was performed during fourteen flights during July 2011. Identical flight plans and profile locations throughout the campaign provide meaningful statistics for analysis. Measured aerosol mass was composed primarily of ammonium sulfate (campaign average of 36%) and water-soluble organics (58%). A distinct difference in composition was related to aerosol loading with high-loading days having a proportionally larger percentage of ammonium sulfate (up to 60%). This composition shift causes a change in the water-uptake potential (hygroscopicity) of the aerosols with higher relative organic composition decreasing water-uptake. On average, sulfate mass increased during the day due to increased photochemistry, while organics decreased. Analysis of the linkage between aerosol loading and optical properties was also performed. The absorption by black carbon was dependent on the amount of organic coating with an increase in mass absorption efficiency from 7.5 m2/g for bare soot to 16 m2/g at an

  20. Surface cleanliness measurement procedure

    Science.gov (United States)

    Schroder, Mark Stewart; Woodmansee, Donald Ernest; Beadie, Douglas Frank

    2002-01-01

    A procedure and tools for quantifying surface cleanliness are described. Cleanliness of a target surface is quantified by wiping a prescribed area of the surface with a flexible, bright white cloth swatch, preferably mounted on a special tool. The cloth picks up a substantial amount of any particulate surface contamination. The amount of contamination is determined by measuring the reflectivity loss of the cloth before and after wiping on the contaminated system and comparing that loss to a previous calibration with similar contamination. In the alternative, a visual comparison of the contaminated cloth to a contamination key provides an indication of the surface cleanliness.

  1. Comparison of Summer and Winter California Central Valley Aerosol Distributions from Lidar and MODIS Measurements

    Science.gov (United States)

    Lewis, Jasper R., Jr.; DeYoung, Russell J.; Chu, D. Allen

    2010-01-01

    Aerosol distributions from two aircraft lidar campaigns conducted in the California Central Valley are compared in order to identify seasonal variations. Aircraft lidar flights were conducted in June 2003 and February 2008. While the PM2.5 concentration is highest in the winter, the aerosol optical depth measured from MODIS is highest in the summer. A seasonal comparison shows that PM2.5 in the winter can exceed summer PM2.5 by 55%, while summer AOD exceeds winter AOD by 43%. Higher temperatures wildfires in the summer produce elevated aerosol layers that are detected by satellite measurements, but not surface particulate matter monitors. Measurements of the boundary layer height from lidar instruments are necessary to incorporate satellite measurements with air quality measurements.

  2. Chemical Thermodynamics of Aqueous Atmospheric Aerosols: Modeling and Microfluidic Measurements

    Science.gov (United States)

    Nandy, L.; Dutcher, C. S.

    2017-12-01

    Accurate predictions of gas-liquid-solid equilibrium phase partitioning of atmospheric aerosols by thermodynamic modeling and measurements is critical for determining particle composition and internal structure at conditions relevant to the atmosphere. Organic acids that originate from biomass burning, and direct biogenic emission make up a significant fraction of the organic mass in atmospheric aerosol particles. In addition, inorganic compounds like ammonium sulfate and sea salt also exist in atmospheric aerosols, that results in a mixture of single, double or triple charged ions, and non-dissociated and partially dissociated organic acids. Statistical mechanics based on a multilayer adsorption isotherm model can be applied to these complex aqueous environments for predictions of thermodynamic properties. In this work, thermodynamic analytic predictive models are developed for multicomponent aqueous solutions (consisting of partially dissociating organic and inorganic acids, fully dissociating symmetric and asymmetric electrolytes, and neutral organic compounds) over the entire relative humidity range, that represent a significant advancement towards a fully predictive model. The model is also developed at varied temperatures for electrolytes and organic compounds the data for which are available at different temperatures. In addition to the modeling approach, water loss of multicomponent aerosol particles is measured by microfluidic experiments to parameterize and validate the model. In the experimental microfluidic measurements, atmospheric aerosol droplet chemical mimics (organic acids and secondary organic aerosol (SOA) samples) are generated in microfluidic channels and stored and imaged in passive traps until dehydration to study the influence of relative humidity and water loss on phase behavior.

  3. Aircraft measurement of organic aerosols over China.

    Science.gov (United States)

    Wang, Gehui; Kawamura, Kimitaka; Hatakeyama, Shiro; Takami, Akinori; Li, Hong; Wang, Wei

    2007-05-01

    Lower to middle (0.5-3.0 km altitude) tropospheric aerosols (PM2.5) collected by aircraft over inland and east coastal China were, for the first time, characterized for organic molecular compositions to understand anthropogenic, natural, and photochemical contribution to the air quality. n-Alkanes, fatty acids, sugars, polyacids are detected as major compound classes, whereas lignin and resin products, sterols, polycyclic aromatic hydrocarbons, and phthalic acids are minor species. Average concentrations of all the identified compounds excluding malic acid correspond to 40-50% of those reported on the ground sites. Relative abundances of secondary organic aerosol (SOA) components such as malic acid are much higher in the aircraft samples, suggesting an enhanced photochemical production over China. Organic carbon (OC) concentrations in summer (average, 24.3 microg m(-3)) were equivalent to those reported on the ground sites. Higher OC/EC (elemental carbon) ratios in the summer aircraft samples also support a significant production of SOA over China. High loadings of organic aerosols in the Chinese troposphere may be responsible to an intercontinental transport of the pollutants and potential impact on the regional and global climate changes.

  4. Broadband measurements of aerosol extinction in the ultraviolet spectral region

    Directory of Open Access Journals (Sweden)

    R. A. Washenfelder

    2013-04-01

    Full Text Available Aerosols influence the Earth's radiative budget by scattering and absorbing incoming solar radiation. The optical properties of aerosols vary as a function of wavelength, but few measurements have reported the wavelength dependence of aerosol extinction cross sections and complex refractive indices. We describe a new laboratory instrument to measure aerosol optical extinction as a function of wavelength, using cavity enhanced spectroscopy with a broadband light source. The instrument consists of two broadband channels which span the 360–390 and 385–420 nm spectral regions using two light emitting diodes (LED and a grating spectrometer with charge-coupled device (CCD detector. We determined aerosol extinction cross sections and directly observed Mie scattering resonances for aerosols that are purely scattering (polystyrene latex spheres and ammonium sulfate, slightly absorbing (Suwannee River fulvic acid, and strongly absorbing (nigrosin dye. We describe an approach for retrieving refractive indices as a function of wavelength from the measured extinction cross sections over the 360–420 nm wavelength region. The retrieved refractive indices for PSL and ammonium sulfate agree within uncertainty with the literature values for this spectral region. The refractive index determined for nigrosin is 1.78 (± 0.03 + 0.19 (± 0.08i at 360 nm and 1.63 (± 0.03 + 0.21 (± 0.05i at 420 nm. The refractive index determined for Suwannee River fulvic acid is 1.71 (± 0.02 + 0.07 (± 0.06i at 360 nm and 1.66 (± 0.02 + 0.06 (± 0.04i at 420 nm. These laboratory results support the potential for a field instrument capable of determining ambient aerosol optical extinction, average aerosol extinction cross section, and complex refractive index as a function of wavelength.

  5. Light absorption by pollution, dust, and biomass burning aerosols: a global model study and evaluation with AERONET measurements

    Directory of Open Access Journals (Sweden)

    Mian Chin

    2009-09-01

    Full Text Available Atmospheric aerosol distributions from 2000 to 2007 are simulated with the Goddard Chemistry Aerosol Radiation and Transport (GOCART model to attribute light absorption by aerosol to its composition and sources from pollution, dust, and biomass burning. The 8-year, global averaged total aerosol optical depth (τ, absorption optical depth (τa, and single scattering albedo (ω at 550 nm are estimated at 0.14, 0.0086, and 0.95, respectively, with sulfate making the largest fraction of τ (37%, followed by dust (30%, sea salt (16%, organic matter (OM (13%, and black carbon (BC (4%. BC and dust account for 43% and 53% of τa, respectively. From a model experiment with "tagged" sources, natural aerosols are estimated to be 58% of τ and 53% of τa, with pollution and biomass burning aerosols to share the rest. Comparing with data from the surface sunphotometer network AERONET, the model tends to reproduce much better the AERONET direct measured data of τ and the Ångström exponent (α than its retrieved quantities of ω and τa. Relatively small in its systematic bias of τ for pollution and dust regions, the model tends to underestimate τ for biomass burning aerosols by 30–40%. The modeled α is 0.2–0.3 too low (particle too large for pollution and dust aerosols but 0.2–0.3 too high (particle too small for the biomass burning aerosols, indicating errors in particle size distributions in the model. Still, the model estimated ω is lower in dust regions and shows a much stronger wavelength dependence for biomass burning aerosols but a weaker one for pollution aerosols than those quantities from AERONET. These comparisons necessitate model improvements on aerosol size distributions, the refractive indices of dust and black carbon aerosols, and biomass burning emissions in order to better quantify the aerosol absorption in the atmosphere.

  6. Impact of aerosol on surface reaching solar irradiance over Mohal in the northwestern Himalaya, India

    Science.gov (United States)

    Guleria, Raj Paul; Kuniyal, Jagdish Chandra; Dhyani, Pitamber Prasad; Joshi, Ranjan; Sharma, Nand Lal

    2014-02-01

    The present study, for the first time during 2007, is focused to examine the impact of aerosols on surface reaching solar irradiance over Mohal (31.9°N, 77.12°E, 1154 m amsl) in the northwestern part of the Indian Himalaya. The study also aims to estimate shortwave aerosol radiative forcing (SWARF) and its effect on regional climate. The multi-wavelength solar radiometer (MWR) is used to measure aerosol optical depth (AOD) over a wider spectrum, i.e. ultraviolet, visible and near-infrared. The AOD is obtained by analyzing the data from MWR following the Langley technique. The radiative transfer model is used along with Optical Properties of Aerosols and Clouds model to estimate the SWARF. Aerosol shows a great efficiency to reduce substantial fraction of energy from the surface reaching direct solar beam, i.e. 154 W m-2 μm-1 per unit AOD at 0.5 μm. The SWARF at the surface, top of the atmosphere and the atmosphere is estimated to be -18.5±1.7, +0.6±3.7 and +19.1±3.1 W m-2, respectively. The large SWARF at the surface stood during the summer (April-July), while small during the monsoon (August-September). Moderate SWARF is obtained in the autumn (October-November) and winter (December-March). The study estimates a notable extinction in incoming solar radiation relatively with lower atmospheric heating from 0.41 to 0.73 K day-1. The potential effect of aerosol is found relatively higher on high aerosol loading days. On these days, the lower atmospheric heating increases by a factor 1.8 (during dust events) and 1.7 (during biomass burning). This study concludes that aerosols produce significant reduction in incoming solar radiation with substantial increase in lower atmospheric heating, leading to a remarkable effect on the atmospheric stability. In addition, as a subject of future interest, the present study has also important implications on the atmospheric circulation and regional climate.

  7. Calculating Capstone depleted uranium aerosol concentrations from beta activity measurements.

    Science.gov (United States)

    Szrom, Frances; Falo, Gerald A; Parkhurst, Mary Ann; Whicker, Jeffrey J; Alberth, David P

    2009-03-01

    Beta activity measurements were used as surrogate measurements of uranium mass in aerosol samples collected during the field testing phase of the Capstone Depleted Uranium (DU) Aerosol Study. These aerosol samples generated by the perforation of armored combat vehicles were used to characterize the DU source term for the subsequent Human Health Risk Assessment (HHRA) of Capstone aerosols. Establishing a calibration curve between beta activity measurements and uranium mass measurements is straightforward if the uranium isotopes are in equilibrium with their immediate short-lived, beta-emitting progeny. For DU samples collected during the Capstone study, it was determined that the equilibrium between the uranium isotopes and their immediate short-lived, beta-emitting progeny had been disrupted when penetrators had perforated target vehicles. Adjustments were made to account for the disrupted equilibrium and for wall losses in the aerosol samplers. Values for the equilibrium fraction ranged from 0.16 to 1, and the wall loss correction factors ranged from 1 to 1.92. This paper describes the process used and adjustments necessary to calculate uranium mass from proportional counting measurements.

  8. The continuous monitoring of the artificial beta aerosol activity by measuring the alpha and beta activity in aerosol simultaneously

    International Nuclear Information System (INIS)

    Hayakawa, Hironobu; Oonishi, Masaki; Matsuura, Hiroyuki

    1990-01-01

    We have constructed the system to monitor the artificial beta aerosol activity around the nuclear power plants continuously in real time. The smaller releases of artificial radionuclides from the nuclear power plants can be lost in the fluctuations of the natural background of the beta aerosol activity, when only the beta activity of the aerosol is measured. This method to discriminate the artificial and the natural beta activity of the aerosol is based on the fact that the ratio of the natural alpha and beta activities of the aerosol is almost constant. The detection limit of this system is below 3 Bq/m 3 . (author)

  9. MODIS Aerosol Optical Depth retrieval over land considering surface BRDF effects

    Science.gov (United States)

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

    2016-04-01

    Aerosols in the atmosphere play an important role in the climate system and human health. Retrieval from satellite data, Aerosol Optical Depth (AOD), one of most important indices of aerosol optical properties, has been extensively investigated. Benefiting from the high resolution at spatial and temporal and the maturity of the aerosol retrieval algorithm, MOderate Resolution Imaging Spectroradiometer (MODIS) Dark Target AOD product has been extensively applied in other scientific research such as climate change and air pollution. The latest product - MODIS Collection 6 Dark Target AOD (C6_DT) has been released. However, the accuracy of C6_DT AOD (global mean ±0.03) over land is still too low for the constraint on radiative forcing in the climate system, where the uncertainty should be reduced to ±0.02. The major uncertainty mainly lies on the underestimation/overestimation of the surface contribution to the Top Of Atmosphere (TOA) radiance since a lambertian surface is assumed in the C6_DT land algorithm. In the real world, it requires considering the heterogeneity of the surface reflection in the radiative transfer process. Based on this, we developed a new algorithm to retrieve AOD by considering surface Bidirectional Reflectance Distribution Function (BRDF) effects. The surface BRDF is much more complicated than isotropic reflection, described as 4 elements: directional-directional, directional-hemispherical, hemispherical-directional and hemispherical-hemispherical reflectance, and coupled into radiative transfer equation to generate an accurate top of atmosphere reflectance. The limited MODIS measurements (three channels available) allow us to retrieve only three parameters, which including AOD, the surface directional-directional reflectance and fine aerosol ratio η. The other three elements of the surface reflectance are expected to be constrained by ancillary data and assumptions or "a priori" information since there are more unknowns than MODIS

  10. Study of the effect of different type of aerosols on UV-B radiation from measurements during EARLINET

    Directory of Open Access Journals (Sweden)

    D. S. Balis

    2004-01-01

    Full Text Available Routine lidar measurements of the vertical distribution of the aerosol extinction coefficient and the extinction-to-backscatter ratio have been performed at Thessaloniki, Greece using a Raman lidar system in the frame of the EARLINET project since 2000. Co-located spectral and broadband solar UV-B irradiance measurements, as well as total ozone observations, were available whenever lidar measurements were obtained. From the available measurements several cases could be identified that allowed the study of the effect of different types of aerosol on the levels of the UV-B solar irradiance at the Earth's surface. The TUV radiative transfer model has been used to simulate the irradiance measurements, using total ozone and the lidar aerosol data as input. From the comparison of the model results with the measured spectra the effective single scattering albedo was determined using an iterative procedure, which has been verified against results from the 1998 Lindenberg Aerosol Characterization Experiment. It is shown that for the same aerosol optical depth and for the same total ozone values the UV-B irradiances at the Earth's surface can show differences up to 10%, which can be attributed to differences in the aerosol type. It is shown that the combined use of the estimated single scattering albedo and of the measured extinction-to-backscatter ratio leads to a better characterization of the aerosol type probed.

  11. A New Stratospheric Aerosol Product from CALIPSO Lidar Measurements

    Science.gov (United States)

    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

  12. Aerosol light absorption and its measurement: A review

    International Nuclear Information System (INIS)

    Moosmueller, H.; Chakrabarty, R.K.; Arnott, W.P.

    2009-01-01

    Light absorption by aerosols contributes to solar radiative forcing through absorption of solar radiation and heating of the absorbing aerosol layer. Besides the direct radiative effect, the heating can evaporate clouds and change the atmospheric dynamics. Aerosol light absorption in the atmosphere is dominated by black carbon (BC) with additional, significant contributions from the still poorly understood brown carbon and from mineral dust. Sources of these absorbing aerosols include biomass burning and other combustion processes and dust entrainment. For particles much smaller than the wavelength of incident light, absorption is proportional to the particle volume and mass. Absorption can be calculated with Mie theory for spherical particles and with more complicated numerical methods for other particle shapes. The quantitative measurement of aerosol light absorption is still a challenge. Simple, commonly used filter measurements are prone to measurement artifacts due to particle concentration and modification of particle and filter morphology upon particle deposition, optical interaction of deposited particles and filter medium, and poor angular integration of light scattered by deposited particles. In situ methods measure particle absorption with the particles in their natural suspended state and therefore are not prone to effects related to particle deposition and concentration on filters. Photoacoustic and refractive index-based measurements rely on the heating of particles during light absorption, which, for power-modulated light sources, causes an acoustic signal and modulation of the refractive index in the air surrounding the particles that can be quantified with a microphone and an interferometer, respectively. These methods may suffer from some interference due to light-induced particle evaporation. Laser-induced incandescence also monitors particle heating upon absorption, but heats absorbing particles to much higher temperatures to quantify BC mass

  13. Dust, Pollution, and Biomass Burning Aerosols in Asian Pacific: A Column Surface/Satellite Perspective

    Science.gov (United States)

    Tsay, Si-Chee; Lau, William K. M. (Technical Monitor)

    2002-01-01

    Many recent field experiments are designed to study the compelling variability in spatial and temporal scale of both pollution-derived and naturally occurring aerosols, which often exist in high concentrations over eastern/southeastern Asia and along the rim of the western Pacific. For example, the phase-I of ACE-Asia was conducted from March-May 2001 in the vicinity of the Gobi desert, East Coast of China, Yellow Sea, Korea, and Japan, along the pathway of Kosa (severe events that blanket East Asia with yellow desert dust, peaked in the Spring season). Asian dust typically originates in desert areas far from polluted urban regions. During transport, dust layers can interact with anthropogenic sulfate and soot aerosols from heavily polluted urban areas. Springtime is also the peak season for biomass burning in southeastern Asia. Added to the complex effects of clouds and natural marine aerosols, dust particles reaching the marine environment can have drastically different properties than those from the source. Thus, understanding the unique temporal and spatial variations of Asian aerosols is of special importance in regional-to-global climate issues such as radiative forcing, the hydrological cycle, and primary biological productivity in the mid-Pacific Ocean. During ACE-Asia we have measured continuously aerosol physical/optical/radiative properties, column precipitable water amount, and surface reflectivity over homogeneous areas from surface. The inclusion of flux measurements permits the determination of aerosol radiative flux in addition to measurements of loading and optical depth. At the time of the Terra/MODIS (Moderate Resolution Imaging Spectroradiometer), SeaWiFS (Sea-viewing Wide Field-of-view Sensor), TOMS (Total Ozone Mapping Spectrometer) and other satellite overpasses, these ground-based observations can provide valuable data to compare with satellite retrievals over land. A column satellite-surface perspective of Asian aerosols will be presented

  14. Effect of aerosols loading and retention on surface temperature in the DJF months

    Science.gov (United States)

    Emetere, M. E.; Onyechekwa, L.; Tunji-Olayeni, P.

    2017-05-01

    The effect of aerosols loading most often results in aerosols retention in the atmosphere. Aside the health hazards of aerosol retention, its effect on climate change are visible. In this research, it was proposed that the effect of aerosol retention also affects the fluctuation of the surface temperature. The location of study is Enugu, Nigeria (6.4584° N, 7.5464° E). Twenty-nine years GISS Surface Temperature Analysis (GISTEMP) data set and sixteen years MISR aerosol optical data set were used. The fluctuations in the sixteen years aerosol optical depth (AOD) tallied with the surface temperature. The curve-fitting tool of Matlab was used to generate a polynomial for the surface temperature and used to project a five years prediction of the surface temperature.

  15. Extinction efficiencies of coated absorbing aerosols measured by cavity ring down aerosol spectrometry

    Directory of Open Access Journals (Sweden)

    E. Segre

    2008-03-01

    Full Text Available In this study, we measure the extinction efficiency at 532 nm of absorbing aerosol particles coated with a non-absorbing solid and liquid organic shell with coating thickness varying between 5 and 100 nm using cavity ring down aerosol spectrometry. For this purpose, we use nigrosin, an organic black dye, as a model absorbing core and two non-absorbing organic substances as shells, glutaric acid (GA and Di-Ethyl-Hexyl-Sebacate (DEHS. The measured behavior of the coated particles is consistent with Mie calculations of core-shell particles. Errors between measured and calculated values for nigrosin coated with GA and DEHS are between 0.5% and 10.5% and between 0.5% and 9%, respectively. However, it is evident that the calculations are in better agreement with the measured results for thinner coatings. Possible reasons for these discrepancies are discussed.

  16. On the New Satellite Aerosol Measurements for Atmospheric Applications: VIIRS Aerosol Products

    Science.gov (United States)

    Huang, H.; Laszlo, I.; Kondragunta, S.; Liu, H.; Huang, J.; Cronk, H. Q.; Remer, L. A.; Sayer, A. M.

    2012-12-01

    The Joint Polar Satellite System (JPSS) is the USA's next generation polar-orbiting operational environmental satellite system. JPSS will provide operational continuity of satellite-based observations and products for the Suomi National Polar-orbiting Partnership (NPP) mission. JPSS/NPP will provide a continuation of major long-term observations by the Earth Observing System such as Terra, Aqua, and Aura to enhance our understanding of the climate change processes. Visible Infrared Imaging Radiometer Suite (VIIRS) is a multi-spectral scanning radiometer (22 bands between 0.4μm and 12μm) on-board JPSS/NPP with spatial resolution for 16 bands at 750m and 5 bands at 325m. The spatial resolution of Aerosol Optical Thickness (AOT) Environment Data Record (EDR) is 6 km at nadir compared to 10km at nadir for Moderate-Resolution Imaging Spectroradiometer (MODIS). Separate algorithms are used for aerosol retrieval over land and ocean. The over-land aerosol algorithm is based on MODIS surface Reflectance (MOD09 Collection 5) algorithm and the over-ocean algorithm is derived from the MODIS Aerosol (MOD04 Collection 5) algorithm. AOT and aerosol type are retrieved simultaneously by minimizing the difference between observed and calculated reflectance in multiple channels. VIIRS aerosol products include AOT, Aerosol Particle Size Parameter (APSP), and suspended matter. At the time of this presentation, the beta release of VIIRS aerosol data is expected to be available to the community to allow users to gain familiarity with data formats and parameters. The beta release of VIIRS aerosol products is expected to include AOT EDR of both over land and ocean and the APSP (Angstrom Exponent) EDR over ocean. To understand the present performance of VIIRS aerosol products at beta level and the difference of AOT retrievals between VIIRS and MODIS for long-term climatic applications, this study will focus on comparisons between VIIRS AOT and that of AErosol RObotic NETwork (AERONET

  17. Analysis of remotely sensed and surface data of aerosols and meteorology for the Mexico Megalopolis Area between 2003 and 2015

    Science.gov (United States)

    Mora, Marco; Braun, Rachel A.; Shingler, Taylor; Sorooshian, Armin

    2017-01-01

    This paper presents an aerosol characterization study from 2003 to 2015 for the Mexico City Metropolitan Area using remotely sensed aerosol data, ground-based measurements, air mass trajectory modeling, aerosol chemical composition modeling, and reanalysis data for the broader Megalopolis of Central Mexico region. The most extensive biomass burning emissions occur between March and May concurrent with the highest aerosol optical depth, ultraviolet aerosol index, and surface particulate matter (PM) mass concentration values. A notable enhancement in coarse PM levels is observed during vehicular rush hour periods on weekdays versus weekends owing to nonengine-related emissions such as resuspended dust. Among wet deposition species measured, PM2.5, PM10, and PMcoarse (PM10−PM2.5) were best correlated with NH4+, SO42−, and Ca2+, suggesting that the latter three constituents are important components of the aerosol seeding raindrops that eventually deposit to the surface in the study region. Reductions in surface PM mass concentrations were observed in 2014–2015 owing to reduced regional biomass burning as compared to 2003–2013. PMID:28955600

  18. Analysis of remotely sensed and surface data of aerosols and meteorology for the Mexico Megalopolis Area between 2003 and 2015.

    Science.gov (United States)

    Mora, Marco; Braun, Rachel A; Shingler, Taylor; Sorooshian, Armin

    2017-08-27

    This paper presents an aerosol characterization study from 2003 to 2015 for the Mexico City Metropolitan Area using remotely sensed aerosol data, ground-based measurements, air mass trajectory modeling, aerosol chemical composition modeling, and reanalysis data for the broader Megalopolis of Central Mexico region. The most extensive biomass burning emissions occur between March and May concurrent with the highest aerosol optical depth, ultraviolet aerosol index, and surface particulate matter (PM) mass concentration values. A notable enhancement in coarse PM levels is observed during vehicular rush hour periods on weekdays versus weekends owing to nonengine-related emissions such as resuspended dust. Among wet deposition species measured, PM 2.5 , PM 10 , and PM coarse (PM 10 -PM 2.5 ) were best correlated with NH 4 + , SO 4 2- , and Ca 2+ , suggesting that the latter three constituents are important components of the aerosol seeding raindrops that eventually deposit to the surface in the study region. Reductions in surface PM mass concentrations were observed in 2014-2015 owing to reduced regional biomass burning as compared to 2003-2013.

  19. Aerosol optical properties over the Svalbard region of Arctic: ground-based measurements and satellite remote sensing

    Science.gov (United States)

    Gogoi, Mukunda M.; Babu, S. Suresh

    2016-05-01

    In view of the increasing anthropogenic presence and influence of aerosols in the northern polar regions, long-term continuous measurements of aerosol optical parameters have been investigated over the Svalbard region of Norwegian Arctic (Ny-Ålesund, 79°N, 12°E, 8 m ASL). This study has shown a consistent enhancement in the aerosol scattering and absorption coefficients during spring. The relative dominance of absorbing aerosols is more near the surface (lower single scattering albedo), compared to that at the higher altitude. This is indicative of the presence of local anthropogenic activities. In addition, long-range transported biomass burning aerosols (inferred from the spectral variation of absorption coefficient) also contribute significantly to the higher aerosol absorption in the Arctic spring. Aerosol optical depth (AOD) estimates from ground based Microtop sun-photometer measurements reveals that the columnar abundance of aerosols reaches the peak during spring season. Comparison of AODs between ground based and satellite remote sensing indicates that deep blue algorithm of Moderate Resolution Imaging Spectroradiometer (MODIS) retrievals over Arctic snow surfaces overestimate the columnar AOD.

  20. Citizen-Enabled Aerosol Measurements for Satellites (CEAMS): A Network for High-Resolution Measurements of PM2.5 and Aerosol Optical Depth

    Science.gov (United States)

    Pierce, J. R.; Volckens, J.; Ford, B.; Jathar, S.; Long, M.; Quinn, C.; Van Zyl, L.; Wendt, E.

    2017-12-01

    Atmospheric particulate matter with diameter smaller than 2.5 μm (PM2.5) is a pollutant that contributes to the development of human disease. Satellite-derived estimates of surface-level PM2.5 concentrations have the potential to contribute greatly to our understanding of how particulate matter affects health globally. However, these satellite-derived PM2.5 estimates are often uncertain due to a lack of information about the ratio of surface PM2.5 to aerosol optical depth (AOD), which is the primary aerosol retrieval made by satellite instruments. While modelling and statistical analyses have improved estimates of PM2.5:AOD, large uncertainties remain in situations of high PM2.5 exposure (such as urban areas and in wildfire-smoke plumes) where the health impacts of PM2.5 may be the greatest. Surface monitoring networks for co-incident PM2.5 and AOD measurements are extremely rare, even in the North America. To provide constraints for the PM2.5:AOD relationship, we have developed a relatively low-cost (performed across 4 discrete wavelengths that match those reported by the Aerosol Robotic Network (AERONET). Aerosol concentration is reported using both time-integrated filter mass (analyzed in an academic laboratory and reported as a 24-48hr average) and a continuous PM sensor within the instrument. Citizen scientists use the device to report daily AOD and PM2.5 measurements made in their backyards to a central server for data display and download. In this presentation, we provide an overview of (1) AOD and PM2.5 measurement calibration; (2) citizen recruiting and training efforts; and (3) results from our pilot citizen-science measurement campaign.

  1. Aerosol direct effect on solar radiation over the eastern Mediterranean Sea based on AVHRR satellite measurements

    Science.gov (United States)

    Georgakaki, Paraskevi; Papadimas, Christos D.; Hatzianastassiou, Nikos; Fotiadi, Aggeliki; Matsoukas, Christos; Stackhouse, Paul; Kanakidou, Maria; Vardavas, Ilias M.

    2017-04-01

    Despite the improved scientific understanding of the direct effect of aerosols on solar radiation (direct radiative effect, DRE) improvements are necessary, for example regarding the accuracy of the magnitude of estimated DREs and their spatial and temporal variability. This variability cannot be ensured by in-situ surface and airborne measurements, while it is also relatively difficult to capture through satellite observations. This becomes even more difficult when complete spatial coverage of extended areas is required, especially concerning areas that host various aerosol types with variable physico-chemical and optical aerosol properties. Better assessments of aerosol DREs are necessary, relying on aerosol optical properties with high spatial and temporal variation. The present study aims to provide a refined, along these lines, assessment of aerosol DREs over the eastern Mediterranean (EM) Sea, which is a key area for aerosol studies. Daily DREs are computed for 1˚ x1˚ latitude-longitude grids with the FORTH detailed spectral radiation transfer model (RTM) using input data for various atmospheric and surface parameters, such as clouds, water vapor, ozone and surface albedo, taken from the NASA-Langley Global Earth Observing System (GEOS) database. The model spectral aerosol optical depth (AOD), single scattering albedo and asymmetry parameter are taken from the Global Aerosol Data Set and the NOAA Climate Data Record (CDR) version 2 of Advanced Very High resolution Radiometer (AVHRR) AOD dataset which is available over oceans at 0.63 microns and at 0.1˚ x0.1˚ . The aerosol DREs are computed at the surface, the top-of-atmosphere and within the atmosphere, over the period 1985-1995. Preliminary model results for the period 1990-1993 reveal a significant spatial and temporal variability of DREs over the EM Sea, for example larger values over the Aegean and Black Seas, surrounded by land areas with significant anthropogenic aerosol sources, and over the

  2. Influence of aerosol and surface reflectance variability on hyperspectral observed radiance

    Directory of Open Access Journals (Sweden)

    C. Bassani

    2012-06-01

    Full Text Available Current aerosol retrievals based on visible and near infrared remote-sensing, are prone to loss of accuracy, where the assumptions of the applied algorithm are violated. This happens mostly over land and it is related to misrepresentation of specific aerosol conditions or surface properties. New satellite missions, based on high spectral resolution instruments, such as PRISMA (Hyperspectral Precursor of the Application Mission, represent a valuable opportunity to improve the accuracy of τa550 retrievable from a remote-sensing system developing new atmospheric measurement techniques. This paper aims to address the potential of these new observing systems in more accurate retrieving τa550, specifically over land in heterogeneous and/or homogeneous areas composed by dark and bright targets. The study shows how the variation of the hyperspectral observed radiance can be addressed to recognise a variation of Δτa550 = 0.02. The goal has been achieved by using simulated radiances by combining two aerosol models (urban and continental and two reflecting surfaces: dark (represented by water and bright (represented by sand for the PRISMA instrument, considering the environmental contribution of the observed radiance, i.e., the adjacency effect. Results showed that, in the continental regime, the expected instrument sensitivity would allow for retrieval accuracy of the aerosol optical thickness at 550 nm of 0.02 or better, with a dark surface surrounded by dark areas. The study also showed that for the urban regime, the surface plays a more significant role, with a bright surface surrounded by dark areas providing favourable conditions for the aerosol load retrievals, and dark surfaces representing less suitable situations for inversion independently of the surroundings. However, over all, the results obtained provide evidence that high resolution observations of Earth spectrum between

  3. Characteristics, sources, and transport of aerosols measured in spring 2008 during the aerosol, radiation, and cloud processes affecting Arctic Climate (ARCPAC Project

    Directory of Open Access Journals (Sweden)

    C. A. Brock

    2011-03-01

    Full Text Available We present an overview of the background, scientific goals, and execution of the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC project of April 2008. We then summarize airborne measurements, made in the troposphere of the Alaskan Arctic, of aerosol particle size distributions, composition, and optical properties and discuss the sources and transport of the aerosols. The aerosol data were grouped into four categories based on gas-phase composition. First, the background troposphere contained a relatively diffuse, sulfate-rich aerosol extending from the top of the sea-ice inversion layer to 7.4 km altitude. Second, a region of depleted (relative to the background aerosol was present within the surface inversion layer over sea-ice. Third, layers of dense, organic-rich smoke from open biomass fires in southern Russia and southeastern Siberia were frequently encountered at all altitudes from the top of the inversion layer to 7.1 km. Finally, some aerosol layers were dominated by components originating from fossil fuel combustion.

    Of these four categories measured during ARCPAC, the diffuse background aerosol was most similar to the average springtime aerosol properties observed at a long-term monitoring site at Barrow, Alaska. The biomass burning (BB and fossil fuel layers were present above the sea-ice inversion layer and did not reach the sea-ice surface during the course of the ARCPAC measurements. The BB aerosol layers were highly scattering and were moderately hygroscopic. On average, the layers produced a noontime net heating of ~0.1 K day−1 between 3 and 7 km and a slight cooling at the surface. The ratios of particle mass to carbon monoxide (CO in the BB plumes, which had been transported over distances >5000 km, were comparable to the high end of literature values derived from previous measurements in wildfire smoke. These ratios suggest minimal precipitation scavenging and removal of the BB

  4. Two-Column Aerosol Project: Aerosol Light Extinction Measurements Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Dubey, Manvendra [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aiken, Allison [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Berg, Larry K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Freedman, Andrew [Aerodyne Research, Inc., Billerica, MA (United States); Gorkowski, Kyle [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-01

    We deployed Aerodyne Research Inc.’s first Cavity Attenuated Phase Shift extinction (CAPS PMex) monitor (built by Aerodyne) that measures light extinction by using a visible-light-emitting diode (LED) as a light source, a sample cell incorporating two high-reflectivity mirrors centered at the wavelength of the LED, and a vacuum photodiode detector in Cape Cod in 2012/13 for the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility’s Two-Column Aerosol Project (TCAP). The efficacy of this instrument is based on the fact that aerosols are broadband scatterers and absorbers of light. The input LED is square-wave modulated and passed through the sample cell that distorts it due to exponential decay by aerosol light absorption and scattering; this is measured at the detector. The amount of phase shift of the light at the detector is used to determine the light extinction. This extinction measurement provides an absolute value, requiring no calibration. The goal was to compare the CAPS performance with direct measurements of absorption with ARM’s baseline photoacoustic soot spectrometer (PASS-3) and nephelometer instruments to evaluate its performance.

  5. Airborne measurements of submicron aerosols across the coastline ...

    Indian Academy of Sciences (India)

    3080, of TSI, installed onboard a beachcraft air- craft is used to make measurements of the number concentration and size distribution of aerosol par- ticles in the size range of 13 to 700nm. The air sample is taken through an air inlet fixed at the belly of the aircraft and is located ~2 m away from the nose of the aircraft.

  6. Portable diffusion battery. It's application to measuring aerosol size characteristics

    International Nuclear Information System (INIS)

    Sinclair, D.

    1972-01-01

    A miniature portable cluster-tube diffusion battery for measurement of the size and size distribution of submicron aerosols (1-100 nm) is described. A series of commercially available Collimated Holes Structures are mounted in sleeves with O-rings so that aerosol penetration can be measured at a number of outlets along the series. The CHS are stainless-steel discs of several different diameters and thicknesses, containing a large number of nearly circular holes. The actual length of the apparatus is about 2 ft but the equivalent length is 3.25 mi. Calculated curves of penetration versus particle size are used to evaluate size distribution and show that the equivalent size frequently reported from one measurement with a rectangular diffusion battery is practically meaningless. The value depends as much on the characteristics and mode of the operation of the diffusion battery as on the aerosol; the longer the battery and the lower the air flow, the greater the equivalent size will appear to be. Graphical plots of the cumulative size distribution of room aerosol and silver aerosol are illustrated for large battery and miniature battery measurements and appear to be in close agreement. Measurements on radon daughters in uranium mines with the miniature batteries show activity median diameters from 0.1 to 0.17 micron, with standard deviations from 2 to 4. Two similar measurements made in the laboratory on room air tagged with about 50 pCi/l radon daughters show activity median diameters of 0.15 and 0.17 micron, with geometric standard deviations of 2.2 and 2.6, respectively

  7. Measurement of aerosol sulfuric acid 2. Pronounced layering in the free troposphere during the second Aerosol Characterization Experiment (ACE 2)

    NARCIS (Netherlands)

    Curtius, J; Sierau, B; Arnold, F; de Reus, M; Strom, J; Scheeren, HA; Lelieveld, J

    2001-01-01

    Measurements of aerosol sulfuric acid in the free troposphere were performed in the vicinity of Tenerife, Canary Islands (28degreesN, 16degreesW), in July 1997. These measurements were carried out on board a Dutch Cessna Citation 11 research aircraft within the framework of the second Aerosol

  8. Improving Satellite Retrieved Infrared Sea Surface Temperatures in Aerosol-Contaminated Regions

    Science.gov (United States)

    Luo, B.; Minnett, P. J.; Szczodrak, G.; Kilpatrick, K. A.

    2017-12-01

    Infrared satellite observations of sea surface temperature (SST) have become essential for many applications in meteorology, climatology, and oceanography. Applications often require high accuracy SST data: for climate research and monitoring an absolute uncertainty of 0.1K and stability of better than 0.04K per decade are required. Tropospheric aerosol concentrations increase infrared signal attenuation and prevent the retrieval of accurate satellite SST. We compare satellite-derived skin SST with measurements from the Marine-Atmospheric Emitted Radiance Interferometer (M-AERI) deployed on ships during the Aerosols and Ocean Science Expeditions (AEROSE) and with quality-controlled drifter temperatures. After match-up with in-situ SST and filtering of cloud contaminated data, the results indicate that SST retrieved from MODIS (Moderate Resolution Imaging Spectroradiometer) aboard the Terra and Aqua satellites have negative (cool) biases compared to shipboard radiometric measurements. There is also a pronounced negative bias in the Saharan outflow area that can introduce SST errors >1 K at aerosol optical depths > 0.5. In this study, we present a new method to derive night-time Saharan Dust Index (SDI) algorithms based on simulated brightness temperatures at infrared wavelengths of 3.9, 10.8 and 12.0 μm, derived using RTTOV. We derived correction coefficients for Aqua MODIS measurements by regression of the SST errors against the SDI. The biases and standard deviations are reduced by 0.25K and 0.19K after the SDI correction. The goal of this study is to understand better the characteristics and physical mechanisms of aerosol effects on satellite retrieved infrared SST, as well as to derive empirical formulae for improved accuracies in aerosol-contaminated regions.

  9. Modeling South America regional smoke plume: aerosol optical depth variability and shortwave surface forcing

    Science.gov (United States)

    Rosário, N. E.; Longo, K. M.; Freitas, S. R.; Yamasoe, M. A.; Fonseca, R. M.

    2012-07-01

    Intra-seasonal variability of smoke aerosol optical depth (AOD) and downwelling solar irradiance at the surface during the 2002 biomass burning season in South America was modeled using the Coupled Chemistry-Aerosol-Tracer Transport model to the Brazilian developments on the Regional Atmospheric Modeling System (CCATT-BRAMS). Measurements of AOD from the AErosol RObotic NETwork (AERONET) and solar irradiance at the surface from the Solar Radiation Network (SolRad-NET) were used to evaluate model results. In general, the major features associated with AOD evolution over the southern part of the Amazon Basin and cerrado ecosystem are captured by the model. The main discrepancies were found for high aerosol loading events. In the northeastern portion of the Amazon Basin the model systematically underestimated AOD. This is likely due to the cloudy nature of the region, preventing accurate detection of the fire spots used in the emission model. Moreover, measured AOD were very often close to background conditions and emissions other than smoke were not considered in the simulation. Therefore, under the background scenario, one would expect the model to underestimate AOD. The issue of high aerosol loading events in the southern part of the Amazon and cerrado is also discussed in the context of emission shortcomings. The Cuiabá cerrado site was the only one where the highest quality AERONET data were unavailable. Thus, lower quality data were used. Root-mean-square-error (RMSE) between the model and observations decreased from 0.48 to 0.17 when extreme AOD events (AOD550 nm ≥ 1.0) and Cuiabá were excluded from analysis. Downward surface solar irradiance comparisons also followed similar trends when extremes AOD were excluded. This highlights the need to improve the modelling of the regional smoke plume in order to enhance the accuracy of the radiative energy budget. Aerosol optical model based on the mean intensive properties of smoke from the southern part of the

  10. Do organic surface films on sea salt aerosols influence atmospheric chemistry? ─ a model study

    Directory of Open Access Journals (Sweden)

    R. von Glasow

    2007-11-01

    Full Text Available Organic material from the ocean's surface can be incorporated into sea salt aerosol particles often producing a surface film on the aerosol. Such an organic coating can reduce the mass transfer between the gas phase and the aerosol phase influencing sea salt chemistry in the marine atmosphere. To investigate these effects and their importance for the marine boundary layer (MBL we used the one-dimensional numerical model MISTRA. We considered the uncertainties regarding the magnitude of uptake reduction, the concentrations of organic compounds in sea salt aerosols and the oxidation rate of the organics to analyse the possible influence of organic surfactants on gas and liquid phase chemistry with a special focus on halogen chemistry. By assuming destruction rates for the organic coating based on laboratory measurements we get a rapid destruction of the organic monolayer within the first meters of the MBL. Larger organic initial concentrations lead to a longer lifetime of the coating but lead also to an unrealistically strong decrease of O3 concentrations as the organic film is destroyed by reaction with O3. The lifetime of the film is increased by assuming smaller reactive uptake coefficients for O3 or by assuming that a part of the organic surfactants react with OH. With regard to tropospheric chemistry we found that gas phase concentrations for chlorine and bromine species decreased due to the decreased mass transfer between gas phase and aerosol phase. Aqueous phase chlorine concentrations also decreased but aqueous phase bromine concentrations increased. Differences for gas phase concentrations are in general smaller than for liquid phase concentrations. The effect on gas phase NO2 or NO is very small (reduction less than 5% whereas liquid phase NO2 concentrations increased in some cases by nearly 100%. We list suggestions for further laboratory studies which are needed for improved model studies.

  11. A sea surface reflectance model for (A)ATSR, and application to aerosol retrievals

    Science.gov (United States)

    Sayer, A. M.; Thomas, G. E.; Grainger, R. G.

    2010-07-01

    A model of the sea surface bidirectional reflectance distribution function (BRDF) is presented for the visible and near-IR channels (over the spectral range 550 nm to 1.6 μm) of the dual-viewing Along-Track Scanning Radiometers (ATSRs). The intended application is as part of the Oxford-RAL Aerosols and Clouds (ORAC) retrieval scheme. The model accounts for contributions to the observed reflectance from whitecaps, sun-glint and underlight. Uncertainties in the parametrisations used in the BRDF model are propagated through into the forward model and retrieved state. The new BRDF model offers improved coverage over previous methods, as retrievals are possible into the sun-glint region, through the ATSR dual-viewing system. The new model has been applied in the ORAC aerosol retrieval algorithm to process Advanced ATSR (AATSR) data from September 2004 over the south-eastern Pacific. The assumed error budget is shown to be generally appropriate, meaning the retrieved states are consistent with the measurements and a priori assumptions. The resulting field of aerosol optical depth (AOD) is compared with colocated MODIS-Terra observations, AERONET observations at Tahiti, and cruises over the oceanic region. MODIS and AATSR show similar spatial distributions of AOD, although MODIS reports values which are larger and more variable. It is suggested that assumptions in the MODIS aerosol retrieval algorithm may lead to a positive bias in MODIS AOD of order 0.01 at 550 nm over ocean regions where the wind speed is high.

  12. Time Resolved Measurements of Primary Biogenic Aerosol Particles in Amazonia

    Science.gov (United States)

    Wollny, A. G.; Garland, R.; Pöschl, U.

    2009-04-01

    Biogenic aerosols are ubiquitous in the Earth's atmosphere and they influence atmospheric chemistry and physics, the biosphere, climate, and public health. They play an important role in the spread of biological organisms and reproductive materials, and they can cause or enhance human, animal, and plant diseases. Moreover, they influence the Earth's energy budget by scattering and absorbing radiation, and they can initiate the formation of clouds and precipitation as cloud condensation and ice nuclei. The composition, abundance, and origin of biogenic aerosol particles and components are, however, still not well understood and poorly quantified. Prominent examples of primary biogenic aerosol particles, which are directly emitted from the biosphere to the atmosphere, are pollen, bacteria, fungal spores, viruses, and fragments of animals and plants. During the Amazonian Aerosol Characterization Experiment (AMAZE-08) a large number of aerosol and gas-phase measurements were taken on a remote site close to Manaus, Brazil, during a period of five weeks in February and March 2008. This presented study is focused on data from an ultraviolet aerodynamic particle sizer (UVAPS, TSI inc.) that has been deployed for the first time in Amazonia. In this instrument, particle counting and aerodynamic sizing over the range of 0.5-20 µm are complemented by the measurement of UV fluorescence at 355 nm (excitation) and 420-575 nm (emission), respectively. Fluorescence at these wavelengths is characteristic for reduced pyridine nucleotides (e.g., NAD(P)H) and for riboflavin, which are specific for living cells. Thus particles exhibiting fluorescence signals can be regarded as "viable aerosols" or "fluorescent bioparticles" (FBAP), and their concentration can be considered as lower limit for the actual abundance of primary biogenic aerosol particles. Data from the UVAPS were averaged over 5 minute time intervals. The presence of bioparticles in the observed size range has been

  13. Probing into the aging dynamics of biomass burning aerosol by using satellite measurements of aerosol optical depth and carbon monoxide

    Science.gov (United States)

    Konovalov, Igor B.; Beekmann, Matthias; Berezin, Evgeny V.; Formenti, Paola; Andreae, Meinrat O.

    2017-04-01

    Carbonaceous aerosol released into the atmosphere from open biomass burning (BB) is known to undergo considerable chemical and physical transformations (aging). However, there is substantial controversy about the nature and observable effects of these transformations. A shortage of consistent observational evidence on BB aerosol aging processes under different environmental conditions and at various temporal scales hinders development of their adequate representations in chemistry transport models (CTMs). In this study, we obtain insights into the BB aerosol dynamics by using available satellite measurements of aerosol optical depth (AOD) and carbon monoxide (CO). The basic concept of our method is to consider AOD as a function of the BB aerosol photochemical age (that is, the time period characterizing the exposure of BB aerosol emissions to atmospheric oxidation reactions) predicted by means of model tracers. We evaluate the AOD enhancement ratio (ER) defined as the ratio of optical depth of actual BB aerosol with respect to that of a modeled aerosol tracer that is assumed to originate from the same fires as the real BB aerosol but that is not affected by any aging processes. To limit possible effects of model transport errors, the AOD measurements are normalized to CO column amounts that are also retrieved from satellite measurements. The method is applied to the analysis of the meso- and synoptic-scale evolution of aerosol in smoke plumes from major wildfires that occurred in Siberia in summer 2012. AOD and CO retrievals from MODIS and IASI measurements, respectively, are used in combination with simulations performed with the CHIMERE CTM. The analysis indicates that aging processes strongly affected the evolution of BB aerosol in the situation considered, especially in dense plumes (with spatial average PM2. 5 concentration exceeding 100 µg m-3). For such plumes, the ER is found to increase almost 2-fold on the scale of ˜ 10 h of daytime aerosol evolution

  14. Long-term analysis of aerosol optical depth over Northeast Asia using a satellite-based measurement: MI Yonsei Aerosol Retrieval Algorithm (YAER)

    Science.gov (United States)

    Kim, Mijin; Kim, Jhoon; Yoon, Jongmin; Chung, Chu-Yong; Chung, Sung-Rae

    2017-04-01

    In 2010, the Korean geostationary earth orbit (GEO) satellite, the Communication, Ocean, and Meteorological Satellite (COMS), was launched including the Meteorological Imager (MI). The MI measures atmospheric condition over Northeast Asia (NEA) using a single visible channel centered at 0.675 μm and four IR channels at 3.75, 6.75, 10.8, 12.0 μm. The visible measurement can also be utilized for the retrieval of aerosol optical properties (AOPs). Since the GEO satellite measurement has an advantage for continuous monitoring of AOPs, we can analyze the spatiotemporal variation of the aerosol using the MI observations over NEA. Therefore, we developed an algorithm to retrieve aerosol optical depth (AOD) using the visible observation of MI, and named as MI Yonsei Aerosol Retrieval Algorithm (YAER). In this study, we investigated the accuracy of MI YAER AOD by comparing the values with the long-term products of AERONET sun-photometer. The result showed that the MI AODs were significantly overestimated than the AERONET values over bright surface in low AOD case. Because the MI visible channel centered at red color range, contribution of aerosol signal to the measured reflectance is relatively lower than the surface contribution. Therefore, the AOD error in low AOD case over bright surface can be a fundamental limitation of the algorithm. Meanwhile, an assumption of background aerosol optical depth (BAOD) could result in the retrieval uncertainty, also. To estimate the surface reflectance by considering polluted air condition over the NEA, we estimated the BAOD from the MODIS dark target (DT) aerosol products by pixel. The satellite-based AOD retrieval, however, largely depends on the accuracy of the surface reflectance estimation especially in low AOD case, and thus, the BAOD could include the uncertainty in surface reflectance estimation of the satellite-based retrieval. Therefore, we re-estimated the BAOD using the ground-based sun-photometer measurement, and

  15. Combining Airborne and Lidar Measurements for Attribution of Aerosol Layers

    Science.gov (United States)

    Nikandrova, A.; Väänänen, R.; Tabakova, K.; Kerminen, V. M.; O'Connor, E.

    2016-12-01

    The aim of this work was to identify discrete aerosol layers and diagnose their origin, investigate the strength of mixing within the free-troposphere and with the boundary layer (BL), and understand the impact that mixing has on local and long-range transport of aerosol. For these purposes we combined airborne in-situ aerosol measurements with data obtained by a High Spectral Resolution Lidar (HSRL). The HSRL was deployed in Hyytiälä, Southern Finland, from January to September 2014 as a part of the US DoE ARM (Atmospheric Radiation Measurement) Mobile Facility during the BAECC (Biogenic Aerosols - Effects on Cloud and Climate) Campaign. Two airborne campaigns took place in April and August 2014 during the BAECC campaign. The vertical profile of backscatter coefficient from the HSRL was used to diagnose the location and depth of significant aerosol layers in the atmosphere. Frequently, in addition to the BL, one or two tropospheric layers were identified. In-situ measurements of the aerosol size distribution in these layers were obtained from a Scanning Mobility Particle Sizer (SMPS) and Optical Particle Sizer (OPS), that were installed on board the aircraft; these measurements were combined to cover sizes ranging from 10 nm to 10 µm. As expected, the highest number concentration of aerosol particles at all size ranges was found predominantly in the BL. Many upper layers had size distributions with a similar shape to that in the BL but with overall lower concentrations attributed to dilution of particles into a large volume of air. Hence, these layers were likely of very similar origin to the air in the BL and presumably were the result of lofted residual layers. Intervening layers however, could contain markedly different distribution shapes, which could be attributed to both different air mass origins, and different ambient relative humidity. Potential for mixing between two discreet elevated layers was often seen as a thin interface layer, which exhibited a

  16. Eddy Covariance Measurements of the Sea-Spray Aerosol Flu

    Science.gov (United States)

    Brooks, I. M.; Norris, S. J.; Yelland, M. J.; Pascal, R. W.; Prytherch, J.

    2015-12-01

    Historically, almost all estimates of the sea-spray aerosol source flux have been inferred through various indirect methods. Direct estimates via eddy covariance have been attempted by only a handful of studies, most of which measured only the total number flux, or achieved rather coarse size segregation. Applying eddy covariance to the measurement of sea-spray fluxes is challenging: most instrumentation must be located in a laboratory space requiring long sample lines to an inlet collocated with a sonic anemometer; however, larger particles are easily lost to the walls of the sample line. Marine particle concentrations are generally low, requiring a high sample volume to achieve adequate statistics. The highly hygroscopic nature of sea salt means particles change size rapidly with fluctuations in relative humidity; this introduces an apparent bias in flux measurements if particles are sized at ambient humidity. The Compact Lightweight Aerosol Spectrometer Probe (CLASP) was developed specifically to make high rate measurements of aerosol size distributions for use in eddy covariance measurements, and the instrument and data processing and analysis techniques have been refined over the course of several projects. Here we will review some of the issues and limitations related to making eddy covariance measurements of the sea spray source flux over the open ocean, summarise some key results from the last decade, and present new results from a 3-year long ship-based measurement campaign as part of the WAGES project. Finally we will consider requirements for future progress.

  17. Development and validation of a CCD-laser aerosol detective system for measuring the ambient aerosol phase function

    Science.gov (United States)

    Bian, Yuxuan; Zhao, Chunsheng; Xu, Wanyun; Zhao, Gang; Tao, Jiangchuan; Kuang, Ye

    2017-06-01

    Aerosol phase function represents the angular scattering property of aerosols, which is crucial for understanding the climate effects of aerosols that have been identified as one of the largest uncertainties in the evaluation of radiative forcing. So far, there is a lack of instruments with which to measure the aerosol phase function directly and accurately in laboratory studies and in situ measurements. A portable instrument with high angular range and resolution has been developed for the measurement of the phase function of ambient aerosols in this study. The charge-coupled device-laser aerosol detective system (CCD-LADS) measures the aerosol phase function both across a relatively wide angular range of 10-170° and at a high resolution of 0.1°. The system includes a continuous laser, two charge-coupled device cameras and the corresponding fisheye lenses. The CCD-LADS was validated by both a laboratory study and a field measurement. The comparison between the aerosol phase function retrieved from CCD-LADS and Mie-scattering model shows good agreement. Compared with the TSI polar nephelometer, CCD-LADS has the advantages of wider detection range and better stability.

  18. Online high sensitivity measurement system for transuranic aerosols

    International Nuclear Information System (INIS)

    Kordas, J.F.; Phelps, P.L.

    1976-01-01

    A measurement system for transuranic aerosols has been designed that will be able to withstand the corrosive nature of stack effluents and yet have extremely high sensitivity. It will be capable of measuring 1 maximum permissible concentration (MPC) of plutonium or americium in 30 minutes with a fractional standard deviation of less than 0.33. Background resulting from 218 Po is eliminated by alpha energy discrimination and a decay scheme analysis. A microprocessor controls all data acquisition, data reduction, and instrument calibration

  19. Aerosol properties and their impacts on surface CCN at the ARM Southern Great Plains site during the 2011 Midlatitude Continental Convective Clouds Experiment

    Science.gov (United States)

    Logan, Timothy; Dong, Xiquan; Xi, Baike

    2018-02-01

    Aerosol particles are of particular importance because of their impacts on cloud development and precipitation processes over land and ocean. Aerosol properties as well as meteorological observations from the Department of Energy Atmospheric Radiation Measurement (ARM) platform situated in the Southern Great Plains (SGP) are utilized in this study to illustrate the dependence of continental cloud condensation nuclei (CCN) number concentration ( N CCN) on aerosol type and transport pathways. ARM-SGP observations from the 2011 Midlatitude Continental Convective Clouds Experiment field campaign are presented in this study and compared with our previous work during the 2009-10 Clouds, Aerosol, and Precipitation in the Marine Boundary Layer field campaign over the current ARM Eastern North Atlantic site. Northerly winds over the SGP reflect clean, continental conditions with aerosol scattering coefficient ( σ sp) values less than 20 Mm-1 and N CCN values less than 100 cm-3. However, southerly winds over the SGP are responsible for the observed moderate to high correlation ( R) among aerosol loading ( σ sp moisture via the Gulf of Mexico, indicating a strong dependence on air mass type. NASA MERRA-2 reanalysis aerosol and chemical data are moderately to highly correlated with surface ARM-SGP data, suggesting that this facility can represent surface aerosol conditions in the SGP, especially during strong aerosol loading events that transport via the Gulf of Mexico. Future long-term investigations will help to understand the seasonal influences of air masses on aerosol, CCN, and cloud properties over land in comparison to over ocean.

  20. Aerosol measurement: principles, techniques, and applications

    National Research Council Canada - National Science Library

    Baron, Paul A; Kulkarni, Pramod; Willeke, Klaus

    2011-01-01

    ... to the state-of-the-art instruments that can perform nearinstantaneous size and chemical composition measurements, the advances are indeed exciting and promising with wide implications for public health and environmental protection, climate research, medicine, and industrial technology. Until the late 1980s, the development of new measurement method...

  1. Aerosol variability over the Mediterranean basin from 2005-2012 POLDER-3/PARASOL and AERONET/PHOTONS measurements

    Science.gov (United States)

    Chiapello, Isabelle; Ducos, Fabrice; Dulac, François; Léon, Jean-François; Mallet, Marc; Tanré, Didier; Goloub, Philippe

    2013-04-01

    POLDER-3 (Polarization and Directionnality of the Earth's Reflectances) has been launched on board the PARASOL microsatellite in December 2004. Although the PARASOL orbit has been lowered twice (in September 2009 and in November 2011) compared to the other platforms of the A-Train constellation, POLDER observations continue, providing now more than seven years of innovative retrievals of aerosol properties from space. In this study we focus on analyzing POLDER-3 capabilities to derive both aerosol loads (Total Aerosol Optical Thickness) and size properties (fine and coarse spherical/non-spherical Aerosol Optical Thickness, Angström coefficients) over oceanic surfaces. This analysis, as part of the ChArMEx (the Chemistry-Aerosol Mediterranean Experiment) program, focus on the Mediterranean basin, a region under the influence of a complex mixture of aerosols from different sources. Especially we aim to investigate the respective contributions of (i) pollution aerosols (emitted by industry and urban environments of some European regions or megacities surrounding the basin), (ii) carbonaceous particles (from biomass burning events), (iii) mineral dust exported from arid and semi-arid regions of North Africa. In a first step, our study consists in an analysis of aerosol variability retrieved from AERONET/PHOTONS photometer records from selected sites located in Western part of the Mediterranean basin (i.e., Soust-East of France, Spain, Corsica/Sardinia), as well as central part (i.e., Italia and Lampedusa), and Eastern part (i.e.,Greece and Turkey). These measurements provide a unique characterization of both aerosol load (aerosol optical depth) and properties (size distribution and absorption though single scattering albedo) and their temporal variability over each part of the Mediterranean basin. The second step focus on a regional validation of the PARASOL monthly aerosol products by comparison with these equivalent and selected ground-based AERONET

  2. Light source effects on aerosol photoacoustic spectroscopy measurements

    Science.gov (United States)

    Radney, James G.; Zangmeister, Christopher D.

    2017-01-01

    Photoacoustic spectroscopy measurements of flame-generated soot aerosol coated with small amounts of water yielded absorption enhancements that were dependent on the laser used: quasi-continuous wave (Q-CW, ≈650 ps pulse duration and 78 MHz repetition rate) versus continuous wave (CW). Water coating thickness was controlled by exposing the aerosol to a set relative humidity (RH). At ≈85% RH, the mass of the soot particles increased by an amount comparable to a monolayer of water being deposited and enhanced the measured absorption by 36% and 15% for the Q-CW and CW lasers, respectively. Extinction measurements were also performed using a cavity ring-down spectrometer (extinction equals the sum of absorption and scattering) with a CW laser and negligible enhancement was observed at all RH. These findings demonstrate that source choice can impact measurements of aerosols with volatile coatings and that the absorption enhancements at high RH previously measured by Radney and Zangmeister [1] are the result of laser source used (Q-CW) and not from an increase in the particle absorption cross section.

  3. Effect of aerosols and NO2 concentration on ultraviolet actinic flux near Mexico City during MILAGRO: measurements and model calculations

    Directory of Open Access Journals (Sweden)

    C. A. Corr

    2013-01-01

    Full Text Available Urban air pollution absorbs and scatters solar ultraviolet (UV radiation, and thus has a potentially large effect on tropospheric photochemical rates. We present the first detailed comparison between actinic fluxes (AF in the wavelength range 330–420 nm measured in highly polluted conditions and simulated with the Tropospheric Ultraviolet-Visible (TUV model. Measurements were made during the MILAGRO campaign near Mexico City in March 2006, at a ground-based station near Mexico City (the T1 supersite and from the NSF/NCAR C-130 aircraft. At the surface, measured AF values are typically smaller than the model by up to 25% in the morning, 10% at noon, and 40% in the afternoon, for pollution-free and cloud-free conditions. When measurements of PBL height, NO2 concentration and aerosols optical properties are included in the model, the agreement improves to within ±10% in the morning and afternoon, and ±3% at noon. Based on daily averages, aerosols account for 68% and NO2 for 25% of AF reductions observed at the surface. Several overpasses from the C-130 aircraft provided the opportunity to examine the AF perturbations aloft, and also show better agreement with the model when aerosol and NO2 effects are included above and below the flight altitude. TUV model simulations show that the vertical structure of the actinic flux is sensitive to the choice of the aerosol single scattering albedo (SSA at UV wavelengths. Typically, aerosols enhance AF above the PBL and reduce AF near the surface. However, for highly scattering aerosols (SSA > 0.95, enhancements can penetrate well into the PBL, while for strongly absorbing aerosols (SSA < 0.6 reductions in AF are computed in the free troposphere as well as in the PBL. Additional measurements of the SSA at these wavelengths are needed to better constrain the effect of aerosols on the vertical structure of the AF.

  4. Effect of aerosols and NO2 concentration on ultraviolet actinic flux near Mexico City during MILAGRO: measurements and model calculations

    Science.gov (United States)

    Palancar, G. G.; Lefer, B. L.; Hall, S. R.; Shaw, W. J.; Corr, C. A.; Herndon, S. C.; Slusser, J. R.; Madronich, S.

    2013-01-01

    Urban air pollution absorbs and scatters solar ultraviolet (UV) radiation, and thus has a potentially large effect on tropospheric photochemical rates. We present the first detailed comparison between actinic fluxes (AF) in the wavelength range 330-420 nm measured in highly polluted conditions and simulated with the Tropospheric Ultraviolet-Visible (TUV) model. Measurements were made during the MILAGRO campaign near Mexico City in March 2006, at a ground-based station near Mexico City (the T1 supersite) and from the NSF/NCAR C-130 aircraft. At the surface, measured AF values are typically smaller than the model by up to 25% in the morning, 10% at noon, and 40% in the afternoon, for pollution-free and cloud-free conditions. When measurements of PBL height, NO2 concentration and aerosols optical properties are included in the model, the agreement improves to within ±10% in the morning and afternoon, and ±3% at noon. Based on daily averages, aerosols account for 68% and NO2 for 25% of AF reductions observed at the surface. Several overpasses from the C-130 aircraft provided the opportunity to examine the AF perturbations aloft, and also show better agreement with the model when aerosol and NO2 effects are included above and below the flight altitude. TUV model simulations show that the vertical structure of the actinic flux is sensitive to the choice of the aerosol single scattering albedo (SSA) at UV wavelengths. Typically, aerosols enhance AF above the PBL and reduce AF near the surface. However, for highly scattering aerosols (SSA > 0.95), enhancements can penetrate well into the PBL, while for strongly absorbing aerosols (SSA < 0.6) reductions in AF are computed in the free troposphere as well as in the PBL. Additional measurements of the SSA at these wavelengths are needed to better constrain the effect of aerosols on the vertical structure of the AF.

  5. Estimation of atmospheric columnar organic matter (OM) mass concentration from remote sensing measurements of aerosol spectral refractive indices

    Science.gov (United States)

    Zhang, Ying; Li, Zhengqiang; Sun, Yele; Lv, Yang; Xie, Yisong

    2018-04-01

    Aerosols have adverse effects on human health and air quality, changing Earth's energy balance and lead to climate change. The components of aerosol are important because of the different spectral characteristics. Based on the low hygroscopic and high scattering properties of organic matter (OM) in fine modal atmospheric aerosols, we develop an inversion algorithm using remote sensing to obtain aerosol components including black carbon (BC), organic matter (OM), ammonium nitrate-like (AN), dust-like (DU) components and aerosol water content (AW). In the algorithm, the microphysical characteristics (i.e. volume distribution and complex refractive index) of particulates are preliminarily separated to fine and coarse modes, and then aerosol components are retrieved using bimodal parameters. We execute the algorithm using remote sensing measurements of sun-sky radiometer at AERONET site (Beijing RADI) in a period from October of 2014 to January of 2015. The results show a reasonable distribution of aerosol components and a good fit for spectral feature calculations. The mean OM mass concentration in atmospheric column is account for 14.93% of the total and 56.34% of dry and fine-mode aerosol, being a fairly good correlation (R = 0.56) with the in situ observations near the surface layer.

  6. Atmospheric soot aerosol measurements in Moscow

    Energy Technology Data Exchange (ETDEWEB)

    Kopeikin, V.M.; Pekour, M.S. [Institute of Atmospheric Physics, Moscow (Russian Federation)

    1996-12-31

    The results of regular soot concentration measurement in Moscow`s air for the period February 1989 - December 1995 are presented. The data obtained show that the level of soot contamination increased with the rate of approximately 0.42 mkg/m{sup 3} per year. 24-hour measurements of soot concentration and atmospheric boundary layer (ABL) parameters were carried out during 3 campaigns: May-June 1990, February 1991 and October-November 1993. Direct comparisons of local soot concentration with ABL characteristics reveals certain relationships, but also shows that local contamination strongly depends on many other parameters, such as source productivity, chemical reactions, air mass pre-history and so on.

  7. Design of automatic control and measurement software for radioactive aerosol continuity monitor

    International Nuclear Information System (INIS)

    Mao Yong; Li Aiwu

    1997-01-01

    The radioactive aerosol continuity measurement is very important for the development of nuclear industry, and it is the major method to measure and find out the leakage of radioactive material. Radioactive aerosol continuity monitor is the advanced method for the radioactive aerosol continuity measurement. With the development of nuclear industry and nuclear power station, it is necessary to design and automatic continuity measurement device. Because of this reason, the authors developed the first unit of radioactive aerosol continuity monitor and adopted the ministry appraisal. The design idea and method of automatic control and measurement for radioactive aerosol continuity monitor are discussed

  8. Competing Atmospheric and Surface-Driven Impacts of Absorbing Aerosols on the East Asian Summer Monsoon

    Science.gov (United States)

    Persad, G.; Paynter, D.; Ming, Y.; Ramaswamy, V.

    2015-12-01

    Absorbing aerosols, by attenuating shortwave radiation within the atmosphere and reemitting it as longwave radiation, redistribute energy both vertically within the surface-atmosphere column and horizontally between polluted and unpolluted regions. East Asia has the largest concentrations of anthropogenic absorbing aerosols globally, and these, along with the region's scattering aerosols, have both reduced the amount of solar radiation reaching the Earth's surface regionally ("solar dimming") and increased shortwave absorption within the atmosphere, particularly during the peak months of the East Asian Summer Monsoon (EASM). We here analyze how atmospheric absorption and surface solar dimming compete in driving the response of EASM circulation to anthropogenic absorbing aerosols, which dominates, and why—issues of particular importance for predicting how the EASM will respond to projected changes in absorbing and scattering aerosol emissions in the future. We probe these questions in a state-of-the-art general circulation model (GCM) using a combination of realistic and idealized aerosol perturbations that allow us to analyze the relative influence of absorbing aerosols' atmospheric and surface-driven impacts on EASM circulation. In combination, our results make clear that, although absorption-driven dimming has a less detrimental effect on EASM circulation than purely scattering-driven dimming, aerosol absorption is still a net impairment to EASM strength when both its atmospheric and surface effects are considered. Because atmospheric heating is not efficiently conveyed to the surface, the surface dimming and associated cooling from even a pure absorber is sufficient to counteract its atmospheric heating, resulting in a net reduction in EASM strength. These findings elevate the current understanding of the impacts of aerosol absorption on the EASM, improving our ability to diagnose EASM responses to current and future regional changes in aerosol emissions.

  9. Physical and chemical characterization of urban winter-time aerosols by mobile measurements in Helsinki, Finland

    Science.gov (United States)

    Pirjola, Liisa; Niemi, Jarkko V.; Saarikoski, Sanna; Aurela, Minna; Enroth, Joonas; Carbone, Samara; Saarnio, Karri; Kuuluvainen, Heino; Kousa, Anu; Rönkkö, Topi; Hillamo, Risto

    2017-06-01

    A two-week measurement campaign by a mobile laboratory van was performed in urban environments in the Helsinki metropolitan area, Finland, in winter 2012, to obtain a comprehensive view on aerosol properties and sources. The abundances and physico-chemical properties of particles varied strongly in time and space, depending on the main sources of aerosols. Four major types of winter aerosol were recognized: 1) clean background aerosol with low particle number (Ntot) and lung deposited surface area (LDSA) concentrations due to marine air flows from the Atlantic Ocean; 2) long-range transported (LRT) pollution aerosol due to air flows from eastern Europe where the particles were characterized by the high contribution of oxygenated organic aerosol (OOA) and inorganic species, particularly sulphate, but low BC contribution, and their size distribution possessed an additional accumulation mode; 3) fresh smoke plumes from residential wood combustion in suburban small houses, these particles were characterized by high biomass burning organic aerosol (BBOA) and black carbon (BC) concentrations; and 4) fresh emissions from traffic while driving on busy streets in the city centre and on the highways during morning rush hours. This aerosol was characterized by high concentration of Ntot, LDSA, small particles in the nucleation mode, as well as high hydrocarbon-like organic aerosol (HOA) and BC concentrations. In general, secondary components (OOA, NO3, NH4, and SO4) dominated the PM1 chemical composition during the LRT episode accounting for 70-80% of the PM1 mass, whereas fresh primary emissions (BC, HOA and BBOA) dominated the local traffic and wood burning emissions. The major individual particle types observed with electron microscopy analysis (TEM/EDX) were mainly related to residential wood combustion (K/S/C-rich, soot, other C-rich particles), traffic (soot, Si/Al-rich, Fe-rich), heavy fuel oil combustion in heat plants or ships (S with V-Ni-Fe), LRT pollutants (S

  10. Acid aerosol measurement method intercomparisons: An outdoor smog chamber study

    International Nuclear Information System (INIS)

    Ellestad, T.G.; Barnes, H.M.; Kamens, R.M.; McDow, S.R.; Sickles, J.E. II; Hodson, L.L.; Waldman, J.M.; Randtke, S.J.; Lane, D.D.; Springston, S.R.; Koutrakis, P.; Thurston, G.D.

    1991-01-01

    A workshop on the measurement of acid aerosols indicated that the sampling methods in use had not been intercompared. Following two laboratory pilot studies, EPA sponsored tests in an outdoor smog chamber with a variety of test aerosols, including sulfuric acid only, photochemical smog with added sulfuric acid, photo-chemical smog with added sulfuric acid and dust, and dust followed by photochemical smog with added sulfuric acid. Two experiments of each type were conducted. Six groups, several of which were active in ambient acid aerosol measurements, participated by operating duplicate samplers for each experiment. Five groups employed a similar method, in which ammonia is removed from the sample stream by diffusion, particles are removed by Teflon filter, and hydrogen ion on the Teflon filter is determined by pH electrode. However, differences existed in the method's implementation among groups in physical design, flow rate, procedures, and analysis. The sixth group's method did not use a diffusion denuder for ammonia and had several other important differences. Besides hydrogen ion, seven other species were reported by most of the groups, including particle phase sulfate, ammonium, and nitrate, and gas phase sulfur dioxide, ammonia, nitric acid, and nitrous acid. Results of the inter-comparison will be presented

  11. Aerosol classification using airborne High Spectral Resolution Lidar measurements – methodology and examples

    Directory of Open Access Journals (Sweden)

    S. P. Burton

    2012-01-01

    Full Text Available The NASA Langley Research Center (LaRC airborne High Spectral Resolution Lidar (HSRL on the NASA B200 aircraft has acquired extensive datasets of aerosol extinction (532 nm, aerosol optical depth (AOD (532 nm, backscatter (532 and 1064 nm, and depolarization (532 and 1064 nm profiles during 18 field missions that have been conducted over North America since 2006. The lidar measurements of aerosol intensive parameters (lidar ratio, depolarization, backscatter color ratio, and spectral depolarization ratio are shown to vary with location and aerosol type. A methodology based on observations of known aerosol types is used to qualitatively classify the extensive set of HSRL aerosol measurements into eight separate types. Several examples are presented showing how the aerosol intensive parameters vary with aerosol type and how these aerosols are classified according to this new methodology. The HSRL-based classification reveals vertical variability of aerosol types during the NASA ARCTAS field experiment conducted over Alaska and northwest Canada during 2008. In two examples derived from flights conducted during ARCTAS, the HSRL classification of biomass burning smoke is shown to be consistent with aerosol types derived from coincident airborne in situ measurements of particle size and composition. The HSRL retrievals of AOD and inferences of aerosol types are used to apportion AOD to aerosol type; results of this analysis are shown for several experiments.

  12. HSRL-2 aerosol optical measurements and microphysical retrievals vs. airborne in situ measurements during DISCOVER-AQ 2013: an intercomparison study

    Science.gov (United States)

    Sawamura, Patricia; Moore, Richard H.; Burton, Sharon P.; Chemyakin, Eduard; Müller, Detlef; Kolgotin, Alexei; Ferrare, Richard A.; Hostetler, Chris A.; Ziemba, Luke D.; Beyersdorf, Andreas J.; Anderson, Bruce E.

    2017-06-01

    We present a detailed evaluation of remotely sensed aerosol microphysical properties obtained from an advanced, multi-wavelength high-spectral-resolution lidar (HSRL-2) during the 2013 NASA DISCOVER-AQ field campaign. Vertically resolved retrievals of fine-mode aerosol number, surface-area, and volume concentration as well as aerosol effective radius are compared to 108 collocated, airborne in situ measurement profiles in the wintertime San Joaquin Valley, California, and in summertime Houston, Texas. An algorithm for relating the dry in situ aerosol properties to those obtained by the HSRL at ambient relative humidity is discussed. We show that the HSRL-2 retrievals of ambient fine-mode aerosol surface-area and volume concentrations agree with the in situ measurements to within 25 and 10 %, respectively, once hygroscopic growth adjustments have been applied to the dry in situ data. Despite this excellent agreement for the microphysical properties, extinction and backscatter coefficients at ambient relative humidity derived from the in situ aerosol measurements using Mie theory are consistently smaller than those measured by the HSRL, with average differences of 31 ± 5 % and 53 ± 11 % for California and Texas, respectively. This low bias in the in situ estimates is attributed to the presence of coarse-mode aerosol that are detected by HSRL-2 but that are too large to be well sampled by the in situ instrumentation. Since the retrieval of aerosol volume is most relevant to current regulatory efforts targeting fine particle mass (PM2. 5), these findings highlight the advantages of an advanced 3β + 2α HSRL for constraining the vertical distribution of the aerosol volume or mass loading relevant for air quality.

  13. Coupled retrieval of aerosol properties and land surface reflection using the Airborne Multiangle SpectroPolarimetric Imager

    Science.gov (United States)

    Xu, Feng; van Harten, Gerard; Diner, David J.; Kalashnikova, Olga V.; Seidel, Felix C.; Bruegge, Carol J.; Dubovik, Oleg

    2017-07-01

    The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) has been flying aboard the NASA ER-2 high-altitude aircraft since October 2010. In step-and-stare operation mode, AirMSPI acquires radiance and polarization data in bands centered at 355, 380, 445, 470*, 555, 660*, 865*, and 935 nm (* denotes polarimetric bands). The imaged area covers about 10 km by 11 km and is typically observed from nine viewing angles between ±66° off nadir. For a simultaneous retrieval of aerosol properties and surface reflection using AirMSPI, an efficient and flexible retrieval algorithm has been developed. It imposes multiple types of physical constraints on spectral and spatial variations of aerosol properties as well as spectral and temporal variations of surface reflection. Retrieval uncertainty is formulated by accounting for both instrumental errors and physical constraints. A hybrid Markov-chain/adding-doubling radiative transfer (RT) model is developed to combine the computational strengths of these two methods in modeling polarized RT in vertically inhomogeneous and homogeneous media, respectively. Our retrieval approach is tested using 27 AirMSPI data sets with low to moderately high aerosol loadings, acquired during four NASA field campaigns plus one AirMSPI preengineering test flight. The retrieval results including aerosol optical depth, single-scattering albedo, aerosol size and refractive index are compared with Aerosol Robotic Network reference data. We identify the best angular combinations for 2, 3, 5, and 7 angle observations from the retrieval quality assessment of various angular combinations. We also explore the benefits of polarimetric and multiangular measurements and target revisits in constraining aerosol property and surface reflection retrieval.

  14. Measurements of organic gases during aerosol formation events in the boreal forest atmosphere during QUEST

    Directory of Open Access Journals (Sweden)

    K. Sellegri

    2005-01-01

    Full Text Available Biogenic VOCs are important in the growth and possibly also in the early stages of formation of atmospheric aerosol particles. In this work, we present 10 min-time resolution measurements of organic trace gases at Hyytiälä, Finland during March 2002. The measurements were part of the project QUEST (Quantification of Aerosol Nucleation in the European Boundary Layer and took place during a two-week period when nucleation events occurred with various intensities nearly every day. Using a ground-based Chemical Ionization Mass Spectrometer (CIMS instrument, the following trace gases were detected: acetone, TMA, DMA, mass 68amu (candidate=isoprene, monoterpenes, methyl vinyl ketone (MVK and methacrolein (MaCR and monoterpene oxidation products (MTOP. For all of them except for the amines, we present daily variations during different classes of nucleation events, and non-event days. BVOC oxidation products (MVK, MaCR and MTOP show a higher ratio to the CS on event days compared to non-event days, indicating that their abundance relative to the surface of aerosol available is higher on nucleation days. Moreover, BVOC oxidation products are found to show significant correlations with the condensational sink (CS on nucleation event days, which indicates that they are representative of less volatile organic compounds that contribute to the growth of the nucleated particles and generally secondary organic aerosol formation. Behaviors of BVOC on event and non event days are compared to the behavior of CO.

  15. Retrievals of aerosol microphysics from simulations of spaceborne multiwavelength lidar measurements

    Science.gov (United States)

    Whiteman, David N.; Pérez-Ramírez, Daniel; Veselovskii, Igor; Colarco, Peter; Buchard, Virginie

    2018-01-01

    In support of the Aerosol, Clouds, Ecosystems mission, simulations of a spaceborne multiwavelength lidar are performed based on global model simulations of the atmosphere along a satellite orbit track. The yield for aerosol microphysical inversions is quantified and comparisons are made between the aerosol microphysics inherent in the global model and those inverted from both the model's optical data and the simulated three backscatter and two extinction lidar measurements, which are based on the model's optical data. We find that yield can be significantly increased if inversions based on a reduced optical dataset of three backscatter and one extinction are acceptable. In general, retrieval performance is better for cases where the aerosol fine mode dominates although a lack of sensitivity to particles with sizes less than 0.1 μm is found. Lack of sensitivity to coarse mode cases is also found, in agreement with earlier studies. Surface area is generally the most robustly retrieved quantity. The work here points toward the need for ancillary data to aid in the constraints of the lidar inversions and also for joint inversions involving lidar and polarimeter measurements.

  16. Modeling the South American regional smoke plume: aerosol optical depth variability and surface shortwave flux perturbation

    Directory of Open Access Journals (Sweden)

    N. E. Rosário

    2013-03-01

    Full Text Available Intra-seasonal variability of smoke aerosol optical depth (AOD and downwelling solar irradiance at the surface during the 2002 biomass burning season in South America was modeled using the Coupled Chemistry-Aerosol-Tracers Transport model with the Brazilian developments on the Regional Atmospheric Modeling System (CCATT-BRAMS. Measurements of total and fine mode fraction (FMF AOD from the AErosol RObotic NETwork (AERONET and solar irradiance at the surface from the Solar Radiation Network (SolRad-NET were used to evaluate model results. In general, the major features associated with AOD evolution over the southern part of the Amazon basin and cerrado ecosystem are captured by the model. The main discrepancies were found for high aerosol loading events. In the northeastern portion of the Amazon basin the model systematically underestimated total AOD, as expected, since smoke contribution is not dominant as it is in the southern portion and emissions other than smoke were not considered in the simulation. Better agreement was obtained comparing the model results with observed FMF AOD, which pointed out the relevance of coarse mode aerosol emission in that region. Likewise, major discrepancies over cerrado during high AOD events were found to be associated with coarse mode aerosol omission in our model. The issue of high aerosol loading events in the southern part of the Amazon was related to difficulties in predicting the smoke AOD field, which was discussed in the context of emissions shortcomings. The Cuiabá cerrado site was the only one where the highest quality AERONET data were unavailable for both total and FMF AOD. Thus, lower quality data were used. Root-mean-square error (RMSE between the model and observed FMF AOD decreased from 0.34 to 0.19 when extreme AOD events (FMF AOD550 nm ≥ 1.0 and Cuiabá were excluded from the analysis. Downward surface solar irradiance comparisons also followed similar trends when extreme AOD were excluded

  17. Sea spray aerosol fluxes in the Baltic Sea region: Comparison of the WAM model with measurements

    Science.gov (United States)

    Markuszewski, Piotr; Kosecki, Szymon; Petelski, Tomasz

    2017-08-01

    Sea spray aerosol flux is an important element of sub-regional climate modeling. The majority of works related to this topic concentrate on open ocean research rather than on smaller, inland seas, e.g., the Baltic Sea. The Baltic Sea is one of the largest brackish inland seas by area, where major inflows of oceanic waters are rare. Furthermore, surface waves in the Baltic Sea have a relatively shorter lifespan in comparison with oceanic waves. Therefore, emission of sea spray aerosol may differ greatly from what is known from oceanic research and should be investigated. This article presents a comparison of sea spray aerosol measurements carried out on-board the s/y Oceania research ship with data calculated in accordance to the WAM model. The measurements were conducted in the southern region of the Baltic Sea during four scientific cruises. The gradient method was used to determinate aerosol fluxes. The fluxes were calculated for particles of diameter in range of 0.5-47 μm. The correlation between wind speed measured and simulated has a good agreement (correlation in range of 0.8). The comparison encompasses three different sea spray generation models. First, function proposed by Massel (2006) which is based only on wave parameters, such as significant wave height and peak frequency. Second, Callaghan (2013) which is based on Gong (2003) model (wind speed relation), and a thorough experimental analysis of whitecaps. Third, Petelski et al. (2014) which is based on in-situ gradient measurements with the function dependent on wind speed. The two first models which based on whitecaps analysis are insufficient. Moreover, the research shows strong relation between aerosol emission and wind speed history.

  18. Impact of surface ocean conditions and aerosol provenance on the dissolution of aerosol manganese, cobalt, nickel and lead in seawater

    OpenAIRE

    Fishwick, MP; Ussher, SJ; Sedwick, PN; Lohan, MC; Worsfold, PJ; Buck, KN; Church, TM

    2018-01-01

    © 2017. Atmospheric deposition is an important pathway by which bioactive trace metals are delivered to the surface ocean. The proportions of total aerosol trace metals that dissolve in seawater, and thus become available to biota, are not well constrained and are therefore a key uncertainty when estimating atmospheric fluxes of these elements to surface waters. The aim of this study was to elucidate the main physico-chemical controls on the dissolution of the bioactive trace metals manganese...

  19. Retrievals and uncertainty analysis of aerosol single scattering albedo from MFRSR measurements

    International Nuclear Information System (INIS)

    Yin, Bangsheng; Min, Qilong; Joseph, Everette

    2015-01-01

    Aerosol single scattering albedo (SSA) can be retrieved from the ratio of diffuse horizontal and direct normal fluxes measured from multifilter rotating shadowband radiometer (MFRSR). In this study, the measurement channels at 415 nm and 870 nm are selected for aerosol optical depth (AOD) and Angstrom coefficient retrievals, and the measurements at 415 nm are used for aerosol SSA retrievals with the constraint of retrieved Angstrom coefficient. We extensively assessed various issues impacting on the accuracy of SSA retrieval from measurements to input parameters and assumptions. For cloud-free days with mean aerosol loading of 0.13–0.60, our sensitivity study indicated that: (1) 1% calibration uncertainty can result in 0.8–3.7% changes in retrieved SSA; (2) without considering the cosine respond correction and/or forward scattering correction will result in underestimation of 1.1–3.3% and/or 0.73% in retrieved SSA; (3) an overestimation of 0.1 in asymmetry factor can result in an underestimation of 2.54–3.4% in retrieved SSA; (4) for small aerosol loading (e.g., 0.13), the uncertainty associated with the choice of Rayleigh optical depth value can result in non-negligible change in retrieved SSA (e.g., 0.015); (5) an uncertainty of 0.05 for surface albedo can result in changes of 1.49–5.4% in retrieved SSA. We applied the retrieval algorithm to the MFRSR measurements at the Atmospheric Radiation Measurements (ARM) Southern Great Plains (SGP) site. The retrieved results of AOD, Angstrom coefficient, and SSA are basically consistent with other independent measurements from co-located instruments at the site. - Highlights: • Aerosol SSA is derived from MFRSR measured diffuse to direct normal irradiance ratio. • We extensively assessed various issues impacting on the accuracy of SSA retrieval. • The issues are mainly from measurements and model input parameters and assumptions. • We applied the retrieval algorithm to the MFRSR measurements at ARM SGP

  20. Quantifying aerosol mixing state with entropy and diversity measures

    Science.gov (United States)

    Riemer, N.; West, M.

    2013-11-01

    This paper presents the first quantitative metric for aerosol population mixing state, defined as the distribution of per-particle chemical species composition. This new metric, the mixing state index χ, is an affine ratio of the average per-particle species diversity Dα and the bulk population species diversity Dγ, both of which are based on information-theoretic entropy measures. The mixing state index χ enables the first rigorous definition of the spectrum of mixing states from so-called external mixture to internal mixture, which is significant for aerosol climate impacts, including aerosol optical properties and cloud condensation nuclei activity. We illustrate the usefulness of this new mixing state framework with model results from the stochastic particle-resolved model PartMC-MOSAIC. These results demonstrate how the mixing state metrics evolve with time for several archetypal cases, each of which isolates a specific process such as coagulation, emission, or condensation. Further, we present an analysis of the mixing state evolution for a complex urban plume case, for which these processes occur simultaneously. We additionally derive theoretical properties of the mixing state index and present a family of generalized mixing state indexes that vary in the importance assigned to low-mass-fraction species.

  1. Light scattering measurements with Titan's aerosols analogues produced by dusty plasma

    Science.gov (United States)

    Hadamcik, E.; Renard, J.-B.; Szopa, C.; Cernogora, G.; Levasseur-Regourd, A. C.

    The Titan s atmosphere contains solid aerosols produced by the photochemistry of nitrogen and methane These aerosols are at the origin of the characteristic brown yellow colour of Titan During the descent of the Huygens probe the 14 th January 2005 optical measurements of the Titan s haze and Titan s surface have been done In order to explain the obtained results laboratory simulations are necessary We produce analogues of the Titan s aerosols in a RF capacitively coupled low-pressure plasma in a N 2 --CH 4 mixture representative of the Titan s atmosphere Szopa et al 2006 Szopa et al this conference The morphology of the produced solid aerosols is observed by SEM analyses They are quasi spherical and their mean size is function of the plasma conditions Moreover their colour changes from yellow to brown as a function of CH 4 ratio in the plasma In order to have information on the optical properties of the produced aerosols measurements have been performed with the PROGRA2 experiment Renard et al 2002 The PROGRA2 experiment measures the phase dependence of the linear polarization of the light scattered by dust particles for two wavelengths 543 5 nm and 632 8 nm The particles are lifted either in microgravity in the CNES ESA dedicated airplane or by an air-draught in ground-based conditions The aim of this work is to build a database for further modelling of the optical properties of Titan s in connection with the Huygens data These particles have also an astrophysical interest as organic compounds Hadamcik et

  2. Light absorption by pollution, dust, and biomass burning aerosols: a global model study and evaluation with AERONET measurements

    Directory of Open Access Journals (Sweden)

    Mian Chin

    2009-09-01

    Full Text Available Atmospheric aerosol distributions from 2000 to 2007 are simulated with the Goddard Chemistry Aerosol Radiation and Transport (GOCART model to attribute light absorption by aerosol to its composition and sources from pollution, dust, and biomass burning. The 8-year, global averaged total aerosol optical depth (τ, absorption optical depth (τa, and single scattering albedo (ω at 550 nm are estimated at 0.14, 0.0086, and 0.95, respectively, with sulfate making the largest fraction of τ (37%, followed by dust (30%, sea salt (16%, organic matter (OM (13%, and black carbon (BC (4%. BC and dust account for 43% and 53% of τa, respectively. From a model experiment with "tagged" sources, natural aerosols are estimated to be 58% of τ and 53% of τa, with pollution and biomass burning aerosols to share the rest. Comparing with data from the surface sunphotometer network AERONET, the model tends to reproduce much better the AERONET direct measured data of τ and the Ångström exponent (α than its retrieved quantities of ω and τa. Relatively small in its systematic bias of τ for pollution and dust regions, the model tends to underestimate τ for biomass burning aerosols by 30–40%. The modeled α is 0.2–0.3 too low (particle too large for pollution and dust aerosols but 0.2–0.3 too high (particle too small for the biomass burning aerosols, indicating errors in particle size distributions in the model. Still, the model estimated ω is lower in dust regions and shows a much stronger wavelength dependence for biomass burning aerosols but a weaker one for pollution aerosols than those quantities from AERONET. These comparisons necessitate model improvements on aerosol size distributions, the refractive indices of dust and black carbon aerosols, and biomass burning emissions in order to better quantify the aerosol absorption in the atmosphere.

  3. Aerosol Sources, Absorption, and Intercontinental Transport: Synergies among Models, Remote Sensing, and Atmospheric Measurements

    Science.gov (United States)

    Chin, Mian; Ginoux, Paul; Dubovik, Oleg; Holben, Brent; Kaufman, Yoram; chu, Allen; Anderson, Tad; Quinn, Patricia

    2003-01-01

    Aerosol climate forcing is one of the largest uncertainties in assessing the anthropogenic impact on the global climate system. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, our limited knowledge of aerosol mixing state and optical properties, and the consequences of intercontinental transport of aerosols and their precursors. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt, from anthropogenic, biomass burning, and natural sources. We compare the model calculated aerosol extinction and absorption with those quantities from the ground-based sun photometer measurements from AERONET at several different wavelengths and the field observations from ACE-Asia, and model calculated total aerosol optical depth and fine mode fractions with the MODIS satellite retrieval. We will also estimate the intercontinental transport of pollution and dust aerosols from their source regions to other areas in different seasons.

  4. Aerosol Optical Retrieval and Surface Reflectance from Airborne Remote Sensing Data over Land

    Directory of Open Access Journals (Sweden)

    Cristiana Bassani

    2010-06-01

    Full Text Available Quantitative analysis of atmospheric optical properties and surface reflectance can be performed by applying radiative transfer theory in the Atmosphere-Earth coupled system, for the atmospheric correction of hyperspectral remote sensing data. This paper describes a new physically-based algorithm to retrieve the aerosol optical thickness at 550nm (τ550 and the surface reflectance (ρ from airborne acquired data in the atmospheric window of the Visible and Near-Infrared (VNIR range. The algorithm is realized in two modules. Module A retrieves τ550 with a minimization algorithm, then Module B retrieves the surface reflectance ρ for each pixel of the image. The method was tested on five remote sensing images acquired by an airborne sensor under different geometric conditions to evaluate the reliability of the method. The results, τ550 and ρ, retrieved from each image were validated with field data contemporaneously acquired by a sun-sky radiometer and a spectroradiometer, respectively. Good correlation index, r, and low root mean square deviations, RMSD, were obtained for the τ550 retrieved by Module A (r2 = 0.75, RMSD = 0.08 and the ρ retrieved by Module B (r2 ≤ 0.9, RMSD ≤ 0.003. Overall, the results are encouraging, indicating that the method is reliable for optical atmospheric studies and the atmospheric correction of airborne hyperspectral images. The method does not require additional at-ground measurements about at-ground reflectance of the reference pixel and aerosol optical thickness.

  5. Trend of surface solar radiation over Asia simulated by aerosol transport-climate model

    Science.gov (United States)

    Takemura, T.; Ohmura, A.

    2009-12-01

    Long-term records of surface radiation measurements indicate a decrease in the solar radiation between the 1950s and 1980s (“global dimming”), then its recovery afterward (“global brightening”) at many locations all over the globe [Wild, 2009]. On the other hand, the global brightening is delayed over the Asian region [Ohmura, 2009]. It is suggested that these trends of the global dimming and brightening are strongly related with a change in aerosol loading in the atmosphere which affect the climate change through the direct, semi-direct, and indirect effects. In this study, causes of the trend of the surface solar radiation over Asia during last several decades are analyzed with an aerosol transport-climate model, SPRINTARS. SPRINTARS is coupled with MIROC which is a general circulation model (GCM) developed by Center for Climate System Research (CCSR)/University of Tokyo, National Institute for Environmental Studies (NIES), and Frontier Research Center for Global Change (FRCGC) [Takemura et al., 2000, 2002, 2005, 2009]. The horizontal and vertical resolutions are T106 (approximately 1.1° by 1.1°) and 56 layers, respectively. SPRINTARS includes the transport, radiation, cloud, and precipitation processes of all main tropospheric aerosols (black and organic carbons, sulfate, soil dust, and sea salt). The model treats not only the aerosol mass mixing ratios but also the cloud droplet and ice crystal number concentrations as prognostic variables, and the nucleation processes of cloud droplets and ice crystals depend on the number concentrations of each aerosol species. Changes in the cloud droplet and ice crystal number concentrations affect the cloud radiation and precipitation processes in the model. Historical emissions, that is consumption of fossil fuel and biofuel, biomass burning, aircraft emissions, and volcanic eruptions are prescribed from database provided by the Aerosol Model Intercomparison Project (AeroCom) and the latest IPCC inventories

  6. Optical particle counter measurement of marine aerosol hygroscopic growth

    Directory of Open Access Journals (Sweden)

    J. R. Snider

    2008-04-01

    Full Text Available A technique is developed for the determination of the hygroscopic growth factor of dry particles with diameter between 0.3 and 0.6 μm and is applied to measurements made during the second Dynamics and Chemistry of Marine Stratocumulus experiment (DYCOMS-II. Two optical particle counters are utilized, one measures the aerosol size spectrum at ambient relative humidity and the other simultaneously dries the aerosol prior to light scattering detection. Growth factors are based on measurements made in the region of the Mie scattering curve where scattered light intensity increases monotonically with dry and wet particle diameter, i.e. D<0.9 μm. Factors influencing the accuracy of the measurement are evaluated, including particle drying, refractive index and shape. Growth factors at 90±3% ambient relative humidity in marine airmasses 400 km west of San Diego, California range between 1.5 and 1.8. This suggests that a significant fraction of the particle mass, between 40 and 70%, is either non-hygroscopic or weakly hygroscopic.

  7. Surface aerosol and rehabilitation properties of ground-level atmosphere in the mountains of the North Caucasus

    Science.gov (United States)

    Reps, Valentina; Efimenko, Natalia; Povolotskaya, Nina; Abramtsova, Anna; Ischenko, Dmitriy; Senik, Irina; Slepikh, Victor

    2017-04-01

    The rehabilitative properties (RP) of ground-level atmosphere (GA) of Russian resorts are considered as natural healing resources and received state legal protection [1]. Due to global urbanization the chemical composition and particle size distribution of the surface aerosol are changing rapidly. However, the influence of surface aerosol on the RP of GA has been insufficiently studied. At the resort region of the North Caucasus complex monitoring (aerosol, trace gases NOx, CO, O3, CH4; periodically - heavy metals) is performed at two high levels (860 masl - a park zone of a large mountain resort, 2070 masl - alpine grassland, the net station). The results of the measurements are used in programs of bioclimatic, landscape and medical monitoring to specify the influence of aerosol on rehabilitation properties of the environment and human adaptative reserves. The aerosol particles of size range 500-1000 nm are used as a marker of the pathogenic effect of aerosol [2]. In the conditions of regional urbanization and complicated mountain atmospheric circulation the influence of aerosol on RP of GA and the variability of heart rhythm with the volunteers at different heights were investigated. At the height of 860 masl (urbanized resort) there have been noticed aerosol variations in the range of 0,04-0,35 particles/cm3 (slightly aerosol polluted), in mountain conditions - background pollution aerosol level. The difference of bioclimatic conditions at the specified high-rise levels has been referred to the category of contrasts. The natural aero ionization ∑(N+)+(N-) varied from 960 ion/cm3 to 1460 ion/cm3 in the resort park (860 m); from 1295 ion/cm3 to 4850 ion/cm3 on the Alpine meadow (2070 m); from 1128 ion/cm3 to 3420 ion/cm3 - on the tested site near the edge of the pinewood (1720 m). In the group of volunteers the trip from low-hill terrain zone (860 m) to the lower zone of highlands (2070 m) caused the activation of neuro and humoral regulation, vegetative and

  8. Unipolar charging of nanoparticles by the Surface-discharge Microplasma Aerosol Charger (SMAC)

    Science.gov (United States)

    Kwon, Soon-Bark; Sakurai, Hiromu; Seto, Takafumi

    2007-08-01

    In this paper, we report the development of a novel unipolar charger for nanoparticles, a system that achieves low particle loss and high charging efficiency without the use of sheath air. The efficient unipolar charging of the system is realized mainly by the surface-discharge microplasma unit, a device previously applied with good success to the neutralization or charging of submicron particles [Kwon et al., 2005, Aerosol Sci. Technol., 39, 987-1001; 2006, J. Aerosol Sci., 37, 483-499]. The unipolar charger generates unipolar ions using the surface discharge of a single electrode with a DC pulse supply. This marks an advance from our previous method of generating bipolar ions with the use of dual electrodes in earlier studies. We evaluated the efficiency of the penetration (or loss) and charging of nanoparticles in the size range of 3-15 nm, then compared the charging efficiencies measured with those predicted by diffusion charging theory. More than 90% of inlet nanoparticles penetrated the charger (less than 10% of the particle were lost) without the use of sheath air. Other chargers have only realized this high penetration efficiency by relying on sheath air flow. Moreover, the measured charging efficiencies agreed well with those predicted by diffusion charging theory and were somewhat higher and more size-dependent than the charging efficiencies of other nanoparticle chargers.

  9. Unipolar charging of nanoparticles by the Surface-discharge Microplasma Aerosol Charger (SMAC)

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Soon-Bark [Korea Railroad Research Institute, Environment and Fire Control Research Team (Korea, Republic of); Sakurai, Hiromu [National Institute of Advanced Industrial Science and Technology, National Metrology Institute of Japan (Japan); Seto, Takafumi [National Institute of Advanced Industrial Science and Technology, Advanced Manufacturing Research Institute (Japan)], E-mail: t.seto@aist.go.jp

    2007-08-15

    In this paper, we report the development of a novel unipolar charger for nanoparticles, a system that achieves low particle loss and high charging efficiency without the use of sheath air. The efficient unipolar charging of the system is realized mainly by the surface-discharge microplasma unit, a device previously applied with good success to the neutralization or charging of submicron particles [Kwon et al., 2005, Aerosol Sci. Technol., 39, 987-1001; 2006, J. Aerosol Sci., 37, 483-499]. The unipolar charger generates unipolar ions using the surface discharge of a single electrode with a DC pulse supply. This marks an advance from our previous method of generating bipolar ions with the use of dual electrodes in earlier studies. We evaluated the efficiency of the penetration (or loss) and charging of nanoparticles in the size range of 3-15 nm, then compared the charging efficiencies measured with those predicted by diffusion charging theory. More than 90% of inlet nanoparticles penetrated the charger (less than 10% of the particle were lost) without the use of sheath air. Other chargers have only realized this high penetration efficiency by relying on sheath air flow. Moreover, the measured charging efficiencies agreed well with those predicted by diffusion charging theory and were somewhat higher and more size-dependent than the charging efficiencies of other nanoparticle chargers.

  10. Unipolar charging of nanoparticles by the Surface-discharge Microplasma Aerosol Charger (SMAC)

    International Nuclear Information System (INIS)

    Kwon, Soon-Bark; Sakurai, Hiromu; Seto, Takafumi

    2007-01-01

    In this paper, we report the development of a novel unipolar charger for nanoparticles, a system that achieves low particle loss and high charging efficiency without the use of sheath air. The efficient unipolar charging of the system is realized mainly by the surface-discharge microplasma unit, a device previously applied with good success to the neutralization or charging of submicron particles [Kwon et al., 2005, Aerosol Sci. Technol., 39, 987-1001; 2006, J. Aerosol Sci., 37, 483-499]. The unipolar charger generates unipolar ions using the surface discharge of a single electrode with a DC pulse supply. This marks an advance from our previous method of generating bipolar ions with the use of dual electrodes in earlier studies. We evaluated the efficiency of the penetration (or loss) and charging of nanoparticles in the size range of 3-15 nm, then compared the charging efficiencies measured with those predicted by diffusion charging theory. More than 90% of inlet nanoparticles penetrated the charger (less than 10% of the particle were lost) without the use of sheath air. Other chargers have only realized this high penetration efficiency by relying on sheath air flow. Moreover, the measured charging efficiencies agreed well with those predicted by diffusion charging theory and were somewhat higher and more size-dependent than the charging efficiencies of other nanoparticle chargers

  11. Airborne lidar aerosol measurements during the ASSESS II mission.

    Science.gov (United States)

    Werner, C; Bachstein, F; Dietz, S; Herrmann, H; Köpp, F; Löffler, H

    1978-07-01

    During May 1977 the Airborne Science Spacelab Experiments System Simulation (ASSESS II) took place, using the NASA CV 990 aircraft. A ND:glass lidar system, measuring the aerosol mass concentration over large areas, was proxy operated by trained ''Payload Specialists.'' The main part of this paper is concerned with the lidar experiment and its results. The participants in the mission viewed it as a tool for judging their spacelab science management and as the final stage of a guide for future planning of experiments. A general result that has emerged is that, for a real spacelab mission, the handling of remote sensing experiments should be fully automatic.

  12. Informing Aerosol Transport Models With Satellite Multi-Angle Aerosol Measurements

    Science.gov (United States)

    Limbacher, J.; Patadia, F.; Petrenko, M.; Martin, M. Val; Chin, M.; Gaitley, B.; Garay, M.; Kalashnikova, O.; Nelson, D.; Scollo, S.

    2011-01-01

    As the aerosol products from the NASA Earth Observing System's Multi-angle Imaging SpectroRadiometer (MISR) mature, we are placing greater focus on ways of using the aerosol amount and type data products, and aerosol plume heights, to constrain aerosol transport models. We have demonstrated the ability to map aerosol air-mass-types regionally, and have identified product upgrades required to apply them globally, including the need for a quality flag indicating the aerosol type information content, that varies depending upon retrieval conditions. We have shown that MISR aerosol type can distinguish smoke from dust, volcanic ash from sulfate and water particles, and can identify qualitative differences in mixtures of smoke, dust, and pollution aerosol components in urban settings. We demonstrated the use of stereo imaging to map smoke, dust, and volcanic effluent plume injection height, and the combination of MISR and MODIS aerosol optical depth maps to constrain wildfire smoke source strength. This talk will briefly highlight where we stand on these application, with emphasis on the steps we are taking toward applying the capabilities toward constraining aerosol transport models, planet-wide.

  13. The surface aerosol optical properties in the urban area of Nanjing, west Yangtze River Delta, China

    Science.gov (United States)

    Zhuang, Bingliang; Wang, Tijian; Liu, Jane; Li, Shu; Xie, Min; Han, Yong; Chen, Pulong; Hu, Qiduo; Yang, Xiu-qun; Fu, Congbin; Zhu, Jialei

    2017-01-01

    Observational studies of aerosol optical properties are useful for reducing uncertainties in estimations of aerosol radiative forcing and forecasting visibility. In this study, the observed near-surface aerosol optical properties in urban Nanjing are analysed from March 2014 to February 2016. Results show that near-surface urban aerosols in Nanjing are mainly from local emissions and the surrounding regions. They have lower loadings but are more scattering than aerosols in most cities in China. The annual mean aerosol extinction coefficient (EC), single-scattering albedo (SSA) and asymmetry parameter (ASP) at 550 nm are 381.96 Mm-1, 0.9 and 0.57, respectively. The aerosol absorption coefficient (AAC) is about 1 order of magnitude smaller than its scattering coefficient (SC). However, the absorbing aerosol has a larger Ångström exponent (AAE) value, 1.58 at 470/660 nm, about 0.2 larger than the scattering aerosols (SAE). All the aerosol optical properties follow a near-unimodal pattern, and their values are mostly concentrated around their averages, accounting for more than 60 % of the total samplings. Additionally, they have substantial seasonality and diurnal variations. High levels of SC and AAC all appear in winter due to higher aerosol and trace gas emissions. AAE (ASP) is the smallest (largest) in summer, possibly because of high relative humidity (RH) which also causes considerably larger SC and smaller SAE, although intensive gas-to-particle transformation could produce a large number of finer scattering aerosols in this season. Seasonality of EC is different from the columnar aerosol optical depth. Larger AACs appear during the rush hours of the day while SC and back-scattering coefficient (Bsp) only peak in the early morning. Aerosols are fresher in the daytime than at night-time, leading to their larger Ångström exponent and smaller ASP. Different temporal variations between AAC and SC cause the aerosols to be more absorbing (smaller SSA) in autumn

  14. Measurement-based climatology of aerosol direct radiative effect, its sensitivities, and uncertainties from a background southeast US site

    Science.gov (United States)

    Sherman, James P.; McComiskey, Allison

    2018-03-01

    Aerosol optical properties measured at Appalachian State University's co-located NASA AERONET and NOAA ESRL aerosol network monitoring sites over a nearly four-year period (June 2012-Feb 2016) are used, along with satellite-based surface reflectance measurements, to study the seasonal variability of diurnally averaged clear sky aerosol direct radiative effect (DRE) and radiative efficiency (RE) at the top-of-atmosphere (TOA) and at the surface. Aerosol chemistry and loading at the Appalachian State site are likely representative of the background southeast US (SE US), home to high summertime aerosol loading and one of only a few regions not to have warmed during the 20th century. This study is the first multi-year ground truth DRE study in the SE US, using aerosol network data products that are often used to validate satellite-based aerosol retrievals. The study is also the first in the SE US to quantify DRE uncertainties and sensitivities to aerosol optical properties and surface reflectance, including their seasonal dependence.Median DRE for the study period is -2.9 W m-2 at the TOA and -6.1 W m-2 at the surface. Monthly median and monthly mean DRE at the TOA (surface) are -1 to -2 W m-2 (-2 to -3 W m-2) during winter months and -5 to -6 W m-2 (-10 W m-2) during summer months. The DRE cycles follow the annual cycle of aerosol optical depth (AOD), which is 9 to 10 times larger in summer than in winter. Aerosol RE is anti-correlated with DRE, with winter values 1.5 to 2 times more negative than summer values. Due to the large seasonal dependence of aerosol DRE and RE, we quantify the sensitivity of DRE to aerosol optical properties and surface reflectance, using a calendar day representative of each season (21 December for winter; 21 March for spring, 21 June for summer, and 21 September for fall). We use these sensitivities along with measurement uncertainties of aerosol optical properties and surface reflectance to calculate DRE uncertainties. We also estimate

  15. Advanced characterisation of aerosol size properties from measurements of spectral optical depth using the GRASP algorithm

    Science.gov (United States)

    Torres, Benjamin; Dubovik, Oleg; Fuertes, David; Schuster, Gregory; Cachorro, Victoria Eugenia; Lapyonok, Tatsiana; Goloub, Philippe; Blarel, Luc; Barreto, Africa; Mallet, Marc; Toledano, Carlos; Tanré, Didier

    2017-10-01

    This study evaluates the potential of using aerosol optical depth (τa) measurements to characterise the microphysical and optical properties of atmospheric aerosols. With this aim, we used the recently developed GRASP (Generalized Retrieval of Aerosol and Surface Properties) code for numerical testing of six different aerosol models with different aerosol loads. The direct numerical simulations (self-consistency tests) indicate that the GRASP-AOD retrieval provides modal aerosol optical depths (fine and coarse) to within 0.01 of the input values. The retrieval of the fine-mode radius, width and volume concentration are stable and precise if the real part of the refractive index is known. The coarse-mode properties are less accurate, but they are significantly improved when additional a priori information is available. The tests with random simulated errors show that the uncertainty in the bimodal log-normal size distribution parameters increases as the aerosol load decreases. Similarly, the reduction in the spectral range diminishes the stability of the retrieved parameters. In addition to these numerical studies, we used optical depth observations at eight AERONET locations to validate our results with the standard AERONET inversion products. We found that bimodal log-normal size distributions serve as useful input assumptions, especially when the measurements have inadequate spectral coverage and/or limited accuracy, such as moon photometry. Comparisons of the mode median radii between GRASP-AOD and AERONET indicate average differences of 0.013 µm for the fine mode and typical values of 0.2-0.3 µm for the coarse mode. The dominant mode (i.e. fine or coarse) indicates a 10 % difference in mode radii between the GRASP-AOD and AERONET inversions, and the average of the difference in volume concentration is around 17 % for both modes. The retrieved values of the fine-mode τa(500) using GRASP-AOD are generally between those values obtained by the standard AERONET

  16. Aircraft Measurement of Isoprene-derived Organic Aerosol during the Southeast Nexus (SENEX) Campaign Using an Aerosol Mass Spectrometer

    Science.gov (United States)

    Xu, L.; Middlebrook, A. M.; Liao, J.; Welti, A.; Guo, H.; Lin, J. J.; Bougiatioti, A.; Weber, R. J.; Nenes, A.; Holloway, J. S.; Gilman, J.; Lerner, B. M.; Graus, M.; Warneke, C.; Trainer, M.; De Gouw, J. A.; Ng, N. L.

    2014-12-01

    Isoprene is an important precursor for secondary organic aerosol (SOA) formation due to its large global emissions and high reactivity. Recent studies have found that isoprene SOA formation via the uptake of isoprene epoxydiol (IEPOX) under low NOx conditions appears to be largely affected by anthropogenic emissions and are not well understood. Here we investigate the effects of anthropogenic emissions on isoprene SOA formation through airborne measurements above the southeastern US, which is an ideal location for this study since this area is characterized by high emissions of both anthropogenic and isoprene sources. An Aerodyne Aerosol Mass Spectrometer (AMS) was deployed aboard the NOAA WP-3D aircraft during the Southeast Nexus (SENEX) field campaign to characterize the non-refractory chemical composition of submicron aerosol. Positive Matrix Factorization (PMF) analysis was performed on the organic aerosol (OA) mass spectra to identify patterns of organic components and various OA factors were resolved. Low-volatility Oxygenated Organic Aerosol (LV-OOA) constituted a major fraction of OA. Isoprene-derived OA was also identified in certain flights and correlated well with sulfate. This result is consistent with our recent finding from ground-based measurements in Centreville during the Southern Oxidant and Aerosol Study (SOAS) field campaign that isoprene-derived OA is directly modulated by the abundance of sulfate. The vertical distribution of isoprene-derived OA will be discussed along with the timescale of the effect of sulfate on isoprene OA formation.

  17. Nine years of UV aerosol optical depth measurements at Thessaloniki, Greece

    Directory of Open Access Journals (Sweden)

    S. Kazadzis

    2007-01-01

    Full Text Available Spectral measurements of the aerosol optical depth (AOD and the Ångström coefficient were conducted at Thessaloniki, Greece (40.5° N, 22.9° E between January 1997 and December 2005 with a Brewer MKIII double-monochromator spectroradiometer. The dataset was compared with collocated measurements of a second spectroradiometer (Brewer MKII and a CIMEL sun-photometer, showing correlations of 0.93 and 0.98, respectively. A seasonal variation of the AOD was observed at Thessaloniki, with AOD values at 340 nm of 0.52 and 0.28 for August and December respectively. Back trajectories of air masses for up to 4 days were used to assess the influence of long-range transport from various regions to the aerosol load over Thessaloniki. It is shown that part of the observed seasonality can be attributed to air masses with high AOD originating from North-Eastern and Eastern directions during summertime. The analysis of the long-term record (9 years of AOD showed a downward tendency. A similar decreasing tendency was found in the record of the PM$_{10}$ aerosol measurements, which are conducted near the surface at 4 air-quality monitoring stations in the area of the city of Thessaloniki.

  18. Diffusivity measurements of volatile organics in levitated viscous aerosol particles

    Directory of Open Access Journals (Sweden)

    S. Bastelberger

    2017-07-01

    Full Text Available Field measurements indicating that atmospheric secondary organic aerosol (SOA particles can be present in a highly viscous, glassy state have spurred numerous studies addressing low diffusivities of water in glassy aerosols. The focus of these studies is on kinetic limitations of hygroscopic growth and the plasticizing effect of water. In contrast, much less is known about diffusion limitations of organic molecules and oxidants in viscous matrices. These may affect atmospheric chemistry and gas–particle partitioning of complex mixtures with constituents of different volatility. In this study, we quantify the diffusivity of a volatile organic in a viscous matrix. Evaporation of single particles generated from an aqueous solution of sucrose and small amounts of volatile tetraethylene glycol (PEG-4 is investigated in an electrodynamic balance at controlled relative humidity (RH and temperature. The evaporative loss of PEG-4 as determined by Mie resonance spectroscopy is used in conjunction with a radially resolved diffusion model to retrieve translational diffusion coefficients of PEG-4. Comparison of the experimentally derived diffusivities with viscosity estimates for the ternary system reveals a breakdown of the Stokes–Einstein relationship, which has often been invoked to infer diffusivity from viscosity. The evaporation of PEG-4 shows pronounced RH and temperature dependencies and is severely depressed for RH ≲ 30 %, corresponding to diffusivities < 10−14 cm2 s−1 at temperatures < 15 °C. The temperature dependence is strong, suggesting a diffusion activation energy of about 300 kJ mol−1. We conclude that atmospheric volatile organic compounds can be subject to severe diffusion limitations in viscous organic aerosol particles. This may enable an important long-range transport mechanism for organic material, including pollutant molecules such as polycyclic aromatic hydrocarbons (PAHs.

  19. Measurement of the deposition of aerosol particles to skin, hair and clothing

    CERN Document Server

    Bell, K F

    1998-01-01

    efficient. range 1.3 -15x10 sup - sup 3 ms sup - sup 1 were recorded, values which are approximately an order of magnitude higher than the equivalent values onto the floor of the test room. These values suggest that the exposure route of radioactive aerosol particles deposited on the skin may be more significant than hitherto had been assumed. The possible mechanisms leading to this relatively high deposition were investigated experimentally and the results suggested that a combination of factors such as the body's electrostatic field, surface temperature and surface roughness were contributors. A wind tunnel was used to carry out experiments to compare the deposition velocities of a 1.4 mu m mean diameter aerosol onto human body phantoms in a simulated outdoor environment with the values from the test chamber experiments. The measured aerosol deposition velocities were found to vary with wind velocity; values in the range 6.8 - 11x10 sup - sup 3 ms sup - sup 1 were recorded. The clearance of deposited aeroso...

  20. Aerosol absorption measurement with a sinusoidal phase modulating fiber optic photo thermal interferometer

    Science.gov (United States)

    Li, Shuwang; Shao, Shiyong; Mei, Haiping; Rao, Ruizhong

    2016-10-01

    Aerosol light absorption plays an important role in the earth's atmosphere direct and semi-direct radiate forcing, simultaneously, it also has a huge influence on the visibility impairment and laser engineering application. Although various methods have been developed for measuring aerosol light absorption, huge challenge still remains in precision, accuracy and temporal resolution. The main reason is that, as a part of aerosol light extinction, aerosol light absorption always generates synchronously with aerosol light scattering, and unfortunately aerosol light scattering is much stronger in most cases. Here, a novel photo-thermal interferometry is proposed only for aerosol absorption measurement without disturbance from aerosol scattering. The photo-thermal interferometry consists of a sinusoidal phase-modulating single mode fiber-optic interferometer. The thermal dissipation, caused by aerosol energy from photo-thermal conversion when irritated by pump laser through interferometer, is detected. This approach is completely insensitive to aerosol scattering, and the single mode fiber-optic interferometer is compact, low-cost and insensitive to the polarization shading. The theory of this technique is illustrated, followed by the basic structure of the sinusoidal phase-modulating fiber-optic interferometer and demodulation algorithms. Qualitative and quantitative analysis results show that the new photo-thermal interference is a potential approach for aerosol absorption detection and environmental pollution detection.

  1. Generation and characterization of biological aerosols for laser measurements

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Yung-Sung; Barr, E.B.

    1995-12-01

    Concerns for proliferation of biological weapons including bacteria, fungi, and viruses have prompted research and development on methods for the rapid detection of biological aerosols in the field. Real-time instruments that can distinguish biological aerosols from background dust would be especially useful. Sandia National Laboratories (SNL) is developing a laser-based, real-time instrument for rapid detection of biological aerosols, and ITRI is working with SNL scientists and engineers to evaluate this technology for a wide range of biological aerosols. This paper describes methods being used to generate the characterize the biological aerosols for these tests. In summary, a biosafe system has been developed for generating and characterizing biological aerosols and using those aerosols to test the SNL laser-based real-time instrument. Such tests are essential in studying methods for rapid detection of airborne biological materials.

  2. Seven years of aerosol scattering hygroscopic growth measurements from SGP: Factors influencing water uptake: Aerosol Scattering Hygroscopic Growth

    Energy Technology Data Exchange (ETDEWEB)

    Jefferson, A. [Cooperative Institute of Research in the Environmental Sciences, University of Colorado Boulder, Boulder Colorado USA; Earth Systems Research Laboratory, National Oceanic and Atmospheric Administration, Boulder Colorado USA; Hageman, D. [Cooperative Institute of Research in the Environmental Sciences, University of Colorado Boulder, Boulder Colorado USA; Earth Systems Research Laboratory, National Oceanic and Atmospheric Administration, Boulder Colorado USA; Morrow, H. [Earth Systems Research Laboratory, National Oceanic and Atmospheric Administration, Boulder Colorado USA; Science and Technology Corporation, Boulder Colorado USA; Mei, F. [Pacific Northwest National Laboratory, Richland Washington USA; Watson, T. [Brookhaven National Laboratory, Upton New York USA

    2017-09-11

    Long-term measurements of changes in the aerosol scattering coefficient hygroscopic growth at the U.S. Department of Energy Southern Great Plains site provide information on the seasonal as well as size and chemical dependence of aerosol hygroscopic growth. Annual average sub 10 um fRH values (the ratio of aerosol scattering at 85%/40% RH) were 1.75 and 1.87 for the gamma and kappa fit algorithms, respectively. The study found higher growth rates in the winter and spring seasons that correlated with high aerosol nitrate mass fraction. FRH, exhibited strong, but differing correlations with the scattering Ångström exponent and backscatter fraction, two optical size-dependent parameters. The aerosol organic fraction had a strong influence, with fRH decreasing with increases in the organic mass fraction and absorption Ångström exponent and increasing with the aerosol single scatter albedo. Uncertainty analysis if the fit algorithms revealed high uncertainty at low scattering coefficients and slight increases in uncertainty at high RH and fit parameters values.

  3. Effect of Surface Coating with Magnesium Stearate via Mechanical Dry Powder Coating Approach on the Aerosol Performance of Micronized Drug Powders from Dry Powder Inhalers

    OpenAIRE

    Zhou, Qi (Tony); Qu, Li; Gengenbach, Thomas; Larson, Ian; Stewart, Peter J.; Morton, David A. V.

    2012-01-01

    The objective of this study was to investigate the effect of particle surface coating with magnesium stearate on the aerosolization of dry powder inhaler formulations. Micronized salbutamol sulphate as a model drug was dry coated with magnesium stearate using a mechanofusion technique. The coating quality was characterized by X-ray photoelectron spectroscopy. Powder bulk and flow properties were assessed by bulk densities and shear cell measurements. The aerosol performance was studied by las...

  4. Jet and ultrasonic nebuliser output: use of a new method for direct measurement of aerosol output.

    OpenAIRE

    Dennis, J H; Stenton, S C; Beach, J R; Avery, A J; Walters, E H; Hendrick, D J

    1990-01-01

    Output from jet nebulisers is calibrated traditionally by weighing them before and after nebulisation, but the assumption that the weight difference is a close measure of aerosol generation could be invalidated by the concomitant process of evaporation. A method has been developed for measuring aerosol output directly by using a solute (fluoride) tracer and aerosol impaction, and this has been compared with the traditional weight loss method for two Wright, six Turbo, and four Micro-Cirrus je...

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

    Science.gov (United States)

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

    2018-03-01

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

  6. Jet and ultrasonic nebuliser output: use of a new method for direct measurement of aerosol output.

    Science.gov (United States)

    Dennis, J H; Stenton, S C; Beach, J R; Avery, A J; Walters, E H; Hendrick, D J

    1990-10-01

    Output from jet nebulisers is calibrated traditionally by weighing them before and after nebulisation, but the assumption that the weight difference is a close measure of aerosol generation could be invalidated by the concomitant process of evaporation. A method has been developed for measuring aerosol output directly by using a solute (fluoride) tracer and aerosol impaction, and this has been compared with the traditional weight loss method for two Wright, six Turbo, and four Micro-Cirrus jet nebulisers and two Microinhaler ultrasonic nebulisers. The weight loss method overestimated true aerosol output for all jet nebulisers. The mean aerosol content, expressed as a percentage of the total weight loss, varied from as little as 15% for the Wright jet nebulisers to 54% (range 45-61%) for the Turbo and Micro-Cirrus jet nebulisers under the operating conditions used. In contrast, there was no discrepancy between weight loss and aerosol output for the ultrasonic nebulisers. These findings, along with evidence of both concentrating and cooling effects from jet nebulisation, confirm that total output from jet nebulisers contains two distinct fractions, vapour and aerosol. The vapour fraction, but not the aerosol fraction, was greatly influenced by reservoir temperature within the nebuliser; so the ratio of aerosol output to total weight loss varied considerably with temperature. It is concluded that weight loss is an inappropriate method of calibrating jet nebuliser aerosol output, and that this should be measured directly.

  7. Modeling Dry Deposition of Aerosol Particles on Rough Surfaces

    Czech Academy of Sciences Publication Activity Database

    Hussein, T.; Smolík, Jiří; Kerminen, V.-M.; Kulmala, M.

    2012-01-01

    Roč. 46, č. 1 (2012), s. 44-59 ISSN 0278-6826 Institutional research plan: CEZ:AV0Z40720504 Keywords : aerosol particles * dry deposition * transport Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.780, year: 2012

  8. Intercomparison and closure calculations using measurements of aerosol species and optical properties during the Yosemite Aerosol Characterization Study

    Science.gov (United States)

    Malm, William C.; Day, Derek E.; Carrico, Christian; Kreidenweis, Sonia M.; Collett, Jeffrey L.; McMeeking, Gavin; Lee, Taehyoung; Carrillo, Jacqueline; Schichtel, Bret

    2005-07-01

    Physical and optical properties of inorganic aerosols have been extensively studied, but less is known about carbonaceous aerosols, especially as they relate to the non-urban settings such as our nation's national parks and wilderness areas. Therefore an aerosol characterization study was conceived and implemented at one national park that is highly impacted by carbonaceous aerosols, Yosemite. The primary objective of the study was to characterize the physical, chemical, and optical properties of a carbon-dominated aerosol, including the ratio of total organic matter weight to organic carbon, organic mass scattering efficiencies, and the hygroscopic characteristics of a carbon-laden ambient aerosol, while a secondary objective was to evaluate a variety of semi-continuous monitoring systems. Inorganic ions were characterized using 24-hour samples that were collected using the URG and Interagency Monitoring of Protected Visual Environments (IMPROVE) monitoring systems, the micro-orifice uniform deposit impactor (MOUDI) cascade impactor, as well as the semi-continuous particle-into-liquid sampler (PILS) technology. Likewise, carbonaceous material was collected over 24-hour periods using IMPROVE technology along with the thermal optical reflectance (TOR) analysis, while semi-continuous total carbon concentrations were measured using the Rupprecht and Patashnick (R&P) instrument. Dry aerosol number size distributions were measured using a differential mobility analyzer (DMA) and optical particle counter, scattering coefficients at near-ambient conditions were measured with nephelometers fitted with PM10 and PM2.5 inlets, and "dry" PM2.5 scattering was measured after passing ambient air through Perma Pure Nafion® dryers. In general, the 24-hour "bulk" measurements of various aerosol species compared more favorably with each other than with the semi-continuous data. Semi-continuous sulfate measurements correlated well with the 24-hour measurements, but were biased low by

  9. Dry deposition of submicron atmospheric aerosol over water surfaces in motion

    International Nuclear Information System (INIS)

    Calec, Nevenick

    2013-01-01

    conditions (central wind speed: 1, 2, 4, 5, 7.5 and 9.5 m/s), current (co-current and counter-current, water flow velocity: 0, 6 and 12 cm/s), ambient (temperature and relative humidity of the air and water temperature), the liquid surface deformations (measured significant wave height) and size distribution of aerosols released. The modeling part was to adapt the model to resistance. Slinn and Slinn (1980). This model is based on the assumption of conservation of vertical flow in the boundary layer. This one is divided into two layers: a very thin deposition layer near the surface which is water-saturated and a transfer layer located above. The transfer layer provides the particle deposition layer by turbulent diffusion and sedimentation. In the deposition layer the particles are deposited under the effect of several mechanisms such as Brownian diffusion, sedimentation, impaction and phoretic mechanisms. The main adjustments made by this work have been to take specific account of the different classes of particle size distribution, the spectrum variation as a function of hygroscopicity, and mechanisms of aggregation. It is integrated mechanisms of diffusiophoresis and thermophoresis, respectively produced by the evaporation of water and the temperature gradient at the air-water interface. To account for hygroscopic uranine aerosols, the deposition rates are analyzed in terms of humidity and rescaled by the friction velocity. In all cases, the deposition rates rescaled by the friction velocity range from 10 -3 to a wind speed of 1 m/s to 10 -5 - 10 -4 for wind speeds above 5 m/s. It is shown that the changing speed rescaled is inversely proportional to the wind velocity when the water surface is smooth (between 1 and 5 m/s ) and becomes proportional to the deformation when the surface becomes significant (over 5 m/s ). Although the results do not clearly identify the effect of the current on the deposition velocity, the modeling shows that turbulent diffusion is dominant in

  10. Dry deposition of submicron atmospheric aerosol over water surfaces in motion

    International Nuclear Information System (INIS)

    Nevenick, Calec

    2013-01-01

    conditions (central wind speed: 1, 2, 4, 5, 7.5 and 9.5 m/s), current (co - current and counter-current, water flow velocity: 0, 6 and 12 cm/s ), ambient (temperature and relative humidity of the air and water temperature), the liquid surface deformations (measured significant wave height) and size distribution of aerosols released. The modeling part was to adapt the model to resistance. Slinn and Slinn (1980). This model is based on the assumption of conservation of vertical flow in the boundary layer. This one is divided into two layers: a very thin deposition layer near the surface which is water-saturated and a transfer layer located above. The transfer layer provides the particle deposition layer by turbulent diffusion and sedimentation. In the deposition layer the particles are deposited under the effect of several mechanisms such as Brownian diffusion, sedimentation, impaction and phoretic mechanisms. The main adjustments made by this work have been to take specific account of the different classes of particle size distribution, the spectrum variation as a function of hygroscopicity, and mechanisms of aggregation. It is integrated mechanisms of diffusiophoresis and thermophoresis, respectively produced by the evaporation of water and the temperature gradient at the air-water interface. To account for hygroscopic uranine aerosols, the deposition rates are analyzed in terms of humidity and rescaled by the friction velocity. In all cases, the deposition rates rescaled by the friction velocity range from 10 -3 to a wind speed of 1 m/s to 10 -5 - 10 -4 for wind speeds above 5 m/s. It is shown that the changing speed rescaled is inversely proportional to the wind velocity when the water surface is smooth (between 1 and 5 m/s ) and becomes proportional to the deformation when the surface becomes significant (over 5 m/s ). Although the results do not clearly identify the effect of the current on the deposition velocity, the modeling shows that turbulent diffusion is dominant

  11. Urban increments of gaseous and aerosol pollutants and their sources using mobile aerosol mass spectrometry measurements

    Directory of Open Access Journals (Sweden)

    M. Elser

    2016-06-01

    Full Text Available Air pollution is one of the main environmental concerns in urban areas, where anthropogenic emissions strongly affect air quality. This work presents the first spatially resolved detailed characterization of PM2.5 (particulate matter with aerodynamic equivalent diameter daero  ≤  2.5 µm in two major Estonian cities, Tallinn and Tartu. The measurements were performed in March 2014 using a mobile platform. In both cities, the non-refractory (NR-PM2.5 was characterized by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS using a recently developed lens which increases the transmission of super-micron particles. Equivalent black carbon (eBC and several trace gases including carbon monoxide (CO, carbon dioxide (CO2, and methane (CH4 were also measured. The chemical composition of PM2.5 was found to be very similar in the two cities. Organic aerosol (OA constituted the largest fraction, explaining on average about 52 to 60 % of the PM2.5 mass. Four sources of OA were identified using positive matrix factorization (PMF: hydrocarbon-like OA (HOA, from traffic emissions, biomass burning OA (BBOA, from biomass combustion, residential influenced OA (RIOA, probably mostly from cooking processes with possible contributions from waste and coal burning, and oxygenated OA (OOA, related to secondary aerosol formation. OOA was the major OA source during nighttime, explaining on average half of the OA mass, while during daytime mobile measurements the OA was affected by point sources and dominated by the primary fraction. A strong increase in the secondary organic and inorganic components was observed during periods with transport of air masses from northern Germany, while the primary local emissions accumulated during periods with temperature inversions. Mobile measurements offered the identification of different source regions within the urban areas and the assessment of the extent to which pollutants concentrations exceeded

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

    Energy Technology Data Exchange (ETDEWEB)

    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 layers are also discussed.

  13. Aerosol optical properties and direct radiative forcing based on measurements from the China Aerosol Remote Sensing Network (CARSNET) in eastern China

    Science.gov (United States)

    Che, Huizheng; Qi, Bing; Zhao, Hujia; Xia, Xiangao; Eck, Thomas F.; Goloub, Philippe; Dubovik, Oleg; Estelles, Victor; Cuevas-Agulló, Emilio; Blarel, Luc; Wu, Yunfei; Zhu, Jun; Du, Rongguang; Wang, Yaqiang; Wang, Hong; Gui, Ke; Yu, Jie; Zheng, Yu; Sun, Tianze; Chen, Quanliang; Shi, Guangyu; Zhang, Xiaoye

    2018-01-01

    Aerosol pollution in eastern China is an unfortunate consequence of the region's rapid economic and industrial growth. Here, sun photometer measurements from seven sites in the Yangtze River Delta (YRD) from 2011 to 2015 were used to characterize the climatology of aerosol microphysical and optical properties, calculate direct aerosol radiative forcing (DARF) and classify the aerosols based on size and absorption. Bimodal size distributions were found throughout the year, but larger volumes and effective radii of fine-mode particles occurred in June and September due to hygroscopic growth and/or cloud processing. Increases in the fine-mode particles in June and September caused AOD440 nm > 1.00 at most sites, and annual mean AOD440 nm values of 0.71-0.76 were found at the urban sites and 0.68 at the rural site. Unlike northern China, the AOD440 nm was lower in July and August (˜ 0.40-0.60) than in January and February (0.71-0.89) due to particle dispersion associated with subtropical anticyclones in summer. Low volumes and large bandwidths of both fine-mode and coarse-mode aerosol size distributions occurred in July and August because of biomass burning. Single-scattering albedos at 440 nm (SSA440 nm) from 0.91 to 0.94 indicated particles with relatively strong to moderate absorption. Strongly absorbing particles from biomass burning with a significant SSA wavelength dependence were found in July and August at most sites, while coarse particles in March to May were mineral dust. Absorbing aerosols were distributed more or less homogeneously throughout the region with absorption aerosol optical depths at 440 nm ˜ 0.04-0.06, but inter-site differences in the absorption Angström exponent indicate a degree of spatial heterogeneity in particle composition. The annual mean DARF was -93 ± 44 to -79 ± 39 W m-2 at the Earth's surface and ˜ -40 W m-2 at the top of the atmosphere (for the solar zenith angle range of 50 to 80°) under cloud-free conditions. The fine mode

  14. The theory of the interaction of atmospheric aerosol with underlying surface

    International Nuclear Information System (INIS)

    Buikov, M.V.

    1993-01-01

    The interaction of wind with underlying surfaces through resuspension makes a great contribution to the total amount of atmospheric aerosols. The dry deposition process results in cleaning of the atmosphere and contamination of near-surface air layers of soil and vegetation. This paper examines the theory leading to an exact solution of the problem of turbulent transportation of pollution taking into account resuspension and dry-deposition. This may be useful for the interpretation of observational data and for the improvement of calculation methods to describe aerosol exchange at surfaces in air. (author)

  15. Aerosol/Cloud Measurements Using Coherent Wind Doppler Lidars

    Directory of Open Access Journals (Sweden)

    Royer Philippe

    2016-01-01

    LEOSPHERE has recently developed aerosol/cloud detection and characterization on WINDCUBE long range Coherent Wind Doppler Lidars (CWDL. These new features combine wind and backscatter intensity informations (Carrier-to-Noise Ratio CNR in order to detect (aerosol/cloud base and top, PBL height and to characterize atmospheric structures (attenuated backscatter, depolarization ratio. For each aerosol/cloud functionality the method is described, limitations are discussed and examples are given to illustrate the performances.

  16. Urban aerosol hygroscopicity and CCN activity measured during the MAPS-Seoul 2016 campaign

    Science.gov (United States)

    Kim, N.; Park, M.; Yum, S. S.; Kim, D. S.

    2016-12-01

    While submicron aerosols in atmosphere and their effects on air quality and climate are a rising issue in atmospheric sciences, scientific understanding of them is still limited due to the lack of comprehensive observations. In particular, studies for hygroscopic properties of aerosols, closely related to cloud condensation nuclei (CCN) activity, are essential to aerosol-cloud-interaction study as aerosols can act as CCN, which crucially influence cloud microphysical and radiative properties. Urban aerosol properties were measured at Olympic Park in Seoul, a typical megacity with various anthropogenic sources, during the Megacity Air Pollution Studies (MAPS-Seoul 2016) campaign (9 May- 12 June 2016) for understanding diverse aspects of air quality problem in Korea. Physical properties of aerosols, including aerosol and CCN number concentration, aerosol size distribution and growth factor were measured by CPC, CCNC, SMPS and H-TDMA, respectively. Simultaneously, size-resolved chemical component of aerosol and water-soluble aerosol mass concentration were measured by AMS and PILS-IC. These measurement data are used for comprehensive analysis. A main focus will be on the relationship between overall properties of aerosols and their CCN activity in urban area. Results from MAPS-Seoul 2015 will also be used as reference for comparison with measurements in 2016 campaign. For example, aerosol number concentrations peaked at 0800, 1500 and 2000 LT due to traffic at rush hours and photochemical reaction in the afternoon. This is slightly different from the results of MAPS-Seoul 2015 campaign that showed two dominant peaks in the morning and afternoon.

  17. SAFARI 2000 Atmospheric Aerosol Measurements, Hand-held Hazemeters, Zambia

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: In conjunction with the AERONET (AErosol RObotic NETwork) participation in SAFARI 2000, the USDA Forest Service deployed handheld hazemeters in western...

  18. Adsorption and revaporisation studies of thin iodine oxide and CsI aerosol deposits from containment surface materials in LWRs

    Energy Technology Data Exchange (ETDEWEB)

    Tietze, S.; Foreman, M.; Ekberg, C. [Chalmers Univ. of Technology, Goeteborg (Sweden); Kaerkelae, T.; Auvinen, A.; Tapper, U.; Jokiniemi, J. [VTT Technical Research Centre of Finland, Espoo (Finland)

    2013-07-15

    During a severe nuclear accident released fission and radiolysis products can react with each other to form new species which might contribute to the volatile source term. Iodine will be released from UO2 fuel mainly in form as CsI aerosol particles and elemental iodine. Elemental iodine can react in gaseous phase with ozone to form solid iodine oxide aerosol particles (IOx). Within the AIAS-2 (Adsorption of Iodine Aerosols on Surfaces) project the interactions of IOx and CsI aerosols with common containment surface materials was investigated. Common surface materials in Swedish and Finnish LWRs are Teknopox Aqua V A paint films and metal surfaces such as Cu, Zn, Al and SS. Non-radioactive and {sup 131}I labelled aerosols were produced from a KI solution and ozone with a new facility designed and built at VTT Technical Research Centre of Finland. CsI aerosols were produced from a CsI solution with the same facility. A monolayer of the aerosols was deposited on the surfaces. The deposits were analysed with microscopic and spectroscopic measurement techniques to identify the chemical form of the deposits on the surfaces to identify if a chemical conversion on the different surface materials had occured. The revaporisation behaviour of the deposited aerosol particles from the different surface materials was studied under the influence of heat, humidity and gamma irradiation at Chalmers University of Technology, Sweden. Studies on the effects of humidity were performed using the FOMICAG facility, while heat and irradiation experiments were performed in a thermostated heating block and with a gammacell 22 with a dose rate of 14 kGy/h. The revaporisation losses were measured using a HPGe detector. The decomposition effect of the radiolysis product carbon monoxide was tested on IOx aerosols deposited on a glass fibre filter. Iodine oxide particles were produced at 50 deg. C, 100 deg. C and 120 deg. C and deposited on filter samples in order to study the chemical

  19. Measurement of the electrostatic charge in airborne particles: II - particle charge distribution of different aerosols

    Directory of Open Access Journals (Sweden)

    M. V. Rodrigues

    2006-03-01

    Full Text Available This work gives sequence to the study on the measurement of the electrostatic charges in aerosols. The particle charge classifier developed for this purpose and presented in the previous paper (Marra and Coury, 2000 has been used here to measure the particle charge distribution of a number of different aerosols. The charges acquired by the particles were naturally derived from the aerosol generation procedure itself. Two types of aerosol generators were used: the vibrating orifice generator and turntable Venturi plate generator. In the vibrating orifice generator, mono-dispersed particles were generated by a solution of water/ethanol/methylene blue, while in the rotating plate generator, six different materials were utilized. The results showed no clear dependence between electric charge and particle diameter for the mono-dispersed aerosol. However, for the poly-dispersed aerosols, a linear dependence between particle size and charge could be noticed.

  20. Aerosol Profile Measurements from the NASA Langley Research Center Airborne High Spectral Resolution Lidar

    Science.gov (United States)

    Obland, Michael D.; Hostetler, Chris A.; Ferrare, Richard A.; Hair, John W.; Roers, Raymond R.; Burton, Sharon P.; Cook, Anthony L.; Harper, David B.

    2008-01-01

    Since achieving first light in December of 2005, the NASA Langley Research Center (LaRC) Airborne High Spectral Resolution Lidar (HSRL) has been involved in seven field campaigns, accumulating over 450 hours of science data across more than 120 flights. Data from the instrument have been used in a variety of studies including validation and comparison with the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite mission, aerosol property retrievals combining passive and active instrument measurements, aerosol type identification, aerosol-cloud interactions, and cloud top and planetary boundary layer (PBL) height determinations. Measurements and lessons learned from the HSRL are leading towards next-generation HSRL instrument designs that will enable even further studies of aerosol intensive and extensive parameters and the effects of aerosols on the climate system. This paper will highlight several of the areas in which the NASA Airborne HSRL is making contributions to climate science.

  1. Measurements of trace gas species and aerosols at three Siberian stations

    Science.gov (United States)

    Arshinov, Mikhail Yu.; Belan, Boris D.; Davydov, Denis K.; Kozlov, Artem V.; Ivlev, Georgii A.; Pestunov, Dmitrii A.; Tolmachev, Gennadii N.; Fofonov, Alexander V.

    2014-05-01

    Siberia is of great importance to understand the climate change due to it covers about 10% of Earth's land surface and it has the largest area to be studied under the Pan-Eurasian Experiment (PEEX). In the overview done by Kulmala et al. (2011) authors arrived at a conclusion that continuous and comprehensive measurements of GHGs and aerosols over Siberia are still lacking. Understanding the importance of this problem, in recent years the Institute of Atmospheric Optics SB RAS established several monitoring stations for continuous measurements of aerosol and trace gas species to fill up this gap. In this paper we present some results of continuous measurements of trace gas species and aerosols carried out at three stations located in West Siberia. The first one is a so-called TOR-station located in the scientific campus of Tomsk (56° 28'41"N, 85° 03'15"E), the second one is the Base Experimental Complex (BEC, 56° 28'49"N, 85° 06'08"E) - in the eastern suburbs of Tomsk, and the third one is Fonovaya Observatory (56° 25'07"N, 84° 04'27"E) - in a rural area 60 km west of Tomsk. All equipment of the stations is fully automated and can be monitored via Internet. Gas analyzers are hourly calibrated against standard gas mixtures, micro-flux gas sources, or gas generators, depending on the instrument type and the gas to be detected. Aerosol measurements carried out continuously from March 2010 enabled a frequency and seasonal dependency of the new particle formation (NPF) events to be revealed. NPF events in Siberia are more often observed during spring (from March to May) and early autumn (secondary frequency peak in September). On average, NPF evens took place on 23-28 % of all days. This work was funded by Presidium of RAS (Program No. 4), Brunch of Geology, Geophysics and Mining Sciences of RAS (Program No. 5), Interdisciplinary integration projects of Siberian Branch of RAS (No. 35, No. 70, No. 131), Russian Foundation for Basic Research (grants No 14

  2. Aerosol single scattering albedo estimated across China from a combination of ground and satellite measurements

    Science.gov (United States)

    Kwon Ho Lee; Zhanqing Li; Man Sing Wong; Jinyuan Xin; Wang Yuesi; Wei Min Hao; Fengsheng Zhao

    2007-01-01

    Single scattering albedo (SSA) governs the strength of aerosols in absorbing solar radiation, but few methods are available to directly measure this important quantity. There currently exist many ground-based measurements of spectral transmittance from which aerosol optical thickness (AOT) are retrieved under clear sky conditions. Reflected radiances at the top of the...

  3. Measurement of air aerosol size during the 2001/2002 harmattan ...

    African Journals Online (AJOL)

    The measurement of air aerosol size during the 2001/2002 harmattan season at Uturu, Nigeria is of interest. Aerosol size distributions were measured making use of a zeiss micrometer which is inserted on the diaphragm inside the eyepiece of Olympus binocular microscope. Dust samples collected by direct deposition ...

  4. Aerosol counterflow two-jets unit for continuous measurement of the soluble fraction of atmospheric aerosols

    Czech Academy of Sciences Publication Activity Database

    Mikuška, Pavel; Večeřa, Zbyněk

    2005-01-01

    Roč. 77, č. 17 (2005), s. 5534-5541 ISSN 0003-2700 R&D Projects: GA ČR GA526/03/1182; GA ČR GA525/04/0011; GA AV ČR IAA4031105 Institutional research plan: CEZ:AV0Z40310501 Keywords : aerosol collector * atmospheric aerosols * continuous sampling Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 5.635, year: 2005

  5. Visibility of distant mountains as a measure of background aerosol pollution.

    Science.gov (United States)

    Porch, W M; Ensor, D S; Charlson, R J

    1975-02-01

    A relationship is developed between the visibility of distant mountains seen from an aircraft and a level of background aerosol pollution for a model atmosphere. It is found that the distance at which Mt. Rainier can be seen on clean-air days, which are typical of background aerosol levels, is consistent with the level of aerosol light-scattering measurements in other background situations.

  6. The Aerosol Models in MODTRAN: Incorporating Selected Measurements From Northern Australia

    Science.gov (United States)

    2005-12-01

    of atmospheric aerosol obtained around Jabiru , N.T., in June and September 2003. These measurements are used to obtain theoretical multimode size...coefficients. The attenuation coefficients are then incorporated into MODTRAN and compared with the default aerosol models. Finally the Jabiru aerosol is...centred on Jabiru in the Northern Territory, Australia. This environment is typical of a Northern Australian dry season climate. Atmospheric transmission

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

    Science.gov (United States)

    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.

  8. Tools for measuring surface cleanliness

    Energy Technology Data Exchange (ETDEWEB)

    Schroder, Mark Stewart (Hendersonville, NC); Woodmansee, Donald Ernest (Simpsonville, SC); Beadie, Douglas Frank (Greenville, SC)

    2002-01-01

    A procedure and tools for quantifying surface cleanliness are described. Cleanliness of a target surface is quantified by wiping a prescribed area of the surface with a flexible, bright white cloth swatch, preferably mounted on a special tool. The cloth picks up a substantial amount of any particulate surface contamination. The amount of contamination is determined by measuring the reflectivity loss of the cloth before and after wiping on the contaminated system and comparing that loss to a previous calibration with similar contamination. In the alternative, a visual comparison of the contaminated cloth to a contamination key provides an indication of the surface cleanliness.

  9. Effect of aerosols and NO2 concentration on ultraviolet actinic flux near Mexico City during MILAGRO: measurements and model calculations

    Energy Technology Data Exchange (ETDEWEB)

    Palancar, G. G.; Lefer, B. L.; Hall, S. R.; Shaw, W. J.; Corr, C. A.; Herndon, S. C.; Slusser, J. R.; Madronich, S.

    2013-01-24

    Ultraviolet (UV) actinic fluxes (AF) measured with three Scanning Actinic Flux Spectroradiometers (SAFS) are compared with the Tropospheric Ultraviolet-Visible (TUV) model v.5 in order to assess the effects of aerosols and NO2 concentrations on the radiation. Measurements were made during the MILAGRO campaign near Mexico City in March 2006, at a ground-based station near Mexico City (the T1 supersite) and from the NSF/NCAR C-130 aircraft. At the surface, measurements are typically smaller by up to 25 % in the morning, 10% at noon, and 40% in the afternoon, than actinic flux modeled for clean, cloud-free conditions. When measurements of PBL height, NO2 concentration and aerosols optical properties are included in the model, the agreement improves to within ±10% in the morning and afternoon, and ±3% at noon. Based on daily averages, aerosols account for 68%, NO2 for 25%, and residual uncertainties for 7% of these AF reductions observed at the surface. Several overpasses from the C-130 aircraft provided the opportunity to examine the actinic flux perturbations aloft, and also show better agreement with the model when aerosol and NO2 effects are included above and below the flight altitude. TUV model simulations show that the vertical structure of the actinic flux is sensitive to the choice of the aerosol single scattering albedo (SSA) at UV wavelengths. Typically, aerosols caused enhanced AF above the PBL and reduced AF near the surface. However, for highly scattering aerosols (SSA > 0.95), enhancements can penetrate well into the PBL, while for strongly absorbing aerosols (SSA<0.7) reductions in AF are computed in the free troposphere as well as in the PBL. Finally, additional measurements of the SSA at these wavelengths are needed to better constrain the effect of aerosols on the vertical structure of the actinic flux.

  10. Aerosol-Driven Surface Solar Dimming Over Asia: Insights from a Model-Observation Intercomparison

    Science.gov (United States)

    Persad, G.; Ming, Y.; Ramaswamy, V.

    2012-12-01

    Sun photometer and satellite data have indicated a reduction in surface solar radiation (SSR) over India and China during the second half of the 20th century that is at least partly due to anthropogenic aerosols. Recent integrated observational studies of aerosol properties also suggest that this SSR reduction may have a strong contribution from atmospheric absorption by carbonaceous aerosols over Asia. The reduction in SSR and associated redistribution of energy between the surface and atmosphere may have significant implications for regional hydrological systems like the summertime monsoon. Previous generations of general circulation models (GCMs), however, have been largely unsuccessful at recreating aerosol-driven trends in SSR, hindering theoretical investigation of causes and effects of these trends in regional climate. We analyze the behavior of SSR over Asia in the Geophysical Fluid Dynamics Laboratory's AM3 Atmospheric General Circulation Model—the updated aerosol treatment of which contains internal mixing of aerosols and interactive dry and wet deposition—in the context of new satellite and ground-based observational estimates of aerosol-driven SSR reduction. We find that AM3 is more successful than the previous generation of GCMs at recreating the observed SSR trend over South and East Asia and also suggests that as much as half of the clear-sky trend may be attributable to increases in atmospheric absorption in both regions. We will discuss the SSR and atmospheric absorption trends over China and India, as depicted in both observations and AM3, as well the particular aerosol processes responsible for the model's recreation of the trends and their implications for regional climate.

  11. Lidar and aerosol measurements over the surf zone

    NARCIS (Netherlands)

    Moerman, M.M.; Cohen, L.H.; Leeuw, G. de; Kunz, G.J.

    2001-01-01

    The aerosol produced by waves breaking in the surf zone is important for a variety of processes, such as transport of pollutants and bacteria, and electro optical propagation in the coastal zone. Yet, quantitative information on surf produced aerosol is very limited (de Leeuw et al., 2000). In the

  12. Atmospheric aerosol in an urban area: Comparison of measurement instruments and methodologies and pulmonary deposition assessment

    International Nuclear Information System (INIS)

    Berico, M.; Luciani, A.; Formignani, M.

    1996-07-01

    In March 1995 a measurement campaign of atmospheric aerosol in the Bologna urban area (Italy) was carried out. A transportable laboratory, set up by ENEA (Italian national Agency for New Technologies, Energy and the Environment) Environmental Department (Bologna), was utilized with instruments for measurement of atmospheric aerosol and meteorological parameters. The aim of this campaign was of dual purpose: to characterize aerosol in urban area and to compare different instruments and methodologies of measurements. Mass concentrations measurements, evaluated on a 23-hour period with total filter, PM10 dichotomous sampler and low pressure impactor (LPI Berner), have provided information respectively about total suspended particles, respirable fraction and granulometric parameters of aerosol. Eight meteorologic parameters, number concentration of submicromic fraction of aerosol and mass concentration of micromic fraction have been continually measured. Then, in a daytime period, several number granulometries of atmospheric aerosol have also been estimated by means of diffusion battery system. Results related to different measurement methodologies and granulometric characteristics of aerosol are presented here. Pulmonary deposition of atmospheric aerosol is finally calculated, using granulometries provided by LPI Brener and ICRP 66 human respiratory tract model

  13. Retrieval of stratospheric aerosol distributions from SCIAMACHY limb measurements: methodology and first results

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, Florian; Savigny, Christian von; Rozanov, Alexei; Rozanov, Vladimir; Bovensmann, Heinrich; Burrows, John [Institute for Environmental Physics, University of Bremen (Germany)

    2010-07-01

    Stratospheric aerosols play an important role for the global radiation budget and for trace gas retrievals, especially ozone. SAGE I to III provided a 25-year record of stratospheric aerosols by means of solar occultation technique. Since the demise of SAGE II and III in 2005/2006, no instrument with this technique provides a continuation of this data set. Goal of this work is to demonstrate that aerosol extinction profiles can be retrieved from SCIAMACHY limb scatter measurements to sustain the time series. Since the eruption of Pinatubo in 1991 was the last large source of volcanic aerosols in the stratosphere, we have now the opportunity to retrieve background aerosol profiles. The radiative transfer model SCIATRAN is used to derive aerosol extinction profiles for SCIAMACHY limb data. The algorithm, sensitivity studies and first results are presented here.

  14. Armor Plate Surface Roughness Measurements

    National Research Council Canada - National Science Library

    Stanton, Brian; Coburn, William; Pizzillo, Thomas J

    2005-01-01

    ...., surface texture and coatings) that could become important at high frequency. We measure waviness and roughness of various plates to know the parameter range for smooth aluminum and rolled homogenous armor (RHA...

  15. Quantifying Above-Cloud Aerosols through Integrating Multi-Sensor Measurements from A-Train Satellites

    Science.gov (United States)

    Zhang, Yan

    2012-01-01

    Quantifying above-cloud aerosols can help improve the assessment of aerosol intercontinental transport and climate impacts. Large-scale measurements of aerosol above low-level clouds had been generally unexplored until very recently when CALIPSO lidar started to acquire aerosol and cloud profiles in June 2006. Despite CALIPSO s unique capability of measuring above-cloud aerosol optical depth (AOD), such observations are substantially limited in spatial coverage because of the lidar s near-zero swath. We developed an approach that integrates measurements from A-Train satellite sensors (including CALIPSO lidar, OMI, and MODIS) to extend CALIPSO above-cloud AOD observations to substantially larger areas. We first examine relationships between collocated CALIPSO above-cloud AOD and OMI absorbing aerosol index (AI, a qualitative measure of AOD for elevated dust and smoke aerosol) as a function of MODIS cloud optical depth (COD) by using 8-month data in the Saharan dust outflow and southwest African smoke outflow regions. The analysis shows that for a given cloud albedo, above-cloud AOD correlates positively with AI in a linear manner. We then apply the derived relationships with MODIS COD and OMI AI measurements to derive above-cloud AOD over the whole outflow regions. In this talk, we will present spatial and day-to-day variations of the above-cloud AOD and the estimated direct radiative forcing by the above-cloud aerosols.

  16. Calculation of color difference and measurement of the spectrum of aerosol based on human visual system

    Science.gov (United States)

    Dai, Mengyan; Liu, Jianghai; Cui, Jianlin; Chen, Chunsheng; Jia, Peng

    2017-10-01

    In order to solve the problem of the quantitative test of spectrum and color of aerosol, the measurement method of spectrum of aerosol based on human visual system was proposed. The spectrum characteristics and color parameters of three different aerosols were tested, and the color differences were calculated according to the CIE1976-L*a*b* color difference formula. Three tested powders (No 1# No 2# and No 3# ) were dispersed in a plexglass box and turned into aerosol. The powder sample was released by an injector with different dosages in each experiment. The spectrum and color of aerosol were measured by the PRO 6500 Fiber Optic Spectrometer. The experimental results showed that the extinction performance of aerosol became stronger and stronger with the increase of concentration of aerosol. While the chromaticity value differences of aerosols in the experiment were so small, luminance was verified to be the main influence factor of human eye visual perception and contributed most in the three factors of the color difference calculation. The extinction effect of No 3# aerosol was the strongest of all and caused the biggest change of luminance and color difference which would arouse the strongest human visual perception. According to the sensation level of chromatic color by Chinese, recognition color difference would be produced when the dosage of No 1# powder was more than 0.10 gram, the dosage of No 2# powder was more than 0.15 gram, and the dosage of No 3# powder was more than 0.05 gram.

  17. Measurement-based aerosol forcing calculations: The influence of model complexity

    Directory of Open Access Journals (Sweden)

    Manfred Wendisch

    2001-03-01

    Full Text Available On the basis of ground-based microphysical and chemical aerosol measurements a simple 'two-layer-single-wavelength' and a complex 'multiple-layer-multiple-wavelength' radiative transfer model are used to calculate the local solar radiative forcing of black carbon (BC and (NH42SO4 (ammonium sulfate particles and mixtures (external and internal of both materials. The focal points of our approach are (a that the radiative forcing calculations are based on detailed aerosol measurements with special emphasis of particle absorption, and (b the results of the radiative forcing calculations with two different types of models (with regards to model complexity are compared using identical input data. The sensitivity of the radiative forcing due to key input parameters (type of particle mixture, particle growth due to humidity, surface albedo, solar zenith angle, boundary layer height is investigated. It is shown that the model results for external particle mixtures (wet and dry only slightly differ from those of the corresponding internal mixture. This conclusion is valid for the results of both model types and for both surface albedo scenarios considered (grass and snow. Furthermore, it is concluded that the results of the two model types approximately agree if it is assumed that the aerosol particles are composed of pure BC. As soon as a mainly scattering substance is included alone or in (internal or external mixture with BC, the differences between the radiative forcings of both models become significant. This discrepancy results from neglecting multiple scattering effects in the simple radiative transfer model.

  18. Confinement of surface waves at the air-water interface to control aerosol size and dispersity

    Science.gov (United States)

    Nazarzadeh, Elijah; Wilson, Rab; King, Xi; Reboud, Julien; Tassieri, Manlio; Cooper, Jonathan M.

    2017-11-01

    The precise control over the size and dispersity of droplets, produced within aerosols, is of great interest across many manufacturing, food, cosmetic, and medical industries. Amongst these applications, the delivery of new classes of high value drugs to the lungs has recently attracted significant attention from pharmaceutical companies. This is commonly achieved through the mechanical excitation of surface waves at the air liquid interface of a parent liquid volume. Previous studies have established a correlation between the wavelength on the surface of liquid and the final aerosol size. In this work, we show that the droplet size distribution of aerosols can be controlled by constraining the liquid inside micron-sized cavities and coupling surface acoustic waves into different volumes of liquid inside micro-grids. In particular, we show that by reducing the characteristic physical confinement size (i.e., either the initial liquid volume or the cavities' diameters), higher harmonics of capillary waves are revealed with a consequent reduction of both aerosol mean size and dispersity. In doing so, we provide a new method for the generation and fine control of aerosols' sizes distribution.

  19. A technique for rapid source apportionment applied to ambient organic aerosol measurements from a thermal desorption aerosol gas chromatograph (TAG

    Directory of Open Access Journals (Sweden)

    Y. Zhang

    2016-11-01

    Full Text Available We present a rapid method for apportioning the sources of atmospheric organic aerosol composition measured by gas chromatography–mass spectrometry methods. Here, we specifically apply this new analysis method to data acquired on a thermal desorption aerosol gas chromatograph (TAG system. Gas chromatograms are divided by retention time into evenly spaced bins, within which the mass spectra are summed. A previous chromatogram binning method was introduced for the purpose of chromatogram structure deconvolution (e.g., major compound classes (Zhang et al., 2014. Here we extend the method development for the specific purpose of determining aerosol samples' sources. Chromatogram bins are arranged into an input data matrix for positive matrix factorization (PMF, where the sample number is the row dimension and the mass-spectra-resolved eluting time intervals (bins are the column dimension. Then two-dimensional PMF can effectively do three-dimensional factorization on the three-dimensional TAG mass spectra data. The retention time shift of the chromatogram is corrected by applying the median values of the different peaks' shifts. Bin width affects chemical resolution but does not affect PMF retrieval of the sources' time variations for low-factor solutions. A bin width smaller than the maximum retention shift among all samples requires retention time shift correction. A six-factor PMF comparison among aerosol mass spectrometry (AMS, TAG binning, and conventional TAG compound integration methods shows that the TAG binning method performs similarly to the integration method. However, the new binning method incorporates the entirety of the data set and requires significantly less pre-processing of the data than conventional single compound identification and integration. In addition, while a fraction of the most oxygenated aerosol does not elute through an underivatized TAG analysis, the TAG binning method does have the ability to achieve molecular level

  20. Aerosol source apportionment from 1-year measurements at the CESAR tower in Cabauw, the Netherlands

    NARCIS (Netherlands)

    Schlag, Patrick; Kiendler-Scharr, Astrid; Blom, Marcus Johannes; Canonaco, Francesco; Henzing, Jeroen Sebastiaan; Moerman, Marcel; Prevot, Andre Stephan Henry; Holzinger, Rupert

    2016-01-01

    Intensive measurements of submicron aerosol particles and their chemical composition were performed with an Aerosol Chemical Speciation Monitor (ACSM) at the Cabauw Experimental Site for Atmospheric Research (CESAR) in Cabauw, the Netherlands, sampling at 5 m height above ground. The campaign lasted

  1. Constraining Aerosol Forcing from the Land Surface Temperature Record

    Science.gov (United States)

    Shen, Z.; Ming, Y.; Held, I.

    2017-12-01

    Understanding the anthropogenic influence on regional climate change is important for policy making and adaption planning. Atmosphere/land global climate models (AGCMs) with prescribed oceanic boundary conditions allow a decomposition of historical climate change into a fast component that occurs on an atmospheric adjustment time scale of a month or less, and a slow component due to the changing ocean and sea ice. These two components are simultaneously present in comprehensive coupled climate models. The slow component contains much of the uncertainty in climate sensitivity and is where the forced signals are mixed most strongly with natural variability. Here we use AGCMs to investigate the fast component of the anthropogenic influence on regional temperature change. Although this fast component of the anthropogenic warming is often thought of as small, we find that it is detectable in the observed warming of Northern Hemisphere land during the warm season in recent decades. We suggest that the fast response to aerosol forcing in isolation can be detected on subcontinental scales, and that AGCM simulations of the fast response are useful for empirically constraining aerosol forcing.

  2. Elemental composition of Arctic soils and aerosols in Ny-Ålesund measured using laser-induced breakdown spectroscopy

    Science.gov (United States)

    Kim, Gibaek; Yoon, Young-Jun; Kim, Hyun-A.; Cho, Hee-joo; Park, Kihong

    2017-08-01

    Two laser-induced breakdown spectroscopy (LIBS) systems (soil LIBS and aerosol LIBS) were used to determine the elemental composition of soils and ambient aerosols less than 2.5 μm in Ny-Ålesund, Svalbard (the world's most northerly human settlement). For soil LIBS measurements, matrix effects such as moisture content, soil grain size, and surrounding gas on the LIBS response were minimized. When Ar gas was supplied onto the soil sample surfaces, a significant enhancement in LIBS emission lines was observed. Arctic soil samples were collected at 10 locations, and various elements (Al, Ba, C, Ca, Cu, Fe, H, K, Mg, Mn, N, Na, O, Pb, and Si) were detected in soils. The elemental distribution in arctic soils was clearly distinguishable from those in urban and abandoned mining soils in Korea. Moreover, the concentrations of most of anthropogenic metals were fairly low, and localized sources in extremely close proximity affected the elevated level of Cu in the soil samples derived from Ny-Ålesund. The number of elements detected in aerosols (C, Ca, H, K, Mg, Na, and O) was lower than those determined in soils. The elements in aerosols can mainly originate from minerals and sea salts. The elemental distribution in aerosols was also clearly distinguishable from that in soils, suggesting that the resuspension of local soil particles by wind erosion into aerosols was minimal. The daily variation of particle number concentration (RSD = 71%) and the elements in aerosols (RSD = 25%) varied substantially, possibly due to fluctuating air masses and meteorological conditions.

  3. Impacts of dust aerosol and adjacency effects on the accuracy of Landsat 8 and RapidEye surface reflectances

    KAUST Repository

    Houborg, Rasmus

    2017-03-29

    The atmospheric correction of satellite data is challenging over desert agricultural systems, due to the relatively high aerosol optical thicknesses (τ550), bright soils, and a heterogeneous surface reflectance field. Indeed, the contribution of reflected radiation from adjacent pixels scattered into the field of view of a target pixel is considerable and can significantly affect the fidelity of retrieved reflectances. In this study, uncertainties and quantitative errors associated with the atmospheric correction of multi-spectral Landsat 8 and RapidEye data were characterized over a desert agricultural landscape in Saudi Arabia. Surface reflectances were retrieved using an implementation of the 6SV atmospheric correction code, and validated against field collected spectroradiometer measurements over desert, cultivated soil, and vegetated surface targets. A combination of satellite and Aerosol Robotic Network (AERONET) data were used to parameterize aerosol properties and atmospheric state parameters. With optimal specification of τ550 and aerosol optical properties and correction for adjacency effects, the relative Mean Absolute Deviation (MAD) for all bands combined was 5.4% for RapidEye and 6.8% for Landsat 8. However uncertainties associated with satellite-based τ550 retrievals were shown to introduce significant error into the reflectance estimates. With respect to deriving common vegetation indices from corrected reflectance data, the Normalized Difference Vegetation Index (NDVI) was associated with the smallest errors (3–8% MAD). Surface reflectance errors were highest for bands in the visible part of the spectrum, particularly the blue band (5–16%), while there was more consistency within the red-edge (~ 5%) and near-infrared (5–7%). Results were generally better constrained when a τ550-dependent aerosol model for desert dust particles, parameterized on the basis of nearby AERONET site data, was used in place of a generic rural or background

  4. Retrieving aerosol height from the oxygen A band: a fast forward operator and sensitivity study concerning spectral resolution, instrumental noise, and surface inhomogeneity

    Science.gov (United States)

    Hollstein, A.; Fischer, J.

    2014-05-01

    Hyperspectral radiance measurements in the oxygen A band are sensitive to the vertical distribution of atmospheric scatterers, which in principle allows the retrieval of aerosol height from future instruments like TROPOMI, OCO2, FLEX, and CarbonSat. Discussed in this paper is a fast and flexible forward operator for the simulation of hyperspectral radiances in the oxygen A band and, based on this scheme, a sensitivity study about the inversion quality of aerosol optical thickness, aerosol mean height, and aerosol type. The forward operator is based on a lookup table with efficient data compression based on principal component analysis. Linear interpolation and computation of partial derivatives is performed in the much smaller space of expansion coefficients rather than wavelength. Thus, this approach is computationally fast and, at the same time, memory efficient. The sensitivity study explores the impact of instrument design on the retrieval of aerosol optical thickness and aerosol height. Considered are signal to noise ratio, spectral resolution, and spectral sampling. Also taken into account are surface inhomogeneities and variations of the aerosol type.

  5. A GC-TCD method for measuring the liquid water mass of collected aerosols

    Science.gov (United States)

    Lee, Chung-Te; Chang, Shih-Yu

    This work presents a gas chromatographic method that uses a thermal conductivity detector (GC-TCD) to measure the liquid water mass (LWM) of collected aerosols. The method is a modification of the previously developed EA-TCD method (Journal of Aerosol Science 29, 827). A microcomputer was incorporated into the system to control the analytical procedures, improve the measurement precision, and make possible a continuous operation. To validate the method, the aerosol LWMs of NaCl, Na 2SO 4, NH 4NO 3, (NH 4) 2SO 4, NH 4Cl, and Na 2CO 3 were measured at room temperature under relative humidities (RHs) varying between 20% and 90%, in both humidifying and dehumidifying conditions. Estimates of aerosol LWMs for varying aerosol chemical compositions and RHs by various measurement methods and predictive models are comprehensively compared. The comparison shows that the GC-TCD measurements agree closely with those of the other methods. The GC-TCD measurements are closer to the ISORROPIA model predictions than those of the AIM2 model. Most notably, our method determines, for the first time, the hygroscopic behavior of Na 2CO 3 aerosol yielding the deliquescence relative humidity and crystallization relative humidity at 78% and 39% RH, respectively. The hygroscopic characteristics of various NaCl mole fractions in mixed NaCl-Na 2SO 4 aerosols, determined by GC-TCD, are used to show the discrepancy between the measurements and the model's prediction.

  6. Direct measurements of mass-specific optical cross sections of single-component aerosol mixtures.

    Science.gov (United States)

    Radney, James G; Ma, Xiaofei; Gillis, Keith A; Zachariah, Michael R; Hodges, Joseph T; Zangmeister, Christopher D

    2013-09-03

    The optical properties of atmospheric aerosols vary widely, being dependent upon particle composition, morphology, and mixing state. This diversity and complexity of aerosols motivates measurement techniques that can discriminate and quantify a variety of single- and multicomponent aerosols that are both internally and externally mixed. Here, we present a new combination of techniques to directly measure the mass-specific extinction and absorption cross sections of laboratory-generated aerosols that are relevant to atmospheric studies. Our approach employs a tandem differential mobility analyzer, an aerosol particle mass analyzer, cavity ring-down and photoacoustic spectrometers, and a condensation particle counter. This suite of instruments enables measurement of aerosol particle size, mass, extinction and absorption coefficients, and aerosol number density, respectively. Taken together, these observables yield the mass-specific extinction and absorption cross sections without the need to model particle morphology or account for sample collection artifacts. Here we demonstrate the technique in a set of case studies which involve complete separation of aerosol by charge, separation of an external mixture by mass, and discrimination between particle types by effective density and single-scattering albedo.

  7. SAFARI 2000 Atmospheric Aerosol Measurements, Hand-held Hazemeters, Zambia

    Data.gov (United States)

    National Aeronautics and Space Administration — In conjunction with the AERONET (AErosol RObotic NETwork) participation in SAFARI 2000, the USDA Forest Service deployed handheld hazemeters in western Zambia from...

  8. Comparison of mineral dust and droplet residuals measured with two single particle aerosol mass spectrometers

    Science.gov (United States)

    Wonaschütz, Anna; Ludwig, Wolfgang; Zawadowicz, Maria; Hiranuma, Naruki; Hitzenberger, Regina; Cziczo, Daniel; DeMott, Paul; Möhler, Ottmar

    2017-04-01

    Single Particle mass spectrometers are used to gain information on the chemical composition of individual aerosol particles, aerosol mixing state, and other valuable aerosol characteristics. During the Mass Spectrometry Intercomparison at the Fifth Ice Nucleation (FIN-01) Workshop, the new LAAPTOF single particle aerosol mass spectrometer (AeroMegt GmbH) was conducting simultaneous measurements together with the PALMS (Particle Analysis by Laser Mass Spectrometry) instrument. The aerosol particles were sampled from the AIDA chamber during ice cloud expansion experiments. Samples of mineral dust and ice droplet residuals were measured simultaneously. In this work, three expansion experiments are chosen for a comparison between the two mass spectrometers. A fuzzy clustering routine is used to group the spectra. Cluster centers describing the ensemble of particles are compared. First results show that while differences in the peak heights are likely due to the use of an amplifier in PALMS, cluster centers are comparable.

  9. Measurements of uptake coefficients for heterogeneous loss of HO2 onto submicron inorganic salt aerosols.

    Science.gov (United States)

    George, I J; Matthews, P S J; Whalley, L K; Brooks, B; Goddard, A; Baeza-Romero, M T; Heard, D E

    2013-08-21

    Laboratory studies were conducted to investigate the kinetics of HO2 radical uptake onto submicron inorganic salt aerosols. HO2 reactive uptake coefficients were measured at room temperature using an aerosol flow tube and the Fluorescence Assay by Gas Expansion (FAGE) technique that allowed for measurements to be conducted under atmospherically relevant HO2 concentrations ([HO2] = 10(8) to 10(9) molecule cm(-3)). The uptake coefficient for HO2 uptake onto dry inorganic salt aerosols was consistently below the detection limit (γ(HO2) atmospheric models (γ(HO2) = 0.1-1.0). Evidence is presented showing that the HO2 uptake coefficients onto aqueous salt aerosol particles are dependent both on the exposure time to the aerosol and on the HO2 concentration used.

  10. Biomass Burning Aerosol Absorption Measurements with MODIS Using the Critical Reflectance Method

    Science.gov (United States)

    Zhu, Li; Martins, Vanderlei J.; Remer, Lorraine A.

    2010-01-01

    This research uses the critical reflectance technique, a space-based remote sensing method, to measure the spatial distribution of aerosol absorption properties over land. Choosing two regions dominated by biomass burning aerosols, a series of sensitivity studies were undertaken to analyze the potential limitations of this method for the type of aerosol to be encountered in the selected study areas, and to show that the retrieved results are relatively insensitive to uncertainties in the assumptions used in the retrieval of smoke aerosol. The critical reflectance technique is then applied to Moderate Resolution Imaging Spectrometer (MODIS) data to retrieve the spectral aerosol single scattering albedo (SSA) in South African and South American 35 biomass burning events. The retrieved results were validated with collocated Aerosol Robotic Network (AERONET) retrievals. One standard deviation of mean MODIS retrievals match AERONET products to within 0.03, the magnitude of the AERONET uncertainty. The overlap of the two retrievals increases to 88%, allowing for measurement variance in the MODIS retrievals as well. The ensemble average of MODIS-derived SSA for the Amazon forest station is 0.92 at 670 nm, and 0.84-0.89 for the southern African savanna stations. The critical reflectance technique allows evaluation of the spatial variability of SSA, and shows that SSA in South America exhibits higher spatial variation than in South Africa. The accuracy of the retrieved aerosol SSA from MODIS data indicates that this product can help to better understand 44 how aerosols affect the regional and global climate.

  11. Measurements of aerosol particle dry deposition velocity using the relaxed eddy accumulation technique

    OpenAIRE

    Grönholm, Tiia; Aalto, Pasi P.; Hiltunen, Veijo; Rannik, Üllar; Rinne, Janne; Laakso, Lauri; Hyvönen, Saara; Vesala, Timo; Kulmala, Markku

    2011-01-01

    The continuous measurements of aerosol particle deposition velocity have been performed from January 2004 to January 2005 using a REA technique with dynamic deadband. We measured aerosol particle deposition velocity in the size range of 10–150 nanometer with 5–10 nanometer steps using differential mobility analyser for sizing. We were able to measure two size classes simultaneously. One size class was changed at one month intervals, another we kept constant at 30 nm to investigate the effect ...

  12. ACCENT-BIAFLUX workshop 2005, trace gas and aerosol flux measurement and techniques. Abstract book

    Energy Technology Data Exchange (ETDEWEB)

    Werner, A.; Soerensen, L.L. (eds.)

    2005-04-01

    The woorkshop trace gas and aerosol flux measurement techniques in the second meeting within the Biosphere Atmosphere Exchange of Pollutions (BIAFLUX) group in the EU-network project Atmospheric Composition Change (ACCENT). The goal of the workshop is to obtain an overview of techniques for measurements of gas and aerosol fluxes and to gather the knowledge of uncertainties in flux measurements and calculations. The workshop is funded by ACCENT. The abstract book presents abstracts of 21 oral presentations and 26 poster presentations. (LN)

  13. Aerosol measurements at 60 m during April 1994 remote cloud study intensive operating period (RCS/IOP)

    Energy Technology Data Exchange (ETDEWEB)

    Leifer, R.; Albert, B.; Lee, N.; Knuth, R.H. [Department of Energy, New York, NY (United States)] [and others

    1996-04-01

    Aerosol measurements were made at the Southern Great Plains Site of the Atmospheric Radiation Measurement (ARM) program. Many types of air masses pass over this area, and on the data acquisition day, extremly low aerosol scattering coefficients were seen. A major effort was placed on providing some characterization of the aerosol size distribution. Data is currently available from the experimental center.

  14. A Comparison of Aerosol Optical Property Measurements Made During the DOE Aerosol Intensive Operating Period and Their Effects on Regional Climate

    Science.gov (United States)

    Strawa, Anthony W.; Hallar, A. G.; Arnott, W. P.; Covert, D.; Elleman, R.; Ogren, J.; Schmid, B.; Luu, A.

    2004-01-01

    The amount of radiant energy an aerosol absorbs has profound effects on climate and air quality. It is ironic that aerosol absorption coefficient is one of the most difficult to measure aerosol properties. One of the main purposes of the DOE Aerosol Intensive Operating Period (IOP) flown in May, 2003 was to assess our ability to measure absorption coefficient in situ. This paper compares measurements of aerosol optical properties made during the IOP. Measurements of aerosol absorption coefficient were made by Particle Soot Absorption Photometer (PSAP) aboard the CIRPAS Twin-Otter (U. Washington) and on the DOE Cessna 172 (NOAA-C,MDL). Aerosol absorption coefficient was also measured by a photoacoustic instrument (DRI) that was operated on an aircraft for the first time during the IOP. A new cavity ring-down (CRD) instrument, called Cadenza (NASA-AkC), measures the aerosol extinction coefficient for 675 nm and 1550 nm light, and simultaneously measures the scattering coefficient at 675 nm. Absorption coefficient is obtained from the difference of measured extinction and scattering within the instrument. Measurements of absorption coefficient from all of these instruments during appropriate periods are compared. During the IOP, several significant aerosol layers were sampled aloft. These layers are identified in the remote (AATS-14) as well as in situ measurements. Extinction profiles measured by Cadenza are compared to those derived from the Ames Airborne Tracking Sunphotometer (AATS-14, NASA-ARC). The regional radiative impact of these layers is assessed by using the measured aerosol optical properties in a radiative transfer model.

  15. Aerosol Observing System (AOS) Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Jefferson, A

    2011-01-17

    The Aerosol Observing System (AOS) is a suite of in situ surface measurements of aerosol optical and cloud-forming properties. The instruments measure aerosol properties that influence the earth’s radiative balance. The primary optical measurements are those of the aerosol scattering and absorption coefficients as a function of particle size and radiation wavelength and cloud condensation nuclei (CCN) measurements as a function of percent supersaturation. Additional measurements include those of the particle number concentration and scattering hygroscopic growth. Aerosol optical measurements are useful for calculating parameters used in radiative forcing calculations such as the aerosol single-scattering albedo, asymmetry parameter, mass scattering efficiency, and hygroscopic growth. CCN measurements are important in cloud microphysical models to predict droplet formation.

  16. Characterization of a real-time tracer for isoprene epoxydiols-derived secondary organic aerosol (IEPOX-SOA) from aerosol mass spectrometer measurements

    OpenAIRE

    Hu, W. W.; St. Clair, J. M.

    2015-01-01

    Substantial amounts of secondary organic aerosol (SOA) can be formed from isoprene epoxydiols (IEPOX), which are oxidation products of isoprene mainly under low-NO conditions. Total IEPOX-SOA, which may include SOA formed from other parallel isoprene oxidation pathways, was quantified by applying positive matrix factorization (PMF) to aerosol mass spectrometer (AMS) measurements. The IEPOX-SOA fractions of organic aerosol (OA) in multiple field studies across several continents are summarized...

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

    Science.gov (United States)

    Kaloshin, Gennady A.; Matvienko, Gennady G.

    2007-06-01

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

  18. Black carbon aerosols over the Himalayas: direct and surface albedo forcing

    Directory of Open Access Journals (Sweden)

    Vijayakumar S. Nair

    2013-09-01

    Full Text Available Absorbing aerosols such as black carbon (BC or dust over high-altitude Himalayan regions have potential implications on the regional climate and hydrological cycle over South Asia. Making use of extensive measurements of atmospheric BC from several Himalayan stations, an assessment of radiative forcing due to direct and snow-albedo darkening is examined. Generally, BC concentration in the atmosphere peaks during pre-monsoon season over the Himalayas and the climatological mean of atmospheric BC over Hanle (western Himalayas, 4.5 km msl and Nepal Climate Observatory-Pyramid (central Himalayas, 5 km msl are 106±27 ng m−3 and 190±95 ng m−3, respectively. Based on the optical and physical properties of composite aerosols measured at Hanle, clear sky direct radiative forcing (DRF at the top of the atmosphere is estimated as 1.69 W m−2 over snow surface and −1.54 W m−2 over sandy surface during pre-monsoon season. The estimated amount of BC in the snow varied from 117 to 1.7 µg kg−1 for wide range of dry deposition velocities (0.01–0.054 cm s−1 of BC, snow depth (2–10 cm and snow densities (195–512 kg m−3. Using a size-resolved wet scavenging parametrisation, the amount of BC on snow due to wet scavenging is estimated as 29 µg kg−1 for an accumulated snow depth of 27 cm. For the range of 10–200 µg kg−1 of BC in snow, the diurnally averaged forcing due to snow darkening has been found to vary from 0.87 to 10.2 W m−2 for fresh snow and from 2.6 to 28.1 W m−2 for the aged snow, which is significantly higher than the DRF. The direct and surface albedo radiative forcing could lead to significant warming over the Himalayas during pre-monsoon.

  19. NASA LaRC airborne high spectral resolution lidar aerosol measurements during MILAGRO: observations and validation

    Directory of Open Access Journals (Sweden)

    L. I. Kleinman

    2009-07-01

    Full Text Available The NASA Langley Research Center (LaRC airborne High Spectral Resolution Lidar (HSRL measures vertical profiles of aerosol extinction, backscatter, and depolarization at both 532 nm and 1064 nm. In March of 2006 the HSRL participated in the Megacity Initiative: Local and Global Research Observations (MILAGRO campaign along with several other suites of instruments deployed on both aircraft and ground based platforms. This paper presents high spatial and vertical resolution HSRL measurements of aerosol extinction and optical depth from MILAGRO and comparisons of those measurements with similar measurements from other sensors and model predictions. HSRL measurements coincident with airborne in situ aerosol scattering and absorption measurements from two different instrument suites on the C-130 and G-1 aircraft, airborne aerosol optical depth (AOD and extinction measurements from an airborne tracking sunphotometer on the J-31 aircraft, and AOD from a network of ground based Aerosol Robotic Network (AERONET sun photometers are presented as a validation of the HSRL aerosol extinction and optical depth products. Regarding the extinction validation, we find bias differences between HSRL and these instruments to be less than 3% (0.01 km−1 at 532 nm, the wavelength at which the HSRL technique is employed. The rms differences at 532 nm were less than 50% (0.015 km−1. To our knowledge this is the most comprehensive validation of the HSRL measurement of aerosol extinction and optical depth to date. The observed bias differences in ambient aerosol extinction between HSRL and other measurements is within 15–20% at visible wavelengths, found by previous studies to be the differences observed with current state-of-the-art instrumentation (Schmid et al., 2006.

  20. Atmospheric aerosol in an urban area: Comparison of measurement instruments and methodologies and pulmonary deposition assessment; Aerosol atmosferico in area urbanae di misura e valutazione di deposizione polmonare

    Energy Technology Data Exchange (ETDEWEB)

    Berico, M.; Luciani, A.; Formignani, M. [ENEA, Centro Ricerche Bologna (Italy). Dip. Ambiente

    1996-07-01

    In March 1995 a measurement campaign of atmospheric aerosol in the Bologna urban area (Italy) was carried out. A transportable laboratory, set up by ENEA (Italian national Agency for New Technologies, Energy and the Environment) Environmental Department (Bologna), was utilized with instruments for measurement of atmospheric aerosol and meteorological parameters. The aim of this campaign was of dual purpose: to characterize aerosol in urban area and to compare different instruments and methodologies of measurements. Mass concentrations measurements, evaluated on a 23-hour period with total filter, PM10 dichotomous sampler and low pressure impactor (LPI Berner), have provided information respectively about total suspended particles, respirable fraction and granulometric parameters of aerosol. Eight meteorologic parameters, number concentration of submicromic fraction of aerosol and mass concentration of micromic fraction have been continually measured. Then, in a daytime period, several number granulometries of atmospheric aerosol have also been estimated by means of diffusion battery system. Results related to different measurement methodologies and granulometric characteristics of aerosol are presented here. Pulmonary deposition of atmospheric aerosol is finally calculated, using granulometries provided by LPI Brener and ICRP 66 human respiratory tract model.

  1. In Situ Measurement of the Infrared Spectral Extinction for Various Chemical, Biological, and Background Aerosols

    National Research Council Canada - National Science Library

    Gurton, Kristan

    2003-01-01

    We conducted a series spectral extinction measurements on a variety of aerosolized chemical and biological simulants over the spectral range 3-13 microns using conventional Fourier transform infrared (FTIR...

  2. First measurements of aerosol optical depth and Angstrom exponent number from AERONET's Kuching site

    Science.gov (United States)

    Salinas, Santo V.; Chew, Boon N.; Mohamad, M.; Mahmud, M.; Liew, Soo C.

    2013-10-01

    We report our first measurements, over the 2011 dry season period, of aerosol optical depth, Angstrom exponent number and its fine mode counterpart obtained from photometric measurements at AERONET's newest site located at the city of Kuching, Sarawak, East Malaysia. This site was set up as part of the collaborative efforts of the Seven South East Asian Studies (7SEAS) regional aerosol measurements initiative. Located at the converging zone between peninsular Malaysia and the land masses of Sumatra, Borneo, Java and Sulawesi, this site is expected to provide first hand evidence about the physical and optical characteristics of the regional aerosol environment, specially during the biomass burning months. Moreover, given its relative proximity to our Singapore radiation measurement super-site, Kuching is expected to provide further insight on aerosol transport pathways caused by seasonal winds transporting smoke to other parts of the maritime continent and the South Asia region.

  3. LBA-ECO TG-03 Aeronet Aerosol Optical Thickness Measurements, Brazil: 1993-2005

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes aerosol optical thickness measurements from the CIMEL sunphotometer for 22 sites in Brazil during the period from 1993-2005. The AERONET...

  4. LBA-ECO TG-03 Aeronet Aerosol Optical Thickness Measurements, Brazil: 1993-2005

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set includes aerosol optical thickness measurements from the CIMEL sunphotometer for 22 sites in Brazil during the period from 1993-2005. The...

  5. Pulmonary deposition of urban atmospheric aerosol. Assessments of the mass, number and surface of the deposited particles; Deposizione polmonare dell'aerosol atmosferico urbano in termini di massa, numero e superficie delle particelle

    Energy Technology Data Exchange (ETDEWEB)

    Luciani, A.; Berico, M.; Castellani, C.M. [ENEA, Centro Ricerche Ezio Clementel, Bologna (Italy). Dipt. Ambiente

    1998-07-01

    Pulmonary deposition of urban atmospheric aerosol has been calculated by means of the data derived from March 1995 measurement campaign of urban aerosol. The human respiratory tract model of the International Commission on Radiological Protection (n. 66) developed for radiation protection purposes has been used. The number and surface of the deposited particles, as well as the mass, have been also evaluated. [Italian] I dati relativi alla campagna di misure effettuata nel marzo 1995 sono stati rielaborati al fine di valutare la deposizione polmonare dell'aerosol atmosferico in area urbana. Le valutazioni di deposizione nel tratto respiratorio umano sono state condotte mediante l'utilizzo del modello del tratto respiratorio umano presentato per fini radioprotezionistici dalla International Commission on Radiological Protection (n. 66). Sono state effettuate valutazioni di deposizione in massa e in termini di numero e superficie delle particelle.

  6. Aerosol optical properties in the mega-cities Beijing and Guangzhou: Measurements and implications for regional air pollution, aerosol sources and remote sensing

    Science.gov (United States)

    Garland, R. M.; Yang, H.; Schmid, O.; Rose, D.; Gunthe, S. S.

    2009-04-01

    wavelength dependence (curvature) that was related to the ratio of fine and coarse particle mass (PM1/PM10) as well as the surface mode diameter of the fine particle fraction. The results demonstrate consistency between in situ measurements and a remote sensing formalism with regard to the fine particle fraction and volume mode diameter, but there are also systematic deviations for the larger mode diameters. Thus we suggest that more data sets from in situ measurements of aerosol optical parameters and particle size distributions should be used to evaluate formalisms applied in aerosol remote sensing. Moreover, we observed a negative correlation between single scattering albedo and backscatter fraction, and we found that it affects the impact that these parameters have on aerosol radiative forcing efficiency and should be considered in model studies of Beijing, Guangzhou and similarly polluted mega-city regions. References: Garland, R. M., Yang, H., Schmid, O., Rose, D., Nowak, A., Achtert, P., Wiedensohler, A., Takegawa, N., Kita, K., Miyazaki, Y., Kondo, Y., Hu, M., Shao, M., Zeng, L. M., Zhang, Y. H., Andreae, M. O., and Pöschl, U.: Aerosol optical properties in a rural environment near the mega-city Guangzhou, China: implications for regional air pollution, radiative forcing and remote sensing, Atmospheric Chemistry and Physics, 8, 5161-5186, 2008. Garland, R. M., Schmid, O., Rose, D., Nowak, A., Achtert, P., Wiedensohler, A., Gunthe, S.S., Takegawa, N., Kita, K., Kondo, Y., Hu, M., Shao, M., Zeng, L. M., Zhu, T., Andreae, M. O., and Pöschl, U.: Aerosol optical properties observed during CAREBeijing-2006: Characteristic differences between the inflow and outflow of Beijing city air, Journal of Geophysical Research - Atmospheres, in press, 2009.

  7. Fast Airborne Aerosol Size and Chemistry Measurements with the High Resolution Aerosol Mass Spectrometer during the MILAGRO Campaign

    Science.gov (United States)

    DeCarlo, P. F.; Dunlea, E. J.; Kimmel, J. R.; Aiken, A. C.; Sueper, D.; Crounse, J.; Wennberg, P. O.; Emmons, L.; Shinozuka, Y.; Clarke, A.; hide

    2007-01-01

    The concentration, size, and composition of non-refractory submicron aerosol (NR-PM(sub l)) was measured over Mexico City and central Mexico with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) onboard the NSF/NCAR C-130 aircraft as part of the MILAGRO field campaign. This was the first aircraft deployment of the HR-ToF-AMS. During the campaign the instrument performed very well, and provided 12 s data. The aerosol mass from the AMS correlates strongly with other aerosol measurements on board the aircraft. Organic aerosol (OA) species dominate the NR-PM(sub l) mass. OA correlates strongly with CO and HCN indicating that pollution (mostly secondary OA, SOA) and biomass burning (BB) are the main OA sources. The OA to CO ratio indicates a typical value for aged air of around 80 microg/cubic m (STP) ppm(exp -1). This is within the range observed in outflow from the Northeastern US, which could be due to a compensating effect between higher BB but lower biogenic VOC emissions during this study. The O/C atomic ratio for OA is calculated from the HR mass spectra and shows a clear increase with photochemical age, as SOA forms rapidly and quickly overwhelms primary urban OA, consistent with Volkamer et al. (2006) and Kleinman et al. (2008). The stability of the OA/CO while O/C increases with photochemical age implies a net loss of carbon from the OA. BB OA is marked by signals at m/z 60 and 73, and also by a signal enhancement at large m/z indicative of larger molecules or more resistance to fragmentation. The main inorganic components show different spatial patterns and size distributions. Sulfate is regional in nature with clear volcanic and petrochemical/power plant sources, while the urban area is not a major regional source for this species. Nitrate is enhanced significantly in the urban area and immediate outflow, and is strongly correlated with CO indicating a strong urban source. The importance of nitrate decreases with distance from the city

  8. Direct Measurement of Interparticle Forces of Titan Aerosol Analogs ("Tholin") Using Atomic Force Microscopy

    Science.gov (United States)

    Yu, Xinting; Hörst, Sarah M.; He, Chao; McGuiggan, Patricia; Bridges, Nathan T.

    2017-12-01

    To understand the origin of the dunes on Titan, it is important to investigate the material properties of Titan's organic sand particles on Titan. The organic sand may behave distinctively compared to the quartz/basaltic sand on terrestrial planets (Earth, Venus, and Mars) due to differences in interparticle forces. We measured the surface energy (through contact angle measurements) and elastic modulus (through Atomic Force Microscopy) of the Titan aerosol analog (tholin). We find that the surface energy of a tholin thin film is about 70.9 mN/m, and its elastic modulus is about 3.0 GPa (similar to hard polymers like PMMA and polystyrene). For two 20 μm diameter particles, the theoretical cohesion force is therefore 3.3 μN. We directly measured interparticle forces for relevant materials: tholin particles are 0.8 ± 0.6 μN, while the interparticle cohesion between walnut shell particles (a typical model materials for the Titan Wind Tunnel, TWT) is only 0.4 ± 0.1 μN. The interparticle cohesion forces are much larger for tholins and presumably Titan sand particles than materials used in the TWT. This suggests that we should increase the interparticle force in both analog experiments (TWT) and threshold models to correctly translate the results to real Titan conditions. The strong cohesion of tholins may also inform us how the small aerosol particles (˜1 μm) in Titan's atmosphere are transformed into large sand particles (˜200 μm). It may also support the cohesive sand formation mechanism suggested by Rubin and Hesp (2009), where only unidirectional wind is needed to form linear dunes on Titan.

  9. Joint Retrieval Of Surface Reflectance And Aerosol Properties: Application To MSG/SEVIRI in the framework of the aerosol_cci project

    Science.gov (United States)

    Luffarelli, Marta; Govaerts, Yves; Goossens, Cedric

    2017-04-01

    A new versatile algorithm for the joint retrieval of surface reflectance and aerosol properties has been developed and tested at Rayference. This algorithm, named Combined Inversion of Surface and Aerosols (CISAR), includes a fast physically-based Radiative Transfer Model (RTM) accounting for the surface reflectance anisotropy and its coupling with aerosol scattering. This RTM explicitly solves the radiative transfer equation during the inversion process, without relying on pre-calculated integrals stored in LUT, allowing for a continuous variation of the state variables in the solution space. The inversion is based on a Optimal Estimation (OE) approach, which seeks for the best balance between the information coming from the observation and the a priori information. The a priori information is any additional knowledge on the observed system and it can concern the magnitude of the state variable or constraints on temporal and spectral variability. Both observations and priori information are provided with the corresponding uncertainty. For each processed spectral band, CISAR delivers the surface Bidirectional Reflectance Factor (BRF) and aerosol optical thickness, discriminating the effects of small and large particles. It also provides the associated uncertainty covariance matrix for every processed pixels. In the framework of the ESA aerosol_cci project, CISAR is applied on TOA BRF acquired by SEVIRI onboard Meteosat Second Generation (MSG) in the VIS0.6, VIS0.8 and NIR1.6 spectral bands. SEVIRI observations are accumulated during several days to document the surface anisotropy and minimize the impact of clouds. While surface radiative properties are supposed constant during this accumulation period, aerosol properties are derived on an hourly basis. The information content of each MSG/SEVIRI band will be provided based on the analysis of the posterior uncertainty covariance matrix. The analysis will demonstrate in particular the capability of CISAR to decouple

  10. Single particle composition measurements of artificial Calcium Carbonate aerosols

    Science.gov (United States)

    Zorn, S. R.; Mentel, T. F.; Schwinger, T.; Croteau, P. L.; Jayne, J.; Worsnop, D. R.; Trimborn, A.

    2012-12-01

    Mineral dust, with an estimated total source from natural and anthropogenic emissions of up to 2800 Tg/yr, is one of the two largest contributors to total aerosol mass, with only Sea salt having a similar source strength (up to 2600 Tg/yr). The composition of dust particles varies strongly depending on the production process and, most importantly, the source location. Therefore, the composition of single dust particles can be used both to trace source regions of air masses as well as to identify chemical aging processes. Here we present results of laboratory studies on generating artificial calcium carbonate (CaCO3) particles, a model compound for carbonaceous mineral dust particles. Particles were generated by atomizing an aqueous hydrogen carbonate solution. Water was removed using a silica diffusion dryer., then the particles were processed in an oven at temperatures up to 900°C, converting the hydrogen carbonate to its anhydrous form. The resulting aerosol was analyzed using an on-line single particle laser ablation aerosol particle time-of-flight mass spectrometer (LAAPTOF). The results confirm the conversion to calcium carbonate, and validate that the produced particles indeed can be used as a model compound for carbonaceous dust aerosols.

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

    International Nuclear Information System (INIS)

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

    2010-01-01

    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.

  12. Characterizing the impact of urban emissions on regional aerosol particles; airborne measurements during the MEGAPOLI experiment

    Science.gov (United States)

    Freney, E. J.; Sellegri, K.; Canonaco, F.; Colomb, A.; Borbon, A.; Michoud, V.; Doussin, J.-F.; Crumeyrolle, S.; Amarouch, N.; Pichon, J.-M.; Prévôt, A. S. H.; Beekmann, M.; Schwarzenböeck, A.

    2013-09-01

    The MEGAPOLI experiment took place in July 2009. The aim of this campaign was to study the aging and reactions of aerosol and gas-phase emissions in the city of Paris. Three ground-based measurement sites and several mobile platforms including instrument equipped vehicles and the ATR-42 aircraft were involved. We present here the variations in particle- and gas-phase species over the city of Paris using a combination of high-time resolution measurements aboard the ATR-42 aircraft. Particle chemical composition was measured using a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS) giving detailed information of the non-refractory submicron aerosol species. The mass concentration of BC, measured by a particle absorption soot photometer (PSAP), was used as a marker to identify the urban pollution plume boundaries. Aerosol mass concentrations and composition were affected by air-mass history, with air masses that spent longest time over land having highest fractions of organic aerosol and higher total mass concentrations. The Paris plume is mainly composed of organic aerosol (OA), black carbon and nitrate aerosol, as well as high concentrations of anthropogenic gas-phase species such as toluene, benzene, and NOx. Using BC and CO as tracers for air-mass dilution, we observe the ratio of ΔOA / ΔBC and ΔOA / ΔCO increase with increasing photochemical age (-log(NOx / NOy). Plotting the equivalent ratios for the Positive Matrix Factorization (PMF) resolved species (LV-OOA, SV-OOA, and HOA) illustrate that the increase in OA is a result of secondary organic aerosol (SOA). Within Paris the changes in the ΔOA / ΔCO are similar to those observed during other studies in Mexico city, Mexico and in New England, USA. Using the measured VOCs species together with recent organic aerosol formation yields we predicted ~ 50% of the measured organics. These airborne measurements during the MEGAPOLI experiment show that urban emissions contribute to the formation of OA

  13. Effect of surface coating with magnesium stearate via mechanical dry powder coating approach on the aerosol performance of micronized drug powders from dry powder inhalers.

    Science.gov (United States)

    Zhou, Qi Tony; Qu, Li; Gengenbach, Thomas; Larson, Ian; Stewart, Peter J; Morton, David A V

    2013-03-01

    The objective of this study was to investigate the effect of particle surface coating with magnesium stearate on the aerosolization of dry powder inhaler formulations. Micronized salbutamol sulphate as a model drug was dry coated with magnesium stearate using a mechanofusion technique. The coating quality was characterized by X-ray photoelectron spectroscopy. Powder bulk and flow properties were assessed by bulk densities and shear cell measurements. The aerosol performance was studied by laser diffraction and supported by a twin-stage impinger. High degrees of coating coverage were achieved after mechanofusion, as measured by X-ray photoelectron spectroscopy. Concomitant significant increases occurred in powder bulk densities and in aerosol performance after coating. The apparent optimum performance corresponded with using 2% w/w magnesium stearate. In contrast, traditional blending resulted in no significant changes in either bulk or aerosolization behaviour compared to the untreated sample. It is believed that conventional low-shear blending provides insufficient energy levels to expose host micronized particle surfaces from agglomerates and to distribute guest coating material effectively for coating. A simple ultra-high-shear mechanical dry powder coating step was shown as highly effective in producing ultra-thin coatings on micronized powders and to substantially improve the powder aerosolization efficiency.

  14. Comparison of ambient aerosol extinction coefficients obtained from in-situ, MAX-DOAS and LIDAR measurements at Cabauw

    NARCIS (Netherlands)

    Zieger, P.; Weingartner, E.; Henzing, J.; Moerman, M.; Leeuw, G. de; Mikkilä, J.; Ehn, M.; Petäjä, T.; Clémer, K.; Roozendael, M. van; Yilmaz, S.; Frieß, U.; Irie, H.; Wagner, T.; Shaiganfar, R.; Beirle, S.; Apituley, A.; Wilson, K.; Baltensperger, U.

    2011-01-01

    In the field, aerosol in-situ measurements are often performed under dry conditions (relative humidity RH<30-40%). Since ambient aerosol particles experience hygroscopic growth at enhanced RH, their microphysical and optical properties especially the aerosol light scattering are also strongly

  15. Long-Term Measurements of Carbon Monoxide and Aerosols at the ZOTTO tall tower, Siberia

    Science.gov (United States)

    Andreae, M. O.; Birmili, W.; Chi, X.; Heimann, M.; Heintzenberg, J.; Mikhailov, E.; Panov, A.

    2012-04-01

    The Zotino Tall Tower Observatory (ZOTTO), operated by the Max Planck Institutes for Biogeochemistry and Chemistry and the Institute of Forest (Krasnoyarsk), is located at 89.35°E, 60.80°N, 114 m asl. at a very remote continental site in Siberia, Russia. It centers on a 300-m tower designed for scientific measurements of chemical (trace gases, aerosol) and physical (meteorological) properties. The instrumentation at the observatory includes a CO Monitor, a Particle Soot Absorption Photometer (PSAP) for determining the aerosol absorption coefficient, a nephelometer for the determination of the aerosol scattering coefficient, and a Differential Mobility Particle Sizer (DMPS) to measure the aerosol number size distribution. We present measurements made from October 2006 until March 2011, with some interruptions due to technical reasons. An annual cycle of the background CO mixing rations was observed with summer minima around 90 ppb and winter maxima of about 175 ppb. Amplitude and phase of the annual cycle were generally similar to that reported by NOAA-ESRL for latitude 61°N, but showed an earlier onset of the elevated winter values. Episodes of elevated CO and aerosol concentrations, typically lasting for several days, are superimposed on the background seasonal cycle. During winter, these pollution episodes are usually associated with air masses that have passed over the central Siberian region around Omsk and Novosibirsk - a heavily industrialized area. During spring and summer, elevated levels of CO and aerosols are often caused by agricultural fires in southern Siberia and Kazakhstan or by forest fires in boreal Siberia. The optical properties of the aerosol showed more pronounced seasonal variability than the aerosol mass and number concentrations. Wintertime aerosols were highly absorbing, with single scattering albedos (SSA) around 0.85, consistent with a dominant fossil fuel combustion source. In contrast, summertime aerosols had very low absorption

  16. Characterizing the impact of urban emissions on regional aerosol particles: airborne measurements during the MEGAPOLI experiment

    Science.gov (United States)

    Freney, E. J.; Sellegri, K.; Canonaco, F.; Colomb, A.; Borbon, A.; Michoud, V.; Doussin, J.-F.; Crumeyrolle, S.; Amarouche, N.; Pichon, J.-M.; Bourianne, T.; Gomes, L.; Prevot, A. S. H.; Beekmann, M.; Schwarzenböeck, A.

    2014-02-01

    The MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation) experiment took place in July 2009. The aim of this campaign was to study the aging and reactions of aerosol and gas-phase emissions in the city of Paris. Three ground-based measurement sites and several mobile platforms including instrument equipped vehicles and the ATR-42 aircraft were involved. We present here the variations in particle- and gas-phase species over the city of Paris, using a combination of high-time resolution measurements aboard the ATR-42 aircraft. Particle chemical composition was measured using a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS), giving detailed information on the non-refractory submicron aerosol species. The mass concentration of black carbon (BC), measured by a particle absorption soot photometer (PSAP), was used as a marker to identify the urban pollution plume boundaries. Aerosol mass concentrations and composition were affected by air-mass history, with air masses that spent longest time over land having highest fractions of organic aerosol and higher total mass concentrations. The Paris plume is mainly composed of organic aerosol (OA), BC, and nitrate aerosol, as well as high concentrations of anthropogenic gas-phase species such as toluene, benzene, and NOx. Using BC and CO as tracers for air-mass dilution, we observe the ratio of ΔOA / ΔBC and ΔOA / ΔCO increase with increasing photochemical age (-log(NOx / NOy)). Plotting the equivalent ratios of different organic aerosol species (LV-OOA, SV-OOA, and HOA) illustrate that the increase in OA is a result of secondary organic aerosol (SOA) formation. Within Paris the changes in the ΔOA / ΔCO are similar to those observed during other studies in London, Mexico City, and in New England, USA. Using the measured SOA volatile organic compounds (VOCs) species together with organic aerosol formation

  17. Aerosol direct effect retrieval over clouds from space-borne passive hyperspectral measurements (Invited)

    Science.gov (United States)

    de Graaf, M.; Tilstra, L.; Stammes, P.

    2013-12-01

    A novel approach for the retrieval of the aerosol direct radiative effect (DRE) over clouds will be presented, which is independent of aerosol parameters estimates. The direct effect at the top of the atmosphere (TOA) of aerosols over clouds can be estimated using hyperspectral reflectance measurements from space-borne spectrometers, when the equivalent aerosol-unpolluted cloud scene reflectance spectrum is known. For smoke over clouds the cloud parameters can be estimated from the shortwave infrared (SWIR), where the absorption of the small smoke particles becomes sufficiently small. Using precomputed tables of cloud reflectance spectra, the unpolluted cloud scene spectrum can then be simulated and compared to the real measured polluted cloud scene reflectance spectrum. The UV-radiation absorption by the smoke will lead to a difference between the measured and simulated spectra, which is proportional to the aerosol DRE at TOA. Aerosol microphysical assumptions and retrievals are avoided by modeling only the aerosol-free scene spectra, all the aerosol effects are in the reflectance measurements. The method works especially well for cloud scenes, which can be simulated relatively accurately. An algorithm was developed to derive the aerosol DRE over marine clouds, using the space-borne spectrometer SCIAMACHY, which produced shortwave reflectance spectra (from 240 to 1700 nm contiguously) from 2002 till 2012. These are ideally suited to study the effect of aerosols on the shortwave spectrum. However, since aerosols in general do not have high resolution spectral features, the algorithm can be adapted to suit data from any combination of instruments that measures UV, visible and SWIR reflectances simultaneously. Examples include OMI and MODIS, flying in the A-Train constellation, and TROPOMI, on the future Sentinel 5 precursor mission, combined with NOAA's NPP VIIRS. This would produce aerosol DRE estimates with unprecedented accuracy and spatial resolution. The

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

    Directory of Open Access Journals (Sweden)

    S. Lolli

    2018-03-01

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

  19. Rapid Measurements of Aerosol Size Distribution and Hygroscopic Growth via Image Processing with a Fast Integrated Mobility Spectrometer (FIMS)

    Science.gov (United States)

    Wang, Y.; Pinterich, T.; Spielman, S. R.; Hering, S. V.; Wang, J.

    2017-12-01

    Aerosol size distribution and hygroscopicity are among key parameters in determining the impact of atmospheric aerosols on global radiation and climate change. In situ submicron aerosol size distribution measurements commonly involve a scanning mobility particle sizer (SMPS). The SMPS scanning time is in the scale of minutes, which is often too slow to capture the variation of aerosol size distribution, such as for aerosols formed via nucleation processes or measurements onboard research aircraft. To solve this problem, a Fast Integrated Mobility Spectrometer (FIMS) based on image processing was developed for rapid measurements of aerosol size distributions from 10 to 500 nm. The FIMS consists of a parallel plate classifier, a condenser, and a CCD detector array. Inside the classifier an electric field separates charged aerosols based on electrical mobilities. Upon exiting the classifier, the aerosols pass through a three stage growth channel (Pinterich et al. 2017; Spielman et al. 2017), where aerosols as small as 7 nm are enlarged to above 1 μm through water or heptanol condensation. Finally, the grown aerosols are illuminated by a laser sheet and imaged onto a CCD array. The images provide both aerosol concentration and position, which directly relate to the aerosol size distribution. By this simultaneous measurement of aerosols with different sizes, the FIMS provides aerosol size spectra nearly 100 times faster than the SMPS. Recent deployment onboard research aircraft demonstrated that the FIMS is capable of measuring aerosol size distributions in 1s (Figure), thereby offering a great advantage in applications requiring high time resolution (Wang et al. 2016). In addition, the coupling of the FIMS with other conventional aerosol instruments provides orders of magnitude more rapid characterization of aerosol optical and microphysical properties. For example, the combination of a differential mobility analyzer, a relative humidity control unit, and a FIMS was

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

    Science.gov (United States)

    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; hide

    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.

  1. Measurements of optical properties for tropospheric aerosols in the Artic; Messung von optischen Eigenschaften troposphaerischer Aerosole in der Arktis

    Energy Technology Data Exchange (ETDEWEB)

    Schumacher, R.

    2001-07-01

    Two different methods for the derivation of the altitude resolved aerosol extinction profiles are applied. The Klett method, which needs only the elastical backscattered lidar signal, allows the determination of the extinction coefficient indirectly at day and nighttime. For the Klett method an assumption of the extinction-to-backscatter ratio, often called 'lidar ratio', is necessary. This can be determined iteratively by combining with the airborne photometer measurements. With this method small scale inhomogenities and the high variability of fine structured aerosol layers can be recorded. In contract to this the Raman method allows to calculate the extinction coefficient without an assumption of the lidar ratio. Here only the Raman backscattered light from nitrogen is used. The procedure is limited in temporal and spatial resolution because the Raman backscatter cross section is smaller than the elastic backscatter cross section by three orders of magnitude. A sensitivity study shows the feasibility of this method. (orig.) [German] In dieser Arbeit werden zwei unterschiedliche Methoden zur Ableitung hochaufgeloester Extinktionsprofile des troposphaerischen Aerosols angewendet. Die Klett-Methode, in die ausschliesslich die elastisch rueckgestreuten Lidarsignale eingehen, erlaubt es indirekt auch waehrend des Polartages hochaufgeloeste Extinktionsprofile abzuleiten. Hierzu ist die Annahme ueber das Extinktions-zu-Rueckstreuverhaeltnisses, welches haeufig auch als Lidarverhaeltnis bezeichnet wird, notwendig. Dieses wird durch Kombination mit den flugzeuggetragenen Photometermessungen iteriert. Mit dieser Methode koennen somit auch kleinskalige Inhomogenitaeten aufgeloest und die hohe zeitliche Variabilitaet der Aerosolschichten erfasst werden. Im Gegensatz hierzu bietet die Raman-Methode den Vorteil, die Aerosol-Extinktion direkt ohne Annahme des Lidarverhaeltnisses abzuleiten. Bei der Ableitung der Aerosolextinktion gehen ausschliesslich die an

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

    Science.gov (United States)

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

    2012-01-01

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

  3. SAGE aerosol measurements. Volume 1, February 21, 1979 to December 31, 1979

    International Nuclear Information System (INIS)

    Mccormick, M.P.

    1985-10-01

    The Stratospheric Aerosol and Gas Experiment (SAGE) satellite system, launched on February 18, 1979, provides profiles of aerosol extinction, ozone concentration, and nitrogen dioxide concentration between about 80 N and 80 S. Zonal averages, separated into sunrise and sunset events, and seasonal averages of the aerosol extinction at 1.00 microns and 0.45 microns ratios of the aerosol extinction to the molecular extinction at 1.00 microns, and ratios of the aerosol extinction at 0.45 microns to the aerosol extinction at 1.00 microns are given. The averages for 1979 are shown in tables and in profile and contour plots (as a function of altitude and latitude). In addition, temperature data provided by the National Oceanic and Atmospheric Administration (NOAA) for the time and location of each SAGE measurement are averaged and shown in a similar format. Typical values of the peak aerosol extinction were 0.0001 to 0.0002 km at 1.00 microns depth values for the 1.00 microns channel varied between 0.001 and 0.002 over all latitudes

  4. Effect of Spectrally Varying Albedo of Vegetation Surfaces on Shortwave Radiation Fluxes and Aerosol Direct Radiative Forcing

    Science.gov (United States)

    Zhu, L.; Martins, J. V.; Yu, H.

    2012-01-01

    This study develops an algorithm for representing detailed spectral features of vegetation albedo based on Moderate Resolution Imaging Spectrometer (MODIS) observations at 7 discrete channels, referred to as the MODIS Enhanced Vegetation Albedo (MEVA) algorithm. The MEVA algorithm empirically fills spectral gaps around the vegetation red edge near 0.7 micrometers and vegetation water absorption features at 1.48 and 1.92 micrometers which cannot be adequately captured by the MODIS 7 channels. We then assess the effects of applying MEVA in comparison to four other traditional approaches to calculate solar fluxes and aerosol direct radiative forcing (DRF) at the top of atmosphere (TOA) based on the MODIS discrete reflectance bands. By comparing the DRF results obtained through the MEVA method with the results obtained through the other four traditional approaches, we show that filling the spectral gap of the MODIS measurements around 0.7 micrometers based on the general spectral behavior of healthy green vegetation leads to significant improvement in the instantaneous aerosol DRF at TOA (up to 3.02Wm(exp -2) difference or 48% fraction of the aerosol DRF, .6.28Wm(exp -2), calculated for high spectral resolution surface reflectance from 0.3 to 2.5 micrometers for deciduous vegetation surface). The corrections of the spectral gaps in the vegetation spectrum in the near infrared, again missed by the MODIS reflectances, also contributes to improving TOA DRF calculations but to a much lower extent (less than 0.27Wm(exp -2), or about 4% of the instantaneous DRF). Compared to traditional approaches, MEVA also improves the accuracy of the outgoing solar flux between 0.3 to 2.5 micrometers at TOA by over 60Wm(exp -2) (for aspen 3 surface) and aerosol DRF by over 10Wm(exp -2) (for dry grass). Specifically, for Amazon vegetation types, MEVA can improve the accuracy of daily averaged aerosol radiative forcing in the spectral range of 0.3 to 2.5 micrometers at equator at the

  5. Aerosol optical properties and direct radiative forcing based on measurements from the China Aerosol Remote Sensing Network (CARSNET in eastern China

    Directory of Open Access Journals (Sweden)

    H. Che

    2018-01-01

    Full Text Available Aerosol pollution in eastern China is an unfortunate consequence of the region's rapid economic and industrial growth. Here, sun photometer measurements from seven sites in the Yangtze River Delta (YRD from 2011 to 2015 were used to characterize the climatology of aerosol microphysical and optical properties, calculate direct aerosol radiative forcing (DARF and classify the aerosols based on size and absorption. Bimodal size distributions were found throughout the year, but larger volumes and effective radii of fine-mode particles occurred in June and September due to hygroscopic growth and/or cloud processing. Increases in the fine-mode particles in June and September caused AOD440 nm  >  1.00 at most sites, and annual mean AOD440 nm values of 0.71–0.76 were found at the urban sites and 0.68 at the rural site. Unlike northern China, the AOD440 nm was lower in July and August (∼ 0.40–0.60 than in January and February (0.71–0.89 due to particle dispersion associated with subtropical anticyclones in summer. Low volumes and large bandwidths of both fine-mode and coarse-mode aerosol size distributions occurred in July and August because of biomass burning. Single-scattering albedos at 440 nm (SSA440 nm from 0.91 to 0.94 indicated particles with relatively strong to moderate absorption. Strongly absorbing particles from biomass burning with a significant SSA wavelength dependence were found in July and August at most sites, while coarse particles in March to May were mineral dust. Absorbing aerosols were distributed more or less homogeneously throughout the region with absorption aerosol optical depths at 440 nm  ∼  0.04–0.06, but inter-site differences in the absorption Angström exponent indicate a degree of spatial heterogeneity in particle composition. The annual mean DARF was −93 ± 44 to −79 ± 39 W m−2 at the Earth's surface and ∼ −40 W m−2 at the top of the atmosphere (for

  6. A new approach to characterise pharmaceutical aerosols: measurement of aerosol from a single dose aqueous inhaler with an optical particle counter.

    Science.gov (United States)

    Kuhli, Maren; Weiss, Maximilian; Steckel, Hartwig

    2010-01-31

    An in-line sampling system with dilution units for aqueous droplet aerosols from single dose inhalers (Berodual Respimat, Boehringer Ingelheim Pharma GmbH & Co. KG, Germany) for an optical particle counter is described. The device has been designed to interface with a white light aerosol spectrometer (welas digital 2100, Palas GmbH, Germany) that allows the time-resolved measurement of highly concentrated aerosols. Performance of the sampling system with regard to the measured particle size distribution (PSD) is compared to Next Generation Impactor (NGI) and to laser diffraction measurements (Sympatec Inhaler and open bench). Optimal settings of the sampling system lead to PSDs that correspond well to those measured by the evaporation minimising NGI approach (15 L/min, cooled) and laser diffraction. The better accuracy of the new dilution unit in presence of an additional aerosol sampling filter in comparison to a previously described aerosol sampling system is shown for different settings of the sampling system. This allows a more precise quantification of the delivered drug amount which is also well correlated to the aerosol volume measured by the welas system. In addition, using time-resolved welas measurements provides insight into droplet size, evaporation and size changes of aerosol clouds delivered by liquid inhalers. Copyright 2009 Elsevier B.V. All rights reserved.

  7. Evaluation of operational forecast model of aerosol transportation using ceilometer network measurements

    Science.gov (United States)

    Chan, Ka Lok; Wiegner, Matthias; Flentje, Harald; Mattis, Ina; Wagner, Frank; Gasteiger, Josef; Geiß, Alexander

    2017-04-01

    Due to technical improvements of ceilometers in recent years, ceilometer measurements are not only limited to determine cloud base heights but also providing information on the vertical aerosol distribution. Therefore, several national weather services implemented ceilometer networks. These measurements are e.g. valuable for the evaluation of the chemical transport model simulations. In this study, we present comparisons of European Centre for Medium-Range Weather Forecast Integrated Forecast System (ECMWF-IFS) model simulation of aerosol backscatter coefficients with ceilometer network measurements operated by the German weather service (DWD) . Five different types of aerosol are available in the model simulations which include two natural aerosols, sea salt and dust. The other three aerosol types, i.e. sulfate, organic carbon and black carbon, have significant anthropogenic contributions. As the model output provides mass mixing ratios of the above mentioned types of aerosol and the ceilometers measure attenuated backscatter (β∗) provided that calibration took place, it is necessary to determine a common physical quantity for the comparison. We have chosen the aerosol backscatter coefficient (β) for this purpose. The β-profiles are calculated from the mass mixing ratios of the model output assuming the inherent aerosol microphysics properties. It shall be emphasized that in the model calculations, all particles are assumed to be spherical. We have examined the sensitivity of the intercomparison on the hygroscopic growth of particles and on the role of particle shape. Our results show that the hygroscopic growth of particle is crucial (up to a factor of 22) in converting the model output to backscatter coefficient profiles whereas the effect of non-sphericity of dust particles is comparably small (˜44%). Furthermore, the calibration of the ceilometer signals can be an issue. The agreements between modeled and retrieved β-profiles show different

  8. Development of a 10 Hz measurement system for atmospheric aerosol concentration

    International Nuclear Information System (INIS)

    Bouarouri, Assia

    2014-01-01

    The goal is to develop an aerosol charger based on a corona discharge for atmospheric concentration measurements (10 3 -10 5 cm -3 ) within a response time of 100 ms. Two ion sources, point-to-hole and wire-to-slit have been characterized. The increase of the ion flow in the post-discharge by EHD ion confinement in both the discharge gap and the hole has been shown. At first, using an experimental survey driven in two mixing configurations, concentric and face-to-face, we have confirmed the aerosol diffusion charging law which depends on aerosol diameter and N i .t product, with N i , the ions concentration and t, the charging time. Thus, the originality of this charger relies on the very high heterogeneity of unipolar ion densities (N i 0 ≥10 9 cm -3 ) required to compensate the charging time of 50 ms. In these conditions, we have shown that aerosol diameter and the charging dynamic (which depends also on the diameter) control the aerosol trajectory. The chargers have, next, been compared in different operating conditions, mainly in terms of the maximal charging and the minimal losses. In the chosen charger (point-to-hole ion source and concentric mixing), the relations charge/mobility and losses according to diameter have been characterized. We have also shown the linearity of the charged particles current with the aerosol concentration which allows the current-concentration data inversion. The preliminary measurement system composed by the charger, the separator and the particle current measurements, satisfies the objectives of the study in terms of the concentration detection limit (10 3 cm -3 ) and the response time (100 ms). We have thus shown the feasibility of an atmospheric aerosol concentration measurement system at 10 Hz using a corona discharge charger provided that the separation power is improved. Furthermore, knowing that aerosol losses are negligible and the lower limit of the partial charging, the developed charger is adaptable with other

  9. Observation operator for the assimilation of aerosol type resolving satellite measurements into a chemical transport model

    Directory of Open Access Journals (Sweden)

    M. Schroedter-Homscheidt

    2010-11-01

    Full Text Available Modelling of aerosol particles with chemical transport models is still based mainly on static emission databases while episodic emissions cannot be treated sufficiently. To overcome this situation, a coupling of chemical mass concentration modelling with satellite-based measurements relying on physical and optical principles has been developed. This study deals with the observation operator for a component-wise assimilation of satellite measurements. It treats aerosol particles classified into water soluble, water insoluble, soot, sea salt and mineral dust containing aerosol particles in the atmospheric boundary layer as separately assimilated aerosol components. It builds on a mapping of aerosol classes used both in observation and model space taking their optical and chemical properties into account. Refractive indices for primary organic carbon particles, anthropogenic particles, and secondary organic species have been defined based on a literature review. Together with a treatment of different size distributions in observations and model state, this allows transforming the background from mass concentrations into aerosol optical depths. A two-dimensional, variational assimilation is applied for component-wise aerosol optical depths. Error covariance matrices are defined based on a validation against AERONET sun photometer measurements. Analysis fields are assessed threefold: (1 through validation against AERONET especially in Saharan dust outbreak situations, (2 through comparison with the British Black Smoke and Sulphur Dioxide Network for soot-containing particles, and (3 through comparison with measurements of the water soluble components SO4, NH4, and NO3 conducted by the EMEP (European Monitoring and Evaluation Programme network. Separately, for the water soluble, the soot and the mineral dust aerosol components a bias reduction and subsequent a root mean square error reduction is observed in the

  10. Validation of high-resolution aerosol optical thickness simulated by a global non-hydrostatic model against remote sensing measurements

    Science.gov (United States)

    Goto, Daisuke; Sato, Yousuke; Yashiro, Hisashi; Suzuki, Kentaroh; Nakajima, Teruyuki

    2017-02-01

    A high-performance computing resource allows us to conduct numerical simulations with a horizontal grid spacing that is sufficiently high to resolve cloud systems. The cutting-edge computational capability, which was provided by the K computer at RIKEN in Japan, enabled the authors to perform long-term, global simulations of air pollutions and clouds with unprecedentedly high horizontal resolutions. In this study, a next generation model capable of simulating global air pollutions with O(10 km) grid spacing by coupling an atmospheric chemistry model to the Non-hydrostatic Icosahedral Atmospheric Model (NICAM) was performed. Using the newly developed model, month-long simulations for July were conducted with 14 km grid spacing on the K computer. Regarding the global distributions of aerosol optical thickness (AOT), it was found that the correlation coefficient (CC) between the simulation and AERONET measurements was approximately 0.7, and the normalized mean bias was -10%. The simulated AOT was also compared with satellite-retrieved values; the CC was approximately 0.6. The radiative effects due to each chemical species (dust, sea salt, organics, and sulfate) were also calculated and compared with multiple measurements. As a result, the simulated fluxes of upward shortwave radiation at the top of atmosphere and the surface compared well with the observed values, whereas those of downward shortwave radiation at the surface were underestimated, even if all aerosol components were considered. However, the aerosol radiative effects on the downward shortwave flux at the surface were found to be as high as 10 W/m2 in a global scale; thus, simulated aerosol distributions can strongly affect the simulated air temperature and dynamic circulation.

  11. Wintertime measurements of aerosol acidity and trace elements in Wuhan, a city in central China

    Science.gov (United States)

    Waldman, J. M.; Lioy, P. J.; Zelenka, M.; Jing, L.; Lin, Y. N.; He, Q. C.; Qian, Z. M.; Chapman, R.; Wilson, W. E.

    A 2-week intensive ambient aerosol study was conducted in December 1988 in Wuhan (Hubei Province), a city of nearly 2 million located on the Yangtze River in central China (P.R.C.). This is an industrial region where soft coal burning is widespread, and emission controls for vehicles and industrial facilities are minimal. The sampling site was located in one of the civic centers where residential and commercial density is highest. An Andersen dichotomous sampler was operated with Teflon membrane filters to collect fine ( dp deficit in accountable FP components (total mass compared to the total of ionic plus element masses) as well as the black appearance of collected materials indicate an abundance of carbonaceous aerosol, as high as 100 μ m -3. (total mass compared to the total of ionic plus element masses) as well as the black appearance of collected materials indicate an abundance of carbonaceous aerosol, as high as 100 μ m -3 Aerosol acidity was negligible during most monitoring periods, H +: 14 (range 0-50 neq m -3, equivalent to 0-2.5 μm m -3 as H 2SO 4). Sulfur dioxide, measured by the West-Gaeke method for part of the study, concentrations were low. Although not directly measured, the aerosol measurments suggested that gaseous HCl (from refuse incineration) and NH 3 (animal wastes) concentrations might have been high. Higher aerosol acidity might be expected if HCl sources were more prominent and not neutralized by local ammonia or other base components.

  12. Aerosol extinction-to-backscatter ratio derived from passive satellite measurements

    Directory of Open Access Journals (Sweden)

    F.-M. Bréon

    2013-09-01

    Full Text Available Spaceborne reflectance measurements from the POLDER instrument are used to study the specific directional signature close to the backscatter direction. The data analysis makes it possible to derive the extinction-to-backscatter ratio (EBR, which is related to the inverse of the scattering phase function for an angle of 180° and is needed for a quantitative interpretation of lidar observations (active measurements. In addition, the multidirectional measurements are used to quantify the scattering phase function variations close to backscatter, which also provide some indication of the aerosol particle size and shape. The spatial distributions of both parameters show consistent patterns that are consistent with the aerosol type distributions. Pollution aerosols have an EBR close to 70, desert dust values are on the order of 50 and EBR of marine aerosols is close to 25. The scattering phase function shows an increase with the scattering angle close to backscatter. The relative increase ∂lnP/∂γ is close to 0.01 for dust and pollution type aerosols and 0.06 for marine type aerosols. These values are consistent with those retrieved from Mie simulations.

  13. Meteorological and Land Surface Properties Impacting Sea Breeze Extent and Aerosol Distribution in a Dry Environment

    Science.gov (United States)

    Igel, Adele L.; van den Heever, Susan C.; Johnson, Jill S.

    2018-01-01

    The properties of sea breeze circulations are influenced by a variety of meteorological and geophysical factors that interact with one another. These circulations can redistribute aerosol particles and pollution and therefore can play an important role in local air quality, as well as impact remote sensing. In this study, we select 11 factors that have the potential to impact either the sea breeze circulation properties and/or the spatial distribution of aerosols. Simulations are run to identify which of the 11 factors have the largest influence on the sea breeze properties and aerosol concentrations and to subsequently understand the mean response of these variables to the selected factors. All simulations are designed to be representative of conditions in coastal sub tropical environments and are thus relatively dry, as such they do not support deep convection associated with the sea breeze front. For this dry sea breeze regime, we find that the background wind speed was the most influential factor for the sea breeze propagation, with the soil saturation fraction also being important. For the spatial aerosol distribution, the most important factors were the soil moisture, sea-air temperature difference, and the initial boundary layer height. The importance of these factors seems to be strongly tied to the development of the surface-based mixed layer both ahead of and behind the sea breeze front. This study highlights potential avenues for further research regarding sea breeze dynamics and the impact of sea breeze circulations on pollution dispersion and remote sensing algorithms.

  14. Mobile LiDAR Measurement for Aerosol Investigation in South-Central Hebei, China

    Science.gov (United States)

    qin, kai; Wu, Lixin; Zheng, Yunhui; Wong Man, Sing; Wang, Runfeng; Hu, Mingyu; Lang, Hongmei; Wang, Luyao; Bai, Yang; Rao, Lanlan

    2016-04-01

    With the rapid industrialization and urbanization in China during the last decades, the increasing anthropogenic pollutant emissions have significantly caused serious air pollution problems which are adversely influencing public health. Hebei is one of the most air polluted provinces in China. In January 2013, an extremely severe and persistent haze episode with record-breaking PM2.5 outbreak affecting hundreds of millions of people occurred over eastern and northern China. During that haze episode, 7 of the top 10 most polluted cities in China were located in the Hebei Province according to the report of China's Ministry of Environmental Protection. To investigate and the spatial difference and to characterize the vertical distribution of aerosol in different regions of south-central Hebei, mobile measurements were carried out using a mini micro pulse LiDAR system (model: MiniMPL) in March 2014. The mobile LiDAR kit consisting of a MiniMPL, a vibration reduction mount, a power inverter, a Windows surface tablet and a GPS receiver were mounted in a car watching though the sunroof opening. For comparison, a fixed measurement using a traditional micro pulse LiDAR system (model: MPL-4B) was conducted simultaneously in Shijiazhuang, the capital of Hebei Province. The equipped car was driven from downtown Shijiazhuang by way of suburban and rural area to downtown Cangzhou, Handan, and Baoding respectively at almost stable speed around 100Km per hour along different routes which counted in total more than 1000Km. The results can be summarized as: 1) the spatial distribution of total aerosol optical depth along the measurement routes in south-central Hebei was controlled by local terrain and population in general, with high values in downtown and suburban in the plain areas, and low values in rural areas along Taihang mountain to the west and Yan mountain to the north; 2) obviously high AODs were obtained at roads crossing points, inside densely populated area and nearby

  15. Analysis of Visible/SWIR surface reflectance ratios for aerosol retrievals from satellite in Mexico City urban area

    Directory of Open Access Journals (Sweden)

    A. D. de Almeida Castanho

    2007-10-01

    Full Text Available The surface reflectance ratio between the visible (VIS and shortwave infrared (SWIR radiation is an important quantity for the retrieval of the aerosol optical depth (τa from the MODIS sensor data. Based on empirically determined VIS/SWIR ratios, MODIS τa retrieval uses the surface reflectance in the SWIR band (2.1 µm, where the interaction between solar radiation and the aerosol layer is small, to predict the visible reflectances in the blue (0.47 µm and red (0.66 µm bands. Therefore, accurate knowledge of the VIS/SWIR ratio is essential for achieving accurate retrieval of aerosol optical depth from MODIS. We analyzed the surface reflectance over some distinct surface covers in and around the Mexico City metropolitan area (MCMA using MODIS radiances at 0.66 µm and 2.1 µm. The analysis was performed at 1.5 km×1.5 km spatial resolution. Also, ground-based AERONET sun-photometer data acquired in Mexico City from 2002 to 2005 were analyzed for aerosol depth and other aerosol optical properties. In addition, a network of hand-held sun-photometers deployed in Mexico City, as part of the MCMA-2006 Study during the MILAGRO Campaign, provided an unprecedented measurement of τa in 5 different sites well distributed in the city. We found that the average RED/SWIR ratio representative of the urbanized sites analyzed is 0.73±0.06 for scattering angles <140° and goes up to 0.77±0.06 for higher ones. The average ratio for non-urban sites was significantly lower (approximately 0.55. In fact, this ratio strongly depends on differences in urbanization levels (i.e. relative urban to vegetation proportions and types of surface materials. The aerosol optical depth retrieved from MODIS radiances at a spatial resolution of 1.5 km×1.5 km and averaged within 10×10 km boxes were compared with collocated 1-h τa averaged from sun-photometer measurements. The use of the new RED

  16. The Finokalia Aerosol Measurement Experiment – 2008 (FAME-08: an overview

    Directory of Open Access Journals (Sweden)

    M. Pikridas

    2010-07-01

    Full Text Available A month (4 May to 8 June 2008 of ambient aerosol, air ion and gas phase sampling (Finokalia Aerosol Measurement Experiment 2008, FAME-08 was conducted at Finokalia, on the island of Crete, Greece. The purpose of the study was to characterize the physical and chemical properties of aged aerosol and to investigate new particle formation. Measurements included aerosol and air ion size distributions, size-resolved chemical composition, organic aerosol thermal volatility, water uptake and particle optical properties (light scattering and absorption. Statistical analysis of the aerosol mass concentration variations revealed the absence of diurnal patterns suggesting the lack of strong local sources. Sulfates accounted for approximately half of the particulate matter less than 1 micrometer in diameter (PM1 and organics for 28%. The PM1 organic aerosol fraction was highly oxidized with 80% water soluble. The supermicrometer particles were dominated by crustal components (50%, sea salt (24% and nitrates (16%. The organic carbon to elemental carbon (OC/EC ratio correlated with ozone measurements but with a one-day lag. The average OC/EC ratio for the study period was equal to 5.4. For three days air masses from North Africa resulted in a 6-fold increase of particulate matter less than 10 micrometers in diameter (PM10 and a decrease of the OC/EC ratio by a factor of 2. Back trajectory analysis, based on FLEXPART footprint plots, identified five source regions (Athens, Greece, Africa, other continental and marine, each of which influenced the PM1 aerosol composition and properties. Marine air masses had the lowest PM1 concentrations and air masses from the Balkans, Turkey and Eastern Europe the highest.

  17. Effect of surface albedo, water vapour, and atmospheric aerosols on the cloud-free shortwave radiative budget in the Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Di Biagio, C. [ENEA, Laboratory for Earth Observations and Analyses, Rome (Italy); University of Siena, Department of Earth Science, Siena (Italy); Di Sarra, A. [ENEA, Laboratory for Earth Observations and Analyses, Rome (Italy); Eriksen, P. [Danish Climate Centre, DMI, Danish Meteorological Institute, Copenhagen (Denmark); Ascanius, S.E. [DMI, Danish Meteorological Institute, Qaanaaq (Greenland); Muscari, G. [INGV, Istituto Nazionale di Geofisica e Vulcanologia, Rome (Italy); Holben, B. [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

    2012-08-15

    This study is based on ground-based measurements of downward surface shortwave irradiance (SW), columnar water vapour (wv), and aerosol optical depth ({tau}) obtained at Thule Air Base (Greenland) in 2007-2010, together with MODIS observations of the surface shortwave albedo (A). Radiative transfer model calculations are used in combination with measurements to separate the radiative effect of A ({Delta}SW{sub A}), wv ({Delta}SW{sub wv}), and aerosols ({Delta}SW{sub {tau}}) in modulating SW in cloud-free conditions. The shortwave radiation at the surface is mainly affected by water vapour absorption, which produces a reduction of SW as low as -100 Wm{sup -2} (-18%). The seasonal change of A produces an increase of SW by up to +25 Wm{sup -2} (+4.5%). The annual mean radiative effect is estimated to be -(21-22) Wm{sup -2} for wv, and +(2-3) Wm{sup -2} for A. An increase by +0.065 cm in the annual mean wv, to which corresponds an absolute increase in {Delta}SW{sub wv} by 0.93 Wm{sup -2} (4.3%), has been observed to occur between 2007 and 2010. In the same period, the annual mean A has decreased by -0.027, with a corresponding decrease in {Delta}SW{sub A} by 0.41 Wm{sup -2} (-14.9%). Atmospheric aerosols produce a reduction of SW as low as -32 Wm{sup -2} (-6.7%). The instantaneous aerosol radiative forcing (RF{sub {tau}}) reaches values of -28 Wm{sup -2} and shows a strong dependency on surface albedo. The derived radiative forcing efficiency (FE{sub {tau}}) for solar zenith angles between 55 and 70 is estimated to be (-120.6 {+-} 4.3) for 0.1 < A < 0.2, and (-41.2 {+-} 1.6) Wm{sup -2} for 0.5 < A < 0.6. (orig.)

  18. Impact of Aerosol-PBL Interactions on the Long-term Trend of Surface Air Quality in China

    Science.gov (United States)

    Li, Z.; Dong, Z.

    2017-12-01

    Particulate pollutants, or aerosol in general, can interact strongly with meteorological variables with the strongest interactions taking place in the planetary boundary layer (PBL). The PBL hosting the bulk of aerosols in the lower atmosphere is affected by aerosol radiative effects. Both aerosol scattering and absorption reduce the amount of solar radiation reaching the ground and thus reduce the sensible and latent heat fluxes that drive the diurnal evolution of the PBL. Moreover, aerosols can increase atmospheric stability by inducing a temperature inversion as a result of both scattering and absorbing of solar radiation, which suppresses dispersion of pollutants and leads to further increases in aerosol concentration. Such positive feedback is especially strong during severe pollution events. Knowledge of the PBL is thus crucial for understanding the interactions between air pollution and meteorology. Based on a recent review article and a new study, I will review some major findings concerning the impact of aerosol-PBL interactions on ground-level air quality with a particular focus on its impact on the long-term trend of air quality changes in China. It is found that in regions of strong aerosol absorption, the feedback may play an even more significant role in dictating the long-term trend than the emissions themselves. In regions of strong aerosol absorption, aerosol loading in the lower PBL near surface has been increasing, while the upper and beyond the PBL, an opposite trend exists. For the entire atmospheric column, there is a much weaker trend, implying that the aerosol-PBL interaction could play a more important role than the total emission. As such, cutting the emission of black carbon (BC) or any other types of absorbing aerosol is a key in improving air quality.

  19. A Multi-Year Aerosol Characterization for the Greater Tehran Area Using Satellite, Surface, and Modeling Data

    Directory of Open Access Journals (Sweden)

    Ewan Crosbie

    2014-04-01

    Full Text Available This study reports a multi-year (2000–2009 aerosol characterization for metropolitan Tehran and surrounding areas using multiple datasets (Moderate Resolution Imaging Spectroradiometer (MODIS, Multi-angle Imaging Spectroradiometer (MISR, Total Ozone Mapping Spectrometer (TOMS, Goddard Ozone Chemistry Aerosol Radiation and Transport (GOCART, and surface and upper air data from local stations. Monthly trends in aerosol characteristics are examined in the context of the local meteorology, regional and local emission sources, and air mass back-trajectory data. Dust strongly affects the region during the late spring and summer months (May–August when aerosol optical depth (AOD is at its peak and precipitation accumulation is at a minimum. In addition, the peak AOD that occurs in July is further enhanced by a substantial number of seasonal wildfires in upwind regions. Conversely, AOD is at a minimum during winter; however, reduced mixing heights and a stagnant lower atmosphere trap local aerosol emissions near the surface and lead to significant reductions in visibility within Tehran. The unique meteorology and topographic setting makes wintertime visibility and surface aerosol concentrations particularly sensitive to local anthropogenic sources and is evident in the noteworthy improvement in visibility observed on weekends. Scavenging of aerosol due to precipitation is evident during the winter when a consistent increase in surface visibility and concurrent decrease in AOD is observed in the days after rain compared with the days immediately before rain.

  20. Stratospheric aerosol particle size distribution based on multi-color polarization measurements of the twilight sky

    Science.gov (United States)

    Ugolnikov, Oleg S.; Maslov, Igor A.

    2018-03-01

    Polarization measurements of the twilight background with Wide-Angle Polarization Camera (WAPC) are used to detect the depolarization effect caused by stratospheric aerosol near the altitude of 20 km. Based on a number of observations in central Russia in spring and summer 2016, we found the parameters of lognormal size distribution of aerosol particles. This confirmed the previously published results of the colorimetric method as applied to the same twilights. The mean particle radius (about 0.1 micrometers) and size distribution are also in agreement with the recent data of in situ and space-based remote sensing of stratospheric aerosol. Methods considered here provide two independent techniques of the stratospheric aerosol study based on the twilight sky analysis.

  1. Underground measurements of aerosol in radon and thoron progeny activity distributions

    International Nuclear Information System (INIS)

    Khan, A.; Bandi, F.; Phillips, C.R.; Duport, P.

    1990-01-01

    Aerosol and activity distributions of 218 Polonium, 214 Lead, 214 Bismuth, and 212 Lead were determined in two different underground mining environments by means of an optimized time-delay counting scheme and diffusion batteries. In one environment, diesel equipment was operating; and in the other, electrically powered equipment. The two environments differed significantly in total aerosol concentration. In the diesel environment, in particular, aerosol concentrations were unsteady, and fluctuated with vehicular traffic and mining activities. As measured by radon progeny disequilibrium, the age of the air ranged from about 25 to 60 minutes. Thoron working levels were of the same order as radon working levels. In this paper, comparisons are made between the aerosol and activity size distributions in both the diesel and electric mine

  2. Volatility measurement of atmospheric submicron aerosols in an urban atmosphere in southern China

    Science.gov (United States)

    Cao, Li-Ming; Huang, Xiao-Feng; Li, Yuan-Yuan; Hu, Min; He, Ling-Yan

    2018-02-01

    Aerosol pollution has been a very serious environmental problem in China for many years. The volatility of aerosols can affect the distribution of compounds in the gas and aerosol phases, the atmospheric fates of the corresponding components, and the measurement of the concentration of aerosols. Compared to the characterization of chemical composition, few studies have focused on the volatility of aerosols in China. In this study, a thermodenuder aerosol mass spectrometer (TD-AMS) system was deployed to study the volatility of non-refractory submicron particulate matter (PM1) species during winter in Shenzhen. To our knowledge, this paper is the first report of the volatilities of aerosol chemical components based on a TD-AMS system in China. The average PM1 mass concentration during the experiment was 42.7±20.1 µg m-3, with organic aerosol (OA) being the most abundant component (43.2 % of the total mass). The volatility of chemical species measured by the AMS varied, with nitrate showing the highest volatility, with a mass fraction remaining (MFR) of 0.57 at 50 °C. Organics showed semi-volatile characteristics (the MFR was 0.88 at 50 °C), and the volatility had a relatively linear correlation with the TD temperature (from the ambient temperature to 200 °C), with an evaporation rate of 0.45 % °C-1. Five subtypes of OA were resolved from total OA using positive matrix factorization (PMF) for data obtained under both ambient temperature and high temperatures through the TD, including a hydrocarbon-like OA (HOA, accounting for 13.5 %), a cooking OA (COA, 20.6 %), a biomass-burning OA (BBOA, 8.9 %), and two oxygenated OAs (OOAs): a less-oxidized OOA (LO-OOA, 39.1 %) and a more-oxidized OOA (MO-OOA, 17.9 %). Different OA factors presented different volatilities, and the volatility sequence of the OA factors at 50 °C was HOA (MFR of 0.56) > LO-OOA (0.70) > COA (0.85) ≈ BBOA (0.87) > MO-OOA (0.99), which was not completely consistent with the sequence of their O

  3. The Asian Tropopause Aerosol Layer: Balloon-Borne Measurements, Satellite Observations and Modeling Approaches

    Science.gov (United States)

    Fairlie, T. D.; Vernier, J.-P.; Natarajan, M.; Deshler, Terry; Liu, H.; Wegner, T.; Baker, N.; Gadhavi, H.; Jayaraman, A.; Pandit, A.; hide

    2016-01-01

    Satellite observations and numerical modeling studies have demonstrated that the Asian Summer Monsoon (ASM) can 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 associated with ASM anticyclone, in the upper troposphere and lower stratosphere (UTLS). 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 instrumentation, aircraft and satellite observations, combined 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-based observations from our BATAL-2015 field campaign to India and Saudi Arabia in summer 2015, including in situ backscatter measurements from COBALD instruments, and some of 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 contributions to the ATAL, which is supported by simulations using the GEOS-Chem CTM. Source elimination studies conducted with the GEOS-Chem indicate that 80-90% of ATAL aerosols originate from south Asian sources, in contrast with some earlier studies.

  4. Radiative Energetics of Mineral Dust Aerosols from Ground-Based Measurements

    Science.gov (United States)

    Tsay, Si-Chee; Hansell, Richard A.

    2011-01-01

    Airborne dust aerosols worldwide contribute a significant part to air quality problems and, to some extent, regional climatic issues (e.g., radiative forcing, hydrological cycle, and primary biological productivity in oceans). Evaluating the direct solar radiative effect of dust aerosols is relatively straightforward due in part to the relatively large SIN ratio in broadband irradiance measurements. The longwave (LW) impact, on the other hand, is rather difficult to ascertain since the measured dust signal level (approx.10 W/sq m) is on the same order as the instrumental uncertainties. Although the magnitude of the LW impact is much smaller than that of the shortwave (SW), it can still have a noticeable influence on the energy distribution of Earth-atmosphere system, particularly due to the strong light-absorptive properties commonly found in many terrestrial minerals. The current effort is part of an ongoing research study to perform a global assessment of dust direct aerosol radiative effects (DARE) during major field deployments of key dust source regions worldwide. In this work we present results stemming from two previous field deployments: the 2006 NASA African Monsoon Multidisciplinary Activities and the 2008 Asian Monsoon Years, both utilizing NASA Goddard's mobile ground-based facility. The former study focused on transported Saharan dust at Sal (16.73degN, 22.93degW), Cape Verde along the west coast of Africa while the latter focused on Asian dust at Zhangye (39.082degN, 100.276degE), China near the source between the Taklimakan and Gobi deserts. Due to the compelling variability in spatial and temporal scale of dust properties during field experiments, a deterministic I-D radiative transfer model constrained by local measurements (i.e., spectral photometry/interferometry and lidar for physical/microphysical, mineralogy, and single-scattering properties) is employed to evaluate dust's local instantaneous SW/LW DARE both at the surface and at the top of

  5. Modelling and measurements of urban aerosol processes on the neighborhood scale in Rotterdam, Oslo and Helsinki

    Science.gov (United States)

    Karl, M.; Kukkonen, J.; Keuken, M. P.; Lützenkirchen, S.; Pirjola, L.; Hussein, T.

    2015-12-01

    This study evaluates the influence of aerosol processes on the particle number (PN) concentrations in three major European cities on the temporal scale of one hour, i.e. on the neighborhood and city scales. We have used selected measured data of particle size distributions from previous campaigns in the cities of Helsinki, Oslo and Rotterdam. The aerosol transformation processes were evaluated using an aerosol dynamics model MAFOR, combined with a simplified treatment of roadside and urban atmospheric dispersion. We have compared the model predictions of particle number size distributions with the measured data, and conducted sensitivity analyses regarding the influence of various model input variables. We also present a simplified parameterization for aerosol processes, which is based on the more complex aerosol process computations; this simple model can easily be implemented to both Gaussian and Eulerian urban dispersion models. Aerosol processes considered in this study were (i) the coagulation of particles, (ii) the condensation and evaporation of n-alkanes, and (iii) dry deposition. The chemical transformation of gas-phase compounds was not taken into account. It was not necessary to model the nucleation of gas-phase vapors, as the computations were started with roadside conditions. Dry deposition and coagulation of particles were identified to be the most important aerosol dynamic processes that control the evolution and removal of particles. The effect of condensation and evaporation of organic vapors emitted by vehicles on particle numbers and on particle size distributions was examined. Under inefficient dispersion conditions, condensational growth contributed significantly to the evolution of PN from roadside to the neighborhood scale. The simplified parameterization of aerosol processes can predict particle number concentrations between roadside and the urban background with an inaccuracy of ∼ 10 %, compared to the fully size-resolved MAFOR model.

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

    Science.gov (United States)

    Kaloshin, G. A.

    2010-04-01

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

  7. Measurement of aerosol optical depth and sub-visual cloud detection using the optical depth sensor (ODS)

    Science.gov (United States)

    Toledo, D.; Rannou, P.; Pommereau, J.-P.; Sarkissian, A.; Foujols, T.

    2016-02-01

    A small and sophisticated optical depth sensor (ODS) has been designed to work in the atmosphere of Mars. The instrument measures alternatively the diffuse radiation from the sky and the attenuated direct radiation from the Sun on the surface. The principal goals of ODS are to retrieve the daily mean aerosol optical depth (AOD) and to detect very high and optically thin clouds, crucial parameters in understanding the Martian meteorology and climatology. The detection of clouds is undertaken at twilight, allowing the detection and characterization of clouds with opacities below 0.03 (sub-visual clouds). In addition, ODS is capable to retrieve the aerosol optical depth during nighttime from moonlight measurements. Recently, ODS has been selected at the METEO meteorological station on board the ExoMars 2018 Lander. In order to study the performance of ODS under Mars-like conditions as well as to evaluate the retrieval algorithms for terrestrial measurements, ODS was deployed in Ouagadougou (Africa) between November 2004 and October 2005, a Sahelian region characterized by its high dust aerosol load and the frequent occurrence of Saharan dust storms. The daily average AOD values retrieved by ODS were compared with those provided by a CIMEL sunphotometer of the AERONET (Aerosol Robotic NETwork) network localized at the same location. Results represent a good agreement between both ground-based instruments, with a correlation coefficient of 0.77 for the whole data set and 0.94 considering only the cloud-free days. From the whole data set, a total of 71 sub-visual cirrus (SVC) were detected at twilight with opacities as thin as 1.10-3 and with a maximum of occurrence at altitudes between 14 and 20 km. Although further optimizations and comparisons of ODS terrestrial measurements are required, results indicate the potential of these measurements to retrieve the AOD and detect sub-visual clouds.

  8. Optical Properties of Biomass Burning Aerosols: Comparison of Experimental Measurements and T-Matrix Calculations

    Directory of Open Access Journals (Sweden)

    Samin Poudel

    2017-11-01

    Full Text Available The refractive index (RI is an important parameter in describing the radiative impacts of aerosols. It is important to constrain the RI of aerosol components, since there is still significant uncertainty regarding the RI of biomass burning aerosols. Experimentally measured extinction cross-sections, scattering cross-sections, and single scattering albedos for white pine biomass burning (BB aerosols under two different burning and sampling conditions were modeled using T-matrix theory. The refractive indices were extracted from these calculations. Experimental measurements were conducted using a cavity ring-down spectrometer to measure the extinction, and a nephelometer to measure the scattering of size-selected aerosols. BB aerosols were obtained by burning white pine using (1 an open fire in a burn drum, where the aerosols were collected in distilled water using an impinger, and then re-aerosolized after several days, and (2 a tube furnace to directly introduce the BB aerosols into an indoor smog chamber, where BB aerosols were then sampled directly. In both cases, filter samples were also collected, and electron microscopy images were used to obtain the morphology and size information used in the T-matrix calculations. The effective radius of the particles collected on filter media from the open fire was approximately 245 nm, whereas it was approximately 76 nm for particles from the tube furnace burns. For samples collected in distilled water, the real part of the RI increased with increasing particle size, and the imaginary part decreased. The imaginary part of the RI was also significantly larger than the reported values for fresh BB aerosol samples. For the particles generated in the tube furnace, the real part of the RI decreased with particle size, and the imaginary part was much smaller and nearly constant. The RI is sensitive to particle size and sampling method, but there was no wavelength dependence over the range considered (500

  9. Long term analysis of the columnar and surface aerosol relationship at an urban European coastal site

    Science.gov (United States)

    Segura, S.; Estellés, V.; Utrillas, M. P.; Martínez-Lozano, J. A.

    2017-10-01

    Simultaneous PM2.5, PM10 and columnar (ground and satellite based) AOD measurements have been analyzed at Burjassot site in the metropolitan area of Valencia (Spain) during the period 2007-2016. The site is representative of a south European city in the Western Mediterranean coastal area, influenced by local urban pollution but also from frequent Saharan dust events. First, multiannual statistics were performed to characterize the main aerosol burden characteristics. The averages and standard deviations resulted 18 ± 9 μg m-3, 25 ± 19 μg m-3, 0.15 ± 0.11, 0.23 ± 0.17, 0.19 ± 0.15 and 1.2 ± 0.3 for PM2.5, PM10, AERONET AOD, MODIS Terra AOD, MODIS Aqua AOD, and AERONET Ångström exponent AE, respectively. The AOD is always referred to 550 nm. PM10 and AOD showed seasonal patterns with maxima in summer and minima in winter. However, PM2.5 and AE did not show such an evident seasonality. The relationship between surface and columnar measurements show a poor correlation (r down to 0.30) for daily values, although the correlation increases to r up to 0.90 for yearly averages. The relationship between PM and AOD becomes more consistent when the databases are binned in intervals of 0.05 AOD. Results for AERONET and MODIS AOD are very similar, although for daily averages is slightly worse for satellite than ground based measurements. In order to explain some seasonality effects found, the mixing layer height has been included in the analysis. Results show that the correlation is maximum when PM2.5 is used and the mixing layer height is greater than 1 000 m (r > 0.90).

  10. Chemical data assimilation of geostationary aerosol optical depth and PM surface observations on regional aerosol modeling over the Korean Peninsula during KORUS-AQ campaign

    Science.gov (United States)

    Jung, J.; Choi, Y.; Souri, A.; Jeon, W.

    2017-12-01

    Particle matter(PM) has played a significantly deleterious role in affecting human health and climate. Recently, continuous high concentrations of PM in Korea attracted public attention to this critical issue, and the Korea-United States Air Quality Study(KORUS-AQ) campaign in 2016 was conducted to investigate the causes. For this study, we adjusted the initial conditions in the chemical transport model(CTM) to improve its performance over Korean Peninsula during KORUS-AQ period, using the campaign data to evaluate our model performance. We used the Optimal Interpolation(OI) approach and used hourly surface air quality measurement data from the Air Quality Monitoring Station(AQMS) by NIER and the aerosol optical depth(AOD) measured by a GOCI sensor from the geostationary orbit onboard the Communication Ocean and Meteorological Satellite(COMS). The AOD at 550nm has a 6km spatial resolution and broad coverage over East Asia. After assimilating the surface air quality observation data, the model accuracy significantly improved compared to base model result (without assimilation). It reported very high correlation value (0.98) and considerably decreased mean bias. Especially, it well captured some high peaks which was underpredicted by the base model. To assimilate satellite data, we applied AOD scaling factors to quantify each specie's contribution to total PM concentration and find-mode fraction(FMF) to define vertical distribution. Finally, the improvement showed fairly good agreement.

  11. Fine aerosol bulk composition measured on WP-3D research aircraft in vicinity of the Northeastern United States – results from NEAQS

    Directory of Open Access Journals (Sweden)

    C. Warneke

    2007-06-01

    Full Text Available During the New England Air Quality Study (NEAQS in the summer of 2004, airborne measurements were made of the major inorganic ions and the water-soluble organic carbon (WSOC of the submicron (PM1.0 aerosol. These and ancillary data are used to describe the overall aerosol chemical characteristics encountered during the study. Fine particle mass was estimated from particle volume and a calculated density based on measured particle composition. Fine particle organic matter (OM was estimated from WSOC and a mass balance analysis. The aerosol over the northeastern United States (U.S. and Canada was predominantly sulfate and associated ammonium, and organic components, although in unique plumes additional ionic components were also periodically above detection limits. In power generation regions, and especially in the Ohio River Valley region, the aerosol tended to be predominantly sulfate (~60% μg μg−1 and apparently acidic, based on an excess of measured anions compared to cations. In all other regions where sulfate concentrations were lower and a smaller fraction of overall mass, the cations and anions were balanced suggesting a more neutral aerosol. In contrast, the WSOC and estimated OM were more spatially uniform and the fraction of OM relative to PM mass was largely influenced by sources of sulfate. The study median OM mass fraction was 40%. Throughout the study region, sulfate and organic aerosol mass were highest near the surface and decreased rapidly with increasing altitude. The relative fraction of organic mass to sulfate was similar throughout all altitudes within the boundary layer (altitude less than 2.5 km, but was significantly higher at altitude layers in the free troposphere (above 2.5 km. A number of distinct biomass burning plumes from fires in Alaska and the Yukon were periodically intercepted, mostly at altitudes between 3 and 4 km. These plumes were associated with highest aerosol concentrations of the study and were

  12. In situ measurements of angular-dependent light scattering by aerosols over the contiguous United States

    Science.gov (United States)

    Reed Espinosa, W.; Vanderlei Martins, J.; Remer, Lorraine A.; Puthukkudy, Anin; Orozco, Daniel; Dolgos, Gergely

    2018-03-01

    This work provides a synopsis of aerosol phase function (F11) and polarized phase function (F12) measurements made by the Polarized Imaging Nephelometer (PI-Neph) during the Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) and the Deep Convection Clouds and Chemistry (DC3) field campaigns. In order to more easily explore this extensive dataset, an aerosol classification scheme is developed that identifies the different aerosol types measured during the deployments. This scheme makes use of ancillary data that include trace gases, chemical composition, aerodynamic particle size and geographic location, all independent of PI-Neph measurements. The PI-Neph measurements are then grouped according to their ancillary data classifications and the resulting scattering patterns are examined in detail. These results represent the first published airborne measurements of F11 and -F12/F11 for many common aerosol types. We then explore whether PI-Neph light-scattering measurements alone are sufficient to reconstruct the results of this ancillary data classification algorithm. Principal component analysis (PCA) is used to reduce the dimensionality of the multi-angle PI-Neph scattering data and the individual measurements are examined as a function of ancillary data classification. Clear clustering is observed in the PCA score space, corresponding to the ancillary classification results, suggesting that, indeed, a strong link exists between the angular-scattering measurements and the aerosol type or composition. Two techniques are used to quantify the degree of clustering and it is found that in most cases the results of the ancillary data classification can be predicted from PI-Neph measurements alone with better than 85 % recall. This result both emphasizes the validity of the ancillary data classification as well as the PI-Neph's ability to distinguish common aerosol types without additional information.

  13. From BASE-ASIA toward 7-SEAS: A satellite-surface perspective of boreal spring biomass-burning aerosols and clouds in Southeast Asia

    Science.gov (United States)

    Tsay, Si-Chee; Hsu, N. Christina; Lau, William K.-M.; Li, Can; Gabriel, Philip M.; Ji, Qiang; Holben, Brent N.; Judd Welton, E.; Nguyen, Anh X.; Janjai, Serm; Lin, Neng-Huei; Reid, Jeffrey S.; Boonjawat, Jariya; Howell, Steven G.; Huebert, Barry J.; Fu, Joshua S.; Hansell, Richard A.; Sayer, Andrew M.; Gautam, Ritesh; Wang, Sheng-Hsiang; Goodloe, Colby S.; Miko, Laddawan R.; Shu, Peter K.; Loftus, Adrian M.; Huang, Jingfeng; Kim, Jin Young; Jeong, Myeong-Jae; Pantina, Peter

    2013-10-01

    In this paper, we present recent field studies conducted by NASA's SMART-COMMIT (and ACHIEVE, to be operated in 2013) mobile laboratories, jointly with distributed ground-based networks (e.g., AERONET, http://aeronet.gsfc.nasa.gov/ and MPLNET, http://mplnet.gsfc.nasa.gov/) and other contributing instruments over northern Southeast Asia. These three mobile laboratories, collectively called SMARTLabs (cf. http://smartlabs.gsfc.nasa.gov/, Surface-based Mobile Atmospheric Research &Testbed Laboratories) comprise a suite of surface remote sensing and in-situ instruments that are pivotal in providing high spectral and temporal measurements, complementing the collocated spatial observations from various Earth Observing System (EOS) satellites. A satellite-surface perspective and scientific findings, drawn from the BASE-ASIA (2006) field deployment as well as a series of ongoing 7-SEAS (2010-13) field activities over northern Southeast Asia are summarized, concerning (i) regional properties of aerosols from satellite and in-situ measurements, (ii) cloud properties from remote sensing and surface observations, (iii) vertical distribution of aerosols and clouds, and (iv) regional aerosol radiative effects and impact assessment. The aerosol burden over Southeast Asia in boreal spring, attributed to biomass burning, exhibits highly consistent spatial and temporal distribution patterns, with major variability arising from changes in the magnitude of the aerosol loading mediated by processes ranging from large-scale climate factors to diurnal meteorological events. Downwind from the source regions, the tightly coupled-aerosol-cloud system provides a unique, natural laboratory for further exploring the micro- and macro-scale relationships of the complex interactions. The climatic significance is presented through large-scale anti-correlations between aerosol and precipitation anomalies, showing spatial and seasonal variability, but their precise cause-and-effect relationships

  14. Aerosol measurements on a metal waste volume reduction study

    International Nuclear Information System (INIS)

    Sehmel, G.A.; Schwendiman, L.C.; Lloyd, F.A.; Hodgson, W.H.

    1975-09-01

    Particulates generated in an experiment in which stainless steel scrap was melted by the exothermic reaction between silicon and oxygen were sampled. The objective of the sampling was to characterize the particles in the off-gas stream and to determine the total weight of particles airborne. The objective was only partially achieved since the mass of airborne particles was so large that full-flow sampling was possible only for a short period. The particles were analyzed and found to contain Si, Al, Na, and Ba, with Si representing the greatest component. The aerosol was characterized by being typically condensed fume with primary particles of submicron sizes

  15. Size specific indoor aerosol deposition measurements and derived I/O concentrations ratios

    DEFF Research Database (Denmark)

    Fogh, C.L.; Byrne, M.A.; Roed, Jørn

    1997-01-01

    The process of aerosol deposition on indoor surfaces has implications for human exposure to particulate contaminants of both indoor and outdoor origin. In the radiological context, current accident models assume a uniform Dose Reduction Factor (DRF) of 0.5 for indoor residence during the outdoor...

  16. Development of an Aerosol Opacity Retrieval Algorithm for Use with Multi-Angle Land Surface Images

    Science.gov (United States)

    Diner, D.; Paradise, S.; Martonchik, J.

    1994-01-01

    In 1998, the Multi-angle Imaging SpectroRadiometer (MISR) will fly aboard the EOS-AM1 spacecraft. MISR will enable unique methods for retrieving the properties of atmospheric aerosols, by providing global imagery of the Earth at nine viewing angles in four visible and near-IR spectral bands. As part of the MISR algorithm development, theoretical methods of analyzing multi-angle, multi-spectral data are being tested using images acquired by the airborne Advanced Solid-State Array Spectroradiometer (ASAS). In this paper we derive a method to be used over land surfaces for retrieving the change in opacity between spectral bands, which can then be used in conjunction with an aerosol model to derive a bound on absolute opacity.

  17. Role of near ultraviolet wavelength measurements in the detection and retrieval of absorbing aerosols from space

    Science.gov (United States)

    Mukai, Sonoyo; Fujito, Toshiyuki; Nakata, Makiko; Sano, Itaru

    2017-10-01

    Aerosol remote sensing by ultraviolet (UV) wavelength is established by a Total Ozone Mapping Spectrometer (TOMS) mounted on the long-life satellite Nimbus-7 and continues to make observations using Ozone monitoring instrument (OMI) located on the Aura satellite. For example, TOMS demonstrated that UV radiation (0.331 and 0.360 μm) could easily detect absorbing particles such as mineral dust or smoke aerosols. TOMS-AI (absorbing aerosol index) has been used to identify the absorbing aerosols from space. For an upcoming mission, JAXA/GCOM-C will have the polarization sensor SGLI boarded in December 2017. The SGLI has multi (19)-channels including near UV (0.380 μm) and violet (0.412 μm) wavelengths. This work intends to examine the role of near UV data in the detection of absorbing aerosols similar to TOMS-AI played. In practice, the measurements by GLI mounted on the short Japanese mission JAXA/ADEOS-2, whose data archive period was just 8 months from April to October in 2003, are available for simulation of SGLI data because ADEOS-2/GLI installed near UV and violet channels. First of all, the ratio of data at 0.412 μm to that at 0.380 μm is examined as an indicator to detect absorbing aerosols on a global scale during ADEOS-2 era. It is noted that our research group has developed an efficient algorithm for aerosol retrieval in hazy episodes (dense concentrations of atmospheric aerosols). It can be said that at least this work is an attempt to grasp the biomass burning plumes from the satellite.

  18. A new oxidation flow reactor for measuring secondary aerosol formation of rapidly changing emission sources

    Science.gov (United States)

    Simonen, Pauli; Saukko, Erkka; Karjalainen, Panu; Timonen, Hilkka; Bloss, Matthew; Aakko-Saksa, Päivi; Rönkkö, Topi; Keskinen, Jorma; Dal Maso, Miikka

    2017-04-01

    Oxidation flow reactors (OFRs) or environmental chambers can be used to estimate secondary aerosol formation potential of different emission sources. Emissions from anthropogenic sources, such as vehicles, often vary on short timescales. For example, to identify the vehicle driving conditions that lead to high potential secondary aerosol emissions, rapid oxidation of exhaust is needed. However, the residence times in environmental chambers and in most oxidation flow reactors are too long to study these transient effects ( ˜ 100 s in flow reactors and several hours in environmental chambers). Here, we present a new oxidation flow reactor, TSAR (TUT Secondary Aerosol Reactor), which has a short residence time ( ˜ 40 s) and near-laminar flow conditions. These improvements are achieved by reducing the reactor radius and volume. This allows studying, for example, the effect of vehicle driving conditions on the secondary aerosol formation potential of the exhaust. We show that the flow pattern in TSAR is nearly laminar and particle losses are negligible. The secondary organic aerosol (SOA) produced in TSAR has a similar mass spectrum to the SOA produced in the state-of-the-art reactor, PAM (potential aerosol mass). Both reactors produce the same amount of mass, but TSAR has a higher time resolution. We also show that TSAR is capable of measuring the secondary aerosol formation potential of a vehicle during a transient driving cycle and that the fast response of TSAR reveals how different driving conditions affect the amount of formed secondary aerosol. Thus, TSAR can be used to study rapidly changing emission sources, especially the vehicular emissions during transient driving.

  19. Tropospheric Aerosols

    Science.gov (United States)

    Buseck, P. R.; Schwartz, S. E.

    2003-12-01

    m, PM10=1.1 μg m-3; estimated coefficient of light scattering by particulate matter, σep, at 570 nm=12 Mm-1). (b) High aerosol concentration (PM2.5=43.9 μg m-3; PM10=83.4 μg m-3; estimated σep at 570 nm=245 Mm-1) (reproduced by permission of National Park Service, 2002). Although comprising only a small fraction of the mass of Earth's atmosphere, aerosol particles are highly important constituents of the atmosphere. Special interest has focused on aerosols in the troposphere, the lowest part of the atmosphere, extending from the land or ocean surface typically to ˜8 km at high latitudes, ˜12 km in mid-latitudes, and ˜16 km at low latitudes. That interest arises in large part because of the importance of aerosol particles in geophysical processes, human health impairment through inhalation, environmental effects through deposition, visibility degradation, and influences on atmospheric radiation and climate.Anthropogenic aerosols are thought to exert a substantial influence on Earth's climate, and the need to quantify this influence has sparked much of the current interest in and research on tropospheric aerosols. The principal mechanisms by which aerosols influence the Earth radiation budget are scattering and absorbing solar radiation (the so-called "direct effects") and modifying clouds and precipitation, thereby affecting both radiation and hydrology (the so-called "indirect effects"). Light scattering by aerosols increases the brightness of the planet, producing a cooling influence. Light-absorbing aerosols such as black carbon exert a warming influence. Aerosols increase the reflectivity of clouds, another cooling influence. These radiative influences are quantified as forcings, where a forcing is a perturbation to the energy balance of the atmosphere-Earth system, expressed in units of watts per square meter, W m-2. A warming influence is denoted a positive forcing, and a cooling influence, negative. The radiative direct and indirect forcings by

  20. Retrieval of aerosol microphysical properties from AERONET photopolarimetric measurements: 1. Information content analysis

    Science.gov (United States)

    Xu, Xiaoguang; Wang, Jun

    2015-07-01

    This paper is the first part of a two-part study that aims to retrieve aerosol particle size distribution (PSD) and refractive index from the multispectral and multiangular polarimetric measurements taken by the new-generation Sun photometer as part of the Aerosol Robotic Network (AERONET). It provides theoretical analysis and guidance to the companion study in which we have developed an inversion algorithm for retrieving 22 aerosol microphysical parameters associated with a bimodal PSD function from real AERONET measurements. Our theoretical analysis starts with generating the synthetic measurements at four spectral bands (440, 675, 870, and 1020 nm) with a Unified Linearized Vector Radiative Transfer Model for various types of spherical aerosol particles. Subsequently, the quantitative information content for retrieving aerosol parameters is investigated in four observation scenarios, i.e., I1, I2, P1, and P2. Measurements in the scenario (I1) comprise the solar direct radiances and almucantar radiances that are used in the current AERONET operational inversion algorithm. The other three scenarios include different additional measurements: (I2) the solar principal plane radiances, (P1) the solar principal plane radiances and polarization, and (P2) the solar almucantar polarization. Results indicate that adding polarization measurements can increase the degree of freedom for signal by 2-5 in the scenario P1, while not as much of an increase is found in the scenarios I2 and P2. Correspondingly, smallest retrieval errors are found in the scenario P1: 2.3% (2.9%) for the fine-mode (coarse-mode) aerosol volume concentration, 1.3% (3.5%) for the effective radius, 7.2% (12%) for the effective variance, 0.005 (0.035) for the real-part refractive index, and 0.019 (0.068) for the single-scattering albedo. These errors represent a reduction from their counterparts in scenario I1 of 79% (57%), 76% (49%), 69% (52%), 66% (46%), and 49% (20%), respectively. We further

  1. Assessment of cloud supersaturation by aerosol particle and cloud condensation nuclei (CCN) measurements

    Science.gov (United States)

    Krüger, Mira L.; Mertes, Stephan; Klimach, Thomas; Cheng, Yafang; Su, Hang; Schneider, Johannes; Andreae, Meinrat O.; Pöschl, Ulrich; Rose, Diana

    2014-05-01

    Atmospheric aerosols consist of particles spanning a wide range of size and chemical composition from various natural and anthropogenic sources. They can act as cloud condensation nuclei (CCN) and affect climate by influencing the properties of clouds and precipitation. The water vapor supersaturation at which aerosol particles are activated as CCN depends on particle size, composition and mixing state. Techniques for the direct measurement of cloud supersaturation are not available. Thus, indirect methods have been developed to estimate the value of water vapor supersaturation in a cloud, which determines the fraction of particles that are activated and form cloud droplets. In this study we show how size-resolved measurements of aerosol particles and cloud condensation nuclei (CCN) can be used to characterize the supersaturation of water vapor in a cloud. The method was developed and applied for the investigation of a cloud event during the ACRIDICON-Zugspitze campaign (17 Sep to 4 Oct 2012) at the high-alpine research station Schneefernerhaus (German Alps, 2650 m asl). Number size distributions of total and interstitial aerosol particles were measured with a scanning mobility particle sizer (SMPS), and size-resolved CCN efficiency spectra were recorded with a CCN counter system operated at different supersaturation levels. During the evolution of a cloud, aerosol particles are exposed to different supersaturation levels. We outline and compare different estimates for the lower and upper bounds (Slow, Shigh) and the average value (Savg) of peak supersaturation encountered by the particles in the cloud. For the investigated cloud event, we derived Slow ≡ 0.19% - 0.25%, Shigh ≡ 0.90% - 1.64% and Savg ≡ 0.38% - 0.84%. Estimates of Slow, Shigh and Savg based on aerosol size distribution data require specific knowledge or assumptions of aerosol hygroscopicity, which are not required for the derivation of Slow and Savg from the size-resolved CCN efficiency spectra.

  2. Spectro-Microscopic Measurements of Carbonaceous Aerosol Aging in Central California

    Energy Technology Data Exchange (ETDEWEB)

    Moffet, Ryan C.; Rodel, Tobias; Kelly, Stephen T.; Yu, Xiao-Ying; Carroll, Gregory; Fast, Jerome D.; Zaveri, Rahul A.; Laskin, Alexander; Gilles, Mary K.

    2013-10-29

    Carbonaceous aerosols are responsible for large uncertainties in climate models, degraded visibility, and adverse health effects. The Carbonaceous Aerosols and Radiative Effects Study (CARES) was designed to study carbonaceous aerosols in the natural environment of Central Valley, California, and learn more about their atmospheric formation and aging. This paper presents results from spectro-microscopic measurements of carbonaceous particles collected during CARES at the time of pollution accumulation event (June 27-29, 2010), when in situ measurements indicated an increase in the organic carbon content of aerosols as the Sacramento urban plume aged. Computer controlled scanning electron microscopy coupled with an energy dispersive X-ray detector (CCSEM/EDX) and scanning transmission X-ray microscopy coupled with near edge X-ray absorption spectroscopy (STXM/NEXAFS) were used to probe the chemical composition and morphology of individual particles. It was found that the mass of organic carbon on individual particles increased through condensation of secondary organic aerosol. STXM/NEXAFS indicated that the number fraction of homogenous organic particles lacking inorganic inclusions (greater than ~50 nm diameter) increased with plume age as did the organic mass per particle. Comparison of the CARES spectro-microscopic data set with a similar dataset obtained in Mexico City during the MILAGRO campaign showed that individual particles in Mexico City contained twice as much carbon as those sampled during CARES. The number fraction of soot particles at the Mexico City urban site (30%) was larger than at the CARES urban site (10%) and the most aged samples from CARES contained less carbon-carbon double bonds. Differences between carbonaceous particles in Mexico City and California result from different sources, photochemical conditions, gas phase reactants, and secondary organic aerosol precursors. The detailed results provided by these spectro-microscopic measurements

  3. Are atmospheric aerosols able to modify the surface winds? A sensitivity study of the biomass burning aerosols impact on the spatially-distributed wind over Europe

    Science.gov (United States)

    Baró, Rocío; Lorente-Plazas, Raquel; Jerez, Sonia; Montávez, Juan Pedro; Jiménez-Guerrero, Pedro

    2015-04-01

    and the turbulence, developing a more stable planetary boundary layer with lower heights (around 80 m). This implies a wind speed reduction of 0.4 m s-1 (spatial correlation between planetary boundary layer and wind speed is around 0.4). On the other hand, the decrease of the temperature favours an increase of the surface pressure not only over Russia but also extends towards northern Europe. Opposite, the surface pressure decreases over central Europe where there is an increase of the wind speed up to 0.4 m s-1. The indirect effects of the aerosols also affect wind direction, especially in the North Sea (around 10 degrees). This work evidences the importance of taking into account the aerosol radiative effects in order to improve the representativeness of winds and could help to estimate the wind energy.

  4. Highly controlled, reproducible measurements of aerosol emissions from combustion of a common African biofuel source

    Science.gov (United States)

    Haslett, Sophie L.; Thomas, J. Chris; Morgan, William T.; Hadden, Rory; Liu, Dantong; Allan, James D.; Williams, Paul I.; Keita, Sekou; Liousse, Cathy; Coe, Hugh

    2018-01-01

    Particulate emissions from biomass burning can both alter the atmosphere's radiative balance and cause significant harm to human health. However, due to the large effect on emissions caused by even small alterations to the way in which a fuel burns, it is difficult to study particulate production of biomass combustion mechanistically and in a repeatable manner. In order to address this gap, in this study, small wood samples sourced from Côte D'Ivoire in West Africa were burned in a highly controlled laboratory environment. The shape and mass of samples, available airflow and surrounding thermal environment were carefully regulated. Organic aerosol and refractory black carbon emissions were measured in real time using an Aerosol Mass Spectrometer and a Single Particle Soot Photometer, respectively. This methodology produced remarkably repeatable results, allowing aerosol emissions to be mapped directly onto different phases of combustion. Emissions from pyrolysis were visible as a distinct phase before flaming was established. After flaming combustion was initiated, a black-carbon-dominant flame was observed during which very little organic aerosol was produced, followed by a period that was dominated by organic-carbon-producing smouldering combustion, despite the presence of residual flaming. During pyrolysis and smouldering, the two phases producing organic aerosol, distinct mass spectral signatures that correspond to previously reported variations in biofuel emissions measured in the atmosphere are found. Organic aerosol emission factors averaged over an entire combustion event were found to be representative of the time spent in the pyrolysis and smouldering phases, rather than reflecting a coupling between emissions and the mass loss of the sample. Further exploration of aerosol yields from similarly carefully controlled fires and a careful comparison with data from macroscopic fires and real-world emissions will help to deliver greater constraints on the

  5. In situ measurements of cloud microphysics and aerosol over coastal Antarctica during the MAC campaign

    Directory of Open Access Journals (Sweden)

    S. J. O'Shea

    2017-11-01

    Full Text Available During austral summer 2015, the Microphysics of Antarctic Clouds (MAC field campaign collected unique and detailed airborne and ground-based in situ measurements of cloud and aerosol properties over coastal Antarctica and the Weddell Sea. This paper presents the first results from the experiment and discusses the key processes important in this region, which is critical to predicting future climate change. The sampling was predominantly of stratus clouds, at temperatures between −20 and 0 °C. These clouds were dominated by supercooled liquid water droplets, which had a median concentration of 113 cm−3 and an interquartile range of 86 cm−3. Both cloud liquid water content and effective radius increased closer to cloud top. The cloud droplet effective radius increased from 4 ± 2 µm near cloud base to 8 ± 3 µm near cloud top. Cloud ice particle concentrations were highly variable with the ice tending to occur in small, isolated patches. Below approximately 1000 m, glaciated cloud regions were more common at higher temperatures; however, the clouds were still predominantly liquid throughout. When ice was present at temperatures higher than −10 °C, secondary ice production most likely through the Hallett–Mossop mechanism led to ice concentrations 1 to 3 orders of magnitude higher than the number predicted by commonly used primary ice nucleation parameterisations. The drivers of the ice crystal variability are investigated. No clear dependence on the droplet size distribution was found. The source of first ice in the clouds remains uncertain but may include contributions from biogenic particles, blowing snow or other surface ice production mechanisms. The concentration of large aerosols (diameters 0.5 to 1.6 µm decreased with altitude and were depleted in air masses that originated over the Antarctic continent compared to those more heavily influenced by the Southern Ocean and sea ice regions. The

  6. In situ measurements of cloud microphysics and aerosol over coastal Antarctica during the MAC campaign

    Science.gov (United States)

    O'Shea, Sebastian J.; Choularton, Thomas W.; Flynn, Michael; Bower, Keith N.; Gallagher, Martin; Crosier, Jonathan; Williams, Paul; Crawford, Ian; Fleming, Zoë L.; Listowski, Constantino; Kirchgaessner, Amélie; Ladkin, Russell S.; Lachlan-Cope, Thomas

    2017-11-01

    During austral summer 2015, the Microphysics of Antarctic Clouds (MAC) field campaign collected unique and detailed airborne and ground-based in situ measurements of cloud and aerosol properties over coastal Antarctica and the Weddell Sea. This paper presents the first results from the experiment and discusses the key processes important in this region, which is critical to predicting future climate change. The sampling was predominantly of stratus clouds, at temperatures between -20 and 0 °C. These clouds were dominated by supercooled liquid water droplets, which had a median concentration of 113 cm-3 and an interquartile range of 86 cm-3. Both cloud liquid water content and effective radius increased closer to cloud top. The cloud droplet effective radius increased from 4 ± 2 µm near cloud base to 8 ± 3 µm near cloud top. Cloud ice particle concentrations were highly variable with the ice tending to occur in small, isolated patches. Below approximately 1000 m, glaciated cloud regions were more common at higher temperatures; however, the clouds were still predominantly liquid throughout. When ice was present at temperatures higher than -10 °C, secondary ice production most likely through the Hallett-Mossop mechanism led to ice concentrations 1 to 3 orders of magnitude higher than the number predicted by commonly used primary ice nucleation parameterisations. The drivers of the ice crystal variability are investigated. No clear dependence on the droplet size distribution was found. The source of first ice in the clouds remains uncertain but may include contributions from biogenic particles, blowing snow or other surface ice production mechanisms. The concentration of large aerosols (diameters 0.5 to 1.6 µm) decreased with altitude and were depleted in air masses that originated over the Antarctic continent compared to those more heavily influenced by the Southern Ocean and sea ice regions. The dominant aerosol in the region was hygroscopic in nature, with

  7. Marine and biomass burning aerosols in the southern Indian Ocean: Retrieval of aerosol optical properties from shipborne lidar and Sun photometer measurements

    Science.gov (United States)

    Duflot, V.; Royer, P.; Chazette, P.; Baray, J.-L.; Courcoux, Y.; Delmas, R.

    2011-09-01

    We document aerosol extinction properties in the southern Indian Ocean. A unique data set of shipborne measurements has been collected with a dual Rayleigh-Mie lidar aboard the research vessel Marion Dufresne during two campaigns: one around Madagascar during the Southern Hemisphere late summer and one close to the Kerguelen Islands during the biomass burning (BB) season. During this latter, a layer containing a mix of BB and marine aerosols extending up to ˜3 km above mean sea level (amsl) has been observed from [31°S, 69°E] to [24°S, 59°E]. Both vertical structure and aerosol optical properties have been retrieved from the inversion of the lidar signals. Sun photometer-derived aerosol optical thickness (AOT) at 355 nm is used to constrain the lidar inversion. We obtain a mean integrated value of backscatter-to-extinction ratio (BER) (extinction-to-backscatter ratio, or so-called lidar ratio, LR) of 0.039 ± 0.009 sr-1 (26 ± 6 sr) and 0.021 ± 0.006 sr-1 (48 ± 12 sr) for the marine aerosols layer, and for the mixing between BB and marine aerosols with an uncertainty of 0.009 sr-1 (6 sr) and 0.004 sr-1 (9 sr), respectively. Lidar calibration is used to inverse data without any simultaneous Sun photometer measurements (as nighttime data), and the temporal evolution of the optical properties and vertical extension of the BB aerosol plume is documented. The presence of BB aerosols is in agreement with Lagrangian model GIRAFE v3 (reGIonal ReAl time Fire plumEs) simulations, which show the South American and Southern African BB origin of the encountered aerosol layer.

  8. Consistency of aerosols above clouds characterization from A-Train active and passive measurements

    Science.gov (United States)

    Deaconu, Lucia T.; Waquet, Fabien; Josset, Damien; Ferlay, Nicolas; Peers, Fanny; Thieuleux, François; Ducos, Fabrice; Pascal, Nicolas; Tanré, Didier; Pelon, Jacques; Goloub, Philippe

    2017-09-01

    This study presents a comparison between the retrieval of optical properties of aerosol above clouds (AAC) from different techniques developed for the A-Train sensors CALIOP/CALIPSO and POLDER/PARASOL. The main objective is to analyse the consistency between the results derived from the active and the passive measurements. We compare the aerosol optical thickness (AOT) above optically thick clouds (cloud optical thickness (COT) larger than 3) and their Ångström exponent (AE). These parameters are retrieved with the CALIOP operational method, the POLDER operational polarization method and the CALIOP-based depolarization ratio method (DRM) - for which we also propose a calibrated version (denominated DRMSODA, where SODA is the Synergized Optical Depth of Aerosols). We analyse 6 months of data over three distinctive regions characterized by different types of aerosols and clouds. Additionally, for these regions, we select three case studies: a biomass-burning event over the South Atlantic Ocean, a Saharan dust case over the North Atlantic Ocean and a Siberian biomass-burning event over the North Pacific Ocean. Four and a half years of data are studied over the entire globe for distinct situations where aerosol and cloud layers are in contact or vertically separated. Overall, the regional analysis shows a good correlation between the POLDER and the DRMSODA AOTs when the microphysics of aerosols is dominated by fine-mode particles of biomass-burning aerosols from southern Africa (correlation coefficient (R2) of 0.83) or coarse-mode aerosols of Saharan dust (R2 of 0.82). A good correlation between these methods (R2 of 0.68) is also observed in the global treatment, when the aerosol and cloud layers are separated well. The analysis of detached layers also shows a mean difference in AOT of 0.07 at 532 nm between POLDER and DRMSODA at a global scale. The correlation between the retrievals decreases when a complex mixture of aerosols is expected (R2 of 0.37) - as in the

  9. Role of volcanic and anthropogenic aerosols in the recent global surface warming slowdown

    Science.gov (United States)

    Smith, Doug M.; Booth, Ben B. B.; Dunstone, Nick J.; Eade, Rosie; Hermanson, Leon; Jones, Gareth S.; Scaife, Adam A.; Sheen, Katy L.; Thompson, Vikki

    2016-10-01

    The rate of global mean surface temperature (GMST) warming has slowed this century despite the increasing concentrations of greenhouse gases. Climate model experiments show that this slowdown was largely driven by a negative phase of the Pacific Decadal Oscillation (PDO), with a smaller external contribution from solar variability, and volcanic and anthropogenic aerosols. The prevailing view is that this negative PDO occurred through internal variability. However, here we show that coupled models from the Fifth Coupled Model Intercomparison Project robustly simulate a negative PDO in response to anthropogenic aerosols implying a potentially important role for external human influences. The recovery from the eruption of Mount Pinatubo in 1991 also contributed to the slowdown in GMST trends. Our results suggest that a slowdown in GMST trends could have been predicted in advance, and that future reduction of anthropogenic aerosol emissions, particularly from China, would promote a positive PDO and increased GMST trends over the coming years. Furthermore, the overestimation of the magnitude of recent warming by models is substantially reduced by using detection and attribution analysis to rescale their response to external factors, especially cooling following volcanic eruptions. Improved understanding of external influences on climate is therefore crucial to constrain near-term climate predictions.

  10. Trends in Particle-phase Liquid Water Measurements During the Southern Oxidant and Aerosol Study

    Science.gov (United States)

    Nguyen, T. V.; Petters, M. D.; Carlton, A. G.; Suda, S.

    2013-12-01

    Particle-phase liquid water (H2Optcl) contributes to total aerosol mass concentrations. Previous studies established links between inorganic species, particle hygroscopicity, ambient relative humidity, and condensed phase liquid water. These relationships are also included in thermodynamic modules of atmospheric chemistry models. Conversely, relationships between H2Optcl and organic species are poorly understood, and there are few field measurements linking the two. In this study, we present in situ measurements of H2Optcl using a newly developed technique - the semi-volatile differential mobility analysis (SVDMA). Measurements were conducted June 1 - July 15, 2013, during the Southern Oxidant and Aerosol Study (SOAS) in the southeast U.S., a biogenically dominated and photochemically active environment impacted by anthropogenic pollution and known to contain high concentrations of organic aerosol mass. The SVDMA measures volume distributions of ambient atmospheric aerosols in three states: unperturbed, dried, and dried then re-humidified. Unperturbed measurements characterize the aerosol distribution at ambient conditions. For dry spectra, the sample is routed through a cold trap (ΔT = -30K) upstream of the DMA inlet. The total volume of water and semi-volatile organic compounds (SVOCs) lost during drying is quantified by differencing dry and unperturbed volumes from the integrated size spectra, while SVOC volumes are quantified by re-humidifying the sample and referencing to the unperturbed state. Results indicate that liquid water is an important contributor to ambient aerosol volume in the southeast U.S. during the early morning period when the relative humidity differential is largest. Measured H2Optcl volumes can be characterized by hygroscopicity parameter κ ranging from 0.2 to 0.3, which is consistent with a mix of hygroscopic organic and inorganic compounds. Both H2Optcl and κ peak in the early morning when ambient relative humidity is decreasing

  11. Retrieval of aerosol microphysical and optical properties above liquid clouds from POLDER/PARASOL polarization measurements

    Directory of Open Access Journals (Sweden)

    F. Waquet

    2013-04-01

    Full Text Available Most of the current aerosol retrievals from passive sensors are restricted to cloud-free scenes, which strongly reduces our ability to monitor the aerosol properties at a global scale and to estimate their radiative forcing. The presence of aerosol above clouds (AAC affects the polarized light reflected by the cloud layer, as shown by the spaceborne measurements provided by the POlarization and Directionality of Earth Reflectances (POLDER instrument on the PARASOL satellite. In a previous work, a first retrieval method was developed for AAC scenes and evaluated for biomass-burning aerosols transported over stratocumulus clouds. The method was restricted to the use of observations acquired at forward scattering angles (90–120° where polarized measurements are highly sensitive to fine-mode particle scattering. Non-spherical particles in the coarse mode, such as mineral dust particles, do not much polarize light and cannot be handled with this method. In this paper, we present new developments that allow retrieving also the properties of mineral dust particles above clouds. These particles do not much polarize light but strongly reduce the polarized cloud bow generated by the liquid cloud layer beneath and observed for scattering angles around 140°. The spectral attenuation can be used to qualitatively identify the nature of the particles (i.e. accumulation mode versus coarse mode, i.e. mineral dust particles versus biomass-burning aerosols, whereas the magnitude of the attenuation is related to the optical thickness of the aerosol layer. We also use the polarized measurements acquired in the cloud bow to improve the retrieval of both the biomass-burning aerosol properties and the cloud microphysical properties. We provide accurate polarized radiance calculations for AAC scenes and evaluate the contribution of the POLDER polarization measurements for the simultaneous retrieval of the aerosol and cloud properties. We investigate various scenes

  12. A technique for the measurement of organic aerosol hygroscopicity, oxidation level, and volatility distributions

    Science.gov (United States)

    Cain, Kerrigan P.; Pandis, Spyros N.

    2017-12-01

    Hygroscopicity, oxidation level, and volatility are three crucial properties of organic pollutants. This study assesses the feasibility of a novel measurement and analysis technique to determine these properties and establish their relationship. The proposed experimental setup utilizes a cloud condensation nuclei (CCN) counter to quantify hygroscopic activity, an aerosol mass spectrometer to measure the oxidation level, and a thermodenuder to evaluate the volatility. The setup was first tested with secondary organic aerosol (SOA) formed from the ozonolysis of α-pinene. The results of the first experiments indicated that, for this system, the less volatile SOA contained species that had on average lower O : C ratios and hygroscopicities. In this SOA system, both low- and high-volatility components can have comparable oxidation levels and hygroscopicities. The method developed here can be used to provide valuable insights about the relationships among organic aerosol hygroscopicity, oxidation level, and volatility.

  13. Aerosol characterization study using multi-spectrum remote sensing measurement techniques.

    Energy Technology Data Exchange (ETDEWEB)

    Glen, Crystal Chanea; Sanchez, Andres L.; Lucero, Gabriel Anthony; Schmitt, Randal L.; Johnson, Mark S.; Tezak, Matthew S; Servantes, Brandon Lee

    2013-09-01

    A unique aerosol flow chamber coupled with a bistatic LIDAR system was implemented to measure the optical scattering cross sections and depolarization ratio of common atmospheric particulates. Each of seven particle types (ammonium sulfate, ammonium nitrate, sodium chloride, potassium chloride, black carbon and Arizona road dust) was aged by three anthropogenically relevant mechanisms: 1. Sulfuric acid deposition, 2. Toluene ozonolysis reactions, and 3. m-Xylene ozonolysis reactions. The results of pure particle scattering properties were compared with their aged equivalents. Results show that as most particles age under industrial plume conditions, their scattering cross sections are similar to pure black carbon, which has significant impacts to our understanding of aerosol impacts on climate. In addition, evidence emerges that suggest chloride-containing aerosols are chemically altered during the organic aging process. Here we present the direct measured scattering cross section and depolarization ratios for pure and aged atmospheric particulates.

  14. Techniques for measuring aerosol attenuation using the Central Laser Facility at the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Collaboration, The Pierre Auger

    2013-04-01

    The Pierre Auger Observatory in Malargüe, Argentina, is designed to study the properties of ultra-high energy cosmic rays with energies above 10(18)eV. It is a hybrid facility that employs a Fluorescence Detector to perform nearly calorimetric measurements of Extensive Air Shower energies. To obtain reliable calorimetric information from the FD, the atmospheric conditions at the observatory need to be continuously monitored during data acquisition. In particular, light attenuation due to aerosols is an important atmospheric correction. The aerosol concentration is highly variable, so that the aerosol attenuation needs to be evaluated hourly. We use light from the Central Laser Facility, located near the center of the observatory site, having an optical signature comparable to that of the highest energy showers detected by the FD. This paper presents two procedures developed to retrieve the aerosol attenuation of fluorescence light from CLF laser shots. Cross checks between the two methods demonstrate that results from both analyses are compatible, and that the uncertainties are well understood. The measurements of the aerosol attenuation provided by the two procedures are currently used at the Pierre Auger Observatory to reconstruct air shower data.

  15. The SPARC Aerosol Assessment

    Science.gov (United States)

    Hamill, P.; Thomason, L. W.; Peter, T.

    2002-05-01

    Stratospheric Processes and their Role in Climate (SPARC), a project of the WMO/ICSU/IOC World Climate Research Programme, was responsible for the recent SPARC Assessment of Upper Tropospheric and Stratospheric Water Vapour. SPARC has now decided to generate an analogous document for the stratospheric aerosol, using many of the measurements that have been developed in the last twenty years, but relying heavily on the SAGE II data set. The stratospheric aerosol assessment involves a large international collection of atmospheric scientists whose special area of expertise is the stratospheric aerosol. Key questions that have been identified as requiring answers include: How have aerosol properties such as surface area density varied with time? How representative are satellite-based climatologies? What is the non-volcanic bacground for stratospheric aerosol and can a trend in it be detected? How well can models reproduce observed aerosol properties? We report on the ``kickoff" workshop that was held at the CNES headquarters in Paris on November 4-6, 2001. We shall describe some of the interesting results that were based on the SAGE II data set. The assessment will be carried out by five working groups each focussing on one of the following aspects: processes, aerosol precursors, climatology, trends and modeling. The long records from SAGE II, HALOE and other space based instruments will play a prominent role in construction of a climatology. It is expected that a valuable result of this assessment will be a set of ``standard" stratospheric aerosol parameters for use by modelers.

  16. iSPEX: everybody can measure atmospheric aerosols with a smartphone spectropolarimeter

    Science.gov (United States)

    Snik, F.; Heikamp, S.; de Boer, J.; Keller, C. U.; van Harten, G.; Smit, J. M.; Rietjens, J. H. H.; Hasekamp, O.; Stam, D. M.; Volten, H.; iSPEX Team

    2012-04-01

    An increasing amount people carry a mobile phone with internet connection, camera and large computing power. iSPEX, a spectropolarimetric add-on with complementary app, instantly turns a smartphone into a scientific instrument to measure dust and other aerosols in our atmosphere. A measurement involves scanning the blue sky, which yields the angular behavior of the degree of linear polarization as a function of wavelength, which can unambiguously be interpreted in terms of size, shape and chemical composition of the aerosols in the sky directly above. The measurements are tagged with location and pointing information, and submitted to a central database where they will be interpreted and compiled into an aerosol map. Through crowdsourcing, many people will thus be able to contribute to a better assessment of health risks of particulate matter and of whether or not volcanic ash clouds are dangerous for air traffic. It can also contribute to the understanding of the relationship between atmospheric aerosols and climate change. We will give a live presentation of the first iSPEX prototype. Furthermore, we will present the design and the plans for producing the iSPEX add-on, app and website. We aim to distribute thousands of iSPEX units, such that a unique network of aerosol measurement equipment is created. Many people will thus contribute to the solution of several urgent social and scientific problems, and learn about the nature of light, remote sensing and the issues regarding atmospheric aerosols in the process. In particular we focus on school classes where smartphones are usually considered a nuisance, whereas now they can be a crucial part of various educational programs in science class.

  17. Aerosol source apportionment from 1-year measurements at the CESAR tower in Cabauw, the Netherlands

    Directory of Open Access Journals (Sweden)

    P. Schlag

    2016-07-01

    Full Text Available Intensive measurements of submicron aerosol particles and their chemical composition were performed with an Aerosol Chemical Speciation Monitor (ACSM at the Cabauw Experimental Site for Atmospheric Research (CESAR in Cabauw, the Netherlands, sampling at 5 m height above ground. The campaign lasted nearly 1 year from July 2012 to June 2013 as part of the EU-FP7-ACTRIS project (Q-ACSM Network. Including equivalent black carbon an average particulate mass concentration of 9.50 µg m−3 was obtained during the whole campaign with dominant contributions from ammonium nitrate (45 %, organic aerosol (OA, 29 %, and ammonium sulfate (19 %. There were 12 exceedances of the World Health Organization (WHO PM2.5 daily mean limit (25 µg m−3 observed at this rural site using PM1 instrumentation only. Ammonium nitrate and OA represented the largest contributors to total particulate matter during periods of exceedance. Source apportionment of OA was performed season-wise by positive matrix factorization (PMF using the multilinear engine 2 (ME-2 controlled via the source finder (SoFi. Primary organic aerosols were attributed mainly to traffic (8–16 % contribution to total OA, averaged season-wise and biomass burning (0–23 %. Secondary organic aerosols (SOAs, 61–84 % dominated the organic fraction during the whole campaign, particularly on days with high mass loadings. A SOA factor which is attributed to humic-like substances (HULIS was identified as a highly oxidized background aerosol in Cabauw. This shows the importance of atmospheric aging processes for aerosol concentration at this rural site. Due to the large secondary fraction, the reduction of particulate mass at this rural site is challenging on a local scale.

  18. From BASE-ASIA Toward 7-SEAS: A Satellite-Surface Perspective of Boreal Spring Biomass-Burning Aerosols and Clouds in Southeast Asia

    Science.gov (United States)

    Tsay, Si-Chee; Hsu, N. Christina; Lau, William K.-M.; Li, Can; Gabriel, Philip M.; Ji, Qiang; Holben, Brent N.; Welton, E. Judd; Nguyen, Anh X.; Janjai, Serm; hide

    2013-01-01

    In this paper, we present recent field studies conducted by NASA's SMART-COMMIT (and ACHIEVE, to be operated in 2013) mobile laboratories, jointly with distributed ground-based networks (e.g., AERONET, http://aeronet.gsfc.nasa.gov/ and MPLNET, http://mplnet.gsfc.nasa.gov/) and other contributing instruments over northern Southeast Asia. These three mobile laboratories, collectively called SMARTLabs (cf. http://smartlabs.gsfc.nasa.gov/, Surface-based Mobile Atmospheric Research & Testbed Laboratories) comprise a suite of surface remote sensing and in-situ instruments that are pivotal in providing high spectral and temporal measurements, complementing the collocated spatial observations from various Earth Observing System (EOS) satellites. A satellite-surface perspective and scientific findings, drawn from the BASE-ASIA (2006) field deployment as well as a series of ongoing 7-SEAS (2010-13) field activities over northern Southeast Asia are summarized, concerning (i) regional properties of aerosols from satellite and in situ measurements, (ii) cloud properties from remote sensing and surface observations, (iii) vertical distribution of aerosols and clouds, and (iv) regional aerosol radiative effects and impact assessment. The aerosol burden over Southeast Asia in boreal spring, attributed to biomass burning, exhibits highly consistent spatial and temporal distribution patterns, with major variability arising from changes in the magnitude of the aerosol loading mediated by processes ranging from large-scale climate factors to diurnal meteorological events. Downwind from the source regions, the tightly coupled-aerosolecloud system provides a unique, natural laboratory for further exploring the micro- and macro-scale relationships of the complex interactions. The climatic significance is presented through large-scale anti-correlations between aerosol and precipitation anomalies, showing spatial and seasonal variability, but their precise cause-and-effect relationships

  19. Optimal Estimation-Based Algorithm to Retrieve Aerosol Optical Properties for GEMS Measurements over Asia

    Directory of Open Access Journals (Sweden)

    Mijin Kim

    2018-01-01

    Full Text Available The Geostationary Environment Monitoring Spectrometer (GEMS is scheduled to be in orbit in 2019 onboard the GEO-KOMPSAT 2B satellite and will continuously monitor air quality over Asia. The GEMS will make measurements in the UV spectrum (300–500 nm with 0.6 nm resolution. In this study, an algorithm is developed to retrieve aerosol optical properties from UV-visible measurements for the future satellite instrument and is tested using 3 years of existing OMI L1B data. This algorithm provides aerosol optical depth (AOD, single scattering albedo (SSA and aerosol layer height (ALH using an optimized estimation method. The retrieved AOD shows good correlation with Aerosol Robotic Network (AERONET AOD with correlation coefficients of 0.83, 0.73 and 0.80 for heavy-absorbing fine (HAF particles, dust and non-absorbing (NA particles, respectively. However, regression tests indicate underestimation and overestimation of HAF and NA AOD, respectively. In comparison with AOD from the OMI/Aura Near-UV Aerosol Optical Depth and Single Scattering Albedo 1-orbit L2 Swath 13 km × 24 km V003 (OMAERUV algorithm, the retrieved AOD has a correlation coefficient of 0.86 and linear regression equation, AODGEMS = 1.18AODOMAERUV + 0.09. An uncertainty test based on a reference method, which estimates retrieval error by applying the algorithm to simulated radiance data, revealed that assumptions in the spectral dependency of aerosol absorptivity in the UV cause significant errors in aerosol property retrieval, particularly the SSA retrieval. Consequently, retrieved SSAs did not show good correlation with AERONET values. The ALH results were qualitatively compared with the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP products and were found to be well correlated for highly absorbing aerosols. The difference between the attenuated-backscatter-weighted height from CALIOP and retrieved ALH were mostly closed to zero when the retrieved AOD is higher than 0.8 and

  20. SURFACE CHEMISTRY AND PARTICLE SHAPE: PROCESSES FOR THE EVOLUTION OF AEROSOLS IN TITAN's ATMOSPHERE

    International Nuclear Information System (INIS)

    Lavvas, P.; Imanaka, H.; Sander, M.; Kraft, M.

    2011-01-01

    We use a stochastic approach in order to investigate the production and evolution of aerosols in Titan's atmosphere. The simulation initiates from the benzene molecules observed in the thermosphere and follows their evolution to larger aromatic structures through reaction with gas-phase radical species. Aromatics are allowed to collide and provide the first primary particles, which further grow to aggregates through coagulation. We also consider for the first time the contribution of heterogenous processes at the surface of the particles, which are described by the deposition of the formed aromatic structures on the surface of the particles, and also through the chemical reaction with radical species. Our results demonstrate that the evolution of aerosols in terms of size, shape, and density is a result of competing processes between surface growth, coagulation, and sedimentation. Furthermore, our simulations clearly demonstrate the presence of a spherical growth region in the upper atmosphere followed by a transition to an aggregate growth region below. The transition altitude ranges between 500 and 600 km based on the parameters of the simulation.

  1. Viral contamination of aerosol and surfaces through toilet use in health care and other settings.

    Science.gov (United States)

    Verani, Marco; Bigazzi, Roberto; Carducci, Annalaura

    2014-07-01

    The airborne spreading of enteric viruses can occur through the aerosol and droplets produced by toilet flushing. These can contaminate the surrounding environment, but few data exist to estimate the risk of exposure and infection. For this reason environmental monitoring of air and selected surfaces was carried out in 2 toilets of an office building and in 3 toilets of a hospital before and after cleaning operations. To reveal the presence of norovirus, enterovirus, rhinovirus, human rotavirus, and Torque teno virus and to quantify human adenovirus and bacteria counts, molecular and cultural methods were used. On the whole, viruses were detected on 78% of surfaces and in 81% of aerosol. Among the researched viruses, only human adenovirus and Torque teno virus were found in both surface and air samples. In several cases the same adenovirus strain was concurrently found in all matrices. Bacterial counts were unrelated to viral presence and cleaning did not seem to substantially reduce contamination. The data collected in our study confirm that toilets are an important source of viral contamination, mainly in health care settings, where disinfection can have a crucial role in preventing virus spread. Copyright © 2014 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

  2. Measurements of Near Sea Surface Infrared Propagation

    National Research Council Canada - National Science Library

    Frost, Shaun

    1999-01-01

    .... Measurements have been made of the atmospheric infrared transmission near the sea surface. Spectral transmission profiles were measured for a number of ranges using a fourier transform spectrometer...

  3. The measurement of surface gravity

    International Nuclear Information System (INIS)

    Crossley, David; Hinderer, Jacques; Riccardi, Umberto

    2013-01-01

    This review covers basic theory and techniques behind the use of ground-based gravimetry at the Earth's surface. The orientation is toward modern instrumentation, data processing and interpretation for observing surface, land-based, time-variable changes to the geopotential. The instrumentation side is covered in some detail, with specifications and performance of the most widely used models of the three main types: the absolute gravimeters (FG5, A10 from Micro-g LaCoste), superconducting gravimeters (OSG, iGrav from GWR instruments), and the new generation of spring instruments (Micro-g LaCoste gPhone, Scintrex CG5 and Burris ZLS). A wide range of applications is covered, with selected examples from tides and ocean loading, atmospheric effects on gravity, local and global hydrology, seismology and normal modes, long period and tectonics, volcanology, exploration gravimetry, and some examples of gravimetry connected to fundamental physics. We show that there are only a modest number of very large signals, i.e. hundreds of µGal (10 −8 m s −2 ), that are easy to see with all gravimeters (e.g. tides, volcanic eruptions, large earthquakes, seasonal hydrology). The majority of signals of interest are in the range 0.1–5.0 µGal and occur at a wide range of time scales (minutes to years) and spatial extent (a few meters to global). Here the competing effects require a careful combination of different gravimeter types and measurement strategies to efficiently characterize and distinguish the signals. Gravimeters are sophisticated instruments, with substantial up-front costs, and they place demands on the operators to maximize the results. Nevertheless their performance characteristics such as drift and precision have improved dramatically in recent years, and their data recording ability and ruggedness have seen similar advances. Many subtle signals are now routinely connected with known geophysical effects such as coseismic earthquake displacements, post

  4. The measurement of surface gravity

    Science.gov (United States)

    Crossley, David; Hinderer, Jacques; Riccardi, Umberto

    2013-04-01

    This review covers basic theory and techniques behind the use of ground-based gravimetry at the Earth's surface. The orientation is toward modern instrumentation, data processing and interpretation for observing surface, land-based, time-variable changes to the geopotential. The instrumentation side is covered in some detail, with specifications and performance of the most widely used models of the three main types: the absolute gravimeters (FG5, A10 from Micro-g LaCoste), superconducting gravimeters (OSG, iGrav from GWR instruments), and the new generation of spring instruments (Micro-g LaCoste gPhone, Scintrex CG5 and Burris ZLS). A wide range of applications is covered, with selected examples from tides and ocean loading, atmospheric effects on gravity, local and global hydrology, seismology and normal modes, long period and tectonics, volcanology, exploration gravimetry, and some examples of gravimetry connected to fundamental physics. We show that there are only a modest number of very large signals, i.e. hundreds of µGal (10-8 m s-2), that are easy to see with all gravimeters (e.g. tides, volcanic eruptions, large earthquakes, seasonal hydrology). The majority of signals of interest are in the range 0.1-5.0 µGal and occur at a wide range of time scales (minutes to years) and spatial extent (a few meters to global). Here the competing effects require a careful combination of different gravimeter types and measurement strategies to efficiently characterize and distinguish the signals. Gravimeters are sophisticated instruments, with substantial up-front costs, and they place demands on the operators to maximize the results. Nevertheless their performance characteristics such as drift and precision have improved dramatically in recent years, and their data recording ability and ruggedness have seen similar advances. Many subtle signals are now routinely connected with known geophysical effects such as coseismic earthquake displacements, post-glacial rebound

  5. Measurements and estimation of the columnar optical depth of tropospheric aerosols in the UV spectral region

    Directory of Open Access Journals (Sweden)

    V. E. Cachorro

    2002-04-01

    Full Text Available We report values of the columnar tropospheric aerosol optical depth at UV wavelengths based on experimental measurements of the direct spectral irradiances carried out by a commercial spectroradiometer (Li1800 of Licor company covering the range from 300–1100 nm at two stations with different climate characteristics in Spain. The first station is located in a rural site in north central Spain with continental climate. The data extend from March to the end of October of 1995. The other station is a coastal site in the Gulf of Cádiz (southwest Spain of maritime climate type. This study is mainly focused on the capability of estimating aerosol optical depth values in the UV region based on the extracted information in the visible and near infrared ranges. A first method has been used based on the Ångström turbidity parameters. However, since this method requires detailed spectral information, a second method has also been used, based on the correlation between wavelengths. A correlation has been established between the experimental aerosol optical depth values at 350 nm and 500 nm wavelengths. Although the type of aerosol seems to be the key factor that determines the quality of these estimations, the evaluation of the associated error is necessary to know the behaviour of these estimations in each area of study.Key words. Atmospheric composition and structure (aerosols and particles; transmission and scattering of radiation; troposphere – composition and chemistry

  6. Measurements and estimation of the columnar optical depth of tropospheric aerosols in the UV spectral region

    Directory of Open Access Journals (Sweden)

    V. E. Cachorro

    Full Text Available We report values of the columnar tropospheric aerosol optical depth at UV wavelengths based on experimental measurements of the direct spectral irradiances carried out by a commercial spectroradiometer (Li1800 of Licor company covering the range from 300–1100 nm at two stations with different climate characteristics in Spain. The first station is located in a rural site in north central Spain with continental climate. The data extend from March to the end of October of 1995. The other station is a coastal site in the Gulf of Cádiz (southwest Spain of maritime climate type. This study is mainly focused on the capability of estimating aerosol optical depth values in the UV region based on the extracted information in the visible and near infrared ranges. A first method has been used based on the Ångström turbidity parameters. However, since this method requires detailed spectral information, a second method has also been used, based on the correlation between wavelengths. A correlation has been established between the experimental aerosol optical depth values at 350 nm and 500 nm wavelengths. Although the type of aerosol seems to be the key factor that determines the quality of these estimations, the evaluation of the associated error is necessary to know the behaviour of these estimations in each area of study.

    Key words. Atmospheric composition and structure (aerosols and particles; transmission and scattering of radiation; troposphere – composition and chemistry

  7. The Influence of Stratospheric Sulphate Aerosol Deployment on the Surface Air Temperature and the Risk of an Abrupt Global Warming

    Directory of Open Access Journals (Sweden)

    Roland von Glasow

    2010-12-01

    Full Text Available We used the ‘Radiative-Convective Model of the Earth-atmosphere system’ (OGIM to investigate the cooling effects induced by sulphur injections into the stratosphere. The ensemble of numerical calculations was based on the A1B scenario from the IPCC Special Report on Emissions Scenarios (SRES. Several geoengineered scenarios were analysed, including the abrupt interruption of these injections in different scenarios and at different dates. We focused on the surface air temperature (SAT anomalies induced by stratospheric sulphate aerosol generated in order to compensate future warming. Results show that continuous deployment of sulphur into the stratosphere could induce a lasting decrease in SAT. Retaining a constant aerosol loading equivalent to 6 TgS would delay the expected global warming by 53 years. Keeping the SAT constant in a context of increasing greenhouse gases (GHGs means that the aerosol loading needs to be increased by 1.9% annually. This would offset the effect of increasing GHG under the A1B scenario. A major focus of this study was on the heating rates of SAT that would arise in different scenarios in case of an abrupt cessation of sulphur injections into the stratosphere. Our model results show that heating rates after geoengineering interruption would be 15–28 times higher than in a case without geoengineering, with likely important consequences for life on Earth. Larger initial sulphate loadings induced more intense warming rates when the geoengineering was stopped at the same time. This implies that, if sulphate loading was increased to maintain constant SAT in the light of increasing GHG concentrations, the later the geoengineering interruption was to occur, the higher the heating rates would be. Consequently, geoengineering techniques like this should only be regarded as last-resort measures and require intense further research should they ever become necessary.

  8. Spectral Aerosol Extinction (SpEx): A New Instrument for In situ Ambient Aerosol Extinction Measurements Across the UV/Visible Wavelength Range

    Science.gov (United States)

    Jordan, C. E.; Anderson, B. E.; Beyersdorf, A. J.; Corr, C. A.; Dibb, J. E.; Greenslade, M. E.; Martin, R. F.; Moore, R. H.; Scheuer, E.; Shook, M. A.; hide

    2015-01-01

    We introduce a new instrument for the measurement of in situ ambient aerosol extinction over the 300-700 nm wavelength range, the Spectral Aerosol Extinction (SpEx) instrument. This measurement capability is envisioned to complement existing in situ instrumentation, allowing for simultaneous measurement of the evolution of aerosol optical, chemical, and physical characteristics in the ambient environment. In this work, a detailed description of the instrument is provided along with characterization tests performed in the laboratory. Measured spectra of NO2 and polystyrene latex spheres agreed well with theoretical calculations. Good agreement was also found with simultaneous aerosol extinction measurements at 450, 530, and 630 nm using CAPS PMex instruments in a series of 22 tests including non-absorbing compounds, dusts, soot, and black and brown carbon analogs. SpEx can more accurately distinguish the presence of brown carbon from other absorbing aerosol due to its 300 nm lower wavelength limit compared to measurements limited to visible wavelengths. In addition, the spectra obtained by SpEx carry more information than can be conveyed by a simple power law fit that is typically defined by the use of Angstrom Exponents. Future improvements aim at lowering detection limits and ruggedizing the instrument for mobile operation.

  9. Comparison of aerosol optical thickness retrieval from spectroradiometer measurements and from two radiative transfer models

    Energy Technology Data Exchange (ETDEWEB)

    Utrillas, M.P.; Martinez-Lozano, J.A.; Tena, F. [Universitat de Valencia, Dept. de Termodinamica, Valencia (Spain); Cachorro, V.E. [Universidad de Valladolid, Dept. de Fisica Aplicada 1, Valladolid (Spain); Hernandez, S. [Universidad de Valladolid, Dept. de Ingenieria Agricola y Forestal, Valladolid (Spain)

    2000-07-01

    The spectral values of the aerosol optical thickness {tau}{sub a{lambda}} in the 400-670 nm band have been determined from 500 solar direct irradiance spectra at normal incidence registered at Valencia (Spain) in the period from July 1993 to March 1997. The {tau}{sub a{lambda}} values obtained from experimental measurements have been compared with the boundary layer aerosol models implemented in the radiative transfer codes ZD-LOA and LOWTRAN 7. For the ZD-LOA code, the continental and maritime models have been considered and for the LOWTRAN 7 code the rural, maritime, urban and tropospheric models have been used. The obtained results show that the aerosol model that best represents the average turbidity of the boundary layer for the urban area of Valencia (Spain) is the continental model when the ZD-LOA code is used and the urban model when the LOWTRAN 7 code is used. (Author)

  10. Measurement of mixed biomass burning and mineral dust aerosol in the thermal infrared

    Science.gov (United States)

    Koehler, C. H.; Trautmann, T.; Lindermeir, E.

    2009-03-01

    From January 19th to February 7th, 2008, we installed a Fourier transform infrared spectrometer (FTIR) at Praia Airport on the island of Santiago, Cape Verde. Our goal was to measure the combined radiative effect of biomass burning aerosol and mineral dust usually observed there during that time of the year, when mineral dust emerging from the Sahara mixes with biomass burning aerosol transported north-westwards from the Sahelian region. Our measurements were part of the Saharan Mineral Dwst Experiment 2 (SAMUM 2) funded by the German Research Foundation (DFG) as continuation of the SAMUM field experiment in Morocco in 2006. SAMUM 2 is a joint venture of several German research institutes and universities and included both ground based as well as airborne measurements with the DLR Falcon research aircraft. The ground based instrumentation included spectrometers for visible and thermal infrared downwelling radiation, sun photometers, LIDAR and particle impactors while the Falcon was equipped with LIDAR and several instruments for aerosol analysis and sample return. A comparison of the FTIR measurements with radiative transfer simulations yields the expected aerosol forcing in the atmospheric window region after application of a suitable calibration method.

  11. Enhancements of a mechanical lung simulator for ex vivo measuring of aerosol deposition in lungs

    Czech Academy of Sciences Publication Activity Database

    Steiner, T.; Forjan, M.; Kopp, T.; Bureš, Zbyněk; Drauschke, A.

    2012-01-01

    Roč. 57, Suppl.1 (2012), s. 799-802 ISSN 0013-5585 Institutional research plan: CEZ:AV0Z50390512 Keywords : aerosol measurement * lung simulator Subject RIV: FS - Medical Facilities ; Equipment Impact factor: 1.157, year: 2012

  12. Comparisons of LASE, aircraft, and satellite measurements of aerosol optical properties and water vapor during TARFOX

    NARCIS (Netherlands)

    Ferrare, R.; Ismail, S.; Browell, E.; Brackett, V.; Kooi, S.; Clayton, M.; Hobbs, P.V.; Hartley, S.; Veefkind, J.P.; Russell, P.; Livingston, J.; Tanré, D.; Hignett, P.

    2000-01-01

    We examine aerosol extinction and optical thickness from the Lidar Atmospheric Sensing Experiment (LASE), the in situ nephelometer and absorption photometer on the University of Washington C-131A aircraft, and the NASA Ames Airborne Tracking Sun Photometer (AATS-6) on the C-131A measured during the

  13. Atmospheric aerosol load morphological classification and retrieved visibility based on lidar backscatter measurements

    CSIR Research Space (South Africa)

    Tesfaye, M

    2010-01-01

    Full Text Available of the air mass that arrived at the measurement site was traced back using online HYSPLIT model. The visibility range has been calculated and presented, using average aerosol extinction co-efficient profile and assuming that the atmosphere is homogeneous...

  14. Advances In Global Aerosol Modeling Applications Through Assimilation of Satellite-Based Lidar Measurements

    Science.gov (United States)

    Campbell, James; Hyer, Edward; Zhang, Jianglong; Reid, Jeffrey; Westphal, Douglas; Xian, Peng; Vaughan, Mark

    2010-05-01

    Modeling the instantaneous three-dimensional aerosol field and its downwind transport represents an endeavor with many practical benefits foreseeable to air quality, aviation, military and science agencies. The recent proliferation of multi-spectral active and passive satellite-based instruments measuring aerosol physical properties has served as an opportunity to develop and refine the techniques necessary to make such numerical modeling applications possible. Spurred by high-resolution global mapping of aerosol source regions, and combined with novel multivariate data assimilation techniques designed to consider these new data streams, operational forecasts of visibility and aerosol optical depths are now available in near real-time1. Active satellite-based aerosol profiling, accomplished using lidar instruments, represents a critical element for accurate analysis and transport modeling. Aerosol source functions, alone, can be limited in representing the macrophysical structure of injection scenarios within a model. Two-dimensional variational (2D-VAR; x, y) assimilation of aerosol optical depth from passive satellite observations significantly improves the analysis of the initial state. However, this procedure can not fully compensate for any potential vertical redistribution of mass required at the innovation step. The expense of an inaccurate vertical analysis of aerosol structure is corresponding errors downwind, since trajectory paths within successive forecast runs will likely diverge with height. In this paper, the application of a newly-designed system for 3D-VAR (x,y,z) assimilation of vertical aerosol extinction profiles derived from elastic-scattering lidar measurements is described [Campbell et al., 2009]. Performance is evaluated for use with the U. S. Navy Aerosol Analysis and Prediction System (NAAPS) by assimilating NASA/CNES satellite-borne Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) 0.532 μm measurements [Winker et al., 2009

  15. Quantitative measurement of aerosol deposition on skin, hair and clothing for dosimetric assessment

    Energy Technology Data Exchange (ETDEWEB)

    Roed, J.; Andersson, J.G.; Bell, K.F.; Byrne, M.A.; Fogh, C.L.; Goddard, A.J.H.; Vollmair, D.V.

    1998-01-01

    The deposition to human body surfaces of potentially hazardous aerosol has been investigated through tracer experiments. Particles of different sizes labelled with neutron activatable rare earth tracers were released in test rooms and deposited on volunteers. Various sampling techniques to examine the clearance and retention of the aerosol to skin, hair and clothing were investigated, and a protocol for the most efficient procedure was established and validated. Experiments indicate that the deposition velocity to skin increases linearly with the particle size. A wind tunnel experiment simulating outdoor conditions showed outdoor deposition velocities to be almost an order of magnitude higher than those recorded indoors. Both in vivo and in vitro experiments were conducted, and the influence of various factors, such as surface type, air flow, heating and electrostatics were examined. The dynamics of particle removal from human skin were studied by fluorescence scanning. Using the experimentally determined parameters, a model was established for calculation of radiation doses received from deposition of airborne radioactive aerosol on human body surfaces. It was found that the gamma doses that could be expected from deposition on skin were of the same order of magnitude as the gamma doses received over several years from contamination on outdoor surfaces. Assuming very high dry contamination levels, as were recorded in some areas of Russia after the Chernobyl accident, it was found that beta doses from skin deposition may amount to several Sievert and thus be responsible for a significant cancer risk. (au). 12 tabs., 9 ills., 43 refs.

  16. Quantitative measurement of aerosol deposition on skin, hair and clothing for dosimetric assessment

    International Nuclear Information System (INIS)

    Roed, J.; Andersson, J.G.; Bell, K.F.; Byrne, M.A.; Fogh, C.L.; Goddard, A.J.H.; Vollmair, D.V.

    1998-01-01

    The deposition to human body surfaces of potentially hazardous aerosol has been investigated through tracer experiments. Particles of different sizes labelled with neutron activatable rare earth tracers were released in test rooms and deposited on volunteers. Various sampling techniques to examine the clearance and retention of the aerosol to skin, hair and clothing were investigated, and a protocol for the most efficient procedure was established and validated. Experiments indicate that the deposition velocity to skin increases linearly with the particle size. A wind tunnel experiment simulating outdoor conditions showed outdoor deposition velocities to be almost an order of magnitude higher than those recorded indoors. Both in vivo and in vitro experiments were conducted, and the influence of various factors, such as surface type, air flow, heating and electrostatics were examined. The dynamics of particle removal from human skin were studied by fluorescence scanning. Using the experimentally determined parameters, a model was established for calculation of radiation doses received from deposition of airborne radioactive aerosol on human body surfaces. It was found that the gamma doses that could be expected from deposition on skin were of the same order of magnitude as the gamma doses received over several years from contamination on outdoor surfaces. Assuming very high dry contamination levels, as were recorded in some areas of Russia after the Chernobyl accident, it was found that beta doses from skin deposition may amount to several Sievert and thus be responsible for a significant cancer risk. (au)

  17. The influence of fog parameters on aerosol depletion measured in the KAEVER experiments

    International Nuclear Information System (INIS)

    Poss, G.; Weber, D.; Fritsche, B.

    1995-01-01

    The release of radioactive aerosols in the environment is one of the most serious hazards in case of an accident in nuclear power plant. Many efforts have been made in the past in numerous experimental programs like NSPP, DEMONA, VANAM, LACE, MARVIKEN, others are still underway to improve the knowledge of the aerosol behavior and depletion in a reactor containment in order to estimate the possible source term and to validate computer codes. In the German single compartment KAEVER facility the influence of size distribution, morphology, composition and solubility on the aerosol behavior is investigated. One of the more specific items is to learn about open-quotes wet depletionclose quotes means, the aerosol depletion behavior in condensing atmospheres. There are no experiments known where the fog parameters like droplet size distribution, volume concentration, respectively airborne liquid water content have been measured in- and on-line explicitly. To the authors knowledge the use of the Battelle FASP photometer, which was developed especially for this reason, for the first time gives insight in condensation behavior under accident typical thermal hydraulic conditions. It delivers a basis for code validation in terms of a real comparison of measurements and calculations. The paper presents results from open-quotes wet depletionclose quotes aerosol experiments demonstrating how depletion velocity depends on the fog parameters and where obviously critical fog parameter seem to change the regime from a open-quotes pseudo dry depletionclose quotes at a relative humidity of 100% but quasi no or very low airborne liquid water content to a real open-quotes wet depletionclose quotes under the presence of fogs with varying densities. Characteristics are outlined how soluble and insoluble particles as well as aerosol mixtures behave under condensing conditions

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

    Science.gov (United States)

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

    2016-04-01

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

  19. Modeling and measurements of urban aerosol processes on the neighborhood scale in Rotterdam, Oslo and Helsinki

    Science.gov (United States)

    Karl, Matthias; Kukkonen, Jaakko; Keuken, Menno P.; Lützenkirchen, Susanne; Pirjola, Liisa; Hussein, Tareq

    2016-04-01

    This study evaluates the influence of aerosol processes on the particle number (PN) concentrations in three major European cities on the temporal scale of 1 h, i.e., on the neighborhood and city scales. We have used selected measured data of particle size distributions from previous campaigns in the cities of Helsinki, Oslo and Rotterdam. The aerosol transformation processes were evaluated using the aerosol dynamics model MAFOR, combined with a simplified treatment of roadside and urban atmospheric dispersion. We have compared the model predictions of particle number size distributions with the measured data, and conducted sensitivity analyses regarding the influence of various model input variables. We also present a simplified parameterization for aerosol processes, which is based on the more complex aerosol process computations; this simple model can easily be implemented to both Gaussian and Eulerian urban dispersion models. Aerosol processes considered in this study were (i) the coagulation of particles, (ii) the condensation and evaporation of two organic vapors, and (iii) dry deposition. The chemical transformation of gas-phase compounds was not taken into account. By choosing concentrations and particle size distributions at roadside as starting point of the computations, nucleation of gas-phase vapors from the exhaust has been regarded as post tail-pipe emission, avoiding the need to include nucleation in the process analysis. Dry deposition and coagulation of particles were identified to be the most important aerosol dynamic processes that control the evolution and removal of particles. The error of the contribution from dry deposition to PN losses due to the uncertainty of measured deposition velocities ranges from -76 to +64 %. The removal of nanoparticles by coagulation enhanced considerably when considering the fractal nature of soot aggregates and the combined effect of van der Waals and viscous interactions. The effect of condensation and

  20. An exploratory study on the aerosol height retrieval from OMI measurements of the 477 nm O2 - O2 spectral band using a neural network approach

    Science.gov (United States)

    Chimot, Julien; Pepijn Veefkind, J.; Vlemmix, Tim; de Haan, Johan F.; Amiridis, Vassilis; Proestakis, Emmanouil; Marinou, Eleni; Levelt, Pieternel F.

    2017-03-01

    This paper presents an exploratory study on the aerosol layer height (ALH) retrieval from the OMI 477 nm O2 - O2 spectral band. We have developed algorithms based on the multilayer perceptron (MLP) neural network (NN) approach and applied them to 3-year (2005-2007) OMI cloud-free scenes over north-east Asia, collocated with MODIS Aqua aerosol product. In addition to the importance of aerosol altitude for climate and air quality objectives, our long-term motivation is to evaluate the possibility of retrieving ALH for potential future improvements of trace gas retrievals (e.g. NO2, HCHO, SO2) from UV-visible air quality satellite measurements over scenes including high aerosol concentrations. This study presents a first step of this long-term objective and evaluates, from a statistic point of view, an ensemble of OMI ALH retrievals over a long time period of 3 years covering a large industrialized continental region. This ALH retrieval relies on the analysis of the O2 - O2 slant column density (SCD) and requires an accurate knowledge of the aerosol optical thickness, τ. Using MODIS Aqua τ(550 nm) as a prior information, absolute seasonal differences between the LIdar climatology of vertical Aerosol Structure for space-based lidar simulation (LIVAS) and average OMI ALH, over scenes with MODIS τ(550 nm) ≥ 1. 0, are in the range of 260-800 m (assuming single scattering albedo ω0 = 0. 95) and 180-310 m (assuming ω0 = 0. 9). OMI ALH retrievals depend on the assumed aerosol single scattering albedo (sensitivity up to 660 m) and the chosen surface albedo (variation less than 200 m between OMLER and MODIS black-sky albedo). Scenes with τ ≤ 0. 5 are expected to show too large biases due to the little impact of particles on the O2 - O2 SCD changes. In addition, NN algorithms also enable aerosol optical thickness retrieval by exploring the OMI reflectance in the continuum. Comparisons with collocated MODIS Aqua show agreements between -0. 02 ± 0. 45 and -0. 18 ± 0

  1. Measurement of the atmospheric aerosol particle size distribution in a highly polluted mega-city in Southeast Asia (Dhaka-Bangladesh)

    Science.gov (United States)

    Salam, Abdus; Mamoon, Hassan Al; Ullah, Md. Basir; Ullah, Shah M.

    2012-11-01

    Aerosol particle size distribution was measured with an aerodynamic particle sizer (APS) spectrometer continuously from January 21 to April 24, 2006 in Dhaka, Bangladesh. Particles number, surface and mass distributions data were stored automatically with Aerosol Instrument Manager (AIM) software on average every half an hour in a computer attached to the APS. The grand total average of number, surface and mass concentrations were 8.2 × 103 ± 7.8 × 103 particles cm-3, 13.3 × 103 ± 11.8 × 103 μm2 cm-3 and 3.04 ± 2.10 mg m-3, respectively. Fine particles with diameter smaller than 1.0 μm aerodynamic diameter (AD) dominated the number concentration, accounted for 91.7% of the total particles indicating vehicular emissions were dominating in Dhaka air either from fossil fuel burning or compressed natural gas (CNGs). The surface and mass concentrations between 0.5 and 1.0 μm AD were about 56.0% and 26.4% of the total particles, respectively. Remarkable seasonal differences were observed between winter and pre-monsoon seasons with the highest monthly average in January and the lowest in April. Aerosol particles in winter were 3.79 times higher for number, 3.15 times for surface and 2.18 times for mass distributions than during the pre-monsoon season. Weekends had lower concentrations than weekdays due to less vehicular traffic in the streets. Aerosol particles concentrations were about 15.0% (ranging from 9.4% to 17.3%) higher during traffic peak hours (6:00am-8:00pm) than off hours (8:00pm-6:00am). These are the first aerosol size distribution measurements with respect to number, surface and mass concentrations in real time at Dhaka, Bangladesh.

  2. Investigation of aerosol effects on shallow marine convection - Lidar measurements during NARVAL-I and NARVAL-II

    Science.gov (United States)

    Groß, Silke; Wirth, Martin; Gutleben, Manuel; Ewald, Florian; Kiemle, Christoph; Kölling, Tobias; Mayer, Bernhard

    2017-04-01

    Clouds and aerosols have a large impact on the Earth's radiation budget by scattering and absorption of solar and terrestrial radiation. Furthermore aerosols can modify cloud properties and distribution. Up to now no sufficient understanding in aerosol-cloud interaction and in climate feedback of clouds is achieved. Especially shallow marine convection in the trade wind regions show large uncertainties in climate feedback. Thus a better understanding of these shallow marine convective clouds and how aerosols affect these clouds, e.g. by changing the cloud properties and distribution, is highly demanded. During NARVAL-I (Next-generation airborne remote-sensing for validation studies) and NARVAL-II a set of active and passive remote sensing instruments, i.e. a cloud radar, an aerosol and water vapor lidar system, microwave radiometer, a hyper spectral imager (NARVAL-II only) and radiation measurements, were installed on the German research aircraft HALO. Measurements were performed out of Barbados over the tropical North-Atlantic region in December 2013 and August 2016 to study shallow trade wind convection as well as its environment in the dry and wet season. While no or only few aerosol layers were observed above the marine boundary layer during the dry season in December 2013, part of the measurement area was influenced by high aerosol load caused by long-range transport of Saharan dust during the NARVAL-II measurements in August 2016. Measurement flights during NARVAL-II were conducted the way that we could probed aerosol influenced regions as well as areas with low aerosol load. Thus the measurements during both campaigns provide the opportunity to investigate if and how the transported aerosol layers change the distribution and formation of the shallow marine convection by altering their properties and environment. In our presentation we will focus on the lidar measurements performed during NARVAL-I and NARVAL-II. We will give an overview of the measurements

  3. Recovery efficiency and limit of detection of aerosolized Bacillus anthracis Sterne from environmental surface samples.

    Science.gov (United States)

    Estill, Cheryl Fairfield; Baron, Paul A; Beard, Jeremy K; Hein, Misty J; Larsen, Lloyd D; Rose, Laura; Schaefer, Frank W; Noble-Wang, Judith; Hodges, Lisa; Lindquist, H D Alan; Deye, Gregory J; Arduino, Matthew J

    2009-07-01

    After the 2001 anthrax incidents, surface sampling techniques for biological agents were found to be inadequately validated, especially at low surface loadings. We aerosolized Bacillus anthracis Sterne spores within a chamber to achieve very low surface loading (ca. 3, 30, and 200 CFU per 100 cm(2)). Steel and carpet coupons seeded in the chamber were sampled with swab (103 cm(2)) or wipe or vacuum (929 cm(2)) surface sampling methods and analyzed at three laboratories. Agar settle plates (60 cm(2)) were the reference for determining recovery efficiency (RE). The minimum estimated surface concentrations to achieve a 95% response rate based on probit regression were 190, 15, and 44 CFU/100 cm(2) for sampling steel surfaces and 40, 9.2, and 28 CFU/100 cm(2) for sampling carpet surfaces with swab, wipe, and vacuum methods, respectively; however, these results should be cautiously interpreted because of high observed variability. Mean REs at the highest surface loading were 5.0%, 18%, and 3.7% on steel and 12%, 23%, and 4.7% on carpet for the swab, wipe, and vacuum methods, respectively. Precision (coefficient of variation) was poor at the lower surface concentrations but improved with increasing surface concentration. The best precision was obtained with wipe samples on carpet, achieving 38% at the highest surface concentration. The wipe sampling method detected B. anthracis at lower estimated surface concentrations and had higher RE and better precision than the other methods. These results may guide investigators to more meaningfully conduct environmental sampling, quantify contamination levels, and conduct risk assessment for humans.

  4. Recovery Efficiency and Limit of Detection of Aerosolized Bacillus anthracis Sterne from Environmental Surface Samples ▿

    Science.gov (United States)

    Estill, Cheryl Fairfield; Baron, Paul A.; Beard, Jeremy K.; Hein, Misty J.; Larsen, Lloyd D.; Rose, Laura; Schaefer, Frank W.; Noble-Wang, Judith; Hodges, Lisa; Lindquist, H. D. Alan; Deye, Gregory J.; Arduino, Matthew J.

    2009-01-01

    After the 2001 anthrax incidents, surface sampling techniques for biological agents were found to be inadequately validated, especially at low surface loadings. We aerosolized Bacillus anthracis Sterne spores within a chamber to achieve very low surface loading (ca. 3, 30, and 200 CFU per 100 cm2). Steel and carpet coupons seeded in the chamber were sampled with swab (103 cm2) or wipe or vacuum (929 cm2) surface sampling methods and analyzed at three laboratories. Agar settle plates (60 cm2) were the reference for determining recovery efficiency (RE). The minimum estimated surface concentrations to achieve a 95% response rate based on probit regression were 190, 15, and 44 CFU/100 cm2 for sampling steel surfaces and 40, 9.2, and 28 CFU/100 cm2 for sampling carpet surfaces with swab, wipe, and vacuum methods, respectively; however, these results should be cautiously interpreted because of high observed variability. Mean REs at the highest surface loading were 5.0%, 18%, and 3.7% on steel and 12%, 23%, and 4.7% on carpet for the swab, wipe, and vacuum methods, respectively. Precision (coefficient of variation) was poor at the lower surface concentrations but improved with increasing surface concentration. The best precision was obtained with wipe samples on carpet, achieving 38% at the highest surface concentration. The wipe sampling method detected B. anthracis at lower estimated surface concentrations and had higher RE and better precision than the other methods. These results may guide investigators to more meaningfully conduct environmental sampling, quantify contamination levels, and conduct risk assessment for humans. PMID:19429546

  5. Role of sea surface temperature responses in simulation of the climatic effect of mineral dust aerosol

    Directory of Open Access Journals (Sweden)

    X. Yue

    2011-06-01

    Full Text Available Mineral dust aerosol can be transported over the nearby oceans and influence the energy balance at the sea surface. The role of dust-induced sea surface temperature (SST responses in simulations of the climatic effect of dust is examined by using a general circulation model with online simulation of mineral dust and a coupled mixed-layer ocean model. Both the longwave and shortwave radiative effects of mineral dust aerosol are considered in climate simulations. The SST responses are found to be very influential on simulated dust-induced climate change, especially when climate simulations consider the two-way dust-climate coupling to account for the feedbacks. With prescribed SSTs and dust concentrations, we obtain an increase of 0.02 K in the global and annual mean surface air temperature (SAT in response to dust radiative effects. In contrast, when SSTs are allowed to respond to radiative forcing of dust in the presence of the dust cycle-climate interactions, we obtain a global and annual mean cooling of 0.09 K in SAT by dust. The extra cooling simulated with the SST responses can be attributed to the following two factors: (1 The negative net (shortwave plus longwave radiative forcing of dust at the surface reduces SST, which decreases latent heat fluxes and upward transport of water vapor, resulting in less warming in the atmosphere; (2 The positive feedback between SST responses and dust cycle. The dust-induced reductions in SST lead to reductions in precipitation (or wet deposition of dust and hence increase the global burden of small dust particles. These small particles have strong scattering effects, which enhance the dust cooling at the surface and further reduce SSTs.

  6. Aerosol and monsoon climate interactions over Asia: AEROSOL AND MONSOON CLIMATE INTERACTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhanqing [State Key Laboratory of Earth Surface Processes and Resource Ecology and College of Global Change and Earth System Science, Beijing Normal University, Beijing China; Department of Atmospheric and Oceanic Science and ESSIC, University of Maryland, College Park Maryland USA; Lau, W. K. -M. [Department of Atmospheric and Oceanic Science and ESSIC, University of Maryland, College Park Maryland USA; Ramanathan, V. [Department of Atmospheric and Climate Sciences, University of California, San Diego California USA; Wu, G. [Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing China; Ding, Y. [National Climate Center, China Meteorological Administration, Beijing China; Manoj, M. G. [Department of Atmospheric and Oceanic Science and ESSIC, University of Maryland, College Park Maryland USA; Liu, J. [Department of Atmospheric and Oceanic Science and ESSIC, University of Maryland, College Park Maryland USA; Qian, Y. [Pacific Northwest National Laboratory, Richland Washington USA; Li, J. [State Key Laboratory of Earth Surface Processes and Resource Ecology and College of Global Change and Earth System Science, Beijing Normal University, Beijing China; Zhou, T. [Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing China; Fan, J. [Pacific Northwest National Laboratory, Richland Washington USA; Rosenfeld, D. [Institute of Earth Sciences, Hebrew University, Jerusalem Israel; Ming, Y. [Geophysical Fluid Dynamic Laboratory, NOAA, Princeton New Jersey USA; Wang, Y. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena California USA; Huang, J. [College of Atmospheric Sciences, Lanzhou University, Lanzhou China; Wang, B. [Department of Atmospheric Sciences, University of Hawaii, Honolulu Hawaii USA; School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing China; Xu, X. [Chinese Academy of Meteorological Sciences, Beijing China; Lee, S. -S. [Department of Atmospheric and Oceanic Science and ESSIC, University of Maryland, College Park Maryland USA; Cribb, M. [Department of Atmospheric and Oceanic Science and ESSIC, University of Maryland, College Park Maryland USA; Zhang, F. [State Key Laboratory of Earth Surface Processes and Resource Ecology and College of Global Change and Earth System Science, Beijing Normal University, Beijing China; Yang, X. [State Key Laboratory of Earth Surface Processes and Resource Ecology and College of Global Change and Earth System Science, Beijing Normal University, Beijing China; Zhao, C. [State Key Laboratory of Earth Surface Processes and Resource Ecology and College of Global Change and Earth System Science, Beijing Normal University, Beijing China; Takemura, T. [Research Institute for Applied Mechanics, Kyushu University, Fukuoka Japan; Wang, K. [State Key Laboratory of Earth Surface Processes and Resource Ecology and College of Global Change and Earth System Science, Beijing Normal University, Beijing China; Xia, X. [Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing China; Yin, Y. [School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing China; Zhang, H. [National Climate Center, China Meteorological Administration, Beijing China; Guo, J. [Chinese Academy of Meteorological Sciences, Beijing China; Zhai, P. M. [Chinese Academy of Meteorological Sciences, Beijing China; Sugimoto, N. [National Institute for Environmental Studies, Tsukuba Japan; Babu, S. S. [Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram India; Brasseur, G. P. [Max Planck Institute for Meteorology, Hamburg Germany

    2016-11-15

    Asian monsoons and aerosols have been studied extensively which are intertwined in influencing the climate of Asia. This paper provides a comprehensive review of ample studies on Asian aerosol, monsoon and their interactions. The region is the primary source of aerosol emissions of varies species, influenced by distinct weather and climatic regimes. On continental scale, aerosols reduce surface insolation and weaken the land-ocean thermal contrast, thus inhibiting the development of monsoons. Locally, aerosol radiative effects alter the thermodynamic stability and convective potential of the lower atmosphere leading to reduced temperatures, increased atmospheric stability, and weakened wind and atmospheric circulation. The atmospheric thermodynamic state may also be altered by the aerosol serving as cloud condensation nuclei or ice nuclei. Many mechanisms have been put forth regarding how aerosols modulate the amplitude, frequency, intensity, and phase of numerous monsoon climate variables. A wide range of theoretical, observational, and modeling findings on the Asian monsoon, aerosols, and their interactions are synthesized. A new paradigm is proposed on investigating aerosol-monsoon interactions, in which natural aerosols such as desert dust, black carbon from biomass burning, and biogenic aerosols from vegetation are considered integral components of an intrinsic aerosol-monsoon climate system, subject to external forcings of global warming, anthropogenic aerosols, and land use and change. Future research on aerosol-monsoon interactions calls for an integrated approach and international collaborations based on long-term sustained observations, process measurements, and improved models, as well as using observations to constrain model simulations and projections.

  7. Asian industrial lead inputs to the North Pacific evidenced by lead concentrations and isotopic compositions in surface waters and aerosols.

    Science.gov (United States)

    Gallon, Céline; Ranville, Mara A; Conaway, Christopher H; Landing, William M; Buck, Clifton S; Morton, Peter L; Flegal, A Russell

    2011-12-01

    Recent trends of atmospheric lead deposition to the North Pacific were investigated with analyses of lead in aerosols and surface waters collected on the fourth Intergovernmental Oceanographic Commission Contaminant Baseline Survey from May to June, 2002. Lead concentrations of the aerosols varied by 2 orders of magnitude (0.1-26.4 pmol/m(3)) due in part to variations in dust deposition during the cruise. The ranges in lead aerosol enrichment factors relative to iron (1-119) and aluminum (3-168) were similar, evidencing the transport of Asian industrial lead aerosols across the North Pacific. The oceanic deposition of some of those aerosols was substantiated by the gradient of lead concentrations of North Pacific waters, which varied 3-fold (32.7-103.5 pmol/kg), were highest along with the Asian margin of the basin, and decreased eastward. The hypothesized predominance of Asian industrial lead inputs to the North Pacific was further corroborated by the lead isotopic composition of ocean surface waters ((206)Pb/(207)Pb = 1.157-1.169; (208)Pb/(206)Pb = 2.093-2.118), which fell within the range of isotopic ratios reported in Asian aerosols that are primarily attributed to Chinese industrial lead emissions.

  8. On the effect of different aerosol types on surface solar radiation levels over the region of Eastern Mediterranean

    Science.gov (United States)

    Alexandri, Georgia; Georgoulias, Aristeidis K.; Kourtidis, Konstantinos; Meleti, Charikleia; Balis, Dimitris

    2014-05-01

    In this work, we examine the direct effect of different aerosol types on the surface solar radiation (SSR) levels in the region of Eastern Mediterranean. Simulations with the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model were performed using ground and satellite-based data as input. An IDL tool that "feeds" SBDART with the appropriate input data was developed allowing us to simulate SSR with a time step of 1 hour. Level-2 aerosol optical depth, cloud optical depth, cloud fraction, effective droplet radius, cloud top pressure, precipitable water and surface albedo data from MODIS, as well as ozone total column data from Earth Probe TOMS and OMI satellite sensors, coarse resolution cloud data from the ISCCP and single scattering albedo, asymmetry factor and Angström exponent sunphotometric data from the AERONET are used in our radiative transfer simulations. Simulations are performed over selected spots within Eastern Mediterranean for clear, liquid cloud and ice cloud covered skies and for different aerosol types (maritime, dust, anthropogenic, fine-mode natural). The optical properties of aerosols were determined using a combination of satellite, ground-based, model and reanalysis products. The aerosol direct radiative effect is defined as the difference between simulations done with and without the presence of aerosols. This research has been financed by EPAN II and PEP under the national action "Bilateral, multilateral and regional R&T cooperations" (AEROVIS Sino-Greek project).

  9. Backscatter measurements of aerosolized CB simulants with a frequency agile CO2 lidar

    Science.gov (United States)

    Vanderbeek, Richard; Gurton, Kristan

    2004-02-01

    A novel windowless chamber was developed to allow aerosol backscatter measurements with a frequency-agile CO2 lidar. The chamber utilizes curtains of air to contain the cloud, thus preventing the inevitable backscatter off of conventional windows from corrupting the desired measurements. This feature is critical because the CO2 lidar has a long (1 μs) pulse and the backscatter off the window cannot be temporally separated from the backscatter off the aerosol in the chamber. The chamber was designed for testing with a variety of CB simulants and interferents in both vapor and aerosol form and has been successfully shown to contain a cloud of known size, concentration, and particle size distribution for 10-15 minutes. This paper shows the results using Arizona road dust that was screened by the manufacturer into 0-3 μm and 5-10 μm particle size distributions. The measurements clearly show the effect of size distribution on the infrared backscatter coefficients as well as the dynamic nature of the size distribution for a population of aerosols. The test methodology and experimental results are presented.

  10. Ozone, spectral irradiance and aerosol measurements with the Brewer spectro radiometer

    International Nuclear Information System (INIS)

    Marenco, F.; Di Sarra, A.

    2001-01-01

    In this technical report a detailed description of the Brewer spectro radiometer, a widespread instrument for ozone and ultraviolet radiation, is given. The methodologies used to measure these quantities and for instrument calibration are described in detail. Finally a new methodology, developed by ENEA to derive the aerosol optical depth from the Brewer routine total ozone measurements, is described. This methodology is based on Langley extrapolation, on the determination of the transmissivity of the Brewer neutral density filters, and on a statistically significant number of half days of measurements obtained in could-free conditions. Results of this method, obtained with the Brewer of the ENEA station for climate observations Roberto Sarao, located in the island of Lampedusa, are reported. These results confirm the validity of the method, thanks to independent measurements taken in 1999 with a Multi filter Rotating Shadow band Radiometer. This methodology allows researchers to obtain an aerosol climatology from ozone measurements obtained at several sites world-wide [it

  11. Quantitative measurement of aerosol deposition on skin, hair and clothing for dosimetric assessment. Final report

    International Nuclear Information System (INIS)

    Fogh, C.L.; Byrne, M.A.; Andersson, K.G.; Bell, K.F.; Roed, J.; Goddard, A.J.H.; Vollmair, D.V.; Hotchkiss, S.A.M.

    1999-06-01

    In the past, very little thought has been given to the processes and implications of deposition of potentially hazardous aerosol directly onto humans. This state of unpreparedness is unsatisfactory and suitable protocols have been developed and validated for tracer experiments to investigate the deposition and subsequent fate of contaminant aerosol on skin, hair and clothing. The main technique applied involves the release and subsequent deposition on volunteers in test rooms of particles of different sizes labelled with neutron activatable rare earth tracers. Experiments indicate that the deposition velocity to skin increases linearly with the particle size. A wind tunnel experiment simulating outdoor conditions showed a dependence on skin deposition velocity of wind speed, indicating that outdoor deposition velocities may be great. Both in vivo and in vitro experiments were conducted, and the influence of various factors, such as surface type, air flow, heating and electrostatics were examined. The dynamics of particle removal from human skin were studied by fluorescence scanning. This technique was also applied to estimate the fraction of aerosol dust transferred to skin by contact with a contaminated surface. The various parameters determined were applied to establish a model for calculation of radiation doses received from deposition of airborne radioactive aerosol on human body surfaces. It was found that the gamma doses from deposition on skin may be expected to be of the same order of magnitude as the gamma doses received over the first year from contamination on outdoor surfaces. According to the calculations, beta doses from skin deposition to individuals in areas of Russia, where dry deposition of Chernobyl fallout led to very high levels of contamination, may have amounted to several Sievert and may thus be responsible for a significant cancer risk. (au)

  12. First measurements and model calculations on the adsorption of radioactive nuclides to Aitken nucleus aerosols

    International Nuclear Information System (INIS)

    Fritz, G.

    From the viewpoint of disaster relief the knowledge of the adsorption coefficient as a function of aerosol size is important. Its theoretical assessment is only possible by completing diffusion theory with Fuchs' theory of limited spheres. To carry out the adsorption experiments SO 4 particles were produced which, because of their high concentration, coagulated further to particles of the size 10 -6 to 10 -5 . Proportionality to the surface of the particles is found. (DG) [de

  13. Measurements of Primary Biogenic Aerosol Particles with an Ultraviolet Aerodynamic Particle Sizer (UVAPS) During AMAZE-08

    Science.gov (United States)

    Wollny, A. G.; Garland, R.; Pöschl, U.

    2008-12-01

    Biogenic aerosols are ubiquitous in the Earth's atmosphere and they influence atmospheric chemistry and physics, the biosphere, climate, and public health. They play an important role in the spread of biological organisms and reproductive materials, and they can cause or enhance human, animal, and plant diseases. Moreover, they influence the Earth's energy budget by scattering and absorbing radiation, and they can initiate the formation of clouds and precipitation as cloud condensation and ice nuclei. The composition, abundance, and origin of biogenic aerosol particles and components are, however, still not well understood and poorly quantified. Prominent examples of primary biogenic aerosol particles, which are directly emitted from the biosphere to the atmosphere, are pollen, bacteria, fungal spores, viruses, and fragments of animals and plants. During the AMazonian Aerosol CharacteriZation Experiment (AMAZE-08) a large number of aerosol and gas-phase measurements were taken on a remote site close to Manaus, Brazil, during a period of five weeks in February and March 2008. The presented study is focused on data from an ultraviolet aerodynamic particle sizer (UVAPS, TSI inc.) that has been deployed for the first time in Amazonia. In this instrument, particle counting and aerodynamic sizing over the range of 0.5-20 μm are complemented by the measurement of UV fluorescence at 355 nm (excitation) and 420-575 nm (emission), respectively. Fluorescence at these wavelengths is characteristic for reduced pyridine nucleotides (e.g., NAD(P)H) and for riboflavin, which are specific for living cells. Thus particles exhibiting fluorescence signals can be regarded as 'viable aerosols' or 'fluorescent bioparticles' (FBAP), and their concentration can be considered as lower limit for the actual abundance of primary biogenic aerosol particles. First data analyses show a pronounced peak of FBAP at diameters around 2-3 μm. In this size range the biogenic particle fraction was

  14. Target categorization of aerosol and clouds by continuous multiwavelength-polarization lidar measurements

    Science.gov (United States)

    Baars, Holger; Seifert, Patric; Engelmann, Ronny; Wandinger, Ulla

    2017-09-01

    Absolute calibrated signals at 532 and 1064 nm and the depolarization ratio from a multiwavelength lidar are used to categorize primary aerosol but also clouds in high temporal and spatial resolution. Automatically derived particle backscatter coefficient profiles in low temporal resolution (30 min) are applied to calibrate the lidar signals. From these calibrated lidar signals, new atmospheric parameters in temporally high resolution (quasi-particle-backscatter coefficients) are derived. By using thresholds obtained from multiyear, multisite EARLINET (European Aerosol Research Lidar Network) measurements, four aerosol classes (small; large, spherical; large, non-spherical; mixed, partly non-spherical) and several cloud classes (liquid, ice) are defined. Thus, particles are classified by their physical features (shape and size) instead of by source. The methodology is applied to 2 months of continuous observations (24 h a day, 7 days a week) with the multiwavelength-Raman-polarization lidar PollyXT during the High-Definition Clouds and Precipitation for advancing Climate Prediction (HD(CP)2) Observational Prototype Experiment (HOPE) in spring 2013. Cloudnet equipment was operated continuously directly next to the lidar and is used for comparison. By discussing three 24 h case studies, it is shown that the aerosol discrimination is very feasible and informative and gives a good complement to the Cloudnet target categorization. Performing the categorization for the 2-month data set of the entire HOPE campaign, almost 1 million pixel (5 min × 30 m) could be analysed with the newly developed tool. We find that the majority of the aerosol trapped in the planetary boundary layer (PBL) was composed of small particles as expected for a heavily populated and industrialized area. Large, spherical aerosol was observed mostly at the top of the PBL and close to the identified cloud bases, indicating the importance of hygroscopic growth of the particles at high relative

  15. Retrieval of desert dust aerosol vertical profiles from IASI measurements in the TIR atmospheric window

    Directory of Open Access Journals (Sweden)

    S. Vandenbussche

    2013-10-01

    Full Text Available Desert dust aerosols are the most prominent tropospheric aerosols, playing an important role in the earth's climate. However, their radiative forcing is currently not known with sufficient precision to even determine its sign. The sources of uncertainty are multiple, one of them being a poor characterisation of the dust aerosol's vertical profile on a global scale. In this work, we tackle this scientific issue by designing a method for retrieving dust aerosol vertical profiles from Thermal Infrared measurements by Infrared Atmospheric Sounding Interferometer (IASI instruments onboard the Metop satellite series. IASI offers almost global coverage twice a day, and long (past and future time series of radiances, therefore being extremely well suited for climate studies. Our retrieval follows Rodger's formalism and is based on a two-step approach, treating separately the issues of low altitude sensitivity and difficult a priori definition. We compare our results for a selected test case above the Atlantic Ocean and North Africa in June 2009, with optical depth data from MODIS, aerosol absorbing index from GOME-2 and OMI, and vertical profiles of extinction coefficients from CALIOP. We also use literature information on desert dust sources to interpret our results above land. Our retrievals provide perfectly reasonable results in terms of optical depth. The retrieved vertical profiles (with on average 1.5 degrees of freedom show most of the time sensitivity down to the lowest layer, and agree well with CALIOP extinction profiles for medium to high dust optical depth. We conclude that this new method is extremely promising for improving the scientific knowledge about the 3-D distribution of desert dust aerosols in the atmosphere.

  16. Measurement of contemporary and fossil carbon contents of PM 2.5 aerosols: results from Turtleback Dome, Yosemite National Park

    International Nuclear Information System (INIS)

    Bench, G

    2003-01-01

    The impact of aerosol particulate matter of mean mass aerodynamic diameter (le) 2.5 ∝m (PM 2.5 aerosols), on health, visibility, and compliance with EPA's regional haze regulations is a growing concern. Techniques that can help better characterize particulate matter are required to better understand the constituents, causes and sources of PM 2.5 aerosols. Measurement of the 14 C/C ratio of the PM 2.5 aerosols, the absence of 14 C in fossil carbon materials and the known 14 C/C levels in contemporary carbon materials allows use of a two-component model to derive contemporary and fossil carbon contents of the particulate matter. Such data can be used to estimate the relative contributions of fossil fuels and biogenic aerosols to the total aerosol loading. Here, the methodology for performing such an assessment using total suspended particulate Hi-vol aerosol samplers to collect PM 2.5 aerosols on quartz fiber filters and the technique of accelerator mass spectrometry to measure 14 C/C ratios is presented and illustrated using PM 2.5 aerosols collected at Yosemite National Park

  17. Modeling and evaluation of the global sea-salt aerosol distribution: sensitivity to size-resolved and sea-surface temperature dependent emission schemes

    Directory of Open Access Journals (Sweden)

    M. Spada

    2013-12-01

    Full Text Available One of the major sources of uncertainty in model estimates of the global sea-salt aerosol distribution is the emission parameterization. We evaluate a new sea-salt aerosol life cycle module coupled to the online multiscale chemical transport model NMMB/BSC-CTM. We compare 5 yr global simulations using five state-of-the-art sea-salt open-ocean emission schemes with monthly averaged coarse aerosol optical depth (AOD from selected AERONET sun photometers, surface concentration measurements from the University of Miami's Ocean Aerosol Network, and measurements from two NOAA/PMEL cruises (AEROINDOEX and ACE1. Model results are highly sensitive to the introduction of sea-surface-temperature (SST-dependent emissions and to the accounting of spume particles production. Emission ranges from 3888 Tg yr−1 to 8114 Tg yr−1, lifetime varies between 7.3 h and 11.3 h, and the average column mass load is between 5.0 Tg and 7.2 Tg. Coarse AOD is reproduced with an overall correlation of around 0.5 and with normalized biases ranging from +8.8% to +38.8%. Surface concentration is simulated with normalized biases ranging from −9.5% to +28% and the overall correlation is around 0.5. Our results indicate that SST-dependent emission schemes improve the overall model performance in reproducing surface concentrations. On the other hand, they lead to an overestimation of the coarse AOD at tropical latitudes, although it may be affected by uncertainties in the comparison due to the use of all-sky model AOD, the treatment of water uptake, deposition and optical properties in the model and/or an inaccurate size distribution at emission.

  18. Measuring Surface Combatant Fleet Effectiveness

    National Research Council Canada - National Science Library

    Crary, Michael

    1999-01-01

    ...? While Measures of Effectiveness for an individual ship can include its number of missiles, speed, and endurance, it is difficult to find a Measure of Effectiveness credible to experienced warplanners...

  19. Measurements of aerosol particles in the Škocjan Caves, Slovenia.

    Science.gov (United States)

    Grgić, Irena; Iskra, Ivan; Podkrajšek, Boštjan; Gerjevič, Vanja Debevec

    2014-02-01

    For the first time, continuous aerosol measurements were performed in the Škocjan Caves, one of the most important cave systems in the world, and listed by UNESCO as a natural and cultural world heritage site since 1986. Measurements of PM10 were performed during three different periods: (1) in December 2011, the average background concentration was found to be about 4 μg m(-3); (2) in June 2012, a higher concentration was measured (8 μg m(-3)); and (3) from 8 to 20 August 2012, the highest concentration of 15.3 μg m(-3) was measured. Based on the PM10 measurement results, and as compared to similar measurements outside the cave, it can be hypothesized that the increase in the cave's aerosol concentration during the summer was connected to both the higher number of visitors and the polluted atmospheric air entering the cave upon entering of the cave system. Additional measurement of nanoparticles with scanning mobility particle sizer spectrometer (size between 14.1 and 710.5 nm) confirmed these findings; during the summer period, a severe raise in the total aerosol concentration of 30-50 times was found when groups of visitors entered the cave. Our results on nanoparticles demonstrated that we were able to detect very small changes and variations in aerosol concentration inside the cave. To our knowledge, these are the first results on nanoaerosol measurements in a cave, and we believe that such measurements may lead to the implementation of better protection of delicate cave systems.

  20. Inferring brown carbon content from UV aerosol absorption measurements during biomass burning season

    Science.gov (United States)

    Mok, J.; Krotkov, N. A.; Arola, A. T.; Torres, O.; Jethva, H. T.; Andrade, M.; Labow, G. J.; Eck, T. F.; Li, Z.; Dickerson, R. R.; Stenchikov, G. L.; Osipov, S.

    2015-12-01

    Measuring spectral dependence of light absorption by colored organic or "brown" carbon (BrC) is important, because of its effects on photolysis rates of ozone and surface ultraviolet (UV) radiation. Enhanced UV spectral absorption by BrC can in turn be exploited for simultaneous retrievals of BrC and black carbon (BC) column amounts in field campaigns. We present an innovative ground-based retrieval of BC and BrC volume fractions and their mass absorption efficiencies during the biomass burning season in Santa Cruz, Bolivia in September-October 2007. Our method combines retrieval of BC volume fraction using AERONET inversion in visible wavelengths with the inversion of total BC+BrC absorption (i.e., column effective imaginary refractive index, kmeas) using Diffuse/Direct irradiance measurements in UV wavelengths. First, we retrieve BrC volume fraction by fitting kmeas at 368nm using Maxwell-Garnett (MG) mixing rules assuming: (1) flat spectral dependence of kBC, (2) known value of kBrC at 368nm from laboratory absorption measurements or smoke chamber experiments, and (3) known BC volume fraction from AERONET inversion. Next, we derive kBrC in short UVB wavelengths by fitting kmeas at 305nm, 311nm, 317nm, 325nm, and 332nm using MG mixing rules and fixed volume fractions of BC and BrC. Our retrievals show larger than expected spectral dependence of kBrC in UVB wavelengths, implying reduced surface UVB irradiance and inhibited photolysis rates of surface ozone destruction. We use a one-dimensional chemical box model to show that the observed strong wavelength dependence of BrC absorption leads to inhibited photolysis of ozone to O(1D), a loss mechanism, while having little impact or even accelerating photolysis of NO2, an ozone production mechanism. Although BC only absorption in biomass burning aerosols is important for climate radiative forcing in the visible wavelengths, additional absorption by BrC is important because of its impact on surface UVB radiation

  1. Volatility measurement of atmospheric submicron aerosols in an urban atmosphere in southern China

    Directory of Open Access Journals (Sweden)

    L.-M. Cao

    2018-02-01

    Full Text Available Aerosol pollution has been a very serious environmental problem in China for many years. The volatility of aerosols can affect the distribution of compounds in the gas and aerosol phases, the atmospheric fates of the corresponding components, and the measurement of the concentration of aerosols. Compared to the characterization of chemical composition, few studies have focused on the volatility of aerosols in China. In this study, a thermodenuder aerosol mass spectrometer (TD-AMS system was deployed to study the volatility of non-refractory submicron particulate matter (PM1 species during winter in Shenzhen. To our knowledge, this paper is the first report of the volatilities of aerosol chemical components based on a TD-AMS system in China. The average PM1 mass concentration during the experiment was 42.7±20.1 µg m−3, with organic aerosol (OA being the most abundant component (43.2 % of the total mass. The volatility of chemical species measured by the AMS varied, with nitrate showing the highest volatility, with a mass fraction remaining (MFR of 0.57 at 50 °C. Organics showed semi-volatile characteristics (the MFR was 0.88 at 50 °C, and the volatility had a relatively linear correlation with the TD temperature (from the ambient temperature to 200 °C, with an evaporation rate of 0.45 % °C−1. Five subtypes of OA were resolved from total OA using positive matrix factorization (PMF for data obtained under both ambient temperature and high temperatures through the TD, including a hydrocarbon-like OA (HOA, accounting for 13.5 %, a cooking OA (COA, 20.6 %, a biomass-burning OA (BBOA, 8.9 %, and two oxygenated OAs (OOAs: a less-oxidized OOA (LO-OOA, 39.1 % and a more-oxidized OOA (MO-OOA, 17.9 %. Different OA factors presented different volatilities, and the volatility sequence of the OA factors at 50 °C was HOA (MFR of 0.56  >  LO-OOA (0.70  >  COA (0.85  ≈  BBOA (0.87

  2. DRAGON-West Japan campaign in 2012: regional aerosol measurements over Osaka

    Science.gov (United States)

    Sano, I.; Mukai, S.; Holben, B. N.; Nakata, M.; Yonemitsu, M.; Sugimoto, N.; Fujito, T.; Hiraki, T.; Iguchi, N.; Kozai, K.; Kuji, M.; Muramatsu, K.; Okada, Y.; Okada, Y.; Sadanaga, Y.; Tohno, S.; Toyazaki, Yasuo; Yamamoto, Kouhei

    2012-11-01

    It is known that the aerosol distribution in Asia is complicated due to the increasing emissions of anthropogenic aerosols in association with economic growth and natural dust significantly varied with the seasons. Therefore it is clear that local spatially and temporally resolved measurements of atmospheric aerosols in Asian urban city are necessary. Since Osaka, Kobe, Kyoto, and Nara are located in very close each others (all cities are included in around 70×70 km2 area). The population of the region is around 13 millions including neighbor prefectures, accordingly air quality in this region is slightly bad in comparison with the remote area. Furthermore, in recent years, Asian dusts and anthropogenic small particles some times transported from China and cover these cities throughout year. DRAGON (Distributed Regional Aerosol Gridded Observation Network) is a project of dense sun/sky radiometer network in the urban area. The DRAGON-West Japan field campaign was performed over Osaka and neighbor cities with 7 AERONET instruments from March to end of May in 2012. As results, DRAGON measurements indicate small differences among the values of AOT over Osaka region.

  3. Towards routine measurements of meteorological and aerosol parameters using small unmanned aerial and tethered balloon systems

    Science.gov (United States)

    Mei, F.; Dexheimer, D.; Hubbe, J. M.; deBoer, G.; Schmid, B.; Ivey, M.; Longbottom, C.; Carroll, P.

    2017-12-01

    The Inaugural Campaigns for ARM Research using Unmanned Systems (ICARUS) had been launched in 2016 and then the effort has been continued in 2017. ICARUS centered on Oliktok Point, Alaska focusses on developing routine operations of Unmanned Aerial Systems (UAS) and Tethered Balloon Systems (TBS). The operation routine practiced during ICARUS 2016 provided valuable guidance for the ICARUS 2017 deployment. During two intensive operation periods in 2017, a small DataHawk II UAS has been deployed to collect data for two weeks each in May and August. Coordinated with DataHawk flights, the TBS has been launched with meteorology sensors such as iMet and Tethersondes, therefore vertical profiles of the basic atmospheric state (temperature, humidity, and horizontal wind) were observed simultaneously by UAS and TBS. In addition, an aerosol payload was attached and launched with 2 TBS flights in April and 7 TBS flights in May, which include a condensation particle counter (CPC, TSI 3007) and two printed optical particle spectrometers (POPS, Handix TBS version). The two POPS were operated at different inlet temperatures. This approach provided potential measurements for aerosol optical closure in future. Measured aerosol properties include total particle number concentrations, particle size distribution, at different ambient temperature and relative humidity. Vertical profiles of atmospheric state and aerosol properties will be discussed based on the coordinated flights. Monthly variation will be assessed with data from the upcoming August flights.

  4. Measurement of an electronic cigarette aerosol size distribution during a puff

    Directory of Open Access Journals (Sweden)

    Belka Miloslav

    2017-01-01

    Full Text Available Electronic cigarettes (e-cigarettes have become very popular recently because they are marketed as a healthier alternative to tobacco smoking and as a useful tool to smoking cessation. E-cigarettes use a heating element to create an aerosol from a solution usually consisting of propylene glycol, glycerol, and nicotine. Despite the wide spread of e-cigarettes, information about aerosol size distributions is rather sparse. This can be caused by the relative newness of e-cigarettes and by the difficulty of the measurements, in which one has to deal with high concentration aerosol containing volatile compounds. Therefore, we assembled an experimental setup for size measurements of e-cigarette aerosol in conjunction with a piston based machine in order to simulate a typical puff. A TSI scanning mobility particle sizer 3936 was employed to provide information about particle concentrations and sizes. An e-cigarette commercially available on the Czech Republic market was tested and the results were compared with a conventional tobacco cigarette. The particles emitted from the e-cigarette were smaller than those of the conventional cigarette having a CMD of 150 and 200 nm. However, the total concentration of particles from e-cigarette was higher.

  5. Measurement of an electronic cigarette aerosol size distribution during a puff

    Science.gov (United States)

    Belka, Miloslav; Lizal, Frantisek; Jedelsky, Jan; Jicha, Miroslav; Pospisil, Jiri

    Electronic cigarettes (e-cigarettes) have become very popular recently because they are marketed as a healthier alternative to tobacco smoking and as a useful tool to smoking cessation. E-cigarettes use a heating element to create an aerosol from a solution usually consisting of propylene glycol, glycerol, and nicotine. Despite the wide spread of e-cigarettes, information about aerosol size distributions is rather sparse. This can be caused by the relative newness of e-cigarettes and by the difficulty of the measurements, in which one has to deal with high concentration aerosol containing volatile compounds. Therefore, we assembled an experimental setup for size measurements of e-cigarette aerosol in conjunction with a piston based machine in order to simulate a typical puff. A TSI scanning mobility particle sizer 3936 was employed to provide information about particle concentrations and sizes. An e-cigarette commercially available on the Czech Republic market was tested and the results were compared with a conventional tobacco cigarette. The particles emitted from the e-cigarette were smaller than those of the conventional cigarette having a CMD of 150 and 200 nm. However, the total concentration of particles from e-cigarette was higher.

  6. A review of optical measurements at the aerosol and cloud chamber AIDA

    International Nuclear Information System (INIS)

    Wagner, Robert; Linke, Claudia; Naumann, Karl-Heinz; Schnaiter, Martin; Vragel, Marlen; Gangl, Martin; Horvath, Helmuth

    2009-01-01

    This paper provides a survey of recent studies on the optical properties of aerosol and cloud particles that have been conducted at the AIDA facility of Forschungszentrum Karlsruhe (Aerosol Interactions and Dynamics in the Atmosphere). Reflecting the broad accessible temperature range of the AIDA chamber which extends from ambient temperature down to 183 K, the investigations feature a broad diversity of research topics, such as the wavelength-dependence of the specific absorption cross sections of soot and mineral dust aerosols at room temperature, depolarization and infrared extinction measurements of ice crystal clouds generated at temperatures below 235 K, and the optical properties of polar stratospheric cloud constituents whose formation was studied in chamber experiments at temperatures well below 200 K. After reviewing the AIDA research activity of the past decade and introducing the optical instrumentation of the AIDA facility, this paper presents illustrative examples of ongoing and already published work on optical measurements of soot aerosols, mineral dust particles, and ice crystal clouds.

  7. Complex chemical composition of colored surface films formed from reactions of propanal in sulfuric acid at upper troposphere/lower stratosphere aerosol acidities.

    Science.gov (United States)

    Van Wyngarden, A L; Pérez-Montaño, S; Bui, J V H; Li, E S W; Nelson, T E; Ha, K T; Leong, L; Iraci, L T

    Particles in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40-80 wt %) in water. However, airborne measurements have shown that these particles also contain a significant fraction of organic compounds of unknown chemical composition. Acid-catalyzed reactions of carbonyl species are believed to be responsible for significant transfer of gas phase organic species into tropospheric aerosols and are potentially more important at the high acidities characteristic of UT/LS particles. In this study, experiments combining sulfuric acid (H 2 SO 4 ) with propanal and with mixtures of propanal with glyoxal and/or methylglyoxal at acidities typical of UT/LS aerosols produced highly colored surface films (and solutions) that may have implications for aerosol properties. In order to identify the chemical processes responsible for the formation of the surface films, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and 1 H nuclear magnetic resonance (NMR) spectroscopies were used to analyze the chemical composition of the films. Films formed from propanal were a complex mixture of aldol condensation products, acetals and propanal itself. The major aldol condensation products were the dimer (2-methyl-2-pentenal) and 1,3,5-trimethylbenzene that was formed by cyclization of the linear aldol condensation trimer. Additionally, the strong visible absorption of the films indicates that higher-order aldol condensation products must also be present as minor species. The major acetal species were 2,4,6-triethyl-1,3,5-trioxane and longer-chain linear polyacetals which are likely to separate from the aqueous phase. Films formed on mixtures of propanal with glyoxal and/or methylglyoxal also showed evidence of products of cross-reactions. Since cross-reactions would be more likely than self-reactions under atmospheric conditions, similar reactions of aldehydes like propanal with common aerosol organic species like glyoxal

  8. Complex chemical composition of colored surface films formed from reactions of propanal in sulfuric acid at upper troposphere/lower stratosphere aerosol acidities

    Science.gov (United States)

    Van Wyngarden, A. L.; Pérez-Montaño, S.; Bui, J. V. H.; Li, E. S. W.; Nelson, T. E.; Ha, K. T.; Leong, L.; Iraci, L. T.

    2016-01-01

    Particles in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40–80 wt %) in water. However, airborne measurements have shown that these particles also contain a significant fraction of organic compounds of unknown chemical composition. Acid-catalyzed reactions of carbonyl species are believed to be responsible for significant transfer of gas phase organic species into tropospheric aerosols and are potentially more important at the high acidities characteristic of UT/LS particles. In this study, experiments combining sulfuric acid (H2SO4) with propanal and with mixtures of propanal with glyoxal and/or methylglyoxal at acidities typical of UT/LS aerosols produced highly colored surface films (and solutions) that may have implications for aerosol properties. In order to identify the chemical processes responsible for the formation of the surface films, attenuated total reflectance–Fourier transform infrared (ATR-FTIR) and 1H nuclear magnetic resonance (NMR) spectroscopies were used to analyze the chemical composition of the films. Films formed from propanal were a complex mixture of aldol condensation products, acetals and propanal itself. The major aldol condensation products were the dimer (2-methyl-2-pentenal) and 1,3,5-trimethylbenzene that was formed by cyclization of the linear aldol condensation trimer. Additionally, the strong visible absorption of the films indicates that higher-order aldol condensation products must also be present as minor species. The major acetal species were 2,4,6-triethyl-1,3,5-trioxane and longer-chain linear polyacetals which are likely to separate from the aqueous phase. Films formed on mixtures of propanal with glyoxal and/or methylglyoxal also showed evidence of products of cross-reactions. Since cross-reactions would be more likely than self-reactions under atmospheric conditions, similar reactions of aldehydes like propanal with common aerosol organic species like glyoxal and

  9. Chemical composition of aerosol measurements in the air pollution plume during KORUS-AQ

    Science.gov (United States)

    Park, T.; Lee, J. B.; Lim, Y. J.; Ahn, J.; Park, J. S.; Soo, C. J.; Kim, J.; Park, S.; Lee, Y.; Desyaterik, Y.; Collett, J. L., Jr.; Lee, T.

    2017-12-01

    The Korean peninsula is a great place to study different sources of the aerosols: urban, rural and marine. In addition, Seoul is one of the large metropolitan areas in the world and has a variety of sources because half of the Korean population lives in Seoul, which comprises only 12% of the country's area. To understand the chemical composition of aerosol form long-range transport and local sources better, an Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was deployed on an airborne platform (NASA DC-8 aircraft). The HR-ToF-AMS is capable of measuring non-refractory size resolved chemical composition of submicron particle(NR-PM1) in the air pollution plume, including mass concentration of organic carbon, nitrate, sulfate, and ammonium with 10 seconds time resolution. The measurements were performed twenty times research flight for understanding characteristic of the air pollution from May to June, 2016 on the South Korean peninsula during KORUS-AQ 2016 campaign. The scientific goal of this study is to characterize aerosol chemical properties and mass concentration in order to understand the role of the long-range transport from northeast Asia to South Korea, and influence of the local sources. To brief, organics dominated during all of flights. Also, organics and nitrate were dominant around energy industrial complex near by Taean, South Korea. The presentation will provide an overview of the composition of NR-PM1 measured in air pollution plumes, and deliver detail information about width, depth and spatial distribution of the pollutant in the air pollution plumes. The results of this study will provide high temporal and spatial resolved details on the air pollution plumes, which are valuable input parameters of aerosol properties for the current air quality models.

  10. Spectro-microscopic measurements of carbonaceous aerosol aging in Central California

    Directory of Open Access Journals (Sweden)

    R. C. Moffet

    2013-10-01

    Full Text Available Carbonaceous aerosols are responsible for large uncertainties in climate models, degraded visibility, and adverse health effects. The Carbonaceous Aerosols and Radiative Effects Study (CARES was designed to study carbonaceous aerosols in the natural environment of the Central Valley, California, and learn more about their atmospheric formation and aging. This paper presents results from spectro-microscopic measurements of carbonaceous particles collected during CARES at the time of a pollution accumulation event (27–29 June 2010, when in situ measurements indicated an increase in the organic carbon content of aerosols as the Sacramento urban plume aged. Computer-controlled scanning electron microscopy coupled with an energy dispersive X-ray detector (CCSEM/EDX and scanning transmission X-ray microscopy coupled with near-edge X-ray absorption spectroscopy (STXM/NEXAFS were used to probe the chemical composition and morphology of individual particles. It was found that the mass of organic carbon on individual particles increased through condensation of secondary organic aerosol. STXM/NEXAFS indicated that the number fraction of homogenous organic particles lacking inorganic inclusions (greater than ~50 nm equivalent circular diameter increased with plume age, as did the organic mass per particle. Comparison of the CARES spectro-microscopic dataset with a similar dataset obtained in Mexico City during the MILAGRO campaign showed that fresh particles in Mexico City contained three times as much carbon as those sampled during CARES. The number fraction of soot particles at the Mexico City urban site (ranging from 16.6 to 47.3% was larger than at the CARES urban site (13.4–15.7%, and the most aged samples from CARES contained fewer carbon–carbon double bonds. Differences between carbonaceous particles in Mexico City and California result from different sources, photochemical conditions, gas phase reactants, and secondary organic aerosol

  11. Column Aerosol Optical Properties and Aerosol Radiative Forcing During a Serious Haze-Fog Month over North China Plain in 2013 Based on Ground-Based Sunphotometer Measurements

    Science.gov (United States)

    Che, H.; Xia, X.; Zhu, J.; Li, Z.; Dubovik, O.; Holben, Brent N.; Goloub, P.; Chen, H.; Estelles, V.; Cuevas-Agullo, E.

    2014-01-01

    In January 2013, North China Plain experienced several serious haze events. Cimel sunphotometer measurements at seven sites over rural, suburban and urban regions of North China Plain from 1 to 30 January 2013 were used to further our understanding of spatial-temporal variation of aerosol optical parameters and aerosol radiative forcing (ARF). It was found that Aerosol Optical Depth at 500 nm (AOD500nm) during non-pollution periods at all stations was lower than 0.30 and increased significantly to greater than 1.00 as pollution events developed. The Angstrom exponent (Alpha) was larger than 0.80 for all stations most of the time. AOD500nm averages increased from north to south during both polluted and non-polluted periods on the three urban sites in Beijing. The fine mode AOD during pollution periods is about a factor of 2.5 times larger than that during the non-pollution period at urban sites but a factor of 5.0 at suburban and rural sites. The fine mode fraction of AOD675nm was higher than 80% for all sites during January 2013. The absorption AOD675nm at rural sites was only about 0.01 during pollution periods, while 0.03-0.07 and 0.01-0.03 during pollution and non-pollution periods at other sites, respectively. Single scattering albedo varied between 0.87 and 0.95 during January 2013 over North China Plain. The size distribution showed an obvious tri-peak pattern during the most serious period. The fine mode effective radius in the pollution period was about 0.01-0.08 microns larger than during nonpollution periods, while the coarse mode radius in pollution periods was about 0.06-0.38 microns less than that during nonpollution periods. The total, fine and coarse mode particle volumes varied by about 0.06-0.34 cu microns, 0.03-0.23 cu microns, and 0.03-0.10 cu microns, respectively, throughout January 2013. During the most intense period (1-16 January), ARF at the surface exceeded -50W/sq m, -180W/sq m, and -200W/sq m at rural, suburban, and urban sites

  12. Advancing Solar Irradiance Measurement for Climate-Related Studies: Accurate Constraint on Direct Aerosol Radiative Effect (DARE)

    Science.gov (United States)

    Tsay, Si-Chee; Ji, Q. Jack

    2011-01-01

    Earth's climate is driven primarily by solar radiation. As summarized in various IPCC reports, the global average of radiative forcing for different agents and mechanisms, such as aerosols or CO2 doubling, is in the range of a few W/sq m. However, when solar irradiance is measured by broadband radiometers, such as the fleet of Eppley Precision Solar Pyranometers (PSP) and equivalent instrumentation employed worldwide, the measurement uncertainty is larger than 2% (e.g., WMO specification of pyranometer, 2008). Thus, out of the approx. 184 W/sq m (approx.263 W/sq m if cloud-free) surface solar insolation (Trenberth et al. 2009), the measurement uncertainty is greater than +/-3.6 W/sq m, overwhelming the climate change signals. To discern these signals, less than a 1 % measurement uncertainty is required and is currently achievable only by means of a newly developed methodology employing a modified PSP-like pyranometer and an updated calibration equation to account for its thermal effects (li and Tsay, 2010). In this talk, we will show that some auxiliary measurements, such as those from a collocated pyrgeometer or air temperature sensors, can help correct historical datasets. Additionally, we will also demonstrate that a pyrheliometer is not free of the thermal effect; therefore, comparing to a high cost yet still not thermal-effect-free "direct + diffuse" approach in measuring surface solar irradiance, our new method is more economical, and more likely to be suitable for correcting a wide variety of historical datasets. Modeling simulations will be presented that a corrected solar irradiance measurement has a significant impact on aerosol forcing, and thus plays an important role in climate studies.

  13. Particle Morphology and Size Results from the Smoke Aerosol Measurement Experiment-2

    Science.gov (United States)

    Urban, David L.; Ruff, Gary A.; Greenberg, Paul S.; Fischer, David; Meyer, Marit; Mulholland, George; Yuan, Zeng-Guang; Bryg, Victoria; Cleary, Thomas; Yang, Jiann

    2012-01-01

    Results are presented from the Reflight of the Smoke Aerosol Measurement Experiment (SAME-2) which was conducted during Expedition 24 (July-September 2010). The reflight experiment built upon the results of the original flight during Expedition 15 by adding diagnostic measurements and expanding the test matrix. Five different materials representative of those found in spacecraft (Teflon, Kapton, cotton, silicone rubber and Pyrell) were heated to temperatures below the ignition point with conditions controlled to provide repeatable sample surface temperatures and air flow. The air flow past the sample during the heating period ranged from quiescent to 8 cm/s. The smoke was initially collected in an aging chamber to simulate the transport time from the smoke source to the detector. This effective transport time was varied by holding the smoke in the aging chamber for times ranging from 11 to 1800 s. Smoke particle samples were collected on Transmission Electron Microscope (TEM) grids for post-flight analysis. The TEM grids were analyzed to observe the particle morphology and size parameters. The diagnostics included a prototype two-moment smoke detector and three different measures of moments of the particle size distribution. These moment diagnostics were used to determine the particle number concentration (zeroth moment), the diameter concentration (first moment), and the mass concentration (third moment). These statistics were combined to determine the diameter of average mass and the count mean diameter and, by assuming a log-normal distribution, the geometric mean diameter and the geometric standard deviations can also be calculated. Overall the majority of the average smoke particle sizes were found to be in the 200 nm to 400 nm range with the quiescent cases producing some cases with substantially larger particles.

  14. Aerosol properties over Interior Alaska from lidar, DRUM Impactor sampler, and OPC-sonde measurements and their meteorological context during ARCTAS-A, April 2008

    Science.gov (United States)

    Atkinson, D. E.; Sassen, K.; Hayashi, M.; Cahill, C. F.; Shaw, G.; Harrigan, D.; Fuelberg, H.

    2013-02-01

    Aerosol loading over Interior Alaska displays a strong seasonality, with pristine conditions generally prevailing during winter months. Long term aerosol research from the University of Alaska Fairbanks indicates that the period around April typically marks the beginning of the transition from winter to summer conditions. In April 2008, the NASA-sponsored "Arctic Research of the Composition of the Troposphere from Aircraft and Satellites" (ARCTAS) field campaign was conducted to analyze incursions of aerosols transported over Alaska and the Canadian North. In and around Fairbanks, Alaska, data concerning aerosol characteristics were gathered by polarization (0.693 μm) lidar, DRUM Impactor sampler, and balloon-borne optical particle counter. These data provide information on the vertical distribution and type of aerosol, their size distributions, the chemical nature of aerosol observed at the surface, and timing of aerosol loading. A detailed synoptic analysis placed these observations into their transport and source-region context. Evidence suggests four major aerosol loading periods in the 25 March-30 April 2008 timeframe: a period during which typical Arctic haze conditions prevailed, several days of extremely clear conditions, rapid onset of a period dominated by Asian dust with some smoke, and a period dominated by Siberian wildfire smoke. A focused case study analysis conducted on 19 April 2008 using a balloon-borne optical particle counter suggests that, on this day, the majority of the suspended particulate matter consisted of coarse mode desiccated aerosol having undergone long-range transport. Backtrack trajectory analysis suggests aged Siberian wildfire smoke. In the last week of April, concentrations gradually decreased as synoptic conditions shifted away from favoring transport to Alaska. An important result is a strong suggestion of an Asian dust incursion in mid-April that was not well identified in other ARCTAS measurements. The lidar and OPC

  15. Aerosol properties over Interior Alaska from lidar, DRUM Impactor sampler, and OPC-sonde measurements and their meteorological context during ARCTAS-A, April 2008

    Directory of Open Access Journals (Sweden)

    D. E. Atkinson

    2013-02-01

    Full Text Available Aerosol loading over Interior Alaska displays a strong seasonality, with pristine conditions generally prevailing during winter months. Long term aerosol research from the University of Alaska Fairbanks indicates that the period around April typically marks the beginning of the transition from winter to summer conditions. In April 2008, the NASA-sponsored "Arctic Research of the Composition of the Troposphere from Aircraft and Satellites" (ARCTAS field campaign was conducted to analyze incursions of aerosols transported over Alaska and the Canadian North. In and around Fairbanks, Alaska, data concerning aerosol characteristics were gathered by polarization (0.693 μm lidar, DRUM Impactor sampler, and balloon-borne optical particle counter. These data provide information on the vertical distribution and type of aerosol, their size distributions, the chemical nature of aerosol observed at the surface, and timing of aerosol loading. A detailed synoptic analysis placed these observations into their transport and source-region context. Evidence suggests four major aerosol loading periods in the 25 March–30 April 2008 timeframe: a period during which typical Arctic haze conditions prevailed, several days of extremely clear conditions, rapid onset of a period dominated by Asian dust with some smoke, and a period dominated by Siberian wildfire smoke. A focused case study analysis conducted on 19 April 2008 using a balloon-borne optical particle counter suggests that, on this day, the majority of the suspended particulate matter consisted of coarse mode desiccated aerosol having undergone long-range transport. Backtrack trajectory analysis suggests aged Siberian wildfire smoke. In the last week of April, concentrations gradually decreased as synoptic conditions shifted away from favoring transport to Alaska. An important result is a strong suggestion of an Asian dust incursion in mid-April that was not well identified in other ARCTAS measurements. The

  16. Simultaneous determination of aerosol optical thickness and water-leaving radiance from multispectral measurements in coastal waters

    Science.gov (United States)

    Shi, Chong; Nakajima, Teruyuki

    2018-03-01

    Retrieval of aerosol optical properties and water-leaving radiance over ocean is challenging since the latter mostly accounts for ˜ 10 % of the satellite-observed signal and can be easily influenced by the atmospheric scattering. Such an effort would be more difficult in turbid coastal waters due to the existence of optically complex oceanic substances or high aerosol loading. In an effort to solve such problems, we present an optimization approach for the simultaneous determination of aerosol optical thickness (AOT) and normalized water-leaving radiance (nLw) from multispectral satellite measurements. In this algorithm, a coupled atmosphere-ocean radiative transfer model combined with a comprehensive bio-optical oceanic module is used to jointly simulate the satellite-observed reflectance at the top of atmosphere and water-leaving radiance just above the ocean surface. Then, an optimal estimation method is adopted to retrieve AOT and nLw iteratively. The algorithm is validated using Aerosol Robotic Network - Ocean Color (AERONET-OC) products selected from eight OC sites distributed over different waters, consisting of observations that covered glint and non-glint conditions from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. Results show a good consistency between retrieved and in situ measurements at each site. It is demonstrated that more accurate AOTs are determined based on the simultaneous retrieval method, particularly in shorter wavelengths and sunglint conditions, where the averaged percentage difference (APD) of retrieved AOT is generally reduced by approximate 10 % in visible bands compared with those derived from the standard atmospheric correction (AC) scheme, since all the spectral measurements can be used jointly to increase the information content in the inversion of AOT, and the wind speed is also simultaneously retrieved to compensate the specular reflectance error estimated from the rough ocean surface model. For the

  17. Aerosol Hygroscopicity Distribution and Mixing State Determined by Cloud Condensation Nuclei (CCN) Measurements

    Science.gov (United States)

    Su, H.; Rose, D.; Cheng, Y.; Gunthe, S. S.; Wiedensohler, A.; Andreae, M. O.; Pöschl, U.

    2009-12-01

    This paper presents, firstly the concept of hygroscopicity distribution and its application in the analysis of cloud condensation nuclei (CCN) measurement data. The cumulative particle hygroscopicity distribution function N(κ) is defined as the number concentration of particles with a hygroscopicity parameter, κ, smaller than a certain value of κ. Since the measured CCN (at supersaturation S) can be considered as those particles with κ larger than a certain value, the CCN efficiency spectra (activation curve) can be easily converted to N(κ) distributions. Unlike studies calculating only one hygroscopicity parameter from a CCN activation curve, the concept of N(κ) shows the usefulness of all points on the activation curve. Modeling studies of three assumed N(κ) distributions are used to illustrate the new concept N(κ) and how it is related to the size-resolved CCN measurements. Secondly, we discuss the aerosol mixing state information that can be obtained from the shape of N(κ). A case study is performed based on the CCN measurements during the CAREBEIJING 2006 campaign. In the campaign-averaged N(κ) distribution, most particles (>80%) lie in a mode with a geometric mean κ around 0.2-0.4, and an increasing trend in the mean κ is found as particle size increases. There seems to be another less hygroscopic mode but the κ resolution (depending on the size resolution) in the campaign is not high enough to interpret it. It is also clear that N(κ) is not a monodisperse distribution (implying an internal mixture of the aerosols). The dispersion parameter σg,κ, which is the geometric standard deviation of N(κ), can be used as an indicator for the aerosol mixing state. The indicator σg,κ shows good agreement with the soot mixing state measured by a volatility tandem differential mobility analyzer (VTDMA) during the CAREBEIJING 2006 campaign. The concept of N(κ) can be widely used to study aerosol mixing states, especially in the lab experiment where a

  18. Measurements of non-volatile aerosols with a VTDMA and their correlations with carbonaceous aerosols in Guangzhou, China

    Science.gov (United States)

    Cheung, Heidi H. Y.; Tan, Haobo; Xu, Hanbing; Li, Fei; Wu, Cheng; Yu, Jian Z.; Chan, Chak K.

    2016-07-01

    Simultaneous measurements of aerosol volatility and carbonaceous matters were conducted at a suburban site in Guangzhou, China, in February and March 2014 using a volatility tandem differential mobility analyzer (VTDMA) and an organic carbon/elemental carbon (OC / EC) analyzer. Low volatility (LV) particles, with a volatility shrink factor (VSF) at 300 °C exceeding 0.9, contributed 5 % of number concentrations of the 40 nm particles and 11-15 % of the 80-300 nm particles. They were composed of non-volatile material externally mixed with volatile material, and therefore did not evaporate significantly at 300 °C. Non-volatile material mixed internally with the volatile material was referred to as medium volatility (MV, 0.4 transported at low altitudes (below 1500 m) for over 40 h before arrival. Further comparison with the diurnal variations in the mass fractions of EC and the non-volatile OC in PM2.5 suggests that the non-volatile residuals may be related to both EC and non-volatile OC in the afternoon, during which the concentration of aged organics increased. A closure analysis of the total mass of LV and MV residuals and the mass of EC or the sum of EC and non-volatile OC was conducted. It suggests that non-volatile OC, in addition to EC, was one of the components of the non-volatile residuals measured by the VTDMA in this study.

  19. Nonlinear effects of anthropogenic aerosol and urban land surface forcing on spring climate in eastern China

    Science.gov (United States)

    Deng, Jiechun; Xu, Haiming; Zhang, Leying

    2016-05-01

    Anthropogenic aerosols and urban land cover change induce opposite thermal effects on the atmosphere near surface as well as in the troposphere. One can think of these anthropogenic effects as composed of two parts: the individual effect due to an individual anthropogenic forcing and the nonlinear effects resulting from the coexistence of two forcing factors. In this study, we explored the role of such nonlinear effects in affecting East Asian climate, as well as individual forcing effects, using the Community Atmosphere Model version 5.1 coupled with the Community Land Model version 4. Atmospheric responses were simulated by including anthropogenic aerosol emission only, urban cover only, or the combination of the two, over eastern China. Results showed that nonlinear responses were different from any effects by an individual forcing or the linear combination of individual responses. The nonlinear interaction could generate cold horizontal temperature advection to cool the troposphere, which induced anomalous subsidence along the Yangtze River Valley (YRV). This anomalous vertical motion, together with a weakened low-level southwesterly, favored below-normal (above-normal) rainfall over the YRV (southern China), shifting the spring rain belt southward. The resultant diabatic cooling, in turn, amplified the anomalous descent and further decreased tropospheric temperature over the YRV, forming a positive feedback loop to maintain the nonlinear effects. Consequently, the nonlinear effects acted to reduce the climate anomalies from a simple linear combination of two individual effects and played an important role in regional responses to one anthropogenic forcing when the other is prescribed.

  20. Link between aerosol optical, microphysical and chemical measurements in an underground railway station in Paris

    Science.gov (United States)

    Raut, J.-C.; Chazette, P.; Fortain, A.

    Measurements carried out in Paris Magenta railway station in April-May 2006 underlined a repeatable diurnal cycle of aerosol concentrations and optical properties. The average daytime PM 10 and PM 2.5 concentrations in such a confined space were approximately 5-30 times higher than those measured in Paris streets. Particles are mainly constituted of dust, with high concentrations of iron and other metals, but are also composed of black and organic carbon. Aerosol levels are linked to the rate at which rain and people pass through the station. Concentrations are also influenced by ambient air from the nearby streets through tunnel ventilation. During daytime approximately 70% of aerosol mass concentrations are governed by coarse absorbing particles with a low Angström exponent (˜0.8) and a low single-scattering albedo (˜0.7). The corresponding aerosol density is about 2 g cm -3 and their complex refractive index at 355 nm is close to 1.56-0.035 i. The high absorption properties are linked to the significant proportion of iron oxides together with black carbon in braking systems. During the night, particles are mostly submicronic, thus presenting a greater Angström exponent (˜2). The aerosol density is lower (1.8 g cm -3) and their complex refractive index presents a lower imaginary part (1.58-0.013 i), associated to a stronger single-scattering albedo (˜0.85-0.90), mostly influenced by the ambient air. For the first time we have assessed the emission (deposition) rates in an underground station for PM 10, PM 2.5 and black carbon concentrations to be 3314 ± 781(-1164 ± 160), 1186 ± 358(-401 ± 66) and 167 ± 46(-25 ± 9) μg m -2 h -1, respectively.

  1. 403 nm cavity ring-down measurements of brown carbon aerosol

    Science.gov (United States)

    Kwon, D.; Grassian, V. H.; Kleiber, P.; Young, M. A.

    2017-12-01

    Atmospheric aerosol influences Earth's climate by absorbing and scattering incoming solar radiation and outgoing terrestrial radiation. One class of secondary organic aerosol (SOA), called brown carbon (BrC), has attracted attention for its wavelength dependent light absorbing properties with absorption coefficients that generally increase from the visible (Vis) to ultraviolet (UV) regions. Here we report results from our investigation of the optical properties of BrC aerosol products from the aqueous phase reaction of ammonium sulfate (AS) with methylglyoxal (MG) using cavity ring-down spectroscopy (CRDS) at 403 nm wavelength. We have measured the optical constants of BrC SOA from the AS/MG reaction as a function of reaction time. Under dry flow conditions, we observed no apparent variation in the BrC refractive index with aging over the course of 22 days. The retrieved BrC optical constants are similar to those of AS with n = 1.52 for the real component. Despite significant UV absorption observed from the bulk BrC solution, the imaginary index value at 403 nm is below our minimum detection limit which puts an upper bound of k as 0.03. These observations are in agreement with results from our recent studies of the light scattering properties of this BrC aerosol.

  2. Measurements and estimation of the columnar optical depth of tropospheric aerosols in the UV spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Cachorro, V.E.; Vergaz, R.; Martin, M.J.; Frutos, A.M. de [Grupo de Optica Atmosferica, Univ. de Valladolid (GOA-UVA), Valladolid (Spain); Vilaplana, J.M.; Morena, B. de la [Estacion de Sondeos Atmosfericos ESAT ' ' El Arenosillo' ' , INTA, Huelva (Spain)

    2002-04-01

    We report values of the columnar tropospheric aerosol optical depth at UV wavelengths based on experimental measurements of the direct spectral irradiances carried out by a commercial spectroradiometer (Li1800 of Licor company) covering the range from 300-1100 nm at two stations with different climate characteristics in Spain. The first station is located in a rural site in north central Spain with continental climate. The data extend from March to the end of October of 1995. The other station is a coastal site in the Gulf of Cadiz (southwest Spain) of maritime climate type. This study is mainly focused on the capability of estimating aerosol optical depth values in the UV region based on the extracted information in the visible and near infrared ranges. A first method has been used based on the Aangstroem turbidity parameters. However, since this method requires detailed spectral information, a second method has also been used, based on the correlation between wavelengths. A correlation has been established between the experimental aerosol optical depth values at 350 nm and 500 nm wavelengths. Although the type of aerosol seems to be the key factor that determines the quality of these estimations, the evaluation of the associated error is necessary to know the behavior of these estimations in each area of study. (orig.)

  3. Online Measurements of Water-Soluble Iron in Ambient Aerosols: A new Technique

    Science.gov (United States)

    Rastogi, N.; Oakes, M.; Weber, R. J.; Majestic, B. J.; Shafer, M. M.; Snyder, D. C.; Schauer, J. J.

    2008-05-01

    Water-soluble iron, i.e. Fe(II) (hereafter, WS-Fe), is a redox active metal that can act as a catalyst in the production of reactive oxygen species (ROS). In atmospheric aerosol particles, WS-Fe may significantly impact human health and the atmospheric oxidative capacity. Further, WS-Fe acts as a critical nutrient for marine organisms and has been hypothesized to limit phytoplankton productivity in high nitrate, low-chlorophyll ocean regions. In order to assess the role of aerosol WS-Fe on human health, atmospheric chemistry and ocean biogeochemistry, it is necessary to understand its major sources, transport, transformation processes and sinks. Filter-based measurements with several (6-24) hours integration time are predominately used to quantify WS-Fe in aerosols but provide limited insight into acute exposures that could be higher than daily averages, or sources having high temporal variability. Generally, mineral dust and its processing with acidic pollutants, is considered the dominant source of WS-Fe, however, recent studies have reported combustion emissions are also a possible source. A time-resolved data set may help in identifying WS-Fe sources, atmospheric transformations and possible sinks. We have developed a new system for online quantitative analyses of WS-Fe present in ambient aerosols with a 12-minute integration time. It mainly consists of Particle-Into-Liquid Sampler (PILS), a liquid waveguide capillary cell (LWCC) and a portable UV-Visible spectrophotometer. The complete system is automated so that first the liquid sample (water-extract of ambient aerosols from PILS) is mixed with ferrozine (complexing reagent) by pumping them simultaneously (10:1) through a serpentine reactor and a 100 turn mixing coil using a peristaltic pump. After holding the mixed solution in the mixing coil for three minutes, the sample is pumped through the LWCC and held there for two minutes to acquire the absorbance of the solution at 562 nm (for Fe

  4. An inverse modeling procedure to determine particle growth and nucleation rates from measured aerosol size distributions

    Directory of Open Access Journals (Sweden)

    B. Verheggen

    2006-01-01

    Full Text Available Classical nucleation theory is unable to explain the ubiquity of nucleation events observed in the atmosphere. This shows a need for an empirical determination of the nucleation rate. Here we present a novel inverse modeling procedure to determine particle nucleation and growth rates based on consecutive measurements of the aerosol size distribution. The particle growth rate is determined by regression analysis of the measured change in the aerosol size distribution over time, taking into account the effects of processes such as coagulation, deposition and/or dilution. This allows the growth rate to be determined with a higher time-resolution than can be deduced from inspecting contour plots ('banana-plots''. Knowing the growth rate as a function of time enables the evaluation of the time of nucleation of measured particles of a certain size. The nucleation rate is then obtained by integrating the particle losses from time of measurement to time of nucleation. The regression analysis can also be used to determine or verify the optimum value of other parameters of interest, such as the wall loss or coagulation rate constants. As an example, the method is applied to smog chamber measurements. This program offers a powerful interpretive tool to study empirical aerosol population dynamics in general, and nucleation and growth in particular.

  5. Mass transfer effects in hygroscopic measurements of aerosol particles

    Directory of Open Access Journals (Sweden)

    M. N. Chan

    2005-01-01

    Full Text Available The tandem differential mobility analyzer (TDMA has been widely utilized to measure the hygroscopicity of laboratory-generated and atmospheric submicrometer particles. An important concern in investigating the hygroscopicity of the particles is if the particles have attained equilibrium state in the measurements. We present a literature survey to investigate the mass transfer effects in hygroscopicity measurements. In most TDMA studies, a residence time in the order of seconds is used for humidification (or dehumidification. NaCl and (NH42SO4 particles are usually used to verify the equilibrium measurements during this residence time, which is presumed to be sufficient for other particles. There have been observations that not all types of submicrometer particles, including atmospheric particles, attain their equilibrium sizes within this time scale. We recommend that experimentation with different residence times be conducted and that the residence time should be explicitly stated in future TDMA measurements. Mass transfer effects may also exist in the measurements of other properties related to the water uptake of atmospheric particles such as relative humidity dependent light scattering coefficients and cloud condensation nuclei activity.

  6. Aerosol Optical and Microphysical Properties of Four Typical Sites of SONET in China Based on Remote Sensing Measurements

    Directory of Open Access Journals (Sweden)

    Yisong Xie

    2015-08-01

    Full Text Available The current understanding of columnar aerosol optical and microphysical properties of different regions and seasons in China is insufficient due to the lack of measurements. Aiming to improve descriptions of aerosol models over China, this paper presents a systematic aerosol characterization of different sites based on a newly developed remote sensing network for aerosol observation, the Sun-sky radiometer Observation NETwork (SONET. One year of ground-based solar and sky radiation measurements of four typical sites of SONET (Beijing–urban-industrial site, Zhangye—rural site, Minqin—desert site, Zhoushan–oceanic site are used to retrieve aerosol properties using similar inversion algorithms with AErosol RObotic NETwork (AERONET, including aerosol optical depth, Ångström exponent, volume size distribution, complex refractive index, single scattering albedo, and percentage of spherical particles. The retrieved properties among sites and seasons are found to be different in terms of magnitude, spectral dependence, and partition of fine and coarse mode, which can be primarily explained by different aerosol composition and mixing states that closely relate to the local climate, the natural environment, and most importantly, the ubiquitous anthropogenic impacts. For example, large dust particles greatly contribute to the low fine mode fraction in both volume concentration and optical depth for the Minqin site through the entire year, while abundant small particles that mainly come from emission sources dominate the size distribution and light extinction of aerosol in the summer at the Beijing site. The results also show general agreements with other studies on the aerosol properties at each site, however, some unique features are still noticeable, especially at the desert site and oceanic site (e.g., the unusually strong aerosol absorptivity indicated by the large imaginary refractive index and low single scattering albedo at the Minqin and

  7. Surface charge measurement by the Pockels effect

    CERN Document Server

    Sam, Y L

    2001-01-01

    have been observed by applying both impulse and AC voltages to a needle electrode in direct contact with the BSO. AC surface discharge behaviour of polymeric materials bonded to the BSO has also been investigated. The effect of the surrounding environment has been experimentally examined by placing the cell inside a vacuum chamber. Surface charge measurements have been made at various atmospheric pressures. The effect of an electro-negative gas (Sulphur Hexafluoride) on the surface charge distribution has also been investigated. This thesis is concerned with the design and development of a surface charge measurement system using Pockels effect. The measurement of surface charge is important in determining the electrical performance of high voltage insulation materials. The method proposed allows on-line measurement of charge and can generate two-dimensional images that represent the charge behaviour on the surface of the material under test. The measurement system is optical and uses a Pockels crystal as the ...

  8. Daily and seasonal variation of aerosol concentration in the atmosphere near the surface in continental climate of Siberia

    Energy Technology Data Exchange (ETDEWEB)

    Koutsenogii, P. [Inst. of Chemical Kinetics and Combustion, Novosibirsk (Russian Federation)

    1995-12-31

    Novosibirsk region is the area in southern part of West-Siberian lowland, covering about 200,000 km{sup 2}. The properties of atmospheric aerosol in Novosibirsk region were studied during few campaigns in the years 1992 and 1993, one complex expedition in Summer of 1994 and durable observations in Akademgorodok in the years 1993, 1994. Akademgorodok is situated 25 km S from the city Novosibirsk, has population of about 100,000 and no industry. Three different locations in remote areas of Novosibirsk region were used for the measurements. The first was situated 12 km E from Akademgorodok, and 30 km from Novosibirsk near the village Kljutchi. The second location was situated close to Lake Tchany in western part of Novosibirsk region. The third location was situated in south-western part of Novosibirsk region, 12 km from the town Karasuk. The total aerosol light scattering by aerosol particles was measured by commercially available nephelometer FAN-A in terms of units, related to the molecular scattering of clean air, measured by the same nephelometer. Aerosol samples in which the content of sulfate-, nitrate-, and cloride-anions was determined, using ion liquid chromatography, were collected with Whatman 41 or AFA-HA filters. Aerosol mass concentration was measured by weighting of AFA-HA filters. Aerosol particles were sampled on the filters with the volume velocity of about 500 l/min for Whatman 41 and 120 l/min for AFA-HA and mean sampling duration of 24 hours. The total aerosol number concentration was measured with a condensation nuclei counter TSI 3020

  9. Measured and predicted aerosol light scattering enhancement factors at the high alpine site Jungfraujoch

    Directory of Open Access Journals (Sweden)

    R. Fierz-Schmidhauser

    2010-03-01

    Full Text Available Ambient relative humidity (RH determines the water content of atmospheric aerosol particles and thus has an important influence on the amount of visible light scattered by particles. The RH dependence of the particle light scattering coefficient (σsp is therefore an important variable for climate forcing calculations. We used a humidification system for a nephelometer which allows for the measurement of σsp at a defined RH in the range of 20–95%. In this paper we present measurements of light scattering enhancement factors f(RH=σsp(RH/σsp(dry from a 1-month campaign (May 2008 at the high alpine site Jungfraujoch (3580 m a.s.l., Switzerland. Measurements at the Jungfraujoch are representative for the lower free troposphere above Central Europe. For this aerosol type hardly any information about the f(RH is available so far. At this site, f(RH=85% varied between 1.2 and 3.3. Measured f(RH agreed well with f(RH calculated with Mie theory using measurements of the size distribution, chemical composition and hygroscopic diameter growth factors as input. Good f(RH predictions at RH<85% were also obtained with a simplified model, which uses the Ångström exponent of σsp(dry as input. RH influences further intensive optical aerosol properties. The backscatter fraction decreased by about 30% from 0.128 to 0.089, and the single scattering albedo increased on average by 0.05 at 85% RH compared to dry conditions. These changes in σsp, backscatter fraction and single scattering albedo have a distinct impact on the radiative forcing of the Jungfraujoch aerosol.

  10. Biogenic contribution to PM-2.5 ambient aerosol from radiocarbon measurements

    Science.gov (United States)

    Lewis, C.; Klouda, G.; Ellenson, W.

    2003-04-01

    Knowledge of the relative contributions of biogenic versus anthropogenic sources to ambient aerosol is of great interest in the formulation of strategies to achieve nationally mandated air quality standards. Radiocarbon (14C) measurements provide a means to quantify the biogenic fraction of any carbon-containing sample of ambient aerosol. In the absence of an impact from biomass burning (e.g., during summertime) such measurements can provide an estimate of the contribution of biogenic secondary organic aerosol, from biogenic volatile organic compound precursors. Radiocarbon results for 11.5-h PM-2.5 samples collected near Nashville, Tennessee, USA, during summer 1999 will be presented. On average the measured biogenic fraction was surprisingly large (more than half), with the average biogenic fraction for night samples being only slightly smaller than for day samples. Discussion will include (a) description of the radiocarbon methodology, (b) use of radiocarbon measurements on local vegetation and fuel samples as calibration data, (c) concurrent measurements of organic carbon and elemental carbon ambient concentrations, (d) assessment of organic aerosol sampling artifact through use of organic vapor denuders, variable face velocities, and filter extraction, and (e) comparison with published radiocarbon results obtained in Houston, Texas in a similar study. Disclaimer: This work has been funded wholly or in part by the United States Environmental Protection Agency under Interagency Agreement No. 13937923 to the National Institute of Standards and Technology, and Contract No. 68-D5-0049 to ManTech Environmental Tecnology, Inc. It has been subjected to Agency review and approved for publication.

  11. Increase of surface solar irradiance across East China related to changes in aerosol properties during the past decade

    Science.gov (United States)

    Li, Jing; Jiang, Yiwei; Xia, Xiangao; Hu, Yongyun

    2018-03-01

    Previously, it was widely documented that an overall decrease in surface solar radiation occurred in China at least until 2005, in contrast to the general background of ‘global brightening’. Increased anthropogenic aerosol emissions were speculated to be the source of the reduction. In this study, we extend the trend analysis to the most recent decade from 2005-2015 and find that surface solar radiation has shifted from ‘dimming’ to ‘brightening’ over East China, with the largest increase over the northeast and southeast parts. Meanwhile, satellite and ground observation both indicate a reduction in aerosol optical depth (AOD) during the same period, whereas no significant trends in cloud amount show up. Detailed analysis using co-located radiation and aerosol observation at the XiangHe station in North China suggests that both AOD and single scattering albedo (SSA) changes contribute to the radiation trends. AOD reduction contributes to the increase of direct solar radiation, also decreasing the diffuse radiation, while the increase of SSA serves to increase the diffuse fraction. Simple calculations using a radiative transfer model confirm that the two effects combined explain changes in the global solar radiation and its components effectively. Our results have implications for potential climate effects with the reduction of China’s aerosol emissions, and the necessity to monitor aerosol composition in addition to its loading.

  12. Analysis of shipboard aerosol optical thickness measurements from multiple sunphotometers aboard the R/V Ronald H. Brown during the Aerosol Characterization Experiment - Asia

    International Nuclear Information System (INIS)

    Miller, Mark A.; Knobelspiesse, Kirk; Frouin, Robert; Bartholomew, Mary Jane; Reynolds, R. Michael; Pietras, Christophe; Fargion, Giulietta; Quinn, Patricia; Thieuleux, Francois

    2005-01-01

    Marine sunphotometer measurements collected aboard the R/V Ronald H. Brown during the Aerosol Characterization Experiment - Asia (ACE-Asia) are used to evaluate the ability of complementary instrumentation to obtain the best possible estimates of aerosol optical thickness and Angstrom exponent from ships at sea. A wide range of aerosol conditions, including clean maritime conditions and highly polluted coastal environments, were encountered during the ACE-Asia cruise. The results of this study suggest that shipboard hand-held sunphotometers and fast-rotating shadow-band radiometers (FRSRs) yield similar measurements and uncertainties if proper measurement protocols are used and if the instruments are properly calibrated. The automated FRSR has significantly better temporal resolution (2 min) than the hand-held sunphotometers when standard measurement protocols are used, so it more faithfully represents the variability of the local aerosol structure in polluted regions. Conversely, results suggest that the hand-held sunphotometers may perform better in clean, maritime air masses for unknown reasons. Results also show that the statistical distribution of the Angstrom exponent measurements is different when the distributions from hand-held sunphotometers are compared with those from the FRSR and that the differences may arise from a combination of factors

  13. Airborne Measurements of Hydrocarbons and Aerosols in the Puget Sound Airshed

    Science.gov (United States)

    Jobson, T.; Laulainen, N.; Laskin, A.; Cowin, J.; Barchet, R.; Barrie, L.; Westberg, H.; Covert, D.; Alexander, M.; Spicer, C.; Joseph, D.

    2002-12-01

    In August 2001, a gas and aerosol measurement campaign was undertaken in Puget Sound from south of Seattle north to the Canadian border. The US DOE Gulfstream 1 aircraft was used to measure meteorological parameters, aerosols and their gaseous precursors. The objectives of this study were to better understand the transport and formation of ozone and particulate matter in the Puget Sound airshed and to develop air quality and meteorological databases for evaluating air quality models used in predicting air quality within this area. The study was coordinated with the Canadian Pacific 2001 study. Real time measurements were made of aerosol number distributions from 3 to 3000 nm diameter and of selected gaseous precursors using standard instrumentation as well as a new proton transfer reaction mass spectrometer. Reactive hydrocarbon compounds, nitrogen oxides, sulphur dioxide, carbon monoxide and ozone were measured on horizontal transects and vertical profiles around Puget Sound in morning and afternoon. Using these observations, this paper will highlight common air quality features as well as some of the complexities related to air quality in a mountain-ringed basin.

  14. Remote Measurement of Pollution-A 40-Year Langley Retrospective. Part 2; Aerosols and Clouds

    Science.gov (United States)

    Remsberg, Ellis E.

    2012-01-01

    A workshop was convened in 1971 by the National Aeronautics and Space Administration (NASA) on the Remote Measurement of Pollution (RMOP), and the findings and recommendations of its participants are in a NASA Special Publication (NASA SP-285). The three primary workshop panels and their chairmen were focused on trace gas species (Will Kellogg), atmospheric particulates or aerosols (Verner Suomi), and water pollution (Gifford Ewing). Many of the workshop participants were specialists in the techniques that might be employed for regional to global-scale, remote measurements of the atmospheric parameters from Earth-orbiting satellites. In 2011 the author published a 40-year retrospective (or Part I) of the instrumental developments that were an outgrowth of the RMOP panel headed by Will Kellogg, i.e., on atmospheric temperature and gaseous species. The current report (or Part II) is an analogous retrospective of the vision of the panel led by Verner Suomi for the measurement of particulates (or aerosols) and clouds and for their effects on Earth s radiation budget. The class of measurement techniques includes laser radar or lidar, solar occultation, limb emission and scattering, nadir-viewing photometry or radiometry, and aerosol polarimetry. In addition, the retrospective refers to the scientific imperatives that led to those instrument developments of 1971-2010. Contributions of the atmospheric technologists at the Langley Research Center are emphasized, and their progress is placed in the context of the parallel and complementary work from within the larger atmospheric science community.

  15. Results Of Aerosol Measurements In An Austrian Road Tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Imhof, D.; Weingartner, E.; Prevot, A.S.H.; Ordonez, C.; Kurtenbach, R. [BUGHW (Georgia); Rodler, J. [TUG Institute (Australia); Sturm, P. [TUG Institute (Australia); Sjoedin, A. [IVL Institute (Sweden); McCrae, I. [TRL Institute (United Kingdom); Baltensperger, U.

    2005-03-01

    In a comprehensive tunnel study in Graz, Austria, measurements of the particulate and gaseous vehicle emissions were performed in the Plabutsch tunnel. This work was a collaboration of PSI with the Technical University of Graz (TUG), the Bergische Universitaet und Gesamthochschule Wuppertal (BUGHW), the Transport Research Laboratory (TRL) in UK and the Swedish Environmental Research Institute (IVL). (author)

  16. Extensive aerosol optical properties and aerosol mass related measurements during TRAMP/TexAQS 2006 - Implications for PM compliance and planning

    Science.gov (United States)

    Wright, Monica E.; Atkinson, Dean B.; Ziemba, Luke; Griffin, Robert; Hiranuma, Naruki; Brooks, Sarah; Lefer, Barry; Flynn, James; Perna, Ryan; Rappenglück, Bernhard; Luke, Winston; Kelley, Paul

    2010-10-01

    Extensive aerosol optical properties, particle size distributions, and Aerodyne quadrupole aerosol mass spectrometer measurements collected during TRAMP/TexAQS 2006 were examined in light of collocated meteorological and chemical measurements. Much of the evident variability in the observed aerosol-related air quality is due to changing synoptic meteorological situations that direct emissions from various sources to the TRAMP site near the center of the Houston-Galveston-Brazoria (HGB) metropolitan area. In this study, five distinct long-term periods have been identified. During each of these periods, observed aerosol properties have implications that are of interest to environmental quality management agencies. During three of the periods, long range transport (LRT), both intra-continental and intercontinental, appears to have played an important role in producing the observed aerosol. During late August 2006, southerly winds brought super-micron Saharan dust and sea salt to the HGB area, adding mass to fine particulate matter (PM 2.5) measurements, but apparently not affecting secondary particle growth or gas-phase air pollution. A second type of LRT was associated with northerly winds in early September 2006 and with increased ozone and sub-micron particulate matter in the HGB area. Later in the study, LRT of emissions from wildfires appeared to increase the abundance of absorbing aerosols (and carbon monoxide and other chemical tracers) in the HGB area. However, the greatest impacts on Houston PM 2.5 air quality are caused by periods with low-wind-speed sea breeze circulation or winds that directly transport pollutants from major industrial areas, i.e., the Houston Ship Channel, into the city center.

  17. Distributed modeling of surface solar radiation based on aerosol optical depth and sunshine duration in China

    Science.gov (United States)

    Zeng, Xiaofan; Zhao, Na; Ma, Yue

    2018-02-01

    Surface solar radiation, as a major component of energy balance, is an important driving condition for nutrient and energy cycle in the Earth system. The spatial distribution of total solar radiation at 10 km×10 km resolution in China was simulated with Aerosol Optical Depth (AOD) data from remote sensing and observing sunshine hours data from ground meteorological stations based on Geographic Information System (GIS). The results showed that the solar radiation was significantly different in the country, and affected by both sunshine hours and AOD. Sunshine hours are higher in the Northwest than that in the Northeast, but solar radiation is lower because of the higher AOD, especially in autumn and winter. It was suggested that the calculation accuracy of solar radiation was limited if just based on sunshine hours, and AOD can be considered as the influencing factor which would help to improve the simulation accuracy of the total solar radiation and realize the solar radiation distributed simulation.

  18. Long-term measurements of aerosol optical parameters in Athens, Greece

    Science.gov (United States)

    Paraskevopoulou, Despoina; Liakakou, Eleni; Gerasopoulos, Evangelos; Mihalopoulos, Nikolaos

    2015-04-01

    Aerosol chemical composition was studied in conjunction with its optical properties in the area of Athens Greece. For this purpose, sampling of fine aerosol fraction (PM2,5) took place on a daily basis from August 2010 to April 2013 at an urban background location. The samples are subsequently analyzed for their content in organic (OC) and elemental carbon (EC), major ions and trace metals, resulting in the exercise of chemical mass closure. In parallel, the optical properties of aerosols are recorded using a nephelometer and a particle soot absorption photometer (PSAP), leading to the calculation of scattering (σscat) and absorption (σabs) coefficients, respectively; while single scattering albedo (SSA) and mass scattering and absorption efficiencies are thereinafter calculated. Daily σscat values provide an average of 30.1±3.9 Μm-1 while, the average of σabs is 5.2±1.4 Μm-1. The seasonal cycle of σscat presents maximum during summer and in November, due to long-range transport of aerosol from continental Europe and dust transfer from Africa, respectively. The estimated mass absorption efficiency of EC is estimated to be 8.3±0.2 m2 g-1 for the whole studied period, while the corresponding estimated mass scattering efficiency of PM2.5 is 1.7±0.1 m2 g-1 and does not affected by the presence of dust. The average SSA equals to 0.87±0.11 for the three-year period. On a seasonal basis, SSA presents maximum values during summer that is consistent with the reduction of EC - the main absorbing specie. Finally, the reconstruction of scattering coefficients was performed taking into consideration the measured chemistry of fine aerosol.

  19. Comparison of PMCAMx aerosol optical depth predictions over Europe with AERONET and MODIS measurements

    Directory of Open Access Journals (Sweden)

    A. Panagiotopoulou

    2016-11-01

    Full Text Available The ability of chemical transport model (CTM PMCAMx to reproduce aerosol optical depth (AOD measurements by the Aerosol Robotic Network (AERONET and the Moderate Resolution Imaging Spectroradiometer (MODIS over Europe during the photochemically active period of May 2008 (EUCAARI campaign is evaluated. Periods with high dust or sea-salt levels are excluded, so the analysis focuses on the ability of the model to simulate the mostly secondary aerosol and its interactions with water. PMCAMx reproduces the monthly mean MODIS and AERONET AOD values over the Iberian Peninsula, the British Isles, central Europe, and Russia with a fractional bias of less than 15 % and a fractional error of less than 30 %. However, the model overestimates the AOD over northern Europe, most probably due to an overestimation of organic aerosol and sulfates. At the other end, PMCAMx underestimates the monthly mean MODIS AOD over the Balkans, the Mediterranean, and the South Atlantic. These errors appear to be related to an underestimation of sulfates. Sensitivity tests indicate that the evaluation results of the monthly mean AODs are quite sensitive to the relative humidity (RH fields used by PMCAMx, but are not sensitive to the simulated size distribution and the black carbon mixing state. The screening of the satellite retrievals for periods with high dust (or coarse particles in general concentrations as well as the combination of the MODIS and AERONET datasets lead to more robust conclusions about the ability of the model to simulate the secondary aerosol components that dominate the AOD during this period.

  20. Combining Multi-Sensor Measurements and Models to Constrain Time-Varying Aerosol Fire Emissions

    Science.gov (United States)

    Cohen, J. B.

    2013-12-01

    A significant portion of global Black Carbon (BC) and Organic Carbon (OC) aerosols are emitted into the atmosphere due to fires. However, due to their spatially and temporally heterogeneous nature, quantifying these emissions has proven to be difficult. Some of the problems stem from variability over multiple spatial and temporal scales: ranging from kilometers in size to thousands of kilometers in impact, and from month-to-month variations in the burning season to interannual variation in overall fire strength which follows such global phenomena as El-Nino. Yet, because of the unique absorbing properties that these aerosols have, they leave a distinct impact on the regional and global climate system, as well as the ability to intensely impact human health in downwind areas, proper quantification of the emissions is absolutely essential. To achieve such a critical understanding of their emissions in space and time, a start-of-the art modelling system of their chemical and physical processing, transport, and removal is implemented. This system is capable of effectively and uniquely simulating many impacts important in the atmosphere, including: enhanced absorption associated with internal mixing, mass and number conservation, the direct and semi-direct effects on atmospheric dynamics and circulation, and appropriate non-linear consideration of urban-scale chemical and physical processing. This modelling system has been used in connection with 3 separate sources of data, to achieve an end product that is heavily dependent on both. First of all, the model has been run in a data-assimilation mode to constrain the annual-average emissions of BC using the Kalman Filter technique. This global constraint, the first of its type, relies heavily on ground-based sensors from NASA as well as other organizations. Secondly, data of the decadal-scale variation in aerosol optical depth, surface reflectance, and radiative power have been obtained from the MODIS and MISR sensors

  1. Rigorous bounds on aerosol optical properties from measurement and/or model constraints

    Science.gov (United States)

    McGraw, Robert; Fierce, Laura

    2016-04-01

    Sparse-particle aerosol models are an attractive alternative to sectional and modal methods for representation of complex, generally mixed particle populations. In the quadrature method of moments (QMOM) a small set of abscissas and weights, determined from distributional moments, provides the sparse set. Linear programming (LP) yields a generalization of the QMOM that is especially convenient for sparse particle selection. In this paper we use LP to obtain rigorous, nested upper and lower bounds to aerosol optical properties in terms of a prescribed Bayesian-like sequence of model or simulated measurement constraints. Examples of such constraints include remotely-sensed light extinction at different wavelengths, modeled particulate mass, etc. Successive reduction in bound separation with each added constraint provides a quantitative measure of its contextual information content. The present study is focused on univariate populations as a first step towards development of new simulation algorithms for tracking the physical and optical properties of multivariate particle populations.

  2. Gaseous ion-composition measurements in the young exhaust plume of jet aircraft at cruising altitudes. Implications for aerosols and gaseous sulfuric acid

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, F.; Wohlfrom, K.H.; Klemm, M.; Schneider, J.; Gollinger, K. [Max-Planck-Inst. for Nuclear Physics, Heidelberg (Germany); Schumann, U.; Busen, R. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Wessling (Germany). Inst. fuer Physik der Atmosphaere

    1997-12-31

    Mass spectrometric measurements were made in the young exhaust plume of an Airbus (A310) at cruising altitudes at distances between 400 and 800 m behind the Airbus (averaged plume age: 3.4 sec). The measurements indicate that gaseous sulfuric acid (GSA) number densities were less than 1.3 x 10{sup 8} cm{sup -3} which is smaller than the expected total sulfuric acid. Hence the missing sulfuric acid must have been in the aerosol phase. These measurements also indicate a total aerosol surface area density A{sub T} {<=} 5.4 x 10{sup -5} cm{sup 2} per cm{sup 3} which is consistent with simultaneously measured soot and water contrail particles. However, homogeneous nucleation leading to (H{sub 2}SO{sub 4}){sub x}(H{sub 2}O){sub y}-clusters can not be ruled out. (author) 16 refs.

  3. GRIP LANGLEY AEROSOL RESEARCH GROUP EXPERIMENT (LARGE) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — Langley Aerosol Research Group Experiment (LARGE) measures ultrafine aerosol number density, total and non-volatile aerosol number density, dry aerosol size...

  4. Estimation of the volatility distribution of organic aerosol combining thermodenuder and isothermal dilution measurements

    Directory of Open Access Journals (Sweden)

    E. E. Louvaris

    2017-10-01

    Full Text Available A method is developed following the work of Grieshop et al. (2009 for the determination of the organic aerosol (OA volatility distribution combining thermodenuder (TD and isothermal dilution measurements. The approach was tested in experiments that were conducted in a smog chamber using organic aerosol (OA produced during meat charbroiling. A TD was operated at temperatures ranging from 25 to 250 °C with a 14 s centerline residence time coupled to a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS and a scanning mobility particle sizer (SMPS. In parallel, a dilution chamber filled with clean air was used to dilute isothermally the aerosol of the larger chamber by approximately a factor of 10. The OA mass fraction remaining was measured as a function of temperature in the TD and as a function of time in the isothermal dilution chamber. These two sets of measurements were used together to estimate the volatility distribution of the OA and its effective vaporization enthalpy and accommodation coefficient. In the isothermal dilution experiments approximately 20 % of the OA evaporated within 15 min. Almost all the OA evaporated in the TD at approximately 200 °C. The resulting volatility distributions suggested that around 60–75 % of the cooking OA (COA at concentrations around 500 µg m−3 consisted of low-volatility organic compounds (LVOCs, 20–30 % of semivolatile organic compounds (SVOCs, and around 10 % of intermediate-volatility organic compounds (IVOCs. The estimated effective vaporization enthalpy of COA was 100 ± 20 kJ mol−1 and the effective accommodation coefficient was 0.06–0.07. Addition of the dilution measurements to the TD data results in a lower uncertainty of the estimated vaporization enthalpy as well as the SVOC content of the OA.

  5. Tropical intercontinental optical measurement network of aerosol, precipitable water and total column ozone

    Science.gov (United States)

    Holben, B. N.; Tanre, D.; Reagan, J. A.; Eck, T. F.; Setzer, A.; Kaufman, Y. A.; Vermote, E.; Vassiliou, G. D.; Lavenu, F.

    1992-01-01

    A new generation of automatic sunphotometers is used to systematically monitor clear sky total column aerosol concentration and optical properties, precipitable water and total column ozone diurnally and annually in West Africa and South America. The instruments are designed to measure direct beam sun, solar aureole and sky radiances in nine narrow spectral bands from the UV to the near infrared on an hourly basis. The instrumentation and the algorithms required to reduce the data for subsequent analysis are described.

  6. Study of Aerosol Liquid Water Content based on Hygroscopicity Measurements at High Relative Humidity in the North China Plain

    Science.gov (United States)

    Bian, Y.; Zhao, C.

    2013-12-01

    Aerosol has significant effects on direct/indirect climate forcing, visibility, tropospheric chemistry and human health. Water can represent an extensive proportion of the mass of aerosol particles, and can also serve as a medium for aqueous-phase reactions in such particulate matter. In this study, a new method is proposed to estimate the aerosol liquid water content at high relative humidity, based on aerosol hygroscopic growth factors, particle number size distribution and relative humidity measured during the Haze in China (HaChi) campaign of July-August, 2009. The aerosol liquid water content estimated by this method is compared to the results calculated by a thermodynamic equilibrium model (ISORROPIA II). The calculation results from these two methods agree well at high relative humidity above 60% with the correlation coefficient of 0.9658. At relative humidity lower than 60%, the thermodynamic equilibrium model underestimates the aerosol liquid water content. The discrepancy is mainly caused by the ISORROPIA II model, which considers only limited chemical species. The mean and maximum value of aerosol liquid water content during July-August, 2009 in the North China Plain reached 1.69×10^{-4}g/m^3 and 9.71×10^{-4}g/m^3, respectively. Aerosol liquid water content is highly related to the relative humidity. There exists a distinct diurnal variation of the aerosol liquid water content, with lower values during daytime and higher ones during night time. The contribution to the aerosol liquid water content from the accumulation mode is dominating among all the aerosol particle modes.

  7. Technical note: Relating functional group measurements to carbon types for improved model-measurement comparisons of organic aerosol composition

    Science.gov (United States)

    Takahama, Satoshi; Ruggeri, Giulia

    2017-04-01

    Functional group (FG) analysis provides a means by which functionalization in organic aerosol can be attributed to the abundances of its underlying molecular structures. However, performing this attribution requires additional, unobserved details about the molecular mixture to provide constraints in the estimation process. We present an approach for conceptualizing FG measurements of organic aerosol in terms of its functionalized carbon atoms. This reformulation facilitates estimation of mass recovery and biases in popular carbon-centric metrics that describe the extent of functionalization (such as oxygen to carbon ratio, organic mass to organic carbon mass ratio, and mean carbon oxidation state) for any given set of molecules and FGs analyzed. Furthermore, this approach allows development of parameterizations to more precisely estimate the organic carbon content from measured FG abundance. We use simulated photooxidation products of α-pinene secondary organic aerosol previously reported by Ruggeri et al. (2016) and FG measurements by Fourier transform infrared (FT-IR) spectroscopy in chamber experiments by Sax et al. (2005) to infer the relationships among molecular composition, FG composition, and metrics of organic aerosol functionalization. We find that for this simulated system, ˜ 80 % of the carbon atoms should be detected by FGs for which calibration models are commonly developed, and ˜ 7 % of the carbon atoms are undetectable by FT-IR analysis because they are not associated with vibrational modes in the infrared. Estimated biases due to undetected carbon fraction for these simulations are used to make adjustments in these carbon-centric metrics such that model-measurement differences are framed in terms of unmeasured heteroatoms (e.g., in hydroperoxide and nitrate groups for the case studied in this demonstration). The formality of this method provides framework for extending FG analysis to not only model-measurement but also instrument

  8. Contact area measurements on structured surfaces

    DEFF Research Database (Denmark)

    Kücükyildiz, Ömer Can; Jensen, Sebastian Hoppe Nesgaard; De Chiffre, Leonardo

    In connection with the use of brass specimens featuring structured surfaces in a tribology test, an algorithm was developed for automatic measurement of the contact area by optical means.......In connection with the use of brass specimens featuring structured surfaces in a tribology test, an algorithm was developed for automatic measurement of the contact area by optical means....

  9. Remote sensing of aerosol and marine parameters in coastal environments: Exploring the advantage of using polarized radiative transfer simulations of the coupled atmosphere-water system to analyze ocean color measurements

    Science.gov (United States)

    Stamnes, K. H.

    2016-02-01

    Simultaneous retrieval of aerosol and surface properties by means of inverse techniques based on a coupled atmosphere-surface radiative transfer model (CRTM) and optimal estimation can yield a considerable improvement in retrieval accuracy based on radiances measured by MERIS, MODIS, and similar instruments compared with traditional methods. There are uniqueness problems associated with photometric remote sensing measurements (like MERIS/MODIS) that ignore polarization effects, and rely on measuring only the radiance. Use of polarization measurements is particularly important for absorbing aerosols over coastal waters as well as over bright targets such as snow-covered and bare sea ice, where it has proved difficult to retrieve aerosol single-scattering albedo from radiance-only spectrometers such as MERIS and MODIS. We use a vector radiative transfer model for the coupled atmosphere-surface system in conjunction with an optimal estimation/Levenberg-Marquardt method to quantify how polarization measurements can be used to overcome the uniqueness problems associated with radiance-only retrieval of aerosol parameters. However, this study also indicates that even for existing instruments like MERIS and MODIS and future instrument like OLCI, that measure radiance-only, use of a polarized CRTM as a forward model in the optimal estimation can lead to significant enhancement of retrieval capabilities, and facilitate simultaneous retrieval of absorbing aerosols and marine parameters in turbid coastal environments.

  10. Remote sensing of aerosols by using polarized, directional and spectral measurements within the A-Train: the PARASOL mission

    Directory of Open Access Journals (Sweden)

    D. Tanré

    2011-07-01

    Full Text Available Instruments dedicated to aerosol monitoring are recently available and the POLDER (POLarization and Directionality of the Earth's Reflectances instrument on board the PARASOL (Polarization & Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar mission is one of them. By measuring the spectral, angular and polarization properties of the radiance at the top of the atmosphere, in coordination with the other A-Train instruments, PARASOL provides the aerosol optical depths (AOD as well as several optical and microphysical aerosol properties. The instrument, the inversion schemes and the list of aerosol parameters are described. Examples of retrieved aerosol parameters are provided as well as innovative approaches and further inversion techniques.

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

    Science.gov (United States)

    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.

  12. Evaluation of NASA Deep Blue/SOAR aerosol retrieval algorithms applied to AVHRR measurements

    Science.gov (United States)

    Sayer, A. M.; Hsu, N. C.; Lee, J.; Carletta, N.; Chen, S.-H.; Smirnov, A.

    2017-09-01

    The Deep Blue (DB) and Satellite Ocean Aerosol Retrieval (SOAR) algorithms have previously been applied to observations from sensors like the Moderate Resolution Imaging Spectroradiometers (MODIS) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) to provide records of midvisible aerosol optical depth (AOD) and related quantities over land and ocean surfaces, respectively. Recently, DB and SOAR have also been applied to Advanced Very High Resolution Radiometer (AVHRR) observations from several platforms (NOAA11, NOAA14, and NOAA18), to demonstrate the potential for extending the DB and SOAR AOD records. This study provides an evaluation of the initial version (V001) of the resulting AVHRR-based AOD data set, including validation against Aerosol Robotic Network (AERONET) and ship-borne observations, and comparison against both other AVHRR AOD records and MODIS/SeaWiFS products at select long-term AERONET sites. Although it is difficult to distil error characteristics into a simple expression, the results suggest that one standard deviation confidence intervals on retrieved AOD of ±(0.03 + 15%) over water and ±(0.05 + 25%) over land represent the typical level of uncertainty, with a tendency toward negative biases in high-AOD conditions, caused by a combination of algorithmic assumptions and sensor calibration issues. Most of the available validation data are for NOAA18 AVHRR, although performance appears to be similar for the NOAA11 and NOAA14 sensors as well.

  13. Aerosol effects in radiation transfer

    International Nuclear Information System (INIS)

    Binenko, V.I.; Harshvardhan, H.

    1993-01-01

    The radiative properties and effects of aerosols are assessed for the following aerosol sources: relatively clean background aerosol, dust storms and dust outbreaks, anthropogenic pollution, and polluted cloud layers. Studies show it is the submicron aerosol fraction that plays a dominant radiative role in the atmosphere. The radiative effect of the aerosol depends not only on its loading but also on the underlying surface albedo and on solar zenith angle. It is only with highly reflecting surfaces such as Arctic ice that aerosols have a warming effect. Radiometric, microphysical, mineral composition, and refractive index measurements are presented for dust and in particular for the Saharan aerosol layer (SAL). Short-wave radiative heating of the atmosphere is caused by the SAL and is due mainly to absorption. However, the SAL does not contribute significantly to the long-wave thermal radiation budget. Field program studies of the radiative effects of aerosols are described. Anthropogenic aerosols deplete the incoming solar radiation. A case field study for a regional Ukrainian center is discussed. The urban aerosol causes a cooling of metropolitan centers, compared with outlying areas, during the day, which is followed by a warming trend at night. In another study, an increase in turbidity by a factor of 3 due to increased industrialization for Mexico City is noted, together with a drop in