Science.gov

Sample records for aerosol dynamics model

  1. The Dynamics of Aerosols: Recent Developments In Regional and Global Modelling

    NASA Astrophysics Data System (ADS)

    Vignati, E.

    An efficient and accurate representation of aerosol size distributions and microphysi- cal processes is required to make physically consistent calculations of the direct and indirect radiative effects of aerosols and their impact on climate. Various modelling approaches have been developed to simulate the dynamical evolu- tion of natural and anthropogenic aerosol populations. Among the components of the particulate phase, sulphate, sea salt, black carbon, organic carbon and dust all play an important role. However their contributions vary from region to region. Modal models, in which the aerosol size distribution is represented by a number of modes, present a computational attractive approach for aerosol dynamic modelling in regional and global models. They can describe external as well as internal mixtures of aerosol particles and the full aerosol dynamics. The accuracy of modal models is however dependent on both the suitability of the lognormal approximation to the size distribution and the extent to which processes can be expressed in terms of distribution parameters. Simultaneously, recent developments have been made to treat many aerosol species in global models using discrete size bins. The detailed description allows a more ac- curate calculation of the aerosol water content, an important parameter required for calculations of aerosol optical properties. However, such a fine size resolution is usu- ally time consuming when used in large scale models, therefore sometimes not all the processes modifying aerosol properties are included. Modest requirements for storage and computations is one of the advantages of moment methods. These techniques have the capability of simultaneously represent the aerosol dynamic processes and transport in large scale models. An overview of recent developments of aerosol modelling in global and regional mod- els will be presented outlining the advantages and disadvantages of the various tech- niques for such large scales.

  2. A one-dimensional sectional aerosol model integrated with mesoscale meteorological data to study marine boundary layer aerosol dynamics

    NASA Astrophysics Data System (ADS)

    Caffrey, Peter F.; Hoppel, William A.; Shi, Jainn J.

    2006-12-01

    The dynamics of aerosols in the marine boundary layer are simulated with a one-dimensional, multicomponent, sectional aerosol model using vertical profiles of turbulence, relative humidity, temperature, vertical velocity, cloud cover, and precipitation provided by 3-D mesoscale meteorological model output. The Naval Research Laboratory's (NRL) sectional aerosol model MARBLES (Fitzgerald et al., 1998a) was adapted to use hourly meteorological input taken from NRL's Coupled Ocean-Atmosphere Prediction System (COAMPS). COAMPS-generated turbulent mixing coefficients and large-scale vertical velocities determine vertical exchange within the marine boundary layer and exchange with the free troposphere. Air mass back trajectories were used to define the air column history along which the meteorology was retrieved for use with the aerosol model. Details on the integration of these models are described here, as well as a description of improvements made to the aerosol model, including transport by large-scale vertical motions (such as subsidence and lifting), a revised sea-salt aerosol source function, and separate tracking of sulfate mass from each of the five sources (free tropospheric, nucleated, condensed from gas phase oxidation products, cloud-processed, and produced from heterogeneous oxidation of S(IV) on sea-salt aerosol). Results from modeling air masses arriving at Oahu, Hawaii, are presented, and the relative contribution of free-tropospheric sulfate particles versus sea-salt aerosol from the surface to CCN concentrations is discussed. Limitations and benefits of the method are presented, as are sensitivity analyses of the effect of large-scale vertical motions versus turbulent mixing.

  3. Coupled turbulence and aerosol dynamics modeling of vehicle exhaust plumes using the CTAG model

    NASA Astrophysics Data System (ADS)

    Wang, Yan Jason; Zhang, K. Max

    2012-11-01

    This paper presents the development and evaluation of an environmental turbulent reacting flow model, the Comprehensive Turbulent Aerosol Dynamics and Gas Chemistry (CTAG) model. CTAG is designed to simulate transport and transformation of multiple air pollutants, e.g., from emission sources to ambient background. For the on-road and near-road applications, CTAG explicitly couples the major turbulent mixing processes, i.e., vehicle-induced turbulence (VIT), road-induced turbulence (RIT) and atmospheric boundary layer turbulence with gas-phase chemistry and aerosol dynamics. CTAG's transport model is referred to as CFD-VIT-RIT. This paper presents the evaluation of the CTAG model in simulating the dynamics of individual plumes in the “tailpipe-to-road” stage, i.e., VIT behind a moving van and aerosol dynamics in the wake of a diesel car by comparing the modeling results against the respective field measurements. Combined with sensitivity studies, we analyze the relative roles of VIT, sulfuric acid induced nucleation, condensation of organic compounds and presence of soot-mode particles in capturing the dynamics of exhaust plumes as well as their implications in vehicle emission controls.

  4. On the characteristics of aerosol indirect effect based on dynamic regimes in global climate models

    NASA Astrophysics Data System (ADS)

    Zhang, Shipeng; Wang, Minghuai; Ghan, Steven J.; Ding, Aijun; Wang, Hailong; Zhang, Kai; Neubauer, David; Lohmann, Ulrike; Ferrachat, Sylvaine; Takeamura, Toshihiko; Gettelman, Andrew; Morrison, Hugh; Lee, Yunha; Shindell, Drew T.; Partridge, Daniel G.; Stier, Philip; Kipling, Zak; Fu, Congbin

    2016-03-01

    Aerosol-cloud interactions continue to constitute a major source of uncertainty for the estimate of climate radiative forcing. The variation of aerosol indirect effects (AIE) in climate models is investigated across different dynamical regimes, determined by monthly mean 500 hPa vertical pressure velocity (ω500), lower-tropospheric stability (LTS) and large-scale surface precipitation rate derived from several global climate models (GCMs), with a focus on liquid water path (LWP) response to cloud condensation nuclei (CCN) concentrations. The LWP sensitivity to aerosol perturbation within dynamic regimes is found to exhibit a large spread among these GCMs. It is in regimes of strong large-scale ascent (ω500 < -25 hPa day-1) and low clouds (stratocumulus and trade wind cumulus) where the models differ most. Shortwave aerosol indirect forcing is also found to differ significantly among different regimes. Shortwave aerosol indirect forcing in ascending regimes is close to that in subsidence regimes, which indicates that regimes with strong large-scale ascent are as important as stratocumulus regimes in studying AIE. It is further shown that shortwave aerosol indirect forcing over regions with high monthly large-scale surface precipitation rate (> 0.1 mm day-1) contributes the most to the total aerosol indirect forcing (from 64 to nearly 100 %). Results show that the uncertainty in AIE is even larger within specific dynamical regimes compared to the uncertainty in its global mean values, pointing to the need to reduce the uncertainty in AIE in different dynamical regimes.

  5. On the characteristics of aerosol indirect effect based on dynamic regimes in global climate models

    SciTech Connect

    Zhang, S.; Wang, Minghuai; Ghan, Steven J.; Ding, A.; Wang, Hailong; Zhang, Kai; Neubauer, David; Lohmann, U.; Ferrachat, S.; Takeamura, Toshihiko; Gettelman, A.; Morrison, H.; Lee, Y. H.; Shindell, D. T.; Partridge, Daniel; Stier, P.; Kipling, Z.; Fu, Congbin

    2016-03-04

    Aerosol-cloud interactions continue to constitute a major source of uncertainty for the estimate of climate radiative forcing. The variation of aerosol indirect effects (AIE) in climate models is investigated across different dynamical regimes, determined by monthly mean 500 hPa vertical pressure velocity (ω500), lower-tropospheric stability (LTS) and large-scale surface precipitation rate derived from several global climate models (GCMs), with a focus on liquid water path (LWP) response to cloud condensation nuclei (CCN) concentrations. The LWP sensitivity to aerosol perturbation within dynamic regimes is found to exhibit a large spread among these GCMs. It is in regimes of strong large-scale ascend (ω500 < -25 hPa/d) and low clouds (stratocumulus and trade wind cumulus) where the models differ most. Shortwave aerosol indirect forcing is also found to differ significantly among different regimes. Shortwave aerosol indirect forcing in ascending regimes is as large as that in stratocumulus regimes, which indicates that regimes with strong large-scale ascend are as important as stratocumulus regimes in studying AIE. 42" It is further shown that shortwave aerosol indirect forcing over regions with high monthly large-scale surface precipitation rate (> 0.1 mm/d) contributes the most to the total aerosol indirect forcing (from 64% to nearly 100%). Results show that the uncertainty in AIE is even larger within specific dynamical regimes than that globally, pointing to the need to reduce the uncertainty in AIE in different dynamical regimes.

  6. Absorbing aerosols over Asia: A Geophysical Fluid Dynamics Laboratory general circulation model sensitivity study of model response to aerosol optical depth and aerosol absorption

    NASA Astrophysics Data System (ADS)

    Randles, C. A.; Ramaswamy, V.

    2008-11-01

    Forcing by absorbing atmospheric black carbon (BC) tends to heat the atmosphere, cool the surface, and reduce the surface latent and sensible heat fluxes. BC aerosol can have a large impact on regional climates and the hydrologic cycle. However, significant uncertainties remain concerning the increases in (1) the total amount of all aerosol species and (2) the amount of aerosol absorption that may have occurred over the 1950-1990 period. Focusing on south and east Asia, the sensitivity of a general circulation model's climate response (with prescribed sea surface temperatures and aerosol distributions) to such changes is investigated by considering a range of both aerosol absorption and aerosol extinction optical depth increases. We include direct and semidirect aerosol effects only. Precipitation changes are less sensitive to changes in aerosol absorption optical depth at lower aerosol loadings. At higher-extinction optical depths, low-level convergence and increases in vertical velocity overcome the stabilizing effects of absorbing aerosols and enhance the monsoonal circulation and precipitation in northwestern India. In contrast, the presence of increases in only scattering aerosols weakens the monsoonal circulation and inhibits precipitation here. Cloud amount changes can enhance or counteract surface solar flux reduction depending on the aerosol loading and absorption, with the changes also influencing the surface temperature and the surface energy balance. The results have implications for aerosol reduction strategies in the future that seek to mitigate air pollution concerns. At higher optical depths, if absorbing aerosol is present, reduction of scattering aerosol alone has a reduced effect on precipitation changes, implying that reductions in BC aerosols should be undertaken at the same time as reductions in sulfate aerosols.

  7. Asian Aerosols: A Geophysical Fluid Dynamics Laboratory general circulation model sensitivity study of model response to aerosol optical depth and aerosol absorption

    NASA Astrophysics Data System (ADS)

    Randles, C. A.; Ramaswamy, V.

    2007-12-01

    Atmospheric absorption by black carbon (BC) aerosol heats the atmosphere while simultaneously cooling the surface and reducing latent and sensible heat fluxes from the land. Recent studies have shown that absorbing BC aerosol can have a large impact on regional climates, including modification of the hydrological cycle. However, significant uncertainties remain with regards to (a) the total amount of all aerosol species and (b) the amount of aerosol absorption. Here we present a GCM sensitivity study focusing on the influences due to total aerosol amount and aerosol absorption in the south and east Asian regions. Six experiments are conducted to test the equilibrium response of the GFDL AM2 GCM (under conditions of prescribed, observed sea surface temperatures) to (i) changes in aerosol absorption caused by changes in BC aerosol amount, and (ii) aerosol extinction optical depth increases corresponding to the year 1990 relative to a control case of 1950. In order to systematically explore the uncertainties in aerosol loading and absorption, the sensitivity experiments are classified into four regimes: low extinction optical depth, low absorption; low extinction optical depth, high absorption; high extinction optical depth, low absorption; and high extinction optical depth, high absorption. Changes in surface temperature and changes in the hydrological cycle are generally insignificant when lower aerosol extinction optical depths are considered. For higher extinction optical depths, the change in the modeled regional circulation relative to the control circulation over south and east Asia is affected by the amount of aerosol absorption and contrasts sharply to the regional circulation change associated with increasing only scattering aerosols. When increasing absorbing aerosols over the region, low-level convergence and increases in vertical velocity overcome the stabilizing effects of the absorbing aerosol and enhance the monsoonal circulation and precipitation rate

  8. SIMULATION OF AEROSOL DYNAMICS: A COMPARATIVE REVIEW OF ALGORITHMS USED IN AIR QUALITY MODELS

    EPA Science Inventory

    A comparative review of algorithms currently used in air quality models to simulate aerosol dynamics is presented. This review addresses coagulation, condensational growth, nucleation, and gas/particle mass transfer. Two major approaches are used in air quality models to repres...

  9. Dynamics and Properties of Global Aerosol using MODIS, AERONET and GOCART Model

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram; Chin, Mian; Reme, Lorraine; Tanre, Didier; Mattoo, Shana

    2002-01-01

    Recently produced daily Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol data for the whole year of 2001 are used to show the concentration and dynamics of aerosol over ocean and large parts of the continents. The data were validated against the Aerosol Robotic Network (AERONET) measurements over land and ocean in a special issue in GRL now in press. Monthly averages and a movie based on the daily data are produced and used to demonstrate the spatial and temporal evolution of aerosol. The MODIS wide spectral range is used to distinguish fine smoke and pollution aerosol from coarse dust and salt. The aerosol is observed above ocean and land. The movie produced from the MODIS data provides a new dimension to aerosol observations by showing the dynamics of the system. For example in February smoke and dust emitted from the Sahel and West Africa is shown to travel to the North-East Atlantic. In April heavy dust and pollution from East Asia is shown to travel to North America. In May-June pollution and dust play a dynamical dance in the Arabian Sea and Bay of Bengal. In Aug-September smoke from South Africa and South America is shown to pulsate in tandem and to periodically to be transported to the otherwise pristine Southern part of the Southern Hemisphere. The MODIS data are compared with the Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation Transport (GOCART) model to test and adjust source and sink strengths in the model and to study the effect of clouds on the representation of the satellite data.

  10. On the characteristics of aerosol indirect effect based on dynamic regimes in global climate models

    DOE PAGES

    Zhang, Shipeng; Wang, Minghuai; Ghan, Steven J.; ...

    2016-03-04

    Aerosol–cloud interactions continue to constitute a major source of uncertainty for the estimate of climate radiative forcing. The variation of aerosol indirect effects (AIE) in climate models is investigated across different dynamical regimes, determined by monthly mean 500 hPa vertical pressure velocity (ω500), lower-tropospheric stability (LTS) and large-scale surface precipitation rate derived from several global climate models (GCMs), with a focus on liquid water path (LWP) response to cloud condensation nuclei (CCN) concentrations. The LWP sensitivity to aerosol perturbation within dynamic regimes is found to exhibit a large spread among these GCMs. It is in regimes of strong large-scale ascentmore » (ω500  <  −25 hPa day−1) and low clouds (stratocumulus and trade wind cumulus) where the models differ most. Shortwave aerosol indirect forcing is also found to differ significantly among different regimes. Shortwave aerosol indirect forcing in ascending regimes is close to that in subsidence regimes, which indicates that regimes with strong large-scale ascent are as important as stratocumulus regimes in studying AIE. It is further shown that shortwave aerosol indirect forcing over regions with high monthly large-scale surface precipitation rate (> 0.1 mm day−1) contributes the most to the total aerosol indirect forcing (from 64 to nearly 100 %). Results show that the uncertainty in AIE is even larger within specific dynamical regimes compared to the uncertainty in its global mean values, pointing to the need to reduce the uncertainty in AIE in different dynamical regimes.« less

  11. Coupling aerosol optics to the chemical transport model MATCH (v5.5.0) and aerosol dynamics module SALSA (v1)

    NASA Astrophysics Data System (ADS)

    Andersson, E.; Kahnert, M.

    2015-12-01

    Modelling aerosol optical properties is a notoriously difficult task due to the particles' complex morphologies and compositions. Yet aerosols and their optical properties are important for Earth system modelling and remote sensing applications. Operational optics models often make drastic and non realistic approximations regarding morphological properties, which can introduce errors. In this study a new aerosol optics model is implemented, in which more realistic morphologies and mixing states are assumed, especially for black carbon aerosols. The model includes both external and internal mixing of all chemical species, it treats externally mixed black carbon as fractal aggregates, and it accounts for inhomogeneous internal mixing of black carbon by use of a novel "core-grey shell" model. Simulated results of radiative fluxes, backscattering coefficients and the Ångström exponent from the new optics model are compared with results from another model simulating particles as externally mixed homogeneous spheres. To gauge the impact on the optical properties from the new optics model, the known and important effects from using aerosol dynamics serves as a reference. The results show that using a more detailed description of particle morphology and mixing states influences the optical properties to the same degree as aerosol dynamics. This is an important finding suggesting that over-simplified optics models coupled to a chemical transport model can introduce considerable errors; this can strongly effect simulations of radiative fluxes in Earth-system models, and it can compromise the use of remote sensing observations of aerosols in model evaluations and chemical data assimilation.

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

    SciTech Connect

    Roldin, P.; Eriksson, A. C.; Nordin, E. Z.; Hermansson, E.; Mogensen, Ditte; Rusanen, A.; Boy, Michael; Swietlicki, E.; Svenningsson, Birgitta; Zelenyuk, Alla; Pagels, J.

    2014-08-11

    We have developed the novel Aerosol Dynamics, gas- and particle- phase chemistry model for laboratory CHAMber studies (ADCHAM). The model combines the detailed gas phase Master Chemical Mechanism version 3.2, an aerosol dynamics and particle phase chemistry module (which considers acid catalysed oligomerization, heterogeneous oxidation reactions in the particle phase and non-ideal interactions between organic compounds, water and inorganic ions) and a kinetic multilayer module for diffusion limited transport of compounds between the gas phase, particle surface and particle bulk phase. In this article we describe and use ADCHAM to study: 1) the mass transfer limited uptake of ammonia (NH3) and formation of organic salts between ammonium (NH4+) and carboxylic acids (RCOOH), 2) the slow and almost particle size independent evaporation of α-pinene secondary organic aerosol (SOA) particles, and 3) the influence of chamber wall effects on the observed SOA formation in smog chambers.

  13. Introducing GMXe: A new global aerosol dynamics and thermodynamics model for climate and air quality studies

    NASA Astrophysics Data System (ADS)

    Pringle, K.; Metzger, S.; Tost, H.; Steil, B.; Lelieveld, J.

    2009-04-01

    The treatment of aerosols in global atmospheric models has advanced significantly in the past decade, but the global aerosol distribution is very complex and simplifications must be made in order to treat aerosols in global models. One common simplification is in the treatment of the partitioning of semi-volatile species (e.g. NH3, HNO3 and H2O) between the gas and the aerosol phases, which is often neglected in models or treated in a simplified manner. The treatment of partitioning is, however, important as it controls the aerosol composition (including the aerosol water concentration) as well as affecting the concentration of both aerosol and gas phase pollutants. This paper introduces the newly developed GMXe aerosol model, which has been developed to investigate gas / aerosol partitioning on a global scale. The model (implemented within the ECHAM5/MESSy Atmospheric Chemistry (EMAC) model) combines an extended version of an established aerosol microphysics model (the M7, Stier et al ACP 2005) with a thermodynamic equilibrium model (EQSAM3, Metzger et al ACP 2008). The resulting model is capable of calculating gas / aerosol partitioning with relatively little additional computational overhead. In this paper we give an overview of the modelling approach used and show various model inter-comparisons, including a detailed comparison of the results of the GMXe and M7 models. We show the effect of including additional aerosol components - such as nitrate aerosol - on the global aerosol distribution and on the behaviour of other aerosol species (e.g. sulphate). The water uptake behaviour of the aerosol is examined, a factor that is important for the aerosol lifetime and also for the aerosol radiative forcing. We examine our results in the context of future emissions scenarios and air quality standards.

  14. Development and application of the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (MADRID)

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Pun, Betty; Vijayaraghavan, Krish; Wu, Shiang-Yuh; Seigneur, Christian; Pandis, Spyros N.; Jacobson, Mark Z.; Nenes, Athanasios; Seinfeld, John H.

    2004-01-01

    A new aerosol model, the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (MADRID) has been developed to simulate atmospheric particulate matter (PM). MADRID and the Carnegie-Mellon University (CMU) bulk aqueous-phase chemistry have been incorporated into the three-dimensional Models-3/Community Multiscale Air Quality model (CMAQ). The resulting model, CMAQ-MADRID, is applied to simulate the August 1987 episode in the Los Angeles basin. Model performance for ozone and PM is consistent with current performance standards. However, organic aerosol was underpredicted at most sites owing to underestimation of primary organic PM emissions and secondary organic aerosol (SOA) formation. Nitrate concentrations were also sometimes underpredicted, mainly owing to overpredictions in vertical mixing, underpredictions in relative humidity, and uncertainties in the emissions of primary pollutants. Including heterogeneous reactions changed hourly O3 by up to 17% and 24-hour average PM2.5, sulfate2.5, and nitrate2.5 concentrations by up to 3, 7, and 19%, respectively. A SOA module with a mechanistic representation provides results that are more consistent with observations than that with an empirical representation. The moving-center scheme for particle growth predicts more accurate size distributions than a typical semi-Lagrangian scheme, which causes an upstream numerical diffusion. A hybrid approach that simulates dynamic mass transfer for coarse PM but assumes equilibrium for fine PM can predict a realistic particle size distribution under most conditions, and the same applies under conditions with insignificant concentrations of reactive coarse particles to a bulk equilibrium approach that allocates transferred mass to different size sections based on condensational growth law. In contrast, a simple bulk equilibrium approach that allocates transferred mass based on a given distribution tends to cause a downstream numerical diffusion in the predicted particle

  15. Global Atmospheric Aerosol Modeling

    NASA Technical Reports Server (NTRS)

    Hendricks, Johannes; Aquila, Valentina; Righi, Mattia

    2012-01-01

    Global aerosol models are used to study the distribution and properties of atmospheric aerosol particles as well as their effects on clouds, atmospheric chemistry, radiation, and climate. The present article provides an overview of the basic concepts of global atmospheric aerosol modeling and shows some examples from a global aerosol simulation. Particular emphasis is placed on the simulation of aerosol particles and their effects within global climate models.

  16. Aerosol Dynamics Laboratory

    SciTech Connect

    Rader, D.J.; Mondy, L.A.

    1990-04-01

    In past five years, Department 1510 has developed a state-of-the-art Aerosol Dynamics Laboratory (ADL). This report documents the current instrumentation and capabilities that exist in this laboratory. The ADL was developed from a variety of sources, with a primary contribution from Department 1510's Independent Research and Development program in aerosol dynamics. Current capabilities of the ADL include: (1) generation of calibration-quality monodisperse particles with diameters between 0.005 to 100 {mu}m, (2) real-time measurement of particle size distributions for particle diameters between 0.01 and 100 {mu}m, (3) in situ, real-time measurement of particle size distributions for particle diameters between 0.3 and 100 {mu}m, and (4) real-time measurement of particle charge distributions for particle diameters between 0.01 and 1.0 {mu}m. 14 refs., 5 figs.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    We have developed the novel Aerosol Dynamics, gas- and particle-phase chemistry model for laboratory CHAMber studies (ADCHAM). The model combines the detailed gas-phase Master Chemical Mechanism version 3.2 (MCMv3.2), an aerosol dynamics and particle-phase chemistry module (which considers acid-catalysed oligomerization, heterogeneous oxidation reactions in the particle phase and non-ideal interactions between organic compounds, water and inorganic ions) and a kinetic multilayer module for diffusion-limited transport of compounds between the gas phase, particle surface and particle bulk phase. In this article we describe and use ADCHAM to study (1) the evaporation of liquid dioctyl phthalate (DOP) particles, (2) the slow and almost particle-size-independent evaporation of α-pinene ozonolysis secondary organic aerosol (SOA) particles, (3) the mass-transfer-limited uptake of ammonia (NH3) and formation of organic salts between ammonium (NH4+) and carboxylic acids (RCOOH), and (4) the influence of chamber wall effects on the observed SOA formation in smog chambers. ADCHAM is able to capture the observed α-pinene SOA mass increase in the presence of NH3(g). Organic salts of ammonium and carboxylic acids predominantly form during the early stage of SOA formation. In the smog chamber experiments, these salts contribute substantially to the initial growth of the homogeneously nucleated particles. The model simulations of evaporating α-pinene SOA particles support the recent experimental findings that these particles have a semi-solid tar-like amorphous-phase state. ADCHAM is able to reproduce the main features of the observed slow evaporation rates if the concentration of low-volatility and viscous oligomerized SOA material at the particle surface increases upon evaporation. The evaporation rate is mainly governed by the reversible decomposition of oligomers back to monomers. Finally, we demonstrate that the mass-transfer-limited uptake of condensable organic compounds

  19. Effect of aerosol subgrid variability on aerosol optical depth and cloud condensation nuclei: implications for global aerosol modelling

    NASA Astrophysics Data System (ADS)

    Weigum, Natalie; Schutgens, Nick; Stier, Philip

    2016-11-01

    A fundamental limitation of grid-based models is their inability to resolve variability on scales smaller than a grid box. Past research has shown that significant aerosol variability exists on scales smaller than these grid boxes, which can lead to discrepancies in simulated aerosol climate effects between high- and low-resolution models. This study investigates the impact of neglecting subgrid variability in present-day global microphysical aerosol models on aerosol optical depth (AOD) and cloud condensation nuclei (CCN). We introduce a novel technique to isolate the effect of aerosol variability from other sources of model variability by varying the resolution of aerosol and trace gas fields while maintaining a constant resolution in the rest of the model. We compare WRF-Chem (Weather and Research Forecast model) runs in which aerosol and gases are simulated at 80 km and again at 10 km resolutions; in both simulations the other model components, such as meteorology and dynamics, are kept at the 10 km baseline resolution. We find that AOD is underestimated by 13 % and CCN is overestimated by 27 % when aerosol and gases are simulated at 80 km resolution compared to 10 km. The processes most affected by neglecting aerosol subgrid variability are gas-phase chemistry and aerosol uptake of water through aerosol-gas equilibrium reactions. The inherent non-linearities in these processes result in large changes in aerosol properties when aerosol and gaseous species are artificially mixed over large spatial scales. These changes in aerosol and gas concentrations are exaggerated by convective transport, which transports these altered concentrations to altitudes where their effect is more pronounced. These results demonstrate that aerosol variability can have a large impact on simulating aerosol climate effects, even when meteorology and dynamics are held constant. Future aerosol model development should focus on accounting for the effect of subgrid variability on these

  20. Aerosol-computational fluid dynamics modeling of ultrafine and black carbon particle emission, dilution, and growth near roadways

    NASA Astrophysics Data System (ADS)

    Huang, L.; Gong, S. L.; Gordon, M.; Liggio, J.; Staebler, R.; Stroud, C. A.; Lu, G.; Mihele, C.; Brook, J. R.; Jia, C. Q.

    2014-12-01

    Many studies have shown that on-road vehicle emissions are the dominant source of ultrafine particles (UFPs; diameter < 100 nm) in urban areas and near-roadway environments. In order to advance our knowledge on the complex interactions and competition among atmospheric dilution, dispersion, and dynamics of UFPs, an aerosol dynamics-computational fluid dynamics (CFD) coupled model is developed and validated against field measurements. A unique approach of applying periodic boundary conditions is proposed to model pollutant dispersion and dynamics in one unified domain from the tailpipe level to the ambient near-road environment. This approach significantly reduces the size of the computational domain, and therefore allows fast simulation of multiple scenarios. The model is validated against measured turbulent kinetic energy (TKE) and horizontal gradient of pollution concentrations perpendicular to a major highway. Through a model sensitivity analysis, the relative importance of individual aerosol dynamical processes on the total particle number concentration (N) and particle number-size distribution (PSD) near a highway is investigated. The results demonstrate that (1) coagulation has a negligible effect on N and particle growth, (2) binary homogeneous nucleation (BHN) of H2SO4-H2O is likely responsible for elevated N closest to the road, and (3) N and particle growth are very sensitive to the condensation of semi-volatile organics (SVOCs), particle dry deposition, and the interaction between these processes. The results also indicate that, without the proper treatment of the atmospheric boundary layer (i.e., its wind profile and turbulence quantities), the nucleation rate would be underestimated by a factor of 5 in the vehicle wake region due to overestimated dilution. Therefore, introducing atmospheric boundary layer (ABL) conditions to activity-based emission models may potentially improve their performance in estimating UFP traffic emissions.

  1. Molecular dynamics simulations of the water adsorption around malonic acid aerosol models.

    PubMed

    Darvas, Maria; Picaud, Sylvain; Jedlovszky, Pál

    2013-07-14

    Water nucleation around a malonic acid aggregate has been studied by means of molecular dynamics simulations in the temperature and pressure range relevant for atmospheric conditions. Systems of different water contents have been considered and a large number of simulations have allowed us to determine the phase diagram of the corresponding binary malonic acid-water systems. Two phases have been evidenced in the phase diagrams corresponding either to water adsorption on a large malonic acid grain at low temperatures, or to the formation of a liquid-like mixed aggregate of the two types of molecules, at higher temperatures. Finally, the comparison between the phase diagrams simulated for malonic acid-water and oxalic acid-water mixtures emphasizes the influence of the O : C ratio on the hydrophilic behavior of the aerosol, and thus on its ability to act as a cloud condensation nucleus, in accordance with recent experimental conclusions.

  2. CADS:Cantera Aerosol Dynamics Simulator.

    SciTech Connect

    Moffat, Harry K.

    2007-07-01

    This manual describes a library for aerosol kinetics and transport, called CADS (Cantera Aerosol Dynamics Simulator), which employs a section-based approach for describing the particle size distributions. CADS is based upon Cantera, a set of C++ libraries and applications that handles gas phase species transport and reactions. The method uses a discontinuous Galerkin formulation to represent the particle distributions within each section and to solve for changes to the aerosol particle distributions due to condensation, coagulation, and nucleation processes. CADS conserves particles, elements, and total enthalpy up to numerical round-off error, in all of its formulations. Both 0-D time dependent and 1-D steady state applications (an opposing-flow flame application) have been developed with CADS, with the initial emphasis on developing fundamental mechanisms for soot formation within fires. This report also describes the 0-D application, TDcads, which models a time-dependent perfectly stirred reactor.

  3. Mesoscale Modeling of the Atmosphere and Aerosols

    DTIC Science & Technology

    2000-09-30

    fires, or the dynamical and topographical forcing is small-scale, as in dust storms . A high-resolution COAMPS is needed to simulate the first stages of...context. However, the tightly coupled application is practical only for dynamically driven aerosols (e.g. dust storms ) or for planned (e.g. known...an imbedded aerosol module for COAMPS for use in the design and evaluation of techniques for coupling off-line transport and dispersion models to

  4. Impact of Mars Water Ice Clouds and Thermal Aerosol Enforcement to the Shortscale Climate Dynamics: Evidence from 1-D Model

    NASA Astrophysics Data System (ADS)

    Rodin, A. V.; Clancy, R. T.; Wilson, R. J.; Richardson, M.; Wolff, M.; Woods, S.

    1997-07-01

    Ground-based observations of Mars atmospheric temperatures, water, and aerosols have suggested that water ice clouds may regulate vertical distribution of dust and, hence, the global radiation balance, with strong seasonal forcing (Clancy et al., 1996). Under specific Martian conditions, condensation of atmospheric water occurs on the dust as Aitken cores, without external sources, dust is efficiently confined below the saturation level of water vapor. This in turn forces the thermal regime and the saturation conditions, particularly around the aphelion northern summer (Clancy et al., 1996). This effect is studied with two 1-D models, a time marching simulation (time step is 4 min), and reduced local steady-state model. Both models treat aerosol particle microphysics, turbulent transport and thermal enforcement interactively, including radiation transfer consistent with derived aerosol vertical and size distributions. Simulations show that in the aphelion season, when clouds are formed below or near 10 km, strong nonlinearity of cloud thermal feedback results in nonuniqueness of a steady-state solution with water vapor saturation level varying by as high as 5-7 km. Such model behavior appears related to observations of rapid variations of a global-average, lower atmosphere temperature over the planet in northern summer (Clancy, 1997). The stability of thermal equilibrium state is controlled by water vapor abundance and the strength of the dust source at the surface. Time marching simulations provide access to the dynamics of seasonal global dust storm relaxation that may play an important role in interannual climate variations on Mars. References: Clancy, R.T., A.W. Grossman, M.J. Wolff, P.B. James, Y.N. Billawala, B.J. Sandor, S.W. Lee, and D.J. Rudy. Water vapor saturation at low altitudes around Mars aphelion: A key to Mars climate? Icarus, 122, 36-62, 1996.

  5. A COMPUTATIONALLY EFFICIENT HYBRID APPROACH FOR DYNAMIC GAS/AEROSOL TRANSFER IN AIR QUALITY MODELS. (R826371C005)

    EPA Science Inventory

    Dynamic mass transfer methods have been developed to better describe the interaction of the aerosol population with semi-volatile species such as nitrate, ammonia, and chloride. Unfortunately, these dynamic methods are computationally expensive. Assumptions are often made to r...

  6. Modeling Aerosol Particle Deposition on a Person Using Computational Fluid Dynamics

    DTIC Science & Technology

    numerical simulations of aerosol particle deposition on the human form. Numerical simulation of a two-phase turbulent impinging jet flow is studied to...validation show that the standard EIM with turbulent tracking tends to over predict the deposition efficiency. Greatly improved results were achieved by

  7. Geophysical Fluid Dynamics Laboratory general circulation model investigation of the indirect radiative effects of anthropogenic sulfate aerosol

    NASA Astrophysics Data System (ADS)

    Ming, Yi; Ramaswamy, V.; Ginoux, Paul A.; Horowitz, Larry W.; Russell, Lynn M.

    2005-11-01

    The Geophysical Fluid Dynamics Laboratory (GFDL) atmosphere general circulation model, with its new cloud scheme, is employed to study the indirect radiative effect of anthropogenic sulfate aerosol during the industrial period. The preindustrial and present-day monthly mean aerosol climatologies are generated from running the Model for Ozone And Related chemical Tracers (MOZART) chemistry-transport model. The respective global annual mean sulfate burdens are 0.22 and 0.81 Tg S. Cloud droplet number concentrations are related to sulfate mass concentrations using an empirical relationship (Boucher and Lohmann, 1995). A distinction is made between "forcing" and flux change at the top of the atmosphere in this study. The simulations, performed with prescribed sea surface temperature, show that the first indirect "forcing" ("Twomey" effect) amounts to an annual mean of -1.5 W m-2, concentrated largely over the oceans in the Northern Hemisphere (NH). The annual mean flux change owing to the response of the model to the first indirect effect is -1.4 W m-2, similar to the annual mean forcing. However, the model's response causes a rearrangement of cloud distribution as well as changes in longwave flux (smaller than solar flux changes). There is thus a differing geographical nature of the radiation field than for the forcing even though the global means are similar. The second indirect effect, which is necessarily an estimate made in terms of the model's response, amounts to -0.9 W m-2, but the statistical significance of the simulated geographical distribution of this effect is relatively low owing to the model's natural variability. Both the first and second effects are approximately linearly additive, giving rise to a combined annual mean flux change of -2.3 W m-2, with the NH responsible for 77% of the total flux change. Statistically significant model responses are obtained for the zonal mean total indirect effect in the entire NH and in the Southern Hemisphere low

  8. Cloud Dynamical Controls on Climate Forcing by Aerosol-Cloud Interactions: New Insights from Observations, High-Resolution Models, and Parameterizations

    NASA Astrophysics Data System (ADS)

    Donner, Leo

    2016-04-01

    At frequently observed, low updraft speeds, cloud droplet and ice crystal number concentrations are controlled mostly by cloud-scale vertical velocities and not aerosol number concentrations. Reducing uncertainty in estimates of climate forcing by aerosol-cloud interactions will require taking account of these thermodynamically limited cloud regimes in global climate models. The scales of the relevant cloud dynamics are often well-below resolved scales in climate and numerical weather prediction models, ranging to tens of meters at large-eddy scale for stratocumulus clouds. Observations of vertical velocities from cloud radars in field programs and at fixed observational sites are providing a basis for evaluating new classes of parameterizations for convective and non-convective clouds that include probability distribution functions (PDFs) for vertical velocity, which can be used to drive physically based representations of droplet and crystal activation. High-resolution cloud models with detailed treatments of aerosol and microphysical processes can also be evaluated using these observations. Vertical velocities in both high-resolution models and parameterizations currently show discrepancies from observations while capturing qualitative features. Improved treatments of microphysical and turbulence processes in high-resolution cloud models hold promise for improving agreement with observations, while a wide range of advances in parameterization are possible paths to improvement for simulating sub-grid vertical velocities and aerosol-cloud interactions.

  9. Aerosol Modeling for the Global Model Initiative

    NASA Technical Reports Server (NTRS)

    Weisenstein, Debra K.; Ko, Malcolm K. W.

    2001-01-01

    The goal of this project is to develop an aerosol module to be used within the framework of the Global Modeling Initiative (GMI). The model development work will be preformed jointly by the University of Michigan and AER, using existing aerosol models at the two institutions as starting points. The GMI aerosol model will be tested, evaluated against observations, and then applied to assessment of the effects of aircraft sulfur emissions as needed by the NASA Subsonic Assessment in 2001. The work includes the following tasks: 1. Implementation of the sulfur cycle within GMI, including sources, sinks, and aqueous conversion of sulfur. Aerosol modules will be added as they are developed and the GMI schedule permits. 2. Addition of aerosol types other than sulfate particles, including dust, soot, organic carbon, and black carbon. 3. Development of new and more efficient parameterizations for treating sulfate aerosol nucleation, condensation, and coagulation among different particle sizes and types.

  10. Parameterization of Aerosol Sinks in Chemical Transport Models

    NASA Technical Reports Server (NTRS)

    Colarco, Peter

    2012-01-01

    The modelers point of view is that the aerosol problem is one of sources, evolution, and sinks. Relative to evolution and sink processes, enormous attention is given to the problem of aerosols sources, whether inventory based (e.g., fossil fuel emissions) or dynamic (e.g., dust, sea salt, biomass burning). On the other hand, aerosol losses in models are a major factor in controlling the aerosol distribution and lifetime. Here we shine some light on how aerosol sinks are treated in modern chemical transport models. We discuss the mechanisms of dry and wet loss processes and the parameterizations for those processes in a single model (GEOS-5). We survey the literature of other modeling studies. We additionally compare the budgets of aerosol losses in several of the ICAP models.

  11. Global modeling of nitrate and ammonium aerosols using EQSAM3

    NASA Astrophysics Data System (ADS)

    Xu, L.; Penner, J. E.

    2009-12-01

    Atmospheric aerosols, particles suspending in air, are important as they affect human health, air quality, and visibility as well as climate. Sulfate, nitrate, ammonium, chloride and sodium are among the most important inorganic aerosol species in the atmosphere. These compounds are hygroscopic and absorb water under almost all ambient environmental conditions. The uptake of water alters the aerosol size, and causes water to become the constituent with the largest atmospheric aerosol mass, especially when the aerosols grow into fog, haze or clouds. Furthermore, several global model studies have demonstrated that rapid increases in nitrogen emissions could produce enough nitrate in aerosols to offset the expected decline in sulfate forcing by 2100 for the extreme IPCC A2 scenario (Bauer et al., 2007). Although nitrate and ammonium were identified as significant anthropogenic sources of aerosols by a number of modeling studies, most global aerosol models still exclude ammonium-nitrate when the direct aerosol forcing is studied. In this study, the computationally efficient equilibrium model, EQSAM3, is incorporated into the UMICH-IMPACT-nitrate model using the hybrid dynamical solution method (Feng and Penner, 2007). The partitioning of nitrate and ammonium along with the corresponding water uptake is evaluated by comparing the model to the EQUISOLVE II method used in Feng and Penner (2007). The model is also evaluated by comparison with the AERONET data base and satellite-based aerosol optical depths.

  12. Introducing the aerosol-climate model MAECHAM5-SAM2

    NASA Astrophysics Data System (ADS)

    Hommel, R.; Timmreck, C.; Graf, H. F.

    2009-04-01

    We are presenting a new global aerosol model MAECHAM5-SAM2 to study the aerosol dynamics in the UTLS under background and volcanic conditions. The microphysical core modul SAM2 treats the formation, the evolution and the transport of stratospheric sulphuric acid aerosol. The aerosol size distribution and the weight percentage of the sulphuric acid solution is calculated dependent on the concentrations of H2SO4 and H2O, their vapor pressures, the atmospheric temperature and pressure. The fixed sectional method is used to resolve an aerosol distribution between 1 nm and 2.6 micron in particle radius. Homogeneous nucleation, condensation and evaporation, coagulation, water-vapor growth, sedimentation and sulphur chemistry are included. The module is applied in the middle-atmosphere MAECHAM5 model, resolving the atmosphere up to 0.01 hPa (~80 km) in 39 layers. It is shown here that MAECHAM5-SAM2 well represents in-situ measured size distributions of stratospheric background aerosol in the northern hemisphere mid-latitudes. Distinct differences can be seen when derived integrated aerosol parameters (surface area, effective radius) are compared with aerosol climatologies based on the SAGE II satellite instrument (derived by the University of Oxford and the NASA AMES laboratory). The bias between the model and the SAGE II data increases as the moment of the aerosol size distribution decreases. Thus the modeled effective radius show the strongest bias, followed by the aerosol surface area density. Correspondingly less biased are the higher moments volume area density and the mass density of the global stratospheric aerosol coverage. This finding supports the key finding No. 2 of the SPARC Assessment of Stratospheric Aerosol Properties (2006), where it was shown that during periods of very low aerosol load in the stratosphere, the consistency between in-situ and satellite measurements, which exist in a volcanically perturbed stratosphere, breaks down and significant

  13. Aerosol activation: parameterised versus explicit calculation for global models

    NASA Astrophysics Data System (ADS)

    Tost, H.; Pringle, K.; Metzger, S.; Lelieveld, J.

    2009-04-01

    A key process in studies of the aerosol indirect effects on clouds is the activation of particles into droplets at 100% relative humidity. To model this process in cloud, meteorological and climate models is a difficult undertaking because of the wide range of scales involved. The chemical composition of the atmospheric aerosol, originating from both air pollution and natural sources, substantially impacts the aerosol water uptake and growth due to its hygroscopicity. In this study a comparison of aerosol activation, using state-of-the-art aerosol activation parameterisations, and explicit activation due to hygroscopic growth is performed.For that purpose we apply the GMXe aerosol model - treating both dynamic and thermodynamic aerosol properties - within the EMAC (ECHAM5/MESSy Atmospheric chemistry, an atmospheric chemistry general circulation) model. This new aerosol model can explicitely calculate the water uptake of aerosols due to hygroscopicity, allowing the growth of aerosol particles into the regimes of cloud droplets in case of sufficient water vapour availability. Global model simulations using both activation schemes will be presented and compared, elucidating the advantages of each approach.

  14. Modelling Aerosol Dispersion in Urban Street Canyons

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

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

  15. Aerosol processing of materials: Aerosol dynamics and microstructure evolution

    NASA Astrophysics Data System (ADS)

    Gurav, Abhijit Shankar

    Spray pyrolysis is an aerosol process commonly used to synthesize a wide variety of materials in powder or film forms including metals, metal oxides and non-oxide ceramics. It is capable of producing high purity, unagglomerated, and micrometer to submicron-size powders, and scale-up has been demonstrated. This dissertation deals with the study of aerosol dynamics during spray pyrolysis of multicomponent systems involving volatile phases/components, and aspects involved with using fuel additives during spray processes to break apart droplets and particles in order to produce powders with smaller sizes. The gas-phase aerosol dynamics and composition size distributions were measured during spray pyrolysis of (Bi, Pb)-Sr-Ca-Cu-O, and Sr-Ru-O and Bi-Ru-O at different temperatures. A differential mobility analyzer (DMA) was used in conjunction with a condensation particle counter (CPC) to monitor the gas-phase particle size distributions, and a Berner-type low-pressure impactor was used to obtain mass size distributions and size-classified samples for chemical analysis. (Bi, Pb)-Sr-Ca-Cu-O powders made at temperatures up to 700sp°C maintained their initial stoichiometry over the whole range of particle sizes monitored, however, those made at 800sp°C and above were heavily depleted in lead in the size range 0.5-5.0 mum. When the reactor temperature was raised from 700 and 800sp°C to 900sp°C, a large number ({˜}10sp7\\ #/cmsp3) of new ultrafine particles were formed from PbO vapor released from the particles and the reactor walls at the beginning of high temperature runs (at 900sp°C). The metal ruthenate systems showed generation of ultrafine particles (<40-50 nm) at the beginning of runs at 800-900sp°C and also as a steady state process at a reactor temperature of 1000sp°C. The methods of aerosol dynamics measurements were also used to monitor the gas-phase particle size distributions during the generation of fullerene (Csb{60}) nano-particles (30 to 50 nm size

  16. Modeling kinetic partitioning of secondary organic aerosol and size distribution dynamics: representing effects of volatility, phase state, and particle-phase reaction

    NASA Astrophysics Data System (ADS)

    Zaveri, R. A.; Easter, R. C.; Shilling, J. E.; Seinfeld, J. H.

    2014-05-01

    This paper describes and evaluates a new framework for modeling kinetic gas-particle partitioning of secondary organic aerosol (SOA) that takes into account diffusion and chemical reaction within the particle phase. The framework uses a combination of (a) an analytical quasi-steady-state treatment for the diffusion-reaction process within the particle phase for fast-reacting organic solutes, and (b) a two-film theory approach for slow- and nonreacting solutes. The framework is amenable for use in regional and global atmospheric models, although it currently awaits specification of the various gas- and particle-phase chemistries and the related physicochemical properties that are important for SOA formation. Here, the new framework is implemented in the computationally efficient Model for Simulating Aerosol Interactions and Chemistry (MOSAIC) to investigate the competitive growth dynamics of the Aitken and accumulation mode particles. Results show that the timescale of SOA partitioning and the associated size distribution dynamics depend on the complex interplay between organic solute volatility, particle-phase bulk diffusivity, and particle-phase reactivity (as exemplified by a pseudo-first-order reaction rate constant), each of which can vary over several orders of magnitude. In general, the timescale of SOA partitioning increases with increase in volatility and decrease in bulk diffusivity and rate constant. At the same time, the shape of the aerosol size distribution displays appreciable narrowing with decrease in volatility and bulk diffusivity and increase in rate constant. A proper representation of these physicochemical processes and parameters is needed in the next generation models to reliably predict not only the total SOA mass, but also its composition- and number-diameter distributions, all of which together determine the overall optical and cloud-nucleating properties.

  17. Aerosol measurement program strategy for global aerosol backscatter model development

    NASA Technical Reports Server (NTRS)

    Bowdle, David A.

    1985-01-01

    The purpose was to propose a balanced program of aerosol backscatter research leading to the development of a global model of aerosol backscatter. Such a model is needed for feasibility studies and systems simulation studies for NASA's prospective satellite-based Doppler lidar wind measurement system. Systems of this kind measure the Doppler shift in the backscatter return from small atmospheric aerosol wind tracers (of order 1 micrometer diameter). The accuracy of the derived local wind estimates and the degree of global wind coverage for such a system are limited by the local availability and by the global scale distribution of natural aerosol particles. The discussions here refer primarily to backscatter model requirements at CO2 wavelengths, which have been selected for most of the Doppler lidar systems studies to date. Model requirements for other potential wavelengths would be similar.

  18. MODELS-3 COMMUNITY MULTISCALE AIR QUALITY (CMAQ) MODEL AEROSOL COMPONENT 1: MODEL DESCRIPTION

    EPA Science Inventory

    The aerosol component of the Community Multiscale Air Quality (CMAQ) model is designed to be an efficient and economical depiction of aerosol dynamics in the atmosphere. The approach taken represents the particle size distribution as the superposition of three lognormal subdis...

  19. Aerosol Behavior Log-Normal Distribution Model.

    SciTech Connect

    GIESEKE, J. A.

    2001-10-22

    HAARM3, an acronym for Heterogeneous Aerosol Agglomeration Revised Model 3, is the third program in the HAARM series developed to predict the time-dependent behavior of radioactive aerosols under postulated LMFBR accident conditions. HAARM3 was developed to include mechanisms of aerosol growth and removal which had not been accounted for in the earlier models. In addition, experimental measurements obtained on sodium oxide aerosols have been incorporated in the code. As in HAARM2, containment gas temperature, pressure, and temperature gradients normal to interior surfaces are permitted to vary with time. The effects of reduced density on sodium oxide agglomerate behavior and of nonspherical shape of particles on aerosol behavior mechanisms are taken into account, and aerosol agglomeration due to turbulent air motion is considered. Also included is a capability to calculate aerosol concentration attenuation factors and to restart problems requiring long computing times.

  20. Global modeling of tropospheric iodine aerosol

    NASA Astrophysics Data System (ADS)

    Sherwen, Tomás. M.; Evans, Mat J.; Spracklen, Dominick V.; Carpenter, Lucy J.; Chance, Rosie; Baker, Alex R.; Schmidt, Johan A.; Breider, Thomas J.

    2016-09-01

    Natural aerosols play a central role in the Earth system. The conversion of dimethyl sulfide to sulfuric acid is the dominant source of oceanic secondary aerosol. Ocean emitted iodine can also produce aerosol. Using a GEOS-Chem model, we present a simulation of iodine aerosol. The simulation compares well with the limited observational data set. Iodine aerosol concentrations are highest in the tropical marine boundary layer (MBL) averaging 5.2 ng (I) m-3 with monthly maximum concentrations of 90 ng (I) m-3. These masses are small compared to sulfate (0.75% of MBL burden, up to 11% regionally) but are more significant compared to dimethyl sulfide sourced sulfate (3% of the MBL burden, up to 101% regionally). In the preindustrial, iodine aerosol makes up 0.88% of the MBL burden sulfate mass and regionally up to 21%. Iodine aerosol may be an important regional mechanism for ocean-atmosphere interaction.

  1. An Aerosol Physical Chemistry Model for the Upper Troposphere

    NASA Technical Reports Server (NTRS)

    Lin, Jin-Sheng

    2001-01-01

    This report is the final report for the Cooperative Agreement NCC2-1000. The tasks outlined in the various proposals are: (1) Development of an aerosol chemistry model; (2) Utilization of satellite measurements of trace gases along with analysis of temperatures and dynamic conditions to understand ice cloud formation, dehydration and sedimentation in the winter polar regions; (3) Comparison of the HALOE and SAGE II time dependencies of the Pinatubo aerosol decay. The publications are attached.

  2. Evaluation of vegetation fire smoke plume dynamics and aerosol load using UV scanning lidar and fire-atmosphere modelling during the Mediterranean Letia 2010 experiment

    NASA Astrophysics Data System (ADS)

    Leroy-Cancellieri, V.; Augustin, P.; Filippi, J. B.; Mari, C.; Fourmentin, M.; Bosseur, F.; Morandini, F.; Delbarre, H.

    2013-08-01

    Vegetation fires emit large amount of gases and aerosols which are detrimental to human health. Smoke exposure near and downwind of fires depends on the fire propagation, the atmospheric circulations and the burnt vegetation. A better knowledge of the interaction between wildfire and atmosphere is a primary requirement to investigate fire smoke and particle transport. The purpose of this paper is to highlight the usefulness of an UV scanning lidar to characterize the fire smoke plume and consequently validate fire-atmosphere model simulations. An instrumented burn was conducted in a Mediterranean area typical of ones frequently concern by wildfire with low dense shrubs. Using Lidar measurements positioned near the experimental site, fire smoke plume was thoroughly characterized by its optical properties, edge and dynamics. These parameters were obtained by combining methods based on lidar inversion technique, wavelet edge detection and a backscatter barycenter technique. The smoke plume displacement was determined using a digital video camera coupled with the Lidar. The simulation was performed using a meso-scale atmospheric model in a large eddy simulation configuration (Meso-NH) coupled to a fire propagation physical model (ForeFire) taking into account the effect of wind, slope and fuel properties. A passive numerical scalar tracer was injected in the model at fire location to mimic the smoke plume. The simulated fire smoke plume width remained within the edge smoke plume obtained from lidar measurements. The maximum smoke injection derived from lidar backscatter coefficients and the simulated passive tracer was around 200 m. The vertical position of the simulated plume barycenter was systematically below the barycenter derived from the lidar backscatter coefficients due to the oversimplified properties of the passive tracer compared to real aerosols particles. Simulated speed and horizontal location of the plume compared well with the observations derived from

  3. Reallocation in modal aerosol models: impacts on predicting aerosol radiative effects

    NASA Astrophysics Data System (ADS)

    Korhola, T.; Kokkola, H.; Korhonen, H.; Partanen, A.-I.; Laaksonen, A.; Lehtinen, K. E. J.; Romakkaniemi, S.

    2013-08-01

    In atmospheric modelling applications the aerosol particle size distribution is commonly represented by modal approach, in which particles in different size ranges are described with log-normal modes within predetermined size ranges. Such method includes numerical reallocation of particles from a mode to another for example during particle growth, leading to potentially artificial changes in the aerosol size distribution. In this study we analysed how this reallocation affects climatologically relevant parameters: cloud droplet number concentration, aerosol-cloud interaction coefficient and light extinction coefficient. We compared these parameters between a modal model with and without reallocation routines, and a high resolution sectional model that was considered as a reference model. We analysed the relative differences of the parameters in different experiments that were designed to cover a wide range of dynamic aerosol processes occurring in the atmosphere. According to our results, limiting the allowed size ranges of the modes and the following numerical remapping of the distribution by reallocation, leads on average to underestimation of cloud droplet number concentration (up to 100%) and overestimation of light extinction (up to 20%). The analysis of aerosol first indirect effect is more complicated as the ACI parameter can be either over- or underestimated by the reallocating model, depending on the conditions. However, for example in the case of atmospheric new particle formation events followed by rapid particle growth, the reallocation can cause around average 10% overestimation of the ACI parameter. Thus it is shown that the reallocation affects the ability of a model to estimate aerosol climate effects accurately, and this should be taken into account when using and developing aerosol models.

  4. Analyses of turbulent flow fields and aerosol dynamics of diesel engine exhaust inside two dilution sampling tunnels using the CTAG model.

    PubMed

    Wang, Yan Jason; Yang, Bo; Lipsky, Eric M; Robinson, Allen L; Zhang, K Max

    2013-01-15

    Experimental results from laboratory emission testing have indicated that particulate emission measurements are sensitive to the dilution process of exhaust using fabricated dilution systems. In this paper, we first categorize the dilution parameters into two groups: (1) aerodynamics (e.g., mixing types, mixing enhancers, dilution ratios, residence time); and (2) mixture properties (e.g., temperature, relative humidity, particle size distributions of both raw exhaust and dilution gas). Then we employ the Comprehensive Turbulent Aerosol Dynamics and Gas Chemistry (CTAG) model to investigate the effects of those parameters on a set of particulate emission measurements comparing two dilution tunnels, i.e., a T-mixing lab dilution tunnel and a portable field dilution tunnel with a type of coaxial mixing. The turbulent flow fields and aerosol dynamics of particles are simulated inside two dilution tunnels. Particle size distributions under various dilution conditions predicted by CTAG are evaluated against the experimental data. It is found that in the area adjacent to the injection of exhaust, turbulence plays a crucial role in mixing the exhaust with the dilution air, and the strength of nucleation dominates the level of particle number concentrations. Further downstream, nucleation terminates and the growth of particles by condensation and coagulation continues. Sensitivity studies reveal that a potential unifying parameter for aerodynamics, i.e., the dilution rate of exhaust, plays an important role in new particle formation. The T-mixing lab tunnel tends to favor the nucleation due to a larger dilution rate of the exhaust than the coaxial mixing field tunnel. Our study indicates that numerical simulation tools can be potentially utilized to develop strategies to reduce the uncertainties associated with dilution samplings of emission sources.

  5. MODELING THE FORMATION OF SECONDARY ORGANIC AEROSOL WITHIN A COMPREHENSIVE AIR QUALITY MODEL SYSTEM

    EPA Science Inventory

    The aerosol component of the CMAQ model is designed to be an efficient and economical depiction of aerosol dynamics in the atmosphere. The approach taken represents the particle size distribution as the superposition of three lognormal subdistributions, called modes. The proces...

  6. Computational fluid dynamics analysis of aerosol deposition in pebble beds

    NASA Astrophysics Data System (ADS)

    Mkhosi, Margaret Msongi

    2007-12-01

    The Pebble Bed Modular Reactor is a high temperature gas cooled reactor which uses helium gas as a coolant. The reactor uses spherical graphite pebbles as fuel. The fuel design is inherently resistant to the release of the radioactive material up to high temperatures; therefore, the plant can withstand a broad spectrum of accidents with limited release of radionuclides to the environment. Despite safety features of the concepts, these reactors still contain large inventories of radioactive materials. The transport of most of the radioactive materials in an accident occurs in the form of aerosol particles. In this dissertation, the limits of applicability of existing computational fluid dynamics code FLUENT to the prediction of aerosol transport have been explored. The code was run using the Reynolds Averaged Navier-Stokes turbulence models to determine the effects of different turbulence models on the prediction of aerosol particle deposition. Analyses were performed for up to three unit cells in the orthorhombic configuration. For low flow conditions representing natural circulation driven flow, the laminar flow model was used and the results were compared with existing experimental data for packed beds. The results compares well with experimental data in the low flow regime. For conditions corresponding to normal operating of the reactor, analyses were performed using the standard k-ɛ turbulence model. From the inertial deposition results, a correlation that can be used to estimate the deposition of aerosol particles within pebble beds given inlet flow conditions has been developed. These results were converted into a dimensionless form as a function of a modified Stokes number. Based on results obtained in the laminar regime and for individual pebbles, the correlation developed for the inertial impaction component of deposition is believed to be credible. The form of the correlation developed also allows these results to be applied to pebble beds of different

  7. Aerosol cloud processing with the global model ECHAM5-HAM-SALSA

    NASA Astrophysics Data System (ADS)

    Bergman, T.; Korhonen, H.; Zubair, M.; Romakkaniemi, S.; Lehtinen, K.; Kokkola, H.

    2012-04-01

    Atmospheric aerosols and their interactions with clouds constitute the largest uncertainty in the radiative forcing of the Earth's atmosphere. Increasing aerosol number concentrations increases the cloud droplet concentration and droplet surface and hence the cloud albedo. This mechanism is called the aerosol indirect effect on climate. Understanding the changes in cloud droplet number concentrations and size by anthropogenic aerosols are the key factors in the study of future climate change. Therefore the aerosols' formation and growth from nanoparticles to cloud condensation nuclei (CCN) must be described accurately. The formation and growth of aerosols are shown to be described more accurately with sectional representations than with bulk (total aerosol mass only), modal (lognormal modes describing mass and number size distribution) or moment (processes tied to different moments of particle number size distribution) approaches. Recently the sectional aerosol models have been implemented to global climate models. However, the resolution of sectional models must be optimised to reduce the computational cost. We have implemented the sectional aerosol model SALSA in ECHAM5-HAM. SALSA describes the aerosol population with 20 size sections. The dynamics are optimised for large scale applications and the model includes an improved moving center sectional method. The particulate mass consists of five compounds: sulphate, organic carbon, black carbon, sea salt and dust. The aerosol processing has been studied extensively and there are many numerical models used to predict CCN number concentrations. However, due to computational limitations many of them are not suitable for utilisation in global climate models. Therefore in most global climate studies on aerosol activation to CCN is examined using cloud activation parameterisations. We study the aerosol cloud processing and its affect on transport of aerosols using Abdul-Razzak-Ghan aerosol cloud activation

  8. Modeling kinetic partitioning of secondary organic aerosol and size distribution dynamics: representing effects of volatility, phase state, and particle-phase reaction

    SciTech Connect

    Zaveri, Rahul A.; Easter, Richard C.; Shilling, John E.; Seinfeld, J. H.

    2014-05-27

    Evidence is mounting that the majority of the climatically active aerosols are produced through the growth of smaller particles via secondary organic aerosol (SOA) formation from gas-to-particle conversion of anthropogenic and biogenic volatile organic compounds (VOCs). The timescale of SOA partitioning and the associated size distribution dynamics are expected to depend on the gas-phase oxidation of the precursor VOCs and their products, volatility of these organic solutes, composition and phase state of the pre-existing particles, and diffusivity and reactivity of the solute within the particle phase. This paper describes a new framework for modeling kinetic gas-particle partitioning of SOA, with an analytical treatment for the diffusion-reaction process within the particle phase. The formulation is amenable for eventual use in regional and global climate models, although it currently awaits implementation of the actual particle-phase reactions that are important for SOA formation. In the present work, the model is applied to investigate the competitive growth dynamics of the Aitken and accumulation mode particles while the Kelvin effect and coagulation are neglected for simplicity. The timescale of SOA partitioning and evolution of number and composition size distributions are evaluated for a range of solute volatilities (C*), particle-phase bulk diffusivities (Db), and particle-phase reactivity, as exemplified by a pseudo-first-order rate constant (kc). Results show that irreversible condensation of non-volatile organic vapors (equivalent to ) produces significant narrowing of the size distribution. At the other extreme, non-reactive partitioning of semi-volatile organic vapors is volume-controlled in which the final (equilibrium) size distribution simply shifts to the right on the diameter axis while its shape remains unchanged. However, appreciable narrowing of the size distribution may occur when the pre-existing particles are highly viscous semi-solids such

  9. Introduction of the aerosol feedback process in the model BOLCHEM

    NASA Astrophysics Data System (ADS)

    Russo, Felicita; Maurizi, Alberto; D'Isidoro, Massimo; Tampieri, Francesco

    2010-05-01

    The effect of aerosols on the climate is still one of the least understood processes in the atmospheric science. The use of models to simulate the interaction between aerosols and climate can help understanding the physical processes that rule this interaction and hopefully predicting the future effects of anthropogenic aerosols on climate. In particular regional models can help study the effect of aerosols on the atmospheric dynamics on a local scale. In the work performed here we studied the feedback of aerosols in the radiative transfer calculation using the regional model BOLCHEM. The coupled meteorology-chemistry model BOLCHEM is based on the BOLAM meteorological model. The BOLAM dynamics is based on hydrostatic primitive equations, with wind components u and v, potential temperature ?, specific humidity q, surface pressure ps, as dependent variables. The vertical coordinate σ is terrain-following with variables distributed on a non-uniformly spaced staggered Lorentz grid. In the standard configuration of the model a collection of climatological aerosol optical depth values for each aerosol species is used for the radiative transfer calculation. In the feedback exercise presented here the aerosol optical depth was calculated starting from the modeled aerosol concentrations using an approximate Mie formulation described by Evans and Fournier (Evans, B.T.N. and G.R. Fournier, Applied Optics, 29, 1990). The calculation was done separately for each species and aerosol size distribution. The refractive indexes for the different species were taken from P. Stier's work (P. Stier et al., Atmos. Chem. Phys., 5, 2005) and the aerosol extinction obtained by Mie calculation were compared with the results reported by OPAC (M. Hess et al., Bull. Am. Met. Soc., 79, 1998). Two model runs, with and without the aerosol feedback, were performed to study the effects of the feedback on meteorological parameters. As a first setup of the model runs we selected a domain over the

  10. Condensing Organic Aerosols in a Microphysical Model

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Tsigaridis, K.; Bauer, S.

    2015-12-01

    The condensation of organic aerosols is represented in a newly developed box-model scheme, where its effect on the growth and composition of particles are examined. We implemented the volatility-basis set (VBS) framework into the aerosol mixing state resolving microphysical scheme Multiconfiguration Aerosol TRacker of mIXing state (MATRIX). This new scheme is unique and advances the representation of organic aerosols in models in that, contrary to the traditional treatment of organic aerosols as non-volatile in most climate models and in the original version of MATRIX, this new scheme treats them as semi-volatile. Such treatment is important because low-volatility organics contribute significantly to the growth of particles. The new scheme includes several classes of semi-volatile organic compounds from the VBS framework that can partition among aerosol populations in MATRIX, thus representing the growth of particles via condensation of low volatility organic vapors. Results from test cases representing Mexico City and a Finish forrest condistions show good representation of the time evolutions of concentration for VBS species in the gas phase and in the condensed particulate phase. Emitted semi-volatile primary organic aerosols evaporate almost completely in the high volatile range, and they condense more efficiently in the low volatility range.

  11. Large-Scale Aerosol Modeling and Analysis

    DTIC Science & Technology

    2007-09-30

    to six days in advance anywhere on the globe. NAAPS and COAMPS are particularly useful for forecasts of dust storms in areas downwind of the large...in FY08. NAAPS forecasts of CONUS dust storms and long-range dust transport to CONUS were further evaluated in collaboration with CSU. These...visibility. The regional model ( COAMPS /Aerosol) became operational during OIF. The global model Navy Aerosol Analysis and Prediction System (NAAPS

  12. Representing Cloud Processing of Aerosol in Numerical Models

    SciTech Connect

    Mechem, D.B.; Kogan, Y.L.

    2005-03-18

    The satellite imagery in Figure 1 provides dramatic examples of how aerosol influences the cloud field. Aerosol from ship exhaust can serve as nucleation centers in otherwise cloud-free regions, forming ship tracks (top image), or can enhance the reflectance/albedo in already cloudy regions. This image is a demonstration of the first indirect effect, in which changes in aerosol modulate cloud droplet radius and concentration, which influences albedo. It is thought that, through the effects it has on precipitation (drizzle), aerosol can also affect the structure and persistence of planetary boundary layer (PBL) clouds. Regions of cellular convection, or open pockets of cloudiness (bottom image) are thought to be remnants of strongly drizzling PBL clouds. Pockets of Open Cloudiness (POCs) (Stevens et al. 2005) or Albrecht's ''rifts'' are low cloud fraction regions characterized by anomalously low aerosol concentrations, implying they result from precipitation. These features may in fact be a demonstration of the second indirect effect. To accurately represent these clouds in numerical models, we have to treat the coupled cloud-aerosol system. We present the following series of mesoscale and large eddy simulation (LES) experiments to evaluate the important aspects of treating the coupled cloud-aerosol problem. 1. Drizzling and nondrizzling simulations demonstrate the effect of drizzle on a mesoscale forecast off the California coast. 2. LES experiments with explicit (bin) microphysics gauge the relative importance of the shape of the aerosol spectrum on the 3D dynamics and cloud structure. 3. Idealized mesoscale model simulations evaluate the relative roles of various processes, sources, and sinks.

  13. MATHEMATICAL MODEL FOR GAS/PARTICLE PARTITIONING OF SECONDARY ORGANIC AEROSOLS. (R824970)

    EPA Science Inventory

    A dynamic model is developed for gas-particle absorptive partitioning of semi-volatile organic aerosols. The model is applied to simulate a pair of m-xylene/NOx outdoor smog chamber experiments. In the presence of an inorganic seed aerosol a threshold ...

  14. A physical model of Titan's aerosols.

    PubMed

    Toon, O B; McKay, C P; Griffith, C A; Turco, R P

    1992-01-01

    Microphysical simulations of Titan's stratospheric haze show that aerosol microphysics is linked to organized dynamical processes. The detached haze layer may be a manifestation of 1 cm sec-1 vertical velocities at altitudes above 300 km. The hemispherical asymmetry in the visible albedo may be caused by 0.05 cm sec-1 vertical velocities at altitudes of 150 to 200 km, we predict contrast reversal beyond 0.6 micrometer. Tomasko and Smith's (1982, Icarus 51, 65-95) model, in which a layer of large particles above 220 km altitude is responsible for the high forward scattering observed by Rages and Pollack (1983, Icarus 55, 50-62), is a natural outcome of the detached haze layer being produced by rising motions if aerosol mass production occurs primarily below the detached haze layer. The aerosol's electrical charge is critical for the particle size and optical depth of the haze. The geometric albedo, particularly in the ultraviolet and near infrared, requires that the particle size be near 0.15 micrometer down to altitudes below 100 km, which is consistent with polarization observations (Tomasko and Smith 1982, West and Smith 1991, Icarus 90, 330-333). Above about 400 km and below about 150 km Yung et al.'s (1984, Astrophys. J. Suppl. Ser. 55, 465-506) diffusion coefficients are too small. Dynamical processes control the haze particles below about 150 km. The relatively large eddy diffusion coefficients in the lower stratosphere result in a vertically extensive region with nonuniform mixing ratios of condensable gases, so that most hydrocarbons may condense very near the tropopause rather than tens of kilometers above it. The optical depths of hydrocarbon clouds are probably less than one, requiring that abundant gases such as ethane condense on a subset of the haze particles to create relatively large, rapidly removed particles. The wavelength dependence of the optical radius is calculated for use in analyzing observations of the geometric albedo. The lower

  15. Aerosol cluster impact and break-up : model and implementation.

    SciTech Connect

    Lechman, Jeremy B.

    2010-10-01

    In this report a model for simulating aerosol cluster impact with rigid walls is presented. The model is based on JKR adhesion theory and is implemented as an enhancement to the granular (DEM) package within the LAMMPS code. The theory behind the model is outlined and preliminary results are shown. Modeling the interactions of small particles is relevant to a number of applications (e.g., soils, powders, colloidal suspensions, etc.). Modeling the behavior of aerosol particles during agglomeration and cluster dynamics upon impact with a wall is of particular interest. In this report we describe preliminary efforts to develop and implement physical models for aerosol particle interactions. Future work will consist of deploying these models to simulate aerosol cluster behavior upon impact with a rigid wall for the purpose of developing relationships for impact speed and probability of stick/bounce/break-up as well as to assess the distribution of cluster sizes if break-up occurs. These relationships will be developed consistent with the need for inputs into system-level codes. Section 2 gives background and details on the physical model as well as implementations issues. Section 3 presents some preliminary results which lead to discussion in Section 4 of future plans.

  16. Evaluation of the modal aerosol model GMXe in the chemistry-climate model GEM-AC

    NASA Astrophysics Data System (ADS)

    Semeniuk, K.; Lupu, A.; Kaminski, J. W.; McConnell, J. C.; O'Neill, N. T.; Tost, H.

    2012-12-01

    We evaluate a modal aerosol model, GMXe, implemented in the atmospheric chemistry-climate model GEM-AC, against global ground-based observations of optical depths and speciated aerosol concentrations. The Global Environmental Multiscale Atmospheric Chemistry model (GEM-AC) is a global, tropospheric-stratospheric chemistry, general circulation model based on the GEM model developed by the Meteorological Service of Canada for operational weather forecasting. Gas-phase chemistry consists in detailed reactions of Ox, NOx, HOx, CO, CH4, NMVOCs, ClOx and BrOx. Tracers are advected using the semi-Lagrangian scheme native to GEM. The vertical transport includes parameterized subgrid scale turbulence and deep convection. Dry deposition is implemented as a flux boundary condition in the vertical diffusion equation. Wet removal comprises both in-cloud and below-cloud scavenging. The Global Modal-aerosol eXtension (GMXe) handles aerosol microphysics and gas-aerosol partitioning. The aerosol size distribution is described by the superposition of 4 hydrophilic and 3 hydrophobic interacting lognormal modes (nucleation, Aitken, accumulation and coarse). Aerosol dynamics includes nucleation, coagulation, and condensation/evaporation. Gas-aerosol partitioning is calculated by the thermodynamic equilibrium model ISORROPIA. The model was run for one year on a 1.5°×1.5° global grid with 73 hybrid levels from the surface to 0.15 hPa. We used aerosol emissions for year 2000 from AeroCom I. The output is compared with aerosol optical depth observations from AERONET, and with measured surface concentrations of sulfate, nitrate and ammonium from CASTNET, EMEP and EANET.

  17. Quantitative respirator fit testing: dynamic pressure versus aerosol measurement.

    PubMed

    Carpenter, D R; Willeke, K

    1988-10-01

    A noninvasive, fast, inexpensive new fit testing method has been invented which relates the slope of the pressure decay inside a respirator during breath-holding to the fit of the respirator on the wearer's face. The dynamic pressure test has been compared with the conventional aerosol test at different leakage levels. The results of this comparison show that the sensitivity of the dynamic pressure test is similar to that of the aerosol test. The pressure test, however, is independent of leak site and probe location and can be performed on respirators before and after their use.

  18. Modelling the optical properties of aerosols in a chemical transport model

    NASA Astrophysics Data System (ADS)

    Andersson, E.; Kahnert, M.

    2015-12-01

    According to the IPCC fifth assessment report (2013), clouds and aerosols still contribute to the largest uncertainty when estimating and interpreting changes to the Earth's energy budget. Therefore, understanding the interaction between radiation and aerosols is both crucial for remote sensing observations and modelling the climate forcing arising from aerosols. Carbon particles are the largest contributor to the aerosol absorption of solar radiation, thereby enhancing the warming of the planet. Modelling the radiative properties of carbon particles is a hard task and involves many uncertainties arising from the difficulties of accounting for the morphologies and heterogeneous chemical composition of the particles. This study aims to compare two ways of modelling the optical properties of aerosols simulated by a chemical transport model. The first method models particle optical properties as homogeneous spheres and are externally mixed. This is a simple model that is particularly easy to use in data assimilation methods, since the optics model is linear. The second method involves a core-shell internal mixture of soot, where sulphate, nitrate, ammonia, organic carbon, sea salt, and water are contained in the shell. However, by contrast to previously used core-shell models, only part of the carbon is concentrated in the core, while the remaining part is homogeneously mixed with the shell. The chemical transport model (CTM) simulations are done regionally over Europe with the Multiple-scale Atmospheric Transport and CHemistry (MATCH) model, developed by the Swedish Meteorological and Hydrological Institute (SMHI). The MATCH model was run with both an aerosol dynamics module, called SALSA, and with a regular "bulk" approach, i.e., a mass transport model without aerosol dynamics. Two events from 2007 are used in the analysis, one with high (22/12-2007) and one with low (22/6-2007) levels of elemental carbon (EC) over Europe. The results of the study help to assess the

  19. Global Aerosol Optical Models and Lookup Tables for the New MODIS Aerosol Retrieval over Land

    NASA Technical Reports Server (NTRS)

    Levy, Robert C.; Remer, Loraine A.; Dubovik, Oleg

    2007-01-01

    Since 2000, MODIS has been deriving aerosol properties over land from MODIS observed spectral reflectance, by matching the observed reflectance with that simulated for selected aerosol optical models, aerosol loadings, wavelengths and geometrical conditions (that are contained in a lookup table or 'LUT'). Validation exercises have showed that MODIS tends to under-predict aerosol optical depth (tau) in cases of large tau (tau greater than 1.0), signaling errors in the assumed aerosol optical properties. Using the climatology of almucantur retrievals from the hundreds of global AERONET sunphotometer sites, we found that three spherical-derived models (describing fine-sized dominated aerosol), and one spheroid-derived model (describing coarse-sized dominated aerosol, presumably dust) generally described the range of observed global aerosol properties. The fine dominated models were separated mainly by their single scattering albedo (omega(sub 0)), ranging from non-absorbing aerosol (omega(sub 0) approx. 0.95) in developed urban/industrial regions, to neutrally absorbing aerosol (omega(sub 0) approx.90) in forest fire burning and developing industrial regions, to absorbing aerosol (omega(sub 0) approx. 0.85) in regions of savanna/grassland burning. We determined the dominant model type in each region and season, to create a 1 deg. x 1 deg. grid of assumed aerosol type. We used vector radiative transfer code to create a new LUT, simulating the four aerosol models, in four MODIS channels. Independent AERONET observations of spectral tau agree with the new models, indicating that the new models are suitable for use by the MODIS aerosol retrieval.

  20. A Simple Model of Global Aerosol Indirect Effects

    SciTech Connect

    Ghan, Steven J.; Smith, Steven J.; Wang, Minghuai; Zhang, Kai; Pringle, K. J.; Carslaw, K. S.; Pierce, Jeffrey; Bauer, Susanne E.; Adams, P. J.

    2013-06-28

    Most estimates of the global mean indirect effect of anthropogenic aerosol on the Earth’s energy balance are from simulations by global models of the aerosol lifecycle coupled with global models of clouds and the hydrologic cycle. Extremely simple models have been developed for integrated assessment models, but lack the flexibility to distinguish between primary and secondary sources of aerosol. Here a simple but more physically-based model expresses the aerosol indirect effect using analytic representations of droplet nucleation, cloud and aerosol vertical structure, and horizontal variability in cloud water and aerosol concentration. Although the simple model is able to produce estimates of aerosol indirect effects that are comparable to those from some global aerosol models using the same global mean aerosol properties, the estimates are found to be sensitive to several uncertain parameters, including the preindustrial cloud condensation nuclei concentration, primary and secondary anthropogenic emissions, the size of the primary particles, the fraction of the secondary anthropogenic emissions that accumulates on the coarse mode, the fraction of the secondary mass that forms new particles, and the sensitivity of liquid water path to droplet number concentration. Aerosol indirect effects are surprisingly linear in emissions. This simple model provides a much stronger physical basis for representing aerosol indirect effects than previous representations in integrated assessment models designed to quickly explore the parameter space of emissions-climate interactions. The model also produces estimates that depend on parameter values in ways that are consistent with results from detailed global aerosol-climate simulation models.

  1. Aerosol Models for the CALIPSO Lidar Inversion Algorithms

    NASA Technical Reports Server (NTRS)

    Omar, Ali H.; Winker, David M.; Won, Jae-Gwang

    2003-01-01

    We use measurements and models to develop aerosol models for use in the inversion algorithms for the Cloud Aerosol Lidar and Imager Pathfinder Spaceborne Observations (CALIPSO). Radiance measurements and inversions of the AErosol RObotic NETwork (AERONET1, 2) are used to group global atmospheric aerosols using optical and microphysical parameters. This study uses more than 105 records of radiance measurements, aerosol size distributions, and complex refractive indices to generate the optical properties of the aerosol at more 200 sites worldwide. These properties together with the radiance measurements are then classified using classical clustering methods to group the sites according to the type of aerosol with the greatest frequency of occurrence at each site. Six significant clusters are identified: desert dust, biomass burning, urban industrial pollution, rural background, marine, and dirty pollution. Three of these are used in the CALIPSO aerosol models to characterize desert dust, biomass burning, and polluted continental aerosols. The CALIPSO aerosol model also uses the coarse mode of desert dust and the fine mode of biomass burning to build a polluted dust model. For marine aerosol, the CALIPSO aerosol model uses measurements from the SEAS experiment 3. In addition to categorizing the aerosol types, the cluster analysis provides all the column optical and microphysical properties for each cluster.

  2. Simulations of Aerosol Microphysics in the NASA GEOS-5 Model

    NASA Technical Reports Server (NTRS)

    Colarco, Peter; Smith; Randles; daSilva

    2010-01-01

    Aerosol-cloud-chemistry interactions have potentially large but uncertain impacts on Earth's climate. One path to addressing these uncertainties is to construct models that incorporate various components of the Earth system and to test these models against data. To that end, we have previously incorporated the Goddard Chemistry, Aerosol, Radiation, and Transport (GOCART) module online in the NASA Goddard Earth Observing System model (GEOS-5). GEOS-5 provides a platform for Earth system modeling, incorporating atmospheric and ocean general circulation models, a land surface model, a data assimilation system, and treatments of atmospheric chemistry and hydrologic cycle. Including GOCART online in this framework has provided a path for interactive aerosol-climate studies; however, GOCART only tracks the mass of aerosols as external mixtures and does not include the detailed treatments of aerosol size distribution and composition (internal mixtures) needed for aerosol-cloud-chemistry-climate studies. To address that need we have incorporated the Community Aerosol and Radiation Model for Atmospheres (CARMA) online in GEOS-5. CARMA is a sectional aerosol-cloud microphysical model, capable of treating both aerosol size and composition explicitly be resolving the aerosol distribution into a variable number of size and composition groupings. Here we present first simulations of dust, sea salt, and smoke aerosols in GEOS-5 as treated by CARMA. These simulations are compared to available aerosol satellite, ground, and aircraft data and as well compared to the simulated distributions in our current GOCART based system.

  3. Cloud-Resolving Model Simulations of Aerosol-Cloud Interactions Triggered by Strong Aerosol Emissions in the Arctic

    NASA Astrophysics Data System (ADS)

    Wang, H.; Kravitz, B.; Rasch, P. J.; Morrison, H.; Solomon, A.

    2014-12-01

    Previous process-oriented modeling studies have highlighted the dependence of effectiveness of cloud brightening by aerosols on cloud regimes in warm marine boundary layer. Cloud microphysical processes in clouds that contain ice, and hence the mechanisms that drive aerosol-cloud interactions, are more complicated than in warm clouds. Interactions between ice particles and liquid drops add additional levels of complexity to aerosol effects. A cloud-resolving model is used to study aerosol-cloud interactions in the Arctic triggered by strong aerosol emissions, through either geoengineering injection or concentrated sources such as shipping and fires. An updated cloud microphysical scheme with prognostic aerosol and cloud particle numbers is employed. Model simulations are performed in pure super-cooled liquid and mixed-phase clouds, separately, with or without an injection of aerosols into either a clean or a more polluted Arctic boundary layer. Vertical mixing and cloud scavenging of particles injected from the surface is still quite efficient in the less turbulent cold environment. Overall, the injection of aerosols into the Arctic boundary layer can delay the collapse of the boundary layer and increase low-cloud albedo. The pure liquid clouds are more susceptible to the increase in aerosol number concentration than the mixed-phase clouds. Rain production processes are more effectively suppressed by aerosol injection, whereas ice precipitation (snow) is affected less; thus the effectiveness of brightening mixed-phase clouds is lower than for liquid-only clouds. Aerosol injection into a clean boundary layer results in a greater cloud albedo increase than injection into a polluted one, consistent with current knowledge about aerosol-cloud interactions. Unlike previous studies investigating warm clouds, the impact of dynamical feedback due to precipitation changes is small. According to these results, which are dependent upon the representation of ice nucleation

  4. Stratospheric dynamics and midlatitude jets under geoengineering with space mirrors and sulfate and titania aerosols

    NASA Astrophysics Data System (ADS)

    Ferraro, A. J.; Charlton-Perez, A. J.; Highwood, E. J.

    2015-01-01

    The impact on the dynamics of the stratosphere of three approaches to geoengineering by solar radiation management is investigated using idealized simulations of a global climate model. The approaches are geoengineering with sulfate aerosols, titania aerosols, and reduction in total solar irradiance (representing mirrors placed in space). If it were possible to use stratospheric aerosols to counterbalance the surface warming produced by a quadrupling of atmospheric carbon dioxide concentrations, tropical lower stratospheric radiative heating would drive a thermal wind response which would intensify the stratospheric polar vortices. In the Northern Hemisphere this intensification results in strong dynamical cooling of the polar stratosphere. Northern Hemisphere stratospheric sudden warming events become rare (one and two in 65 years for sulfate and titania, respectively). The intensification of the polar vortices results in a poleward shift of the tropospheric midlatitude jets in winter. The aerosol radiative heating enhances the tropical upwelling in the lower stratosphere, influencing the strength of the Brewer-Dobson circulation. In contrast, solar dimming does not produce heating of the tropical lower stratosphere, and so there is little intensification of the polar vortex and no enhanced tropical upwelling. The dynamical response to titania aerosol is qualitatively similar to the response to sulfate.

  5. Revisiting Aerosol Effects in Global Climate Models Using an Aerosol Lidar Simulator

    NASA Astrophysics Data System (ADS)

    Ma, P. L.; Chepfer, H.; Winker, D. M.; Ghan, S.; Rasch, P. J.

    2015-12-01

    Aerosol effects are considered a major source of uncertainty in global climate models and the direct and indirect radiative forcings have strong model dependency. These forcings are routinely evaluated (and calibrated) against observations, among them satellite retrievals are greatly used for their near-global coverage. However, the forcings calculated from model output are not directly comparable with those computed from satellite retrievals since sampling and algorithmic differences (such as cloud screening, noise reduction, and retrieval) between models and observations are not accounted for. It is our hypothesis that the conventional model validation procedures for comparing satellite observations and model simulations can mislead model development and introduce biases. Hence, we have developed an aerosol lidar simulator for global climate models that simulates the CALIOP lidar signal at 532nm. The simulator uses the same algorithms as those used to produce the "GCM-oriented CALIPSO Aerosol Product" to (1) objectively sample lidar signal profiles; and (2) derive aerosol fields (e.g., extinction profile, aerosol type, etc) from lidar signals. This allows us to sample and derive aerosol fields in the model and real atmosphere in identical ways. Using the Department of Energy's ACME model simulations, we found that the simulator-retrieved aerosol distribution and aerosol-cloud interactions are significantly different from those computed from conventional approaches, and that the model is much closer to satellite estimates than previously believed.

  6. Analysis of Measurement Requirements for the Aerosol Indirect Effect: A Synthesis of Observations and Modeling

    NASA Astrophysics Data System (ADS)

    Feingold, G.; Previdi, M.; Veron, D. E.

    2003-12-01

    The aerosol indirect effect has been measured for some time now by satellite remote sensors, and more recently by surface-based remote sensors. The indirect effect is often expressed in terms of a relative change in drop size for a relative change in aerosol optical depth or extinction. Here we present some recent results of surface based remote sensing of the indirect effect and assess whether aerosol optical depth or extinction is a suitable proxy for the aerosol affecting drop formation. To do so, we use multiple realizations of a cloud model to investigate the sensitivity of cloud drop effective radius re to aerosol parameters (size distribution and composition) and dynamical parameters (updraft and liquid water content). A breakdown of the individual aerosol terms contributing to drop size change shows that use of aerosol extinction as a proxy for size distribution and composition tends to underestimate the magnitude of the first indirect effect. The use of the aerosol index alleviates this problem somewhat. We show that re is most sensitive to cloud liquid water, a parameter often ignored in indirect effect analyses. The relative importance of the other parameters varies for different conditions but aerosol concentration Na is consistently important. Updraft plays an increasingly important role under high aerosol loadings. Requirements for measuring the indirect effect over polluted continents are shown to be more stringent than those over cleaner, remote oceans. This may influence interpretation of current satellite and surface remote measurements of the indirect effect.

  7. Aerosol Index Dynamics over Athens and Beijing

    NASA Astrophysics Data System (ADS)

    Christodoulakis, J.; Varotsos, C.; Tzanis, C.; Xue, Y.

    2014-11-01

    We present the analysis of monthly mean Aerosol Index (AI) values, over Athens, Greece, and Beijing, China, for the period 1979-2012. The aim of the analysis is the identification of time scaling in the AI time series, by using a data analysis technique that would not be affected by the non-stationarity of the data. The appropriate technique satisfying this criterion is the Detrended Fluctuation Analysis (DF A). For the deseasonalization of time series classic Wiener method was applied filtering out the seasonal - 3 months, semiannual - 6 months and annual - 12 months periods. The data analysis for both Athens and Beijing revealed that the exponents α for both time periods are greater than 0.5 indicating that persistence of the correlations in the fluctuations of the deseasonalized AI values exists for time scales between about 4 months and 3.5 years (for the period 1979-1993) or 4 years (for the period 1996-2012).

  8. Aerosol Index Dynamics over Athens and Beijing

    NASA Astrophysics Data System (ADS)

    Christodoulakis, J.; Varotsos, C.; Tzanis, C.; Xue, Y.

    2014-11-01

    We present the analysis of monthly mean Aerosol Index (AI) values, over Athens, Greece, and Beijing, China, for the period 1979- 2012. The aim of the analysis is the identification of time scaling in the AI time series, by using a data analysis technique that would not be affected by the non-stationarity of the data. The appropriate technique satisfying this criterion is the Detrended Fluctuation Analysis (DFA). For the deseasonalization of time series classic Wiener method was applied filtering out the seasonal - 3 months, semiannual - 6 months and annual - 12 months periods. The data analysis for both Athens and Beijing revealed that the exponents α for both time periods are greater than 0.5 indicating that persistence of the correlations in the fluctuations of the deseasonalized AI values exists for time scales between about 4 months and 3.5 years (for the period 1979-1993) or 4 years (for the period 1996-2012).

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

    NASA Technical Reports Server (NTRS)

    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.

  10. MODIS Satellite Data and GOCART Model Characterization of the Global Aerosol

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram; Chin, Mian; Remer, Lorraine; Tanre, Didier; Lau, William K.-M. (Technical Monitor)

    2003-01-01

    Recently produced daily MODIS aerosol data for the whole year of 2001 are used to show the concentration and dynamics of aerosol over ocean and large parts of the continents. The data were validated against the Aerosol Robotic Network (AERONET) measurements over land and ocean. Monthly averages and a movie based on the daily data are produced and used to demonstrate the spatial and temporal evolution of aerosol. The MODIS wide spectral range is used to distinguish fine smoke and pollution aerosol from coarse dust and salt. The aerosol is observed above ocean and land. The movie produced from the MODIS data provides a new dimension to aerosol observations by showing the dynamics of the system. For example in February smoke and dust emitted from the Sahel and West Africa is shown to travel to the North-East Atlantic. In April heavy dust and pollution from East Asia is shown to travel to North America. In May-June pollution and dust play a dynamical dance in the Arabian Sea and Bay of Bengal. In Aug-September smoke from South Africa and South America is shown to pulsate in tandem and to periodically to be transported to the otherwise pristine Southern part of the Southern Hemisphere. The MODIS data are compared with the GOCART model and used to estimate the first observation based direct anthropogenic radiative forcing of climate by aerosol.

  11. Analytic modeling of aerosol size distributions

    NASA Technical Reports Server (NTRS)

    Deepack, A.; Box, G. P.

    1979-01-01

    Mathematical functions commonly used for representing aerosol size distributions are studied parametrically. Methods for obtaining best fit estimates of the parameters are described. A catalog of graphical plots depicting the parametric behavior of the functions is presented along with procedures for obtaining analytical representations of size distribution data by visual matching of the data with one of the plots. Examples of fitting the same data with equal accuracy by more than one analytic model are also given.

  12. Optimized sparse-particle aerosol representations for modeling cloud-aerosol interactions

    NASA Astrophysics Data System (ADS)

    Fierce, Laura; McGraw, Robert

    2016-04-01

    Sparse representations of atmospheric aerosols are needed for efficient regional- and global-scale chemical transport models. Here we introduce a new framework for representing aerosol distributions, based on the method of moments. Given a set of moment constraints, we show how linear programming can be used to identify collections of sparse particles that approximately maximize distributional entropy. The collections of sparse particles derived from this approach reproduce CCN activity of the exact model aerosol distributions with high accuracy. Additionally, the linear programming techniques described in this study can be used to bound key aerosol properties, such as the number concentration of CCN. Unlike the commonly used sparse representations, such as modal and sectional schemes, the maximum-entropy moment-based approach is not constrained to pre-determined size bins or assumed distribution shapes. This study is a first step toward a new aerosol simulation scheme that will track multivariate aerosol distributions with sufficient computational efficiency for large-scale simulations.

  13. Evaluating Aerosol Process Modules within the Framework of the Aerosol Modeling Testbed

    NASA Astrophysics Data System (ADS)

    Fast, J. D.; Velu, V.; Gustafson, W. I.; Chapman, E.; Easter, R. C.; Shrivastava, M.; Singh, B.

    2012-12-01

    Factors that influence predictions of aerosol direct and indirect forcing, such as aerosol mass, composition, size distribution, hygroscopicity, and optical properties, still contain large uncertainties in both regional and global models. New aerosol treatments are usually implemented into a 3-D atmospheric model and evaluated using a limited number of measurements from a specific case study. Under this modeling paradigm, the performance and computational efficiency of several treatments for a specific aerosol process cannot be adequately quantified because many other processes among various modeling studies (e.g. grid configuration, meteorology, emission rates) are different as well. The scientific community needs to know the advantages and disadvantages of specific aerosol treatments when the meteorology, chemistry, and other aerosol processes are identical in order to reduce the uncertainties associated with aerosols predictions. To address these issues, an Aerosol Modeling Testbed (AMT) has been developed that systematically and objectively evaluates new aerosol treatments for use in regional and global models. The AMT consists of the modular Weather Research and Forecasting (WRF) model, a series testbed cases for which extensive in situ and remote sensing measurements of meteorological, trace gas, and aerosol properties are available, and a suite of tools to evaluate the performance of meteorological, chemical, aerosol process modules. WRF contains various parameterizations of meteorological, chemical, and aerosol processes and includes interactive aerosol-cloud-radiation treatments similar to those employed by climate models. In addition, the physics suite from the Community Atmosphere Model version 5 (CAM5) have also been ported to WRF so that they can be tested at various spatial scales and compared directly with field campaign data and other parameterizations commonly used by the mesoscale modeling community. Data from several campaigns, including the 2006

  14. Mouse Model of Coxiella burnetii Aerosolization

    PubMed Central

    Melenotte, Cléa; Lepidi, Hubert; Nappez, Claude; Bechah, Yassina; Audoly, Gilles; Terras, Jérôme; Raoult, Didier

    2016-01-01

    Coxiella burnetii is mainly transmitted by aerosols and is responsible for multiple-organ lesions. Animal models have shown C. burnetii pathogenicity, but long-term outcomes still need to be clarified. We used a whole-body aerosol inhalation exposure system to mimic the natural route of infection in immunocompetent (BALB/c) and severe combined immunodeficient (SCID) mice. After an initial lung inoculum of 104 C. burnetii cells/lung, the outcome, serological response, hematological disorders, and deep organ lesions were described up to 3 months postinfection. C. burnetii-specific PCR, anti-C. burnetii immunohistochemistry, and fluorescent in situ hybridization (FISH) targeting C. burnetii-specific 16S rRNA completed the detection of the bacterium in the tissues. In BALB/c mice, a thrombocytopenia and lymphopenia were first observed, prior to evidence of C. burnetii replication. In all SCID mouse organs, DNA copies increased to higher levels over time than in BALB/c ones. Clinical signs of discomfort appeared in SCID mice, so follow-up had to be shortened to 2 months in this group. At this stage, all animals presented bone, cervical, and heart lesions. The presence of C. burnetii could be attested in situ for all organs sampled using immunohistochemistry and FISH. This mouse model described C. burnetii Nine Mile strain spread using aerosolization in a way that corroborates the pathogenicity of Q fever described in humans and completes previously published data in mouse models. C. burnetii infection occurring after aerosolization in mice thus seems to be a useful tool to compare the pathogenicity of different strains of C. burnetii. PMID:27160294

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

    PubMed Central

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

    2014-01-01

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

  16. Dynamics of aerosol size during inhalation: hygroscopic growth of commercial nebulizer formulations.

    PubMed

    Haddrell, Allen E; Davies, James F; Miles, Rachael E H; Reid, Jonathan P; Dailey, Lea Ann; Murnane, Darragh

    2014-03-10

    The size of aerosol particles prior to, and during, inhalation influences the site of deposition within the lung. As such, a detailed understanding of the hygroscopic growth of an aerosol during inhalation is necessary to accurately model the deposited dose. In the first part of this study, it is demonstrated that the aerosol produced by a nebulizer, depending on the airflows rates, may experience a (predictable) wide range of relative humidity prior to inhalation and undergo dramatic changes in both size and solute concentration. A series of sensitive single aerosol analysis techniques are then used to make measurements of the relative humidity dependent thermodynamic equilibrium properties of aerosol generated from four common nebulizer formulations. Measurements are also reported of the kinetics of mass transport during the evaporation or condensation of water from the aerosol. Combined, these measurements allow accurate prediction of the temporal response of the aerosol size prior to and during inhalation. Specifically, we compare aerosol composed of pure saline (150 mM sodium chloride solution in ultrapure water) with two commercially available nebulizer products containing relatively low compound doses: Breath®, consisting of a simple salbutamol sulfate solution (5 mg/2.5 mL; 1.7 mM) in saline, and Flixotide® Nebules, consisting of a more complex stabilized fluticasone propionate suspension (0.25 mg/mL; 0.5 mM in saline. A mimic of the commercial product Tobi© (60 mg/mL tobramycin and 2.25 mg/mL NaCl, pH 5.5-6.5) is also studied, which was prepared in house. In all cases, the presence of the pharmaceutical was shown to have a profound effect on the magnitude, and in some cases the rate, of the mass flux of water to and from the aerosol as compared to saline. These findings provide physical chemical evidence supporting observations from human inhalation studies, and suggest that using the growth dynamics of a pure saline aerosol in a lung inhalation model

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

    SciTech Connect

    Richard A. Ferrare; David D. Turner

    2011-09-01

    Project goals: (1) Use the routine surface and airborne measurements at the ARM SGP site, and the routine surface measurements at the NSA site, to continue our evaluations of model aerosol simulations; (2) Determine the degree to which the Raman lidar measurements of water vapor and aerosol scattering and extinction can be used to remotely characterize the aerosol humidification factor; (3) Use the high temporal resolution CARL data to examine how aerosol properties vary near clouds; and (4) Use the high temporal resolution CARL and Atmospheric Emitted Radiance Interferometer (AERI) data to quantify entrainment in optically thin continental cumulus clouds.

  18. MIRAGE: Model Description and Evaluation of Aerosols and Trace Gases

    SciTech Connect

    Easter, Richard C.; Ghan, Steven J.; Zhang, Yang; Saylor, Rick D.; Chapman, Elaine G.; Laulainen, Nels S.; Abdul-Razzak, Hayder; Leung, Lai-Yung R.; Bian, Xindi; Zaveri, Rahul A.

    2004-10-27

    The MIRAGE (Model for Integrated Research on Atmospheric Global Exchanges) modeling system, designed to study the impacts of anthropogenic aerosols on the global environment, is described. MIRAGE consists of a chemical transport model coupled on line with a global climate model. The chemical transport model simulates trace gases, aerosol number, and aerosol chemical component mass [sulfate, MSA, organic matter, black carbon (BC), sea salt, mineral dust] for four aerosol modes (Aitken, accumulation, coarse sea salt, coarse mineral dust) using the modal aerosol dynamics approach. Cloud-phase and interstitial aerosol are predicted separately. The climate model, based on the CCM2, has physically-based treatments of aerosol direct and indirect forcing. Stratiform cloud water and droplet number are simulated using a bulk microphysics parameterization that includes aerosol activation. Aerosol and trace gas species simulated by MIRAGE are presented and evaluated using surface and aircraft measurements. Surface-level SO2 in N. American and European source regions is higher than observed. SO2 above the boundary layer is in better agreement with observations, and surface-level SO2 at marine locations is somewhat lower than observed. Comparison with other models suggests insufficient SO2 dry deposition; increasing the deposition velocity improves simulated SO2. Surface-level sulfate in N. American and European source regions is in good agreement with observations, although the seasonal cycle in Europe is stronger than observed. Surface-level sulfate at high-latitude and marine locations, and sulfate above the boundary layer, are higher than observed. This is attributed primarily to insufficient wet removal; increasing the wet removal improves simulated sulfate at remote locations and aloft. Because of the high sulfate bias, radiative forcing estimates for anthropogenic sulfur in Ghan et al. [2001c] are probably too high. Surface-level DMS is {approx}40% higher than observed

  19. Model describing the dependence of aerosol microstructure on different sea bottom types

    SciTech Connect

    Zielinski, T.; Zielinski, A.

    1996-12-31

    This model describes variations of aerosol size distribution function, aerosol fluxes and their residence times as a function of two different formula for roughness length coefficient including developing roughness and fully developed roughness, diverse sea bottom types with various slopes and different weather conditions with changing wind velocity, direction and duration. This model has been verified experimentally on two types of Baltic Sea bottoms and it allows for the good estimation of aerosol dynamics in the coastal zone provided that wind conditions and the sea bottom type are known.

  20. Multi-sensor cloud and aerosol retrieval simulator and remote sensing from model parameters - Part 2: Aerosols

    NASA Astrophysics Data System (ADS)

    Wind, Galina; da Silva, Arlindo M.; Norris, Peter M.; Platnick, Steven; Mattoo, Shana; Levy, Robert C.

    2016-07-01

    The Multi-sensor Cloud Retrieval Simulator (MCRS) produces a "simulated radiance" product from any high-resolution general circulation model with interactive aerosol as if a specific sensor such as the Moderate Resolution Imaging Spectroradiometer (MODIS) were viewing a combination of the atmospheric column and land-ocean surface at a specific location. Previously the MCRS code only included contributions from atmosphere and clouds in its radiance calculations and did not incorporate properties of aerosols. In this paper we added a new aerosol properties module to the MCRS code that allows users to insert a mixture of up to 15 different aerosol species in any of 36 vertical layers.This new MCRS code is now known as MCARS (Multi-sensor Cloud and Aerosol Retrieval Simulator). Inclusion of an aerosol module into MCARS not only allows for extensive, tightly controlled testing of various aspects of satellite operational cloud and aerosol properties retrieval algorithms, but also provides a platform for comparing cloud and aerosol models against satellite measurements. This kind of two-way platform can improve the efficacy of model parameterizations of measured satellite radiances, allowing the assessment of model skill consistently with the retrieval algorithm. The MCARS code provides dynamic controls for appearance of cloud and aerosol layers. Thereby detailed quantitative studies of the impacts of various atmospheric components can be controlled.In this paper we illustrate the operation of MCARS by deriving simulated radiances from various data field output by the Goddard Earth Observing System version 5 (GEOS-5) model. The model aerosol fields are prepared for translation to simulated radiance using the same model subgrid variability parameterizations as are used for cloud and atmospheric properties profiles, namely the ICA technique. After MCARS computes modeled sensor radiances equivalent to their observed counterparts, these radiances are presented as input to

  1. Multi-Sensor Cloud and Aerosol Retrieval Simulator and Remote Sensing from Model Parameters . Part 2; Aerosols

    NASA Technical Reports Server (NTRS)

    Wind, Galina; Da Silva, Arlindo M.; Norris, Peter M.; Platnick, Steven; Mattoo, Shana; Levy, Robert C.

    2016-01-01

    The Multi-sensor Cloud Retrieval Simulator (MCRS) produces a simulated radiance product from any high-resolution general circulation model with interactive aerosol as if a specific sensor such as the Moderate Resolution Imaging Spectroradiometer (MODIS) were viewing a combination of the atmospheric column and land ocean surface at a specific location. Previously the MCRS code only included contributions from atmosphere and clouds in its radiance calculations and did not incorporate properties of aerosols. In this paper we added a new aerosol properties module to the MCRS code that allows users to insert a mixture of up to 15 different aerosol species in any of 36 vertical layers. This new MCRS code is now known as MCARS (Multi-sensor Cloud and Aerosol Retrieval Simulator). Inclusion of an aerosol module into MCARS not only allows for extensive, tightly controlled testing of various aspects of satellite operational cloud and aerosol properties retrieval algorithms, but also provides a platform for comparing cloud and aerosol models against satellite measurements. This kind of two-way platform can improve the efficacy of model parameterizations of measured satellite radiances, allowing the assessment of model skill consistently with the retrieval algorithm. The MCARS code provides dynamic controls for appearance of cloud and aerosol layers. Thereby detailed quantitative studies of the impacts of various atmospheric components can be controlled. In this paper we illustrate the operation of MCARS by deriving simulated radiances from various data field output by the Goddard Earth Observing System version 5 (GEOS-5) model. The model aerosol fields are prepared for translation to simulated radiance using the same model sub grid variability parameterizations as are used for cloud and atmospheric properties profiles, namely the ICA technique. After MCARS computes modeled sensor radiances equivalent to their observed counterparts, these radiances are presented as input to

  2. Evaluation of atmospheric aerosol and tropospheric ozone effects on global terrestrial ecosystem carbon dynamics

    NASA Astrophysics Data System (ADS)

    Chen, Min

    The increasing human activities have produced large amounts of air pollutants ejected into the atmosphere, in which atmospheric aerosols and tropospheric ozone are considered to be especially important because of their negative impacts on human health and their impacts on global climate through either their direct radiative effect or indirect effect on land-atmosphere CO2 exchange. This dissertation dedicates to quantifying and evaluating the aerosol and tropospheric ozone effects on global terrestrial ecosystem dynamics using a modeling approach. An ecosystem model, the integrated Terrestrial Ecosystem Model (iTem), is developed to simulate biophysical and biogeochemical processes in terrestrial ecosystems. A two-broad-band atmospheric radiative transfer model together with the Moderate-Resolution Imaging Spectroradiometer (MODIS) measured atmospheric parameters are used to well estimate global downward solar radiation and the direct and diffuse components in comparison with observations. The atmospheric radiative transfer modeling framework were used to quantify the aerosol direct radiative effect, showing that aerosol loadings cause 18.7 and 12.8 W m -2 decrease of direct-beam Photosynthetic Active Radiation (PAR) and Near Infrared Radiation (NIR) respectively, and 5.2 and 4.4 W m -2 increase of diffuse PAR and NIR, respectively, leading to a total 21.9 W m-2 decrease of total downward solar radiation over the global land surface during the period of 2003-2010. The results also suggested that the aerosol effect may be overwhelmed by clouds because of the stronger extinction and scattering ability of clouds. Applications of the iTem with solar radiation data and with or without considering the aerosol loadings shows that aerosol loading enhances the terrestrial productions [Gross Primary Production (GPP), Net Primary Production (NPP) and Net Ecosystem Production (NEP)] and carbon emissions through plant respiration (RA) in global terrestrial ecosystems over the

  3. Model for STratospheric Aerosols -MOSTRA : Latest developments

    NASA Astrophysics Data System (ADS)

    Bingen, Christine; Errera, Quentin; Chabrillat, Simon; Vanhellemont, Filip; Fussen, Didier; Mateshvili, Nina; Dekemper, Emmanuel; Loodts, Nicolas

    We present the most recent work related to the development and use of the Model for STrato-spheric Aerosols (MOSTRA). This model is a 3D microphysical/transport model describing the evolution in time and space of the aerosol size distribution described using a set of particle bins. The microphysical module used in the model is based on the PSCBOX model developed by Larsen (2000). The transport module is based on the transport model used in the Belgian Assimilation System of Chemical Observations from Envisat (BASCOE), using a flux-form semi-Lagrangian scheme developed by Lin and Rood (1996). In this presentation, we discuss current challenges and issues, as well as our projects related to MOSTRA for the near future. References: N. Larsen, Polar Stratospheric Clouds, Microphysical and optical models, Scientific Report 00-06, Danish Meteorological Institute, 2000 Lin, S.-J. Rood, R.B., Multidimensional Flux-Form Semi-Lagrangian Transport Schemes, Monthly Weather Review, 124, 2046-2070, 1996.

  4. Development of the RAQM2 aerosol chemical transport model and predictions of the Northeast Asian aerosol mass, size, chemistry, and mixing type

    NASA Astrophysics Data System (ADS)

    Kajino, M.; Inomata, Y.; Sato, K.; Ueda, H.; Han, Z.; An, J.; Katata, G.; Deushi, M.; Maki, T.; Oshima, N.; Kurokawa, J.; Ohara, T.; Takami, A.; Hatakeyama, S.

    2012-12-01

    A new aerosol chemical transport model, the Regional Air Quality Model 2 (RAQM2), was developed to simulate the Asian air quality. We implemented a simple version of a triple-moment modal aerosol dynamics model (MADMS) and achieved a completely dynamic (non-equilibrium) solution of a gas-to-particle mass transfer over a wide range of aerosol diameters from 1 nm to super-μm. To consider a variety of atmospheric aerosol properties, a category approach was utilized in which the aerosols were distributed into four categories: particles in the Aitken mode (ATK), soot-free particles in the accumulation mode (ACM), soot aggregates (AGR), and particles in the coarse mode (COR). The aerosol size distribution in each category is characterized by a single mode. The condensation, evaporation, and Brownian coagulations for each mode were solved dynamically. A regional-scale simulation (Δx = 60 km) was performed for the entire year of 2006 covering the Northeast Asian region. The modeled PM1/bulk ratios of the chemical components were consistent with observations, indicating that the simulated aerosol mixing types were consistent with those in nature. The non-sea-salt SO42- mixed with ATK + ACM was the largest at Hedo in summer, whereas the SOSO42- was substantially mixed with AGR in the cold seasons. Ninety-eight percent of the modeled NO3- was mixed with sea salt at Hedo, whereas 53.7% of the NO3- was mixed with sea salt at Gosan, which is located upwind toward the Asian continent. The condensation of HNO3 onto sea salt particles during transport over the ocean accounts for the difference in the NO3- mixing type at the two sites. Because the aerosol mixing type alters the optical properties and cloud condensation nuclei activity, its accurate prediction and evaluation are indispensable for aerosol-cloud-radiation interaction studies.

  5. Impact of aerosol size representation on modeling aerosol-cloud interactions

    DOE PAGES

    Zhang, Y.; Easter, R. C.; Ghan, S. J.; ...

    2002-11-07

    In this study, we use a 1-D version of a climate-aerosol-chemistry model with both modal and sectional aerosol size representations to evaluate the impact of aerosol size representation on modeling aerosol-cloud interactions in shallow stratiform clouds observed during the 2nd Aerosol Characterization Experiment. Both the modal (with prognostic aerosol number and mass or prognostic aerosol number, surface area and mass, referred to as the Modal-NM and Modal-NSM) and the sectional approaches (with 12 and 36 sections) predict total number and mass for interstitial and activated particles that are generally within several percent of references from a high resolution 108-section approach.more » The modal approach with prognostic aerosol mass but diagnostic number (referred to as the Modal-M) cannot accurately predict the total particle number and surface areas, with deviations from the references ranging from 7-161%. The particle size distributions are sensitive to size representations, with normalized absolute differences of up to 12% and 37% for the 36- and 12-section approaches, and 30%, 39%, and 179% for the Modal-NSM, Modal-NM, and Modal-M, respectively. For the Modal-NSM and Modal-NM, differences from the references are primarily due to the inherent assumptions and limitations of the modal approach. In particular, they cannot resolve the abrupt size transition between the interstitial and activated aerosol fractions. For the 12- and 36-section approaches, differences are largely due to limitations of the parameterized activation for non-log-normal size distributions, plus the coarse resolution for the 12-section case. Differences are larger both with higher aerosol (i.e., less complete activation) and higher SO2 concentrations (i.e., greater modification of the initial aerosol distribution).« less

  6. Impact of aerosol size representation on modeling aerosol-cloud interactions

    SciTech Connect

    Zhang, Y.; Easter, R. C.; Ghan, S. J.; Abdul-Razzak, H.

    2002-11-07

    In this study, we use a 1-D version of a climate-aerosol-chemistry model with both modal and sectional aerosol size representations to evaluate the impact of aerosol size representation on modeling aerosol-cloud interactions in shallow stratiform clouds observed during the 2nd Aerosol Characterization Experiment. Both the modal (with prognostic aerosol number and mass or prognostic aerosol number, surface area and mass, referred to as the Modal-NM and Modal-NSM) and the sectional approaches (with 12 and 36 sections) predict total number and mass for interstitial and activated particles that are generally within several percent of references from a high resolution 108-section approach. The modal approach with prognostic aerosol mass but diagnostic number (referred to as the Modal-M) cannot accurately predict the total particle number and surface areas, with deviations from the references ranging from 7-161%. The particle size distributions are sensitive to size representations, with normalized absolute differences of up to 12% and 37% for the 36- and 12-section approaches, and 30%, 39%, and 179% for the Modal-NSM, Modal-NM, and Modal-M, respectively. For the Modal-NSM and Modal-NM, differences from the references are primarily due to the inherent assumptions and limitations of the modal approach. In particular, they cannot resolve the abrupt size transition between the interstitial and activated aerosol fractions. For the 12- and 36-section approaches, differences are largely due to limitations of the parameterized activation for non-log-normal size distributions, plus the coarse resolution for the 12-section case. Differences are larger both with higher aerosol (i.e., less complete activation) and higher SO2 concentrations (i.e., greater modification of the initial aerosol distribution).

  7. The Influence of the 2006 Indonesian Biomass Burning Aerosols on Tropical Dynamics Studied with the GEOS-5 AGCM

    NASA Technical Reports Server (NTRS)

    Ott, Lesley; Duncan, Bryan; Pawson, Steven; Colarco, Peter; Chin, Mian; Randles, Cynthia; Diehl, Thomas; Nielsen, Eric

    2009-01-01

    The direct and semi-direct effects of aerosols produced by Indonesian biomass burning (BB) during August November 2006 on tropical dynamics have been examined using NASA's Goddard Earth Observing System, Version 5 (GEOS-5) atmospheric general circulation model (AGCM). The AGCM includes CO, which is transported by resolved and sub-grid processes and subject to a linearized chemical loss rate. Simulations were driven by two sets of aerosol forcing fields calculated offline, one that included Indonesian BB aerosol emissions and one that did not. In order to separate the influence of the aerosols from internal model variability, the means of two ten-member ensembles were compared. Diabatic heating from BB aerosols increased temperatures over Indonesia between 150 and 400 hPa. The higher temperatures resulted in strong increases in upward grid-scale vertical motion, which increased water vapor and CO over Indonesia. In October, the largest increases in water vapor were found in the mid-troposphere (25%) while the largest increases in CO occurred just below the tropopause (80 ppbv or 50%). Diabatic heating from the Indonesian BB aerosols caused CO to increase by 9% throughout the tropical tropopause layer in November and 5% in the lower stratosphere in December. The results demonstrate that aerosol heating plays an important role in the transport of BB pollution and troposphere-to-stratosphere transport. Changes in vertical motion and cloudiness induced by aerosol heating can also alter the transport and phase of water vapor in the upper troposphere/lower stratosphere.

  8. Modeling and analysis of aerosol processes in an interactive chemistry general circulation model

    NASA Astrophysics Data System (ADS)

    Verma, Sunita; Boucher, O.; Reddy, M. S.; Upadhyaya, H. C.; Le van, P.; Binkowski, F. S.; Sharma, O. P.

    2007-02-01

    An "online" aerosol dynamics and chemistry module is included in the Laboratoire de Météorologie Dynamique general circulation model (LMDZ), so that the chemical species are advected at each dynamical time step and evolve through chemical and physical processes that have been parameterized consistently with the meteorology. These processes include anthropogenic and biogenic emissions, over 50 gas/aqueous phase chemical reactions, transport due to advection, vertical diffusion and convection, dry deposition and wet scavenging. We have introduced a size-resolved representation of aerosols which undergo various processes such as coagulation, nucleation and dry and wet scavenging. The model considers 16 prognostic tracers: water vapor, liquid water, dimethyl sulfide (DMS), hydrogen sulfide (H2S), dimethyl sulphoxide (DMSO), methanesulphonic acid (MSA), sulfur dioxide (SO2), nitrogen oxides (NOX), carbon monoxide (CO), nitric acid (HNO3), ozone (O3), hydrogen peroxide (H2O2), sulfate mass and number for Aitken and accumulation modes. The scheme accounts for two-way interactions between tropospheric chemistry and aerosols. The oxidants and chemical species fields that represent the sulfate aerosol formation are evolved interactively with the model dynamics. A detailed description on the coupled climate-chemistry interactive module is presented with the evaluation of chemical species in winter and summer seasons. Aqueous phase reactions in cloud accounted for 71% of sulfate production rate, while only 45% of the sulfate burden in the troposphere is derived from in-cloud oxidation.

  9. Climate implications of carbonaceous aerosols: An aerosol microphysical study using the GISS/MATRIX climate model

    NASA Astrophysics Data System (ADS)

    Bauer, S. E.

    2009-12-01

    Recently, attention has been drawn towards black carbon aerosols as a likely short-term climate warming mitigation candidate. However the global and regional impacts of the direct and especially the indirect aerosol forcing effects are highly uncertain, due to the complex nature of aerosol evolution and its climate interactions. Black carbon is directly released as particle into the atmosphere, but then interacts with other gases and particles through condensation and coagulation processes leading to further aerosol growth, aging and internal mixing. Those aerosol characteristics determine their role in direct and indirect aerosol forcing, as their chemical composition and size distribution determine their optical properties and cloud activation potential. A new detailed aerosol microphysical scheme, MATRIX, embedded within the global GISS modelE climate model includes the above processes that determine the lifecycle and climate impact of aerosols. This study presents a quantitative assessment and an uncertainty estimate of the impact of microphysical processes involving black carbon and its optical properties on aerosol cloud activation and radiative forcing. We calculate an anthropogenic net radiative forcing of -0.46 W/m2, relative to emission changes between 1750 and 2000. This study finds the direct and indirect aerosol effect to be very sensitivity towards the size distribution of the emitted black and organic particles. The total net radiative forcing can vary between -0.26 to -0.47 W/m2. The models radiation transfer scheme reacts even more sensitive to black carbon core shell structure assumptions. Assuming that sulfates, nitrates and secondary organics can lead to a coating shell around a black carbon core can turn the overall net radiative forcing from a negative to a positive number. In the light of these sensitivities, black carbon mitigation experiments can show no to up to very significant impact to slower global warming.

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

    SciTech Connect

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

    2011-07-06

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

  11. Aerosol Radiative Forcing and Weather Forecasts in the ECMWF Model

    NASA Astrophysics Data System (ADS)

    Bozzo, A.; Benedetti, A.; Rodwell, M. J.; Bechtold, P.; Remy, S.

    2015-12-01

    Aerosols play an important role in the energy balance of the Earth system via direct scattering and absorpiton of short-wave and long-wave radiation and indirect interaction with clouds. Diabatic heating or cooling by aerosols can also modify the vertical stability of the atmosphere and influence weather pattern with potential impact on the skill of global weather prediction models. The Copernicus Atmosphere Monitoring Service (CAMS) provides operational daily analysis and forecast of aerosol optical depth (AOD) for five aerosol species using a prognostic model which is part of the Integrated Forecasting System of the European Centre for Medium-Range Weather Forecasts (ECMWF-IFS). The aerosol component was developed during the research project Monitoring Atmospheric Composition and Climate (MACC). Aerosols can have a large impact on the weather forecasts in case of large aerosol concentrations as found during dust storms or strong pollution events. However, due to its computational burden, prognostic aerosols are not yet feasible in the ECMWF operational weather forecasts, and monthly-mean climatological fields are used instead. We revised the aerosol climatology used in the operational ECMWF IFS with one derived from the MACC reanalysis. We analyse the impact of changes in the aerosol radiative effect on the mean model climate and in medium-range weather forecasts, also in comparison with prognostic aerosol fields. The new climatology differs from the previous one by Tegen et al 1997, both in the spatial distribution of the total AOD and the optical properties of each aerosol species. The radiative impact of these changes affects the model mean bias at various spatial and temporal scales. On one hand we report small impacts on measures of large-scale forecast skill but on the other hand details of the regional distribution of aerosol concentration have a large local impact. This is the case for the northern Indian Ocean where the radiative impact of the mineral

  12. ModelE2-TOMAS development and evaluation using aerosol optical depths, mass and number concentrations

    NASA Astrophysics Data System (ADS)

    Lee, Y. H.; Adams, P. J.; Shindell, D. T.

    2014-09-01

    The TwO-Moment Aerosol Sectional microphysics model (TOMAS) has been integrated into the state-of-the-art general circulation model, GISS ModelE2. TOMAS has the flexibility to select a size resolution as well as the lower size cutoff. A computationally efficient version of TOMAS is used here, which has 15 size bins covering 3 nm to 10 μm aerosol dry diameter. For each bin, it simulates the total aerosol number concentration and mass concentrations of sulphate, pure elementary carbon (hydrophobic), mixed elemental carbon (hydrophilic), hydrophobic organic matter, hydrophilic organic matter, sea salt, mineral dust, ammonium, and aerosol-associated water. This paper provides a detailed description of the ModelE2-TOMAS model and evaluates the model against various observations including aerosol precursor gas concentrations, aerosol mass and number concentrations, and aerosol optical depths. Additionally, global budgets in ModelE2-TOMAS are compared with those of other global aerosol models, and the TOMAS model is compared to the default aerosol model in ModelE2, which is a bulk aerosol model. Overall, the ModelE2-TOMAS predictions are within the range of other global aerosol model predictions, and the model has a reasonable agreement with observations of sulphur species and other aerosol components as well as aerosol optical depth. However, ModelE2-TOMAS (as well as the bulk aerosol model) cannot capture the observed vertical distribution of sulphur dioxide over the Pacific Ocean possibly due to overly strong convective transport. The TOMAS model successfully captures observed aerosol number concentrations and cloud condensation nuclei concentrations. Anthropogenic aerosol burdens in the bulk aerosol model running in the same host model as TOMAS (ModelE2) differ by a few percent to a factor of 2 regionally, mainly due to differences in aerosol processes including deposition, cloud processing, and emission parameterizations. Larger differences are found for naturally

  13. Modeling global organic aerosol formation and growth

    NASA Astrophysics Data System (ADS)

    Tsimpidi, Alexandra; Karydis, Vlasios; Pandis, Spyros; Lelieveld, Jos

    2014-05-01

    A computationally efficient framework for the description of organic aerosol (OA)-gas partitioning and chemical aging has been developed and implemented into the EMAC atmospheric chemistry-climate model. This model simulates the formation of primary (POA) and secondary organic aerosols (SOA) from semi-volatile (SVOC), intermediate-volatile (IVOC) and volatile organic compounds (VOC). POA are divided in two groups with saturation concentrations at 298 K 0.1, 10, 1000, 100000 µg m-3: OA from fossil fuel combustion and biomass burning. The first 2 surrogate species from each group represent the SVOC while the other surrogate species represent the IVOC. Photochemical reactions that change the volatility of the organics in the gas phase are taken into account. The oxidation products from each group of precursors (SVOC, IVOC, and VOC) are lumped into an additional set of oxidized surrogate species (S-SOA, I-SOA, and V-SOA, respectively) in order to track their source of origin. This model is used to i) estimate the relative contributions of SOA and POA to total OA, ii) determine how SOA concentrations are affected by biogenic and anthropogenic emissions, and iii) evaluate the effect of photochemical aging and long-range transport on OA budget over specific regions.

  14. Modeling the Relationships Between Aerosol Properties and the Direct and Indirect Effects of Aerosols on Climate

    NASA Technical Reports Server (NTRS)

    Toon, Owen B.

    1994-01-01

    Aerosols may affect climate directly by scattering and absorbing visible and infrared energy, They may also affect climate indirectly by modifying the properties of clouds through microphysical processes, and by altering abundances of radiatively important gases through heterogeneous chemistry. Researchers understand which aerosol properties control the direct effect of aerosols on the radiation budget. Unfortunately, despite an abundance of data on certain types of aerosols, much work remains to be done to determine the values of these properties. For instance we have little idea about the global distribution, seasonal variation, or interannual variability of the aerosol optical depth. Also we do not know the visible light absorption properties of tropical aerosols which may contain much debris from slash and burn agriculture. A positive correlation between aerosol concentrations and albedos of marine stratus clouds is observed, and the causative microphysics is understood. However, models suggest that it is difficult to produce new particles in the marine boundary layer. Some modelers have suggested that the particles in the marine boundary layer may originate in the free troposphere and be transported into the boundary layer. Others argue that the aerosols are created in the marine boundary layer. There are no data linking aerosol concentration and cirrus cloud albedo, and models suggest cirrus properties may not be very sensitive to aerosol abundance. There is clear evidence of a radiatively significant change in the global lower stratospheric ozone abundance during the past few decades. These changes are caused by heterogeneous chemical reactions occurring on the surfaces of particles. The rates of these reactions depend upon the chemical composition of the particles. Although rapid advances in understanding heterogeneous chemistry have been made, much remains to be done.

  15. Aerosols

    Atmospheric Science Data Center

    2013-04-17

    ... article title:  Aerosols over Central and Eastern Europe     View Larger Image ... last weeks of March 2003, widespread aerosol pollution over Europe was detected by several satellite-borne instruments. The Multi-angle ...

  16. The Long-Standing Dynamical Impacts of Climate Engineering following the Injection of Stratospheric Sulphate Aerosol

    NASA Astrophysics Data System (ADS)

    Osprey, S. M.; Gray, L. J.; Haywood, J.; Jones, A.

    2014-12-01

    Discussions of our response to climate change invariably involve issues of adaptation and mitigation. The former presupposes unavoidable climate consequences and recognises a need to lessen their impact. The latter attempts to lessen the effects of increasing greenhouse gases (GHG) by (1) reducing GHG emission, (2) creating CO2 sinks (e.g. carbon sequestration) or by blocking the effects of solar radiation (solar radiation management - SRM). The SPICE project was set up to investigate the feasibility of implementing a practical method of SRM using the stratospheric injection of aerosols. SPICE remit includes: engineering design for the delivery of stratospheric aerosol, laboratory measurements for characterising the properties of optimal aerosol, and modelling studies looking into the parameterisation and impact of stratospheric aerosols within a state-of-the-art global climate model. The project has also pressed for the need for governance of climate engineering research. We describe idealised experiments investigating the environmental impact following sulphate aerosol injection into the tropical low-mid stratosphere. We compare a geo-engineering scenario (GeoMIP G4), which includes a constant injection rate of SO2 (5Tg/year) beginning at 2020, against a control simulation of increasing greenhouse gas forcing, as outlined by the CMIP5 RCP4.5 scenario. We use the well-documented stratosphere-resolving Hadley Centre model, which has been employed in previous CMIP5 and climate engineering studies. We examine for high-latitude impacts following tropical aerosol injection, and in particular the Holton-Tan effect observed in the wintertime extratropical stratosphere. These dynamical sensitivities provide an important link, bridging tropical stratosphere forcing with the near-surface response often seen at high latitudes.

  17. A Simple Model of Global Aerosol Indirect Effects

    NASA Technical Reports Server (NTRS)

    Ghan, Steven J.; Smith, Steven J.; Wang, Minghuai; Zhang, Kai; Pringle, Kirsty; Carslaw, Kenneth; Pierce, Jeffrey; Bauer, Susanne; Adams, Peter

    2013-01-01

    Most estimates of the global mean indirect effect of anthropogenic aerosol on the Earth's energy balance are from simulations by global models of the aerosol lifecycle coupled with global models of clouds and the hydrologic cycle. Extremely simple models have been developed for integrated assessment models, but lack the flexibility to distinguish between primary and secondary sources of aerosol. Here a simple but more physically based model expresses the aerosol indirect effect (AIE) using analytic representations of cloud and aerosol distributions and processes. Although the simple model is able to produce estimates of AIEs that are comparable to those from some global aerosol models using the same global mean aerosol properties, the estimates by the simple model are sensitive to preindustrial cloud condensation nuclei concentration, preindustrial accumulation mode radius, width of the accumulation mode, size of primary particles, cloud thickness, primary and secondary anthropogenic emissions, the fraction of the secondary anthropogenic emissions that accumulates on the coarse mode, the fraction of the secondary mass that forms new particles, and the sensitivity of liquid water path to droplet number concentration. Estimates of present-day AIEs as low as 5 W/sq m and as high as 0.3 W/sq m are obtained for plausible sets of parameter values. Estimates are surprisingly linear in emissions. The estimates depend on parameter values in ways that are consistent with results from detailed global aerosol-climate simulation models, which adds to understanding of the dependence on AIE uncertainty on uncertainty in parameter values.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. MATRIX-VBS Condensing Organic Aerosols in an Aerosol Microphysics Model

    NASA Technical Reports Server (NTRS)

    Gao, Chloe Y.; Tsigaridis, Konstas; Bauer, Susanne E.

    2015-01-01

    The condensation of organic aerosols is represented in a newly developed box-model scheme, where its effect on the growth and composition of particles are examined. We implemented the volatility-basis set (VBS) framework into the aerosol mixing state resolving microphysical scheme Multiconfiguration Aerosol TRacker of mIXing state (MATRIX). This new scheme is unique and advances the representation of organic aerosols in models in that, contrary to the traditional treatment of organic aerosols as non-volatile in most climate models and in the original version of MATRIX, this new scheme treats them as semi-volatile. Such treatment is important because low-volatility organics contribute significantly to the growth of particles. The new scheme includes several classes of semi-volatile organic compounds from the VBS framework that can partition among aerosol populations in MATRIX, thus representing the growth of particles via condensation of low volatility organic vapors. Results from test cases representing Mexico City and a Finish forrest condistions show good representation of the time evolutions of concentration for VBS species in the gas phase and in the condensed particulate phase. Emitted semi-volatile primary organic aerosols evaporate almost completely in the high volatile range, and they condense more efficiently in the low volatility range.

  20. Explicit Simulation of Aerosol Physics in a Cloud-Resolving Model: Aerosol Transport and Processing in the Free Troposphere.

    NASA Astrophysics Data System (ADS)

    Ekman, Annica M. L.; Wang, Chien; Ström, Johan; Krejci, Radovan

    2006-02-01

    Large concentrations of small aerosols have been previously observed in the vicinity of anvils of convective clouds. A 3D cloud-resolving model (CRM) including an explicit size-resolving aerosol module has been used to examine the origin of these aerosols. Five different types of aerosols are considered: nucleation mode sulfate aerosols (here defined by 0 d 5.84 nm), Aitken mode sulfate aerosols (here defined by 5.84 nm d 31.0 nm), accumulation mode sulfate aerosols (here defined by d 31.0 nm), mixed aerosols, and black carbon aerosols.The model results suggest that approximately 10% of the initial boundary layer number concentration of Aitken mode aerosols and black carbon aerosols are present at the top of the convective cloud as the cloud reaches its decaying state. The simulated average number concentration of Aitken mode aerosols in the cloud anvil (1.6 × 104 cm-3) is in the same order of magnitude as observations. Thus, the model results strongly suggest that vertical convective transport, particularly during the active period of the convection, is responsible for a major part of the appearance of high concentrations of small aerosols (corresponding to the Aitken mode in the model) observed in the vicinity of cloud anvils.There is some formation of new aerosols within the cloud, but the formation is small. Nucleation mode aerosols are also efficiently scavenged through impaction scavenging by precipitation. Accumulation mode and mixed mode aerosols are efficiently scavenged through nucleation scavenging and their concentrations in the cloud anvil are either very low (mixed mode) or practically zero (accumulation mode).In addition to the 3D CRM, a box model, including important features of the aerosol module of the 3D model, has been used to study the formation of new aerosols after the cloud has evaporated. The possibility of these aerosols to grow to suitable cloud condensation or ice nuclei size is also examined. Concentrations of nucleation mode aerosols

  1. Reallocation in modal aerosol models: impacts on predicting aerosol radiative effects

    NASA Astrophysics Data System (ADS)

    Korhola, T.; Kokkola, H.; Korhonen, H.; Partanen, A.-I.; Laaksonen, A.; Lehtinen, K. E. J.; Romakkaniemi, S.

    2014-01-01

    Atmospheric models often represent the aerosol particle size distribution with a modal approach, in which particles are described with log-normal modes within predetermined size ranges. This approach reallocates particles numerically from one mode to another for example during particle growth, potentially leading to artificial changes in the aerosol size distribution. In this study we analysed how the modal reallocation affects climate-relevant variables: cloud droplet number concentration (CDNC), aerosol-cloud interaction parameter (ACI) and light extinction coefficient (qext). The ACI parameter gives the response of CDNC to a change in total aerosol number concentration. We compared these variables between a modal model (with and without reallocation routines) and a high resolution sectional model, which was considered a reference model. We analysed the relative differences in the chosen variables in four experiments designed to assess the influence of atmospheric aerosol processes. We find that limiting the allowed size ranges of the modes, and subsequent remapping of the distribution, leads almost always to an underestimation of cloud droplet number concentrations (by up to 100%) and an overestimation of light extinction (by up to 20%). On the other hand, the aerosol-cloud interaction parameter can be either over- or underestimated by the reallocating model, depending on the conditions. For example, in the case of atmospheric new particle formation events followed by rapid particle growth, the reallocation can cause on average a 10% overestimation of the ACI parameter. Thus it is shown that the reallocation affects the ability of a model to estimate aerosol climate effects accurately, and this should be taken into account when using and developing aerosol models.

  2. American Association for Aerosol Research (AAAR) `95

    SciTech Connect

    1995-12-31

    The Fourteenth annual meeting of the American Association for Aerosol Research was held October 9-13, 1995 at Westin William Penn Hotel in Pittsburgh, PA. This volume contains the abstracts of the papers and poster sessions presented at this meeting, grouped by the session in which they were presented as follows: Radiation Effects; Aerosol Deposition; Collision Simulations and Microphysical Behavior; Filtration Theory and Measurements; Materials Synthesis; Radioactive and Nuclear Aerosols; Aerosol Formation, Thermodynamic Properties, and Behavior; Particle Contamination Issues in the Computer Industry; Pharmaceutical Aerosol Technology; Modeling Global/Regional Aerosols; Visibility; Respiratory Deposition; Biomass and Biogenic Aerosols; Aerosol Dynamics; Atmospheric Aerosols.

  3. The Aerosol Modeling Testbed: A community tool to objectively evaluate aerosol process modules

    SciTech Connect

    Fast, Jerome D.; Gustafson, William I.; Chapman, Elaine G.; Easter, Richard C.; Rishel, Jeremy P.; Zaveri, Rahul A.; Grell, Georg; Barth, Mary

    2011-03-02

    This study describes a new modeling paradigm that significantly advances how the third activity is conducted while also fully exploiting data and findings from the first two activities. The Aerosol Modeling Testbed (AMT) is a computational framework for the atmospheric sciences community that streamlines the process of testing and evaluating aerosol process modules over a wide range of spatial and temporal scales. The AMT consists of a fully-coupled meteorology-chemistry-aerosol model, and a suite of tools to evaluate the performance of aerosol process modules via comparison with a wide range of field measurements. The philosophy of the AMT is to systematically and objectively evaluate aerosol process modules over local to regional spatial scales that are compatible with most field campaigns measurement strategies. The performance of new treatments can then be quantified and compared to existing treatments before they are incorporated into regional and global climate models. Since the AMT is a community tool, it also provides a means of enhancing collaboration and coordination among aerosol modelers.

  4. The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-Resolving Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Li, Xiaowen; Khain, Alexander; Matsui, Toshihisa; Lang, Stephen; Simpson, Joanne

    2008-01-01

    Aerosols and especially their effect on clouds are one of the key components of the climate system and the hydrological cycle [Ramanathan et al., 2001]. Yet, the aerosol effect on clouds remains largely unknown and the processes involved not well understood. A recent report published by the National Academy of Science states "The greatest uncertainty about the aerosol climate forcing - indeed, the largest of all the uncertainties about global climate forcing - is probably the indirect effect of aerosols on clouds [NRC, 2001]." The aerosol effect on clouds is often categorized into the traditional "first indirect (i.e., Twomey)" effect on the cloud droplet sizes for a constant liquid water path [Twomey, 1977] and the "semi-direct" effect on cloud coverage [e.g., Ackerman et al ., 2001]." Enhanced aerosol concentrations can also suppress warm rain processes by producing a narrow droplet spectrum that inhibits collision and coalescence processes [e.g., Squires and Twomey, 1961; Warner and Twomey, 1967; Warner, 1968; Rosenfeld, 19991. The aerosol effect on precipitation processes, also known as the second type of aerosol indirect effect [Albrecht, 1989], is even more complex, especially for mixed-phase convective clouds. Table 1 summarizes the key observational studies identifying the microphysical properties, cloud characteristics, thermodynamics and dynamics associated with cloud systems from high-aerosol continental environments. For example, atmospheric aerosol concentrations can influence cloud droplet size distributions, warm-rain process, cold-rain process, cloud-top height, the depth of the mixed phase region, and occurrence of lightning. In addition, high aerosol concentrations in urban environments could affect precipitation variability by providing an enhanced source of cloud condensation nuclei (CCN). Hypotheses have been developed to explain the effect of urban regions on convection and precipitation [van den Heever and Cotton, 2007 and Shepherd, 2005

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

    SciTech Connect

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

    1999-06-07

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

  6. 3D direct impacts of urban aerosols on dynamics during the CAPITOUL field experiment

    NASA Astrophysics Data System (ADS)

    Aouizerats, B.; Tulet, P.; Gomes, L.

    2012-12-01

    Evaluating the radiative impacts of aerosol particles is of great interest for understanding atmospheric physics and processes feedbacks. To respond to such objectives, the online fully coupled model Meso-NH is applied to a real case during a two-day Intensive Observation Period (IOP) of the CAPITOUL campaign. The aerosol optical properties are computed from the chemical composition and the size distribution of the particle population, and are compared to observations and analysed at local and regional scales. The differences between two simulations are then studied in order to isolate the direct radiative impacts of aerosols on dynamics. Results show that the aerosol particles generate a forcing on shortwave flux by a decrease of the amount reaching the surface up to 30 Wm-2. The resulting feedbacks lead to a cooling up to 0.6 K on the 2-meter temperature over the city of Toulouse and over the larger 125 km by 125 km area around Toulouse. This cooling is also modeled along the whole boundary layer, leading to a decrease of the boundary layer height up to -50 m during the afternoon and a decrease of the vertical velocities with an average of -3 %.

  7. Modeling aerosol growth by aqueous chemistry in nonprecipitating stratiform cloud

    SciTech Connect

    Ovchinnikov, Mikhail; Easter, Richard C.

    2010-07-29

    A new microphysics module based on a two-dimensional (2D) joint size distribution function representing both interstitial and cloud particles is developed and applied to studying aerosol processing in non-precipitating stratocumulus clouds. The module is implemented in a three-dimensional dynamical framework of a large-eddy simulation (LES) model and in a trajectory ensemble model (TEM). Both models are used to study the modification of sulfate aerosol by the activation - aqueous chemistry - resuspension cycle in shallow marine stratocumulus clouds. The effect of particle mixing and different size-distribution representations on modeled aerosol processing are studied in a comparison of the LES and TEM simulations with the identical microphysics treatment exposes and a comparison of TEM simulations with a 2D fixed and moving bin microphysics. Particle mixing which is represented in LES and neglected in the TEM leads to the mean relative per particle dry mass change in the TEM simulations being about 30% lower than in analogous subsample of LES domain. Particles in the final LES spectrum are mixed in from different “parcels”, some of which have experienced longer in-cloud residence times than the TEM parcels, all of which originated in the subcloud layer, have. The mean relative per particle dry mass change differs by 14% between TEM simulations with fixed and moving bin microphysics. Finally, the TEM model with the moving bin microphysics is used to evaluate assumptions about liquid water mass partitioning among activated cloud condensation nuclei (CCN) of different dry sizes. These assumptions are used in large-scale models to map the bulk aqueous chemistry sulfate production, which is largely proportional to the liquid water mass, to the changes in aerosol size distribution. It is shown that the commonly used assumptions that the droplet mass is independent of CCN size or that the droplet mass is proportional to the CCN size to the third power do not perform

  8. Impact of the modal aerosol scheme GLOMAP-mode on aerosol forcing in the Hadley Centre Global Environmental Model

    NASA Astrophysics Data System (ADS)

    Bellouin, N.; Mann, G. W.; Woodhouse, M. T.; Johnson, C.; Carslaw, K. S.; Dalvi, M.

    2013-03-01

    The Hadley Centre Global Environmental Model (HadGEM) includes two aerosol schemes: the Coupled Large-scale Aerosol Simulator for Studies in Climate (CLASSIC), and the new Global Model of Aerosol Processes (GLOMAP-mode). GLOMAP-mode is a modal aerosol microphysics scheme that simulates not only aerosol mass but also aerosol number, represents internally-mixed particles, and includes aerosol microphysical processes such as nucleation. In this study, both schemes provide hindcast simulations of natural and anthropogenic aerosol species for the period 2000-2006. HadGEM simulations of the aerosol optical depth using GLOMAP-mode compare better than CLASSIC against a data-assimilated aerosol re-analysis and aerosol ground-based observations. Because of differences in wet deposition rates, GLOMAP-mode sulphate aerosol residence time is two days longer than CLASSIC sulphate aerosols, whereas black carbon residence time is much shorter. As a result, CLASSIC underestimates aerosol optical depths in continental regions of the Northern Hemisphere and likely overestimates absorption in remote regions. Aerosol direct and first indirect radiative forcings are computed from simulations of aerosols with emissions for the year 1850 and 2000. In 1850, GLOMAP-mode predicts lower aerosol optical depths and higher cloud droplet number concentrations than CLASSIC. Consequently, simulated clouds are much less susceptible to natural and anthropogenic aerosol changes when the microphysical scheme is used. In particular, the response of cloud condensation nuclei to an increase in dimethyl sulphide emissions becomes a factor of four smaller. The combined effect of different 1850 baselines, residence times, and abilities to affect cloud droplet number, leads to substantial differences in the aerosol forcings simulated by the two schemes. GLOMAP-mode finds a present-day direct aerosol forcing of -0.49 W m-2 on a global average, 72% stronger than the corresponding forcing from CLASSIC. This

  9. Analysis of Atmospheric Aerosol Data Sets and Application of Radiative Transfer Models to Compute Aerosol Effects

    NASA Technical Reports Server (NTRS)

    Schmid, Beat; Bergstrom, Robert W.; Redemann, Jens

    2002-01-01

    This report is the final report for "Analysis of Atmospheric Aerosol Data Sets and Application of Radiative Transfer Models to Compute Aerosol Effects". It is a bibliographic compilation of 29 peer-reviewed publications (published, in press or submitted) produced under this Cooperative Agreement and 30 first-authored conference presentations. The tasks outlined in the various proposals are listed below with a brief comment as to the research performed. Copies of title/abstract pages of peer-reviewed publications are attached.

  10. A general circulation model (GCM) parameterization of Pinatubo aerosols

    SciTech Connect

    Lacis, A.A.; Carlson, B.E.; Mishchenko, M.I.

    1996-04-01

    The June 1991 volcanic eruption of Mt. Pinatubo is the largest and best documented global climate forcing experiment in recorded history. The time development and geographical dispersion of the aerosol has been closely monitored and sampled. Based on preliminary estimates of the Pinatubo aerosol loading, general circulation model predictions of the impact on global climate have been made.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  12. Impact of the modal aerosol scheme GLOMAP-mode on aerosol forcing in the Hadley Centre Global Environmental Model

    NASA Astrophysics Data System (ADS)

    Bellouin, N.; Mann, G. W.; Woodhouse, M. T.; Johnson, C.; Carslaw, K. S.; Dalvi, M.

    2012-08-01

    The Hadley Centre Global Environmental Model (HadGEM) includes two aerosol schemes: the Coupled Large-scale Aerosol Simulator for Studies in Climate (CLASSIC), and the new Global Model of Aerosol Processes (GLOMAP-mode). GLOMAP-mode is a modal aerosol microphysics scheme that simulates not only aerosol mass but also aerosol number, represents internally-mixed particles, and includes aerosol microphysical processes such as nucleation. In this study, both schemes provide hindcast simulations of natural and anthropogenic aerosol species for the period 2000-2006. HadGEM simulations using GLOMAP-mode compare better than CLASSIC against a data-assimilated aerosol re-analysis and aerosol ground-based observations. GLOMAP-mode sulphate aerosol residence time is two days longer than CLASSIC sulphate aerosols, whereas black carbon residence time is much shorter. As a result, CLASSIC underestimates aerosol optical depths in continental regions of the Northern Hemisphere and likely overestimates absorption in remote regions. Aerosol direct and first indirect radiative forcings are computed from simulations of aerosols with emissions for the year 1850 and 2000. In 1850, GLOMAP-mode predicts lower aerosol optical depths and higher cloud droplet number concentrations than CLASSIC. Consequently, simulated clouds are much less susceptible to natural and anthropogenic aerosol changes when the microphysical scheme is used. In particular, the response of cloud condensation nuclei to an increase in dimethyl sulphide emissions becomes a factor of four smaller. The combined effect of different 1850 baselines, residence times, and cloud susceptibilities, leads to substantial differences in the aerosol forcings simulated by the two schemes. GLOMAP-mode finds a present-day direct aerosol forcing of -0.49 W m-2 on a global average, 72% stronger than the corresponding forcing from CLASSIC. This difference is compensated by changes in first indirect aerosol forcing: the forcing of -1.17 W m-2

  13. First Evaluation of the CCAM Aerosol Simulation over Africa: Implications for Regional Climate Modeling

    NASA Astrophysics Data System (ADS)

    Horowitz, H.; Garland, R. M.; Thatcher, M. J.; Naidoo, M.; van der Merwe, J.; Landman, W.; Engelbrecht, F.

    2015-12-01

    An accurate representation of African aerosols in climate models is needed to understand the regional and global radiative forcing and climate impacts of aerosols, at present and under future climate change. However, aerosol simulations in regional climate models for Africa have not been well-tested. Africa contains the largest single source of biomass-burning smoke aerosols and dust globally. Although aerosols are short-lived relative to greenhouse gases, black carbon in particular is estimated to be second only to carbon dioxide in contributing to warming on a global scale. Moreover, Saharan dust is exported great distances over the Atlantic Ocean, affecting nutrient transport to regions like the Amazon rainforest, which can further impact climate. Biomass burning aerosols are also exported from Africa, westward from Angola over the Atlantic Ocean and off the southeastern coast of South Africa to the Indian Ocean. Here, we perform the first extensive quantitative evaluation of the Conformal-Cubic Atmospheric Model (CCAM) aerosol simulation against monitored data, focusing on aerosol optical depth (AOD) observations over Africa. We analyze historical regional simulations for 1999 - 2012 from CCAM consistent with the experimental design of CORDEX at 50 km global horizontal resolution, through the dynamical downscaling of ERA-Interim data reanalysis data, with the CMIP5 emissions inventory (RCP8.5 scenario). CCAM has a prognostic aerosol scheme for organic carbon, black carbon, sulfate, and dust, and non-prognostic sea salt. The CCAM AOD at 550nm was compared to AOD (observed at 440nm, adjusted to 550nm with the Ångström exponent) from long-term AERONET stations across Africa. Sites strongly impacted by dust and biomass burning and with long continuous records were prioritized. In general, the model captures the monthly trends of the AERONET data. This presentation provides a basis for understanding how well aerosol particles are represented over Africa in

  14. Computational fluid dynamics (CFD) simulations of dilute fluid-particle flows in aerosol concentrators

    NASA Astrophysics Data System (ADS)

    Hari, Sridhar

    2003-07-01

    In this study, commercially available Computational Fluid Dynamics (CFD) software, CFX-4.4 has been used for the simulations of aerosol transport through various aerosol-sampling devices. Aerosol transport was modeled as a classical dilute and dispersed two-phase flow problem. Eulerian-Lagrangian framework was adopted wherein the fluid was treated as the continuous phase and aerosol as the dispersed phase, with a one-way coupling between the phases. Initially, performance of the particle transport algorithm implemented in the code was validated against available experimental and numerical data in the literature. Code predictions were found to be in good agreement against experimental data and previous numerical predictions. As a next step, the code was used as a tool to optimize the performance of a virtual impactor prototype. Suggestions on critical geometrical details available in the literature, for a virtual impactor, were numerically investigated on the prototype and the optimum set of parameters was determined. Performance curves were generated for the optimized design at various operating conditions. A computational model of the Linear Slot Virtual Impactor (LSVI) fabricated based on the optimization study, was constructed using the worst-case values of the measured geometrical parameters, with offsets in the horizontal and vertical planes. Simulations were performed on this model for the LSVI operating conditions. Behavior of various sized particles inside the impactor was illustrated with the corresponding particle tracks. Fair agreement was obtained between code predictions and experimental results. Important information on the virtual impactor performance, not known earlier, or, not reported in the literature in the past, obtained from this study, is presented. In the final part of this study, simulations on aerosol deposition in turbulent pipe flow were performed. Code predictions were found to be completely uncorrelated to experimental data. The

  15. Role of Clouds, Aerosols, and Aerosol-Cloud Interaction in 20th Century Simulations with GISS ModelE2

    NASA Technical Reports Server (NTRS)

    Nazarenko, Larissa; Rind, David; Bauer, Susanne; Del Genio, Anthony

    2015-01-01

    We use the new version of NASA Goddard Institute for Space Studies (GISS) climate model, modelE2 with 2º by 2.5º horizontal resolution and 40 vertical layers, with the model top at 0.1 hPa [Schmidt et al., 2014]. We use two different treatments of the atmospheric composition and aerosol indirect effect: (1) TCAD(I) version has fully interactive Tracers of Aerosols and Chemistry in both the troposphere and stratosphere. This model predicts total aerosol number and mass concentrations [Shindell et al., 2013]; (2) TCAM is the aerosol microphysics and chemistry model based on the quadrature methods of moments [Bauer et al., 2008]. Both TCADI and TCAM models include the first indirect effect of aerosols on clouds [Menon et al., 2010]; the TCAD model includes only the direct aerosol effect. We consider the results of the TCAD, TCADI and TCAM models coupled to "Russell ocean model" [Russell et al., 1995], E2-R. We examine the climate response for the "historical period" that include the natural and anthropogenic forcings for 1850 to 2012. The effect of clouds, their feedbacks, as well as the aerosol-cloud interactions are assessed for the transient climate change.

  16. Aerosols and clouds in chemical transport models and climate models.

    SciTech Connect

    Lohmann,U.; Schwartz, S. E.

    2008-03-02

    Clouds exert major influences on both shortwave and longwave radiation as well as on the hydrological cycle. Accurate representation of clouds in climate models is a major unsolved problem because of high sensitivity of radiation and hydrology to cloud properties and processes, incomplete understanding of these processes, and the wide range of length scales over which these processes occur. Small changes in the amount, altitude, physical thickness, and/or microphysical properties of clouds due to human influences can exert changes in Earth's radiation budget that are comparable to the radiative forcing by anthropogenic greenhouse gases, thus either partly offsetting or enhancing the warming due to these gases. Because clouds form on aerosol particles, changes in the amount and/or composition of aerosols affect clouds in a variety of ways. The forcing of the radiation balance due to aerosol-cloud interactions (indirect aerosol effect) has large uncertainties because a variety of important processes are not well understood precluding their accurate representation in models.

  17. A Model for the Transport of Sea-Spray Aerosols in the Coastal Zone

    NASA Astrophysics Data System (ADS)

    Piazzola, J.; Tedeschi, G.; Demoisson, A.

    2015-05-01

    We study the dynamics of sea-spray particles in the coastal region of La Reunion Island on the basis of numerical simulations using the transport aerosol model MACMod (Marine Aerosol Concentration Model) and a survey of the aerosol size distributions measured at four locations at two different heights in the north-west part of the island. This allows evaluation of the performance of our model in case of pure marine air masses with implementation of accurate boundary conditions. First of all, an estimate of the aerosol concentration at 10-m height at the upwind boundary of the calculation domain is obtained using a revisited version of the MEDEX (Mediterranean Extinction) model. Estimates of the vertical profile of aerosol concentrations are then provided using aerosol data obtained at two different heights at the upwind boundary of the calculation domain. A parametrization of the vertical profiles of aerosol concentrations for maritime environment is proposed. The results are then compared to the vertical profiles of 0.532 m aerosol particle extinction coefficient obtained from lidar data provided by the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) and also to the data provided by the Aerosol Robotic Network (AERONET). This allows validation of the complete vertical profiles in the mixed layer and shows the validity of satellite data for determination of the vertical profiles. Two kinds of simulation were made: one without a particle advection flux at the upwind boundary of the numerical domain, whereas the second simulation was made with a particle advection flux. In the first case, the influence of the distance to the shoreline on the local sea-spray dynamics is investigated. In the second set of simulation, the particles issued from the local production in the surf zone near the shoreline are mixed with aerosols advected from the remote ocean. A good agreement between the model calculations using our boundary conditions and the data was found. The

  18. Stratospheric aerosol forcing for climate modeling: 1850-1978

    NASA Astrophysics Data System (ADS)

    Arfeuille, Florian; Luo, Beiping; Thomason, Larry; Vernier, Jean-Paul; Peter, Thomas

    2016-04-01

    We present here a stratospheric aerosol dataset produced using the available aerosol optical depth observations from the pre-satellite period. The scarce atmospheric observations are supplemented by additional information from an aerosol microphysical model, initialized by ice-core derived sulfur emissions. The model is used to derive extinctions at all altitudes, latitudes and times when sulfur injections are known for specific volcanic eruptions. The simulated extinction coefficients are then scaled to match the observed optical depths. In order to produce the complete optical properties at all wavelengths (and the aerosol surface area and volume densities) needed by climate models, we assume a lognormal size distribution of the aerosols. Correlations between the extinctions in the visible and the effective radius and distribution width parameters are taken from the better constrained SAGE II period. The aerosol number densities are then fitted to match the derived extinctions in the 1850-1978 period. From these aerosol size distributions, we then calculate extinction coefficients, single scattering albedos and asymmetry factors at all wavelengths using the Mie theory. The aerosol surface area densities and volume densities are also provided.

  19. Aerosol impacts in the Met Office global NWP model

    NASA Astrophysics Data System (ADS)

    Mulcahy, Jane P.; Brooks, Malcolm E.; Milton, Sean F.

    2010-05-01

    An accurate representation of the direct and indirect effect of aerosols is of growing concern for global numerical weather prediction (NWP). Increased scattering and absorption of incoming shortwave (SW) and outgoing longwave radiation (OLR) fields due to the presence of aerosol layers in the atmosphere modifies the atmospheric heating profile and can affect large-scale circulation patterns. The current representation of aerosols in the global NWP configuration of the Met Office Unified ModelTM (MetUM) is based on a simple aerosol climatology (Cusack et al., 1998). Profiles of water soluble dust, soot, oceanic and stratospheric sulphate aerosols are described separately for land and ocean surfaces and are distributed over the boundary layer, free troposphere and stratosphere (sulphates only). While this improved the reflected SW radiative bias at the top-of-atmosphere (TOA), there is evidence that the climatology is too absorbing leading to a temperature bias in the lower troposphere of approximately 0.5 K/day. Furthermore, the omission of the scattering and absorption properties of mineral dust and biomass burning aerosol particles in particular, is believed to be the principal cause of significant model biases (in the region of 50-56 W m-2) in both the model OLR at the TOA (Haywood et al., 2005) and the surface SW radiation fields (Milton et al., 2008). One of the objectives of the Global Aerosols (G-AER) component of the MACC (Monitoring Atmospheric Composition and Climate) project is to evaluate the impact of an improved aerosol representation on the performance of global NWP models. In a stepwise approach of increasing the aerosol complexity in the MetUM, the Cusack climatology is being replaced by the CLASSIC (Coupled Large-scale Aerosol Simulator for Studies in Climate) aerosol scheme, developed for the HadGEM (Hadley Centre Global Environmental Model) climate model. CLASSIC includes representations of external mixtures of sulphate, black carbon, organic

  20. Size distribution dynamics reveal particle-phase chemistry in organic aerosol formation.

    PubMed

    Shiraiwa, Manabu; Yee, Lindsay D; Schilling, Katherine A; Loza, Christine L; Craven, Jill S; Zuend, Andreas; Ziemann, Paul J; Seinfeld, John H

    2013-07-16

    Organic aerosols are ubiquitous in the atmosphere and play a central role in climate, air quality, and public health. The aerosol size distribution is key in determining its optical properties and cloud condensation nucleus activity. The dominant portion of organic aerosol is formed through gas-phase oxidation of volatile organic compounds, so-called secondary organic aerosols (SOAs). Typical experimental measurements of SOA formation include total SOA mass and atomic oxygen-to-carbon ratio. These measurements, alone, are generally insufficient to reveal the extent to which condensed-phase reactions occur in conjunction with the multigeneration gas-phase photooxidation. Combining laboratory chamber experiments and kinetic gas-particle modeling for the dodecane SOA system, here we show that the presence of particle-phase chemistry is reflected in the evolution of the SOA size distribution as well as its mass concentration. Particle-phase reactions are predicted to occur mainly at the particle surface, and the reaction products contribute more than half of the SOA mass. Chamber photooxidation with a midexperiment aldehyde injection confirms that heterogeneous reaction of aldehydes with organic hydroperoxides forming peroxyhemiacetals can lead to a large increase in SOA mass. Although experiments need to be conducted with other SOA precursor hydrocarbons, current results demonstrate coupling between particle-phase chemistry and size distribution dynamics in the formation of SOAs, thereby opening up an avenue for analysis of the SOA formation process.

  1. Aerosol impacts on deep convective storms in the tropics: A combination of modeling and observations

    NASA Astrophysics Data System (ADS)

    Storer, Rachel Lynn

    It is widely accepted that increasing the number of aerosols available to act as cloud condensation nuclei (CCN) will have significant effects on cloud properties, both microphysical and dynamical. This work focuses on the impacts of aerosols on deep convective clouds (DCCs), which experience more complicated responses than warm clouds due to their strong dynamical forcing and the presence of ice processes. Several previous studies have seen that DCCs may be invigorated by increasing aerosols, though this is not the case in all scenarios. The precipitation response to increased aerosol concentrations is also mixed. Often precipitation is thought to decrease due to a less efficient warm rain process in polluted clouds, yet convective invigoration would lead to an overall increase in surface precipitation. In this work, modeling and observations are both used in order to enhance our understanding regarding the effects of aerosols on DCCs. Specifically, the area investigated is the tropical East Atlantic, where dust from the coast of Africa frequently is available to interact with convective storms over the ocean. The first study investigates the effects of aerosols on tropical DCCs through the use of numerical modeling. A series of large-scale, two-dimensional cloud-resolving model simulations was completed, differing only in the concentration of aerosols available to act as CCN. Polluted simulations contained more deep convective clouds, wider storms, higher cloud tops and more convective precipitation across the entire domain. Differences in the warm cloud microphysical processes were largely consistent with aerosol indirect theory, and the average precipitation produced in each DCC column decreased with increasing aerosol concentration. A detailed microphysical budget analysis showed that the reduction in collision and coalescence largely dominated the trend in surface precipitation; however the production of rain through the melting of ice, though it also

  2. Climate implications of carbonaceous aerosols: An aerosol microphysical study using the GISS/MATRIX climate model

    SciTech Connect

    Bauer, Susanne E.; Menon, Surabi; Koch, Dorothy; Bond, Tami; Tsigaridis, Kostas

    2010-04-09

    Recently, attention has been drawn towards black carbon aerosols as a likely short-term climate warming mitigation candidate. However the global and regional impacts of the direct, cloud-indirect and semi-direct forcing effects are highly uncertain, due to the complex nature of aerosol evolution and its climate interactions. Black carbon is directly released as particle into the atmosphere, but then interacts with other gases and particles through condensation and coagulation processes leading to further aerosol growth, aging and internal mixing. A detailed aerosol microphysical scheme, MATRIX, embedded within the global GISS modelE includes the above processes that determine the lifecycle and climate impact of aerosols. This study presents a quantitative assessment of the impact of microphysical processes involving black carbon, such as emission size distributions and optical properties on aerosol cloud activation and radiative forcing. Our best estimate for net direct and indirect aerosol radiative forcing change is -0.56 W/m{sup 2} between 1750 and 2000. However, the direct and indirect aerosol effects are very sensitive to the black and organic carbon size distribution and consequential mixing state. The net radiative forcing change can vary between -0.32 to -0.75 W/m{sup 2} depending on these carbonaceous particle properties. Assuming that sulfates, nitrates and secondary organics form a coating shell around a black carbon core, rather than forming a uniformly mixed particles, changes the overall net radiative forcing from a negative to a positive number. Black carbon mitigation scenarios showed generally a benefit when mainly black carbon sources such as diesel emissions are reduced, reducing organic and black carbon sources such as bio-fuels, does not lead to reduced warming.

  3. Robust calibration of a global aerosol model

    NASA Astrophysics Data System (ADS)

    Lee, L.; Carslaw, K. S.; Pringle, K. J.; Reddington, C.

    2013-12-01

    Comparison of models and observations is vital for evaluating how well computer models can simulate real world processes. However, many current methods are lacking in their assessment of the model uncertainty, which introduces questions regarding the robustness of the observationally constrained model. In most cases, models are evaluated against observations using a single baseline simulation considered to represent the models' best estimate. The model is then improved in some way so that its comparison to observations is improved. Continuous adjustments in such a way may result in a model that compares better to observations but there may be many compensating features which make prediction with the newly calibrated model difficult to justify. There may also be some model outputs whose comparison to observations becomes worse in some regions/seasons as others improve. In such cases calibration cannot be considered robust. We present details of the calibration of a global aerosol model, GLOMAP, in which we consider not just a single model setup but a perturbed physics ensemble with 28 uncertain parameters. We first quantify the uncertainty in various model outputs (CCN, CN) for the year 2008 and use statistical emulation to identify which of the 28 parameters contribute most to this uncertainty. We then compare the emulated model simulations in the entire parametric uncertainty space to observations. Regions where the entire ensemble lies outside the error of the observations indicate structural model error or gaps in current knowledge which allows us to target future research areas. Where there is some agreement with the observations we use the information on the sources of the model uncertainty to identify geographical regions in which the important parameters are similar. Identification of regional calibration clusters helps us to use information from observation rich regions to calibrate regions with sparse observations and allow us to make recommendations for

  4. Stratospheric SO2 and sulfate aerosol: model simulations and satellite observations (Invited)

    NASA Astrophysics Data System (ADS)

    Lelieveld, J.; Bruehl, C.; Hoepfner, M.; Tost, H.

    2013-12-01

    A multiyear study with the atmospheric chemistry - general circulation model EMAC, applying a comprehensive aerosol module, demonstrates that the sulfur gases COS and SO2, the latter from low-latitude volcanic eruptions, predominantly control the stratospheric aerosol. The central role of COS for the non-volcanic background aerosol was recently corroborated by photolytic isotope measurements. Our results suggest that upper stratospheric SO2 can be simulated accurately only when a sulfur sink on meteoritic dust is included and the photolysis of gaseous H2SO4 in the near infrared is higher than assumed previously. We present simulations of the major atmospheric perturbation by Mt. Pinatubo in 1991, and the period from 1999 to 2009 with background aerosol, influenced by 6 medium-strength volcano eruptions. We show comparisons with satellite data for aerosol extinction (e.g. SAGE) and SO2 in the middle atmosphere (MIPAS). They confirm the interannual variability induced by the Quasi-Biennial Oscillation, which is internally generated by the model. The model also realistically simulates the radiative effects of stratospheric and tropospheric aerosol, including influences on the dynamics. The medium strength volcanic eruptions of 2005 and 2006 exerted a non-negligible radiative forcing of up to -0.6 Wm-2 in the tropics, while the large Pinatubo eruption caused a maximum though short-term tropical forcing of about -10 Wm-2. The modeled stratospheric perturbations by volcanic SO2 and their climate impacts can be constrained by measured isotope anomalies produced by UV photolysis.

  5. If I know the aerosol compositional model identifier, how can I get information about the corresponding aerosol model?

    Atmospheric Science Data Center

    2014-12-08

    ... (APOP) and the Mixture files. The Mixture file lists the pure particles in each model identifier. The APOP then gives the detailed information for the pure particles. More information on the MISR aerosol model is available from ...

  6. Models to support active sensing of biological aerosol clouds

    NASA Astrophysics Data System (ADS)

    Brown, Andrea M.; Kalter, Jeffrey M.; Corson, Elizabeth C.; Chaudhry, Zahra; Boggs, Nathan T.; Brown, David M.; Thomas, Michael E.; Carter, Christopher C.

    2013-05-01

    Elastic backscatter LIght Detection And Ranging (LIDAR) is a promising approach for stand-off detection of biological aerosol clouds. Comprehensive models that explain the scattering behavior from the aerosol cloud are needed to understand and predict the scattering signatures of biological aerosols under varying atmospheric conditions and against different aerosol backgrounds. Elastic signatures are dependent on many parameters of the aerosol cloud, with two major components being the size distribution and refractive index of the aerosols. The Johns Hopkins University Applied Physics Laboratory (JHU/APL) has been in a unique position to measure the size distributions of released biological simulant clouds using a wide assortment of aerosol characterization systems that are available on the commercial market. In conjunction with the size distribution measurements, JHU/APL has also been making a dedicated effort to properly measure the refractive indices of the released materials using a thin-film absorption technique and laboratory characterization of the released materials. Intimate knowledge of the size distributions and refractive indices of the biological aerosols provides JHU/APL with powerful tools to build elastic scattering models, with the purpose of understanding, and ultimately, predicting the active signatures of biological clouds.

  7. Role of clouds, aerosols, and aerosol-cloud interaction in 20th century simulations with GISS ModelE2

    NASA Astrophysics Data System (ADS)

    Nazarenko, L.; Rind, D. H.; Bauer, S.; Del Genio, A. D.

    2015-12-01

    Simulations of aerosols, clouds and their interaction contribute to the major source of uncertainty in predicting the changing Earth's energy and in estimating future climate. Anthropogenic contribution of aerosols affects the properties of clouds through aerosol indirect effects. Three different versions of NASA GISS global climate model are presented for simulation of the twentieth century climate change. All versions have fully interactive tracers of aerosols and chemistry in both the troposphere and stratosphere. All chemical species are simulated prognostically consistent with atmospheric physics in the model and the emissions of short-lived precursors [Shindell et al., 2006]. One version does not include the aerosol indirect effect on clouds. The other two versions include a parameterization of the interactive first indirect aerosol effect on clouds following Menon et al. [2010]. One of these two models has the Multiconfiguration Aerosol Tracker of Mixing state (MATRIX) that permits detailed treatment of aerosol mixing state, size, and aerosol-cloud activation. The main purpose of this study is evaluation of aerosol-clouds interactions and feedbacks, as well as cloud and aerosol radiative forcings, for the twentieth century climate under different assumptions and parameterizations for aerosol, clouds and their interactions in the climate models. The change of global surface air temperature based on linear trend ranges from +0.8°C to +1.2°C between 1850 and 2012. Water cloud optical thickness increases with increasing temperature in all versions with the largest increase in models with interactive indirect effect of aerosols on clouds, which leads to the total (shortwave and longwave) cloud radiative cooling trend at the top of the atmosphere. Menon, S., D. Koch, G. Beig, S. Sahu, J. Fasullo, and D. Orlikowski (2010), Black carbon aerosols and the third polar ice cap, Atmos. Chem. Phys., 10,4559-4571, doi:10.5194/acp-10-4559-2010. Shindell, D., G. Faluvegi

  8. Modelling the direct effect of aerosols in the solar near-infrared on a planetary scale

    NASA Astrophysics Data System (ADS)

    Hatzianastassiou, N.; Matsoukas, C.; Fotiadi, A.; Stackhouse, P. W., Jr.; Koepke, P.; Pavlakis, K. G.; Vardavas, I.

    2007-06-01

    We used a spectral radiative transfer model to compute the direct radiative effect (DRE) of natural plus anthropogenic aerosols in the solar near-infrared (IR), between 0.85-10 μm, namely, their effect on the outgoing near-IR radiation at the top of atmosphere (TOA, ΔFTOA), on the atmospheric absorption of near-IR radiation (ΔFatmab) and on the surface downward and absorbed near-IR radiation (ΔFsurf, and ΔFsurfnet, respectively). The computations were performed on a global scale (over land and ocean) under all-sky conditions, using detailed spectral aerosol optical properties taken from the Global Aerosol Data Set (GADS) supplemented by realistic data for the rest of surface and atmospheric parameters. The computed aerosol DRE, averaged over the 12-year period 1984-1995 for January and July, shows that on a global mean basis aerosols produce a planetary cooling by increasing the scattered near-IR radiation back to space by 0.48 W m-2, they warm the atmosphere by 0.37 W m-2 and cool the surface by decreasing the downward and absorbed near-IR radiation at surface by 1.03 and 0.85 W m-2, respectively. The magnitude of the near-IR aerosol DRE is smaller than that of the combined ultraviolet (UV) and visible DRE, but it is still energetically important, since it contributes to the total shortwave (SW) DRE by 22-31%. The aerosol-produced near-IR surface cooling combined with the atmospheric warming, may affect the thermal dynamics of the Earth-atmosphere system, by increasing the atmospheric stability, decreasing thus cloud formation, and precipitation, especially over desertification threatened regions such as the Mediterranean basin. This, together with the fact that the sign of near-IR aerosol DRE is sometimes opposite to that of UV-visible DRE, demonstrates the importance of performing detailed spectral computations to provide estimates of the climatic role of aerosols for the Earth-atmosphere system. This was demonstrated by sensitivity tests revealing very

  9. Measurement and Modeling Results on the Evolution of Aerosol Size Distributions in the Tropics

    NASA Astrophysics Data System (ADS)

    Bahreini, R.; Kazil, J.; Reeves, J. M.; Froyd, K. D.; Wilson, J. C.

    2012-12-01

    Aerosol particles in the upper troposphere-lower stratosphere (UTLS) affect local chemistry and radiation balance due to their role in heterogeneous reactions and contribution to light scattering. Tropical UTLS particles also act as a source of lower stratospheric aerosol populations in the mid-latitudes. Therefore, understanding the processes controlling evolution of the particles in the tropical UTLS is of great importance. We present measurements of aerosol size distributions (4-1000 nm) in the tropics during winter (Pre-AVE, 2004 and CRAVE, 2006) and summer (TC4, 2007), using NMASS (Nuclei Mode Aerosol Size Spectrometer) and FCAS (Focused Cavity Aerosol Spectrometer) instruments aboard the NASA WB-57 aircraft. At altitudes below the tropical tropopause layer (TTL), integrated number and volume distributions indicate a factor of 2-5 variability between 2004 and 2006, reflecting the influence of different air mass origins on the local aerosol population. However, above TTL, the distributions are unified, without a significant change between the two years. Furthermore, above the TTL, number fraction of nucleation mode particles decreases from up to 90% to <40% while total aerosol volume and the volume fraction of particles larger than 350 nm increase. We use an aerosol dynamic model (MAIA, Kazil et al. (2007), Weigel et al. (2011)), constrained by observations to account for the horizontal air mass mixing from mid-latitudes, to simulate aerosol evolution in the tropical UTLS. We will discuss the results of MAIA's sensitivity runs along with the available aerosol composition information to gain insight into the processes controlling the increase in aerosol volume above the TTL. We will also use 2007 observations and MAIA's model results to compare winter-summer aerosol growth processes in the tropical UTLS. Kazil, J., et al., Is aerosol formation in cirrus clouds possible?, Atmos. Chem. Phys., 7, 1407-1413, doi:10.5194/acp-7-1407-2007, 2007. Weigel et al., In situ

  10. An Aerosol Condensation Model for Sulfur Trioxide

    SciTech Connect

    Grant, K E

    2008-02-07

    This document describes a model for condensation of sulfuric acid aerosol given an initial concentration and/or source of gaseous sulfur trioxide (e.g. fuming from oleum). The model includes the thermochemical effects on aerosol condensation and air parcel buoyancy. Condensation is assumed to occur heterogeneously onto a preexisting background aerosol distribution. The model development is both a revisiting of research initially presented at the Fall 2001 American Geophysical Union Meeting [1] and a further extension to provide new capabilities for current atmospheric dispersion modeling efforts [2]. Sulfuric acid is one of the most widely used of all industrial chemicals. In 1992, world consumption of sulfuric acid was 145 million metric tons, with 42.4 Mt (mega-tons) consumed in the United States [10]. In 2001, of 37.5 Mt consumed in the U.S., 74% went into producing phosphate fertilizers [11]. Another significant use is in mining industries. Lawuyi and Fingas [7] estimate that, in 1996, 68% of use was for fertilizers and 5.8% was for mining. They note that H{sub 2}SO{sub 4} use has been and should continue to be very stable. In the United States, the elimination of MTBE (methyl tertiary-butyl ether) and the use of ethanol for gasoline production are further increasing the demand for petroleum alkylate. Alkylate producers have a choice of either a hydrofluoric acid or sulfuric acid process. Both processes are widely used today. Concerns, however, over the safety or potential regulation of hydrofluoric acid are likely to result in most of the growth being for the sulfuric acid process, further increasing demand [11]. The implication of sulfuric acid being a pervasive industrial chemical is that transport is also pervasive. Often, this is in the form of oleum tankers, having around 30% free sulfur trioxide. Although sulfuric acid itself is not a volatile substance, fuming sulfuric acid (referred to as oleum) is [7], the volatile product being sulfur trioxide

  11. Dynamical characteristics of atmospheric aerosols over IG region

    NASA Astrophysics Data System (ADS)

    Sharma, Manish; Singh, Ramesh P.; Kumar, Rajesh

    2016-05-01

    The dynamical characteristics of atmospheric aerosols over the Indo-Gangetic (IG) region are primarily dependent on the geographical settings and meteorological conditions. Detailed analysis of multi satellite data and ground observations have been carried out over three different cities i.e. Kanpur, Greater Noida and Amritsar during 2010-2013. Level-3 Moderate Resolution Imaging Spectroradiometer (MODIS) terra daily global grid product with spatial resolution of 1° × 1° shows the mean AOD at 500 nm wavelength value of 0.73, 0.70 and 0.67 with the standard deviation of 0.43, 0.39 and 0.36 respectively over Amritsar, Greater Noida and Kanpur. Our detailed analysis shows characteristic behavior of aerosols from west to east in the IG region depending upon the proximity of desert regions of Arabia. We have observed large influx of dusts from the Thar desert and Arabia peninsula during pre-monsoon season (April-June), highly affecting Amritsar which is close to the desert region.

  12. Indirect aerosol effect increases CMIP5 models projected Arctic warming

    SciTech Connect

    Chylek, Petr; Vogelsang, Timothy J.; Klett, James D.; Hengartner, Nicholas; Higdon, Dave; Lesins, Glen; Dubey, Manvendra K.

    2016-02-20

    Phase 5 of the Coupled Model Intercomparison Project (CMIP5) climate models’ projections of the 2014–2100 Arctic warming under radiative forcing from representative concentration pathway 4.5 (RCP4.5) vary from 0.9° to 6.7°C. Climate models with or without a full indirect aerosol effect are both equally successful in reproducing the observed (1900–2014) Arctic warming and its trends. However, the 2014–2100 Arctic warming and the warming trends projected by models that include a full indirect aerosol effect (denoted here as AA models) are significantly higher (mean projected Arctic warming is about 1.5°C higher) than those projected by models without a full indirect aerosol effect (denoted here as NAA models). The suggestion is that, within models including full indirect aerosol effects, those projecting stronger future changes are not necessarily distinguishable historically because any stronger past warming may have been partially offset by stronger historical aerosol cooling. In conclusion, the CMIP5 models that include a full indirect aerosol effect follow an inverse radiative forcing to equilibrium climate sensitivity relationship, while models without it do not.

  13. Volcanic Aerosol Evolution: Model vs. In Situ Sampling

    NASA Astrophysics Data System (ADS)

    Pfeffer, M. A.; Rietmeijer, F. J.; Brearley, A. J.; Fischer, T. P.

    2002-12-01

    Volcanoes are the most significant non-anthropogenic source of tropospheric aerosols. Aerosol samples were collected at different distances from 92°C fumarolic source at Poás Volcano. Aerosols were captured on TEM grids coated by a thin C-film using a specially designed collector. In the sampling, grids were exposed to the plume for 30-second intervals then sealed and frozen to prevent reaction before ATEM analysis to determine aerosol size and chemistry. Gas composition was established using gas chromatography, wet chemistry techniques, AAS and Ion Chromatography on samples collected directly from a fumarolic vent. SO2 flux was measured remotely by COSPEC. A Gaussian plume dispersion model was used to model concentrations of the gases at different distances down-wind. Calculated mixing ratios of air and the initial gas species were used as input to the thermo-chemical model GASWORKS (Symonds and Reed, Am. Jour. Sci., 1993). Modeled products were compared with measured aerosol compositions. Aerosols predicted to precipitate out of the plume one meter above the fumarole are [CaSO4, Fe2.3SO4, H2SO4, MgF2. Na2SO4, silica, water]. Where the plume leaves the confines of the crater, 380 meters distant, the predicted aerosols are the same, excepting FeF3 replacing Fe2.3SO4. Collected aerosols show considerable compositional differences between the sampling locations and are more complex than those predicted. Aerosols from the fumarole consist of [Fe +/- Si,S,Cl], [S +/- O] and [Si +/- O]. Aerosols collected on the crater rim consist of the same plus [O,Na,Mg,Ca], [O,Si,Cl +/- Fe], [Fe,O,F] and [S,O +/- Mg,Ca]. The comparison between results obtained by the equilibrium gas model and the actual aerosol compositions shows that an assumption of chemical and thermal equilibrium evolution is invalid. The complex aerosols collected contrast the simple formulae predicted. These findings show that complex, non-equilibrium chemical reactions take place immediately upon volcanic

  14. Modeling Secondary Organic Aerosols over Europe: Impact of Activity Coefficients and Viscosity

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Sartelet, K.; Couvidat, F.

    2014-12-01

    Semi-volatile organic species (SVOC) can condense on suspended particulate materials (PM) in the atmosphere. The modeling of condensation/evaporation of SVOC often assumes that gas-phase and particle-phase concentrations are at equilibrium. However, recent studies show that secondary organic aerosols (SOA) may not be accurately represented by an equilibrium approach between the gas and particle phases, because organic aerosols in the particle phase may be very viscous. The condensation in the viscous liquid phase is limited by the diffusion from the surface of PM to its core. Using a surrogate approach to represent SVOC, depending on the user's choice, the secondary organic aerosol processor (SOAP) may assume equilibrium or model dynamically the condensation/evaporation between the gas and particle phases to take into account the viscosity of organic aerosols. The model is implemented in the three-dimensional chemistry-transport model of POLYPHEMUS. In SOAP, activity coefficients for organic mixtures can be computed using UNIFAC for short-range interactions between molecules and AIOMFAC to also take into account the effect of inorganic species on activity coefficients. Simulations over Europe are performed and POLYPHEMUS/SOAP is compared to POLYPHEMUS/H2O, which was previously used to model SOA using the equilibrium approach with activity coefficients from UNIFAC. Impacts of the dynamic approach on modeling SOA over Europe are evaluated. The concentrations of SOA using the dynamic approach are compared with those using the equilibrium approach. The increase of computational cost is also evaluated.

  15. Dynamics of Aerosol Particles in Stationary, Isotropic Turbulence

    NASA Technical Reports Server (NTRS)

    Collins, Lance R.; Meng, Hui

    2004-01-01

    A detailed study of the dynamics of sub-Kolmogorov-size aerosol particles in stationary isotropic turbulence has been performed. The study combined direct numerical simulations (DNS; directed by Prof. Collins) and high-resolution experimental measurements (directed by Prof. Meng) under conditions of nearly perfect geometric and parametric overlap. The goal was to measure the accumulation of particles in low-vorticity regions of the flow that arises from the effect commonly referred to as preferential concentration. The grant technically was initiated on June 13, 2000; however, funding was not available until July 11, 2000. The grant was originally awarded to Penn State University (numerical simulations) and SUNY-Buffalo (experiments); however, Prof. Collins effort was moved to Cornell University on January 2002 when he joined that university. He completed the study there. A list of the specific tasks that were completed under this study is presented.

  16. Effects of aerosols on tropospheric oxidants: A global model study

    NASA Astrophysics Data System (ADS)

    Tie, Xuexi; Brasseur, Guy; Emmons, Louisa; Horowitz, Larry; Kinnison, Douglas

    2001-10-01

    The global distributions of sulfate and soot particles in the atmosphere are calculated, and the effect of aerosol particles on tropospheric oxidants is studied using a global chemical/transport/aerosol model. The model is developed in the framework of the National Center for Atmospheric Research (NCAR) global three-dimensional chemical/transport model (Model for Ozone and Related Chemical Tracers (MOZART)). In addition to the gas-phase photochemistry implemented in the MOZART model, the present study also accounts for the formation of sulfate and black carbon aerosols as well as for heterogeneous reactions on particles. The simulated global sulfate aerosol distributions and seasonal variation are compared with observations. The seasonal variation of sulfate aerosols is in agreement with measurements, except in the Arctic region. The calculated vertical profiles of sulfate aerosol agree well with the observations over North America. In the case of black carbon the calculated surface distribution is in fair agreement with observations. The effects of aerosol formation and heterogeneous reactions on the surface of sulfate aerosols are studied. The model calculations show the following: (1) The concentration of H2O2 is reduced when sulfate aerosols are formed due to the reaction of SO2 + H2O2 in cloud droplets. The gas-phase reaction SO2 + OH converts OH to HO2, but the reduction of OH and enhancement of HO2 are insignificant (<3%). (2) The heterogeneous reaction of HO2 on the surface of sulfate aerosols produces up to 10% reduction of hydroperoxyl radical (HO2) with an uptake coefficient of 0.2. However, this uptake coefficient could be overestimated, and the results should be regard as an upper limit estimation. (3) The N2O5 reaction on the surface of sulfate aerosols leads to an 80% reduction of NOx at middle to high latitudes during winter. Because ozone production efficiency is low in winter, ozone decreases by only 10% as a result of this reaction. However

  17. Implementing marine organic aerosols into the GEOS-Chem model

    NASA Astrophysics Data System (ADS)

    Gantt, B.; Johnson, M. S.; Crippa, M.; Prévôt, A. S. H.; Meskhidze, N.

    2014-09-01

    Marine organic aerosols (MOA) have been shown to play an important role in tropospheric chemistry by impacting surface mass, cloud condensation nuclei, and ice nuclei concentrations over remote marine and coastal regions. In this work, an online marine primary organic aerosol emission parameterization, designed to be used for both global and regional models, was implemented into the GEOS-Chem model. The implemented emission scheme improved the large underprediction of organic aerosol concentrations in clean marine regions (normalized mean bias decreases from -79% when using the default settings to -12% when marine organic aerosols are added). Model predictions were also in good agreement (correlation coefficient of 0.62 and normalized mean bias of -36%) with hourly surface concentrations of MOA observed during the summertime at an inland site near Paris, France. Our study shows that MOA have weaker coastal-to-inland concentration gradients than sea-salt aerosols, leading to several inland European cities having > 10% of their surface submicron organic aerosol mass concentration with a marine source. The addition of MOA tracers to GEOS-Chem enabled us to identify the regions with large contributions of freshly-emitted or aged aerosol having distinct physicochemical properties, potentially indicating optimal locations for future field studies.

  18. Radiation Transfer Model for Aerosol Events in the Earth Atmosphere

    NASA Astrophysics Data System (ADS)

    Mukai, Sonoyo; Yokomae, Takuma; Nakata, Makiko; Sano, Itaru

    Recently large scale-forest fire, which damages the Earth environment as biomass burning and emission of carbonaceous particles, frequently occurs due to the unstable climate and/or global warming tendency. It is also known that the heavy soil dust is transported from the China continent to Japan on westerly winds, especially in spring. Furthermore the increasing emis-sions of anthropogenic particles associated with continuing economic growth scatter serious air pollutants. Thus atmospheric aerosols, especially in Asia, are very complex and heavy loading, which is called aerosol event. In the case of aerosol events, it is rather difficult to do the sun/sky photometry from the ground, however satellite observation is an effective for aerosol monitoring. Here the detection algorithms from space for such aerosol events as dust storm or biomass burn-ing are dealt with multispectral satellite data as ADEOS-2/GLI, Terra/Aqua/MODIS and/or GOSAT/CAI first. And then aerosol retrieval algorithms are examined based on new radiation transfer code for semi-infinite atmosphere model. The derived space-based results are validated with ground-based measurements and/or model simulations. Namely the space-or surface-based measurements, multiple scattering calculations and model simulations are synthesized together for aerosol retrieval in this work.

  19. Implementing marine organic aerosols into the GEOS-Chem model

    NASA Astrophysics Data System (ADS)

    Gantt, B.; Johnson, M. S.; Crippa, M.; Prévôt, A. S. H.; Meskhidze, N.

    2015-03-01

    Marine-sourced organic aerosols (MOAs) have been shown to play an important role in tropospheric chemistry by impacting surface mass, cloud condensation nuclei, and ice nuclei concentrations over remote marine and coastal regions. In this work, an online marine primary organic aerosol emission parameterization, designed to be used for both global and regional models, was implemented into the GEOS-Chem (Global Earth Observing System Chemistry) model. The implemented emission scheme improved the large underprediction of organic aerosol concentrations in clean marine regions (normalized mean bias decreases from -79% when using the default settings to -12% when marine organic aerosols are added). Model predictions were also in good agreement (correlation coefficient of 0.62 and normalized mean bias of -36%) with hourly surface concentrations of MOAs observed during the summertime at an inland site near Paris, France. Our study shows that MOAs have weaker coastal-to-inland concentration gradients than sea-salt aerosols, leading to several inland European cities having >10% of their surface submicron organic aerosol mass concentration with a marine source. The addition of MOA tracers to GEOS-Chem enabled us to identify the regions with large contributions of freshly emitted or aged aerosol having distinct physicochemical properties, potentially indicating optimal locations for future field studies.

  20. Implementing Marine Organic Aerosols Into the GEOS-Chem Model

    NASA Technical Reports Server (NTRS)

    Johnson, Matthew S.

    2015-01-01

    Marine-sourced organic aerosols (MOA) have been shown to play an important role in tropospheric chemistry by impacting surface mass, cloud condensation nuclei, and ice nuclei concentrations over remote marine and coastal regions. In this work, an online marine primary organic aerosol emission parameterization, designed to be used for both global and regional models, was implemented into the GEOS-Chem model. The implemented emission scheme improved the large under-prediction of organic aerosol concentrations in clean marine regions (normalized mean bias decreases from -79% when using the default settings to -12% when marine organic aerosols are added). Model predictions were also in good agreement (correlation coefficient of 0.62 and normalized mean bias of -36%) with hourly surface concentrations of MOA observed during the summertime at an inland site near Paris, France. Our study shows that MOA have weaker coastal-to-inland concentration gradients than sea-salt aerosols, leading to several inland European cities having > 10% of their surface submicron organic aerosol mass concentration with a marine source. The addition of MOA tracers to GEOS-Chem enabled us to identify the regions with large contributions of freshly-emitted or aged aerosol having distinct physicochemical properties, potentially indicating optimal locations for future field studies.

  1. The Navy Oceanic Vertical Aerosol Model

    DTIC Science & Technology

    1993-12-01

    34windows" exist in the molecular absorption of the electromagnetic energy through which trans- missions in IR communication can take place. In these...the aerosol both scatters and absorbs electromagnetic energy . Of particular interest to the Navy is the role natural marine aerosols play within the...34 \\( )/ •dr12 This technique speeds up the calculations since the integrals can be calculated earlier and their values stored as numbers in a lookup table

  2. A fast aerosol microphysical model for the UTLS

    NASA Astrophysics Data System (ADS)

    Tripathi, S.; Grainger, R.; Rogers, H.

    2003-04-01

    A fast aerosol microphysical model for the UTLS (FAMMUS) has been developed to study aerosol behaviour in UTLS region. This model simulates homogeneous heteromolecular nucleation, condensational growth, coagulation and sedimentation of binary sulphuric acid-water particles together to predict the composition and size-distribution of stratospheric aerosols. This model has already been successfully applied to estimate the changes in background stratospheric aerosol surface area due to aircraft sulphur emission (Tripathi et al., 2002). The principal advantage with this model is that it is non-iterative (Jacobson, 1999), i.e. computing time is minimised by finding semi-implicit solutions to aerosol processes. Condensation and coagulation are solved using operator-split method. Hence the effect of coagulation is determined in a single iteration and the solution is volume conserving for any time-step. The semi-implicit solution for coagulation agrees well with the Smoluchowski's solution for a constant coagulation kernel. Similarly, starting from the fundamental growth equation, solution for condensational growth is derived which does not require iteration. The solution conserves mass exactly, and is unconditionally stable. In the model homogeneous nucleation and condensation is coupled in such a manner that it allows for a realistic competition between the two processes for the limited amount of vapour. With geometrically related size bin (44 bins for sulphuric acid-water particles in the range from 0.3 nm to 5mm) and a 600s time-step the model takes about half an hour to complete a 7 year simulation of stratospheric background aerosols on a work station. FAMMUS has been used to simulate background stratospheric aerosols and volcanically disturbed aerosol and model results are compared favourably with results from earlier model studies and observed data.

  3. Evaluations of tropospheric aerosol properties simulated by the community earth system model with a sectional aerosol microphysics scheme.

    PubMed

    Yu, Pengfei; Toon, Owen B; Bardeen, Charles G; Mills, Michael J; Fan, Tianyi; English, Jason M; Neely, Ryan R

    2015-06-01

    A sectional aerosol model (CARMA) has been developed and coupled with the Community Earth System Model (CESM1). Aerosol microphysics, radiative properties, and interactions with clouds are simulated in the size-resolving model. The model described here uses 20 particle size bins for each aerosol component including freshly nucleated sulfate particles, as well as mixed particles containing sulfate, primary organics, black carbon, dust, and sea salt. The model also includes five types of bulk secondary organic aerosols with four volatility bins. The overall cost of CESM1-CARMA is approximately ∼2.6 times as much computer time as the standard three-mode aerosol model in CESM1 (CESM1-MAM3) and twice as much computer time as the seven-mode aerosol model in CESM1 (CESM1-MAM7) using similar gas phase chemistry codes. Aerosol spatial-temporal distributions are simulated and compared with a large set of observations from satellites, ground-based measurements, and airborne field campaigns. Simulated annual average aerosol optical depths are lower than MODIS/MISR satellite observations and AERONET observations by ∼32%. This difference is within the uncertainty of the satellite observations. CESM1/CARMA reproduces sulfate aerosol mass within 8%, organic aerosol mass within 20%, and black carbon aerosol mass within 50% compared with a multiyear average of the IMPROVE/EPA data over United States, but differences vary considerably at individual locations. Other data sets show similar levels of comparison with model simulations. The model suggests that in addition to sulfate, organic aerosols also significantly contribute to aerosol mass in the tropical UTLS, which is consistent with limited data.

  4. Evaluations of tropospheric aerosol properties simulated by the community earth system model with a sectional aerosol microphysics scheme

    PubMed Central

    Toon, Owen B.; Bardeen, Charles G.; Mills, Michael J.; Fan, Tianyi; English, Jason M.; Neely, Ryan R.

    2015-01-01

    Abstract A sectional aerosol model (CARMA) has been developed and coupled with the Community Earth System Model (CESM1). Aerosol microphysics, radiative properties, and interactions with clouds are simulated in the size‐resolving model. The model described here uses 20 particle size bins for each aerosol component including freshly nucleated sulfate particles, as well as mixed particles containing sulfate, primary organics, black carbon, dust, and sea salt. The model also includes five types of bulk secondary organic aerosols with four volatility bins. The overall cost of CESM1‐CARMA is approximately ∼2.6 times as much computer time as the standard three‐mode aerosol model in CESM1 (CESM1‐MAM3) and twice as much computer time as the seven‐mode aerosol model in CESM1 (CESM1‐MAM7) using similar gas phase chemistry codes. Aerosol spatial‐temporal distributions are simulated and compared with a large set of observations from satellites, ground‐based measurements, and airborne field campaigns. Simulated annual average aerosol optical depths are lower than MODIS/MISR satellite observations and AERONET observations by ∼32%. This difference is within the uncertainty of the satellite observations. CESM1/CARMA reproduces sulfate aerosol mass within 8%, organic aerosol mass within 20%, and black carbon aerosol mass within 50% compared with a multiyear average of the IMPROVE/EPA data over United States, but differences vary considerably at individual locations. Other data sets show similar levels of comparison with model simulations. The model suggests that in addition to sulfate, organic aerosols also significantly contribute to aerosol mass in the tropical UTLS, which is consistent with limited data. PMID:27668039

  5. Aerosol effects on ozone concentrations in Beijing: a model sensitivity study.

    PubMed

    Xu, Jun; Zhang, Yuanhang; Zheng, Shaoqing; He, Youjiang

    2012-01-01

    Most previous O3 simulations were based only on gaseous phase photochemistry. However, some aerosol-related processes, namely, heterogeneous reactions occurring on the aerosol surface and photolysis rate alternated by aerosol radiative influence, may affect O3 photochemistry under high aerosol loads. A three-dimensional air quality model, Models-3/Community Multi-scale Air Quality-Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution, was employed to simulate the effects of the above-mentioned processes on O3 formation under typical high O3 episodes in Beijing during summer. Five heterogeneous reactions, i.e., NO2, NO3, N2O5, HO2, and O3, were individually investigated to elucidate their effects on 03 formation. The results showed that the heterogeneous reactions significantly affected O3 formation in the urban plume. NO2 heterogeneous reaction increased O3 to 90 ppb, while HO2 heterogeneous reaction decreased O3 to 33 ppb. In addition, O3 heterogeneous loss decreased O3 to 31 ppb. The effects of NO2, NO3, and N2O5 heterogeneous reactions showed opposite O3 concentration changes between the urban and extra-urban areas because of the response of the reactions to the two types of O3 formation regimes. When the aerosol radiative influence was included, the photolysis rate decreased and O3 decreased significantly to 73 ppb O3. The two aerosol-related processes should be considered in the study of O3 formation because high aerosol concentration is a ubiquitous phenomenon that affects the urban- and regional air quality in China.

  6. Aerosol interactions with African/Atlantic climate dynamics

    NASA Astrophysics Data System (ADS)

    Hosseinpour, F.; Wilcox, E. M.

    2014-07-01

    Mechanistic relationships exist between variability of dust in the oceanic Saharan air layer (OSAL) and transient changes in the dynamics of Western Africa and the tropical Atlantic Ocean. This study provides evidence of possible interactions between dust in the OSAL region and African easterly jet-African easterly wave (AEJ-AEW) system in the climatology of boreal summer, when easterly wave activity peaks. Synoptic-scale changes in instability and precipitation in the African/Atlantic intertropical convergence zone are correlated with enhanced aerosol optical depth (AOD) in the OSAL region in response to anomalous 3D overturning circulations and upstream/downstream thermal anomalies at above and below the mean-AEJ level. Upstream and downstream anomalies are referred to the daily thermal/dynamical changes over the West African monsoon region and the Eastern Atlantic Ocean, respectively. Our hypothesis is that AOD in the OSAL is positively correlated with the downstream AEWs and negatively correlated with the upstream waves from climatological perspective. The similarity between the 3D pattern of thermal/dynamical anomalies correlated with dust outbreaks and those of AEWs provides a mechanism for dust radiative heating in the atmosphere to reinforce AEW activity. We proposed that the interactions of OSAL dust with regional climate mainly occur through coupling of dust with the AEWs.

  7. In Silico Models of Aerosol Delivery to the Respiratory Tract – Development and Applications

    PubMed Central

    Longest, P. Worth; Holbrook, Landon T.

    2011-01-01

    This review discusses the application of computational models to simulate the transport and deposition of inhaled pharmaceutical aerosols from the site of particle or droplet formation to deposition within the respiratory tract. Traditional one-dimensional (1-D) whole-lung models are discussed briefly followed by a more in-depth review of three-dimensional (3-D) computational fluid dynamics (CFD) simulations. The review of CFD models is organized into sections covering transport and deposition within the inhaler device, the extrathoracic (oral and nasal) region, conducting airways, and alveolar space. For each section, a general review of significant contributions and advancements in the area of simulating pharmaceutical aerosols is provided followed by a more in-depth application or case study that highlights the challenges, utility, and benefits of in silico models. Specific applications presented include the optimization of an existing spray inhaler, development of charge-targeted delivery, specification of conditions for optimal nasal delivery, analysis of a new condensational delivery approach, and an evaluation of targeted delivery using magnetic aerosols. The review concludes with recommendations on the need for more refined model validations, use of a concurrent experimental and CFD approach for developing aerosol delivery systems, and development of a stochastic individual path (SIP) model of aerosol transport and deposition throughout the respiratory tract. PMID:21640772

  8. Implementing marine organic aerosols into the GEOS-Chem model

    DOE PAGES

    Gantt, B.; Johnson, M. S.; Crippa, M.; ...

    2015-03-17

    Marine-sourced organic aerosols (MOAs) have been shown to play an important role in tropospheric chemistry by impacting surface mass, cloud condensation nuclei, and ice nuclei concentrations over remote marine and coastal regions. In this work, an online marine primary organic aerosol emission parameterization, designed to be used for both global and regional models, was implemented into the GEOS-Chem (Global Earth Observing System Chemistry) model. The implemented emission scheme improved the large underprediction of organic aerosol concentrations in clean marine regions (normalized mean bias decreases from -79% when using the default settings to -12% when marine organic aerosols are added). Modelmore » predictions were also in good agreement (correlation coefficient of 0.62 and normalized mean bias of -36%) with hourly surface concentrations of MOAs observed during the summertime at an inland site near Paris, France. Our study shows that MOAs have weaker coastal-to-inland concentration gradients than sea-salt aerosols, leading to several inland European cities having >10% of their surface submicron organic aerosol mass concentration with a marine source. The addition of MOA tracers to GEOS-Chem enabled us to identify the regions with large contributions of freshly emitted or aged aerosol having distinct physicochemical properties, potentially indicating optimal locations for future field studies.« less

  9. Evaluation of the global aerosol microphysical ModelE2-TOMAS model against satellite and ground-based observations

    NASA Astrophysics Data System (ADS)

    Lee, Y. H.; Adams, P. J.; Shindell, D. T.

    2015-03-01

    The TwO-Moment Aerosol Sectional (TOMAS) microphysics model has been integrated into the state-of-the-art general circulation model, GISS ModelE2. This paper provides a detailed description of the ModelE2-TOMAS model and evaluates the model against various observations including aerosol precursor gas concentrations, aerosol mass and number concentrations, and aerosol optical depths. Additionally, global budgets in ModelE2-TOMAS are compared with those of other global aerosol models, and the ModelE2-TOMAS model is compared to the default aerosol model in ModelE2, which is a one-moment aerosol (OMA) model (i.e. no aerosol microphysics). Overall, the ModelE2-TOMAS predictions are within the range of other global aerosol model predictions, and the model has a reasonable agreement (mostly within a factor of 2) with observations of sulfur species and other aerosol components as well as aerosol optical depth. However, ModelE2-TOMAS (as well as ModelE2-OMA) cannot capture the observed vertical distribution of sulfur dioxide over the Pacific Ocean, possibly due to overly strong convective transport and overpredicted precipitation. The ModelE2-TOMAS model simulates observed aerosol number concentrations and cloud condensation nuclei concentrations roughly within a factor of 2. Anthropogenic aerosol burdens in ModelE2-OMA differ from ModelE2-TOMAS by a few percent to a factor of 2 regionally, mainly due to differences in aerosol processes including deposition, cloud processing, and emission parameterizations. We observed larger differences for naturally emitted aerosols such as sea salt and mineral dust, as those emission rates are quite different due to different upper size cutoff assumptions.

  10. Climatic influence of background and volcanic stratosphere aerosol models

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    A simple modelization of the earth atmosphere system including tropospheric and stratospheric aerosols has been derived and tested. Analytical expressions are obtained for the albedo variation due to a thin stratospheric aerosol layer. Also outlined are the physical procedures and the respective influence of the main parameters: aerosol optical thickness, single scattering albedo and asymmetry factor, and sublayer albedo. The method is applied to compute the variation of the zonal and planetary albedos due to a stratospheric layer of background H2SO4 particles and of volcanic ash.

  11. MATRIX (Multiconfiguration Aerosol TRacker of mIXing state): an aerosol microphysical module for global atmospheric models

    NASA Astrophysics Data System (ADS)

    Bauer, S. E.; Wright, D. L.; Koch, D.; Lewis, E. R.; McGraw, R.; Chang, L.-S.; Schwartz, S. E.; Ruedy, R.

    2008-10-01

    A new aerosol microphysical module MATRIX, the Multiconfiguration Aerosol TRacker of mIXing state, and its application in the Goddard Institute for Space Studies (GISS) climate model (ModelE) are described. This module, which is based on the quadrature method of moments (QMOM), represents nucleation, condensation, coagulation, internal and external mixing, and cloud-drop activation and provides aerosol particle mass and number concentration and particle size information for up to 16 mixed-mode aerosol populations. Internal and external mixing among aerosol components sulfate, nitrate, ammonium, carbonaceous aerosols, dust and sea-salt particles are represented. The solubility of each aerosol population, which is explicitly calculated based on its soluble and insoluble components, enables calculation of the dependence of cloud drop activation on the microphysical characterization of multiple soluble aerosol populations. A detailed model description and results of box-model simulations of various aerosol population configurations are presented. The box model experiments demonstrate the dependence of cloud activating aerosol number concentration on the aerosol population configuration; comparisons to sectional models are quite favorable. MATRIX is incorporated into the GISS climate model and simulations are carried out primarily to assess its performance/efficiency for global-scale atmospheric model application. Simulation results were compared with aircraft and station measurements of aerosol mass and number concentration and particle size to assess the ability of the new method to yield data suitable for such comparison. The model accurately captures the observed size distributions in the Aitken and accumulation modes up to particle diameter 1 μm, in which sulfate, nitrate, black and organic carbon are predominantly located; however the model underestimates coarse-mode number concentration and size, especially in the marine environment. This is more likely due to

  12. Stratospheric SO2 and sulphate aerosol, model simulations and satellite observations

    NASA Astrophysics Data System (ADS)

    Brühl, C.; Lelieveld, J.; Höpfner, M.; Tost, H.

    2013-04-01

    A multiyear study with the atmospheric chemistry general circulation model EMAC with the aerosol module GMXe at high altitude resolution demonstrates that the sulfur gases COS and SO2, the latter from low-latitude volcanic eruptions, predominantly control the formation of stratospheric aerosol. The model consistently uses the same parameters in the troposphere and stratosphere for 7 aerosol modes applied. Lower boundary conditions for COS and other long-lived trace gases are taken from measurement networks, while estimates of volcanic SO2 emissions are based on satellite observations. We show comparisons with satellite data for aerosol extinction (e.g. SAGE) and SO2 in the middle atmosphere (MIPAS on ENVISAT). This corroborates the interannual variability induced by the Quasi-Biennial Oscillation, which is internally generated by the model. The model also realistically simulates the radiative effects of stratospheric and tropospheric aerosol including the effects on the model dynamics. The medium strength volcanic eruptions of 2005 and 2006 exerted a nonnegligible radiative forcing of up to -0.6 W m-2 in the tropics, while the large Pinatubo eruption caused a maximum though short term tropical forcing of about -10 W m-2. The study also shows that observed upper stratospheric SO2 can be simulated accurately only when a sulphur sink on meteoritic dust is included and the photolysis of gaseous H2SO4 in the near infrared is higher than assumed previously.

  13. Integrated Analyses of Multiple Worldwide Aerosol Mass Spectrometer Datasets for Improved Understanding of Aerosol Sources and Processes and for Comparison with Global Models

    SciTech Connect

    Zhang, Qi; Jose, Jimenez Luis

    2014-04-28

    The AMS is the only current instrument that provides real-time, quantitative, and size-resolved data on submicron non-refractory aerosol species with a time resolution of a few minutes or better. The AMS field data are multidimensional and massive, containing extremely rich information on aerosol chemistry, microphysics and dynamics—basic information that is required to evaluate and quantify the radiative climate forcing of atmospheric aerosols. The high time resolution of the AMS data also reveals details of aerosol dynamic variations that are vital to understanding the physico-chemical processes of atmospheric aerosols that govern aerosol properties relevant to the climate. There are two primary objectives of this 3-year project. Our first objective is to perform highly integrated analysis of dozens of AMS datasets acquired from various urban, forested, coastal, marine, mountain peak, and rural/remote locations around the world and synthesize and inter-compare results with a focus on the sources and the physico-chemical processes that govern aerosol properties relevant to aerosol climate forcing. Our second objective is to support our collaboration with global aerosol modelers, in which we will supply the size-resolved aerosol composition and temporal variation data (via a public web interface) and our analysis results for use in model testing and validation and for translation of the rich AMS database into model constraints that can improve climate forcing simulations. Several prominent global aerosol modelers have expressed enthusiastic support for this collaboration. The specific tasks that we propose to accomplish include 1) to develop, validate, and apply multivariate analysis techniques for improved characterization and source apportionment of organic aerosols; 2) to evaluate aerosol source regions and relative contributions based on back-trajectory integration (PSCF method); 3) to summarize and synthesize submicron aerosol information, including

  14. PARAGON: A Systematic, Integrated Approach to Aerosol Observation and Modeling

    NASA Technical Reports Server (NTRS)

    Diner, David J.; Kahn, Ralph A.; Braverman, Amy J.; Davies, Roger; Martonchik, John V.; Menzies, Robert T.; Ackerman, Thomas P.; Seinfeld, John H.; Anderson, Theodore L.; Charlson, Robert J.; Bosenberg, Jens; Collins, William D.; Rasch, Philip J.; Holben, Brent N.; Hostetler, Chris A.; Wielicki, Bruce A.; Miller, Mark A.; Schwartz, Stephen E.; Ogren, John A.; Penner, Joyce E.; Stephens, Graeme L.; Torres, Omar; Travis, Larry D.; Yu, Bin

    2004-01-01

    Aerosols are generated and transformed by myriad processes operating across many spatial and temporal scales. Evaluation of climate models and their sensitivity to changes, such as in greenhouse gas abundances, requires quantifying natural and anthropogenic aerosol forcings and accounting for other critical factors, such as cloud feedbacks. High accuracy is required to provide sufficient sensitivity to perturbations, separate anthropogenic from natural influences, and develop confidence in inputs used to support policy decisions. Although many relevant data sources exist, the aerosol research community does not currently have the means to combine these diverse inputs into an integrated data set for maximum scientific benefit. Bridging observational gaps, adapting to evolving measurements, and establishing rigorous protocols for evaluating models are necessary, while simultaneously maintaining consistent, well understood accuracies. The Progressive Aerosol Retrieval and Assimilation Global Observing Network (PARAGON) concept represents a systematic, integrated approach to global aerosol Characterization, bringing together modern measurement and modeling techniques, geospatial statistics methodologies, and high-performance information technologies to provide the machinery necessary for achieving a comprehensive understanding of how aerosol physical, chemical, and radiative processes impact the Earth system. We outline a framework for integrating and interpreting observations and models and establishing an accurate, consistent and cohesive long-term data record.

  15. MATRIX (Multiconfiguration Aerosol TRacker of mIXing state): an aerosol microphysical module for global atmospheric models

    NASA Astrophysics Data System (ADS)

    Bauer, S. E.; Wright, D.; Koch, D.; Lewis, E. R.; McGraw, R.; Chang, L.-S.; Schwartz, S. E.; Ruedy, R.

    2008-05-01

    A new aerosol microphysical module MATRIX, the Multiconfiguation Aerosol TRacker of mIXing state, and its application in the Goddard Institute for Space Studies (GISS) climate model (ModelE) is described. This module, which is based on the quadrature method of moments (QMOM), represents nucleation, condensation, coagulation, internal and external mixing, and cloud-drop activation and provides aerosol particle mass and number concentration and particle size information for up to 16 mixed-mode aerosol populations. Internal and external mixing among aerosol components sulfate, nitrate, ammonium, carbonaceous aerosols, dust and sea-salt particles are represented. The solubility of each aerosol mode, which is explicitly calculated based on its soluble and insoluble components, enables calculation of the dependence of cloud drop activation on the microphysical characterization of multiple soluble modes. A detailed model description and results of box-model simulations of various mode configurations are presented. The number concentration of aerosol particles activated to cloud drops depends on the mode configuration. Simulations on the global scale with the GISS climate model are evaluated against aircraft and station measurements of aerosol mass and number concentration and particle size. The model accurately captures the observed size distributions in the aitken and accumulation modes up to particle diameter 1 μm, in which sulfate, nitrate, black and organic carbon are predominantly located; however the model underestimates coarse-mode number concentration and size, especially in the marine environment.

  16. Indirect aerosol effect increases CMIP5 models projected Arctic warming

    DOE PAGES

    Chylek, Petr; Vogelsang, Timothy J.; Klett, James D.; ...

    2016-02-20

    Phase 5 of the Coupled Model Intercomparison Project (CMIP5) climate models’ projections of the 2014–2100 Arctic warming under radiative forcing from representative concentration pathway 4.5 (RCP4.5) vary from 0.9° to 6.7°C. Climate models with or without a full indirect aerosol effect are both equally successful in reproducing the observed (1900–2014) Arctic warming and its trends. However, the 2014–2100 Arctic warming and the warming trends projected by models that include a full indirect aerosol effect (denoted here as AA models) are significantly higher (mean projected Arctic warming is about 1.5°C higher) than those projected by models without a full indirect aerosolmore » effect (denoted here as NAA models). The suggestion is that, within models including full indirect aerosol effects, those projecting stronger future changes are not necessarily distinguishable historically because any stronger past warming may have been partially offset by stronger historical aerosol cooling. In conclusion, the CMIP5 models that include a full indirect aerosol effect follow an inverse radiative forcing to equilibrium climate sensitivity relationship, while models without it do not.« less

  17. On the Implications of aerosol liquid water and phase separation for modeled organic aerosol mass

    EPA Science Inventory

    Current chemical transport models assume that organic aerosol (OA)-forming compounds partition mostly to a water-poor, organic-rich phase in accordance with their vapor pressures. However, in the southeast United States, a significant fraction of ambient organic compounds are wat...

  18. The MESSy aerosol submodel MADE3 (v2.0b): description and a box model test

    NASA Astrophysics Data System (ADS)

    Kaiser, J. C.; Hendricks, J.; Righi, M.; Riemer, N.; Zaveri, R. A.; Metzger, S.; Aquila, V.

    2014-01-01

    We introduce MADE3 (Modal Aerosol Dynamics model for Europe, adapted for global applications, 3rd generation), an aerosol dynamics submodel for application within the MESSy framework (Modular Earth Submodel System). MADE3 builds on the predecessor aerosol submodels MADE and MADE-in. Its main new features are the explicit representation of coarse particle interactions both with other particles and with condensable gases, and the inclusion of hydrochloric acid (HCl)/chloride (Cl) partitioning between the gas and condensed phases. The aerosol size distribution is represented in the new submodel as a superposition of nine lognormal modes: one for fully soluble particles, one for insoluble particles, and one for mixed particles in each of three size ranges (Aitken, accumulation, and coarse mode size ranges). In order to assess the performance of MADE3 we compare it to its predecessor MADE and to the much more detailed particle-resolved aerosol model PartMC-MOSAIC in a box model simulation of an idealised marine boundary layer test case. MADE3 and MADE results are very similar, except in the coarse mode, where the aerosol is dominated by sea spray particles. Cl is reduced in MADE3 with respect to MADE due to the HCl/Cl partitioning that leads to Cl removal from the sea spray aerosol in our test case. Additionally, aerosol nitrate concentration is higher in MADE3 due to the condensation of nitric acid on coarse particles. MADE3 and PartMC-MOSAIC show substantial differences in the fine particle size distributions (sizes ≲ 2 μm) that could be relevant when simulating climate effects on a global scale. Nevertheless, the agreement between MADE3 and PartMC-MOSAIC is very good when it comes to coarse particle size distribution, and also in terms of aerosol composition. Considering these results and the well-established ability of MADE in reproducing observed aerosol loadings and composition, MADE3 seems suitable for application within a global model.

  19. The Messy Aerosol Submodel MADE3 (v2.0b): Description and a Box Model Test

    NASA Technical Reports Server (NTRS)

    Kaiser, J. C.; Hendricks, J.; Righi, M.; Riemer, N.; Zaveri, R. A.; Metzger, S.; Aquila, Valentina

    2014-01-01

    We introduce MADE3 (Modal Aerosol Dynamics model for Europe, adapted for global applications, 3rd generation), an aerosol dynamics submodel for application within the MESSy framework (Modular Earth Submodel System). MADE3 builds on the predecessor aerosol submodels MADE and MADE-in. Its main new features are the explicit representation of coarse particle interactions both with other particles and with condensable gases, and the inclusion of hydrochloric acid (HCl)chloride (Cl) partitioning between the gas and condensed phases. The aerosol size distribution is represented in the new submodel as a superposition of nine lognormal modes: one for fully soluble particles, one for insoluble particles, and one for mixed particles in each of three size ranges (Aitken, accumulation, and coarse mode size ranges). In order to assess the performance of MADE3 we compare it to its predecessor MADE and to the much more detailed particle-resolved aerosol model PartMC-MOSAIC in a box model simulation of an idealized marine boundary layer test case. MADE3 and MADE results are very similar, except in the coarse mode, where the aerosol is dominated by sea spray particles. Cl is reduced in MADE3 with respect to MADE due to the HClCl partitioning that leads to Cl removal from the sea spray aerosol in our test case. Additionally, aerosol nitrate concentration is higher in MADE3 due to the condensation of nitric acid on coarse particles. MADE3 and PartMC- MOSAIC show substantial differences in the fine particle size distributions (sizes about 2 micrometers) that could be relevant when simulating climate effects on a global scale. Nevertheless, the agreement between MADE3 and PartMC-MOSAIC is very good when it comes to coarse particle size distribution, and also in terms of aerosol composition. Considering these results and the well-established ability of MADE in reproducing observed aerosol loadings and composition, MADE3 seems suitable for application within a global model.

  20. Easy Aerosol - a model intercomparison project to study aerosol-radiative interactions and their impact on regional climate

    NASA Astrophysics Data System (ADS)

    Voigt, A.; Bony, S.; Stevens, B. B.; Boucher, O.; Medeiros, B.; Pincus, R.; Wang, Z.; Zhang, K.; Lewinschal, A.; Bellouin, N.; Yang, Y. M.

    2015-12-01

    Recent studies illustrated the potential of aerosols to change the large-scale atmospheric circulation and precipitation patterns, but it remains unclear to what extent the proposed aerosol-induced changes reflect robust model behavior and are affected by the climate system's internal variability. "Easy Aerosol" addresses this question by subjecting nine comprehensive climate models with prescribed sea-surface temperatures (SSTs) to the same set of idealized "easy" aerosol perturbations. The aerosol perturbations are designed based on a global aerosol climatology and mimic the gravest mode of the anthropogenic aerosol. They both scatter and absorb shortwave radiation, but to focus on direct radiative effects aerosol-cloud interactions are omitted. Each model contributes seven simulations. A clean control case with no aerosol-radiative effects is compared to six perturbed simulations with differing aerosol loading, zonal aerosol distributions, and SSTs. To estimate the role of internal variability, one of the models contributes a 5-member ensemble for each simulation. When observed SSTs from years 1979-2005 are used, the aerosol leads to a local depression of precipitation at the Northern Hemisphere center of the aerosol and a northward shift of the intertropical convergence zone (ITCZ). This is consistent with the aerosol's shortwave atmospheric heating and the fact that SSTs are fixed. Moreover, the Northern hemisphere mid-latitude jet shifts poleward in the annual and zonal-mean. Due to large natura variability, however, these signals only emerge in ensemble runs or if the aerosol optical depth is increased by a factor of five compared to the observed magnitude of the present-day anthropogenic aerosol. When SSTs are adapted to include the cooling effect of the aerosol, the ITCZ and the Northern hemisphere jet shift southward in the annual and zonal-mean. The models exhibit very similar precipitation and zonal wind changes in response to the SST change, showing

  1. Modeling of Aerosol Vertical Profiles Using GIS and Remote Sensing

    PubMed Central

    Wong, Man Sing; Nichol, Janet E.; Lee, Kwon Ho

    2009-01-01

    The use of Geographic Information Systems (GIS) and Remote Sensing (RS) by climatologists, environmentalists and urban planners for three dimensional modeling and visualization of the landscape is well established. However no previous study has implemented these techniques for 3D modeling of atmospheric aerosols because air quality data is traditionally measured at ground points, or from satellite images, with no vertical dimension. This study presents a prototype for modeling and visualizing aerosol vertical profiles over a 3D urban landscape in Hong Kong. The method uses a newly developed technique for the derivation of aerosol vertical profiles from AERONET sunphotometer measurements and surface visibility data, and links these to a 3D urban model. This permits automated modeling and visualization of aerosol concentrations at different atmospheric levels over the urban landscape in near-real time. Since the GIS platform permits presentation of the aerosol vertical distribution in 3D, it can be related to the built environment of the city. Examples are given of the applications of the model, including diagnosis of the relative contribution of vehicle emissions to pollution levels in the city, based on increased near-surface concentrations around weekday rush-hour times. The ability to model changes in air quality and visibility from ground level to the top of tall buildings is also demonstrated, and this has implications for energy use and environmental policies for the tall mega-cities of the future. PMID:22408531

  2. Modeling Aerosol Effects on Clouds and Precipitation: Insights from CalWater 2015

    NASA Astrophysics Data System (ADS)

    Leung, L. R.; Lim, K. S. S.; Fan, J.; Prather, K. A.; DeMott, P. J.; Spackman, J. R.; Ralph, F. M.

    2015-12-01

    The CalWater 2015 field campaign took place in northern California from mid January through early March of 2015. The field campaign, including collaborations between CalWater 2 and ACAPEX, aims to improve understanding and modeling of large-scale dynamics and cloud and precipitation processes associated with atmospheric rivers (ARs) and aerosol-cloud interactions that influence precipitation variability and extremes in the western U.S. An observational strategy was employed using land and offshore assets to monitor (1) the evolution and structure of ARs from near their regions of development, (2) long range transport of aerosols in eastern North Pacific and potential interactions with ARs, and (3) how aerosols from long-range transport and local sources influence cloud and precipitation in the U.S. During the field campaign, an AR developed in the Northeast Pacific Ocean in early February and made landfall in northern California. In-situ aerosol and cloud measurements from the G-1 aircraft; remote sensing data of clouds and aerosols; and meteorological measurements from aircraft, ship, and ground-based instruments collected from February 5 - 8, 2015 are analyzed to characterize the large-scale environment and cloud and precipitation forming processes. Modeling experiments are designed using a regional model for simulations with a cloud resolving limited area domain and quasi-global coarser resolution domain to evaluate the impacts of aerosols on clouds and precipitation, and to explore the relative contributions of long-range transported and regional aerosols that interacted with the clouds before, during, and after AR landfall. Preliminary results will be discussed in the context of the field data as well as a multi-year simulation of the climatological contributions of long-range transported dust during AR landfall in California.

  3. The cloud-aerosol-radiation (CAR) ensemble modeling system

    NASA Astrophysics Data System (ADS)

    Liang, X.-Z.; Zhang, F.

    2013-08-01

    A cloud-aerosol-radiation (CAR) ensemble modeling system has been developed to incorporate the largest choices of alternate parameterizations for cloud properties (cover, water, radius, optics, geometry), aerosol properties (type, profile, optics), radiation transfers (solar, infrared), and their interactions. These schemes form the most comprehensive collection currently available in the literature, including those used by the world's leading general circulation models (GCMs). CAR provides a unique framework to determine (via intercomparison across all schemes), reduce (via optimized ensemble simulations), and attribute specific key factors for (via physical process sensitivity analyses) the model discrepancies and uncertainties in representing greenhouse gas, aerosol, and cloud radiative forcing effects. This study presents a general description of the CAR system and illustrates its capabilities for climate modeling applications, especially in the context of estimating climate sensitivity and uncertainty range caused by cloud-aerosol-radiation interactions. For demonstration purposes, the evaluation is based on several CAR standalone and coupled climate model experiments, each comparing a limited subset of the full system ensemble with up to 896 members. It is shown that the quantification of radiative forcings and climate impacts strongly depends on the choices of the cloud, aerosol, and radiation schemes. The prevailing schemes used in current GCMs are likely insufficient in variety and physically biased in a significant way. There exists large room for improvement by optimally combining radiation transfer with cloud property schemes.

  4. Cloud-Aerosol-Radiation (CAR) ensemble modeling system

    NASA Astrophysics Data System (ADS)

    Liang, X.-Z.; Zhang, F.

    2013-04-01

    A Cloud-Aerosol-Radiation (CAR) ensemble modeling system has been developed to incorporate the largest choices of alternative parameterizations for cloud properties (cover, water, radius, optics, geometry), aerosol properties (type, profile, optics), radiation transfers (solar, infrared), and their interactions. These schemes form the most comprehensive collection currently available in the literature, including those used by the world leading general circulation models (GCMs). The CAR provides a unique framework to determine (via intercomparison across all schemes), reduce (via optimized ensemble simulations), and attribute specific key factors for (via physical process sensitivity analyses) the model discrepancies and uncertainties in representing greenhouse gas, aerosol and cloud radiative forcing effects. This study presents a general description of the CAR system and illustrates its capabilities for climate modeling applications, especially in the context of estimating climate sensitivity and uncertainty range caused by cloud-aerosol-radiation interactions. For demonstration purpose, the evaluation is based on several CAR standalone and coupled climate model experiments, each comparing a limited subset of the full system ensemble with up to 896 members. It is shown that the quantification of radiative forcings and climate impacts strongly depends on the choices of the cloud, aerosol and radiation schemes. The prevailing schemes used in current GCMs are likely insufficient in variety and physically biased in a significant way. There exists large room for improvement by optimally combining radiation transfer with cloud property schemes.

  5. SAGE II aerosol data validation based on retrieved aerosol model size distribution from SAGE II aerosol measurements

    NASA Technical Reports Server (NTRS)

    Wang, Pi-Huan; Mccormick, M. P.; Mcmaster, L. R.; Chu, W. P.; Swissler, T. J.; Osborn, M. T.; Russell, P. B.; Oberbeck, V. R.; Livingston, J.; Rosen, J. M.

    1989-01-01

    Consideration is given to aerosol correlative measurements experiments for the Stratospheric Aerosol and Gas Experiment (SAGE) II, conducted between November 1984 and July 1986. The correlative measurements were taken with an impactor/laser probe, a dustsonde, and an airborne 36-cm lidar system. The primary aerosol quantities measured by the ground-based instruments are compared with those calculated from the aerosol size distributions from SAGE II aerosol extinction measurements. Good agreement is found between the two sets of measurements.

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    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

  8. Impact of Aerosols on Tropical Cyclones: An Investigation Using Convection-permitting Model Simulation

    SciTech Connect

    Hazra, Anupam; Mukhopadhyay, P.; Taraphdar, Sourav; Chen, J. P.; Cotton, William R.

    2013-07-16

    The role of aerosols effect on two tropical cyclones over Bay of Bengal are investigated using a convection permitting model with two-moment mixed-phase bulk cloud microphysics scheme. The simulation results show the role of aerosol on the microphysical and dynamical properties of cloud and bring out the change in efficiency of the clouds in producing precipitation. The tracks of the TCs are hardly affected by the changing aerosol types, but the intensity exhibits significant sensitivity due to the change in aerosol contribution. It is also clearly seen from the analyses that higher heating in the middle troposphere within the cyclone center is in response to latent heat release as a consequence of greater graupel formation. Greater heating in the middle level is particularly noticeable for the clean aerosol regime which causes enhanced divergence in the upper level which, in turn, forces the lower level convergence. As a result, the cleaner aerosol perturbation is more unstable within the cyclone core and produces a more intense cyclone as compared to other two perturbations of aerosol. All these studies show the robustness of the concept of TC weakening by storm ingestion of high concentrations of CCN. The consistency of these model results gives us confidence in stating there is a high probability that ingestion of high CCN concentrations in a TC will lead to weakening of the storm but has little impact on storm direction. Moreover, as pollution is increasing over the Indian sub-continent, this study suggests pollution may be weakening TCs over the Bay of Bengal.

  9. Impact of aerosol direct radiative forcing on the radiative budget, surface heat fluxes, and atmospheric dynamics during the heat wave of summer 2003 over western Europe: A modeling study

    NASA Astrophysics Data System (ADS)

    PéRé, J. C.; Mallet, M.; Pont, V.; Bessagnet, B.

    2011-12-01

    In this work, an off-line coupling between the chemistry-transport model CHIMERE (associated with an aerosol optical module) and the meteorological model Weather Research and Forecasting (WRF) is used to study (1) the direct radiative forcing of pollution aerosols during the heat wave of summer 2003 over western Europe and (2) the possible feedbacks of this direct radiative forcing on the surface-atmosphere system. Simulations performed for the period 7-15 August 2003 reveal a significant decrease of daily mean solar radiation reaching the surface (ΔFBOA = -(10-30) W/m2) because of back scattering at the top of the atmosphere (ΔFTOA = -(1-12) W/m2) and also absorption of solar radiation by polluted particles (ΔFatm = + (5-23) W/m2). During daytime, the aerosol surface dimming induces a mean reduction of both sensible (16 W/m2) and latent (21 W/m2) heat fluxes emitted by the terrestrial surface, resulting in a radiative cooling of the air near the surface (up to 2.9 K/d at noon). Simultaneously, the absorption of solar energy by aerosols causes an atmospheric radiative heating within the planetary boundary layer reaching 1.20 K/d at noon. As a consequence, the direct radiative effect of aerosols is shown to reduce both the planetary boundary layer height (up to 30%) and the horizontal wind speed (up to 6%); that may have contributed to favor the particulate pollution during the heat wave of summer 2003.

  10. Large-Scale Aerosol Modeling and Analysis

    DTIC Science & Technology

    2008-09-30

    aerosol species up to six days in advance anywhere on the globe. NAAPS and COAMPS are particularly useful for forecasts of dust storms in areas...impact cloud processes globally. With increasing dust storms due to climate change and land use changes in desert regions, the impact of the...bacteria in large-scale dust storms is expected to significantly impact warm ice cloud formation, human health, and ecosystems globally. In Niemi et al

  11. Evaluation of aerosol properties simulated by the high resolution global coupled chemistry-aerosol-microphysics model C-IFS-GLOMAP

    NASA Astrophysics Data System (ADS)

    Dhomse, Sandip; Mann, Graham; Carslaw, Ken; Flemming, Johannes; Morcrette, Jean-Jacques; Engelen, Richard; Remy, Samuel; Boucher, Olivier; Benduhn, Francois; Hewson, Will; Woodhouse, Matthew

    2016-04-01

    The EU Framework Programme GEMS and MACC consortium projects co-ordinated by the European Centre for Medium-range Weather Forecasts (ECMWF) have developed an operational global forecasting and reanalysis system (Composition-IFS) for atmospheric composition including greenhouse gases, reactive gases and aerosol. The current operational C-IFS system uses a mass-based aerosol model coupled to data assimilation of Aerosol Optical Depth measured by satellite (MODIS) to predict global aerosol properties. During MACC, the GLOMAP-mode aerosol microphysics scheme was added to the system, providing information on aerosol size and number for improved representation of aerosol-radiation and aerosol-cloud interactions, accounting also for simulated global variations in size distribution and internally-mixed particle composition. The IFS-GLOMAP system has recently been upgraded to couple with the sulphur cycle simulated in the online TM5 tropospheric chemistry module for global reactive gases. This C-IFS-GLOMAP system is also being upgraded to use a new "nitrate-extended" version of GLOMAP which realistically treats the size-resolved gas-particle partitioning of semi volatile gases ammonia and nitric acid. In this poster we described C-IFS-GLOMAP and present an evaluation of the global sulphate aerosol distribution simulated in this coupled aerosol-chemistry C-IFS-GLOMAP, comparing to surface observations in Europe, North America and the North Atlantic and contrasting to the fixed timescale sulphate production scheme developed in GEMS. We show that the coupling to the TM5 sulphur chemistry improves the seasonal cycle of sulphate aerosol, for example addressing a persistent wintertime sulphate high bias in northern Europe. The improved skill in simulated sulphate aerosol seasonal cycle is a pre-requisite to realistically characterise nitrate aerosol since biases in sulphate affect the amount of free ammonia available to form ammonium nitrate.

  12. MATCH-SALSA - Multi-scale Atmospheric Transport and CHemistry model coupled to the SALSA aerosol microphysics model - Part 1: Model description and evaluation

    NASA Astrophysics Data System (ADS)

    Andersson, C.; Bergström, R.; Bennet, C.; Robertson, L.; Thomas, M.; Korhonen, H.; Lehtinen, K. E. J.; Kokkola, H.

    2015-02-01

    We have implemented the sectional aerosol dynamics model SALSA (Sectional Aerosol module for Large Scale Applications) in the European-scale chemistry-transport model MATCH (Multi-scale Atmospheric Transport and Chemistry). The new model is called MATCH-SALSA. It includes aerosol microphysics, with several formulations for nucleation, wet scavenging and condensation. The model reproduces observed higher particle number concentration (PNC) in central Europe and lower concentrations in remote regions. The modeled PNC size distribution peak occurs at the same or smaller particle size as the observed peak at four measurement sites spread across Europe. Total PNC is underestimated at northern and central European sites and accumulation-mode PNC is underestimated at all investigated sites. The low nucleation rate coefficient used in this study is an important reason for the underestimation. On the other hand, the model performs well for particle mass (including secondary inorganic aerosol components), while elemental and organic carbon concentrations are underestimated at many of the sites. Further development is needed, primarily for treatment of secondary organic aerosol, in terms of biogenic emissions and chemical transformation. Updating the biogenic secondary organic aerosol (SOA) scheme will likely have a large impact on modeled PM2.5 and also affect the model performance for PNC through impacts on nucleation and condensation.

  13. Modeling aerosol-water interactions in subsaturated and supersaturated environments

    NASA Astrophysics Data System (ADS)

    Fountoukis, Christos

    The current dissertation is motivated by the need for an improved understanding of aerosol - water interactions both in subsaturated and supersaturated atmospheric conditions with a strong emphasis on air pollution and climate change modeling. A cloud droplet formation parameterization was developed to (i) predict droplet formation from a lognormal representation of aerosol size distribution and composition, and, (ii) include a size-dependant mass transfer coefficient for the growth of water droplets which explicitly accounts for the impact of organics on droplet growth kinetics. The parameterization unravels most of the physics of droplet formation and is in remarkable agreement with detailed numerical parcel model simulations, even for low values of the accommodation coefficient. The parameterization offers a much needed rigorous and computationally inexpensive framework for directly linking complex chemical effects on aerosol activation in global climate models. The new aerosol activation parameterization was also tested against observations from highly polluted clouds (within the vicinity of power plant plumes). Remarkable closure was achieved (much less than the 20% measurement uncertainty). The error in predicted cloud droplet concentration was mostly sensitive to updraft velocity. Optimal closure is obtained if the water vapor uptake coefficient is equal to 0.06. These findings can serve as much needed constraints in modeling of aerosol-cloud interactions in the North America. Aerosol-water interactions in ambient relative humidities less than 100% were studied using a thermodynamic equilibrium model for inorganic aerosol and a three dimensional air quality model. We developed a new thermodynamic equilibrium model, ISORROPIA-II, which predicts the partitioning of semi-volatiles and the phase state of K+/Ca2+/M g2+ /NH4+/Na+/SO4 2-/NO3-/Cl-/H2O aerosols. A comprehensive evaluation of its performance was conducted over a wide range of atmospherically relevant

  14. Size distribution dynamics reveal particle-phase chemistry in organic aerosol formation

    NASA Astrophysics Data System (ADS)

    Shiraiwa, M.; Yee, L. D.; Schilling, K.; Loza, C. L.; Craven, J. S.; Zuend, A.; Ziemann, P. J.; Seinfeld, J.

    2013-12-01

    Organic aerosols are ubiquitous in the atmosphere and play a central role in climate, air quality and public health. The aerosol size distribution is key in determining its optical properties and cloud condensation nucleus activity. The dominant portion of organic aerosol is formed through gas-phase oxidation of volatile organic compounds, so-called secondary organic aerosol (SOA). Typical experimental measurements of SOA formation include total SOA mass and atomic oxygen-to-carbon ratio. These measurements, alone, are generally insufficient to reveal the extent to which condensed-phase reactions occur in conjunction with the multi-generation gas-phase photooxidation. Combining laboratory chamber experiments and kinetic gas-particle modeling for the dodecane SOA system, here we show that the presence of particle-phase chemistry is reflected in the evolution of the SOA size distribution as well as its mass concentration. Particle-phase reactions are predicted to occur mainly at the particle surface and the reaction products contribute more than half of the SOA mass. Chamber photooxidation with a mid-experiment aldehyde injection confirms that heterogeneous reaction of aldehydes with organic hydroperoxides forming peroxyhemiacetals can lead to a large increase in SOA mass. The results of the current work have a number of implications for SOA models. While the dynamics of an aerosol size distribution reflects the mechanism of growth, we demonstrate here that it provides a key constraint in interpreting laboratory and ambient SOA formation. This work, although carried out specifically for the long chain alkane, dodecane, is expected to be widely applicable to other major classes of SOA precursors. SOA consists of a myriad of organic compounds containing various functional groups, which can generally undergo heterogeneous/multiphase reactions forming low-volatility products such as oligomers and other high molecular mass compounds. If particle-phase chemistry is indeed

  15. Effects of Aerosol on Atmospheric Dynamics and Hydrologic Processes During Boreal Spring and Summer

    NASA Technical Reports Server (NTRS)

    Lau, William K. M.; Kim, M. K.; Kim, K. M.; Chin, Mian

    2005-01-01

    Global and regional climate impacts of present-day aerosol loading during boreal spring are investigated using the NASA finite volume General Circulation Model (fvGCM). Three-dimensional distributions of loadings of five species of tropospheric aerosols, i.e., sulfate, black carbon, organic carbon, soil dust, and sea salt are prescribed from outputs of the Goddard Ozone Chemistry Aerosol Radiation and Transport model (GOCART). The aerosol loadings are used to calculate the extinction coefficient, single scattering albedo, and asymmetric factor at eleven spectral wavelengths in the radiative transfer code. We find that aerosol-radiative forcing during boreal spring excites a wavetrain-like pattern in tropospheric temperature and geopotential height that emanates from Northern Africa, through Eurasia, to northeastern Pacific. Associated with the teleconnection is strong surface cooling over regions with large aerosol loading, i.e., China, India, and Africa. Low-to-mid tropospheric heating due to shortwave absorption is found in regions with large loading of dust (Northern Africa, and central East Asia), and black carbon (South and East Asia). In addition pronounced surface cooling is found over the Caspian Sea and warming over Eurasian and northeastern Asia, where aerosol loadings are relatively low. These warming and cooling are components of teleconnection pattern produced primarily by atmospheric heating from absorbing aerosols, i.e., dust from North Africa and black carbon from South and East Asia. Effects of aerosols on atmospheric hydrologic cycle in the Asian monsoon region are also investigated. Results show that absorbing aerosols, i.e., black carbon and dust, induce large-scale upper-level heating anomaly over the Tibetan Plateau in April and May, ushering in an early onset of the Indian summer monsoon. Absorbing aerosols also enhance lower-level heating and anomalous ascent over northern India, intensifying the Indian monsoon. Overall, the aerosol

  16. Effects of Aerosol on Atmospheric Dynamics and Hydrologic Processes during Boreal Spring and Summer

    NASA Technical Reports Server (NTRS)

    Lau, William K. M.; Kim, M. K.; Chin, Mian; Kim, K. M.

    2005-01-01

    Global and regional climate impacts of present-day aerosol loading during boreal spring are investigated using the NASA finite volume General Circulation Model (fvGCM). Three-dimensional distributions of loadings of five species of tropospheric aerosols, i.e., sulfate, black carbon, organic carbon, soil dust, and sea salt are prescribed from outputs of the Goddard Ozone Chemistry Aerosol Radiation and Transport model (GOCART). The aerosol loadings are used to calculate the extinction coefficient, single scattering albedo, and asymmetric factor at eleven spectral wavelengths in the radiative transfer code. We find that aerosol-radiative forcing during boreal spring excites a wavetrain-like pattern in tropospheric temperature and geopotential height that emanates from Northern Africa, through Eurasia, to northeastern Pacific. Associated with the teleconnection is strong surface cooling over regions with large aerosol loading, i.e., China, India, and Africa. Low-to-mid tropospheric heating due to shortwave absorption is found in regions with large loading of dust (Northern Africa, and central East Asia), and black carbon (South and East Asia). In addition pronounced surface cooling is found over the Caspian Sea and warming over Eurasian and northeastern Asia, where aerosol loadings are relatively low. These warming and cooling are components of teleconnection pattern produced primarily by atmospheric heating from absorbing aerosols, i.e., dust from North Africa and.black carbon from South and East Asia. Effects of aerosols on atmospheric hydrologic cycle in the Asian monsoon region are also investigated. Results show that absorbing aerosols, i.e., black carbon and dust, induce large-scale upper-level heating anomaly over the Tibetan Plateau in April and May, ushering in an early onset of the Indian summer monsoon. Absorbing aerosols also enhance lower-level heating and anomalous ascent over northern India, intensifying the Indian monsoon. Overall, the aerosol

  17. Aerosol dynamics above the water area of the Peter the Great Bay during the dust storm in the Gobi desert

    NASA Astrophysics Data System (ADS)

    Bukin, O. A.; Pavlov, A. N.; Kulchin, J. N.; Shmirko, K. A.; Salyuk, P. A.; Stoluarchuk, S. Y.

    2006-11-01

    This article presents aerosol dynamic monitoring over the Peter the Great bay during dust storms in continental areas of the China and Mongolia. Both satellite and lidar data was analyzed. Vertical profiles of aerosol backscattering coefficient and aerosol optical thickness were calculated. Aerosol optical thickness in different layers were retrieved and compared with the satellite ones. Correlation coefficient between satellite and lidar data was calculated. Aerosol layer location was compared to Brent-Vaisal criterion of stability. Aerosol layer stratification during spring - summer (April - June 2006) period was analyzed.

  18. Dust in the Sky: Atmospheric Composition. Modeling of Aerosol Optical Thickness

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Ginoux, Paul; Kinne, Stefan; Torres, Omar; Holben, Brent; Duncan, Bryan; Martin, Randall; Logan, Jennifer; Higurashi, Akiko; Nakajima, Teruyuki

    2000-01-01

    Aerosol is any small particle of matter that rests suspended in the atmosphere. Natural sources, such as deserts, create some aerosols; consumption of fossil fuels and industrial activity create other aerosols. All the microscopic aerosol particles add up to a large amount of material floating in the atmosphere. You can see the particles in the haze that floats over polluted cities. Beyond this visible effect, aerosols can actually lower temperatures. They do this by blocking, or scattering, a portion of the sun's energy from reaching the surface. Because of this influence, scientists study the physical properties of atmospheric aerosols. Reliable numerical models for atmospheric aerosols play an important role in research.

  19. Exploration of the link between Emiliania huxleyi bloom dynamics and aerosol fluxes to the lower Atmosphere

    NASA Astrophysics Data System (ADS)

    Trainic, M.

    2013-12-01

    Phytoplankton blooms are responsible for about 50% of the global photosynthesis, thus are a key component of the major nutrient cycles in the ocean. These blooms can be a significant source for flux of volatiles and aerosols, affecting physical chemical processes in the atmosphere. One of the most widely distributed and abundant phytoplankton species in the oceans is the coccolithophore Emiliania huxleyi. In this research, we explore the influence of the different stages of E. huxleyi bloom on the emission of primary aerosols. For this purpose, we conducted a series of controlled lab experiments to measure aerosol emissions during the growth of E. huxleyi. The cultures were grown in a specially designed growth chamber, and the aerosols were generated in a bubbling system. We collected the emitted aerosol particles on filters, and conducted a series of analysis. Scanning electron microscopy (SEM) analysis of the aerosols emitted from E.huxleyi 1216 cultures demonstrate emission of CaCO3 platelets from their exoskeleton into the air, while coccolithophores cells were absent. The results suggest that while healthy coccolithophore cells are too heavy to aerosolize, during cell lysis the coccoliths shed from the coccolithophore cells are emitted into the atmosphere. Therefore, aerosol production during bloom demise may be greater than from healthy E.huxleyi populations. We also investigated the size distribution of the aerosols at various stages of E. huxleyi growth. The presence of calcified cells greatly effects the size distribution of the emitted aerosol population. This work motivated us to explore aerosols emitted during E. huxleyi spring bloom, in a laboratory we constructed onboard the R/V Knorr research vessel, as part of the North Atlantic Virus Infection of Coccolithophore Expedition (June-July 2012). These results have far-reaching implications on the effect of E. huxleyi bloom dynamics on aerosol properties. We not only show that the E. huxleyi calcite

  20. Detecting Aerosol Effect on Deep Precipitation Systems: A Modeling Study

    NASA Astrophysics Data System (ADS)

    Li, X.; Tao, W.; Khain, A.; Kummerow, C.; Simpson, J.

    2006-05-01

    Urban cities produce high concentrations of anthropogenic aerosols. These aerosols are generally hygroscopic and may serve as Cloud Condensation Nuclei (CCN). This study focuses on the aerosol indirect effect on the deep convective systems over the land. These deep convective systems contribute to the majority of the summer time rainfall and are important for local hydrological cycle and weather forecast. In a companion presentation (Tao et al.) in this session, the mechanisms of aerosol-cloud-precipitation interactions in deep convective systems are explored using cloud-resolving model simulations. Here these model results will be analyzed to provide guidance to the detection of the impact of aerosols as CCN on summer time, deep convections using the currently available observation methods. The two-dimensional Goddard Cumulus Ensemble (GCE) model with an explicit microphysical scheme has been used to simulate the aerosol effect on deep precipitation systems. This model simulates the size distributions of aerosol particles, as well as cloud, rain, ice crystals, snow, graupel, and hail explicitly. Two case studies are analyzed: a midlatitude summer time squall in Oklahoma, and a sea breeze convection in Florida. It is shown that increasing the CCN number concentration does not affect the rainfall structure and rain duration in these two cases. The total surface rainfall rate is reduced in the squall case, but remains essentially the same in the sea breeze case. For the long-lived squall system with a significant portion of the stratiform rain, the surface rainfall PDF (probability density function) distribution is more sensitive to the change of the initial CCN concentrations compared with the total surface rainfall. The possibility of detecting the aerosol indirect effect in deep precipitation systems from the space is also studied in this presentation. The hydrometeors fields from the GCE model simulations are used as inputs to a microwave radiative transfer model

  1. Incorporation of advanced aerosol activation treatments into CESM/CAM5: model evaluation and impacts on aerosol indirect effects

    NASA Astrophysics Data System (ADS)

    Gantt, B.; He, J.; Zhang, X.; Zhang, Y.; Nenes, A.

    2014-07-01

    One of the greatest sources of uncertainty in the science of anthropogenic climate change is from aerosol-cloud interactions. The activation of aerosols into cloud droplets is a direct microphysical linkage between aerosols and clouds; parameterizations of this process link aerosol with cloud condensation nuclei (CCN) and the resulting indirect effects. Small differences between parameterizations can have a large impact on the spatiotemporal distributions of activated aerosols and the resulting cloud properties. In this work, we incorporate a series of aerosol activation schemes into the Community Atmosphere Model version 5.1.1 within the Community Earth System Model version 1.0.5 (CESM/CAM5) which include factors such as insoluble aerosol adsorption and giant cloud condensation nuclei (CCN) activation kinetics to understand their individual impacts on global-scale cloud droplet number concentration (CDNC). Compared to the existing activation scheme in CESM/CAM5, this series of activation schemes increase the computation time by ~10% but leads to predicted CDNC in better agreement with satellite-derived/in situ values in many regions with high CDNC but in worse agreement for some regions with low CDNC. Large percentage changes in predicted CDNC occur over desert and oceanic regions, owing to the enhanced activation of dust from insoluble aerosol adsorption and reduced activation of sea spray aerosol after accounting for giant CCN activation kinetics. Comparison of CESM/CAM5 predictions against satellite-derived cloud optical thickness and liquid water path shows that the updated activation schemes generally improve the low biases. Globally, the incorporation of all updated schemes leads to an average increase in column CDNC of 150% and an increase (more negative) in shortwave cloud forcing of 12%. With the improvement of model-predicted CDNCs and better agreement with most satellite-derived cloud properties in many regions, the inclusion of these aerosol activation

  2. Easy Aerosol - Robust and non-robust circulation responses to aerosol radiative forcing in comprehensive atmosphere models

    NASA Astrophysics Data System (ADS)

    Voigt, Aiko; Bony, Sandrine; Stevens, Bjorn; Boucher, Olivier; Medeiros, Brian; Pincus, Robert; Wang, Zhili; Zhang, Kai; Lewinschal, Anna; Bellouin, Nicolas; Yang, Young-Min

    2015-04-01

    A number of recent studies illustrated the potential of aerosols to change the large-scale atmospheric circulation and precipitation patterns. It remains unclear, however, to what extent the proposed aerosol-induced changes reflect robust model behavior or are affected by uncertainties in the models' treatment of parametrized physical processes, such as those related to clouds. "Easy Aerosol", a model-intercomparison project organized within the Grand Challenge on Clouds, Circulation and Climate Sensitivity of the World Climate Research Programme, addresses this question by subjecting a suite of comprehensive atmosphere general circulation models with prescribed sea-surface temperatures (SSTs) to the same set of idealized "easy" aerosol perturbations. This contribution discusses the aerosol perturbations as well as their impact on the model's precipitation and surface winds. The aerosol perturbations are designed based on a global aerosol climatology and mimic the gravest mode of the anthropogenic aerosol. Specifically, the meridional and zonal distributions of total aerosol optical depth are approximated by a superposition of Gaussian plumes; the vertical distribution is taken as constant within the lowest 1250m of the atmosphere followed by an exponential decay with height above. The aerosol both scatters and absorbs shortwave radiation, but in order to focus on direct radiative effects aerosol-cloud interactions are omitted. Each model contributes seven simulations. A clean control case with no aerosol-radiative effects at all is compared to six perturbed simulations with differing aerosol loading, zonal aerosol distributions, and SSTs. To estimate the role of natural variability, one of the models, MPI-ESM, contributes a 5-member ensemble for each simulation. If the observed SSTs from years 1979-2005 are prescribed, the aerosol leads to a local depression of precipitation at the Northern Hemisphere center of the aerosol and a northward shift of the

  3. Improving aerosol interaction with clouds and precipitation in a regional chemical weather modeling system

    NASA Astrophysics Data System (ADS)

    Zhou, C.; Zhang, X.; Gong, S.; Wang, Y.; Xue, M.

    2015-06-01

    A comprehensive aerosol-cloud-precipitation interaction (ACI) scheme has been developed under CMA chemical weather modeling system GRAPES/CUACE. Calculated by a sectional aerosol activation scheme based on the information of size and mass from CUACE and the thermal-dynamic and humid states from the weather model GRAPES at each time step, the cloud condensation nuclei (CCN) is fed online interactively into a two-moment cloud scheme (WDM6) and a convective parameterization to drive the cloud physics and precipitation formation processes. The modeling system has been applied to study the ACI for January 2013 when several persistent haze-fog events and eight precipitation events occurred. The results show that interactive aerosols with the WDM6 in GRAPES/CUACE obviously increase the total cloud water, liquid water content and cloud droplet number concentrations while decrease the mean diameter of cloud droplets with varying magnitudes of the changes in each case and region. These interactive micro-physical properties of clouds improve the calculation of their collection growth rates in some regions and hence the precipitation rate and distributions in the model, showing 24 to 48% enhancements of TS scoring for 6 h precipitation in almost all regions. The interactive aerosols with the WDM6 also reduce the regional mean bias of temperature by 3 °C during certain precipitation events, but the monthly means bias is only reduced by about 0.3 °C.

  4. Improving aerosol interaction with clouds and precipitation in a regional chemical weather modeling system

    NASA Astrophysics Data System (ADS)

    Zhou, C.; Zhang, X.; Gong, S.

    2015-12-01

    A comprehensive aerosol-cloud-precipitation interaction (ACI) scheme has been developed under CMA chemical weather modeling system GRAPES/CUACE. Calculated by a sectional aerosol activation scheme based on the information of size and mass from CUACE and the thermal-dynamic and humid states from the weather model GRAPES at each time step, the cloud condensation nuclei (CCN) is fed online interactively into a two-moment cloud scheme (WDM6) and a convective parameterization to drive the cloud physics and precipitation formation processes. The modeling system has been applied to study the ACI for January 2013 when several persistent haze-fog events and eight precipitation events occurred. The results show that interactive aerosols with the WDM6 in GRAPES/CUACE obviously increase the total cloud water, liquid water content and cloud droplet number concentrations while decrease the mean diameter of cloud droplets with varying magnitudes of the changes in each case and region. These interactive micro-physical properties of clouds improve the calculation of their collection growth rates in some regions and hence the precipitation rate and distributions in the model, showing 24% to 48% enhancements of TS scoring for 6-h precipitation in almost all regions. The interactive aerosols with the WDM6 also reduce the regional mean bias of temperature by 3 °C during certain precipitation events, but the monthly means bias is only reduced by about 0.3°C.

  5. Model evaluation of marine primary organic aerosol emission schemes

    NASA Astrophysics Data System (ADS)

    Gantt, B.; Johnson, M. S.; Meskhidze, N.; Sciare, J.; Ovadnevaite, J.; Ceburnis, D.; O'Dowd, C. D.

    2012-09-01

    In this study, several marine primary organic aerosol (POA) emission schemes have been evaluated using the GEOS-Chem chemical transport model in order to provide guidance for their implementation in air quality and climate models. These emission schemes, based on varying dependencies of chlorophyll a concentration ([chl a]) and 10 m wind speed (U10), have large differences in their magnitude, spatial distribution, and seasonality. Model comparison with weekly and monthly mean values of the organic aerosol mass concentration at two coastal sites shows that the source function exclusively related to [chl a] does a better job replicating surface observations. Sensitivity simulations in which the negative U10 and positive [chl a] dependence of the organic mass fraction of sea spray aerosol are enhanced show improved prediction of the seasonality of the marine POA concentrations. A top-down estimate of submicron marine POA emissions based on the parameterization that compares best to the observed weekly and monthly mean values of marine organic aerosol surface concentrations has a global average emission rate of 6.3 Tg yr-1. Evaluation of existing marine POA source functions against a case study during which marine POA contributed the major fraction of submicron aerosol mass shows that none of the existing parameterizations are able to reproduce the hourly-averaged observations. Our calculations suggest that in order to capture episodic events and short-term variability in submicron marine POA concentration over the ocean, new source functions need to be developed that are grounded in the physical processes unique to the organic fraction of sea spray aerosol.

  6. A model for predicting fog aerosol size distributions

    NASA Astrophysics Data System (ADS)

    Rudiger, Joshua J.; Book, Kevin; Baker, Brooke; deGrassie, John Stephen; Hammel, Stephen

    2016-09-01

    An accurate model and parameterization of fog is needed to increase the reliability and usefulness of electro-optical systems in all relevant environments. Current models vary widely in their ability to accurately predict the size distribution and subsequent optical properties of fog. The Advanced Navy Aerosol Model (ANAM), developed to model the distribution of aerosols in the maritime environment, does not currently include a model for fog. One of the more prevalent methods for modeling particle size spectra consists of fitting a modified gamma function to fog measurement data. This limits the fog distribution to a single mode. Here we establish an empirical model for predicting complicated multimodal fog droplet size spectra using machine learning techniques. This is accomplished through careful measurements of fog in a controlled laboratory environment and measuring fog particle size distributions during outdoor fog events.

  7. Estimated SAGE II ozone mixing ratios in early 1993 and comparisons with Stratospheric Photochemistry, Aerosols and Dynamic Expedition measurements

    NASA Technical Reports Server (NTRS)

    Yue, G. K.; Veiga, R. E.; Poole, L. R.; Zawodny, J. M.; Proffitt, M. H.

    1994-01-01

    An empirical time-series model for estimating ozone mixing ratios based on Stratospheric Aerosols and Gas Experiment II (SAGE II) monthly mean ozone data for the period October 1984 through June 1991 has been developed. The modeling results for ozone mixing ratios in the 10- to 30- km region in early months of 1993 are presented. In situ ozone profiles obtained by a dual-beam UV-absorption ozone photometer during the Stratospheric Photochemistry, Aerosols and Dynamics Expedition (SPADE) campaign, May 1-14, 1993, are compared with the model results. With the exception of two profiles at altitudes below 16 km, ozone mixing ratios derived by the model and measured by the ozone photometer are in relatively good agreement within their individual uncertainties. The identified discrepancies in the two profiles are discussed.

  8. Advancing Models and Evaluation of Cumulus, Climate and Aerosol Interactions

    SciTech Connect

    Gettelman, Andrew

    2015-10-27

    This project was successfully able to meet its’ goals, but faced some serious challenges due to personnel issues. Nonetheless, it was largely successful. The Project Objectives were as follows: 1. Develop a unified representation of stratifom and cumulus cloud microphysics for NCAR/DOE global community models. 2. Examine the effects of aerosols on clouds and their impact on precipitation in stratiform and cumulus clouds. We will also explore the effects of clouds and precipitation on aerosols. 3. Test these new formulations using advanced evaluation techniques and observations and release

  9. An Aerosol Physical Chemistry Model for the Upper Troposphere

    NASA Technical Reports Server (NTRS)

    Lin, Jin-Sheng

    2001-01-01

    This report is the final report for the Cooperative Agreement NCC2-1000. The tasks outlined in the various proposals are listed with a brief comment as to the research performed. The publications titles are: The effects of particle size and nitric acid uptake on the homogenous freezing of sulfate aerosols; Parameterization of an aerosol physical chemistry model (APCM) for the NH3/H2SO4/HNO3/H2O system at cold temperatures; and The onset, extent and duration of dehydration in the Southern Hemisphere polar vortex.

  10. Comparison of five bacteriophages as models for viral aerosol studies.

    PubMed

    Turgeon, Nathalie; Toulouse, Marie-Josée; Martel, Bruno; Moineau, Sylvain; Duchaine, Caroline

    2014-07-01

    Bacteriophages are perceived to be good models for the study of airborne viruses because they are safe to use, some of them display structural features similar to those of human and animal viruses, and they are relatively easy to produce in large quantities. Yet, only a few studies have investigated them as models. It has previously been demonstrated that aerosolization, environmental conditions, and sampling conditions affect viral infectivity, but viral infectivity is virus dependent. Thus, several virus models are likely needed to study their general behavior in aerosols. The aim of this study was to compare the effects of aerosolization and sampling on the infectivity of five tail-less bacteriophages and two pathogenic viruses: MS2 (a single-stranded RNA [ssRNA] phage of the Leviviridae family), Φ6 (a segmented double-stranded RNA [dsRNA] phage of the Cystoviridae family), ΦX174 (a single-stranded DNA [ssDNA] phage of the Microviridae family), PM2 (a double-stranded DNA [dsDNA] phage of the Corticoviridae family), PR772 (a dsDNA phage of the Tectiviridae family), human influenza A virus H1N1 (an ssRNA virus of the Orthomyxoviridae family), and the poultry virus Newcastle disease virus (NDV; an ssRNA virus of the Paramyxoviridae family). Three nebulizers and two nebulization salt buffers (with or without organic fluid) were tested, as were two aerosol sampling devices, a liquid cyclone (SKC BioSampler) and a dry cyclone (National Institute for Occupational Safety and Health two-stage cyclone bioaerosol sampler). The presence of viruses in collected air samples was detected by culture and quantitative PCR (qPCR). Our results showed that these selected five phages behave differently when aerosolized and sampled. RNA phage MS2 and ssDNA phage ΦX174 were the most resistant to aerosolization and sampling. The presence of organic fluid in the nebulization buffer protected phages PR772 and Φ6 throughout the aerosolization and sampling with dry cyclones. In this

  11. Modelling and evaluation of size-resolved aerosol characteristics in the Eastern Mediterranean during the SUB-AERO project

    NASA Astrophysics Data System (ADS)

    Spyridaki, A.; Lazaridis, M.; Eleftheriadis, K.; Smolik, J.; Mihalopoulos, N.; Aleksandropoulou, V.

    The mesoscale air-quality modelling system UAM-AERO has been applied to study the dynamics of aerosols in the Eastern Mediterranean area. The objective of the current work is to validate the model against extensive field aerosol data for the realistic determination of the aerosol size distribution/chemical composition. The model has been studied against comprehensive aerosol size distribution data during the periods July 2000 and January 2001 at the Eastern Mediterranean area. Comparison of the model results with the field data shows that the model predicts a bimodal size distribution for the aerosol mass, which is in agreement with the experimental data, but underpredicts the total mass during the summer period, whereas the agreement for the total aerosol mass is better during the winter period. The model is capable of reproducing the size distribution characteristics of sulphate, ammonium and nitrate, but discrepancies have occurred in relation to their mass concentration during the period 26-30 July 2000. Discrepancies have also been observed in the determination of the size distribution characteristics of crustal aerosol mass and sea salt. The disagreement between the modelled results and the field data is attributed to uncertainties in the primary aerosol emissions such as sea salt and resuspended dust, and unresolved emissions from sources such as forest fires and Saharan dust episodes. It is evident that the use of the mesoscale model UAM-AERO in the Mediterranean area requires the parallel use of a regional model, which needs to incorporate emissions of Saharan dust and forest fires.

  12. Evaluation of the sectional aerosol microphysics module SALSA implementation in ECHAM5-HAM aerosol-climate model

    NASA Astrophysics Data System (ADS)

    Bergman, T.; Kerminen, V.-M.; Korhonen, H.; Lehtinen, K. J.; Makkonen, R.; Arola, A.; Mielonen, T.; Romakkaniemi, S.; Kulmala, M.; Kokkola, H.

    2011-12-01

    We present the implementation and evaluation of a sectional aerosol microphysics model SALSA within the aerosol-climate model ECHAM5-HAM. This aerosol microphysics module has been designed to be flexible and computationally efficient so that it can be implemented in regional or global scale models. The computational efficiency has been achieved by keeping the number of variables needed to describe the size and composition distribution to the minimum. The aerosol size distribution is described using 20 size sections with 10 size sections in size space which cover diameters ranging from 3 nm to 10 μm divided to three subranges each having distinct optimised process and compound selection. The ability of the module to describe the global aerosol properties was evaluated by comparison against (1) measured continental and marine size distributions, (2) observed variability of continental modal number concentrations, (3) measured sulphate, organic carbon, black carbon and sea salt mass concentrations, (4) observations of AOD and other aerosol optical properties from satellites and AERONET network, (5) global aerosol budgets and concentrations from previous model studies, and (6) model results using M7 which is the default aerosol microphysics module in ECHAM5-HAM. The evaluation shows that the global aerosol properties can be reproduced reasonably well using the coarse resolution of 10 size sections in size space. The simulated global aerosol budgets are within the range of previous studies. Surface concentrations of sea salt, sulphate and carbonaceous species have an annual mean within a factor of five of the observations, while the simulated sea salt concentrations reproduce the observations less accurately and show high variability. Regionally, AOD is in relatively good agreement with the observations (within a factor of two). At mid-latitudes the observed AOD is captured well, while at high-latitudes as well as in some polluted and dust regions the modeled AOD is

  13. Modelling of primary aerosols in the chemical transport model MOCAGE: development and evaluation of aerosol physical parameterizations

    NASA Astrophysics Data System (ADS)

    Sič, B.; El Amraoui, L.; Marécal, V.; Josse, B.; Arteta, J.; Guth, J.; Joly, M.; Hamer, P.

    2014-04-01

    This paper deals with recent improvements to the chemical transport model of Météo-France MOCAGE that consists of updates to different aerosol parameterizations. MOCAGE only contains primary aerosol species. We introduced important changes to the aerosol parameterization concerning emissions, wet deposition and sedimentation. For the emissions, size distribution and wind calculations are modified for desert dust aerosols, and a surface sea temperature dependant source function is introduced for sea salt aerosols. Wet deposition is modified toward a more physically realistic representation by introducing re-evaporation of falling rain and snowfall scavenging, and by changing in-cloud scavenging scheme along with calculations of precipitation cloud cover and rain properties. The sedimentation scheme update includes changes regarding the stability and viscosity calculations. Independent data from satellites (MODIS, SEVIRI), the ground (AERONET), and a model inter-comparison project (AeroCom) is compared with MOCAGE simulations and showed that the introduced changes brought a significant improvement on aerosol representation, properties and global distribution. Emitted quantities of desert dust and sea salt, as well their lifetimes, moved closer towards values of AeroCom estimates and the multi-model average. When comparing the model simulations with MODIS aerosol optical depth (AOD) observations over the oceans, the updated model configuration shows a decrease in the bias (from 0.032 to 0.002) and a better correlation (from 0.062 to 0.322) in terms of the geographical distribution and the temporal variability. The updates corrected a strong positive bias in the sea salt representation at high latitudes (from 0.153 to 0.026), and a negative bias in the desert dust representation in the African dust outflow region (from -0.179 to -0.051). The updates in sedimentation produced a modest difference; the bias with MODIS data from 0.002 in the updated configuration went to

  14. High Resolution Aerosol Modeling: Decadal Changes in Radiative Forcing

    SciTech Connect

    Bergmann, D J; Chuang, C C; Govindasamy, B; Cameron-Smith, P J; Rotman, D A

    2005-02-01

    The Atmospheric Science Division of LLNL has performed high-resolution calculations of direct sulfate forcing using a DOE-provided computer resource at NERSC. We integrated our global chemistry-aerosol model (IMPACT) with the LLNL high-resolution global climate model (horizontal resolution as high as 100 km) to examine the temporal evolution of sulfate forcing since 1950. We note that all previous assessments of sulfate forcing reported in IPCC (2001) were based on global models with coarse spatial resolutions ({approx} 300 km or even coarser). However, the short lifetime of aerosols ({approx} days) results in large spatial and temporal variations of radiative forcing by sulfate. As a result, global climate models with coarse resolutions do not accurately simulate sulfate forcing on regional scales. It requires much finer spatial resolutions in order to address the effects of regional anthropogenic SO{sub 2} emissions on the global atmosphere as well as the effects of long-range transport of sulfate aerosols on the regional climate forcing. By taking advantage of the tera-scale computer resources at NERSC, we simulated the historic direct sulfate forcing at much finer spatial resolutions than ever attempted before. Furthermore, we performed high-resolution chemistry simulations and saved monthly averaged oxidant fields, which will be used in subsequent simulations of sulfate aerosol formation and their radiative impact.

  15. An Aerosolized Brucella spp. Challenge Model for Laboratory Animals

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To characterize the optimal aerosol dosage of Brucella abortus strain 2308 (S2308) and B. melitensis (S16M) in a laboratory animal model of brucellosis, dosages of 10**3 to 10**10 CFU were nebulized to mice. Although tissue weights were minimally influenced, total colony-forming units (CFU) per tis...

  16. Simulating Aerosol Indirect Effects with Improved Aerosol-Cloud- Precipitation Representations in a Coupled Regional Climate Model

    SciTech Connect

    Zhang, Yang; Leung, L. Ruby; Fan, Jiwen

    2016-04-27

    This is a collaborative project among North Carolina State University, Pacific Northwest National Laboratory, and Scripps Institution of Oceanography, University of California at San Diego to address the critical need for an accurate representation of aerosol indirect effect in climate and Earth system models. In this project, we propose to develop and improve parameterizations of aerosol-cloud-precipitation feedbacks in climate models and apply them to study the effect of aerosols and clouds on radiation and hydrologic cycle. Our overall objective is to develop, improve, and evaluate parameterizations to enable more accurate simulations of these feedbacks in high resolution regional and global climate models.

  17. A Novel Tool for Simulating Aerosol-cloud Interactions with a Sectional Model Implemented to a Large-Eddy Simulator

    NASA Astrophysics Data System (ADS)

    Tonttila, J.; Romakkaniemi, S.; Kokkola, H.; Maalick, Z.; Korhonen, H.; Liqing, H.

    2015-12-01

    A new cloud-resolving model setup for studying aerosol-cloud interactions, with a special emphasis on partitioning and wet deposition of semi-volatile aerosol species, is presented. The model is based on modified versions of two well-established model components: the Large-Eddy Simulator (LES) UCLALES, and the sectional aerosol model SALSA, previously employed in the ECHAM climate model family. Implementation of the UCLALES-SALSA is described in detail. As the basis for this work, SALSA has been extended to include a sectional representation of the size distributions of cloud droplets and precipitation. Microphysical processes operating on clouds and precipitation have also been added. Given our main motivation, the cloud droplet size bins are defined according to the dry particle diameter. The droplet wet diameter is solved dynamically through condensation equations, but represents an average droplet diameter inside each size bin. This approach allows for accurate tracking of the aerosol properties inside clouds, but minimizes the computational cost. Since the actual cloud droplet diameter is not fully resolved inside the size bins, processes such as precipitation formation rely on parameterizations. For realistic growth of drizzle drops to rain, which is critical for the aerosol wet deposition, the precipitation size bins are defined according to the actual drop size. With these additions, the implementation of the SALSA model replaces most of the microphysical and thermodynamical components within the LES. The cloud properties and aerosol-cloud interactions simulated by the model are analysed and evaluated against detailed cloud microphysical boxmodel results and in-situ aerosol-cloud interaction observations from the Puijo measurement station in Kuopio, Finland. The ability of the model to reproduce the impacts of wet deposition on the aerosol population is demonstrated.

  18. LES Modeling of Aerosol and Drizzle Effects in Marine Stratocumulus

    DTIC Science & Technology

    2001-09-30

    research is based on the CIMMS LES model of boundary layer stratocumulus clouds with explicit formulation of aerosol and drop size-resolving...rates calculated from the CIMMS explicit microphysics LES model. The errors of parameterized expressions are an order of magnitude less than...framework of the CIMMS LES model where the errors of the parameterization can be assessed in a more realistic setting. The performance of the

  19. Impact of aging mechanism on model simulated carbonaceous aerosols

    PubMed Central

    Huang, Y.; Wu, S.; Dubey, M.K.; French, N. H. F.

    2013-01-01

    Carbonaceous aerosols including organic carbon and black carbon have significant implications for both climate and air quality. In the current global climate or chemical transport models, a fixed hydrophobic-to-hydrophilic conversion lifetime for carbonaceous aerosol (τ) is generally assumed, which is usually around one day. We have implemented a new detailed aging scheme for carbonaceous aerosols in a chemical transport model (GEOS-Chem) to account for both the chemical oxidation and the physical condensation-coagulation effects, where τ is affected by local atmospheric environment including atmospheric concentrations of water vapor, ozone, hydroxyl radical and sulfuric acid. The updated τ exhibits large spatial and temporal variations with the global average (up to 11 km altitude) calculated to be 2.6 days. The chemical aging effects are found to be strongest over the tropical regions driven by the low ozone concentrations and high humidity there. The τ resulted from chemical aging generally decreases with altitude due to increases in ozone concentration and decreases in humidity. The condensation-coagulation effects are found to be most important for the high-latitude areas, in particular the polar regions, where the τ values are calculated to be up to 15 days. When both the chemical aging and condensation-coagulation effects are considered, the total atmospheric burdens and global average lifetimes of BC, black carbon, (OC, organic carbon) are calculated to increase by 9% (3%) compared to the control simulation, with considerable enhancements of BC and OC concentrations in the Southern Hemisphere. Model evaluations against data from multiple datasets show that the updated aging scheme improves model simulations of carbonaceous aerosols for some regions, especially for the remote areas in the Northern Hemisphere. The improvement helps explain the persistent low model bias for carbonaceous aerosols in the Northern Hemisphere reported in literature. Further

  20. MATRIX-VBS (v1.0): implementing an evolving organic aerosol volatility in an aerosol microphysics model

    NASA Astrophysics Data System (ADS)

    Gao, Chloe Y.; Tsigaridis, Kostas; Bauer, Susanne E.

    2017-02-01

    The gas-particle partitioning and chemical aging of semi-volatile organic aerosol are presented in a newly developed box model scheme, where its effect on the growth, composition, and mixing state of particles is examined. The volatility-basis set (VBS) framework is implemented into the aerosol microphysical scheme MATRIX (Multiconfiguration Aerosol TRacker of mIXing state), which resolves mass and number aerosol concentrations and in multiple mixing-state classes. The new scheme, MATRIX-VBS, has the potential to significantly advance the representation of organic aerosols in Earth system models by improving upon the conventional representation as non-volatile particulate organic matter, often also with an assumed fixed size distribution. We present results from idealized cases representing Beijing, Mexico City, a Finnish forest, and a southeastern US forest, and investigate the evolution of mass concentrations and volatility distributions for organic species across the gas and particle phases, as well as assessing their mixing state among aerosol populations. Emitted semi-volatile primary organic aerosols evaporate almost completely in the intermediate-volatility range, while they remain in the particle phase in the low-volatility range. Their volatility distribution at any point in time depends on the applied emission factors, oxidation by OH radicals, and temperature. We also compare against parallel simulations with the original scheme, which represented only the particulate and non-volatile component of the organic aerosol, examining how differently the condensed-phase organic matter is distributed across the mixing states in the model. The results demonstrate the importance of representing organic aerosol as a semi-volatile aerosol, and explicitly calculating the partitioning of organic species between the gas and particulate phases.

  1. MATRIX-VBS (v1.0): Implementing an Evolving Organic Aerosol Volatility in an Aerosol Microphysics Model

    NASA Technical Reports Server (NTRS)

    Gao, Chloe Y.; Tsigaridis, Kostas; Bauer, Susanne E.

    2017-01-01

    The gas-particle partitioning and chemical aging of semi-volatile organic aerosol are presented in a newly developed box model scheme, where its effect on the growth, composition, and mixing state of particles is examined. The volatility-basis set (VBS) framework is implemented into the aerosol microphysical scheme MATRIX (Multiconfiguration Aerosol TRacker of mIXing state), which resolves mass and number aerosol concentrations and in multiple mixing-state classes. The new scheme, MATRIX-VBS, has the potential to significantly advance the representation of organic aerosols in Earth system models by improving upon the conventional representation as non-volatile particulate organic matter, often also with an assumed fixed size distribution. We present results from idealized cases representing Beijing, Mexico City, a Finnish forest, and a southeastern US forest, and investigate the evolution of mass concentrations and volatility distributions for organic species across the gas and particle phases, as well as assessing their mixing state among aerosol populations. Emitted semi-volatile primary organic aerosols evaporate almost completely in the intermediate-volatility range, while they remain in the particle phase in the low-volatility range. Their volatility distribution at any point in time depends on the applied emission factors, oxidation by OH radicals, and temperature. We also compare against parallel simulations with the original scheme, which represented only the particulate and non-volatile component of the organic aerosol, examining how differently the condensed-phase organic matter is distributed across the mixing states in the model. The results demonstrate the importance of representing organic aerosol as a semi-volatile aerosol, and explicitly calculating the partitioning of organic species between the gas and particulate phases.

  2. Trace Gas/Aerosol Interactions and GMI Modeling Support

    NASA Technical Reports Server (NTRS)

    Penner, Joyce E.; Liu, Xiaohong; Das, Bigyani; Bergmann, Dan; Rodriquez, Jose M.; Strahan, Susan; Wang, Minghuai; Feng, Yan

    2005-01-01

    Current global aerosol models use different physical and chemical schemes and parameters, different meteorological fields, and often different emission sources. Since the physical and chemical parameterization schemes are often tuned to obtain results that are consistent with observations, it is difficult to assess the true uncertainty due to meteorology alone. Under the framework of the NASA global modeling initiative (GMI), the differences and uncertainties in aerosol simulations (for sulfate, organic carbon, black carbon, dust and sea salt) solely due to different meteorological fields are analyzed and quantified. Three meteorological datasets available from the NASA DAO GCM, the GISS-II' GCM, and the NASA finite volume GCM (FVGCM) are used to drive the same aerosol model. The global sulfate and mineral dust burdens with FVGCM fields are 40% and 20% less than those with DAO and GISS fields, respectively due to its heavier rainfall. Meanwhile, the sea salt burden predicted with FVGCM fields is 56% and 43% higher than those with DAO and GISS, respectively, due to its stronger convection especially over the Southern Hemispheric Ocean. Sulfate concentrations at the surface in the Northern Hemisphere extratropics and in the middle to upper troposphere differ by more than a factor of 3 between the three meteorological datasets. The agreement between model calculated and observed aerosol concentrations in the industrial regions (e.g., North America and Europe) is quite similar for all three meteorological datasets. Away from the source regions, however, the comparisons with observations differ greatly for DAO, FVGCM and GISS, and the performance of the model using different datasets varies largely depending on sites and species. Global annual average aerosol optical depth at 550 nm is 0.120-0.131 for the three meteorological datasets.

  3. Recent updates in the aerosol model of C-IFS and their impact on skill scores

    NASA Astrophysics Data System (ADS)

    Remy, Samuel; Boucher, Olivier; Hauglustaine, Didier

    2016-04-01

    The Composition-Integrated Forecast System (C-IFS) is a global atmospheric composition forecasting tool, run by ECMWF within the framework of the Copernicus Atmospheric Monitoring Services (CAMS). The aerosol model of C-IFS is a simple bulk scheme that forecasts 5 species: dust, sea-salt, black carbon, organic matter and sulfates. Three bins represent the dust and sea-salt, for the super-coarse, coarse and fine mode of these species (Morcrette et al., 2009). This talk will present recent updates of the aerosol model, and also introduce coming upgrades. It will also present evaluations of these scores against AERONET observations. Next cycle of the C-IFS will include a mass fixer, because the semi-Lagrangian advection scheme used in C-IFS is not mass-conservative. This modification has a negligible impact for most species except for black carbon and organic matter; it allows to close the budgets between sources and sinks in the diagnostics. Dust emissions have been tuned to favor the emissions of large particles, which were under-represented. This brought an overall decrease of the burden of dust aerosol and improved scores especially close to source regions. The biomass-burning aerosol emissions are now emitted at an injection height that is provided by a new version of the Global Fire Assimilation System (GFAS). This brought a small increase in biomass burning aerosols, and a better representation of some large fire events. Lastly, SO2 emissions are now provided by the MACCity dataset instead of and older version of the EDGAR dataset. The seasonal and yearly variability of SO2 emissions are better captured by the MACCity dataset; the use of which brought significant improvements of the forecasts against observations. Upcoming upgrades of the aerosol model of C-IFS consist mainly in the overhaul of the representation of secondary aerosols. Secondary Organic Aerosols (SOA) production will be dynamically estimated by scaling them on CO fluxes. This approach has been

  4. Evaluation of the sectional aerosol microphysics module SALSA implementation in ECHAM5-HAM aerosol-climate model

    NASA Astrophysics Data System (ADS)

    Bergman, T.; Kerminen, V.-M.; Korhonen, H.; Lehtinen, K. J.; Makkonen, R.; Arola, A.; Mielonen, T.; Romakkaniemi, S.; Kulmala, M.; Kokkola, H.

    2012-06-01

    We present the implementation and evaluation of a sectional aerosol microphysics module SALSA within the aerosol-climate model ECHAM5-HAM. This aerosol microphysics module has been designed to be flexible and computationally efficient so that it can be implemented in regional or global scale models. The computational efficiency has been achieved by minimising the number of variables needed to describe the size and composition distribution. The aerosol size distribution is described using 10 size classes with parallel sections which can have different chemical compositions. Thus in total, the module tracks 20 size sections which cover diameters ranging from 3 nm to 10 μm and are divided into three subranges, each with an optimised selection of processes and compounds. The implementation of SALSA into ECHAM5-HAM includes the main aerosol processes in the atmosphere: emissions, removal, radiative effects, liquid and gas phase sulphate chemistry, and the aerosol microphysics. The aerosol compounds treated in the module are sulphate, organic carbon, sea salt, black carbon, and mineral dust. In its default configuration, ECHAM5-HAM treats aerosol size distribution using the modal method. In this implementation, the aerosol processes were converted to be used in a sectional model framework. The ability of the module to describe the global aerosol properties was evaluated by comparing against (1) measured continental and marine size distributions, (2) observed variability of continental number concentrations, (3) measured sulphate, organic carbon, black carbon and sea-salt mass concentrations, (4) observations of aerosol optical depth (AOD) and other aerosol optical properties from satellites and AERONET network, (5) global aerosol budgets and concentrations from previous model studies, and (6) model results using M7, which is the default aerosol microphysics module in ECHAM5-HAM. The evaluation shows that the global aerosol properties can be reproduced reasonably well

  5. A High Elevation Aerosol Manifold Modeling Study and Inter-comparison

    NASA Astrophysics Data System (ADS)

    Hallar, A. G.; Mccubbin, I. B.; Novosselov, I.; Gorder, R.

    2012-12-01

    Via a National Science Foundation grant the Desert Research Institute required professional engineering services to design and model a new fluid dynamics aerosol sampling manifold system to be installed in the renovated Storm Peak Laboratory. The technical objectives include evaluation of the transmission efficiencies for particles with diameters from 3 nanometers to 20 micrometers in the aerosol manifold and to investigate the particulate dispersion and deposition in three different manifold designs currently used throughout the world. Information was collected pertaining to three highly regarded atmospheric aerosol manifolds. The following aerosol manifolds were considered as models: 1. DOE ASR design used throughout the world (e.g. Barrow, Alaska). 2. The aerosol manifold used at the Swiss high elevation site, Jungfraujoch, located at 3.5 km. 3. Current Storm Peak Laboratory aerosol manifold. Based on all available information, DRI assimilated 3-D CAD drawings of these three manifolds. Enertechnix, Inc (http://www.enertechnix.com) was identified by DRI as having the appropriate skills and expertise to perform the Computational Fluid Dynamic (CFD) modeling required for this project. Enertechnix Inc. has completed initial CFD modeling of the three manifold discussed above. The following results will be presented. Transient CFD simulations of the inlets were performed for the wind speed range of 2.5-15 m/s in 3-dimentional numerical wind tunnel at a sampling rate of 1000 lmp. The transmission efficiencies for these inlets were evaluated for particles in 10 nm-20um range. Two different turbulence models (k-epsilon and detached eddy simulations) were used, and the effects of particle - turbulence coupling were examined. The modeling results show that for all three inlets transmission decreases with increase of particle size, due to particle inertial impaction on the inner walls of the inlets. Additionally, the transmission efficiency decreases at higher wind speeds

  6. Separating dynamical and microphysical impacts of aerosols on deep convection applying piggybacking methodology

    NASA Astrophysics Data System (ADS)

    Grabowski, Wojciech W.

    2016-04-01

    Formation and growth of cloud and precipitation particles ("cloud microphysics") affect cloud dynamics and such macroscopic cloud field properties as the mean surface rainfall, cloud cover, and liquid/ice water paths. Traditional approaches to investigate the impacts involve parallel simulations with different microphysical schemes or with different scheme parameters (such as the assumed droplet/ice concentration for single-moment bulk schemes or the assumed CCN/IN concentration for double-moment schemes). Such methodologies are not reliable because of the natural variability of a cloud field that is affected by the feedback between cloud microphysics and cloud dynamics. In a nutshell, changing the cloud microphysics leads to a different realization of the cloud-scale flow, and separating dynamical and microphysical impacts is cumbersome. A novel modeling methodology, referred to as the microphysical piggybacking, was recently developed to separate purely microphysical effects from the impact on the dynamics. The main idea is to use two sets of thermodynamic variables driven by two microphysical schemes or by the same scheme with different scheme parameters. One set is coupled to the dynamics and drives the simulation, and the other set piggybacks the simulated flow, that is, it responds to the simulated flow but does not affect it. By switching the sets (i.e., the set driving the simulation becomes the piggybacking one, and vice versa), the impact on the cloud dynamics can be isolated from purely microphysical effects. Application of this methodology to the daytime deep convection development over land based on the observations during the Large-scale Biosphere-Atmosphere (LBA) field project in Amazonia will be discussed applying single-moment and double-moment bulk microphysics schemes. We show that the new methodology documents a small indirect aerosol impact on convective dynamics, and a strong microphysical effect. These results question the postulated strong

  7. Modelling the direct effect of aerosols in the solar near-infrared on a planetary scale

    NASA Astrophysics Data System (ADS)

    Hatzianastassiou, N.; Matsoukas, C.; Fotiadi, A.; Drakakis, E.; Stackhouse, P. W., Jr.; Koepke, P.; Pavlakis, K. G.; Hatzidimitriou, D.; Vardavas, I.

    2006-09-01

    We used a spectral radiative transfer model to compute the direct radiative effect (DRE) of natural plus anthropogenic aerosols in the solar near-infrared (IR), between 0.85-10 µm, namely, their effect on the outgoing near-IR radiation at the top of atmosphere (TOA, ΔFTOA), on the atmospheric absorption of near-IR radiation (ΔFatmab) and on the surface downward and absorbed near-IR radiation (ΔFsurf, and ΔFsurfnet, respectively). The computations were performed on a global scale (over land and ocean) under all-sky conditions, using spectral aerosol optical properties taken from the Global Aerosol Data Set (GADS) supplemented by realistic data for the rest of surface and atmospheric parameters. The computed aerosol DRE, averaged over the 12-year period 1984-1995 for January and July, shows that aerosols produce a planetary cooling by increasing the scattered near-IR radiation back to space (by up to 6 Wm-2), they warm the atmosphere (by up to 7 Wm-2) and cool the surface (by up to 12 Wm-2). However, they can also slightly warm the Earth-atmosphere system or cool the atmosphere (by less than 1 Wm-2) over limited areas. The magnitude of the near-IR aerosol DRE is smaller than that of the combined ultraviolet (UV) and visible DRE, but it is still energetically important, since it contributes to the total shortwave (SW) DRE by 22-31%. On a global mean basis, the DREs ΔFTOA, ΔFatmab, ΔFsurf, and ΔFsurfnet are equal to about 0.48, 0.37, -1.03 and -0.85 Wm-2, i.e. their magnitude is similar to that of climate forcing associated with increasing concentrations of greenhouse gases. The aerosol induced near-IR surface cooling combined with the atmospheric warming, affects the thermal dynamics of the Earth-atmosphere system, by increasing the atmospheric stability, decreasing thus cloud formation, and precipitation, especially over desertification threatened regions such as the Mediterranean basin. This, together with the fact that the sign of near-IR aerosol DRE is

  8. On the relationship between aerosol model uncertainty and radiative forcing uncertainty

    PubMed Central

    Reddington, Carly L.; Carslaw, Kenneth S.

    2016-01-01

    The largest uncertainty in the historical radiative forcing of climate is caused by the interaction of aerosols with clouds. Historical forcing is not a directly measurable quantity, so reliable assessments depend on the development of global models of aerosols and clouds that are well constrained by observations. However, there has been no systematic assessment of how reduction in the uncertainty of global aerosol models will feed through to the uncertainty in the predicted forcing. We use a global model perturbed parameter ensemble to show that tight observational constraint of aerosol concentrations in the model has a relatively small effect on the aerosol-related uncertainty in the calculated forcing between preindustrial and present-day periods. One factor is the low sensitivity of present-day aerosol to natural emissions that determine the preindustrial aerosol state. However, the major cause of the weak constraint is that the full uncertainty space of the model generates a large number of model variants that are equally acceptable compared to present-day aerosol observations. The narrow range of aerosol concentrations in the observationally constrained model gives the impression of low aerosol model uncertainty. However, these multiple “equifinal” models predict a wide range of forcings. To make progress, we need to develop a much deeper understanding of model uncertainty and ways to use observations to constrain it. Equifinality in the aerosol model means that tuning of a small number of model processes to achieve model−observation agreement could give a misleading impression of model robustness. PMID:26848136

  9. Optical modeling of aerosol extinction for remote sensing in the marine environment

    NASA Astrophysics Data System (ADS)

    Kaloshin, G. A.

    2013-05-01

    A microphysical model is presented for the surface layer marine and coastal atmospheric aerosols that is based on long-term observations of size distributions for 0.01-100 μm particles in different geographic sites. The fundamental feature of the model is a parameterization of amplitudes and widths for aerosol modes of the aerosol size distribution function (ASDF) as functions of fetch and wind speed. The shape of the ASDF and its dependence on meteorological parameters, altitudes above sea level (H), fetch (X), wind speed (U) and relative humidity (RH) are investigated. The spectral profiles of the aerosol extinction coefficients calculated by MaexPro (Marine Aerosol Extinction Profiles) are in good agreement with observational data and the numerical results obtained from the Navy Aerosol Model (NAM) and the Advanced Navy Aerosol Model (ANAM). Moreover, MaexPro was found to be an accurate and reliable tool for investigation of the optical properties of atmospheric aerosols.

  10. Modeling the Role of Alkanes, Polycyclic Aromatic Hydrocarbons, and Their Oligomers in Secondary Organic Aerosol Formation

    EPA Science Inventory

    A computationally efficient method to treat secondary organic aerosol (SOA) from various length and structure alkanes as well as SOA from polycyclic aromatic hydrocarbons (PAHs) is implemented in the Community Multiscale Air Quality (CMAQ) model to predict aerosol concentrations ...

  11. Lessons Learned About Organic Aerosol Formation in the Southeast U.S. Using Observations and Modeling

    EPA Science Inventory

    Isoprene emitted by vegetation is an important precursor of secondary organic aerosol (SOA). In this work, modeling of isoprene SOA via heterogeneous uptake is explored and compared to observations from the Southern Oxidant and Aerosol Study (SOAS).

  12. Effective Henry's Law constant measurements for glyoxal in model aerosols containing sulfate

    NASA Astrophysics Data System (ADS)

    Kampf, C. J.; Waxman, E.; Slowik, J. G.; Dommen, J.; Prevot, A. S.; Noziere, B.; Hoffmann, T.; Volkamer, R.

    2011-12-01

    Traditional models represent secondary organic aerosol (SOA) formation based on the gas-phase oxidation of a limited set of precursor molecules. However, these models tend to under-estimate the amounts and degree of oxygenation of actual SOA, indicating missing processes. One such source that has become increasingly important in recent years is glyoxal (CHOCHO, the smallest alpha-dicarbonyl). Unlike traditional SOA precursors, glyoxal forms SOA by partitioning to the aqueous phase according to Henry's Law. This work presents an analysis of Henry's Law constants for glyoxal uptake to laboratory-generated aerosols in a dynamically coupled gas-aerosol system. We combine CU LED-CE-DOAS measurements of gas-phase glyoxal with online HR-Tof-AMS and time-resolved HPLC ESI MS/MS particle-phase measurements to characterize the time resolved evolution of glyoxal partitioning, and relate molecular-specific measurements to AMS mass spectra. The experiments were performed in the simulation chamber facility at PSI, Switzerland, and investigate ammonium sulfate (AS), and mixed AS / fulvic acid seed aerosols under relative humidity conditions ranging from 50 to 85% RH. The Henry's Law and effective Henry's Law constants are compared with other values reported in the literature.

  13. Effective Henry's Law constant measurements for glyoxal in model aerosols containing sulfate

    NASA Astrophysics Data System (ADS)

    Kampf, C.; Waxman, E.; Slowik, J.; Dommen, J.; Prevot, A.; Baltensperger, U.; Noziere, B.; Hoffmann, T.; Volkamer, R.

    2012-04-01

    Traditional models represent secondary organic aerosol (SOA) formation based on the gas-phase oxidation of a limited set of precursor molecules. However, these models tend to under-estimate the amounts and degree of oxygenation of actual SOA, indicating missing processes. One such source that has become increasingly important in recent years is glyoxal (CHOCHO, the smallest alpha-dicarbonyl). Unlike traditional SOA precursors, glyoxal forms SOA by partitioning to the aqueous phase according to Henry's Law. This work presents an analysis of Henry's Law constants for glyoxal uptake to laboratory-generated aerosols in a dynamically coupled gas-aerosol system. We combine CU LED-CE-DOAS measurements of gas-phase glyoxal with online HR-Tof-AMS and time-resolved HPLC ESI MS/MS particle-phase measurements to characterize the time resolved evolution of glyoxal partitioning, and relate molecular-specific measurements to AMS mass spectra. The experiments were performed in the simulation chamber facility at PSI, Switzerland, and investigate ammonium sulfate (AS), and mixed AS / fulvic acid seed aerosols under relative humidity conditions ranging from 50 to 85% RH. The Henry's Law and effective Henry's Law constants are compared with other values reported in the literature.

  14. Breaker zone aerosol dynamics in the southern Baltic Sea

    SciTech Connect

    Zielinski, T.; Zielinski, A.

    1994-12-31

    This paper presents the results of lidar based investigations of aerosol concentrations and their size distributions over the breaker zones. The measurements were carried out under various weather conditions over breaker zones of the Gulf of Gdansk (1992) and from a station on the open Baltic Sea (International Experiment BAEX in 1993).

  15. A Model Simulation of Pinatubo Volcanic Aerosols in the Stratosphere

    NASA Technical Reports Server (NTRS)

    Zhao , Jing-xia; Turco, Richard P.; Toon, Owen B.

    1995-01-01

    A one-dimensional, time-dependent model is used to study the chemical, microphysical, and radiative properties of volcanic aerosols produced by the Mount Pinatubo eruption on June 15, 1991. Our model treats gas-phase sulfur photochemistry, gas-to-particle conversion of sulfur, and the microphysics of sulfate aerosols and ash particles under stratospheric conditions. The dilution and diffusion of the volcanic eruption clouds are also accounted for in these conditions. Heteromolecular homogeneous and heterogeneous binary H2SO4/H2O nucleation, acid and water condensational growth, coagulation, and gravitational sedimentation are treated in detail in the model. Simulations suggested that after several weeks, the volcanic cloud was composed mainly of sulfuric acid/water droplets produced in situ from the SO2 emissions. The large amounts of SO2 (around 20 Mt) injected into the stratosphere by the Pinatubo eruption initiated homogeneous nucleation which generated a high concentration of small H2SO4/H2O droplets. These newly formed particles grew rapidly by condensation and coagulation in the first few months and then reach their stabilized sizes with effective radii in a range between 0.3 and 0.5 micron approximately one-half year after the eruption. The predicted volcanic cloud parameters reasonably agree with measurements in term of the vertical distribution and lifetime of the volcanic aerosols, their basic microphysical structures (e.g., size distribution, concentration, mass ratio, and surface area) and radiative properties. The persistent volcanic aerosols can produce significant anomalies in the radiation field, which have important climatic consequences. The large enhancement in aerosol surface area can result in measurable global stratospheric ozone depletion.

  16. Modeling the Explicit Chemistry of Anthropogenic and Biogenic Organic Aerosols

    SciTech Connect

    Madronich, Sasha

    2015-12-09

    The atmospheric burden of Secondary Organic Aerosols (SOA) remains one of the most important yet uncertain aspects of the radiative forcing of climate. This grant focused on improving our quantitative understanding of SOA formation and evolution, by developing, applying, and improving a highly detailed model of atmospheric organic chemistry, the Generation of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) model. Eleven (11) publications have resulted from this grant.

  17. Sensitivity of Remote Aerosol Distributions to Representation of Cloud-Aerosol Interactions in a Global Climate Model

    SciTech Connect

    Wang, Hailong; Easter, Richard C.; Rasch, Philip J.; Wang, Minghuai; Liu, Xiaohong; Ghan, Steven J.; Qian, Yun; Yoon, Jin-Ho; Ma, Po-Lun; Vinoj, V.

    2013-06-05

    Many global aerosol and climate models, including the widely used Community Atmosphere Model version 5 (CAM5), have large biases in predicting aerosols in remote regions such as upper troposphere and high latitudes. In this study, we conduct CAM5 sensitivity simulations to understand the role of key processes associated with aerosol transformation and wet removal affecting the vertical and horizontal long-range transport of aerosols to the remote regions. Improvements are made to processes that are currently not well represented in CAM5, which are guided by surface and aircraft measurements together with results from a multi-scale aerosol-climate model (PNNL-MMF) that explicitly represents convection and aerosol-cloud interactions at cloud-resolving scales. We pay particular attention to black carbon (BC) due to its importance in the Earth system and the availability of measurements. We introduce into CAM5 a new unified scheme for convective transport and aerosol wet removal with explicit aerosol activation above convective cloud base. This new implementation reduces the excessive BC aloft to better simulate observed BC profiles that show decreasing mixing ratios in the mid- to upper-troposphere. After implementing this new unified convective scheme, we examine wet removal of submicron aerosols that occurs primarily through cloud processes. The wet removal depends strongly on the sub-grid scale liquid cloud fraction and the rate of conversion of liquid water to precipitation. These processes lead to very strong wet removal of BC and other aerosols over mid- to high latitudes during winter months. With our improvements, the Arctic BC burden has a10-fold (5-fold) increase in the winter (summer) months, resulting in a much better simulation of the BC seasonal cycle as well. Arctic sulphate and other aerosol species also increase but to a lesser extent. An explicit treatment of BC aging with slower aging assumptions produces an additional 30-fold (5-fold) increase in

  18. Present-day to 21st century projections of secondary organic aerosol (SOA) from a global climate-aerosol model with an explicit SOA formation scheme

    NASA Astrophysics Data System (ADS)

    Lin, G.; Penner, J. E.; Zhou, C.

    2014-12-01

    Secondary organic aerosol (SOA) has been shown to be an important component of non-refractory submicron aerosol in the atmosphere. The presence of SOA can influence the earth's radiative balance by contributing to the absorption and scattering of radiation and by altering the properties of clouds. Globally, a large fraction of SOA originates from biogenic volatile organic compounds (BVOCs), emissions of which depend on vegetation cover and climate. Temperature, CO2 concentration, and land use and land cover change have been shown to be major drivers of global isoprene emission changes in future climates. Additionally, the SOA concentration in the atmosphere not only depends on BVOC emissions, but is also controlled by anthropogenic emissions, temperature, precipitation and the oxidative capacity of the atmosphere. To project the change in SOA concentrations in the future requires a model that fully couples a BVOC emission model that represents these BVOC emission drivers, together with a sophisticated atmospheric model of SOA formation and properties. Recent studies have suggested that traditional parameterized SOA formation mechanisms that are tuned to fit smog chamber data do not fully account for the complexity and dynamics of real SOA system, calling into the question of the validity and completeness of previous SOA projections. In this study, we investigate the response of SOA mass to future physical climate change, to land cover and land use change, to changes in BVOCs emissions, and to changes in anthropogenic aerosol and gas species emissions for the year 2100, utilizing a global climate-aerosol model (CAM5-IMPACT): the NCAR Community Atmospheric Model (CAM5) coupled with a global aerosol model (IMPACT). The IMPACT model has sophisticated detailed process-based mechanisms describing aerosol microphysics and SOA formation through both gas phase and multiphase reactions. We perform sensitivity tests to isolate the relative roles of individual global change

  19. Evaluation of Aerosol-Cloud Interactions in GISS ModelE Using ASR Observations

    NASA Astrophysics Data System (ADS)

    de Boer, G.; Menon, S.; Bauer, S. E.; Toto, T.; Bennartz, R.; Cribb, M.

    2011-12-01

    The impacts of aerosol particles on clouds continue to rank among the largest uncertainties in global climate simulation. In this work we assess the capability of the NASA GISS ModelE, coupled to MATRIX aerosol microphysics, in correctly representing warm-phase aerosol-cloud interactions. This evaluation is completed through the analysis of a nudged, multi-year global simulation using measurements from various US Department of Energy sponsored measurement campaigns and satellite-based observations. Campaign observations include the Aerosol Intensive Operations Period (Aerosol IOP) and Routine ARM Arial Facility Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) at the Southern Great Plains site in Oklahoma, the Marine Stratus Radiation, Aerosol, and Drizzle (MASRAD) campaign at Pt. Reyes, California, and the ARM mobile facility's 2008 deployment to China. This combination of datasets provides a variety of aerosol and atmospheric conditions under which to test ModelE parameterizations. In addition to these localized comparisons, we provide the results of global evaluations completed using measurements derived from satellite remote sensors. We will provide a basic overview of simulation performance, as well as a detailed analysis of parameterizations relevant to aerosol indirect effects.

  20. Spatial distributions and seasonal cycles of aerosol climate effects in India seen in a global climate-aerosol model

    NASA Astrophysics Data System (ADS)

    Henriksson, S. V.; Pietikäinen, J.-P.; Hyvärinen, A.-P.; Räisänen, P.; Kupiainen, K.; Tonttila, J.; Hooda, R.; Lihavainen, H.; O'Donnell, D.; Backman, L.; Klimont, Z.; Laaksonen, A.

    2014-09-01

    Climate-aerosol interactions in India are studied by employing the global climate-aerosol model ECHAM5-HAM and the GAINS inventory for anthropogenic aerosol emissions. Model validation is done for black carbon surface concentrations in Mukteshwar and for features of the monsoon circulation. Seasonal cycles and spatial distributions of radiative forcing and the temperature and rainfall responses are presented for different model setups. While total aerosol radiative forcing is strongest in the summer, anthropogenic forcing is considerably stronger in winter than in summer. Local seasonal temperature anomalies caused by aerosols are mostly negative with some exceptions, e.g., parts of northern India in March-May. Rainfall increases due to the elevated heat pump (EHP) mechanism and decreases due to solar dimming mechanisms (SDMs) and the relative strengths of these effects during different seasons and for different model setups are studied. Aerosol light absorption does increase rainfall in northern India, but effects due to solar dimming and circulation work to cancel the increase. The total aerosol effect on rainfall is negative for northern India in the months of June-August, but during March-May the effect is positive for most model setups. These differences between responses in different seasons might help converge the ongoing debate on the EHPs and SDMs. Due to the complexity of the problem and known or potential sources for error and bias, the results should be interpreted cautiously as they are completely dependent on how realistic the model is. Aerosol-rainfall correlations and anticorrelations are shown not to be a reliable sole argument for deducing causality.

  1. Climate effects of anthropogenic aerosols over East Asia based on modeling study

    NASA Astrophysics Data System (ADS)

    Mukai, Makiko

    The increasing emission of anthropogenic aerosols causes serious air pollution episodes and various effects on the climate by the aerosols interacting with the radiation budget by directly absorbing and scattering the solar radiation, and by them indirectly modifying the optical properties and lifetimes of clouds. In East Asia anthropogenic aerosol concentrations are rapidly increasing. It is therefore necessary to evaluate the sensitivity of anthropogenic aerosols upon the radiative forcing in this region. For this purpose we utilize an atmospheric general circulation model (AGCM) with an aerosol transport and radiation model and an ocean mixed-layer model. The model in this study was a three-dimensional aerosol transport-radiation model (SPRINTARS), driven by the AGCM developed by CCSR (Center for Climate System Research), NIES (National Institute for Environmental Studies), and FRCGC (Frontier Research Center for Global Change). This model incorporates sulfate, carbonaceous, sea salt, and mineral dust aerosols, the first three of which are assumed to acts as cloud condensation nuclei that generate cloud droplets whose number increases with the number of nuclei. We assumed sulfate and carbonaceous aerosol from fuel burning for anthropogenic aerosol. And the model simulations of equilibrium experiments were performed to investigate the impact of anthropogenic aerosols based on present-day emission data and the preindustrial-era emission data. Our simulation results showed that copious anthropogenic aerosol loading causes significant decrease in the surface downward shortwave radiation flux (SDSWRF), which indicates that a direct effect of aerosols has the greatest influence on the surface radiation. It is found from our model simulations that low-level clouds increase but convective clouds decrease due to reduced convective activity caused by surface cooling when anthropogenic aerosol increases. It was also found that the contributions of aerosols to the radiation

  2. Early growth dynamical implications for the steerability of stratospheric solar radiation management via sulfur aerosol particles

    NASA Astrophysics Data System (ADS)

    Benduhn, François; Schallock, Jennifer; Lawrence, Mark G.

    2016-09-01

    Aerosol growth dynamics may have implications for the steerability of stratospheric solar radiation management via sulfur particles. This paper derives a set of critical initial growth conditions that are analyzed as a function of two key parameters: the initial concentration of the injected sulfuric acid and its dilution rate with the surrounding air. Based upon this analysis, early aerosol growth dynamical regimes may be defined and classified in terms of their likelihood to serve as candidates for the controlled generation of a radiatively effective aerosol. Our results indicate that the regime that fulfills all critical conditions would require that airplane turbines be used to provide sufficient turbulence. The regime's parameter space is narrow and related to steep gradients, thus pointing to potential fine tuning requirements. More research, development, and testing would be required to refine our findings and determine their global-scale implications.

  3. Micro-capillary aerosol focusing device: theoretical modeling, experimental verification, and device fabrication.

    NASA Astrophysics Data System (ADS)

    Hoey, Justin; Akhatov, Iskander; Swenson, Orven; Schulz, Doug

    2007-11-01

    A theoretical model for the focusing of aerosol particles in a linearly-varying micro-capillary with a diameter on the order of 100 microns is presented. This theoretical model is experimentally verified by visualizing an aerosol beam of silver-ink aerosol particles of approximately 1 micron in diameter emitted from a micro-capillary. Additional validation is presented in the deposited lines where linewidth is a function of aerosol beamwidth. From the theoretical model a new design for the focusing of aerosol particles is developed, physically produced, and experimentally validated. The new device will be implemented in the areas of high frequency RFID manufacturing, and the semiconductor industry.

  4. Interfacing the NRL 1-D High Vertical Resolution Aerosol Model with COAMPS

    DTIC Science & Technology

    2016-06-13

    TERM GOALS Identify, understand and quantify all the physical processes that govern the aerosols in the marine environment and develop a...size and composition distributions are required. Many of the aerosol source, sink and transformation processes are highly dependent on meteorological...parameters such as wind speed, humidity profile, clouds, precipitation scavenging, etc. The NRL 1-D aerosol- processes model includes all these

  5. simpleGAMMA - a reduced model of secondary organic aerosol formation in the aqueous aerosol phase (aaSOA)

    NASA Astrophysics Data System (ADS)

    Woo, J. L.; McNeill, V. F.

    2015-01-01

    There is increasing evidence that the uptake and aqueous processing of water-soluble volatile organic compounds (VOCs) by wet aerosols or cloud droplets is an important source of secondary organic aerosol (SOA). We recently developed GAMMA (Gas-Aerosol Model for Mechanism Analysis), a zero-dimensional kinetic model that couples gas-phase and detailed aqueous-phase atmospheric chemistry for speciated prediction of SOA and organosulfate formation in cloudwater or aqueous aerosols. Results from GAMMA simulations of SOA formation in aerosol water (McNeill et al., 2012) indicate that it is dominated by two pathways: isoprene epoxydiol (IEPOX) uptake followed by ring-opening chemistry (under low-NOx conditions) and glyoxal uptake. This suggested that it is possible to model the majority of aqueous aerosol phase SOA mass using a highly simplified reaction scheme. We have therefore developed a reduced version of GAMMA, simpleGAMMA. Close agreement in predicted aaSOA mass is observed between simpleGAMMA and GAMMA under all conditions tested (between pH 1-4 and RH 40-80%) after 12 h of simulation. simpleGAMMA is computationally efficient and suitable for coupling with larger-scale atmospheric chemistry models.

  6. Equivalent Dynamic Models.

    PubMed

    Molenaar, Peter C M

    2017-02-16

    Equivalences of two classes of dynamic models for weakly stationary multivariate time series are discussed: dynamic factor models and autoregressive models. It is shown that exploratory dynamic factor models can be rotated, yielding an infinite set of equivalent solutions for any observed series. It also is shown that dynamic factor models with lagged factor loadings are not equivalent to the currently popular state-space models, and that restriction of attention to the latter type of models may yield invalid results. The known equivalent vector autoregressive model types, standard and structural, are given a new interpretation in which they are conceived of as the extremes of an innovating type of hybrid vector autoregressive models. It is shown that consideration of hybrid models solves many problems, in particular with Granger causality testing.

  7. Assessing the Dynamics of Organic Aerosols over the North Atlantic Ocean

    PubMed Central

    Kasparian, Jérôme; Hassler, Christel; Ibelings, Bas; Berti, Nicolas; Bigorre, Sébastien; Djambazova, Violeta; Gascon-Diez, Elena; Giuliani, Grégory; Houlmann, Raphaël; Kiselev, Denis; de Laborie, Pierric; Le, Anh-Dao; Magouroux, Thibaud; Neri, Tristan; Palomino, Daniel; Pfändler, Stéfanie; Ray, Nicolas; Sousa, Gustavo; Staedler, Davide; Tettamanti, Federico; Wolf, Jean-Pierre; Beniston, Martin

    2017-01-01

    The influence of aerosols on climate is highly dependent on the particle size distribution, concentration, and composition. In particular, the latter influences their ability to act as cloud condensation nuclei, whereby they impact cloud coverage and precipitation. Here, we simultaneously measured the concentration of aerosols from sea spray over the North Atlantic on board the exhaust-free solar-powered vessel “PlanetSolar”, and the sea surface physico-chemical parameters. We identified organic-bearing particles based on individual particle fluorescence spectra. Organic-bearing aerosols display specific spatio-temporal distributions as compared to total aerosols. We propose an empirical parameterization of the organic-bearing particle concentration, with a dependence on water salinity and sea-surface temperature only. We also show that a very rich mixture of organic aerosols is emitted from the sea surface. Such data will certainly contribute to providing further insight into the influence of aerosols on cloud formation, and be used as input for the improved modeling of aerosols and their role in global climate processes. PMID:28361985

  8. Assessing the Dynamics of Organic Aerosols over the North Atlantic Ocean.

    PubMed

    Kasparian, Jérôme; Hassler, Christel; Ibelings, Bas; Berti, Nicolas; Bigorre, Sébastien; Djambazova, Violeta; Gascon-Diez, Elena; Giuliani, Grégory; Houlmann, Raphaël; Kiselev, Denis; de Laborie, Pierric; Le, Anh-Dao; Magouroux, Thibaud; Neri, Tristan; Palomino, Daniel; Pfändler, Stéfanie; Ray, Nicolas; Sousa, Gustavo; Staedler, Davide; Tettamanti, Federico; Wolf, Jean-Pierre; Beniston, Martin

    2017-03-31

    The influence of aerosols on climate is highly dependent on the particle size distribution, concentration, and composition. In particular, the latter influences their ability to act as cloud condensation nuclei, whereby they impact cloud coverage and precipitation. Here, we simultaneously measured the concentration of aerosols from sea spray over the North Atlantic on board the exhaust-free solar-powered vessel "PlanetSolar", and the sea surface physico-chemical parameters. We identified organic-bearing particles based on individual particle fluorescence spectra. Organic-bearing aerosols display specific spatio-temporal distributions as compared to total aerosols. We propose an empirical parameterization of the organic-bearing particle concentration, with a dependence on water salinity and sea-surface temperature only. We also show that a very rich mixture of organic aerosols is emitted from the sea surface. Such data will certainly contribute to providing further insight into the influence of aerosols on cloud formation, and be used as input for the improved modeling of aerosols and their role in global climate processes.

  9. Computational fluid dynamics (CFD) simulations of aerosol in a U-shaped steam generator tube

    NASA Astrophysics Data System (ADS)

    Longmire, Pamela

    To quantify primary side aerosol retention, an Eulerian/Lagrangian approach was used to investigate aerosol transport in a compressible, turbulent, adiabatic, internal, wall-bounded flow. The ARTIST experimental project (Phase I) served as the physical model replicated for numerical simulation. Realizable k-epsilon and standard k-o turbulence models were selected from the computational fluid dynamics (CFD) code, FLUENT, to provide the Eulerian description of the gaseous phase. Flow field simulation results exhibited: (a) onset of weak secondary flow accelerated at bend entrance towards the inner wall; (b) flow separation zone development on the convex wall that persisted from the point of onset; (c) centrifugal force concentrated high velocity flow in the direction of the concave wall; (d) formation of vortices throughout the flow domain resulted from rotational (Dean-type) flow; (e) weakened secondary flow assisted the formation of twin vortices in the outflow cross section; and (f) perturbations induced by the bend influenced flow recovery several pipe diameters upstream of the bend. These observations were consistent with those of previous investigators. The Lagrangian discrete random walk model, with and without turbulent dispersion, simulated the dispersed phase behavior, incorrectly. Accurate deposition predictions in wall-bounded flow require modification of the Eddy Impaction Model (EIM). Thus, to circumvent shortcomings of the EIM, the Lagrangian time scale was changed to a wall function and the root-mean-square (RMS) fluctuating velocities were modified to account for the strong anisotropic nature of flow in the immediate vicinity of the wall (boundary layer). Subsequent computed trajectories suggest a precision that ranges from 0.1% to 0.7%, statistical sampling error. The aerodynamic mass median diameter (AMMD) at the inlet (5.5 mum) was consistent with the ARTIST experimental findings. The geometric standard deviation (GSD) varied depending on the

  10. Preliminary Results from an Assimilation of TOMS Aerosol Observations Into the GOCART Model

    NASA Technical Reports Server (NTRS)

    daSilva, Arlindo; Weaver, Clark J.; Ginoux, Paul; Torres, Omar; Einaudi, Franco (Technical Monitor)

    2000-01-01

    At NASA Goddard we are developing a global aerosol data assimilation system that combines advances in remote sensing and modeling of atmospheric aerosols. The goal is to provide high resolution, 3-D aerosol distributions to the research community. Our first step is to develop a simple assimilation system for Saharan mineral aerosol. The Goddard Chemistry and Aerosol Radiation model (GOCART) provides accurate 3-D mineral aerosol size distributions that compare well with TOMS satellite observations. Surface, mobilization, wet and dry deposition, convective and long-range transport are all driven by assimilated fields from the Goddard Earth Observing System Data Assimilation System, GEOS-DAS. Our version of GOCART transports sizes from.08-10 microns and only simulates Saharan dust. TOMS radiance observations in the ultra violet provide information on the mineral and carbonaceous aerosol fields. We use two main observables in this study: the TOMS aerosol index (AI) which is directly related to the ratio of the 340 and 380 radiances and the 380 radiance. These are sensitive to the aerosol optical thickness, the single scattering albedo and the height of the aerosol layer. The Goddard Aerosol Assimilation System (GAAS) uses the Data Assimilation Office's Physical-space Statistical Analysis System (PSAS) to combine TOMS observations and GOCART model first guess fields. At this initial phase we only assimilate observations into the the GOCART model over regions of Africa and the Atlantic where mineral aerosols dominant and carbonaceous aerosols are minimal, Our preliminary results during summer show that the assimilation with TOMS data modifies both the aerosol mass loading and the single scattering albedo. Assimilated aerosol fields will be compared with assimilated aerosol fields from GOCART and AERONET observations over Cape Verde.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

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

    SciTech Connect

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

    2016-08-22

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

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

    SciTech Connect

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

    2016-08-22

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

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

    DOE PAGES

    Fast, Jerome D.; Berg, Larry K.; Zhang, Kai; ...

    2016-08-22

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

  15. Aerosol kinetic code "AERFORM": Model, validation and simulation results

    NASA Astrophysics Data System (ADS)

    Gainullin, K. G.; Golubev, A. I.; Petrov, A. M.; Piskunov, V. N.

    2016-06-01

    The aerosol kinetic code "AERFORM" is modified to simulate droplet and ice particle formation in mixed clouds. The splitting method is used to calculate condensation and coagulation simultaneously. The method is calibrated with analytic solutions of kinetic equations. Condensation kinetic model is based on cloud particle growth equation, mass and heat balance equations. The coagulation kinetic model includes Brownian, turbulent and precipitation effects. The real values are used for condensation and coagulation growth of water droplets and ice particles. The model and the simulation results for two full-scale cloud experiments are presented. The simulation model and code may be used autonomously or as an element of another code.

  16. Effects of atmospheric dynamics and aerosols on the fraction of supercooled water clouds

    NASA Astrophysics Data System (ADS)

    Li, Jiming; Lv, Qiaoyi; Zhang, Min; Wang, Tianhe; Kawamoto, Kazuaki; Chen, Siyu; Zhang, Beidou

    2017-02-01

    Based on 8 years of (January 2008-December 2015) cloud phase information from the GCM-Oriented Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) Cloud Product (GOCCP), aerosol products from CALIPSO and meteorological parameters from the ERA-Interim products, the present study investigates the effects of atmospheric dynamics on the supercooled liquid cloud fraction (SCF) during nighttime under different aerosol loadings at global scale to better understand the conditions of supercooled liquid water gradually transforming to ice phase. Statistical results indicate that aerosols' effect on nucleation cannot fully explain all SCF changes, especially in those regions where aerosols' effect on nucleation is not a first-order influence (e.g., due to low ice nuclei aerosol frequency). By performing the temporal and spatial correlations between SCFs and different meteorological factors, this study presents specifically the relationship between SCF and different meteorological parameters under different aerosol loadings on a global scale. We find that the SCFs almost decrease with increasing of aerosol loading, and the SCF variation is closely related to the meteorological parameters but their temporal relationship is not stable and varies with the different regions, seasons and isotherm levels. Obviously negative temporal correlations between SCFs versus vertical velocity and relative humidity indicate that the higher vertical velocity and relative humidity the smaller SCFs. However, the patterns of temporal correlation for lower-tropospheric static stability, skin temperature and horizontal wind are relatively more complex than those of vertical velocity and humidity. For example, their close correlations are predominantly located in middle and high latitudes and vary with latitude or surface type. Although these statistical correlations have not been used to establish a certain causal relationship, our results may provide a unique point of view

  17. Transfer learning used to analyze the dynamic evolution of the dust aerosol

    NASA Astrophysics Data System (ADS)

    Ma, Yingying; Gong, Wei; Mao, Feiyue

    2015-03-01

    To keep the advantage of Support Vector Machine (SVM) in analyzing the dynamic evolution of the dust aerosol, we introduce transfer learning as a new method because transfer learning can utilize knowledge from previously collected data and add dozens of new samples, which can significantly improve dust and cloud classification results. It can also reduce the time of sample collection and make learning efficient. In this paper, we receive significant improvement effect using SVM as the basic learner in TrAdaBoost during four consecutive dust storm days, and correct one error classification in PDF. As a result, dust aerosol in high altitude can even spread to stratosphere. Moreover, in the process of dust aerosol transportation, it is highly affected by anthropogenic aerosol, for example, the color ratio (CR) changes from 0.728 to 0.460 and finally reaches 0.466, while depolarization ratio (DR) changes from 0.308 to 0.081 and finally reaches 0.156. It is indicated that the big size and non-spherical aerosol particles reduce obviously after dust aerosol deposition, but small size and spherical anthropogenic aerosol also produce a certain effect, and on March 22, 2010 had a small recovery above the ocean following the reduction of DR and CR. Due to the MODIS resolution not meeting the observation requirement and layer identification being different between CALIPSO and CloudSat, a problem such as stratocumulus cloud in low altitude still exists in aerosol and cloud classification. Lack of ground-based auxiliary data is the main problem which hinders our validation and quantitative analysis. It is pressing for a solution in future.

  18. A Wintertime Aerosol Model for the Ganga Basin, Northern India

    NASA Astrophysics Data System (ADS)

    Dey, S.; Tripathi, S. N.

    2006-05-01

    An aerosol model has been developed using mass size distributions of various chemical components measured at Kanpur (an urban location in the Ganga basin, GB, in Northern India) and applied to estimate the radiative effects of the aerosols over the entire GB during the winter season for the first time. The number size distribution of various species was derived from the measured mass concentration and the optical properties were calculated using OPAC model. The anthropogenic contribution to the total extinction was found to be more than 90%. The relative contribution of various species to the aerosol optical depth (AOD) at 0.5 μm are in the following order, (NH2)2SO4 (AS, 37%), nitrate (N, 28%), other salts (S, mainly NaCl and KCl, 19%), dust (9%) and black carbon, BC (7%). Contribution of AS, N, S to the observed AOD decreases with wavelength and that of dust increases with wavelength, whereas, BC contribution remains almost same. The extinction coefficient strongly depends on the relative humidity (RH), as the scattering by fine mode fraction (contributing 88% to the total extinction) is enhanced at high ambient RH. The spectral variation of absorption coefficient indicates that the most likely source of BC (as BC is the dominant absorbing species) in this region is fossil- fuel. The spectral variation of single scattering albedo (SSA) in the fine and coarse mode fractions and that of asymmetry parameter suggests that the internal mixing is more likely scenario, although the possibility of external mixing can not be ruled out. If the RH is lowered by ~20%, BC contribution to the AOD increases by ~3.5%, which implies that the RH is a strong controlling factor of the aerosol forcing. The mean shortwave clear sky top of the atmosphere (TOA) and surface forcing over Kanpur are -13±3 and -43±8 W m-2. Extending the TOA and surface efficiency over the entire GB, the mean TOA and surface forcing become -9±3 and -25±10 W m-2. This results in high atmospheric

  19. Establishing aerosol exposure predictive models based on vibration measurements.

    PubMed

    Soo, Jhy-Charm; Tsai, Perng-Jy; Lee, Shih-Chuan; Lu, Shih-Yi; Chang, Cheng-Ping; Liou, Yuh-When; Shih, Tung-Sheng

    2010-06-15

    This paper establishes particulate exposure predictive models based on vibration measurements under various concrete drilling conditions. The whole study was conducted in an exposure chamber using a full-scale mockup of concrete drilling simulator to simulate six drilling conditions. For each drilling condition, the vibration of the three orthogonal axes (i.e., a(x), a(y), and a(z)) was measured from the hand tool. Particulate exposure concentrations to the total suspended particulate (C(TSP)), PM(10) (C(PM10)), and PM(2.5) (C(PM2.5)) were measured at the downwind side of the drilling simulator. Empirical models for predicting C(TSP), C(PM10) and C(PM2.5) were done based on measured a(x), a(y), and a(z) using the generalized additive model. Good agreement between measured aerosol exposures and vibrations was found with R(2)>0.969. Our results also suggest that a(x) was mainly contributed by the abrasive wear. On the other hand, a(y) and a(z) were mainly contributed by both the impact wear and brittle fracture wear. The approach developed from the present study has the potential to provide a cheaper and convenient method for assessing aerosol exposures from various emission sources, particularly when conducting conventional personal aerosol samplings are not possible in the filed.

  20. Evaluation of a size-resolved aerosol model based on satellite and ground observations and its implication on aerosol forcing

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoyan; Yu, Fangqun

    2016-04-01

    The latest AeroCom phase II experiments have showed a large diversity in the simulations of aerosol concentrations, size distribution, vertical profile, and optical properties among 16 detailed global aerosol microphysics models, which contribute to the large uncertainty in the predicted aerosol radiative forcing and possibly induce the distinct climate change in the future. In the last few years, we have developed and improved a global size-resolved aerosol model (Yu and Luo, 2009; Ma et al., 2012; Yu et al., 2012), GEOS-Chem-APM, which is a prognostic multi-type, multi-component, size-resolved aerosol microphysics model, including state-of-the-art nucleation schemes and condensation of low volatile secondary organic compounds from successive oxidation aging. The model is one of 16 global models for AeroCom phase II and participated in a couple of model inter-comparison experiments. In this study, we employed multi-year aerosol optical depth (AOD) data from 2004 to 2012 taken from ground-based Aerosol Robotic Network (AERONET) measurements and Moderate Resolution Imaging Spectroradiometer (MODIS), Multiangle Imaging SpectroRadiometer (MISR) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite retrievals to evaluate the performance of the GEOS-Chem-APM in predicting aerosol optical depth, including spatial distribution, reginal variation and seasonal variabilities. Compared to the observations, the modelled AOD is overall good over land, but quite low over ocean possibly due to low sea salt emission in the model and/or higher AOD in satellite retrievals, specifically MODIS and MISR. We chose 72 AERONET sites having at least 36 months data available and representative of high spatial domain to compare with the model and satellite data. Comparisons in various representative regions show that the model overall agrees well in the major anthropogenic emission regions, such as Europe, East Asia and North America. Relative to the observations, the modelled AOD is

  1. Modelling Volcanic Aerosol-Cloud Interactions in Warm Cumulus Cloud Using the High Resolution Nested Suite of the UK Met Office Unified Model

    NASA Astrophysics Data System (ADS)

    Hodgson, A. K.; Field, P.; Carslaw, K. S.; Hill, A. A.; Shipway, B. J.; Grosvenor, D. P.; Marsham, J. H.

    2014-12-01

    The impacts that aerosols have on clouds and clouds have on aerosols remain the largest uncertainty in terms of the effect on radiative forcing. Regional and global models are unable to resolve these small scale interactions, while high resolution eddy-resolving models are unable to capture the larger scale dynamics of the atmosphere and can only be run over a limited size domain for a limited time. Here we present results using the high resolution (1km, 0.3km) nested version of the UK Met Office Unified Model (UM) which bridges the scale gap between models. A new microphysics scheme, Cloud and AeroSol Interactive Microphysics (CASIM) is coupled to a chemistry and aerosol scheme (GLOMAP-mode) which allows for fully interactive aerosol and cloud microphysics.Results showing the effect of volcanic aerosol from the slowly degassing Kilauea volcano, Hawaii on trade wind cumuli will be presented. The presence of a subtropical high pressure in the summer allows the study of aerosol-cloud interactions in a uniform unpolluted marine background environment without the complications of anthropogenic pollution. Satellite data has shown that cumulus clouds affected by the volcanic plume had smaller cloud droplets, reduced precipitation efficiency, increased cloud amount and higher cloud tops. Other researchers have hypothesised that that the observed changes in cloud properties cannot be explained by the orographic effect of the island or the sea surface temperature anomaly. We present results using CASIM in the UM at high resolution to systematically compare the relative effects of dynamical and aerosol-cloud interactions. Initial results show that the orography of the island does not have a significant impact on the cumulus cloud further downwind from the island but there is an effect in the immediate vicinity of the island. Initial results also indicate that 1km resolution is not high enough to resolve small cumulus cloud.

  2. The MESSy aerosol submodel MADE3 (v2.0b): description and a box model test

    NASA Astrophysics Data System (ADS)

    Kaiser, J. C.; Hendricks, J.; Righi, M.; Riemer, N.; Zaveri, R. A.; Metzger, S.; Aquila, V.

    2014-06-01

    We introduce MADE3 (Modal Aerosol Dynamics model for Europe, adapted for global applications, 3rd generation; version: MADE3v2.0b), an aerosol dynamics submodel for application within the MESSy framework (Modular Earth Submodel System). MADE3 builds on the predecessor aerosol submodels MADE and MADE-in. Its main new features are the explicit representation of coarse mode particle interactions both with other particles and with condensable gases, and the inclusion of hydrochloric acid (HCl) / chloride (Cl) partitioning between the gas and condensed phases. The aerosol size distribution is represented in the new submodel as a superposition of nine lognormal modes: one for fully soluble particles, one for insoluble particles, and one for mixed particles in each of three size ranges (Aitken, accumulation, and coarse mode size ranges). In order to assess the performance of MADE3 we compare it to its predecessor MADE and to the much more detailed particle-resolved aerosol model PartMC-MOSAIC in a box model simulation of an idealised marine boundary layer test case. MADE3 and MADE results are very similar, except in the coarse mode, where the aerosol is dominated by sea spray particles. Cl is reduced in MADE3 with respect to MADE due to the HCl / Cl partitioning that leads to Cl removal from the sea spray aerosol in our test case. Additionally, the aerosol nitrate concentration is higher in MADE3 due to the condensation of nitric acid on coarse mode particles. MADE3 and PartMC-MOSAIC show substantial differences in the fine particle size distributions (sizes ≲ 2 μm) that could be relevant when simulating climate effects on a global scale. Nevertheless, the agreement between MADE3 and PartMC-MOSAIC is very good when it comes to coarse particle size distributions (sizes ≳ 2 μm), and also in terms of aerosol composition. Considering these results and the well-established ability of MADE in reproducing observed aerosol loadings and composition, MADE3 seems suitable for

  3. The MESSy aerosol submodel MADE3 (v2.0b): description and a box model test

    SciTech Connect

    Kaiser, J. C.; Hendricks, J.; Righi, M.; Riemer, N.; Zaveri, R. A.; Metzger, S.; Aquila, V.

    2014-01-01

    We introduce MADE3 (Modal Aerosol Dynamics model for Europe, adapted for global applications, 3rd generation; version: MADE3v2.0b), an aerosol dynamics submodel for application within the MESSy framework (Modular Earth Submodel System). MADE3 builds on the predecessor aerosol submodels MADE and MADE-in. Its main new features are the explicit representation of coarse mode particle interactions both with other particles and with condensable gases, and the inclusion of hydrochloric acid (HCl) / chloride (Cl) partitioning between the gas and condensed phases. The aerosol size distribution is represented in the new submodel as a superposition of nine lognormal modes: one for fully soluble particles, one for insoluble particles, and one for mixed particles in each of three size ranges (Aitken, accumulation, and coarse mode size ranges). In order to assess the performance of MADE3 we compare it to its predecessor MADE and to the much more detailed particle-resolved aerosol model PartMC-MOSAIC in a box model simulation of an idealised marine boundary layer test case. MADE3 and MADE results are very similar, except in the coarse mode, where the aerosol is dominated by sea spray particles. Cl is reduced in MADE3 with respect to MADE due to the HCl / Cl partitioning that leads to Cl removal from the sea spray aerosol in our test case. Additionally, the aerosol nitrate concentration is higher in MADE3 due to the condensation of nitric acid on coarse mode particles. MADE3 and PartMC-MOSAIC show substantial differences in the fine particle size distributions (sizes ≲ 2 μm) that could be relevant when simulating climate effects on a global scale. Nevertheless, the agreement between MADE3 and PartMC-MOSAIC is very good when it comes to coarse particle size distributions (sizes ≳ 2 μm), and also in terms of aerosol composition. Finally, considering these results and the well-established ability of MADE in reproducing observed aerosol loadings and composition, MADE3 seems

  4. Satellite observations and EMAC model calculations of sulfate aerosols from Kilauea: a study of aerosol formation, processing, and loss

    NASA Astrophysics Data System (ADS)

    Penning de Vries, Marloes; Beirle, Steffen; Brühl, Christoph; Dörner, Steffen; Pozzer, Andrea; Wagner, Thomas

    2016-04-01

    The currently most active volcano on Earth is Mount Kilauea on Hawaii, as it has been in a state of continuous eruption since 1983. The opening of a new vent in March 2008 caused half a year of strongly increased SO2 emissions, which in turn led to the formation of a sulfate plume with an extent of at least two thousand kilometers. The plume could be clearly identified from satellite measurements from March to November, 2008. The steady trade winds in the region and the lack of interfering sources allowed us to determine the life time of SO2 from Kilauea using only satellite-based measurements (no a priori or model information). The current investigation focuses on sulfate aerosols: their formation, processing and subsequent loss. Using space-based aerosol measurements by MODIS, we study the evolution of aerosol optical depth, which first increases as a function of distance from the volcano due to aerosol formation from SO2 oxidation, and subsequently decreases as aerosols are deposited to the surface. The outcome is compared to results from calculations using the EMAC (ECHAM/MESSy Atmospheric Chemistry) model to test the state of understanding of the sulfate aerosol life cycle. For this comparison, a particular focus is on the role of clouds and wet removal processes.

  5. Online Simulations and Forecasts of the Global Aerosol Distribution in the NASA GEOS-5 Model

    NASA Technical Reports Server (NTRS)

    Colarco, Peter

    2006-01-01

    We present an analysis of simulations of the global aerosol system in the NASA GEOS-5 transport, radiation, and chemistry model. The model includes representations of all major tropospheric aerosol species, including dust, sea salt, black carbon, particulate organic matter, and sulfates. The aerosols are run online for the period 2000 through 2005 in a simulation driven by assimilated meteorology from the NASA Goddard Data Assimilation System. Aerosol surface mass concentrations are compared with existing long-term surface measurement networks. Aerosol optical thickness is compared with ground-based AERONET sun photometry and space-based retrievals from MODIS, MISR, and OMI. Particular emphasis is placed here on consistent sampling of model and satellite aerosol optical thickness to account for diurnal variations in aerosol optical properties. Additionally, we illustrate the use of this system for providing chemical weather forecasts in support of various NASA and community field missions.

  6. Modeling aerosol-cloud interactions with a self-consistent cloud scheme in a general circulation model

    SciTech Connect

    Ming, Y; Ramaswamy, V; Donner, L J; Phillips, V T; Klein, S A; Ginoux, P A; Horowitz, L H

    2005-05-02

    This paper describes a self-consistent prognostic cloud scheme that is able to predict cloud liquid water, amount and droplet number (N{sub d}) from the same updraft velocity field, and is suitable for modeling aerosol-cloud interactions in general circulation models (GCMs). In the scheme, the evolution of droplets fully interacts with the model meteorology. An explicit treatment of cloud condensation nuclei (CCN) activation allows the scheme to take into account the contributions to N{sub d} of multiple types of aerosol (i.e., sulfate, organic and sea-salt aerosols) and kinetic limitations of the activation process. An implementation of the prognostic scheme in the Geophysical Fluid Dynamics Laboratory (GFDL) AM2 GCM yields a vertical distribution of N{sub d} characteristic of maxima in the lower troposphere differing from that obtained through diagnosing N{sub d} empirically from sulfate mass concentrations. As a result, the agreement of model-predicted present-day cloud parameters with satellite measurements is improved compared to using diagnosed N{sub d}. The simulations with pre-industrial and present-day aerosols show that the combined first and second indirect effects of anthropogenic sulfate and organic aerosols give rise to a global annual mean flux change of -1.8 W m{sup -2} consisting of -2.0 W m{sup -2} in shortwave and 0.2 W m{sup -2} in longwave, as model response alters cloud field, and subsequently longwave radiation. Liquid water path (LWP) and total cloud amount increase by 19% and 0.6%, respectively. Largely owing to high sulfate concentrations from fossil fuel burning, the Northern Hemisphere mid-latitude land and oceans experience strong cooling. So does the tropical land which is dominated by biomass burning organic aerosol. The Northern/Southern Hemisphere and land/ocean ratios are 3.1 and 1.4, respectively. The calculated annual zonal mean flux changes are determined to be statistically significant, exceeding the model's natural variations

  7. Modeling regional secondary organic aerosol using the Master Chemical Mechanism

    NASA Astrophysics Data System (ADS)

    Li, Jingyi; Cleveland, Meredith; Ziemba, Luke D.; Griffin, Robert J.; Barsanti, Kelley C.; Pankow, James F.; Ying, Qi

    2015-02-01

    A modified near-explicit Master Chemical Mechanism (MCM, version 3.2) with 5727 species and 16,930 reactions and an equilibrium partitioning module was incorporated into the Community Air Quality Model (CMAQ) to predict the regional concentrations of secondary organic aerosol (SOA) from volatile organic compounds (VOCs) in the eastern United States (US). In addition to the semi-volatile SOA from equilibrium partitioning, reactive surface uptake processes were used to simulate SOA formation due to isoprene epoxydiol, glyoxal and methylglyoxal. The CMAQ-MCM-SOA model was applied to simulate SOA formation during a two-week episode from August 28 to September 7, 2006. The southeastern US has the highest SOA, with a maximum episode-averaged concentration of ∼12 μg m-3. Primary organic aerosol (POA) and SOA concentrations predicted by CMAQ-MCM-SOA agree well with AMS-derived hydrocarbon-like organic aerosol (HOA) and oxygenated organic aerosol (OOA) urban concentrations at the Moody Tower at the University of Houston. Predicted molecular properties of SOA (O/C, H/C, N/C and OM/OC ratios) at the site are similar to those reported in other urban areas, and O/C values agree with measured O/C at the same site. Isoprene epoxydiol is predicted to be the largest contributor to total SOA concentration in the southeast US, followed by methylglyoxal and glyoxal. The semi-volatile SOA components are dominated by products from β-caryophyllene oxidation, but the major species and their concentrations are sensitive to errors in saturation vapor pressure estimation. A uniform decrease of saturation vapor pressure by a factor of 100 for all condensable compounds can lead to a 150% increase in total SOA. A sensitivity simulation with UNIFAC-calculated activity coefficients (ignoring phase separation and water molecule partitioning into the organic phase) led to a 10% change in the predicted semi-volatile SOA concentrations.

  8. A simplified model of aerosol removal by containment sprays

    SciTech Connect

    Powers, D.A. ); Burson, S.B. . Div. of Safety Issue Resolution)

    1993-06-01

    Spray systems in nuclear reactor containments are described. The scrubbing of aerosols from containment atmospheres by spray droplets is discussed. Uncertainties are identified in the prediction of spray performance when the sprays are used as a means for decontaminating containment atmospheres. A mechanistic model based on current knowledge of the physical phenomena involved in spray performance is developed. With this model, a quantitative uncertainty analysis of spray performance is conducted using a Monte Carlo method to sample 20 uncertain quantities related to phenomena of spray droplet behavior as well as the initial and boundary conditions expected to be associated with severe reactor accidents. Results of the uncertainty analysis are used to construct simplified expressions for spray decontamination coefficients. Two variables that affect aerosol capture by water droplets are not treated as uncertain; they are (1) [open quote]Q[close quote], spray water flux into the containment, and (2) [open quote]H[close quote], the total fall distance of spray droplets. The choice of values of these variables is left to the user since they are plant and accident specific. Also, they can usually be ascertained with some degree of certainty. The spray decontamination coefficients are found to be sufficiently dependent on the extent of decontamination that the fraction of the initial aerosol remaining in the atmosphere, m[sub f], is explicitly treated in the simplified expressions. The simplified expressions for the spray decontamination coefficient are given. Parametric values for these expressions are found for median, 10 percentile, and 90 percentile values in the uncertainty distribution for the spray decontamination coefficient. Examples are given to illustrate the utility of the simplified expressions to predict spray decontamination of an aerosol-laden atmosphere.

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

    DTIC Science & Technology

    2005-12-01

    tropopause. These include a background stratospheric aerosol model, volcanic aerosol models and an upper atmosphere aerosol model. These models will not...scaling factor is a function of VIS, the season and the volcanic conditions. The normalised attenuation coefficients are defined as ratios of the...different values of VIS: 2, 5, 10, 23 and 50 km. The upper altitude profiles are computed as a function of the season and volcanic conditions and stored

  10. High-resolution modeling of the influences of absorbing aerosols on rainfall over northern India and the Himalaya foothills during boreal summer

    NASA Astrophysics Data System (ADS)

    Kim, K.; Lau, W. K.; Tao, W.; Shi, J. J.; Tan, Q.; Chin, M.; Matsui, T.; Kemp, E. M.; Peters-Lidard, C. D.

    2012-12-01

    High elevation and steep topography of Tibetan Plateau and the Himalayas foothills regions are important components of the South Asian summer monsoon system. Strong orographic forcing combined with abundant moisture from the Arabian Sea and the Bay of Bengal and aerosols stacked up against the southern slope of the Tibetan Plateau produce complex physical and dynamical effects on monsoon rainfall and circulation. In this work, we use the NASA Unified Weather Research and Forecasting (Nu-WRF) model to study the effect of aerosol radiative forcing on the short-term predictability (1-7 days) of the South Asian monsoon rainfall system. Two sets of 7-day forecasting experiments were conducted with and without aerosol radiative forcing. Each set consists of 34 7-day forcasts with initial conditions from daily reanalysis and GEOS-5 aerosol distribution (only for aerosol run) from June 11- July 14, 2008. Nu-WRF, without aerosol forcing captures the horizontal distribution of 7-day mean precipitation reasonably well, but it tends to over-estimates rainfall over the central India. The biases are especially larger in the upwind side of the western Ghats and northeast India and Bangladesh. Preliminary results show that inclusion of aerosol radiative forcing and interaction with dynamics reduces rainfall over the Indo-Gangetic plain where aerosol loadinng is high, but enhances rainfall downstream of the prevailing monsoon flow in the southern slope of Tibetan Plateau, especially over the northeast India and foothills regions, consistent with the EHP hypothesis. Effect of aerosol radiative forcing is small during the first two days of forecasts. Rainfall anomalies generated by atmospheric feedback induced by aerosol radiative forcing becomes statistically significant and large enough to be separable from growing model biases after three days of simulation. The results indicate the inclusion of aerosol radiative forcing may improve short-term (4-7 day) forecasting skill in

  11. Modelling of primary aerosols in the chemical transport model MOCAGE: development and evaluation of aerosol physical parameterizations

    NASA Astrophysics Data System (ADS)

    Sič, B.; El Amraoui, L.; Marécal, V.; Josse, B.; Arteta, J.; Guth, J.; Joly, M.; Hamer, P. D.

    2015-02-01

    This paper deals with recent improvements to the global chemical transport model of Météo-France MOCAGE (Modèle de Chimie Atmosphérique à Grande Echelle) that consists of updates to different aerosol parameterizations. MOCAGE only contains primary aerosol species: desert dust, sea salt, black carbon, organic carbon, and also volcanic ash in the case of large volcanic eruptions. We introduced important changes to the aerosol parameterization concerning emissions, wet deposition and sedimentation. For the emissions, size distribution and wind calculations are modified for desert dust aerosols, and a surface sea temperature dependant source function is introduced for sea salt aerosols. Wet deposition is modified toward a more physically realistic representation by introducing re-evaporation of falling rain and snowfall scavenging and by changing the in-cloud scavenging scheme along with calculations of precipitation cloud cover and rain properties. The sedimentation scheme update includes changes regarding the stability and viscosity calculations. Independent data from satellites (MODIS, SEVIRI), the ground (AERONET, EMEP), and a model inter-comparison project (AeroCom) are compared with MOCAGE simulations and show that the introduced changes brought a significant improvement on aerosol representation, properties and global distribution. Emitted quantities of desert dust and sea salt, as well their lifetimes, moved closer towards values of AeroCom estimates and the multi-model average. When comparing the model simulations with MODIS aerosol optical depth (AOD) observations over the oceans, the updated model configuration shows a decrease in the modified normalized mean bias (MNMB; from 0.42 to 0.10) and a better correlation (from 0.06 to 0.32) in terms of the geographical distribution and the temporal variability. The updates corrected a strong positive MNMB in the sea salt representation at high latitudes (from 0.65 to 0.16), and a negative MNMB in the desert

  12. MATCH-SALSA - Multi-scale Atmospheric Transport and CHemistry model coupled to the SALSA aerosol microphysics model - Part 1: Model description and evaluation

    NASA Astrophysics Data System (ADS)

    Andersson, C.; Bergström, R.; Bennet, C.; Robertson, L.; Thomas, M.; Korhonen, H.; Lehtinen, K. E. J.; Kokkola, H.

    2014-05-01

    We have implemented the sectional aerosol dynamics model SALSA in the European scale chemistry-transport model MATCH (Multi-scale Atmospheric Transport and Chemistry). The new model is called MATCH-SALSA. It includes aerosol microphysics, with several formulations for nucleation, wet scavenging and condensation. The model reproduces observed higher particle number concentration (PNC) in central Europe and lower concentrations in remote regions. The model PNC size distribution peak occurs at the same or smaller particle size as the observed peak at five measurement sites spread across Europe. Total PNC is underestimated at Northern and Central European sites and accumulation mode PNC is underestimated at all investigated sites. On the other hand the model performs well for particle mass, including secondary inorganic aerosol components. Elemental and organic carbon concentrations are underestimated at many of the sites. Further development is needed, primarily for treatment of secondary organic aerosol, both in terms of biogenic emissions and chemical transformation, and for nitrogen gas-particle partitioning. Updating the biogenic SOA scheme will likely have a large impact on modeled PM2.5 and also affect the model performance for PNC through impacts on nucleation and condensation. An improved nitrogen partitioning model may also improve the description of condensational growth.

  13. Remote sensing of aerosol plumes: a semianalytical model.

    PubMed

    Alakian, Alexandre; Marion, Rodolphe; Briottet, Xavier

    2008-04-10

    A semianalytical model, named APOM (aerosol plume optical model) and predicting the radiative effects of aerosol plumes in the spectral range [0.4,2.5 microm], is presented in the case of nadir viewing. It is devoted to the analysis of plumes arising from single strong emission events (high optical depths) such as fires or industrial discharges. The scene is represented by a standard atmosphere (molecules and natural aerosols) on which a plume layer is added at the bottom. The estimated at-sensor reflectance depends on the atmosphere without plume, the solar zenith angle, the plume optical properties (optical depth, single-scattering albedo, and asymmetry parameter), the ground reflectance, and the wavelength. Its mathematical expression as well as its numerical coefficients are derived from MODTRAN4 radiative transfer simulations. The DISORT option is used with 16 fluxes to provide a sufficiently accurate calculation of multiple scattering effects that are important for dense smokes. Model accuracy is assessed by using a set of simulations performed in the case of biomass burning and industrial plumes. APOM proves to be accurate and robust for solar zenith angles between 0 degrees and 60 degrees whatever the sensor altitude, the standard atmosphere, for plume phase functions defined from urban and rural models, and for plume locations that extend from the ground to a height below 3 km. The modeling errors in the at-sensor reflectance are on average below 0.002. They can reach values of 0.01 but correspond to low relative errors then (below 3% on average). This model can be used for forward modeling (quick simulations of multi/hyperspectral images and help in sensor design) as well as for the retrieval of the plume optical properties from remotely sensed images.

  14. Using the Convective Cloud Field Model (CCFM) to investigate aerosol-convection interactions in ECHAM6-HAM

    NASA Astrophysics Data System (ADS)

    Kipling, Zak; Stier, Philip; Wagner, Till

    2014-05-01

    Convection plays an important role in the climate system through its effects on radiation, precipitation, large-scale dynamics and vertical transport of aerosols and trace gases. The effects of aerosols on the development of convective cloud and precipitation are a source of considerable uncertainty in current climate modelling. Most current global climate models use 'mass-flux' convection schemes, which represent the ensemble of convective clouds in a GCM column by a single 'mean' updraught. In addition to over-simplifying the representation of such clouds, this presents particular problems in the context of aerosol-convection interactions: firstly because the relationship between aerosol and the droplet size distribution depends on the vertical velocity distribution, about which little or no information is available, and secondly because the effects of convective transport and scavenging may vary nonlinearly over the ensemble (e.g. between precipitating and non-precipitating clouds and due to different loadings). The Convective Cloud Field Model (CCFM) addresses these limitations by simulating a spectrum of updraughts with different cross-sectional areas within each GCM column, based on the quasi-equilibrium approach of Arakawa and Schubert. For each cloud type, an entraining Lagrangian parcel model is initiated by perturbations at the surface, allowing a realistic vertical velocity to develop by cloud base so that detailed size-resolved microphysics can be represented within the cloud above. These different cloud types interact via competition for resolved-scale convective available potential energy (CAPE). Transport of water, aerosol and other tracers is calculated separately for each cloud type, allowing for different entrainment and scavenging behaviours. By using CCFM embedded within the ECHAM6-HAM aerosol-climate model, we show how this approach can both improve the distribution of convective precipitation events compared to a typical mass-flux scheme, and

  15. Modeling aerosols and their interactions with shallow cumuli during the 2007 CHAPS field study

    SciTech Connect

    Shrivastava, ManishKumar B.; Berg, Larry K.; Fast, Jerome D.; Easter, Richard C.; Laskin, Alexander; Chapman, Elaine G.; Gustafson, William I.; Liu, Ying; Berkowitz, Carl M.

    2013-02-07

    The Weather Research and Forecasting model coupled with chemistry (WRF-Chem) is used to simulate relationships between aerosols and clouds in the vicinity of Oklahoma City during the June 2007 Cumulus Humilis Aerosol Processing Study (CHAPS). The regional scale simulation completed using 2 km horizontal grid spacing evaluates four important relationships between aerosols and shallow cumulus clouds observed during CHAPS. First, the model reproduces the trends of higher nitrate volume fractions in cloud droplet residuals compared to interstitial non-activated aerosols, as measured using the Aerosol Mass Spectrometer. Comparing simulations with cloud chemistry turned on and off, we show that nitric acid vapor uptake by cloud droplets explains the higher nitrate content of cloud droplet residuals. Second, as documented using an offline code, both aerosol water and other inorganics (OIN), which are related to dust and crustal emissions, significantly affect predicted aerosol optical properties. Reducing the OIN content of wet aerosols by 50% significantly improves agreement of model predictions with measurements of aerosol optical properties. Third, the simulated hygroscopicity of aerosols is too high as compared to their hygroscopicity derived from cloud condensation nuclei and particle size distribution measurements, indicating uncertainties associated with simulating size-dependent chemical composition and treatment of aerosol mixing state within the model. Fourth, the model reasonably represents the observations of the first aerosol indirect effect where pollutants in the vicinity of Oklahoma City increase cloud droplet number concentrations and decrease the droplet effective radius. While previous studies have often focused on cloud-aerosol interactions in stratiform and deep convective clouds, this study highlights the ability of regional-scale models to represent some of the important aspects of cloud-aerosol interactions associated with fields of short

  16. Representation of Nucleation Mode Microphysics in a Global Aerosol Model with Sectional Microphysics

    NASA Technical Reports Server (NTRS)

    Lee, Y. H.; Pierce, J. R.; Adams, P. J.

    2013-01-01

    In models, nucleation mode (1 nmaerosol microphysical processes or can be parameterized to obtain the growth and survival of nuclei to the model's lower size boundary. This study investigates how the representation of nucleation mode microphysics impacts aerosol number predictions in the TwO-Moment Aerosol Sectional (TOMAS) aerosol microphysics model running with the GISS GCM II-prime by varying its lowest diameter boundary: 1 nm, 3 nm, and 10 nm. The model with the 1 nm boundary simulates the nucleation mode particles with fully resolved microphysical processes, while the model with the 10 nm and 3 nm boundaries uses a nucleation mode dynamics parameterization to account for the growth of nucleated particles to 10 nm and 3 nm, respectively.We also investigate the impact of the time step for aerosol microphysical processes (a 10 min versus a 1 h time step) to aerosol number predictions in the TOMAS models with explicit dynamics for the nucleation mode particles (i.e., 3 nm and 1 nm boundary). The model with the explicit microphysics (i.e., 1 nm boundary) with the 10 min time step is used as a numerical benchmark simulation to estimate biases caused by varying the lower size cutoff and the time step. Different representations of the nucleation mode have a significant effect on the formation rate of particles larger than 10 nm from nucleated particles (J10) and the burdens and lifetimes of ultrafinemode (10 nm=Dp =70 nm) particles but have less impact on the burdens and lifetimes of CCN-sized particles. The models using parameterized microphysics (i.e., 10 nm and 3 nm boundaries) result in higher J10 and shorter coagulation lifetimes of ultrafine-mode particles than the model with explicit dynamics (i.e., 1 nm boundary). The spatial distributions of CN10 (Dp =10 nm) and CCN(0.2 %) (i.e., CCN concentrations at 0.2%supersaturation) are moderately affected, especially CN10 predictions above 700 h

  17. Improving aerosol interaction with clouds and precipitation in a regional chemical weather modeling system

    NASA Astrophysics Data System (ADS)

    Zhou, C.; Zhang, X.; Gong, S.; Wang, Y.; Xue, M.

    2016-01-01

    A comprehensive aerosol-cloud-precipitation interaction (ACI) scheme has been developed under a China Meteorological Administration (CMA) chemical weather modeling system, GRAPES/CUACE (Global/Regional Assimilation and PrEdiction System, CMA Unified Atmospheric Chemistry Environment). Calculated by a sectional aerosol activation scheme based on the information of size and mass from CUACE and the thermal-dynamic and humid states from the weather model GRAPES at each time step, the cloud condensation nuclei (CCN) are interactively fed online into a two-moment cloud scheme (WRF Double-Moment 6-class scheme - WDM6) and a convective parameterization to drive cloud physics and precipitation formation processes. The modeling system has been applied to study the ACI for January 2013 when several persistent haze-fog events and eight precipitation events occurred.

    The results show that aerosols that interact with the WDM6 in GRAPES/CUACE obviously increase the total cloud water, liquid water content, and cloud droplet number concentrations, while decreasing the mean diameters of cloud droplets with varying magnitudes of the changes in each case and region. These interactive microphysical properties of clouds improve the calculation of their collection growth rates in some regions and hence the precipitation rate and distributions in the model, showing 24 to 48 % enhancements of threat score for 6 h precipitation in almost all regions. The aerosols that interact with the WDM6 also reduce the regional mean bias of temperature by 3 °C during certain precipitation events, but the monthly means bias is only reduced by about 0.3 °C.

  18. SOIR/VEX mesospheric aerosols observations and modelling

    NASA Astrophysics Data System (ADS)

    Wilquet, Valérie; Carine Vandaele, Ann; Drummond, Rachel; Mahieux, Arnaud; Robert, Séverine; Daerden, Frank; Neary, Lori; Bertaux, Jean-Loup

    2013-04-01

    SPICAV/SOIR on-board Venus Express is able to target the layer of aerosols above the cloud layer at the terminator (Wilquet et al., 2009). A high temporal variability in the aerosol content in Venus' atmosphere was inferred from SOIR observations, as well as a latitudinal dependency of the aerosol loading (Wilquet et al., 2012). This is in agreement with results from previous missions and with the facts that (i) H2SO4 aerosol particles are formed through SO2 photo-oxidation and hydration at the cloud top of Venus, (ii) SO2 photolysis is more efficient at low latitudes, (iii) the altitude of the cloud top is up to one scale height lower in the polar region than at the equator. A increasing SO2 abundance with increasing altitude was recently observed with SPICAV-UV at altitudes of ~ 85-105 km (Belyaev et al., 2012) but also from microwave ground-based spectra in the Venus mesosphere (Sandor et al., 2010), which suggest a source of SO2 at high altitudes. Zhang et al. (2012) proposed a one dimensional photochemistry-diffusion model in order to reconcile these puzzling findings; he suggested that H2SO4 might be a source of SO2 above 90 km through aerosol evaporation followed by SO3 photolysis. This model and the observations are however disputed by others demonstrating the necessity for a more global interpretation of the observations and for modelling of the upper haze layer. For example, the variations in aerosol loading can be compared to other key parameters of the atmosphere retrieved from the same SOIR spectra such as water and SO2 composition or temperature. In addition, a microphysical model is being developed that will calculate the time dependent haze particle size distributions assuming an initial size distribution of background sulphate aerosols. The model will simulate the formation, growth, evaporation, and sedimentation of particles. Results of this on-going research will be presented and discussed. References : Belyaev, D.A., F. Montmessin, J.-L. Bertaux

  19. Aerosol microphysics modules in the framework of the ECHAM5 climate model - intercomparison under stratospheric conditions

    NASA Astrophysics Data System (ADS)

    Kokkola, H.; Hommel, R.; Kazil, J.; Niemeier, U.; Partanen, A.-I.; Feichter, J.; Timmreck, C.

    2009-07-01

    In this manuscript, we present an intercomparison of three different aerosol microphysics modules that are implemented in the climate model ECHAM5. The comparison was done between the modal aerosol microphysics module M7, which is currently the default aerosol microphysical core in ECHAM5, and two sectional aerosol microphysics modules SALSA, and SAM2. The detailed aerosol microphysical model MAIA was used as a reference to evaluate the results of the aerosol microphysics modules with respect to sulphate aerosol. The ability of the modules to describe the development of the aerosol size distribution was tested in a zero dimensional framework. We evaluated the strengths and weaknesses of different approaches under different types of stratospheric conditions. Also, we present an improved method for the time integration in M7 and study how the setup of the modal aerosol modules affects the evolution of the aerosol size distribution. Intercomparison simulations were carried out with varying SO2 concentrations from background conditions to extreme values arising from stratospheric injections by large volcanic eruptions. Under background conditions, all microphysics modules were in good agreement describing the shape of the aerosol size distribution, but the scatter between the model results increased with increasing SO2 concentrations. In particular in the volcanic case the setups of the aerosol modules have to be adapted in order to dependably capture the evolution of the aerosol size distribution, and to perform in global model simulations. In summary, this intercomparison serves as a review of the different aerosol microphysics modules which are currently available for the climate model ECHAM5.

  20. Modeling Electrical Structure of the Artificial Charged Aerosol Cloud

    NASA Astrophysics Data System (ADS)

    Davydenko, S.; Iudin, D.; Klimashov, V.; Kostinskiy, A. J.; Syssoev, V.

    2014-12-01

    The electric structure of the unipolar charged aerosol cloud is considered. The cloud of the volume about 30 cubic meters is generated in the open atmosphere by the original aeroelectrical facility consisting of the source of the aquated ions and the high-voltage discharger. Representing the charge density distribution as a superposition of regular and irregular parts, a model of the electrical structure of the cloud is developed. The regular part is calculated under the stationary current approximation taking into account the source current structure, the shape of the cloud, and results of the multi-point measurements of the electric field and conductivity in the vicinity of the cloud. The irregular part describes random spatiotemporal fluctuations of the charge density which are assumed to be proportional to the aerosol number density. It is shown that a quasi-electrostatic field of the charged aerosol is characterized by significant spatial fluctuations showing the scale invariance. The mean-square fluctuations of the voltage between different parts of the cloud are proportional to the square root of its linear dimensions and may reach significant values even in the absence of the regular field. The basic parameters of the fluctuating spatial structure of the electric field inside the charged aerosol cloud are estimated. It is shown that the charge density fluctuations could lead to a significant (up to 2,5 times) local enhancement of the electric field as compared to the field of the regular part of the charge density. The above effect could serve as one of the important mechanisms of the spark initiation.

  1. Development and application of an aerosol screening model for size-resolved urban aerosols.

    PubMed

    Stanier, Charles O; Lee, Sang-Rin

    2014-06-01

    Predictive models of vehicular ultrafine particles less than 0.1 microm in diameter (UFPs*) and other urban pollutants with high spatial and temporal variation are useful and important in applications such as (1) decision support for infrastructure projects, emissions controls, and transportation-mode shifts; (2) the interpretation and enhancement of observations (e.g., source apportionment, extrapolation, interpolation, and gap-filling in space and time); and (3) the generation of spatially and temporally resolved exposure estimates where monitoring is unfeasible. The objective of the current study was to develop, test, and apply the Aerosol Screening Model (ASM), a new physically based vehicular UFP model for use in near-road environments. The ASM simulates hourly average outdoor concentrations of roadway-derived aerosols and gases. Its distinguishing features include user-specified spatial resolution; use of the Weather Research and Forecasting (WRF) meteorologic model for winds estimates; use of a database of more than 100,000 road segments in the Los Angeles, California, region, including freeway ramps and local streets; and extensive testing against more than 9000 hours of observed particle concentrations at 11 sites. After initialization of air parcels at an upwind boundary, the model solves for vehicle emissions, dispersion, coagulation, and deposition using a Lagrangian modeling framework. The Lagrangian parcel of air is subdivided vertically (into 11 levels) and in the crosswind direction (into 3 parcels). It has overall dimensions of 10 m (downwind), 300 m (vertically), and 2.1 km (crosswind). The simulation is typically started 4 km upwind from the receptor, that is, the location at which the exposure is to be estimated. As parcels approach the receptor, depending on the user-specified resolution, step size is decreased, and crosswind resolution is enhanced through subdivision of parcels in the crosswind direction. Hourly concentrations and size

  2. Aerosol microphysics modules in the framework of the ECHAM5 climate model - intercomparison under stratospheric conditions

    NASA Astrophysics Data System (ADS)

    Kokkola, H.; Hommel, R.; Kazil, J.; Niemeier, U.; Partanen, A.-I.; Feichter, J.; Timmreck, C.

    2009-03-01

    In this manuscript, we present an intercomparison of three different aerosol microphysics modules that are implemented in the climate model ECHAM5. The comparison was done between the modal aerosol microphysics module M7, which is currently the default aerosol microphysical core in ECHAM5, and two sectional aerosol microphysics modules SALSA, and SAM2. A detailed aerosol microphycical model MAIA was used as a reference model to evaluate the results of the aerosol microphysics modules with respect to sulphate aerosol. The ability of the modules to describe the development of the aerosol size distribution was tested in a zero dimensional framework. We evaluated the strengths and weaknesses of different approaches under different types of stratospheric conditions. Also, we present an improved method for the time integration in M7 and study how the setup of the modal approach affects the evolution of the aerosol size distribution. Intercomparison simulations were carried out with varying SO2 concentrations from background conditions to extreme values arising from stratospheric injections of large volcanic eruptions. Under background conditions, all microphysics modules were in good agreement describing the shape of the size distribution but the scatter between the model results increased with increasing SO2 concentrations. In particular for the volcanic case the module setups have to be redefined to be applied in global model simulations capturing respective sulphate particle formation events. Summarized, this intercomparison serves as a review on the different aerosol microphysics modules which are currently available for the climate model ECHAM5.

  3. Effects of Hydrodynamic Interaction in Aerosol Particle Settling: Mesoscopic Particle-level Full Dynamics Simulations

    NASA Astrophysics Data System (ADS)

    Li, Shuiqing; Yang, Mengmeng; Marshall, Jeffrey

    2014-11-01

    A new mesoscopic particle-level approach is developed for the full dynamics simulation (FDS) of the settling of systems of aerosol micro-particles. The approach efficiently combines an adhesive discrete-element method for particle motions and an Oseen dynamics method for hydrodynamic interactions. Compared to conventional Stokeslet and Oseenlet simulations, the FDS not only accounts for the cloud-scale fluid inertia effect and the particle inertia effect, but also overcomes the singularity problem using a soft-sphere model of adhesive contact. The effect of hydrodynamic interactions is investigated based on FDS results. The particle inertia is found to reduce the mobility of particle clouds and to elongate the cloud on vertical direction. Meanwhile, the fluid inertia decreases the settling velocity by weakening the hydrodynamic interaction and tends to flatten the cloud, leading to breakup. Expressions for the settling velocity of particle cloud are proposed with consideration of fluid inertia effect and the cloud shape. Finally, the transformation in settling behavior from a finite particle cloud to an unbounded uniform suspension is explained. This work has been funded by the National Natural Science Funds of China (No. 50976058), and by the National Key Basic Research and Development Program (2013CB228506).

  4. Propagation of global model uncertainties in aerosol forecasting: A field practitioner's opinion

    NASA Astrophysics Data System (ADS)

    Reid, J. S.; Benedetti, A.; Bozzo, A.; Brooks, I. M.; Brooks, M.; Colarco, P. R.; daSilva, A.; Flatau, M. K.; Kuehn, R.; Hansen, J.; Holz, R.; Kaku, K.; Lynch, P.; Remy, S.; Rubin, J. I.; Sekiyama, T. T.; Tanaka, T. Y.; Zhang, J.

    2015-12-01

    While aerosol forecasting has its own host of aerosol source, sink and microphysical challenges to overcome, ultimately any numerical weather prediction based aerosol model can be no better than its underlying meteorology. However, the scorecard elements that drive NWP model development have varying relationships to the key uncertainties and biases that are of greatest concern to aerosol forecasting. Here we provide opinions from member developers of the International Cooperative for Aerosol Prediction (ICAP) on NWP deficiencies related to multi-specie aerosol forecasting, as well as relevance of current NWP scorecard elements to aerosol forecasting. Comparisons to field mission data to simulations are used to demonstrate these opinions and show how shortcomings in individual processes in the global models cascade into aerosol prediction. While a number of sensitivities will be outlined, as one would expect, the most important processes relate to aerosol sources, sinks and, in the context of data assimilation, aerosol hygroscopicity. Thus, the pressing needs in the global models relate to boundary layer and convective processes in the context of large scale waves. Examples will be derived from tropical to polar field measurements, from simpler to more complex including a) network data on dust emissions and transport from Saharan Africa, b) boundary layer development, instability, and deep convection in the United States during Studies of Emissions and Atmospheric, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS); and c) 7 Southeast Asian Studies (7SEAS) data on aerosol influences by maritime convection up-scaled through tropical waves. While the focus of this talk is how improved meteorological model processes are important to aerosol modeling, we conclude with recent findings of the Arctic Summer Cloud Ocean Study (ASCOS) which demonstrate how aerosol processes may be important to global model simulations of polar cloud, surface energy and subsequently

  5. Large-Scale Aerosol Modeling and Analysis

    DTIC Science & Technology

    2010-09-30

    advance anywhere on the globe. NAAPS and COAMPS are particularly useful for forecasts of dust storms in areas downwind of the large deserts of the world... dust source regions in NAAPS. The DSD has been crucial for high-resolution dust forecasting in SW Asia using COAMPS (Walker et al., 2009). Dust ...6 Figure 2. Four-panel product used to compare multiple model forecasts of visibility in SW Asia dust storms . On the web the product is

  6. Simulation of Aerosols and Chemistry with a Unified Global Model

    NASA Technical Reports Server (NTRS)

    Chin, Mian

    2004-01-01

    This project is to continue the development of the global simulation capabilities of tropospheric and stratospheric chemistry and aerosols in a unified global model. This is a part of our overall investigation of aerosol-chemistry-climate interaction. In the past year, we have enabled the tropospheric chemistry simulations based on the GEOS-CHEM model, and added stratospheric chemical reactions into the GEOS-CHEM such that a globally unified troposphere-stratosphere chemistry and transport can be simulated consistently without any simplifications. The tropospheric chemical mechanism in the GEOS-CHEM includes 80 species and 150 reactions. 24 tracers are transported, including O3, NOx, total nitrogen (NOy), H2O2, CO, and several types of hydrocarbon. The chemical solver used in the GEOS-CHEM model is a highly accurate sparse-matrix vectorized Gear solver (SMVGEAR). The stratospheric chemical mechanism includes an additional approximately 100 reactions and photolysis processes. Because of the large number of total chemical reactions and photolysis processes and very different photochemical regimes involved in the unified simulation, the model demands significant computer resources that are currently not practical. Therefore, several improvements will be taken, such as massive parallelization, code optimization, or selecting a faster solver. We have also continued aerosol simulation (including sulfate, dust, black carbon, organic carbon, and sea-salt) in the global model to cover most of year 2002. These results have been made available to many groups worldwide and accessible from the website http://code916.gsfc.nasa.gov/People/Chin/aot.html.

  7. Thermal dynamic modeling study

    NASA Technical Reports Server (NTRS)

    Ojalvo, I. U.

    1972-01-01

    Some thermal dynamic requirements associated with the space shuttle vehicle are reviewed. Pertinent scaling laws are discussed and recommendations are offered regarding the need for conducting reduced-scale dynamic tests of major components at elevated temperatures. Items considered are the development and interpretation of thermal dynamic structural scaling laws, the identification of major related problem areas and a presentation of viable model fabrication, instrumentation, and test procedures.

  8. Radiative forcing by stratospheric aerosol in a CCM with interactive aerosol module

    NASA Astrophysics Data System (ADS)

    Brühl, Christoph; Lelieveld, Jos; Tost, Holger; Steil, Benedikt; Höpfner, Michael

    2013-04-01

    Multiyear studies with the atmospheric chemistry general circulation model EMAC with the aerosol module GMXe demonstrate that stratospheric aerosol formation is controlled by COS oxidation and SO2 injected by low-latitude volcanic eruptions. The model consistently uses the same parameters in the troposphere and stratosphere for 7 aerosol modes applied. Calculated radiative heating by aerosol feeds back to stratospheric dynamics. Radiative forcing by stratospheric aerosol can be diagnosed separately. The simulations include the medium size tropical eruptions in 2003, 2005 and 2006 but also the major eruption of Pinatubo in 1991. We show that calculated radiative forcing by stratospheric aerosol agrees well with the corresponding satellite derived quantity and that the medium size tropical eruptions should not be neglected in climate simulations. Changes in temperature, dynamics and tracer transport due to interactive aerosol will be also presented. We show also that calculated aerosol and SO2 concentrations are consistent with the observations by SAGE and by MIPAS on ENVISAT.

  9. Regional simulation of aerosol radiative effects and their influence on rainfall over India using WRFChem model

    NASA Astrophysics Data System (ADS)

    Kedia, Sumita; Cherian, Ribu; Islam, Sahidul; Das, Subrata Kumar; Kaginalkar, Akshara

    2016-12-01

    A regional climate model, WRFChem has been utilized to simulate aerosol and rainfall distribution over India during July 2010 which was a normal monsoon year. Two identical simulations, one includes aerosol feedback via their direct and indirect effects and other one without any aerosol effect, are structured to understand the impact of aerosol net (direct + indirect) effect on rainfall pattern over India. Model results are accompanied by satellite and ground based observations to examine the robustness of the model simulations. It is shown that the model can reproduce the spatial and temporal characteristics of meteorological parameters, rainfall distribution, aerosol optical depth and single scattering albedo reasonably well. Model simulated spatial distribution and magnitude of aerosol optical depth over India are realistic, particularly over northwest India, where mineral dust is a major contributor to the total aerosol loading and over Indo-Gangetic Plain region (IGP) where AOD remains high throughout the year. Net (shortwave + longwave) atmospheric heating rate is the highest (> 0.27 K day - 1) over east IGP due to abundant dust and anthropogenic aerosols while it is the lowest over peninsular India and over the Thar desert (< 0.03 K day - 1) which can be attributed to less aerosol concentration and longwave cooling, respectively. It is shown that, inclusion of aerosol direct and indirect effects have strong influence ( ± 20%) on rainfall magnitude and its distribution over Indian subcontinent during monsoon.

  10. Modeling the Big Bend Regional Aerosol and Visibility Observational (BRAVO) Study using CMAQ-MADRID

    NASA Astrophysics Data System (ADS)

    Knipping, E. M.; Kumar, N.; Pun, B.; Wu, S.; Seigneur, C.

    2003-12-01

    A scientifically rigorous treatment of particulate matter within the framework of the Community Multiscale Air Quality (CMAQ) model is provided by CMAQ-MADRID (Model for Aerosol Dynamics, Reaction, Ionization, and Dissolution). CMAQ-MADRID is used to simulate the fate and transport of ambient gases and particulate matter (PM) during the Big Bend Regional Aerosol and Visibility Observational (BRAVO) study. The configuration of CMAQ-MADRID used for this study comprises the Regional Acid Deposition Mechanism v.2 (RADM2) gas-phase chemistry mechanism, a sectional PM solver incorporating the ISORROPIA inorganic thermodynamics module and the AER/EPRI/Caltech (AEC) secondary organic aerosol (SOA) module, and the Carnegie Mellon University (CMU) cloud chemistry module. Boundary conditions for gas- and particle-phase species are prescribed by an outer domain simulated using the Regional Modeling System for Aerosols and Deposition REMSAD (whose domain comprises most of North America). Sulfur dioxide (SO2) and particulate sulfate boundary conditions for the REMSAD domain are provided by the Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation Transport (GOCART) model. Concentrations of sulfur dioxide and particulate sulfate at the CMAQ boundary are scaled to observations from monitoring stations of the Clean Air Status and Trends Network (CASTNet) and Interagency Monitoring of Protected Visual Environments (IMPROVE) network. The performance of CMAQ-MADRID is evaluated by comparing predictions with field measurements of the principal components contributing to visibility degradation: salts of ammonium with sulfate and nitrate, organic mass, elemental carbon and "other" particulate matter constituents, e.g. dust, sea salt and metal oxides. Model performance with respect to sulfate predictions, including model performance for its gas-phase precursor, sulfur dioxide, is explored across the thirty-seven stations comprising the BRAVO Network. The performance of CMAQ

  11. Modelling aerosol processes related to the atmospheric dispersion of sarin.

    PubMed

    Kukkonen, J; Riikonen, K; Nikmo, J; Jäppinen, A; Nieminen, K

    2001-08-17

    We have developed mathematical models for evaluating the atmospheric dispersion of selected chemical warfare agents (CWA), including the evaporation and settling of contaminant liquid droplets. The models and numerical results presented may be utilised for designing protection and control measures against the conceivable use of CWA's. The model AERCLOUD (AERosol CLOUD) was extended to treat two nerve agents, sarin and VX, and the mustard agent. This model evaluates the thermodynamical evolution of a five-component aerosol mixture, consisting of two-component droplets together with the surrounding three-component gas. We have performed numerical computations with this model on the evaporation and settling of airborne sarin droplets in characteristic dispersal and atmospheric conditions. In particular, we have evaluated the maximum radii (r(M)) of a totally evaporating droplet, in terms of the ambient temperature and contaminant vapour concentration. The radii r(M) range from approximately 15-80 microm for sarin droplets for the selected ambient conditions and initial heights. We have also evaluated deposition fractions in terms of the initial droplet size.

  12. A full spectral cumulus cloud parameterisation including aerosol effects: The Convective Cloud Field Model (CCFM)

    NASA Astrophysics Data System (ADS)

    Wagner, T. M.; Graf, H. F.; Yano, J. I.

    2009-04-01

    The convective cloud field model is a convection parameterisation based on the representation of a full cumulus cloud spectrum using a dynamical quasi-equilibrium closure. It employs a one dimensional entraining parcel model whose properties are simulated on a refined vertical resolution (~100 m) in order to capture the complex cloud microphysical processes in convective clouds. We introduced an enhanced microphysics compared to those currently used in convection parameterisations, containing warm and mixed phase cloud microphysics processes and incorporates aerosol effects by linking the cloud droplet number concentration to the aerosol amount. Similar to the Arakawa and Schubert (1974) quasi-equilibrium closure we allow for the mutual influence of clouds via the environment. Instead of assuming instantaneous stabilisation of the environment though, the clouds are dynamically interacting for the length of the large scale model time step without necessarily adopting an equilibrium situation. The model is evaluated in single column mode (SCM) for continental and tropical convection using the ARM SGP and TWP-ICE cases. Moreover it is evaluated in global mode using the global atmospheric circulation model ECHAM5. For the SCM cases the precipitation, heating and moistening rates for the simulated period is better represented than with the Tiedtke massflux scheme which is the usual convection parameterisation within ECHAM5. Moreover, we find a clear response to an enhanced aerosol loading which generally leads to a reduction of convective precipitation. Globally, the CCFM produces slightly higher convective precipitation rates and especially responds better to convective instability over lower latitudes and the storm track regions.

  13. Aerosol data assimilation in the chemical transport model MOCAGE during the TRAQA/ChArMEx campaign: aerosol optical depth

    NASA Astrophysics Data System (ADS)

    Sič, Bojan; El Amraoui, Laaziz; Piacentini, Andrea; Marécal, Virginie; Emili, Emanuele; Cariolle, Daniel; Prather, Michael; Attié, Jean-Luc

    2016-11-01

    In this study, we describe the development of the aerosol optical depth (AOD) assimilation module in the chemistry transport model (CTM) MOCAGE (Modèle de Chimie Atmosphérique à Grande Echelle). Our goal is to assimilate the spatially averaged 2-D column AOD data from the National Aeronautics and Space Administration (NASA) Moderate-resolution Imaging Spectroradiometer (MODIS) instrument, and to estimate improvements in a 3-D CTM assimilation run compared to a direct model run. Our assimilation system uses 3-D-FGAT (first guess at appropriate time) as an assimilation method and the total 3-D aerosol concentration as a control variable. In order to have an extensive validation dataset, we carried out our experiment in the northern summer of 2012 when the pre-ChArMEx (CHemistry and AeRosol MEditerranean EXperiment) field campaign TRAQA (TRAnsport à longue distance et Qualité de l'Air dans le bassin méditerranéen) took place in the western Mediterranean basin. The assimilated model run is evaluated independently against a range of aerosol properties (2-D and 3-D) measured by in situ instruments (the TRAQA size-resolved balloon and aircraft measurements), the satellite Spinning Enhanced Visible and InfraRed Imager (SEVIRI) instrument and ground-based instruments from the Aerosol Robotic Network (AERONET) network. The evaluation demonstrates that the AOD assimilation greatly improves aerosol representation in the model. For example, the comparison of the direct and the assimilated model run with AERONET data shows that the assimilation increased the correlation (from 0.74 to 0.88), and reduced the bias (from 0.050 to 0.006) and the root mean square error in the AOD (from 0.12 to 0.07). When compared to the 3-D concentration data obtained by the in situ aircraft and balloon measurements, the assimilation consistently improves the model output. The best results as expected occur when the shape of the vertical profile is correctly simulated by the direct model. We

  14. Tropospheric aerosol size distributions simulated by three online global aerosol models using the M7 microphysics module

    SciTech Connect

    Zhang, Kai; Wan, Hui; Wang, Bin; Zhang, Meigen; Feichter, J.; Liu, Xiaohong

    2010-07-14

    Tropospheric aerosol size distributions are simulated by three online global models that employ exactly the same modal approach but differ in many aspects such as model meteorology, natural aerosol emissions, sulfur chemistry, and the parameterization of deposition processes. The main purpose of this study is to identify where the largest inter-model discrepancies occur and what the main reasons are. The number concentrations of different aerosol size ranges are compared among the three models and against observations. Overall all the three models can capture the basic features of the observed aerosol number spatial distributions. The magnitude of the number concentration of each mode is consistent among the three models. Quantitative differences are also clearly detectable. For the soluble and insoluble coarse mode and accumulation mode, inter-model discrepancies mainly result from differences in the sea salt and dust emissions, as well as the different strengths of the convective transport in the meteorological models. For the nucleation mode and the soluble Aitken mode, the spread of the model results is largest in the tropics and in the middle and upper troposphere. Diagnostics and sensitivity experiments suggest that this large spread is closely related to the sulfur cycle in the models, which is strongly affected by the choice of sulfur chemistry scheme, its coupling with the convective transport and wet deposition calculation, and the related meteorological fields such as cloud cover, cloud water content, and precipitation. The aerosol size distributions simulated by the three models are compared to observations in the boundary layer. The characteristic shape and magnitude of the distribution functions are reasonably reproduced in typical conditions (i.e., clean, polluted and transition areas). Biases in the mode parameters over the remote oceans and the China adjacent seas are probably caused by the fixed mode variance in the mathematical formulations used

  15. Tropospheric aerosol size distributions simulated by three online global aerosol models using the M7 microphysics module

    NASA Astrophysics Data System (ADS)

    Zhang, K.; Wan, H.; Wang, B.; Zhang, M.; Feichter, J.; Liu, X.

    2010-03-01

    Tropospheric aerosol size distributions are simulated by three online global models that employ exactly the same modal approach but differ in many aspects such as model meteorology, natural aerosol emissions, sulfur chemistry, and the parameterization of deposition processes. The main purpose of this study is to identify where the largest inter-model discrepancies occur and what the main reasons are. The number concentrations of different aerosol size ranges are compared among the three models and against observations. Overall all the three models can capture the basic features of the observed aerosol number spatial distributions. The magnitude of the number concentration of each mode is consistent among the three models. Quantitative differences are also clearly detectable. For the soluble and insoluble coarse mode and accumulation mode, inter-model discrepancies mainly result from differences in the sea salt and dust emissions, as well as the different strengths of the convective transport in the meteorological models. For the nucleation mode and the soluble Aitken mode, the spread of the model results is largest in the tropics and in the middle and upper troposphere. Diagnostics and sensitivity experiments suggest that this large spread is closely related to the sulfur cycle in the models, which is strongly affected by the choice of sulfur chemistry scheme, its coupling with the convective transport and wet deposition calculation, and the related meteorological fields such as cloud cover, cloud water content, and precipitation. The aerosol size distributions simulated by the three models are compared to observations in the boundary layer. The characteristic shape and magnitude of the distribution functions are reasonably reproduced in typical conditions (i.e., clean, polluted and transition areas). Biases in the mode parameters over the remote oceans and the China adjacent seas are probably caused by the fixed mode variance in the mathematical formulations used

  16. Modeling Organic Aerosols during MILAGRO: Application of the CHIMERE Model and Importance of Biogenic Secondary Organic Aerosols

    SciTech Connect

    Hodzic, Alma; Jimenez, Jose L.; Madronich, Sasha; Aiken, Allison; Bessagnet, Bertrand; Curci, Gabriele; Fast, Jerome D.; Lamarque, J.-F.; Onasch, Timothy B.; Roux, Gregory; Schauer, James J.; Stone, Elizabeth A.

    2009-09-22

    The meso-scale chemistry-transport model CHIMERE is used to assess our understanding of major sources and formation processes leading to a fairly large amount of organic aerosols [OA, including primary OA (POA) and secondary OA (SOA)] observed in Mexico City during the MILAGRO field project (March 2006). Chemical analyses of submicron aerosols from aerosol mass spectrometers (AMS) indicate that organic particles found in the Mexico City basin have a large fraction of oxygenated organic species (OOA), which have strong correspondence with SOA, and that their production actively continues downwind of the city. The SOA formation is modeled here by the first-generation oxidation of anthropogenic (i.e., aromatics, alkanes) and biogenic (i.e., monoterpenes and isoprene) precursors and their partitioning into both organic and aqueous phases. The near-surface model evaluation shows that predicted OA correlates reasonably well with measurements during the campaign, however it remains a factor of 2 lower than the measured total OA. Fairly good agreement is found between predicted and observed POA within the city suggesting that anthropogenic and biomass burning emissions are reasonably captured. Consistent with previous studies in Mexico City, large discrepancies are encountered for SOA species, with a factor of 5-10 model underestimate. When only anthropogenic SOA precursors were considered, the model was able to reproduce within a factor of two the sharp increase in SOA concentrations during the late morning at both urban and near-urban locations. However, predicted SOA concentrations were unrealistically low when photochemistry was not active, especially overnight. These nighttime discrepancies were not significantly reduced when greatly enhanced partitioning to the aerosol phase was assumed. Model sensitivity results suggest that observed nighttime SOA concentrations are strongly influenced by the regional background (~2µg/m3) from biogenic origin, which is transported

  17. Aerosol effect on the warm rain formation process: Satellite observations and modeling

    NASA Astrophysics Data System (ADS)

    Suzuki, Kentaroh; Stephens, Graeme L.; Lebsock, Matthew D.

    2013-01-01

    This study demonstrates how aerosols influence the liquid precipitation formation process. This demonstration is provided by the combined use of satellite observations and global high-resolution model simulations. Methodologies developed to examine the warm cloud microphysical processes are applied to both multi-sensor satellite observations and aerosol-coupled global cloud-resolving model (GCRM) results to illustrate how the warm rain formation process is modulated under different aerosol conditions. The observational analysis exhibits process-scale signatures of rain suppression due to increased aerosols, providing observational evidence of the aerosol influence on precipitation. By contrast, the corresponding statistics obtained from the model show a much faster rain formation even for polluted aerosol conditions and much weaker reduction of precipitation in response to aerosol increase. It is then shown that this reduced sensitivity points to a fundamental model bias in the warm rain formation process that in turn biases the influence of aerosol on precipitation. A method of improving the model bias is introduced in the context of a simplified single-column model (SCM) that represents the cloud-to-rain water conversion process in a manner similar to the original GCRM. Sensitivity experiments performed by modifying the model assumptions in the SCM and their comparisons to satellite statistics both suggest that the auto-conversion scheme has a critical role in determining the precipitation response to aerosol perturbations and also provide a novel way of constraining key parameters in the auto-conversion schemes of global models.

  18. Modeling Climate Dynamically

    ERIC Educational Resources Information Center

    Walsh, Jim; McGehee, Richard

    2013-01-01

    A dynamical systems approach to energy balance models of climate is presented, focusing on low order, or conceptual, models. Included are global average and latitude-dependent, surface temperature models. The development and analysis of the differential equations and corresponding bifurcation diagrams provides a host of appropriate material for…

  19. Intercomparison of aerosol microphysics modules in the framework of the ECHAM5 climate model

    NASA Astrophysics Data System (ADS)

    Hommel, R.; Kokkola, H.; Kazil, J.; Niemeier, U.; Partanen, A. I.; Feichter, J.; Timmreck, C.

    2009-04-01

    Aerosols in the atmosphere are an elementary constituent of the atmospheric composition and affect the global climate through a variety of physical and chemical interactions in the troposphere and stratosphere. Large volcanic eruptions alter the Earth's radiative balance and interfere with the catalytic cycles of ozone depletion mainly by the formation of micrometer size aerosol particles above the tropopause. Recent experimental and numerical investigations of process oriented aerosol-climate interactions revealed that appropriate climate effects can only be modeled when informations about the aerosol size and number spectra are provided. Nevertheless in the majority of climate models volcanic perturbations of the stratosphere are either prescribed based on the aerosol parameters of interested (surface area, optical depth) or the aerosol microphysics is considered explicitly but with a heavily reduced number of degrees of freedom. This yields e.g. to underestimations of surface temperature effects in the fade of an eruption. To overcome that weakness, we tested three aerosol modules currently available in the framework of the climate model ECHAM5 in environmental conditions assumed to be representative in the stratosphere after the injection of SO2 from modest to large volcanic eruptions. The study focuses on the evolution of liquid H2SO4/H2O aerosol. The modal modal M7, currently the default aerosol scheme in ECHAM5, is compared with two sectional aerosol schemes: the moving centre sectional aerosol scheme SALSA, and the fixed sectional scheme SAM2. Since direct measurements of particle size informations during the initial stage of a volcanic injection in the stratosphere are not available, the detailed sectional aerosol model MAIA is used as a reference in this study. It is shown that all modules are able to represent a "typical" stratospheric background aerosol distribution when the particles are formed via the oxidation pathway of SO2. However, the modules

  20. Verification of the naval oceanic vertical aerosol model during FIRE

    NASA Technical Reports Server (NTRS)

    Davidson, K. L.; Deleeuw, G.; Gathman, S. G.; Jensen, D. R.

    1990-01-01

    The value of Naval Oceanic Vertical Aerosol Model (NOVAM) is illustrated for estimating the non-uniform and non-logarithmic extinction profiles, based on a severe test involving conditions close to and beyond the limits of applicability of NOVAM. A more comprehensive evaluation of NOVAM from the FIRE data is presented, which includes a clear-air case. For further evaluation more data are required on the vertical structure of the extinction in the marine atmospheric boundary layer (MABL), preferably for different meteorological conditions and in different geographic areas (e.g., ASTEX).

  1. Modeling the aerosols in the atmosphere of Titan

    NASA Astrophysics Data System (ADS)

    Thomas-Osip, Joanna Elizabeth

    2001-09-01

    A combination of laboratory experiments, theoretical modeling, and spacecraft in situ observations is employed to characterize the aerosols in the atmosphere of Titan. The scattering properties of model aerosols were measured using the Microwave Analog Light Scattering Facility at the University of Florida and complemented with theoretical modeling of single scattering characteristics and radiative transfer in Titan's atmosphere. This study compares these modeling results with photopolarimetric observations made over a range of phase angles by the Pioneer 11 and Voyagers 1 and 2 spacecraft approximately 20 years ago. Important results of this work include a survey of the scattering properties of different particle shapes necessary to accurately interpret these observations without introducing non-physical assumptions about the particles or requiring additional free parameters to the radiative transfer models. Previous studies use calculation methods which, due to computing memory and processing time requirements, a priori exclude much of the phase space that the microwave analog laboratory is ideal for exploring. The goal of the present work, to directly constrain aerosol physical characteristics, is addressed by studying in a consistent manner how a variety of particle morphologies affect polarization and intensity measurements of Titan's atmosphere. Single liquid drops are modeled using spheres for which scattering patterns can be easily calculated with Mie theory. Cubes are used as a representation of solids with sharp edges due to fragmentation. More complex particle morphologies are modeled as aggregates that are likely formed by collisions between semi-liquid spheres that stick together instead of merging. Radiative transfer calculations for model atmospheres containing these particles are constrained by direct comparison to in situ spacecraft observations. Based on these comparisons, many model morphologies are excluded from further consideration and the

  2. Characterize Aerosols from MODIS MISR OMI MERRA-2: Dynamic Image Browse Perspective

    NASA Technical Reports Server (NTRS)

    Wei, Jennifer; Yang, Wenli; Albayrak, Arif; Zhao, Peisheng; Zeng, Jian; Shen, Suhung; Johnson, James; Kempler, Steve

    2016-01-01

    Among the known atmospheric constituents, aerosols still represent the greatest uncertainty in climate research. To understand the uncertainty is to bring altogether of observational (in-situ and remote sensing) and modeling datasets and inter-compare them synergistically for a wide variety of applications that can bring far-reaching benefits to the science community and the broader society. These benefits can best be achieved if these earth science data (satellite and modeling) are well utilized and interpreted. Unfortunately, this is not always the case, despite the abundance and relative maturity of numerous satellite-borne sensors routinely measure aerosols. There is often disagreement between similar aerosol parameters retrieved from different sensors, leaving users confused as to which sensors to trust for answering important science questions about the distribution, properties, and impacts of aerosols. NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) have developed a new visualization service (NASA Level 2 Data Quality Visualization, DQViz)supporting various visualization and data accessing capabilities from satellite Level 2(MODISMISROMI) and long term assimilated aerosols from NASA Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2 displaying at their own native physical-retrieved spatial resolution. Functionality will include selecting data sources (e.g., multiple parameters under the same measurement), defining area-of-interest and temporal extents, zooming, panning, overlaying, sliding, and data subsetting and reformatting.

  3. Increase of Cloud Droplet Size with Aerosol Optical Depth: An Observational and Modeling Study

    SciTech Connect

    Yuan, Tianle; Li, Zhanqing; Zhang, Renyi; Fan, Jiwen

    2008-02-21

    Cloud droplet effective radius (DER) is generally negatively correlated with aerosol optical depth (AOD) as a proxy of cloud condensation nuclei. In this study, cases of positive correlation were found over certain portions of the world by analyzing the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite products, together with a general finding that DER may increase or decrease with aerosol loading depending on environmental conditions. The slope of the correlation between DER and AOD is driven primarily by water vapor amount, which explains 70% of the variance in our study. Various potential artifacts that may cause the positive relation are investigated including water vapor swelling, partially cloudy, atmospheric dynamics, cloud three-dimensional (3-D) and surface influence effects. None seems to be the primary cause for the observed phenomenon, although a certain degree of influence exists for some of the factors. Analyses are conducted over seven regions around the world representing different types of aerosols and clouds. Only two regions show positive dependence of DER on AOD, near coasts of the Gulf of Mexico and South China Sea, which implies physical processes may at work. Using a 2-D spectral-bin microphysics Goddard Cumulus Ensemble model (GCE) which incorporated a reformulation of the Köhler theory, two possible physical mechanisms are hypothesized. They are related to the effects of slightly soluble organics (SSO) particles and giant CCNs. Model simulations show a positive correlation between DER and AOD, due to a decrease in activated aerosols with an increasing SSO content. Addition of a few giant CCNs also increases the DER. Further investigations are needed to fully understand and clarify the observed phenomenon.

  4. Dynamic model for biospeckle.

    PubMed

    Paixão, Crysttian Arantes; da Costa, Antonio Tavares

    2013-06-01

    This paper reports the development of a simple dynamic microscopic model to describe the main features of the phenomenon known as dynamic speckle, or biospeckle. Biospeckle is an interference pattern formed when a biological surface is illuminated with coherent light. The dynamic characteristics of biospeckle have been investigated as possible tools for assessing the quality of biological products. Our model, despite its simplicity, was able to reproduce qualitatively the main features of biospeckle. We were able to correlate variations in a microscopic parameter associated with movement of the particles comprising the organic surface with changes in a macroscopic parameter that measures the change rate of a dynamic interference pattern. We showed that this correlation occurs only within a limited range of parameter microscope values. We also showed how our model was able to describe nonuniform surfaces composed of more than one type of particles.

  5. The role of aerosols in cloud drop parameterizations and its applications in global climate models

    SciTech Connect

    Chuang, C.C.; Penner, J.E.

    1996-04-01

    The characteristics of the cloud drop size distribution near cloud base are initially determined by aerosols that serve as cloud condensation nuclei and the updraft velocity. We have developed parameterizations relating cloud drop number concentration to aerosol number and sulfate mass concentrations and used them in a coupled global aerosol/general circulation model (GCM) to estimate the indirect aerosol forcing. The global aerosol model made use of our detailed emissions inventories for the amount of particulate matter from biomass burning sources and from fossil fuel sources as well as emissions inventories of the gas-phase anthropogenic SO{sub 2}. This work is aimed at validating the coupled model with the Atmospheric Radiation Measurement (ARM) Program measurements and assessing the possible magnitude of the aerosol-induced cloud effects on climate.

  6. Modeling the chemistry of the marine boundary layer: Sulphate formation and the role of sea-salt aerosol particles

    NASA Astrophysics Data System (ADS)

    van den Berg, Ad; Dentener, Frank; Lelieveld, Jos

    2000-05-01

    A one-dimensional model is presented that interactively simulates the dynamics and the gas-aqueous phase chemistry of the cloud-topped marine boundary layer. The model is described and tested using observations from the Atlantic Stratocumulus Transition Experiment/Marine Aerosol and Gas Exchange (ASTEX/MAGE) measurement campaign. The comparison generally indicates satisfactory agreement for dynamical properties and chemical species, except for SO2. We present several explanations for this discrepancy. However, a conclusive account is dependent on quantitative information about free tropospheric SO2 and H2O2 that is not available. Furthermore, a series of sensitivity runs is presented to explain the large quantities of non-sea-salt sulphate associated with sea-salt particles, as observed during ASTEX/MAGE. The main conclusions are that most sulphate associated with sea-salt particles is formed in cloud droplets that subsequently evaporate and that only a small amount is formed in deliquesced aerosol particles. The model results are sensitive to changes in the assumed sea-salt emission rate and the overall aerosol size distribution. The latter indicates that a shift in the sea-salt aerosol distribution toward the smaller particle sizes might explain the observed amount of sulphate associated with sea-salt particles.

  7. Assimilation of Aerosols from Biomass Burning by the Radiative Transfer Model Brasil-Sr

    NASA Astrophysics Data System (ADS)

    Costa, R. S.; Gonçalves, A. R.; Souza, J. G.; Martins, F. R.; Pereira, E. B.

    2015-12-01

    The radiative transfer model BRASIL-SR is the main tool used by the Earth System Science Centre from the National Institute for Space Research (CCST / INPE) for solar energy resource assessment. Due to large and frequent events of burning biomass in Brazil there is a need to improve the aerosol representation in this model, mainly during the dry season (September - November) in Northern and Central Brazil. The standard aerosol representation in this model is inadequate to capture these events. It is based on the mean monthly climatological horizontal visibility with latitudinal values based on coarse global observation data. To improve the aerosol representation, climatological data of daily horizontal visibility from National Institute of Meteorology (INMET) was used to generate monthly averages from 1999 to 2012. To do a better representation of aerosols from burning biomass events, from megacities aerosol generation, and from transport processes, horizontal visibility estimates performed using aerosol optical thickness at 550 nm data from MACC Project Reanalysis model were used to adjust the aerosol representation in regions were the simple horizontal visibility fails. A methodology to generate these new visibility data from the Reanalysis was made and the resulting data was compared with the average horizontal visibility to implement a new corrected database. The solar irradiation simulated by the model using this new aerosol representation proved to be better than the previous version of the model in all regions with high aerosol loading.

  8. Impacts of increasing the aerosol complexity in the Met Office global numerical weather prediction model

    NASA Astrophysics Data System (ADS)

    Mulcahy, J. P.; Walters, D. N.; Bellouin, N.; Milton, S. F.

    2014-05-01

    The inclusion of the direct and indirect radiative effects of aerosols in high-resolution global numerical weather prediction (NWP) models is being increasingly recognised as important for the improved accuracy of short-range weather forecasts. In this study the impacts of increasing the aerosol complexity in the global NWP configuration of the Met Office Unified Model (MetUM) are investigated. A hierarchy of aerosol representations are evaluated including three-dimensional monthly mean speciated aerosol climatologies, fully prognostic aerosols modelled using the CLASSIC aerosol scheme and finally, initialised aerosols using assimilated aerosol fields from the GEMS project. The prognostic aerosol schemes are better able to predict the temporal and spatial variation of atmospheric aerosol optical depth, which is particularly important in cases of large sporadic aerosol events such as large dust storms or forest fires. Including the direct effect of aerosols improves model biases in outgoing long-wave radiation over West Africa due to a better representation of dust. However, uncertainties in dust optical properties propagate to its direct effect and the subsequent model response. Inclusion of the indirect aerosol effects improves surface radiation biases at the North Slope of Alaska ARM site due to lower cloud amounts in high-latitude clean-air regions. This leads to improved temperature and height forecasts in this region. Impacts on the global mean model precipitation and large-scale circulation fields were found to be generally small in the short-range forecasts. However, the indirect aerosol effect leads to a strengthening of the low-level monsoon flow over the Arabian Sea and Bay of Bengal and an increase in precipitation over Southeast Asia. Regional impacts on the African Easterly Jet (AEJ) are also presented with the large dust loading in the aerosol climatology enhancing of the heat low over West Africa and weakening the AEJ. This study highlights the

  9. Impacts of increasing the aerosol complexity in the Met Office global NWP model

    NASA Astrophysics Data System (ADS)

    Mulcahy, J. P.; Walters, D. N.; Bellouin, N.; Milton, S. F.

    2013-11-01

    Inclusion of the direct and indirect radiative effects of aerosols in high resolution global numerical weather prediction (NWP) models is being increasingly recognised as important for the improved accuracy of short-range weather forecasts. In this study the impacts of increasing the aerosol complexity in the global NWP configuration of the Met Office Unified Model (MetUM) are investigated. A hierarchy of aerosol representations are evaluated including three dimensional monthly mean speciated aerosol climatologies, fully prognostic aerosols modelled using the CLASSIC aerosol scheme and finally, initialised aerosols using assimilated aerosol fields from the GEMS project. The prognostic aerosol schemes are better able to predict the temporal and spatial variation of atmospheric aerosol optical depth, which is particularly important in cases of large sporadic aerosol events such as large dust storms or forest fires. Including the direct effect of aerosols improves model biases in outgoing longwave radiation over West Africa due to a better representation of dust. However, uncertainties in dust optical properties propogate to its direct effect and the subsequent model response. Inclusion of the indirect aerosol effects improves surface radiation biases at the North Slope of Alaska ARM site due to lower cloud amounts in high latitude clean air regions. This leads to improved temperature and height forecasts in this region. Impacts on the global mean model precipitation and large-scale circulation fields were found to be generally small in the short range forecasts. However, the indirect aerosol effect leads to a strengthening of the low level monsoon flow over the Arabian Sea and Bay of Bengal and an increase in precipitation over Southeast Asia. Regional impacts on the African Easterly Jet (AEJ) are also presented with the large dust loading in the aerosol climatology enhancing of the heat low over West Africa and weakening the AEJ. This study highlights the importance

  10. An aerosol challenge model of tuberculosis in Mauritian cynomolgus macaques

    PubMed Central

    Sharpe, S. A.; White, A. D.; Sibley, L.; Gleeson, F.; Hall, G. A.; Basaraba, R. J.; McIntyre, A.; Clark, S. O.; Gooch, K.; Marsh, P. D.; Williams, A.; Dennis, M. J.

    2017-01-01

    Background New interventions for tuberculosis are urgently needed. Non-human primate (NHP) models provide the most relevant pre-clinical models of human disease and play a critical role in vaccine development. Models utilising Asian cynomolgus macaque populations are well established but the restricted genetic diversity of the Mauritian cynomolgus macaques may be of added value. Methods Mauritian cynomolgus macaques were exposed to a range of doses of M. tuberculosis delivered by aerosol, and the outcome was assessed using clinical, imaging and pathology-based measures. Results All macaques developed characteristic clinical signs and disease features of tuberculosis (TB). Disease burden and the ability to control disease were dependent on exposure dose. Mauritian cynomolgus macaques showed less variation in pulmonary disease burden and total gross pathology scores within exposure dose groups than either Indian rhesus macaques or Chinese cynomolgus macaques Conclusions The genetic homogeneity of Mauritian cynomolgus macaques makes them a potentially useful model of human tuberculosis. PMID:28273087

  11. Aerosol-CFD modelling of ultrafine and black carbon particle emission, dilution, and growth near roadways

    NASA Astrophysics Data System (ADS)

    Huang, L.; Gong, S. L.; Gordon, M.; Liggio, J.; Staebler, R. M.; Stroud, C. A.; Lu, G.; Mihele, C.; Brook, J. R.; Jia, C. Q.

    2014-05-01

    Many studies have shown that on-road vehicle emissions are the dominant source of ultrafine particles (UFP; diameter < 100 nm) in urban areas and near-roadway environments. In order to advance our knowledge on the complex interactions and competition among atmospheric dilution, dispersion and dynamics of UFPs, an aerosol dynamics-CFD coupled model is developed and validated against field measurements. A unique approach of applying periodic boundary conditions is proposed to model pollutant dispersion and dynamics in one unified domain from the tailpipe level to the ambient near-road environment. This approach significantly reduces the size of the computational domain, and therefore, allows fast simulation of multiple scenarios. The model is validated against measured turbulent kinetic energy (TKE) and pollution gradients near a major highway. Through a model sensitivity analysis, the relative importance of individual aerosol dynamical processes on the total particle number concentration (N) and particle number-size distribution (PSD) near a highway is investigated. The results demonstrate that (1) coagulation has a negligible effect on N and particle growth, (2) binary homogeneous nucleation (BHN) of H2SO4-H2O is likely responsible for elevated N closest to the road, (3) N and particle growth are very sensitive to the condensation of semi-volatile organics (SVOCs), particle dry deposition, and the interaction between these processes. The results also indicate that, without the proper treatment of atmospheric boundary layer (i.e. its wind profile and turbulence quantities), the nucleation rate would be underestimated by a factor of 5 in the vehicle wake region due to overestimated mixing. Therefore, introducing ABL conditions to activity-based emission models may potentially improve their performance in estimating UFP traffic emissions.

  12. Development towards a global operational aerosol consensus: basic climatological characteristics of the International Cooperative for Aerosol Prediction Multi-Model Ensemble (ICAP-MME)

    NASA Astrophysics Data System (ADS)

    Sessions, W. R.; Reid, J. S.; Benedetti, A.; Colarco, P. R.; da Silva, A.; Lu, S.; Sekiyama, T.; Tanaka, T. Y.; Baldasano, J. M.; Basart, S.; Brooks, M. E.; Eck, T. F.; Iredell, M.; Hansen, J. A.; Jorba, O. C.; Juang, H.-M. H.; Lynch, P.; Morcrette, J.-J.; Moorthi, S.; Mulcahy, J.; Pradhan, Y.; Razinger, M.; Sampson, C. B.; Wang, J.; Westphal, D. L.

    2014-06-01

    Over the past several years, there has been a rapid development in the number and quality of global aerosol models intended for operational forecasting use. Indeed, most centers with global numerical weather prediction (NWP) capabilities have some program for aerosol prediction. These aerosol models typically have differences in their underlying meteorology as well as aerosol sources, sinks, microphysics and transformations. However, like similar diversity in aerosol climate models, the aerosol forecast models have fairly similar overall bulk error statistics for aerosol optical thickness (AOT)-one of the few aerosol metrics that is globally available. Experience in climate and weather prediction has shown that in situations such as this where there are several independent models, a multi-model ensemble or consensus will be top performing in many key error metrics. Further, multi-model ensembles provide a highly valuable tool for forecasters attempting to predict severe aerosol events. Here we present the first steps in developing a global multi-model aerosol forecasting ensemble intended for eventual operational and basic research use. Drawing from members of the International Cooperative for Aerosol Prediction (ICAP) latest generation of quasi-operational aerosol models, five day AOT forecasts are analyzed for December 2011 through November 2012 from four institutions: ECMWF, JMA, NASA GSFC, and NRL/FNMOC. For dust, we also include the NOAA NGAC product in our analysis. The Barcelona Supercomputing Centre (NMMC) and UK Met office dust product have also recent become available with ICAP, but have insufficient data to be included in this analysis period. A simple consensus ensemble of member and mean AOT fields for modal species (e.g., fine and coarse mode, and a separate dust ensemble) is used to create the ICAP Multi-Model Ensemble (ICAP-MME). The ICAP-MME is run daily at 0Z for 6 hourly forecasts out to 120 h. Basing metrics on comparisons to 21 regionally

  13. Uncertainty associated with convective wet removal of entrained aerosols in a global climate model

    NASA Astrophysics Data System (ADS)

    Croft, B.; Pierce, J. R.; Martin, R. V.; Hoose, C.; Lohmann, U.

    2012-11-01

    The uncertainties associated with the wet removal of aerosols entrained above convective cloud bases are investigated in a global aerosol-climate model (ECHAM5-HAM) under a set of limiting assumptions for the wet removal of the entrained aerosols. The limiting assumptions for the wet removal of entrained aerosols are negligible scavenging and vigorous scavenging (either through activation, with size-dependent impaction scavenging, or with the prescribed fractions of the standard model). To facilitate this process-based study, an explicit representation of cloud-droplet-borne and ice-crystal-borne aerosol mass and number, for the purpose of wet removal, is introduced into the ECHAM5-HAM model. This replaces and is compared with the prescribed cloud-droplet-borne and ice-crystal-borne aerosol fraction scavenging scheme of the standard model. A 20% to 35% uncertainty in simulated global, annual mean aerosol mass burdens and optical depth (AOD) is attributed to different assumptions for the wet removal of aerosols entrained above convective cloud bases. Assumptions about the removal of aerosols entrained above convective cloud bases control modeled upper tropospheric aerosol concentrations by as much as one order of magnitude. Simulated aerosols entrained above convective cloud bases contribute 20% to 50% of modeled global, annual mean aerosol mass convective wet deposition (about 5% to 10% of the total dry and wet deposition), depending on the aerosol species, when including wet scavenging of those entrained aerosols (either by activation, size-dependent impaction, or with the prescribed fraction scheme). Among the simulations, the prescribed fraction and size-dependent impaction schemes yield the largest global, annual mean aerosol mass convective wet deposition (by about two-fold). However, the prescribed fraction scheme has more vigorous convective mixed-phase wet removal (by two to five-fold relative to the size-dependent impaction scheme) since nearly all

  14. Towards Improved MODIS Aerosol Retrieval over the US East Coast Region: Re-examining the Aerosol Model and Surface Assumptions

    NASA Technical Reports Server (NTRS)

    Levy, R. C.; Remer, L. A.; Kaufman, Y. J.; Holben, B. N.

    2002-01-01

    The MODerate resolution Imaging Spectrometer (MODIS) aboard the Terra and recently the Aqua platform, produces a set of aerosol products over both ocean and land regions. Previous validation efforts have shown that from a global perspective, aerosol optical depth (AOD) is successfully retrieved from MODIS. Even over coastal regions, the over- land and over-ocean retrievals are consistent with each other, and well matched with ground-based sunphotometer measurements (such as AERONET). However, the East Coast of the United States is one region where there is consistently a discrepancy between land and ocean retrievals. Over the ocean, MODIS AODs are consistent with coastal sunphotometer measurements, but over land, AODs are consistently over- estimated. In this study we use field data from the Chesapeake Lighthouse and Aircraft Measurements for Satellites experiment (CLAMS), (held during summer 2001) to determine the aerosol properties at a number of sites. Using the 6-S radiative transfer package, we compute simulated satellite radiances and compare them with observed MODIS radiances. We believe that the AOD over-estimation is not likely due to an incorrect choice of the urban/industrial aerosol models. Using 6-S to do an atmospheric correction for a very low AOD case, we show rather, that the discrepancies are likely a result of incorrect assumptions about the surface reflectance properties. Understanding and improving MODIS retrievals over the East Coast will not only improve the global quality of MODIS, but also would enable the use of MODIS as a tool for monitoring regional aerosol events.

  15. Evolution of ozone, particulates, and aerosol direct radiative forcing in the vicinity of Houston using a fully coupled meteorology-chemistry-aerosol model

    NASA Astrophysics Data System (ADS)

    Fast, Jerome D.; Gustafson, William I.; Easter, Richard C.; Zaveri, Rahul A.; Barnard, James C.; Chapman, Elaine G.; Grell, Georg A.; Peckham, Steven E.

    2006-11-01

    A new fully coupled meteorology-chemistry-aerosol model is used to simulate the urban- to regional-scale variations in trace gases, particulates, and aerosol direct radiative forcing in the vicinity of Houston over a 5 day summer period. Model performance is evaluated using a wide range of meteorological, chemistry, and particulate measurements obtained during the 2000 Texas Air Quality Study. The predicted trace gas and particulate distributions were qualitatively similar to the surface and aircraft measurements with considerable spatial variations resulting from urban, power plant, and industrial sources of primary pollutants. Sulfate, organic carbon, and other inorganics were the largest constituents of the predicted particulates. The predicted shortwave radiation was 30 to 40 W m-2 closer to the observations when the aerosol optical properties were incorporated into the shortwave radiation scheme; however, the predicted hourly aerosol radiative forcing was still underestimated by 10 to 50 W m-2. The predicted aerosol radiative forcing was larger over Houston and the industrial ship channel than over the rural areas, consistent with surface measurements. The differences between the observed and simulated aerosol radiative forcing resulted from transport errors, relative humidity errors in the upper convective boundary layer that affect aerosol water content, secondary organic aerosols that were not yet included in the model, and uncertainties in the primary particulate emission rates. The current model was run in a predictive mode and demonstrates the challenges of accurately simulating all of the meteorological, chemical, and aerosol parameters over urban to regional scales that can affect aerosol radiative forcing.

  16. Characteristics-based sectional modeling of aerosol nucleation and condensation

    NASA Astrophysics Data System (ADS)

    Frederix, E. M. A.; Stanic, M.; Kuczaj, A. K.; Nordlund, M.; Geurts, B. J.

    2016-12-01

    A new numerical method for the solution of an internally mixed spatially homogeneous sectional model for aerosol nucleation and condensation is proposed. The characteristics method is used to predict droplet sizes within a discrete time step. The method is designed such that 1) a pre-specified number of moments of the droplet size distribution may be preserved, 2) there exists no time step stability restriction related to the condensation rate and section size, 3) highly skewed fixed sectional distributions may be used and 4) it is straightforward to extend to spatially inhomogeneous settings and to incorporate droplet coagulation and break-up. We derive, starting from mass conservation, a consistent internally mixed multi-species aerosol model. For certain condensational growth laws analytical solutions exist, against which the method is validated. Using two-moment and four-moment-preserving schemes, we find first order convergence of the numerical solution to the analytical result, as a function of the number of sections. As the four-moment-preserving scheme does not guarantee positivity of the solution, a hybrid scheme is proposed, which, when needed, locally reverts back to two-moment preservation, to prevent negativity. As an illustration, the method is applied to a complete multi-species homogeneous nucleation and condensation problem.

  17. Atmospheric aerosols in Rome, Italy: sources, dynamics and spatial variations during two seasons

    NASA Astrophysics Data System (ADS)

    Struckmeier, Caroline; Drewnick, Frank; Fachinger, Friederike; Gobbi, Gian Paolo; Borrmann, Stephan

    2016-12-01

    every day at the urban location, at the suburban location they were only found under favourable meteorological conditions, but were independent of advection of the Rome emission plume. Particles from sources in the metropolitan area of Rome and particles advected from outside Rome contributed 42-70 and 30-58 % to the total measured PM1, respectively. Apart from the general aerosol characteristics, in this study the properties (e.g. emission strength) and dynamics (e.g. temporal behaviour) of each identified aerosol type is investigated in detail to provide a better understanding of the observed seasonal and spatial differences.

  18. GASFLOW: A Computational Fluid Dynamics Code for Gases, Aerosols, and Combustion, Volume 3: Assessment Manual

    SciTech Connect

    Müller, C.; Hughes, E. D.; Niederauer, G. F.; Wilkening, H.; Travis, J. R.; Spore, J. W.; Royl, P.; Baumann, W.

    1998-10-01

    Los Alamos National Laboratory (LANL) and Forschungszentrum Karlsruhe (FzK) are developing GASFLOW, a three-dimensional (3D) fluid dynamics field code as a best- estimate tool to characterize local phenomena within a flow field. Examples of 3D phenomena include circulation patterns; flow stratification; hydrogen distribution mixing and stratification; combustion and flame propagation; effects of noncondensable gas distribution on local condensation and evaporation; and aerosol entrainment, transport, and deposition. An analysis with GASFLOW will result in a prediction of the gas composition and discrete particle distribution in space and time throughout the facility and the resulting pressure and temperature loadings on the walls and internal structures with or without combustion. A major application of GASFLOW is for predicting the transport, mixing, and combustion of hydrogen and other gases in nuclear reactor containment and other facilities. It has been applied to situations involving transporting and distributing combustible gas mixtures. It has been used to study gas dynamic behavior in low-speed, buoyancy-driven flows, as well as sonic flows or diffusion dominated flows; and during chemically reacting flows, including deflagrations. The effects of controlling such mixtures by safety systems can be analyzed. The code version described in this manual is designated GASFLOW 2.1, which combines previous versions of the United States Nuclear Regulatory Commission code HMS (for Hydrogen Mixing Studies) and the Department of Energy and FzK versions of GASFLOW. The code was written in standard Fortran 90. This manual comprises three volumes. Volume I describes the governing physical equations and computational model. Volume II describes how to use the code to set up a model geometry, specify gas species and material properties, define initial and boundary conditions, and specify different outputs, especially graphical displays. Sample problems are included. Volume

  19. GASFLOW: A Computational Fluid Dynamics Code for Gases, Aerosols, and Combustion, Volume 2: User's Manual

    SciTech Connect

    Nichols, B. D.; Mueller, C.; Necker, G. A.; Travis, J. R.; Spore, J. W.; Lam, K. L.; Royl, P.; Wilson, T. L.

    1998-10-01

    Los Alamos National Laboratory (LANL) and Forschungszentrum Karlsruhe (FzK) are developing GASFLOW, a three-dimensional (3D) fluid dynamics field code as a best-estimate tool to characterize local phenomena within a flow field. Examples of 3D phenomena include circulation patterns; flow stratification; hydrogen distribution mixing and stratification; combustion and flame propagation; effects of noncondensable gas distribution on local condensation and evaporation; and aerosol entrainment, transport, and deposition. An analysis with GASFLOW will result in a prediction of the gas composition and discrete particle distribution in space and time throughout the facility and the resulting pressure and temperature loadings on the walls and internal structures with or without combustion. A major application of GASFLOW is for predicting the transport, mixing, and combustion of hydrogen and other gases in nuclear reactor containment and other facilities. It has been applied to situations involving transporting and distributing combustible gas mixtures. It has been used to study gas dynamic behavior in low-speed, buoyancy-driven flows, as well as sonic flows or diffusion dominated flows; and during chemically reacting flows, including deflagrations. The effects of controlling such mixtures by safety systems can be analyzed. The code version described in this manual is designated GASFLOW 2.1, which combines previous versions of the United States Nuclear Regulatory Commission code HMS (for Hydrogen Mixing Studies) and the Department of Energy and FzK versions of GASFLOW. The code was written in standard Fortran 90. This manual comprises three volumes. Volume I describes the governing physical equations and computational model. Volume II describes how to use the code to set up a model geometry, specify gas species and material properties, define initial and boundary conditions, and specify different outputs, especially graphical displays. Sample problems are included. Volume III

  20. Maritime Aerosol Network as a Component of AERONET - First Results and Comparison with Global Aerosol Models and Satellite Retrievals

    NASA Technical Reports Server (NTRS)

    Smirnov, A.; Holben, B. N.; Giles, D. M.; Slutsker, I.; O'Neill, N. T.; Eck, T. F.; Macke, A.; Croot, P.; Courcoux, Y.; Sakerin, S. M.; Smyth, T. J.; Zielinski, T.; Zibordi, G.; Goes, J. I.; Harvey, M. J.; Quinn, P. K.; Nelson, N. B.; Radionov, V. F.; Duarte, C. M.; Remer, L. A.; Kahn, R. A.; Kleidman, R. G.; Gaitley, B. J.; Tan, Q.; Diehl, T. L.

    2011-01-01

    The Maritime Aerosol Network (MAN) has been collecting data over the oceans since November 2006. Over 80 cruises were completed through early 2010 with deployments continuing. Measurement areas included various parts of the Atlantic Ocean, the Northern and Southern Pacific Ocean, the South Indian Ocean, the Southern Ocean, the Arctic Ocean and inland seas. MAN deploys Microtops handheld sunphotometers and utilizes a calibration procedure and data processing traceable to AERONET. Data collection included areas that previously had no aerosol optical depth (AOD) coverage at all, particularly vast areas of the Southern Ocean. The MAN data archive provides a valuable resource for aerosol studies in maritime environments. In the current paper we present results of AOD measurements over the oceans, and make a comparison with satellite AOD retrievals and model simulations.

  1. Future aerosol emissions: a multi-model comparison

    SciTech Connect

    Smith, Steven J.; Rao, Shilpa; Riahi, Keywan; van Vuuren, Detlef P.; Calvin, Katherine V.; Kyle, Page

    2016-08-02

    This paper compares projections over the 21st century of SO2, BC, and OC emissions from three technologically detailed, long-term integrated assessment models. The character of the projections and the response of emissions due to a comprehensive climate policy are discussed. In a continuation of historical experience, aerosol and precursor emissions are increasingly decoupled from carbon dioxide emissions over the 21st century. Implementation of a comprehensive climate policy further reduces emissions, although there is significant variation in this response by sector and by model. Differences in model responses can be traced to specific characteristics of reference case end-use and supply-side technology deployment and emissions control assumptions, which are detailed by sector.

  2. Complex Coupling of Air Quality and Climate-Relevant Aerosols in a Chemistry-Aerosol Microphysics Model

    NASA Astrophysics Data System (ADS)

    Yoshioka, M.; Carslaw, K. S.; Reddington, C.; Mann, G.

    2013-12-01

    Controlling emissions of aerosols and their precursors to improve air quality will impact the climate through direct and indirect radiative forcing. We have investigated the impacts of changes in a range of aerosol and gas-phase emission fluxes and changes in temperature on air quality and climate change metrics using a global aerosol microphysics and chemistry model, GLOMAP. We investigate how the responses of PM2.5 and cloud condensation nuclei (CCN) are coupled, and how attempts to improve air quality could have inadvertent effects on CCN, clouds and climate. The parameter perturbations considered are a 5°C increase in global temperature, increased or decreased precursor emissions of anthropogenic SO2, NH3, and NOx, and biogenic monoterpenes, and increased or decreased primary emissions of organic and black carbon aerosols from wildfire, fossil fuel, and biofuel. To quantify the interactions, we define a new sensitivity metric in terms of the response of CCN divided by the response of PM in different regions. .Our results show that the coupled chemistry and aerosol processes cause complex responses that will make any co-benefit policy decision problematic. In particular, we show that reducing SO2 emissions effectively reduces surface-level PM2.5 over continental regions in summer when background PM2.5 is high, with a relatively small reduction in marine CCN (and hence indirect radiative cooling over ocean), which is beneficial for near-term climate. Reducing NOx emissions does not improve summertime air quality very effectively but leads to a relatively high reduction of marine CCN. Reducing NH3 emissions has moderate effects on both PM2.5 and CCN. These three species are strongly coupled chemically and microphysically and the effects of changing emissions of one species on mass and size distributions of aerosols are very complex and spatially and temporally variable. For example, reducing SO2 emissions leads to reductions in sulphate and ammonium mass

  3. Aerosols and water vapor dynamics over the Kingdom of Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Farahat, Ashraf; El-Askary, Hesham; Al-Shaibani, Abdulaziz; Dogan, Umran

    2014-05-01

    The Kingdom of Saudi Arabia contains a vast desert area and the home of some of the largest deserts worldwide. This nature subjects the area to numerous dust storms. This is in addition to local emissions transported from industrial activities. The Arabian Peninsula dust storms have a major impact on air quality and affects dust cycle around the world. The nature of dust also affects air, ground traffics, and human health. Aerosols play a pivotal role in global climate change through their effects on the hydrological cycle and solar energy budget. Recently there have been some trials to study the nature of dust over the kingdom using satellite remote sensing and modeling to investigate the impact of aerosols of natural and anthropogenic origins from both local emissions and long-range transport on the air quality and atmospheric composition, yet a lot more needs to be done. In this study, data obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) on board of Terra and Aqua satellites are used to analyze aerosols properties over the thirteen provinces of the Kingdom of Saudi Arabia from April 2003 to January 2012. This analysis will help to characterize aerosol and cloud properties, and the seasonal hydrological factors to establish the relative contributions of aerosols derived from different regions to the different Saudi provinces and their impacts on local atmospheric composition and air quality. During this period, we have examined possible nature and anthropogenic/natural aerosols/dust sources. The analysis is based on important parameters including the aerosol optical depth (AOD), fine mode fraction (FMF), cloud properties including cloud top temperature (CTT), cloud top pressure (CTP) and the water vapor column. Correlation between water vapor and AOD was observed over three provinces which could be a result of pollution aerosols rather than dust and is, hence, acting as cloud condensation nuclei (CCN). Increasing anomalous aerosols pattern

  4. Aerosol simulation applying high resolution anthropogenic emissions with the EMAC chemistry-climate model

    NASA Astrophysics Data System (ADS)

    Pozzer, A.; de Meij, A.; Pringle, K. J.; Tost, H.; Doering, U. M.; van Aardenne, J.; Lelieveld, J.

    2011-09-01

    The new high resolution global anthropogenic emission inventory (EDGAR-CIRCE) of gas and aerosol pollutants has been incorporated in the chemistry general circulation model EMAC (ECHAM5/MESSy Atmospheric Chemistry). A high horizontal resolution simulation is performed for the years 2005-2008 to evaluate the capability of the model and the emissions to reproduce observed aerosol concentrations and aerosol optical depth (AOD) values. Model output is compared with observations from different measurement networks (CASTNET, EMEP and EANET) and AODs from remote sensing instruments (MODIS and MISR). The model reproduces the main spatial and temporal atmospheric features of the sulfate, ammonium and nitrate aerosol distributions. A good spatial agreement of the distribution of sulfate and ammonium aerosol is found when compared to observations, while calculated nitrate aerosol concentrations show some discrepancies. The simulated temporal development of the inorganic aerosols is in line with measurements of sulfate and nitrate aerosol, while for ammonium aerosol some deviations from observations occur over the USA. The calculated AODs agree well with the satellite observations in most regions, while a negative bias is found for the equatorial area and in the dust outflow regions (i.e. Central Atlantic and Northern Indian Ocean), due to an underestimation of biomass burning and aeolian dust emissions, respectively.

  5. A Pure Marine Aerosol Model, for Use in Remote Sensing Applications

    NASA Technical Reports Server (NTRS)

    Sayer, A. M.; Smirnov, A.; Hsu, N. C.; Holben, B. N.

    2011-01-01

    Retrievals of aerosol optical depth (AOD) and related parameters from satellite measurements typically involve prescribed models of aerosol size and composition, and are therefore dependent on how well these models are able to represent the radiative behaviour of real aerosols, This study uses aerosol volume size distributions retrieved from Sun-photometer measurements at 11 Aerosol Robotic Network (AERONET) island sites, spread throughout the world's oceans, as a basis to define such a model for unpolluted maritime aerosols. Size distributions are observed to be bimodal and approximately lognormal, although the coarse mode is skewed with a long tail on the low-radius end, The relationship of AOD and size distribution parameters to meteorological conditions is also examined, As wind speed increases, so do coarse-mode volume and radius, The AOD and Angstrom exponent (alpha) show linear relationships with wind speed, although there is considerable scatter in all these relationships, limiting their predictive power. Links between aerosol properties and near-surface relative humidity, columnar water vapor, and sea surface temperature are also explored. A recommended bimodal maritime model, which is able to reconstruct the AERONET AOD with accuracy of order 0.01-0.02, is presented for use in aerosol remote sensing applications. This accuracy holds at most sites and for wavelengths between 340 nm and 1020 nm. Calculated lidar ratios are also provided, and differ significantly from those currently used in Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) processing.

  6. Global aerosol modeling with the online NMMB/BSC Chemical Transport Model: sensitivity to fire injection height prescription and secondary organic aerosol schemes

    NASA Astrophysics Data System (ADS)

    Spada, Michele; Jorba, Oriol; Pérez García-Pando, Carlos; Tsigaridis, Kostas; Soares, Joana; Obiso, Vincenzo; Janjic, Zavisa; Baldasano, Jose M.

    2015-04-01

    We develop and evaluate a fully online-coupled model simulating the life-cycle of the most relevant global aerosols (i.e. mineral dust, sea-salt, black carbon, primary and secondary organic aerosols, and sulfate) and their feedbacks upon atmospheric chemistry and radiative balance. Following the capabilities of its meteorological core, the model has been designed to simulate both global and regional scales with unvaried parameterizations: this allows detailed investigation on the aerosol processes bridging the gap between global and regional models. Since the strong uncertainties affecting aerosol models are often unresponsive to model complexity, we choose to introduce complexity only when it clearly improves results and leads to a better understanding of the simulated aerosol processes. We test two important sources of uncertainty - the fires injection height and secondary organic aerosol (SOA) production - by comparing a baseline simulation with experiments using more advanced approaches. First, injection heights prescribed by Dentener et al. (2006, ACP) are compared with climatological injection heights derived from satellite measurements and produced through the Integrated Monitoring and Modeling System For Wildland Fires (IS4FIRES). Also global patterns of SOA produced by the yield conversion of terpenes as prescribed by Dentener et al. (2006, ACP) are compared with those simulated by the two-product approach of Tsigaridis et al. (2003, ACP). We evaluate our simulations using a variety of observations and measurement techniques. Additionally, we discuss our results in comparison to other global models within AEROCOM and ACCMIP.

  7. Model analysis of influences of aerosol mixing state upon its optical properties in East Asia

    NASA Astrophysics Data System (ADS)

    Han, Xiao; Zhang, Meigen; Zhu, Lingyun; Xu, Liren

    2013-07-01

    The air quality model system RAMS (Regional Atmospheric Modeling System)-CMAQ (Models-3 Community Multi-scale Air Quality) coupled with an aerosol optical/radiative module was applied to investigate the impact of different aerosol mixing states (i.e., externally mixed, half externally and half internally mixed, and internally mixed) on radiative forcing in East Asia. The simulation results show that the aerosol optical depth (AOD) generally increased when the aerosol mixing state changed from externally mixed to internally mixed, while the single scattering albedo (SSA) decreased. Therefore, the scattering and absorption properties of aerosols can be significantly affected by the change of aerosol mixing states. Comparison of simulated and observed SSAs at five AERONET (Aerosol Robotic Network) sites suggests that SSA could be better estimated by considering aerosol particles to be internally mixed. Model analysis indicates that the impact of aerosol mixing state upon aerosol direct radiative forcing (DRF) is complex. Generally, the cooling effect of aerosols over East Asia are enhanced in the northern part of East Asia (Northern China, Korean peninsula, and the surrounding area of Japan) and are reduced in the southern part of East Asia (Sichuan Basin and Southeast China) by internal mixing process, and the variation range can reach ±5 W m-2. The analysis shows that the internal mixing between inorganic salt and dust is likely the main reason that the cooling effect strengthens. Conversely, the internal mixture of anthropogenic aerosols, including sulfate, nitrate, ammonium, black carbon, and organic carbon, could obviously weaken the cooling effect.

  8. Impacts of increasing the aerosol complexity in the Met Office global NWP model

    NASA Astrophysics Data System (ADS)

    Mulcahy, Jane; Walters, David; Bellouin, Nicolas; Milton, Sean

    2014-05-01

    Inclusion of the direct and indirect radiative effects of aerosols in high resolution global numerical weather prediction (NWP) models is being increasingly recognised as important for the improved accuracy of short-range weather forecasts. In this study the impacts of increasing the aerosol complexity in the global NWP configuration of the Met Office Unified Model (MetUM) are investigated. A hierarchy of aerosol representations are evaluated including three dimensional monthly mean speciated aerosol climatologies, fully prognostic aerosols modelled using the CLASSIC aerosol scheme and finally, initialised aerosols using assimilated aerosol fields from the GEMS project. The prognostic aerosol schemes are better able to predict the temporal and spatial variation of atmospheric aerosol optical depth, which is particularly important in cases of large sporadic aerosol events such as large dust storms or forest fires. Including the direct effect of aerosols improves model biases in outgoing longwave radiation over West Africa due to a better representation of dust. Inclusion of the indirect aerosol effects has significant impacts on the SW radiation particularly at high latitudes due to lower cloud amounts in high latitude clean air regions. This leads to improved surface radiation biases at the North Slope of Alaska ARM site. Verification of temperature and height forecasts is also improved in this region. Impacts on the global mean model precipitation and large-scale circulation fields were found to be generally small in the short range forecasts. However, the indirect aerosol effect leads to a strengthening of the low level monsoon flow over the Arabian Sea and Bay of Bengal and an increase in precipitation over Southeast Asia. This study highlights the importance of including a more realistic treatment of aerosol-cloud interactions in global NWP models and the potential for improved global environmental prediction systems through the incorporation of more complex

  9. The DACCIWA Project: Dynamics-Aerosol-Chemistry-Cloud interactions in West Africa

    NASA Astrophysics Data System (ADS)

    Knippertz, Peter

    2014-05-01

    Massive economic and population growth and urbanisation are expected to lead to a tripling of anthropogenic emissions from southern West Africa (SWA) between 2000 and 2030, the impacts of which on human health, ecosystems, food security and the regional climate are largely unknown. An assessment of these impacts is complicated by (a) a superposition with effects of global climate change, (b) the strong dependence of SWA on the sensitive West African monsoon, (c) incomplete scientific understanding of interactions between emissions, clouds, radiation, precipitation and regional circulations and (d) by a lack of observations to advance our understanding and improve predictions. The purpose of this contribution is to introduce the research consortium DACCIWA (Dynamics-Aerosol-Chemistry-Cloud interactions in West Africa), which comprises 16 partners in six European and West African countries. The interdisciplinary DACCIWA team will build on the scientific and logistical foundations established by the African Monsoon Multidisciplinary Analysis (AMMA) project and collaborate closely with operational centres. DACCIWA will receive funding of about M8.75€ from the European Commission as part of Framework Programme 7 from 2015 until 2018. The DACCIWA project will conduct extensive fieldwork in SWA to collect high-quality observations, spanning the entire process chain from surface-based natural and anthropogenic emissions to impacts on health, ecosystems and climate. This will include a major field campaign in summer 2015 with three research aircrafts and two ground-based supersites. Combining the resulting benchmark dataset with a wide range of modelling activities will allow us: (a) to assess all relevant physical and chemical processes, (b) to improve the monitoring of climate and compositional parameters from space, (c) to determine health impacts from air pollution, and (d) to develop the next generation of weather and climate models capable of representing coupled

  10. Representation and evaluation of aerosol mixing state in a climate model

    NASA Astrophysics Data System (ADS)

    Bauer, S. E.; Prather, K. A.; Ault, A. P.

    2011-12-01

    Aerosol particles in the atmosphere are composed out of multiple chemical species. The aerosol mixing state is an important aerosol property that will determine the interaction of aerosols with the climate system via radiative forcings and cloud activation. Through the introduction of aerosol microphysics into climate models, aerosol mixing state is by now taken into account to a certain extend in climate models, and evaluation of mixing state is the next challenge. Here we use data from the Aerosol Time of Flight Mass Spectrometer (ATOFMS) and compare the results to the GISS-modelE-MATRIX model, a global climate model including a detailed aerosol micro-physical scheme. We use data from various field campaigns probing, urban, rural and maritime air masses and compare those to climatological and nudged simulations for the years 2005 to 2009. ATOFMS provides information about the size distributions of several mixing state classes, including the chemical components of black and organic carbon, sulfates, dust and salts. MATRIX simulates 16 aerosol populations, which definitions are based on mixing state. We have grouped ATOFMS and MATRIX data into similar mixing state classes and compare the size resolved number concentrations against each other. As a first result we find that climatological simulations are rather difficult to evaluate with field data, and that nudged simulations give a much better agreement. However this is not just caused by the better fit of natural - meteorological driven - aerosol components, but also due to the interaction between meteorology and aerosol formation. The model seems to get the right amount of mixing state of black carbon material with sulfate and organic components, but seems to always overestimate the fraction of black carbon that is externally mixed. In order to understand this bias between model and the ATOFMS data, we will look into microphysical processes near emission sources and investigate the climate relevance of these sub

  11. Dynamic causal modelling revisited.

    PubMed

    Friston, K J; Preller, Katrin H; Mathys, Chris; Cagnan, Hayriye; Heinzle, Jakob; Razi, Adeel; Zeidman, Peter

    2017-02-17

    This paper revisits the dynamic causal modelling of fMRI timeseries by replacing the usual (Taylor) approximation to neuronal dynamics with a neural mass model of the canonical microcircuit. This provides a generative or dynamic causal model of laminar specific responses that can generate haemodynamic and electrophysiological measurements. In principle, this allows the fusion of haemodynamic and (event related or induced) electrophysiological responses. Furthermore, it enables Bayesian model comparison of competing hypotheses about physiologically plausible synaptic effects; for example, does attentional modulation act on superficial or deep pyramidal cells - or both? In this technical note, we describe the resulting dynamic causal model and provide an illustrative application to the attention to visual motion dataset used in previous papers. Our focus here is on how to answer long-standing questions in fMRI; for example, do haemodynamic responses reflect extrinsic (afferent) input from distant cortical regions, or do they reflect intrinsic (recurrent) neuronal activity? To what extent do inhibitory interneurons contribute to neurovascular coupling? What is the relationship between haemodynamic responses and the frequency of induced neuronal activity? This paper does not pretend to answer these questions; rather it shows how they can be addressed using neural mass models of fMRI timeseries.

  12. Integration of prognostic aerosol-cloud interactions in a chemistry transport model coupled offline to a regional climate model

    NASA Astrophysics Data System (ADS)

    Thomas, M. A.; Kahnert, M.; Andersson, C.; Kokkola, H.; Hansson, U.; Jones, C.; Langner, J.; Devasthale, A.

    2015-06-01

    To reduce uncertainties and hence to obtain a better estimate of aerosol (direct and indirect) radiative forcing, next generation climate models aim for a tighter coupling between chemistry transport models and regional climate models and a better representation of aerosol-cloud interactions. In this study, this coupling is done by first forcing the Rossby Center regional climate model (RCA4) with ERA-Interim lateral boundaries and sea surface temperature (SST) using the standard cloud droplet number concentration (CDNC) formulation (hereafter, referred to as the "stand-alone RCA4 version" or "CTRL" simulation). In the stand-alone RCA4 version, CDNCs are constants distinguishing only between land and ocean surface. The meteorology from this simulation is then used to drive the chemistry transport model, Multiple-scale Atmospheric Transport and Chemistry (MATCH), which is coupled online with the aerosol dynamics model, Sectional Aerosol module for Large Scale Applications (SALSA). CDNC fields obtained from MATCH-SALSA are then fed back into a new RCA4 simulation. In this new simulation (referred to as "MOD" simulation), all parameters remain the same as in the first run except for the CDNCs provided by MATCH-SALSA. Simulations are carried out with this model setup for the period 2005-2012 over Europe, and the differences in cloud microphysical properties and radiative fluxes as a result of local CDNC changes and possible model responses are analysed. Our study shows substantial improvements in cloud microphysical properties with the input of the MATCH-SALSA derived 3-D CDNCs compared to the stand-alone RCA4 version. This model setup improves the spatial, seasonal and vertical distribution of CDNCs with a higher concentration observed over central Europe during boreal summer (JJA) and over eastern Europe and Russia during winter (DJF). Realistic cloud droplet radii (CD radii) values have been simulated with the maxima reaching 13 μm, whereas in the stand

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

    NASA Astrophysics Data System (ADS)

    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

  14. Toward a Minimal Representation of Aerosols in Climate Models: Comparative Decomposition of Aerosol Direct, Semidirect, and Indirect Radiative Forcing

    SciTech Connect

    Ghan, Steven J.; Liu, Xiaohong; Easter, Richard C.; Zaveri, Rahul A.; Rasch, Philip J.; Yoon, Jin-Ho; Eaton, Brian

    2012-10-01

    The authors have decomposed the anthropogenic aerosol radiative forcing into direct contributions from each aerosol species to the planetary energy balance through absorption and scattering of solar radiation, indirect effects of anthropogenic aerosol on solar and infrared radiation through droplet and crystal nucleation on aerosol, and semidirect effects through the influence of solar absorption on the distribution of clouds. A three-mode representation of the aerosol in version 5.1 of the Community Atmosphere Model (CAM5.1) yields global annual mean radiative forcing estimates for each of these forcing mechanisms that are within 0.1 W m–2 of estimates using a more complex seven-mode representation that distinguishes between fresh and aged black carbon and primary organic matter. Simulating fresh black carbon particles separately from internally mixed accumulation mode particles is found to be important only near fossil fuel sources. In addition to the usual large indirect effect on solar radiation, this study finds an unexpectedly large positive longwave indirect effect (because of enhanced cirrus produced by homogenous nucleation of ice crystals on anthropogenic sulfate), small shortwave and longwave semidirect effects, and a small direct effect (because of cancelation and interactions of direct effects of black carbon and sulfate). Differences between the threemode and seven-mode versions are significantly larger (up to 0.2 W m–2) when the hygroscopicity of primary organic matter is decreased from 0.1 to 0 and transfer of the primary carbonaceous aerosol to the accumulation mode in the seven-mode version requires more hygroscopic material coating the primary particles. Radiative forcing by cloudborne anthropogenic black carbon is only 20.07 W m–2.

  15. Modeling aerosol water uptake in the arctic based on the κ-Kohler theory

    NASA Astrophysics Data System (ADS)

    Rastak, N.; Ekman, A.; Silvergren, S.; Zieger, P.; Wideqvist, U.; Ström, J.; Svenningsson, B.; Tunved, P.; Riipinen, I.

    2013-05-01

    Water uptake or hygroscopicity is one of the most fundamental properties of atmospheric aerosols. Aerosol particles containing soluble materials can grow in size by absorbing water in ambient atmosphere. This property is measured by a parameter known as growth factor (GF), which is defined as the ratio of the wet diameter to the dry diameter. Hygroscopicity controls the size of an aerosol particle and therefore its optical properties in the atmosphere. Hygroscopic growth depends on the dry size of the particle, its chemical composition and the relative humidity in the ambient air (Fitzgerald, 1975; Pilinis et al., 1995). One of the typical problems in aerosol studies is the lack of measurements of aerosol size distributions and optical properties in ambient conditions. The gap between dry measurements and the real humid atmosphere is filled in this study by utilizing a hygroscopic model which calculates the hygroscopic growth of aerosol particles at Mt Zeppelin station, Ny Ålesund, Svalbard during 2008.

  16. Estimation of biomass burning influence on air pollution around Beijing from an aerosol retrieval model.

    PubMed

    Mukai, Sonoyo; Yasumoto, Masayoshi; Nakata, Makiko

    2014-01-01

    We investigate heavy haze episodes (with dense concentrations of atmospheric aerosols) occurring around Beijing in June, when serious air pollution was detected by both satellite and ground measurements. Aerosol retrieval is achieved by radiative transfer simulation in an Earth atmosphere model. We solve the radiative transfer problem in the case of haze episodes by successive order of scattering. We conclude that air pollution around Beijing in June is mainly due to increased emissions of anthropogenic aerosols and that carbonaceous aerosols from agriculture biomass burning in Southeast Asia also contribute to pollution.

  17. Assessing the effects of anthropogenic aerosols on Pacific storm track using a multiscale global climate model.

    PubMed

    Wang, Yuan; Wang, Minghuai; Zhang, Renyi; Ghan, Steven J; Lin, Yun; Hu, Jiaxi; Pan, Bowen; Levy, Misti; Jiang, Jonathan H; Molina, Mario J

    2014-05-13

    Atmospheric aerosols affect weather and global general circulation by modifying cloud and precipitation processes, but the magnitude of cloud adjustment by aerosols remains poorly quantified and represents the largest uncertainty in estimated forcing of climate change. Here we assess the effects of anthropogenic aerosols on the Pacific storm track, using a multiscale global aerosol-climate model (GCM). Simulations of two aerosol scenarios corresponding to the present day and preindustrial conditions reveal long-range transport of anthropogenic aerosols across the north Pacific and large resulting changes in the aerosol optical depth, cloud droplet number concentration, and cloud and ice water paths. Shortwave and longwave cloud radiative forcing at the top of atmosphere are changed by -2.5 and +1.3 W m(-2), respectively, by emission changes from preindustrial to present day, and an increased cloud top height indicates invigorated midlatitude cyclones. The overall increased precipitation and poleward heat transport reflect intensification of the Pacific storm track by anthropogenic aerosols. Hence, this work provides, for the first time to the authors' knowledge, a global perspective of the effects of Asian pollution outflows from GCMs. Furthermore, our results suggest that the multiscale modeling framework is essential in producing the aerosol invigoration effect of deep convective clouds on a global scale.

  18. Assessing the Effects of Anthropogenic Aerosols on Pacific Storm Track Using a Multiscale Global Climate Model

    SciTech Connect

    Wang, Yuan; Wang, Minghuai; Zhang, Renyi; Ghan, Steven J.; Lin, Yun; Hu, Jiaxi; Pan, Bowen; Levy, Misti; Jiang, Jonathan; Molina, Mario J.

    2014-05-13

    Atmospheric aerosols impact weather and global general circulation by modifying cloud and precipitation processes, but the magnitude of cloud adjustment by aerosols remains poorly quantified and represents the largest uncertainty in estimated forcing of climate change. Here we assess the impacts of anthropogenic aerosols on the Pacific storm track using a multi-scale global aerosol-climate model (GCM). Simulations of two aerosol scenarios corresponding to the present day and pre-industrial conditions reveal long-range transport of anthropogenic aerosols across the north Pacific and large resulting changes in the aerosol optical depth, cloud droplet number concentration, and cloud and ice water paths. Shortwave and longwave cloud radiative forcing at the top of atmosphere are changed by - 2.5 and + 1.3 W m-2, respectively, by emission changes from pre-industrial to present day, and an increased cloud-top height indicates invigorated mid-latitude cyclones. The overall increased precipitation and poleward heat transport reflect intensification of the Pacific storm track by anthropogenic aerosols. Hence, this work provides for the first time a global perspective of the impacts of Asian pollution outflows from GCMs. Furthermore, our results suggest that the multi-scale modeling framework is essential in producing the aerosol invigoration effect of deep convective clouds on the global scale.

  19. Assessment of aloft aerosol layers by ground-based lidar, satellite CALIPSO and model

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Cordero, L.; Nazmi, C.; Gross, B.; Moshary, F.; Ahmed, S. A.

    2013-12-01

    Aloft aerosol layers injected from dust storms and biomass burning are often transported over the long-distance, thus playing important roles in climate radiative forcing and air quality in the regional and continental scale. In particular, they are critical to satellite remote sensing of air quality, e.g. using satellite column aerosol optical depth (AOD) to evaluate surface PM2.5 concentration, because the aloft aerosol layer can make a substantial contribution to total AOD. These aloft aerosol plumes have been extensively observed or identified by the ground-lidar and space-borne lidar CALIOP/CALIPSO, as well as the global aerosol transport such as NRL-NAAPS. In this study, the aloft aerosol layers are investigated with a regional NOAA-CREST Lidar Network (CLN) in the East Coast of U.S., spaceborne lidar CAIPSO observations and NAAPS model forecast. We first analyze the height distribution and seasonal occurrence of aloft aerosol plumes from the multi-year CLN-lidar dataset. We also explore specific aloft aerosol layers and type classifications between NAAPS-model and CLN-lidar observations to asses NAAPS with special attention to time slices when MODIS AOD assimilation is present or not. Moreover, we assess the potential of NAAPS to identify and separate between aloft aerosol layers ('unclear' sky) and the non-aloft-layer ('clear' sky). This identification is very important in filtering the use of satellite AOD retrievals in potential PM2.5 estimators.

  20. Aerosol transport simulations in indoor and outdoor environments using computational fluid dynamics (CFD)

    NASA Astrophysics Data System (ADS)

    Landazuri, Andrea C.

    This dissertation focuses on aerosol transport modeling in occupational environments and mining sites in Arizona using computational fluid dynamics (CFD). The impacts of human exposure in both environments are explored with the emphasis on turbulence, wind speed, wind direction and particle sizes. Final emissions simulations involved the digitalization process of available elevation contour plots of one of the mining sites to account for realistic topographical features. The digital elevation map (DEM) of one of the sites was imported to COMSOL MULTIPHYSICSRTM for subsequent turbulence and particle simulations. Simulation results that include realistic topography show considerable deviations of wind direction. Inter-element correlation results using metal and metalloid size resolved concentration data using a Micro-Orifice Uniform Deposit Impactor (MOUDI) under given wind speeds and directions provided guidance on groups of metals that coexist throughout mining activities. Groups between Fe-Mg, Cr-Fe, Al-Sc, Sc-Fe, and Mg-Al are strongly correlated for unrestricted wind directions and speeds, suggesting that the source may be of soil origin (e.g. ore and tailings); also, groups of elements where Cu is present, in the coarse fraction range, may come from mechanical action mining activities and saltation phenomenon. Besides, MOUDI data under low wind speeds (<2 m/s) and at night showed a strong correlation for 1 mum particles between the groups: Sc-Be-Mg, Cr-Al, Cu-Mn, Cd-Pb-Be, Cd-Cr, Cu-Pb, Pb-Cd, As-Cd-Pb. The As-Cd-Pb correlates strongly in almost all ranges of particle sizes. When restricted low wind speeds were imposed more groups of elements are evident and this may be justified with the fact that at lower speeds particles are more likely to settle. When linking these results with CFD simulations and Pb-isotope results it is concluded that the source of elements found in association with Pb in the fine fraction come from the ore that is subsequently processed

  1. Evaluating model parameterizations of submicron aerosol scattering and absorption with in situ data from ARCTAS 2008

    NASA Astrophysics Data System (ADS)

    Alvarado, Matthew J.; Lonsdale, Chantelle R.; Macintyre, Helen L.; Bian, Huisheng; Chin, Mian; Ridley, David A.; Heald, Colette L.; Thornhill, Kenneth L.; Anderson, Bruce E.; Cubison, Michael J.; Jimenez, Jose L.; Kondo, Yutaka; Sahu, Lokesh K.; Dibb, Jack E.; Wang, Chien

    2016-07-01

    Accurate modeling of the scattering and absorption of ultraviolet and visible radiation by aerosols is essential for accurate simulations of atmospheric chemistry and climate. Closure studies using in situ measurements of aerosol scattering and absorption can be used to evaluate and improve models of aerosol optical properties without interference from model errors in aerosol emissions, transport, chemistry, or deposition rates. Here we evaluate the ability of four externally mixed, fixed size distribution parameterizations used in global models to simulate submicron aerosol scattering and absorption at three wavelengths using in situ data gathered during the 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign. The four models are the NASA Global Modeling Initiative (GMI) Combo model, GEOS-Chem v9-02, the baseline configuration of a version of GEOS-Chem with online radiative transfer calculations (called GC-RT), and the Optical Properties of Aerosol and Clouds (OPAC v3.1) package. We also use the ARCTAS data to perform the first evaluation of the ability of the Aerosol Simulation Program (ASP v2.1) to simulate submicron aerosol scattering and absorption when in situ data on the aerosol size distribution are used, and examine the impact of different mixing rules for black carbon (BC) on the results. We find that the GMI model tends to overestimate submicron scattering and absorption at shorter wavelengths by 10-23 %, and that GMI has smaller absolute mean biases for submicron absorption than OPAC v3.1, GEOS-Chem v9-02, or GC-RT. However, the changes to the density and refractive index of BC in GC-RT improve the simulation of submicron aerosol absorption at all wavelengths relative to GEOS-Chem v9-02. Adding a variable size distribution, as in ASP v2.1, improves model performance for scattering but not for absorption, likely due to the assumption in ASP v2.1 that BC is present at a constant mass fraction

  2. Modeling of microphysics and optics of aerosol particles in the marine environments

    NASA Astrophysics Data System (ADS)

    Kaloshin, Gennady

    2013-05-01

    We present a microphysical model for the surface layer marine and coastal atmospheric aerosols that is based on long-term observations of size distributions for 0.01-100 μm particles. The fundamental feature of the model is a parameterization of amplitudes and widths for aerosol modes of the aerosol size distribution function (ASDF) as functions of fetch and wind speed. The shape of ASDF and its dependence on meteorological parameters, height above sea level (H), fetch (X), wind speed (U) and relative humidity (RH), are investigated. At present, the model covers the ranges H = 0 - 25 m, U = 3 - 18 km s-1, X ≤ 120 km and RH = 40 - 98%. The latest version of the Marine Aerosol Extinction Profiles model (MaexPro) is described and applied for the computation and analysis of the spectral profiles of aerosol extinction coefficients α(λ) in the wavelength band λ = 0.2-12 μm. MaexPro is based on the aforementioned aerosol model assuming spherically shaped aerosol particles and the well-known Mie theory. The spectral profiles of α(λ) calculated by MaexPro are in good agreement with observational data and the numerical results. Moreover, MaexPro was found to be an accurate and reliable tool for investigating the optical properties of atmospheric aerosols.

  3. Cloud/Aerosol Parameterizations: Application and Improvement of General Circulation Models

    SciTech Connect

    Penner, Joyce

    2012-06-30

    One of the biggest uncertainties associated with climate models and climate forcing is the treatment of aerosols and their effects on clouds. The effect of aerosols on clouds can be divided into two components: The first indirect effect is the forcing associated with increases in droplet concentrations; the second indirect effect is the forcing associated with changes in liquid water path, cloud morphology, and cloud lifetime. Both are highly uncertain. This project applied a cloud-resolving model to understand the response of clouds under a variety of conditions to changes in aerosols. These responses are categorized according to the large-scale meteorological conditions that lead to the response. Meteorological conditions were sampled from various fields, which, together with a global aerosol model determination of the change in aerosols from present day to pre-industrial conditions, was used to determine a first order estimate of the response of global cloud fields to changes in aerosols. The response of the clouds in the NCAR CAM3 GCM coupled to our global aerosol model were tested by examining whether the response is similar to that of the cloud resolving model and methods for improving the representation of clouds and cloud/aerosol interactions were examined.

  4. New Statistical Model for Variability of Aerosol Optical Thickness and its Application to Analysis of Global Satellite Datasets

    NASA Astrophysics Data System (ADS)

    Alexandrov, M. D.; Geogdzhayev, I. V.; Cairns, B.; Mishchenko, M. I.

    2013-05-01

    observations. The derived AOTVM parameters showed pronounced geographic and seasonal patterns associated with certain dominant aerosol types (such as dust, sea salt, biomass burning, and industrial pollution) and atmospheric dynamical processes (such as long-range transport and turbulence). The accuracy of differentiation between aerosol types based on AOTVM parameters can be evaluated by comparison with output of aerosol dynamical models and/or with retrievals of aerosol properties from spectral satellite measurements. On the other hand, the AOTVM dataset can be used for validation of AOT statistics in dynamical models.

  5. Modeling of solar radiation management: a comparison of simulations using reduced solar constant and stratospheric sulphate aerosols

    NASA Astrophysics Data System (ADS)

    Kalidindi, Sirisha; Bala, Govindasamy; Modak, Angshuman; Caldeira, Ken

    2015-05-01

    The climatic effects of Solar Radiation Management (SRM) geoengineering have been often modeled by simply reducing the solar constant. This is most likely valid only for space sunshades and not for atmosphere and surface based SRM methods. In this study, a global climate model is used to evaluate the differences in the climate response to SRM by uniform solar constant reduction and stratospheric aerosols. Our analysis shows that when global mean warming from a doubling of CO2 is nearly cancelled by both these methods, they are similar when important surface and tropospheric climate variables are considered. However, a difference of 1 K in the global mean stratospheric (61-9.8 hPa) temperature is simulated between the two SRM methods. Further, while the global mean surface diffuse radiation increases by ~23 % and direct radiation decreases by about 9 % in the case of sulphate aerosol SRM method, both direct and diffuse radiation decrease by similar fractional amounts (~1.0 %) when solar constant is reduced. When CO2 fertilization effects from elevated CO2 concentration levels are removed, the contribution from shaded leaves to gross primary productivity (GPP) increases by 1.8 % in aerosol SRM because of increased diffuse light. However, this increase is almost offset by a 15.2 % decline in sunlit contribution due to reduced direct light. Overall both the SRM simulations show similar decrease in GPP (~8 %) and net primary productivity (~3 %). Based on our results we conclude that the climate states produced by a reduction in solar constant and addition of aerosols into the stratosphere can be considered almost similar except for two important aspects: stratospheric temperature change and the consequent implications for the dynamics and the chemistry of the stratosphere and the partitioning of direct versus diffuse radiation reaching the surface. Further, the likely dependence of global hydrological cycle response on aerosol particle size and the latitudinal and

  6. Program Models A Laser Beam Focused In An Aerosol Spray

    NASA Technical Reports Server (NTRS)

    Barton, J. P.

    1996-01-01

    Monte Carlo analysis performed on packets of light. Program for Analysis of Laser Beam Focused Within Aerosol Spray (FLSPRY) developed for theoretical analysis of propagation of laser pulse optically focused within aerosol spray. Applied for example, to analyze laser ignition arrangement in which focused laser pulse used to ignite liquid aerosol fuel spray. Scattering and absorption of laser light by individual aerosol droplets evaluated by use of electromagnetic Lorenz-Mie theory. Written in FORTRAN 77 for both UNIX-based computers and DEC VAX-series computers. VAX version of program (LEW-16051). UNIX version (LEW-16065).

  7. A Global Aerosol Model Forecast for the ACE-Asia Field Experiment

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Ginoux, Paul; Lucchesi, Robert; Huebert, Barry; Weber, Rodney; Anderson, Tad; Masonis, Sarah; Blomquist, Byron; Bandy, Alan; Thornton, Donald

    2003-01-01

    We present the results of aerosol forecast during the Aerosol Characterization Experiment (ACE-Asia) field experiment in spring 2001, using the Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model and the meteorological forecast fields from the Goddard Earth Observing System Data Assimilation System (GEOS DAS). The aerosol model forecast provides direct information on aerosol optical thickness and concentrations, enabling effective flight planning, while feedbacks from measurements constantly evaluate the model, making successful model improvements. We verify the model forecast skill by comparing model predicted total aerosol extinction, dust, sulfate, and SO2 concentrations with those quantities measured by the C-130 aircraft during the ACE-Asia intensive operation period. The GEOS DAS meteorological forecast system shows excellent skills in predicting winds, relative humidity, and temperature for the ACE-Asia experiment area as well as for each individual flight, with skill scores usually above 0.7. The model is also skillful in forecast of pollution aerosols, with most scores above 0.5. The model correctly predicted the dust outbreak events and their trans-Pacific transport, but it constantly missed the high dust concentrations observed in the boundary layer. We attribute this missing dust source to the desertification regions in the Inner Mongolia Province in China, which have developed in recent years but were not included in the model during forecasting. After incorporating the desertification sources, the model is able to reproduce the observed high dust concentrations at low altitudes over the Yellow Sea. Two key elements for a successful aerosol model forecast are correct source locations that determine where the emissions take place, and realistic forecast winds and convection that determine where the aerosols are transported. We demonstrate that our global model can not only account for the large

  8. Modeling of secondary organic aerosols from mobile sources in Mexico City

    NASA Astrophysics Data System (ADS)

    Zavala, M.; Lei, W.; Bei, N.; Li, G.; Tsimpidi, A. P.; Karydis, V. A.; Pandis, S.; Molina, L. T.

    2009-04-01

    Mobile sources are significant contributors of emissions of CO, NOx, hydrocarbons and particle matter (PM) that constitute critical precursors of ozone as well as secondary organic and inorganic particles that decisively impact the photochemical levels and aerosol loadings in the atmosphere. Currently there are large uncertainties in regional air quality models during the treatment of aerosol formation from aerosol precursors via the production of condensable organic gases. As a result, the modeling of the concentrations and properties of aerosols resulted from mobile emissions sources is an important challenge. In this study we compare aerosol simulations using the PM-CAMx air quality model linked to the SAPRC99 chemical mechanism with measured aerosol data obtained during the MILAGRO/MCMA-2006 field campaign in Mexico City. The PM-CAMx modeling framework is based on the volatility-basis approach: both primary and secondary organic components are assumed to be photochemically reactive and are logarithmically distributed in volatility bins. The distinction of the volatility properties of aerosols precursors is particularly important for diesel and gasoline emission sources due to their different organic carbon speciation emissions profiles. Using this volatility-basis technique, we will present results on the relative contributions from both gasoline and diesel vehicle fleet emission sources to the formation of secondary organic aerosols in an urban area.

  9. AEROSOL INORGANICS AND ORGANICS MODEL (AIOM) WITH USER DEFINED PROPERTIES FOR ORGANIC COMPOUNDS

    EPA Science Inventory

    The Aerosol Inorganics Model (AIM) is widely used to calculate gas/liquid/solid phase equilibrium in aerosol systems containing the species H+-NH4+-SO42--NO3--H2O over a range of tropospheric ...

  10. Aerosol Properties and Processes: A Path from Field and Laboratory Measurements to Global Climate Models

    SciTech Connect

    Ghan, Steven J.; Schwartz, Stephen E.

    2007-07-01

    Aerosols exert a substantial influence on climate and climate change through a variety of complex mechanisms. Consequently there is a need to represent aerosol effects in global climate models, and models have begun to include representations of these effects. However, the treatment of aerosols in current global climate models is presently highly simplified, omitting many important processes and feedbacks. Consequently there is need for substantial improvement. Here we describe the U. S. Department of Energy strategy for improving the treatment of aerosol properties and processes in global climate models. The strategy begins with a foundation of field and laboratory measurements that provide the basis for modules of selected aerosol properties and processes. These modules are then integrated in regional aerosol models, which are evaluated by comparing with field measurements. Issues of scale are then addressed so that the modules can be applied to global aerosol models, which are evaluated by comparing with global satellite measurements. Finally, the validated set of modules are applied to global climate models for multi-century simulations. This strategy can be applied to successive generations of global climate models.

  11. Impact of Asian Aerosols on Precipitation Over California: An Observational and Model Based Approach

    NASA Technical Reports Server (NTRS)

    Naeger, Aaron R.; Molthan, Andrew L.; Zavodsky, Bradley T.; Creamean, Jessie M.

    2015-01-01

    Dust and pollution emissions from Asia are often transported across the Pacific Ocean to over the western United States. Therefore, it is essential to fully understand the impact of these aerosols on clouds and precipitation forming over the eastern Pacific and western United States, especially during atmospheric river events that account for up to half of California's annual precipitation and can lead to widespread flooding. In order for numerical modeling simulations to accurately represent the present and future regional climate of the western United States, we must account for the aerosol-cloud-precipitation interactions associated with Asian dust and pollution aerosols. Therefore, we have constructed a detailed study utilizing multi-sensor satellite observations, NOAA-led field campaign measurements, and targeted numerical modeling studies where Asian aerosols interacted with cloud and precipitation processes over the western United States. In particular, we utilize aerosol optical depth retrievals from the NASA Moderate Resolution Imaging Spectroradiometer (MODIS), NOAA Geostationary Operational Environmental Satellite (GOES-11), and Japan Meteorological Agency (JMA) Multi-functional Transport Satellite (MTSAT) to effectively detect and monitor the trans-Pacific transport of Asian dust and pollution. The aerosol optical depth (AOD) retrievals are used in assimilating the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) in order to provide the model with an accurate representation of the aerosol spatial distribution across the Pacific. We conduct WRF-Chem model simulations of several cold-season atmospheric river events that interacted with Asian aerosols and brought significant precipitation over California during February-March 2011 when the NOAA CalWater field campaign was ongoing. The CalWater field campaign consisted of aircraft and surface measurements of aerosol and precipitation processes that help extensively validate our WRF

  12. Intercomparison of Models Representing Direct Shortwave Radiative Forcing by Sulfate Aerosols

    NASA Technical Reports Server (NTRS)

    Boucher, O.; Schwartz, S. E.; Ackerman, T. P.; Anderson, T. L.; Bergstrom, B.; Bonnel, B.; Dahlback, A.; Fouquart, Y.; Chylek, P.; Fu, Q.; Halthore, R. N.; Haywood, J. M.; Iversen, T.; Kato, S.; Kinne, S.; Kirkevag, A.; Knapp, K. R.; Lacis, A.; Laszlo, I.; Mishchenko, M. I.

    2000-01-01

    The importance of aerosols as agents of climate change has recently been highlighted. However, the magnitude of aerosol forcing by scattering of shortwave radiation (direct forcing) is still very uncertain even for the relatively well characterized sulfate aerosol. A potential source of uncertainty is in the model representation of aerosol optical properties and aerosol influences on radiative transfer in the atmosphere. Although radiative transfer methods and codes have been compared in the past, these comparisons have not focused on aerosol forcing (change in net radiative flux at the top of the atmosphere). Here we report results of a project involving 12 groups using 15 models to examine radiative forcing by sulfate aerosol for a wide range of values of particle radius, aerosol optical depth, surface albedo, and solar zenith angle. Among the models that were employed were high and low spectral resolution models incorporating a variety of radiative transfer approximations as well as a line-by-line model. The normalized forcings (forcing per sulfate column burden) obtained with the several radiative transfer models were examined, and the discrepancies were characterized. All models simulate forcings of comparable amplitude and exhibit a similar dependence on input parameters. As expected for a non-light-absorbing aerosol, forcings were negative (cooling influence) except at high surface albedo combined with small solar zenith angle. The relative standard deviation of the zenith-angle-averaged normalized broadband forcing for 15 models-was 8% for particle radius near the maximum in this forcing (approx. 0.2 microns) and at low surface albedo. Somewhat greater model-to-model discrepancies were exhibited at specific solar zenith angles. Still greater discrepancies were exhibited at small particle radii and much greater discrepancies were exhibited at high surface albedos, at which the forcing changes sign; in these situations, however, the normalized forcing is

  13. The application of mechanical aerosol delivery systems in an in vitro model of mechanically ventilated neonates.

    PubMed

    Ehtezazi, Touraj; Turner, Mark A

    2013-12-01

    Delivery of medication to the neonatal lung using current methods is inefficient. Aerosols offer one way to improve delivery to small airways. In this in vitro work, aerosol delivery by using a micropump or a rotary valve has been evaluated in a model of the neonatal setting with a pressurised metered dose inhaler plus spacer outside of the inspiratory limb. Drug depositions were assessed by spectrophotometric analyses. Drug lung deposition was increased by adjusting the rotary valve for co-ordination between the inhalation and aerosol delivery, but this intermittent mode decreased the aerosol delivery by using the micropump. Also, decreasing the volume of spacer decreased drug deposition in test lungs by using the micropump system. At the optimum conditions, the rotary valve aerosol delivery system delivered 3.68±0.91% of the Qvar nominal dose to the test lungs, and this was 2.34±0.01% for the micropump system. In conclusion, the rotary valve aerosol delivery system provided higher amounts of drug particles to the test lungs compared to the micropump system. The advantages of these methods were that the humidity in the ventilation circuit did not affect the aerosol particles in the spacer. Further optimisation is required to improve aerosol deposition in the test lungs. The article has also a short section of recent patents relevant to aerosol delivery.

  14. A general circulation model study of the global carbonaceous aerosol distribution

    NASA Astrophysics Data System (ADS)

    Cooke, W. F.; Ramaswamy, V.; Kasibhatla, P.

    2002-08-01

    Atmospheric distributions of carbonaceous aerosols are simulated using the Geophysical Fluid Dynamics Laboratory SKYHI general circulation model (GCM) (latitude-longitude resolution of ~3° × 3.6°). A number of systematic analyses are conducted to investigate the seasonal and interannual variability of the concentrations at specific locations and to investigate the sensitivity of the distributions to various physical parameters. Comparisons are made with several observational data sets. At four specific sites (Mace Head, Mauna Loa, Sable Island, and Bondville) the monthly mean measurements of surface concentrations of black carbon made over several years reveal that the model simulation registers successes as well as failures. Comparisons are also made with averages of measurements made over varying time periods, segregated by geography and rural/remote locations. Generally, the mean measured remote surface concentrations exceed those simulated. Notwithstanding the large variability in measurements and model simulations, the simulations of both black and organic carbon tend to be within about a factor of 2 at a majority of the sites. There are major challenges in conducting comparisons with measurements due to inadequate sampling at some sites, the generally short length of the observational record, and different methods used for estimating the black and organic carbon amounts. The interannual variability in the model and in the few such measurements available points to the need for doing multiyear modeling and to the necessity of comparing with long-term measurements. There are very few altitude profile measurements; notwithstanding the large uncertainties, the present comparisons suggest an overestimation by the model in the free troposphere. The global column burdens of black and organic carbon in the present standard model integration are lower than in previous studies and thus could be regarded as approximately bracketing a lower end of the simulated

  15. Dynamical model for thyroid

    NASA Astrophysics Data System (ADS)

    Rokni Lamooki, Gholam Reza; Shirazi, Amir H.; Mani, Ali R.

    2015-05-01

    Thyroid's main chemical reactions are employed to develop a mathematical model. The presented model is based on differential equations where their dynamics reflects many aspects of thyroid's behavior. Our main focus here is the well known, but not well understood, phenomenon so called as Wolff-Chaikoff effect. It is shown that the inhibitory effect of intake iodide on the rate of one single enzyme causes a similar effect as Wolff-Chaikoff. Besides this issue, the presented model is capable of revealing other complex phenomena of thyroid hormones homeostasis.

  16. Statistical Approaches to Aerosol Dynamics for Climate Simulation

    SciTech Connect

    Zhu, Wei

    2014-09-02

    In this work, we introduce two general non-parametric regression analysis methods for errors-in-variable (EIV) models: the compound regression, and the constrained regression. It is shown that these approaches are equivalent to each other and, to the general parametric structural modeling approach. The advantages of these methods lie in their intuitive geometric representations, their distribution free nature, and their ability to offer a practical solution when the ratio of the error variances is unknown. Each includes the classic non-parametric regression methods of ordinary least squares, geometric mean regression, and orthogonal regression as special cases. Both methods can be readily generalized to multiple linear regression with two or more random regressors.

  17. Evaluation of Black Carbon Estimations in Global Aerosol Models

    SciTech Connect

    Koch, D.; Schulz, M.; Kinne, Stefan; McNaughton, C. S.; Spackman, J. R.; Balkanski, Y.; Bauer, S.; Berntsen, T.; Bond, Tami C.; Boucher, Olivier; Chin, M.; Clarke, A. D.; De Luca, N.; Dentener, F.; Diehl, T.; Dubovik, O.; Easter, Richard C.; Fahey, D. W.; Feichter, J.; Fillmore, D.; Freitag, S.; Ghan, Steven J.; Ginoux, P.; Gong, S.; Horowitz, L.; Iversen, T.; Kirkevag, A.; Klimont, Z.; Kondo, Yutaka; Krol, M.; Liu, Xiaohong; Miller, R.; Montanaro, V.; Moteki, N.; Myhre, G.; Penner, J.; Perlwitz, Ja; Pitari, G.; Reddy, S.; Sahu, L.; Sakamoto, H.; Schuster, G.; Schwarz, J. P.; Seland, O.; Stier, P.; Takegawa, Nobuyuki; Takemura, T.; Textor, C.; van Aardenne, John; Zhao, Y.

    2009-11-27

    We evaluate black carbon (BC) model predictions from the AeroCom model intercomparison project by considering the diversity among year 2000 model simulations and comparing model predictions with available measurements. These model-measurement intercomparisons include BC surface and aircraft concentrations, aerosol absorption optical depth (AAOD) from AERONET and OMI retrievals and BC column estimations based on AERONET. In regions other than Asia, most models are biased high compared to surface concentration measurements. However compared with (column) AAOD or BC burden retreivals, the models are generally biased low. The average ratio of model to retrieved AAOD is less than 0.7 in South American and 0.6 in African biomass burning regions; both of these regions lack surface concentration measurements. In Asia the average model to observed ratio is 0.6 for AAOD and 0.5 for BC surface concentrations. Compared with aircraft measurements over the Americas at latitudes between 0 and 50N, the average model is a factor of 10 larger than observed, and most models exceed the measured BC standard deviation in the mid to upper troposphere. At higher latitudes the average model to aircraft BC is 0.6 and underestimate the observed BC loading in the lower and middle troposphere associated with springtime Arctic haze. Low model bias for AAOD but overestimation of surface and upper atmospheric BC concentrations at lower latitudes suggests that most models are underestimating BC absorption and should improve estimates for refractive index, particle size, and optical effects of BC coating. Retrieval uncertainties and/or differences with model diagnostic treatment may also contribute to the model-measurement disparity. Largest AeroCom model diversity occurred in northern Eurasia and the remote Arctic, regions influenced by anthropogenic sources. Changing emissions, aging, removal, or optical properties within a single model generated a smaller change in model predictions than the

  18. Epoxide pathways improve model predictions of isoprene markers and reveal key role of acidity in aerosol formation

    EPA Science Inventory

    Isoprene significantly contributes to organic aerosol in the southeastern United States where biogenic hydrocarbons mix with anthropogenic emissions. In this work, the Community Multiscale Air Quality model is updated to predict isoprene aerosol from epoxides produced under both ...

  19. Introductory lecture: atmospheric organic aerosols: insights from the combination of measurements and chemical transport models.

    PubMed

    Pandis, Spyros N; Donahue, Neil M; Murphy, Benjamin N; Riipinen, Ilona; Fountoukis, Christos; Karnezi, Eleni; Patoulias, David; Skyllakou, Ksakousti

    2013-01-01

    The formation, atmospheric evolution, properties, and removal of organic particulate matter remain some of the least understood aspects of atmospheric chemistry despite the importance of organic aerosol (OA) for both human health and climate change. Here, we summarize our recent efforts to deal with the chemical complexity of the tens of thousands of organic compounds in the atmosphere using the volatility-oxygen content framework (often called the 2D-Volatility Basis Set, 2D-VBS). Our current ability to measure the ambient OA concentration as a function of its volatility and oxygen to carbon (O:C) ratio is evaluated. The combination of a thermodenuder, isothermal dilution and Aerosol Mass Spectrometry (AMS) together with a mathematical aerosol dynamics model is a promising approach. The development of computational modules based on the 2D-VBS that can be used in chemical transport models (CTMs) is described. Approaches of different complexity are tested against ambient observations, showing the challenge of simulating the complex chemical evolution of atmospheric OA. The results of the simplest approach describing the net change due to functionalization and fragmentation are quite encouraging, reproducing both the observed OA levels and O : C in a variety of conditions. The same CTM coupled with source-apportionment algorithms can be used to gain insights into the travel distances and age of atmospheric OA. We estimate that the average age of OA near the ground in continental locations is 1-2 days and most of it was emitted (either as precursor vapors or particles) hundreds of kilometers away. Condensation of organic vapors on fresh particles is critical for the growth of these new particles to larger sizes and eventually to cloud condensation nuclei (CCN) sizes. The semivolatile organics currently simulated by CTMs are too volatile to condense on these tiny particles with high curvature. We show that chemical aging reactions converting these semivolatile

  20. A global average model of atmospheric aerosols for radiative transfer calculations

    NASA Technical Reports Server (NTRS)

    Toon, O. B.; Pollack, J. B.

    1976-01-01

    A global average model is proposed for the size distribution, chemical composition, and optical thickness of stratospheric and tropospheric aerosols. This aerosol model is designed to specify the input parameters to global average radiative transfer calculations which assume the atmosphere is horizontally homogeneous. The model subdivides the atmosphere at multiples of 3 km, where the surface layer extends from the ground to 3 km, the upper troposphere from 3 to 12 km, and the stratosphere from 12 to 45 km. A list of assumptions made in construction of the model is presented and discussed along with major model uncertainties. The stratospheric aerosol is modeled as a liquid mixture of 75% H2SO4 and 25% H2O, while the tropospheric aerosol consists of 60% sulfate and 40% soil particles above 3 km and of 50% sulfate, 35% soil particles, and 15% sea salt below 3 km. Implications and consistency of the model are discussed.

  1. Direct radiative effects of aerosols over South Asia from observations and modeling

    NASA Astrophysics Data System (ADS)

    Nair, Vijayakumar S.; Babu, S. Suresh; Manoj, M. R.; Moorthy, K. Krishna; Chin, Mian

    2016-10-01

    Quantitative assessment of the seasonal variations in the direct radiative effect (DRE) of composite aerosols as well as the constituent species over the Indian sub continent has been carried out using a synergy of observations from a dense network of ground based aerosol observatories and modeling based on chemical transport model simulations. Seasonal variation of aerosol constituents depict significant influence of anthropogenic aerosol sources in winter and the dominance of natural sources in spring, even though the aerosol optical depth doesn't change significantly between these two seasons. A significant increase in the surface cooling and atmospheric warming has been observed as season changes from winter (DRESUR = -28 ± 12 W m-2 and DREATM = +19.6 ± 9 W m-2) to spring (DRESUR = -33.7 ± 12 W m-2 and DREATM = +27 ± 9 W m-2). Interestingly, springtime aerosols are more absorptive in nature compared to winter and consequently the aerosol induced diabatic heating of the atmosphere goes as high as 1 K day-1 during spring, especially over eastern India. The atmospheric DRE due to dust aerosols (+14 ± 7 W m-2) during spring overwhelms that of black carbon DRE (+11.8 ± 6 W m-2) during winter. The DRE at the top of the atmosphere is mostly governed by the anthropogenic aerosols during all the seasons. The columnar aerosol loading, its anthropogenic fraction and radiative effects shows a steady increase with latitude across Indian mainland leading to a larger aerosol-induced atmospheric warming during spring than in winter.

  2. Modelling the chemically aged and mixed aerosols over the eastern central Atlantic Ocean - potential impacts

    NASA Astrophysics Data System (ADS)

    Astitha, M.; Kallos, G.; Spyrou, C.; O'Hirok, W.; Lelieveld, J.; Denier van der Gon, H. A. C.

    2010-07-01

    Detailed information on the chemical and physical properties of aerosols is important for assessing their role in air quality and climate. This work explores the origin and fate of continental aerosols transported over the Central Atlantic Ocean, in terms of chemical composition, number and size distribution, using chemistry-transport models, satellite data and in situ measurements. We focus on August 2005, a period with intense hurricane and tropical storm activity over the Atlantic Ocean. A mixture of anthropogenic (sulphates, nitrates), natural (desert dust, sea salt) and chemically aged (sulphate and nitrate on dust) aerosols is found entering the hurricane genesis region, most likely interacting with clouds in the area. Results from our modelling study suggest rather small amounts of accumulation mode desert dust, sea salt and chemically aged dust aerosols in this Atlantic Ocean region. Aerosols of smaller size (Aitken mode) are more abundant in the area and in some occasions sulphates of anthropogenic origin and desert dust are of the same magnitude in terms of number concentrations. Typical aerosol number concentrations are derived for the vertical layers near shallow cloud formation regimes, indicating that the aerosol number concentration can reach several thousand particles per cubic centimetre. The vertical distribution of the aerosols shows that the desert dust particles are often transported near the top of the marine cloud layer as they enter into the region where deep convection is initiated. The anthropogenic sulphate aerosol can be transported within a thick layer and enter the cloud deck through multiple ways (from the top, the base of the cloud, and by entrainment). The sodium (sea salt related) aerosol is mostly found below the cloud base. The results of this work may provide insights relevant for studies that consider aerosol influences on cloud processes and storm development in the Central Atlantic region.

  3. THERMODYNAMIC MODELING OF LIQUID AEROSOLS CONTAINING DISSOLVED ORGANICS AND ELECTROLYTES

    EPA Science Inventory

    Many tropospheric aerosols contain large fractions of soluble organic material, believed to derive from the oxidation of precursors such alpha-pinene. The chemical composition of aerosol organic matter is complex and not yet fully understood.

    The key properties of solu...

  4. Modeling Trends in Tropospheric Aerosol Burden & Its Radiative Effects

    EPA Science Inventory

    Large changes in emissions of aerosol precursors have occurred across the southeast U.S., North America, as well as the northern hemisphere. The spatial heterogeneity and contrasting trends in the aerosol burden is resulting in differing effects on regional radiative balance. Mul...

  5. Towards improved MODIS aerosol retrieval over the US East Coast region: Re-examining the aerosol model and surface assumptions

    NASA Astrophysics Data System (ADS)

    Levy, R. C.; Remer, L. A.; Kaufman, Y. J.; Holben, B. N.

    2002-12-01

    The MODerate resolution Imaging Spectrometer (MODIS) aboard the Terra and recently the Aqua platform, produces a set of aerosol products over both ocean and land regions. Previous validation efforts have shown that from a global perspective, aerosol optical depth (AOD) is successfully retrieved from MODIS. Even over coastal regions, the over-land and over-ocean retrievals are consistent with each other, and well matched with ground-based sunphotometer measurements (such as AERONET). However, the East Coast of the United States is one region where there is consistently a discrepancy between land and ocean retrievals. Over the ocean, MODIS AODs are consistent with coastal sunphotometer measurements, but over land, AODs are consistently over-estimated. In this study we use field data from the Chesapeake Lighthouse and Aircraft Measurements for Satellites experiment (CLAMS), (held during summer 2001) to determine the aerosol properties at a number of sites. Using the 6-S radiative transfer package, we compute simulated satellite radiances and compare them with observed MODIS radiances. We believe that the AOD over-estimation is not likely due to an incorrect choice of the urban/industrial aerosol models. Using 6-S to do an atmospheric correction for a very low AOD case, we show rather, that the discrepancies are likely a result of incorrect assumptions about the surface reflectance properties. Understanding and improving MODIS retrievals over the East Coast will not only improve the global quality of MODIS, but also would enable the use of MODIS as a tool for monitoring regional aerosol events.

  6. Modeling Fractal Dynamics

    NASA Astrophysics Data System (ADS)

    West, Bruce J.

    The proper methodology for describing the dynamics of certain complex phenomena and fractal time series is the fractional calculus through the fractional Langevin equation discussed herein and applied in a biomedical context. We show that a fractional operator (derivative or integral) acting on a fractal function, yields another fractal function, allowing us to construct a fractional Langevin equation to describe the evolution of a fractal statistical process, for example, human gait and cerebral blood flow. The goal of this talk is to make clear how certain complex phenomena, such as those that are abundantly present in human physiology, can be faithfully described using dynamical models involving fractional differential stochastic equations. These models are tested against existing data sets and shown to describe time series from complex physiologic phenomena quite well.

  7. Mesoscale ocean dynamics modeling

    SciTech Connect

    mHolm, D.; Alber, M.; Bayly, B.; Camassa, R.; Choi, W.; Cockburn, B.; Jones, D.; Lifschitz, A.; Margolin, L.; Marsden, L.; Nadiga, B.; Poje, A.; Smolarkiewicz, P.; Levermore, D.

    1996-05-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The ocean is a very complex nonlinear system that exhibits turbulence on essentially all scales, multiple equilibria, and significant intrinsic variability. Modeling the ocean`s dynamics at mesoscales is of fundamental importance for long-time-scale climate predictions. A major goal of this project has been to coordinate, strengthen, and focus the efforts of applied mathematicians, computer scientists, computational physicists and engineers (at LANL and a consortium of Universities) in a joint effort addressing the issues in mesoscale ocean dynamics. The project combines expertise in the core competencies of high performance computing and theory of complex systems in a new way that has great potential for improving ocean models now running on the Connection Machines CM-200 and CM-5 and on the Cray T3D.

  8. EDITORIAL: Aerosol cloud interactions—a challenge for measurements and modeling at the cutting edge of cloud climate interactions

    NASA Astrophysics Data System (ADS)

    Spichtinger, Peter; Cziczo, Daniel J.

    2008-04-01

    Research in aerosol properties and cloud characteristics have historically been considered two separate disciplines within the field of atmospheric science. As such, it has been uncommon for a single researcher, or even research group, to have considerable expertise in both subject areas. The recent attention paid to global climate change has shown that clouds can have a considerable effect on the Earth's climate and that one of the most uncertain aspects in their formation, persistence, and ultimate dissipation is the role played by aerosols. This highlights the need for researchers in both disciplines to interact more closely than they have in the past. This is the vision behind this focus issue of Environmental Research Letters. Certain interactions between aerosols and clouds are relatively well studied and understood. For example, it is known that an increase in the aerosol concentration will increase the number of droplets in warm clouds, decrease their average size, reduce the rate of precipitation, and extend the lifetime. Other effects are not as well known. For example, persistent ice super-saturated conditions are observed in the upper troposphere that appear to exceed our understanding of the conditions required for cirrus cloud formation. Further, the interplay of dynamics versus effects purely attributed to aerosols remains highly uncertain. The purpose of this focus issue is to consider the current state of knowledge of aerosol/cloud interactions, to define the contemporary uncertainties, and to outline research foci as we strive to better understand the Earth's climate system. This focus issue brings together laboratory experiments, field data, and model studies. The authors address issues associated with warm liquid water, cold ice, and intermediate temperature mixed-phase clouds. The topics include the uncertainty associated with the effect of black carbon and organics, aerosol types of anthropogenic interest, on droplet and ice formation. Phases

  9. Evaluation of the aerosol vertical distribution in global aerosol models through comparison against CALIOP measurements: AeroCom phase II results: AEROSOL PROFILES IN AEROCOM II GCM

    SciTech Connect

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

    2016-06-27

    The ability of eleven models in simulating the aerosol vertical distribution from regional to global scales, as part of the second phase of the AeroCom model inter-comparison initiative (AeroCom II) is assessed and compared to results of the first phase. The evaluation is performed using a global monthly gridded dataset of aerosol extinction profiles built on purpose from the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) Layer Product 3.01. Results over 12 sub-continental regions show that five models improved whereas three degraded in reproducing the Zα 0-6 km mean extinction height diagnostic, which is computed over the 0-6 km altitude range for each studied region and season. While the models’ performance remains highly variable, it has generally improved in terms of inter-regional diversity and seasonality. The biases in Zα 0-6 km have notably decreased in the U.S. and European industrial and downwind maritime regions, whereas the timing of the Zα 0-6 km peak season has improved for all but two models. However, most of the models now show a Zα 0-6 km underestimation over land, notably in the dust and biomass burning regions in Asia and Africa. At global scale, the AeroCom II models better reproduce the Zα 0-6 km latitudinal variability over ocean than over land. Hypotheses for the (changes in the) the performance of the individual models and for the inter-model diversity are discussed. We also provide an analysis of the CALIOP limitations and uncertainties that can contribute to the differences between the simulations and observations.

  10. The NASA-AMES Research Center Stratospheric Aerosol Model. 1. Physical Processes and Computational Analogs

    NASA Technical Reports Server (NTRS)

    Turco, R. P.; Hamill, P.; Toon, O. B.; Whitten, R. C.; Kiang, C. S.

    1979-01-01

    A time-dependent one-dimensional model of the stratospheric sulfate aerosol layer is presented. In constructing the model, a wide range of basic physical and chemical processes are incorporated in order to avoid predetermining or biasing the model predictions. The simulation, which extends from the surface to an altitude of 58 km, includes the troposphere as a source of gases and condensation nuclei and as a sink for aerosol droplets. The size distribution of aerosol particles is resolved into 25 categories with particle radii increasing geometrically from 0.01 to 2.56 microns such that particle volume doubles between categories.

  11. A simplified model of aerosol removal by natural processes in reactor containments

    SciTech Connect

    Powers, D.A.; Washington, K.E.; Sprung, J.L.; Burson, S.B.

    1996-07-01

    Simplified formulae are developed for estimating the aerosol decontamination that can be achieved by natural processes in the containments of pressurized water reactors and in the drywells of boiling water reactors under severe accident conditions. These simplified formulae were derived by correlation of results of Monte Carlo uncertainty analyses of detailed models of aerosol behavior under accident conditions. Monte Carlo uncertainty analyses of decontamination by natural aerosol processes are reported for 1,000, 2,000, 3,000, and 4,000 MW(th) pressurized water reactors and for 1,500, 2,500, and 3,500 MW(th) boiling water reactors. Uncertainty distributions for the decontamination factors and decontamination coefficients as functions of time were developed in the Monte Carlo analyses by considering uncertainties in aerosol processes, material properties, reactor geometry and severe accident progression. Phenomenological uncertainties examined in this work included uncertainties in aerosol coagulation by gravitational collision, Brownian diffusion, turbulent diffusion and turbulent inertia. Uncertainties in aerosol deposition by gravitational settling, thermophoresis, diffusiophoresis, and turbulent diffusion were examined. Electrostatic charging of aerosol particles in severe accidents is discussed. Such charging could affect both the coagulation and deposition of aerosol particles. Electrostatic effects are not considered in most available models of aerosol behavior during severe accidents and cause uncertainties in predicted natural decontamination processes that could not be taken in to account in this work. Median (50%), 90 and 10% values of the uncertainty distributions for effective decontamination coefficients were correlated with time and reactor thermal power. These correlations constitute a simplified model that can be used to estimate the decontamination by natural aerosol processes at 3 levels of conservatism. Applications of the model are described.

  12. Assessing the effects of anthropogenic aerosols on Pacific storm track using a multiscale global climate model

    PubMed Central

    Wang, Yuan; Wang, Minghuai; Zhang, Renyi; Ghan, Steven J.; Lin, Yun; Hu, Jiaxi; Pan, Bowen; Levy, Misti; Jiang, Jonathan H.; Molina, Mario J.

    2014-01-01

    Atmospheric aerosols affect weather and global general circulation by modifying cloud and precipitation processes, but the magnitude of cloud adjustment by aerosols remains poorly quantified and represents the largest uncertainty in estimated forcing of climate change. Here we assess the effects of anthropogenic aerosols on the Pacific storm track, using a multiscale global aerosol–climate model (GCM). Simulations of two aerosol scenarios corresponding to the present day and preindustrial conditions reveal long-range transport of anthropogenic aerosols across the north Pacific and large resulting changes in the aerosol optical depth, cloud droplet number concentration, and cloud and ice water paths. Shortwave and longwave cloud radiative forcing at the top of atmosphere are changed by −2.5 and +1.3 W m−2, respectively, by emission changes from preindustrial to present day, and an increased cloud top height indicates invigorated midlatitude cyclones. The overall increased precipitation and poleward heat transport reflect intensification of the Pacific storm track by anthropogenic aerosols. Hence, this work provides, for the first time to the authors’ knowledge, a global perspective of the effects of Asian pollution outflows from GCMs. Furthermore, our results suggest that the multiscale modeling framework is essential in producing the aerosol invigoration effect of deep convective clouds on a global scale. PMID:24733923

  13. Comparison of Modeled Backscatter using Measured Aerosol Microphysics with Focused CW Lidar Data over Pacific

    NASA Technical Reports Server (NTRS)

    Srivastava, Vandana; Clarke, Antony D.; Jarzembski, Maurice A.; Rothermel, Jeffry

    1997-01-01

    During NASA's GLObal Backscatter Experiment (GLOBE) II flight mission over the Pacific Ocean in May-June 1990, extensive aerosol backscatter data sets from two continuous wave, focused CO2 Doppler lidars and an aerosol microphysics data set from a laser optical particle counter (LOPC) were obtained. Changes in aerosol loading in various air masses with associated changes in chemical composition, from sulfuric acid and sulfates to dustlike crustal material, significantly affected aerosol backscatter, causing variation of about 3 to 4 orders of magnitude. Some of the significant backscatter features encountered in different air masses were the low backscatter in subtropical air with even lower values in the tropics near the Intertropical Convergence Zone (ITCZ), highly variable backscatter in the ITCZ, mid-tropospheric aerosol backscatter background mode, and high backscatter in an Asian dust plume off the Japanese coast. Differences in aerosol composition and backscatter for northern and southern hemisphere also were observed. Using the LOPC measurements of physical and chemical aerosol properties, we determined the complex refractive index from three different aerosol mixture models to calculate backscatter. These values provided a well-defined envelope of modeled backscatter for various atmospheric conditions, giving good agreement with the lidar data over a horizontal sampling of approximately 18000 km in the mid-troposphere.

  14. Topochemical diffusion-reaction-convection dynamics in vapor-to-particle aerosol nucleation and growth

    NASA Astrophysics Data System (ADS)

    Thompson, Stephen; Shipman, Patrick D.

    2013-05-01

    We report on patterns and oscillations observed in topochemically organized vapor-toparticle experimental systems involving aerosol nucleation and growth processes in which NH3 reacts with HCl, HNO3, H2SO4, and CH3COOH. Mathematical models of these systems in comparison with experiments allow us to estimate parameters such as kinetic constants and nucleation thresholds. The patterns are strongly influenced by charging, hydration, and turbulence driven by exothermicity.

  15. Evaluating the representation of aerosol optical properties using an online coupled model over the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Palacios-Peña, Laura; Baró, Rocío; Guerrero-Rascado, Juan Luis; Alados-Arboledas, Lucas; Brunner, Dominik; Jiménez-Guerrero, Pedro

    2017-01-01

    The effects of atmospheric aerosol particles on the Earth's climate mainly depend on their optical, microphysical and chemical properties, which modify the Earth's radiative budget. The aerosol radiative effects can be divided into direct and semi-direct effects, produced by the aerosol-radiation interactions (ARIs), and indirect effects, produced by aerosol-cloud interactions (ACIs). In this sense the objective of this work is to assess whether the inclusion of aerosol radiative feedbacks in the online coupled WRF-Chem model improves the modelling outputs over the Iberian Peninsula (IP) and surrounding water areas. For this purpose, the methodology is based on the evaluation of modelled aerosol optical properties under different simulation scenarios. The evaluated data come from two WRF-Chem simulations for the IP differing in the inclusion/no-inclusion of ARIs and ACIs (RF/NRF simulations). The case studies cover two episodes with different aerosol types over the IP in 2010, namely a Saharan dust outbreak and a forest fire episode. The evaluation uses observational data from AERONET (Aerosol Robotic Network) stations and MODIS (Moderate Resolution Imaging Spectroradiometer) sensor, including aerosol optical depth (AOD) and Ångström exponent (AE). Experimental data of aerosol vertical distribution from the EARLINET (European Aerosol Research Lidar Network) Granada station are used for checking the models. The results indicate that for the spatial distribution the best-represented variable is AOD and the largest improvements when including the aerosol radiative feedbacks are found for the vertical distribution. In the case of the dust outbreak, a slight improvement (worsening) is produced over the areas with medium (high/low) levels of AOD(-9 % / +12 % of improvement) when including the aerosol radiative feedbacks. For the wildfire episode, improvements of AOD representation (up to 11 %) over areas further away from emission sources are estimated

  16. Assessment of the aerosol distribution over Indian subcontinent in CMIP5 models

    NASA Astrophysics Data System (ADS)

    Sanap, S. D.; Ayantika, D. C.; Pandithurai, G.; Niranjan, K.

    2014-04-01

    This paper examines the aerosol distribution over Indian subcontinent as represented in 21 models from Coupled Model Inter-comparison Project Phase 5 (CMIP5) simulations, wherein model simulated aerosol optical depth (AOD) is compared with Moderate Resolution Imaging Spectro-radiometer (MODIS) satellite observations. The objective of the study is to provide an assessment of the capability of various global models, participating in CMIP5 project, in capturing the realistic spatial and temporal distribution of aerosol species over the Indian subcontinent. Results from our analysis show that majority of the CMIP5 models (excepting HADGEM2-ES, HADGEM2-CC) seriously underestimates the spatio-temporal variability of aerosol species over the Indian subcontinent, in particular over Indo-Gangetic Plains (IGP). Since IGP region is dominated by anthropogenic activities, high population density, and wind driven transport of dust and other aerosol species, MODIS observations reveal high AOD values over this region. Though the representation of black carbon (BC) loading in many models is fairly good, the dust loading is observed to be significantly low in majority of the models. The presence of pronounced dust activity over northern India and dust being one of the major constituent of aerosol species, the biases in dust loading has a great impact on the AOD of that region. We found that considerable biases in simulating the 850 hPa wind field (which plays important role in transport of dust from adjacent deserts) would be the possible reason for poor representation of dust AOD and in turn total AOD over Indian region in CMIP5 models. In addition, aerosol radiative forcing (ARF) underestimated/overestimated in most of the models. However, spatial distribution of ARF in multi-model ensemble mean is comparable reasonably well with observations with bias in magnitudes. This analysis emphasizes the fundamental need to improve the representation of aerosol species in current state of

  17. Aerosol distributions and radiative forcing over the Asian Pacific region simulated by Spectral Radiation-Transport Model for Aerosol Species (SPRINTARS)

    NASA Astrophysics Data System (ADS)

    Takemura, Toshihiko; Nakajima, Teruyuki; Higurashi, Akiko; Ohta, Sachio; Sugimoto, Nobuo

    2003-12-01

    A three-dimensional aerosol transport-radiation model coupled with a general circulation model, Spectral Radiation-Transport Model for Aerosol Species (SPRINTARS), simulates atmospheric aerosol distributions and optical properties. The simulated results are compared with aerosol sampling and optical observations from ground, aircraft, and satellite acquired by intensive observation campaigns over east Asia in spring 2001. Temporal variations of the aerosol concentrations, optical thickness, and Ångström exponent are in good agreement between the simulation and observations. The midrange values of the Ångström exponent, even at the Asian dust storm events over the outflow regions, suggest that the contribution of the anthropogenic aerosol, such as carbonaceous and sulfate, to the total optical thickness is of an order comparable to that of the Asian dust. The radiative forcing by the aerosol direct and indirect effects is also calculated. The negative direct radiative forcing is simulated to be over -10 W m-2 at the tropopause in the air mass during the large-scale dust storm, to which both anthropogenic aerosols and Asian dust contribute almost equivalently. The direct radiative forcing, however, largely depends on the cloud water content and the vertical profiles of aerosol and cloud. The simulation shows that not only sulfate and sea salt aerosols but also black carbon and soil dust aerosols, which absorb solar and thermal radiation, make strong negative radiative forcing by the direct effect at the surface, which may exceed the positive forcing by anthropogenic greenhouse gases over the east Asian region.

  18. Coupling aerosol optics to the MATCH (v5.5.0) chemical transport model and the SALSA (v1) aerosol microphysics module

    NASA Astrophysics Data System (ADS)

    Andersson, Emma; Kahnert, Michael

    2016-05-01

    A new aerosol-optics model is implemented in which realistic morphologies and mixing states are assumed, especially for black carbon particles. The model includes both external and internal mixing of all chemical species, it treats externally mixed black carbon as fractal aggregates, and it accounts for inhomogeneous internal mixing of black carbon by use of a novel "core-grey-shell" model. Simulated results of aerosol optical properties, such as aerosol optical depth, backscattering coefficients and the Ångström exponent, as well as radiative fluxes are computed with the new optics model and compared with results from an older optics-model version that treats all particles as externally mixed homogeneous spheres. The results show that using a more detailed description of particle morphology and mixing state impacts the aerosol optical properties to a degree of the same order of magnitude as the effects of aerosol-microphysical processes. For instance, the aerosol optical depth computed for two cases in 2007 shows a relative difference between the two optics models that varies over the European region between -28 and 18 %, while the differences caused by the inclusion or omission of the aerosol-microphysical processes range from -50 to 37 %. This is an important finding, suggesting that a simple optics model coupled to a chemical transport model can introduce considerable errors affecting radiative fluxes in chemistry-climate models, compromising comparisons of model results with remote sensing observations of aerosols, and impeding the assimilation of satellite products for aerosols into chemical-transport models.

  19. Global Radiative Forcing of Coupled Tropospheric Ozone and Aerosols in a Unified General Circulation Model

    NASA Technical Reports Server (NTRS)

    Liao, Hong; Seinfeld, John H.; Adams, Peter J.; Mickley, Loretta J.

    2008-01-01

    Global simulations of sea salt and mineral dust aerosols are integrated into a previously developed unified general circulation model (GCM), the Goddard Institute for Space Studies (GISS) GCM II', that simulates coupled tropospheric ozone-NOx-hydrocarbon chemistry and sulfate, nitrate, ammonium, black carbon, primary organic carbon, and secondary organic carbon aerosols. The fully coupled gas-aerosol unified GCM allows one to evaluate the extent to which global burdens, radiative forcing, and eventually climate feedbacks of ozone and aerosols are influenced by gas-aerosol chemical interactions. Estimated present-day global burdens of sea salt and mineral dust are 6.93 and 18.1 Tg with lifetimes of 0.4 and 3.9 days, respectively. The GCM is applied to estimate current top of atmosphere (TOA) and surface radiative forcing by tropospheric ozone and all natural and anthropogenic aerosol components. The global annual mean value of the radiative forcing by tropospheric ozone is estimated to be +0.53 W m(sup -2) at TOA and +0.07 W m(sup -2) at the Earth's surface. Global, annual average TOA and surface radiative forcing by all aerosols are estimated as -0.72 and -4.04 W m(sup -2), respectively. While the predicted highest aerosol cooling and heating at TOA are -10 and +12 W m(sup -2) respectively, surface forcing can reach values as high as -30 W m(sup -2), mainly caused by the absorption by black carbon, mineral dust, and OC. We also estimate the effects of chemistry-aerosol coupling on forcing estimates based on currently available understanding of heterogeneous reactions on aerosols. Through altering the burdens of sulfate, nitrate, and ozone, heterogeneous reactions are predicted to change the global mean TOA forcing of aerosols by 17% and influence global mean TOA forcing of tropospheric ozone by 15%.

  20. Thermodynamic Modeling of Organic-Inorganic Aerosols with the Group-Contribution Model AIOMFAC

    NASA Astrophysics Data System (ADS)

    Zuend, A.; Marcolli, C.; Luo, B. P.; Peter, T.

    2009-04-01

    Liquid aerosol particles are - from a physicochemical viewpoint - mixtures of inorganic salts, acids, water and a large variety of organic compounds (Rogge et al., 1993; Zhang et al., 2007). Molecular interactions between these aerosol components lead to deviations from ideal thermodynamic behavior. Strong non-ideality between organics and dissolved ions may influence the aerosol phases at equilibrium by means of liquid-liquid phase separations into a mainly polar (aqueous) and a less polar (organic) phase. A number of activity models exists to successfully describe the thermodynamic equilibrium of aqueous electrolyte solutions. However, the large number of different, often multi-functional, organic compounds in mixed organic-inorganic particles is a challenging problem for the development of thermodynamic models. The group-contribution concept as introduced in the UNIFAC model by Fredenslund et al. (1975), is a practical method to handle this difficulty and to add a certain predictability for unknown organic substances. We present the group-contribution model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients), which explicitly accounts for molecular interactions between solution constituents, both organic and inorganic, to calculate activities, chemical potentials and the total Gibbs energy of mixed systems (Zuend et al., 2008). This model enables the computation of vapor-liquid (VLE), liquid-liquid (LLE) and solid-liquid (SLE) equilibria within one framework. Focusing on atmospheric applications we considered eight different cations, five anions and a wide range of alcohols/polyols as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are very well represented up to high ionic strength. We show that the semi-empirical middle-range parametrization of direct organic-inorganic interactions in alcohol-water-salt solutions enables accurate computations of vapor-liquid and liquid

  1. Contact dynamics math model

    NASA Technical Reports Server (NTRS)

    Glaese, John R.; Tobbe, Patrick A.

    1986-01-01

    The Space Station Mechanism Test Bed consists of a hydraulically driven, computer controlled six degree of freedom (DOF) motion system with which docking, berthing, and other mechanisms can be evaluated. Measured contact forces and moments are provided to the simulation host computer to enable representation of orbital contact dynamics. This report describes the development of a generalized math model which represents the relative motion between two rigid orbiting vehicles. The model allows motion in six DOF for each body, with no vehicle size limitation. The rotational and translational equations of motion are derived. The method used to transform the forces and moments from the sensor location to the vehicles' centers of mass is also explained. Two math models of docking mechanisms, a simple translational spring and the Remote Manipulator System end effector, are presented along with simulation results. The translational spring model is used in an attempt to verify the simulation with compensated hardware in the loop results.

  2. Separating Real and Apparent Effects of Cloud, Humidity, and Dynamics on Aerosol Optical Thickness near Cloud Edges

    NASA Technical Reports Server (NTRS)

    Jeong, Myeong-Jae; Li, Zhanqing

    2010-01-01

    Aerosol optical thickness (AOT) is one of aerosol parameters that can be measured on a routine basis with reasonable accuracy from Sun-photometric observations at the surface. However, AOT-derived near clouds is fraught with various real effects and artifacts, posing a big challenge for studying aerosol and cloud interactions. Recently, several studies have reported correlations between AOT and cloud cover, pointing to potential cloud contamination and the aerosol humidification effect; however, not many quantitative assessments have been made. In this study, various potential causes of apparent correlations are investigated in order to separate the real effects from the artifacts, using well-maintained observations from the Aerosol Robotic Network, Total Sky Imager, airborne nephelometer, etc., over the Southern Great Plains site operated by the U.S. Department of Energy's Atmospheric Radiation Measurement Program. It was found that aerosol humidification effects can explain about one fourth of the correlation between the cloud cover and AOT. New particle genesis, cloud-processed particles, atmospheric dynamics, and aerosol indirect effects are likely to be contributing to as much as the remaining three fourth of the relationship between cloud cover and AOT.

  3. Climatic impact of urbanization in Eastern China: modeling the combined urban heat island and aerosol effects

    NASA Astrophysics Data System (ADS)

    Qian, Y.; Yang, B.; Zhao, C.; Leung, L. R.; Yan, H.; Fan, J.

    2014-12-01

    In this study we investigate the climatic impact of urbanization, including both Urban Heat Island (UHI) and aerosol effects, over the Yangtze-Delta metropolitan clusters region of Eastern China, based on a series of simulations with prescribed land use/land cover and emissions of aerosols and their precursors for the 2000s and 1970s , respectively. We conduct simulations for each land use/land cover and emission scenario from 2006-2010 using the Weather Research and Forecasting (WRF) model, with online chemistry/aerosol and urban canopy models, at a 3-km grid spacing. Overall the model can reasonably capture the spatial pattern of temperature and precipitation as well as the phase of precipitation diurnal cycle in summer. Simulations results show a very clear UHI effect, i.e. expanded urban surface decreases surface latent heat flux, increases sensible heat flux and PBL height, and reduces surface wind over urban areas, with a more significant change in summer. Aerosol has much less obvious impact on local surface heat flux and temperature, but shows more remote impacts downwind due to dispersion and transport of pollutants and aerosol-cloud interaction. Aerosol also has a larger impact on precipitation amount and areal coverage than UHI. While UHI increases precipitation over urban regions during daytime especially when the southeasterly monsoonal flow prevails, aerosol remarkably suppresses precipitation, especially for light to moderate rain events, and increases the frequency of dry days in the entire model region.

  4. Climate studies with a multilayer energy balance model. III - Climatic impact of stratospheric volcanic aerosols

    NASA Technical Reports Server (NTRS)

    Chou, M.-D.; Arking, A.; Peng, L.

    1984-01-01

    A multilayer energy balance model is applied in an examination of the sensitivity of climate to stratospheric aerosols induced by volcanic eruptions. Zonally and annually averaged quantities are considered, with ocean and land temperatures computed separately and the atmosphere below the 200 mb level divided into eight layers of 24 sublayers each. The aerosol is assumed to form in the 150-200 mb range. Aerosol parameters for radiative transfer calculations are reflection in the solar spectral region and absorption in the solar and IR regions. A 75 percent aqueous solution of sulfuric acid is assumed for the aerosols. The sensitivity of the hemispherically averaged surface temperature is enhanced 37 percent, with a 20 percent uncertainty, when the thermal IR radiation is excluded. The solar radiation enhances the surface temperatures to a higher degree than the thermal radiation. The maximum response to the evenly distributed aerosols is in the 60-70 deg N latitudes and propagates, weakening, to lower latitudes.

  5. Response of different regional online coupled models to aerosol-radiation interactions

    NASA Astrophysics Data System (ADS)

    Forkel, Renate; Balzarini, Alessandra; Brunner, Dominik; Baró, Rocio; Curci, Gabriele; Hirtl, Marcus; Honzak, Luka; Jiménez-Guerrero, Pedro; Jorba, Oriol; Pérez, Juan L.; Pirovano, Guido; San José, Roberto; Schröder, Wolfram; Tuccella, Paolo; Werhahn, Johannes; Wolke, Ralf; Žabkar, Rahela

    2016-04-01

    The importance of aerosol-meteorology interactions and their representation in online coupled regional atmospheric chemistry-meteorology models was investigated in COST Action ES1004 (EuMetChem, http://eumetchem.info/). Case study results from different models (COSMO-Muscat, COSMO-ART, and different configurations of WRF-Chem), which were applied for Europe as a coordinated exercise for the year 2010, are analyzed with respect to inter-model variability and the response of the different models to direct and indirect aerosol-radiation interactions. The main focus was on two episodes - the Russian heat wave and wildfires episode in July/August 2010 and a period in October 2010 with enhanced cloud cover and rain and including an of Saharan dust transport to Europe. Looking at physical plausibility the decrease in downward solar radiation and daytime temperature due to the direct aerosol effect is robust for all model configurations. The same holds for the pronounced decrease in cloud water content and increase in solar radiation for cloudy conditions and very low aerosol concentrations that was found for WRF-Chem when aerosol cloud interactions were considered. However, when the differences were tested for statistical significance no significant differences in mean solar radiation and mean temperature between the baseline case and the simulations including the direct and indirect effect from simulated aerosol concentrations were found over Europe for the October episode. Also for the fire episode differences between mean temperature and radiation from the simulations with and without the direct aerosol effect were not significant for the major part of the modelling domain. Only for the region with high fire emissions in Russia, the differences in mean solar radiation and temperature due to the direct effect were found to be significant during the second half of the fire episode - however only for a significance level of 0.1. The few observational data indicate that

  6. Constraining aerosol optical models using ground-based, collocated particle size and mass measurements in variable air mass regimes during the 7-SEAS/Dongsha experiment

    NASA Astrophysics Data System (ADS)

    Bell, Shaun W.; Hansell, Richard A.; Chow, Judith C.; Tsay, Si-Chee; Hsu, N. Christina; Lin, Neng-Huei; Wang, Sheng-Hsiang; Ji, Qiang; Li, Can; Watson, John G.; Khlystov, Andrey

    2013-10-01

    During the spring of 2010, NASA Goddard's COMMIT ground-based mobile laboratory was stationed on Dongsha Island off the southwest coast of Taiwan, in preparation for the upcoming 2012 7-SEAS field campaign. The measurement period offered a unique opportunity for conducting detailed investigations of the optical properties of aerosols associated with different air mass regimes including background maritime and those contaminated by anthropogenic air pollution and mineral dust. What appears to be the first time for this region, a shortwave optical closure experiment (λ = 550 nm) for both scattering and absorption was attempted over a 12-day period during which aerosols exhibited the most change. Constraints to the optical model included combined SMPS and APS number concentration data for a continuum of fine and coarse-mode particle sizes up to PM2.5. We also take advantage of an IMPROVE chemical sampler to help constrain aerosol composition and mass partitioning of key elemental species including sea-salt, particulate organic matter, soil, non sea-salt sulfate, nitrate, and elemental carbon. Achieving full optical closure is hampered by limitations in accounting for the role of water vapor in the system, uncertainties in the instruments and the need for further knowledge in the source apportionment of the model's major chemical components. Nonetheless, our results demonstrate that the observed aerosol scattering and absorption for these diverse air masses are reasonably captured by the model, where peak aerosol events and transitions between key aerosols types are evident. Signatures of heavy polluted aerosol composed mostly of ammonium and non sea-salt sulfate mixed with some dust with transitions to background sea-salt conditions are apparent in the absorption data, which is particularly reassuring owing to the large variability in the imaginary component of the refractive indices. Consistency between the measured and modeled optical parameters serves as an

  7. Constraining Aerosol Optical Models Using Ground-Based, Collocated Particle Size and Mass Measurements in Variable Air Mass Regimes During the 7-SEAS/Dongsha Experiment

    NASA Technical Reports Server (NTRS)

    Bell, Shaun W.; Hansell, Richard A.; Chow, Judith C.; Tsay, Si-Chee; Wang, Sheng-Hsiang; Ji, Qiang; Li, Can; Watson, John G.; Khlystov, Andrey

    2012-01-01

    During the spring of 2010, NASA Goddard's COMMIT ground-based mobile laboratory was stationed on Dongsha Island off the southwest coast of Taiwan, in preparation for the upcoming 2012 7-SEAS field campaign. The measurement period offered a unique opportunity for conducting detailed investigations of the optical properties of aerosols associated with different air mass regimes including background maritime and those contaminated by anthropogenic air pollution and mineral dust. What appears to be the first time for this region, a shortwave optical closure experiment for both scattering and absorption was attempted over a 12-day period during which aerosols exhibited the most change. Constraints to the optical model included combined SMPS and APS number concentration data for a continuum of fine and coarse-mode particle sizes up to PM2.5. We also take advantage of an IMPROVE chemical sampler to help constrain aerosol composition and mass partitioning of key elemental species including sea-salt, particulate organic matter, soil, non sea-salt sulphate, nitrate, and elemental carbon. Our results demonstrate that the observed aerosol scattering and absorption for these diverse air masses are reasonably captured by the model, where peak aerosol events and transitions between key aerosols types are evident. Signatures of heavy polluted aerosol composed mostly of ammonium and non sea-salt sulphate mixed with some dust with transitions to background sea-salt conditions are apparent in the absorption data, which is particularly reassuring owing to the large variability in the imaginary component of the refractive indices. Extinctive features at significantly smaller time scales than the one-day sample period of IMPROVE are more difficult to reproduce, as this requires further knowledge concerning the source apportionment of major chemical components in the model. Consistency between the measured and modeled optical parameters serves as an important link for advancing remote

  8. Process-model simulations of cloud albedo enhancement by aerosols in the Arctic.

    PubMed

    Kravitz, Ben; Wang, Hailong; Rasch, Philip J; Morrison, Hugh; Solomon, Amy B

    2014-12-28

    A cloud-resolving model is used to simulate the effectiveness of Arctic marine cloud brightening via injection of cloud condensation nuclei (CCN), either through geoengineering or other increased sources of Arctic aerosols. An updated cloud microphysical scheme is employed, with prognostic CCN and cloud particle numbers in both liquid and mixed-phase marine low clouds. Injection of CCN into the marine boundary layer can delay the collapse of the boundary layer and increase low-cloud albedo. Albedo increases are stronger for pure liquid clouds than mixed-phase clouds. Liquid precipitation can be suppressed by CCN injection, whereas ice precipitation (snow) is affected less; thus, the effectiveness of brightening mixed-phase clouds is lower than for liquid-only clouds. CCN injection into a clean regime results in a greater albedo increase than injection into a polluted regime, consistent with current knowledge about aerosol-cloud interactions. Unlike previous studies investigating warm clouds, dynamical changes in circulation owing to precipitation changes are small. According to these results, which are dependent upon the representation of ice nucleation processes in the employed microphysical scheme, Arctic geoengineering is unlikely to be effective as the sole means of altering the global radiation budget but could have substantial local radiative effects.

  9. Model Representation of Secondary Organic Aerosol in CMAQ v4.7

    EPA Science Inventory

    Numerous scientific upgrades to the representation of secondary organic aerosol (SOA) are incorporated into the Community Multiscale Air Quality (CMAQ) modeling system. Additions include several recently identified SOA precursors: benzene, isoprene, and sesquiterpenes; and pathwa...

  10. Aerosol Resuspension Model for MELCOR for Fusion and Very High Temperature Reactor Applications

    SciTech Connect

    B.J. Merrill

    2011-01-01

    Dust is generated in fusion reactors from plasma erosion of plasma facing components within the reactor’s vacuum vessel (VV) during reactor operation. This dust collects in cooler regions on interior surfaces of the VV. Because this dust can be radioactive, toxic, and/or chemically reactive, it poses a safety concern, especially if mobilized by the process of resuspension during an accident and then transported as an aerosol though out the reactor confinement building, and possibly released to the environment. A computer code used at the Idaho National Laboratory (INL) to model aerosol transport for safety consequence analysis is the MELCOR code. A primary reason for selecting MELCOR for this application is its aerosol transport capabilities. The INL Fusion Safety Program (FSP) organization has made fusion specific modifications to MELCOR. Recent modifications include the implementation of aerosol resuspension models in MELCOR 1.8.5 for Fusion. This paper presents the resuspension models adopted and the initial benchmarking of these models.

  11. Development of prognostic aerosol-cloud interactions combining a chemistry transport model and a regional climate model

    NASA Astrophysics Data System (ADS)

    Thomas, M. A.; Kahnert, M.; Andersson, C.; Kokkola, H.; Hansson, U.; Jones, C.; Langner, J.; Devasthale, A.

    2015-02-01

    To reduce uncertainties and hence, to obtain a better estimate of aerosol (direct and indirect) radiative forcing, next generation climate models aim for a tighter coupling between chemistry transport models and regional climate models and a better representation of aerosol-cloud interactions. In this study, this coupling is done by first forcing the Rossby Center regional climate model, RCA4 by ERA-Interim lateral boundaries (LBCs) and SST using the standard CDNC (cloud droplet number concentration) formulation (hereafter, referred to as the "stand-alone RCA4 version" or "CTRL" simulation). In this simulation, the CDNCs are assigned fixed numbers based on if the underlying surface is land or oceanic. The meteorology from this simulation is then used to drive the chemistry transport model, MATCH which is coupled online with the aerosol dynamics model, SALSA. CDNC fields obtained from MATCH-SALSA are then fed back into a new RCA4 simulation. In this new simulation (referred to as "MOD" simulation), all parameters remain the same as in the first run except for the CDNCs provided by MATCH-SALSA. Simulations are carried out with this model set up for the period 2005-2012 over Europe and the differences in cloud microphysical properties and radiative fluxes as a result of local CDNC changes and possible model responses are analyzed. Our study shows substantial improvements in the cloud microphysical properties with the input of the MATCH-SALSA derived 3-D CDNCs compared to the stand-alone RCA4 version. This model set up improves the spatial, seasonal and vertical distribution of CDNCs with higher concentration observed over central Europe during summer half of the year and over Eastern Europe and Russia during the winter half of the year. Realistic cloud droplet radii (CD radii) values have been simulated with the maxima reaching 13 μm whereas in the stand-alone version, the values reached only 5 μm. A substantial improvement in the distribution of cloud liquid water

  12. Can we better use existing and emerging computing hardware to embed activity coefficient predictions in complex atmospheric aerosol models?

    NASA Astrophysics Data System (ADS)

    Topping, David; Alibay, Irfan; Ruske, Simon; Hindriksen, Vincent; Noisternig, Michael

    2016-04-01

    To predict the evolving concentration, chemical composition and ability of aerosol particles to act as cloud droplets, we rely on numerical modeling. Mechanistic models attempt to account for the movement of compounds between the gaseous and condensed phases at a molecular level. This 'bottom up' approach is designed to increase our fundamental understanding. However, such models rely on predicting the properties of molecules and subsequent mixtures. For partitioning between the gaseous and condensed phases this includes: saturation vapour pressures; Henrys law coefficients; activity coefficients; diffusion coefficients and reaction rates. Current gas phase chemical mechanisms predict the existence of potentially millions of individual species. Within a dynamic ensemble model, this can often be used as justification for neglecting computationally expensive process descriptions. Indeed, on whether we can quantify the true sensitivity to uncertainties in molecular properties, even at the single aerosol particle level it has been impossible to embed fully coupled representations of process level knowledge with all possible compounds, typically relying on heavily parameterised descriptions. Relying on emerging numerical frameworks, and designed for the changing landscape of high-performance computing (HPC), in this study we show that comprehensive microphysical models from single particle to larger scales can be developed to encompass a complete state-of-the-art knowledge of aerosol chemical and process diversity. We focus specifically on the ability to capture activity coefficients in liquid solutions using the UNIFAC method, profiling traditional coding strategies and those that exploit emerging hardware.

  13. A Simple Model for the Cloud Adjacency Effect and the Apparent Bluing of Aerosols Near Clouds

    NASA Technical Reports Server (NTRS)

    Marshak, Alexander; Wen, Guoyong; Coakley, James A., Jr.; Remer, Lorraine A.; Loeb,Norman G.; Cahalan, Robert F.

    2008-01-01

    In determining aerosol-cloud interactions, the properties of aerosols must be characterized in the vicinity of clouds. Numerous studies based on satellite observations have reported that aerosol optical depths increase with increasing cloud cover. Part of the increase comes from the humidification and consequent growth of aerosol particles in the moist cloud environment, but part comes from 3D cloud-radiative transfer effects on the retrieved aerosol properties. Often, discerning whether the observed increases in aerosol optical depths are artifacts or real proves difficult. The paper provides a simple model that quantifies the enhanced illumination of cloud-free columns in the vicinity of clouds that are used in the aerosol retrievals. This model is based on the assumption that the enhancement in the cloud-free column radiance comes from enhanced Rayleigh scattering that results from the presence of the nearby clouds. The enhancement in Rayleigh scattering is estimated using a stochastic cloud model to obtain the radiative flux reflected by broken clouds and comparing this flux with that obtained with the molecules in the atmosphere causing extinction, but no scattering.

  14. ISA-MIP: A co-ordinated intercomparison of Interactive Stratospheric Aerosol models

    NASA Astrophysics Data System (ADS)

    Timmreck, Claudia; Mann, Graham; Aquila, Valentina; Bruehl, Christoph; Chin, Mian; Dohmse, Sandip; English, Jason; Lee, Lindsay; Mills, Michael; Hommel, Rene; Neely, Ryan; Schmidt, Anja; Sheng, Jianxiong; Toohey, Matthew; Weisenstein, Debra

    2016-04-01

    The SPARC activity, "Stratospheric Sulfur and its Role in Climate" (SSiRC) was initiated to coordinate international research activities on modelling and observation of stratospheric sulphate aerosols (and precursor gases) in order to assess its climate forcing and feedback. With several international activities to extend and improve observational stratospheric aerosol capabilities and data sets, and a growing number of global models treating stratospheric aerosol interactively, a new model intercomparison activity "ISA-MIP" has been established in the frame of SSIRC. ISA-MIP will compare interactive stratospheric aerosol (ISA) models using a range of observations to constrain and improve the models and to provide a sound scientific basis for future work. Four ISA-MIP experiments have been designed to assess different periods of the obervational stratospheric aerosol record, and to explore key processes which influence the formation and temporal development of stratospheric aerosol. The "Background" experiment will focus on the role of microphysical and transport processes under volcanically quiescent conditions, where the stratospheric aerosol size distribution is only modulated by seasonal circulations. The "Model intercomparison of Transient Aerosol Record" (MiTAR) experiment will focus on addressing the role of small- to moderate-magnitude volcanic eruptions and transport processes in the upper troposphere - lower stratosphere (UTLS) aerosols loading over the period 1998-2011. Background and MiTAR simulations will be compared to recent in-situ and satellite observations to evaluate the performances of the model and understand their strengths and weaknesses. Two further experiments investigate the radiative forcing from historical major eruptions. The Historical Eruptions SO2 Emission Assessment (HErSEA) will involve models carrying out mini-ensembles of the stratospheric aerosol perturbations from each of the 1963 Agung, 1982 El Chichon and 1991 Pinatubo

  15. Assessment of the Aerosol Distribution Over Indian Subcontinent in CMIP5 Models

    NASA Astrophysics Data System (ADS)

    Sanap, S. D.; Pandithurai, G.

    2014-12-01

    This paper examines the aerosol distribution over Indian subcontinent as represented in 21 models from Coupled Model Inter-comparison Project Phase 5 (CMIP5) simulations, wherein model simulated aerosol optical depth (AOD) is compared with Moderate Resolution Imaging Spectro-radiometer (MODIS) satellite observations. The objective of the study is to provide an assessment of the capability of various global models, participating in CMIP5 project, in capturing the realistic spatial and temporal distribution of aerosol species over the Indian subcontinent. Results from our analysis show that majority of the CMIP5 models seriously underestimates the spatio-temporal variability of aerosol species over the Indian subcontinent, in particular over Indo-Gangetic Plains(IGP). Though the representation of black carbon (BC) loading in many models is fairly good, the dust loading is observed to be significantly low in majority of the models. The presence of pronounced dust activity over northern India and dust being one of the major constituent of aerosol species, the biases in dust loading has a great impact on the AOD of that region. We found that considerable biases in simulating the 850 hPa wind field (which plays important role in transport of dust from adjacent deserts) would be the possible reason for poor representation of dust AOD and in turn total AOD over Indian region in CMIP5 models. In addition, aerosol radiative forcing (ARF) underestimated/overestimated in most of the models. However, spatial distribution of ARF in multi-model ensemble mean is comparable reasonably well with observations with bias in magnitudes. This analysis emphasizes the fundamental need to improve the representation of aerosol species in current state of the art climate models. As reported in Intergovernmental Panel on Climate Change (IPCC) fourth assessment report (AR4), the level of scientific understanding (LOSU) of climatic impact of aerosols is medium-low. For better understanding of

  16. Evaluation of Aerosol-cloud Interaction in the GISS Model E Using ARM Observations

    NASA Technical Reports Server (NTRS)

    DeBoer, G.; Bauer, S. E.; Toto, T.; Menon, Surabi; Vogelmann, A. M.

    2013-01-01

    Observations from the US Department of Energy's Atmospheric Radiation Measurement (ARM) program are used to evaluate the ability of the NASA GISS ModelE global climate model in reproducing observed interactions between aerosols and clouds. Included in the evaluation are comparisons of basic meteorology and aerosol properties, droplet activation, effective radius parameterizations, and surface-based evaluations of aerosol-cloud interactions (ACI). Differences between the simulated and observed ACI are generally large, but these differences may result partially from vertical distribution of aerosol in the model, rather than the representation of physical processes governing the interactions between aerosols and clouds. Compared to the current observations, the ModelE often features elevated droplet concentrations for a given aerosol concentration, indicating that the activation parameterizations used may be too aggressive. Additionally, parameterizations for effective radius commonly used in models were tested using ARM observations, and there was no clear superior parameterization for the cases reviewed here. This lack of consensus is demonstrated to result in potentially large, statistically significant differences to surface radiative budgets, should one parameterization be chosen over another.

  17. Aerosol Simulation in the Mexico City Metropolitan Area during MCMA2003 using CMAQ/Models3

    NASA Astrophysics Data System (ADS)

    Bei, N.; Zavala, M.; Lei, W.; de Foy, B.; Molina, L.

    2007-12-01

    CMAQ/Models3 has been employed to simulate the aerosol distribution and variation during the period from 13 to 16 April 2003 over the Mexico City Metropolitan Area as part of MCMA-2003 campaign. The meteorological fields are simulated using MM5, with three one-way nested grids with horizontal resolutions of 36, 12 and 3 km and 23 sigma levels in the vertical. MM5 3DVAR system has also been incorporated into the meteorological simulations. Chemical initial and boundary conditions are interpolated from the MOZART output. The SAPRC emission inventory is developed based on the official emission inventory for MCMA in 2004. The simulated mass concentrations of different aerosol compositions, such as elemental carbon (EC), primary organic aerosol (POA), secondary organic aerosol (SOA), nitrate, ammonium, and sulfate have been compared to the measurements taken at the National Center for Environmental Research and Training (Centro Nacional de Investigacion y Capacitacion Ambiental, CENICA) super-site. Hydrocarbon-like organic aerosol (HOA) and oxygenated organic aerosol (OOA) are used as observations of POA and SOA, respectively in this study. The preliminary model results show that the temporal evolutions of EC and POA are reasonable compared with measurements. The peak time of EC and POA are basically reproduced, thus validating the emission inventory and its processing through CMAQ/Models3. But the magnitude of EC and POA are underestimated over the entire episode. The modeled nitrate and ammonium concentrations are overestimated on most of the days. There is 1-2 hour difference between the simulated peak time of nitrate and ammonium aerosols compared to observations at CENICA. The simulated mass concentrations of SOA and sulfate are significantly underestimated. The reasons of the discrepancy between simulations and measurements are due to the uncertainties existing in the emission inventory, meteorological fields, and as well as aerosol formation mechanism in the case

  18. Development of a model for characterizing pneumatically generated primary aerosols for inductively coupled plasma emission spectrometry

    SciTech Connect

    Msimanga, N.D.G.

    1992-01-01

    The study of aerosols plays a key role in the development of analytical atomic spectroscopy. While work has been carried out with Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) to improve transport efficiency, analyte signal, limits of detection, and to reduce matrix interferences, little study has focused on sample introduction processes. This study has focused on the characterization and optimization of pneumatic nebulizers used for liquid sample introduction to the ICP. Pneumatic nebulization is the most common means of sample introduction in atomic spectrometry. The pneumatic nebulizers most commonly used today for ICP spectrometry are the cross-flow type or all-glass concentric nebulizers. Aerosols undergo certain processes after the primary formation process before reaching the atomizer, the secondary and tertiary stages. In this work all three stages were looked at, focusing on the primary aerosols. The primary aerosol is the first stage in the formation of the aerosols and takes place at the tip of the nebulizer, as the liquid stream is shattered by the gas flow. The drop size diameters of primary aerosols were measured using a Fraunhofer Laser Diffraction instrument. The Sauter mean diameter (D3.2), which describes the volume of the aerosol with a given surface area, was determined for nebulizers at spray chambers operated under a variety of conditions. The characterization and optimization of sample introduction involved a study of aerosol technology, a study of different instruments for measuring the mean drop size, a description of the instrument, and the influence of some parameters on the D3.2. An empirical model summarizing the characteristics of the primary aerosols is proposed. Modeling is carried out using nonlinear software. The data for modelling were acquired using water, n-butanol, and methanol as the liquid solvents. The model was tested on data obtained from nebulizers with different cross-sectional areas.

  19. A Study of Cloud Processing of Organic Aerosols Using Models and CHAPS Data

    SciTech Connect

    Ervens, Barbara

    2012-01-17

    The main theme of our work has been the identification of parameters that mostly affect the formation and modification of aerosol particles and their interaction with water vapor. Our detailed process model studies led to simplifications/parameterizations of these effects that bridge detailed aerosol information from laboratory and field studies and the need for computationally efficient expressions in complex atmospheric models. One focus of our studies has been organic aerosol mass that is formed in the atmosphere by physical and/or chemical processes (secondary organic aerosol, SOA) and represents a large fraction of atmospheric particulate matter. Most current models only describe SOA formation by condensation of low volatility (or semivolatile) gas phase products and neglect processes in the aqueous phase of particles or cloud droplets that differently affect aerosol size and vertical distribution and chemical composition (hygroscopicity). We developed and applied models of aqueous phase SOA formation in cloud droplets and aerosol particles (aqSOA). Placing our model results into the context of laboratory, model and field studies suggests a potentially significant contribution of aqSOA to the global organic mass loading. The second focus of our work has been the analysis of ambient data of particles that might act as cloud condensation nuclei (CCN) at different locations and emission scenarios. Our model studies showed that the description of particle chemical composition and mixing state can often be greatly simplified, in particular in aged aerosol. While over the past years many CCN studies have been successful performed by using such simplified composition/mixing state assumptions, much more uncertainty exists in aerosol-cloud interactions in cold clouds (ice or mixed-phase). Therefore we extended our parcel model that describes warm cloud formation by ice microphysics and explored microphysical parameters that determine the phase state and lifetime of

  20. Aerosol cluster impact and break-up : II. Atomic and Cluster Scale Models.

    SciTech Connect

    Lechman, Jeremy B.; Takato, Yoichi

    2010-09-01

    Understanding the interaction of aerosol particle clusters/flocs with surfaces is an area of interest for a number of processes in chemical, pharmaceutical, and powder manufacturing as well as in steam-tube rupture in nuclear power plants. Developing predictive capabilities for these applications involves coupled phenomena on multiple length and timescales from the process macroscopic scale ({approx}1m) to the multi-cluster interaction scale (1mm-0.1m) to the single cluster scale ({approx}1000 - 10000 particles) to the particle scale (10nm-10{micro}m) interactions, and on down to the sub-particle, atomic scale interactions. The focus of this report is on the single cluster scale; although work directed toward developing better models of particle-particle interactions by considering sub-particle scale interactions and phenomena is also described. In particular, results of mesoscale (i.e., particle to single cluster scale) discrete element method (DEM) simulations for aerosol cluster impact with rigid walls are presented. The particle-particle interaction model is based on JKR adhesion theory and is implemented as an enhancement to the granular package in the LAMMPS code. The theory behind the model is outlined and preliminary results are shown. Additionally, as mentioned, results from atomistic classical molecular dynamics simulations are also described as a means of developing higher fidelity models of particle-particle interactions. Ultimately, the results from these and other studies at various scales must be collated to provide systems level models with accurate 'sub-grid' information for design, analysis and control of the underlying systems processes.

  1. LES of Laminar-to-Turbulent Particle-Fluid Dynamics in Human and Nonhuman Primate Airways: Applications to Aerosolized Drug Delivery Animal Testing

    NASA Astrophysics Data System (ADS)

    Geisler, Taylor; Padhy, Sourav; Shaqfeh, Eric; Iaccarino, Gianluca

    2016-11-01

    Both the human health benefit and risk from the inhalation of aerosolized medications is often predicted by extrapolating experimental data taken using nonhuman primates to human inhalation. In this study, we employ Large Eddy Simulation to simulate particle-fluid dynamics in realistic upper airway models of both humans and rhesus monkeys. We report laminar-to-turbulent flow transitions triggered by constrictions in the upper trachea and the persistence of unsteadiness into the low Reynolds number bifurcating lower airway. Micro-particle deposition fraction and locations are shown to depend significantly on particle size. In particular, particle filtration in the nasal airways is shown to approach unity for large aerosols (8 microns) or high-rate breathing. We validate the accuracy of LES mean flow predictions using MRV imaging results. Additionally, particle deposition fractions are validated against experiments in 3 model airways.

  2. Aerosol dynamics using the quadrature method of moments: comparing several quadrature schemes with particle-resolved simulation

    NASA Astrophysics Data System (ADS)

    McGraw, R.; Leng, L.; Zhu, W.; Riemer, N.; West, M.

    2008-07-01

    The method of moments (MOM) is a statistically based alternative to sectional and modal methods for aerosol simulation. The MOM is highly efficient as the aerosol distribution is represented by its lower-order moments and only these, not the full distribution itself, are tracked during simulation. Quadrature is introduced to close the moment equations under very general growth laws and to compute aerosol physical and optical properties directly from moments. In this paper the quadrature method of moments (QMOM) is used in a bivariate test tracking of aerosol mixing state. Two aerosol populations, one enriched in soot and the other in sulfate, are allowed to interact through coagulation to form a generally-mixed third particle population. Quadratures of varying complexity (including two candidate schemes for use in climate models) are described and compared with benchmark results obtained by using particle-resolved simulation. Low-order quadratures are found to be highly accurate, and Gauss and Gauss-Radau quadratures appear to give nested lower and upper bounds, respectively, to aerosol mixing rate. These results suggest that the QMOM makes it feasible to represent the generallymixed states of aerosols and track their evolution in climate models.

  3. Why Is Improvement of Earth System Models So Elusive? Challenges and Strategies From Dust Aerosol Modeling

    NASA Astrophysics Data System (ADS)

    Miller, R. L.; Pérez García-Pando, C.; Perlwitz, J. P.; Ginoux, P. A.

    2015-12-01

    Past decades have seen an accelerating increase in computing efficiency,while climate models are representing a rapidly widening set ofphysical processes. Yet simulations of some fundamental aspects ofclimate like precipitation or aerosol forcing remain highly uncertainand resistent to progress. Dust aerosol modeling of soil particleslofted by wind erosion has seen a similar conflict between increasingmodel sophistication and remaining uncertainty. Dust aerosols perturbthe energy and water cycles by scattering radiation and acting as icenuclei, while mediating atmospheric chemistry and marinephotosynthesis (and thus the carbon cycle). These effects take placeacross scales from the dimensions of an ice crystal to theplanetary-scale circulation that disperses dust far downwind of itsparent soil. Representing this range leads to several modelingchallenges. Should we limit complexity in our model, which consumescomputer resources and inhibits interpretation? How do we decide if aprocess involving dust is worthy of inclusion within our model? Canwe identify a minimal representation of a complex process that isefficient yet retains the physics relevant to climate? Answeringthese questions about the appropriate degree of representation isguided by model evaluation, which presents several more challenges.How do we proceed if the available observations do not directlyconstrain our process of interest? (This could result from competingprocesses that influence the observed variable and obscure thesignature of our process of interest.) Examples will be presentedfrom dust modeling, with lessons that might be more broadlyapplicable. The end result will either be clinical depression or thereassuring promise of continued gainful employment as the communityconfronts these challenges.

  4. A modeling study of the effects of aerosols on clouds and precipitation over East Asia

    NASA Astrophysics Data System (ADS)

    Liu, Xiaodong; Xie, Xiaoning; Yin, Zhi-Yong; Liu, Changhai; Gettelman, Andrew

    2011-12-01

    The National Center for Atmospheric Research Community Atmosphere Model (version 3.5) coupled with the Morrison-Gettelman two-moment cloud microphysics scheme is employed to simulate the aerosol effects on clouds and precipitation in two numerical experiments, one representing present-day conditions (year 2000) and the other the pre-industrial conditions (year 1750) over East Asia by considering both direct and indirect aerosol effects. To isolate the aerosol effects, we used the same set of boundary conditions and only altered the aerosol emissions in both experiments. The simulated results show that the cloud microphysical properties are markedly affected by the increase in aerosols, especially for the column cloud droplet number concentration (DNC), liquid water path (LWP), and the cloud droplet effective radius (DER). With increased aerosols, DNC and LWP have been increased by 137% and 28%, respectively, while DER is reduced by 20%. Precipitation rates in East Asia and East China are reduced by 5.8% and 13%, respectively, by both the aerosol's second indirect effect and the radiative forcing that enhanced atmospheric stability associated with the aerosol direct and first indirect effects. The significant reduction in summer precipitation in East Asia is also consistent with the weakening of the East Asian summer monsoon, resulting from the decreasing thermodynamic contrast between the Asian landmass and the surrounding oceans induced by the aerosol's radiative effects. The increase in aerosols reduces the surface net shortwave radiative flux over the East Asia landmass, which leads to the reduction of the land surface temperature. With minimal changes in the sea surface temperature, hence, the weakening of the East Asian summer monsoon further enhances the reduction of summer precipitation over East Asia.

  5. The Role of Atmospheric Aerosol Concentration on Deep Convective Precipitation: Cloud-resolving Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Li, X.; Khain, A.; Mastsui, T.; Lang, S.; Simpson, J.

    2007-01-01

    Aerosols and especially their effect on clouds are one of the key components of the climate system and the hydrological cycle [Ramanathan et al., 20011. Yet, the aerosol effect on clouds remains largely unknown and the processes involved not well understood. A recent report published by the National Academy of Science states "The greatest uncertainty about the aerosol climate forcing - indeed, the largest of all the uncertainties about global climate forcing - is probably the indirect effect of aerosols on clouds NRC [2001]." The aerosol effect on clouds is often categorized into the traditional "first indirect (i.e., Twomey)" effect on the cloud droplet sizes for a constant liquid water path and the "semi-direct" effect on cloud coverage. The aerosol effect on precipitation processes, also known as the second type of aerosol indirect effect, is even more complex, especially for mixed-phase convective clouds. ln this paper, a cloud-resolving model (CRM) with detailed spectral-bin microphysics was used to examine the effect of aerosols on three different deep convective cloud systems that developed in different geographic locations: South Florida, Oklahoma and the Central Pacific. In all three cases, rain reaches the ground earlier for the low CCN (clean) case. Rain suppression is also evident in all three cases with high CCN (dirty) case. However, this suppression only occurs during the first hour of the simulations. During the mature stages of the simulations, the effects of increasing aerosol concentration range from rain suppression in the Oklahoma case, to almost no effect in the Florida case, to rain enhancement in the Pacific case. These results show the complexity of aerosol interactions with convection.

  6. A global modeling study on carbonaceous aerosol microphysical characteristics and radiative effects

    NASA Astrophysics Data System (ADS)

    Bauer, S. E.; Menon, S.; Koch, D.; Bond, T. C.; Tsigaridis, K.

    2010-08-01

    Recently, attention has been drawn towards black carbon aerosols as a short-term climate warming mitigation candidate. However the global and regional impacts of the direct, indirect and semi-direct aerosol effects are highly uncertain, due to the complex nature of aerosol evolution and the way that mixed, aged aerosols interact with clouds and radiation. A detailed aerosol microphysical scheme, MATRIX, embedded within the GISS climate model is used in this study to present a quantitative assessment of the impact of microphysical processes involving black carbon, such as emission size distributions and optical properties on aerosol cloud activation and radiative effects. Our best estimate for net direct and indirect aerosol radiative flux change between 1750 and 2000 is -0.56 W/m2. However, the direct and indirect aerosol effects are quite sensitive to the black and organic carbon size distribution and consequential mixing state. The net radiative flux change can vary between -0.32 to -0.75 W/m2 depending on these carbonaceous particle properties at emission. Taking into account internally mixed black carbon particles let us simulate correct aerosol absorption. Absorption of black carbon aerosols is amplified by sulfate and nitrate coatings and, even more strongly, by organic coatings. Black carbon mitigation scenarios generally showed reduced radiative fluxeswhen sources with a large proportion of black carbon, such as diesel, are reduced; however reducing sources with a larger organic carbon component as well, such as bio-fuels, does not necessarily lead to a reduction in positive radiative flux.

  7. A Global Modeling Study on Carbonaceous Aerosol Microphysical Characteristics and Radiative Effects

    NASA Technical Reports Server (NTRS)

    Bauer, S. E.; Menon, S.; Koch, D.; Bond, T. C.; Tsigaridis, K.

    2010-01-01

    Recently, attention has been drawn towards black carbon aerosols as a short-term climate warming mitigation candidate. However the global and regional impacts of the direct, indirect and semi-direct aerosol effects are highly uncertain, due to the complex nature of aerosol evolution and the way that mixed, aged aerosols interact with clouds and radiation. A detailed aerosol microphysical scheme, MATRIX, embedded within the GISS climate model is used in this study to present a quantitative assessment of the impact of microphysical processes involving black carbon, such as emission size distributions and optical properties on aerosol cloud activation and radiative effects. Our best estimate for net direct and indirect aerosol radiative flux change between 1750 and 2000 is -0.56 W/m2. However, the direct and indirect aerosol effects are quite sensitive to the black and organic carbon size distribution and consequential mixing state. The net radiative flux change can vary between -0.32 to -0.75 W/m2 depending on these carbonaceous particle properties at emission. Taking into account internally mixed black carbon particles let us simulate correct aerosol absorption. Absorption of black carbon aerosols is amplified by sulfate and nitrate coatings and, even more strongly, by organic coatings. Black carbon mitigation scenarios generally showed reduced radiative fluxeswhen sources with a large proportion of black carbon, such as diesel, are reduced; however reducing sources with a larger organic carbon component as well, such as bio-fuels, does not necessarily lead to a reduction in positive radiative flux.

  8. A model for the separation of cloud and aerosol in SAGE II occultation data

    NASA Technical Reports Server (NTRS)

    Kent, G. S.; Winker, D. M.; Osborn, M. T.; Skeens, K. M.

    1993-01-01

    The Stratospheric Aerosol and Gas Experiment (SAGE) II satellite experiment measures the extinction due to aerosols and thin cloud, at wavelengths of 0.525 and 1.02 micrometers, down to an altitude of 6 km. The wavelength dependence of the extinction due to aerosols differs from that of the extinction due to cloud and is used as the basis of a model for separating these two components. The model is presented and its validation using airborne lidar data, obtained coincident with SAGE II observations, is described. This comparison shows that smaller SAGE II cloud extinction values correspond to the presence of subvisible cirrus cloud in the lidar record. Examples of aerosol and cloud data products obtained using this model to interpret SAGE II upper tropospheric and lower stratospheric data are also shown.

  9. Model simulations of the first aerosol indirect effect and comparison of cloud susceptibility fo satellite measurements

    SciTech Connect

    Chuang, C; Penner, J E; Kawamoto, K

    2002-03-08

    Present-day global anthropogenic emissions contribute more than half of the mass in submicron particles primarily due to sulfate and carbonaceous aerosol components derived from fossil fuel combustion and biomass burning. These anthropogenic aerosols modify the microphysics of clouds by serving as cloud condensation nuclei (CCN) and enhance the reflectivity of low-level water clouds, leading to a cooling effect on climate (the Twomey effect or first indirect effect). The magnitude of the first aerosol indirect effect is associated with cloud frequency as well as a quantity representing the sensitivity of cloud albedo to changes in cloud drop number concentration. This quantity is referred to as cloud susceptibility [Twomey, 1991]. Analysis of satellite measurements demonstrates that marine stratus clouds are likely to be of higher susceptibility than continental clouds because of their lower number concentrations of cloud drops [Platnick and Twomey, 1994]. Here, we use an improved version of the fully coupled climate/chemistry model [Chuang et al., 1997] to calculate the global concentrations Of sulfate, dust, sea salt, and carbonaceous aerosols (biomass smoke and fossil fuel organic matter and black carbon). We investigated the impact of anthropogenic aerosols on cloud susceptibility and calculated the associated changes of shortwave radiative fluxes at the top of the atmosphere. We also examined the correspondence between the model simulation of cloud susceptibility and that inferred from satellite measurements to test whether our simulated aerosol concentrations and aerosol/cloud interactions give a faithful representation of these features.

  10. Nanosized aerosols from consumer sprays: experimental analysis and exposure modeling for four commercial products

    NASA Astrophysics Data System (ADS)

    Lorenz, Christiane; Hagendorfer, Harald; von Goetz, Natalie; Kaegi, Ralf; Gehrig, Robert; Ulrich, Andrea; Scheringer, Martin; Hungerbühler, Konrad

    2011-08-01

    Consumer spray products are already on the market in the cosmetics and household sector, which suggest by their label that they contain engineered nanoparticles (ENP). Sprays are considered critical for human health, because the lungs represent a major route for the uptake of ENP into the human body. To contribute to the exposure assessment of ENP in consumer spray products, we analyzed ENP in four commercially available sprays: one antiperspirant, two shoe impregnation sprays, and one plant-strengthening agent. The spray dispersions were analyzed by inductively coupled plasma mass spectrometry (ICPMS) and (scanning-) transmission electron microscopy ((S)TEM). Aerosols were generated by using the original vessels, and analyzed by scanning mobility particle sizer (SMPS) and (S)TEM. On the basis of SMPS results, the nanosized aerosol depositing in the respiratory tract was modeled for female and male consumers. The derived exposure levels reflect a single spray application. We identified ENP in the dispersions of two products (shoe impregnation and plant spray). Nanosized aerosols were observed in three products that contained propellant gas. The aerosol number concentration increased linearly with the sprayed amount, with the highest concentration resulting from the antiperspirant. Modeled aerosol exposure levels were in the range of 1010 nanosized aerosol components per person and application event for the antiperspirant and the impregnation sprays, with the largest fraction of nanosized aerosol depositing in the alveolar region. Negligible exposure from the application of the plant spray (pump spray) was observed.

  11. Biology of the Coarse Aerosol Mode: Insights Into Urban Aerosol Ecology

    NASA Astrophysics Data System (ADS)

    Dueker, E.; O'Mullan, G. D.; Montero, A.

    2015-12-01

    Microbial aerosols have been understudied, despite implications for climate studies, public health, and biogeochemical cycling. Because viable bacterial aerosols are often associated with coarse aerosol particles, our limited understanding of the coarse aerosol mode further impedes our ability to develop models of viable bacterial aerosol production, transport, and fate in the outdoor environment, particularly in crowded urban centers. To address this knowledge gap, we studied aerosol particle biology and size distributions in a broad range of urban and rural settings. Our previously published findings suggest a link between microbial viability and local production of coarse aerosols from waterways, waste treatment facilities, and terrestrial systems in urban and rural environments. Both in coastal Maine and in New York Harbor, coarse aerosols and viable bacterial aerosols increased with increasing wind speeds above 4 m s-1, a dynamic that was observed over time scales ranging from minutes to hours. At a New York City superfund-designated waterway regularly contaminated with raw sewage, aeration remediation efforts resulted in significant increases of coarse aerosols and bacterial aerosols above that waterway. Our current research indicates that bacterial communities in aerosols at this superfund site have a greater similarity to bacterial communities in the contaminated waterway with wind speeds above 4 m s-1. Size-fractionated sampling of viable microbial aerosols along the urban waterfront has also revealed significant shifts in bacterial aerosols, and specifically bacteria associated with coarse aerosols, when wind direction changes from onshore to offshore. This research highlights the key connections between bacterial aerosol viability and the coarse aerosol fraction, which is important in assessments of production, transport, and fate of bacterial contamination in the urban environment.

  12. Aerosol indirect effects -- general circulation model intercomparison and evaluation with satellite data

    SciTech Connect

    Quaas, Johannes; Ming, Yi; Menon, Surabi; Takemura, Toshihiko; Wang, Minghuai; Penner, Joyce E.; Gettelman, Andrew; Lohmann, Ulrike; Bellouin, Nicolas; Boucher, Olivier; Sayer, Andrew M.; Thomas, Gareth E.; McComiskey, Allison; Feingold, Graham; Hoose, Corinna; Kristjansson, Jon Egill; Liu, Xiaohong; Balkanski, Yves; Donner, Leo J.; Ginoux, Paul A.; Stier, Philip; Feichter, Johann; Sednev, Igor; Bauer, Susanne E.; Koch, Dorothy; Grainger, Roy G.; Kirkevag, Alf; Iversen, Trond; Seland, Oyvind; Easter, Richard; Ghan, Steven J.; Rasch, Philip J.; Morrison, Hugh; Lamarque, Jean-Francois; Iacono, Michael J.; Kinne, Stefan; Schulz, Michael

    2009-04-10

    Aerosol indirect effects continue to constitute one of the most important uncertainties for anthropogenic climate perturbations. Within the international AEROCOM initiative, the representation of aerosol-cloud-radiation interactions in ten different general circulation models (GCMs) is evaluated using three satellite datasets. The focus is on stratiform liquid water clouds since most GCMs do not include ice nucleation effects, and none of the model explicitly parameterizes aerosol effects on convective clouds. We compute statistical relationships between aerosol optical depth (Ta) and various cloud and radiation quantities in a manner that is consistent between the models and the satellite data. It is found that the model-simulated influence of aerosols on cloud droplet number concentration (Nd) compares relatively well to the satellite data at least over the ocean. The relationship between Ta and liquid water path is simulated much too strongly by the models. It is shown that this is partly related to the representation of the second aerosol indirect effect in terms of autoconversion. A positive relationship between total cloud fraction (fcld) and Ta as found in the satellite data is simulated by the majority of the models, albeit less strongly than that in the satellite data in most of them. In a discussion of the hypotheses proposed in the literature to explain the satellite-derived strong fcld - Ta relationship, our results indicate that none can be identified as unique explanation. Relationships similar to the ones found in satellite data between Ta and cloud top temperature or outgoing long-wave radiation (OLR) are simulated by only a few GCMs. The GCMs that simulate a negative OLR - Ta relationship show a strong positive correlation between Ta and fcld The short-wave total aerosol radiative forcing as simulated by the GCMs is strongly influenced by the simulated anthropogenic fraction of Ta, and parameterisation assumptions such as a lower bound on Nd

  13. Development of an in vitro cytotoxicity model for aerosol exposure using 3D reconstructed human airway tissue; application for assessment of e-cigarette aerosol.

    PubMed

    Neilson, Louise; Mankus, Courtney; Thorne, David; Jackson, George; DeBay, Jason; Meredith, Clive

    2015-10-01

    Development of physiologically relevant test methods to analyse potential irritant effects to the respiratory tract caused by e-cigarette aerosols is required. This paper reports the method development and optimisation of an acute in vitro MTT cytotoxicity assay using human 3D reconstructed airway tissues and an aerosol exposure system. The EpiAirway™ tissue is a highly differentiated in vitro human airway culture derived from primary human tracheal/bronchial epithelial cells grown at the air-liquid interface, which can be exposed to aerosols generated by the VITROCELL® smoking robot. Method development was supported by understanding the compatibility of these tissues within the VITROCELL® system, in terms of airflow (L/min), vacuum rate (mL/min) and exposure time. Dosimetry tools (QCM) were used to measure deposited mass, to confirm the provision of e-cigarette aerosol to the tissues. EpiAirway™ tissues were exposed to cigarette smoke and aerosol generated from two commercial e-cigarettes for up to 6 h. Cigarette smoke reduced cell viability in a time dependent manner to 12% at 6 h. E-cigarette aerosol showed no such decrease in cell viability and displayed similar results to that of the untreated air controls. Applicability of the EpiAirway™ model and exposure system was demonstrated, showing little cytotoxicity from e-cigarette aerosol and different aerosol formulations when compared directly with reference cigarette smoke, over the same exposure time.

  14. Role of Clouds, Aerosols, and Aerosol-Cloud Interaction in 20th Century Simulations with GISS ModelE2

    NASA Technical Reports Server (NTRS)

    Nazarenko, Larissa; Rind, David; Bauer, Susanne; Del Genio, Anthony

    2015-01-01

    The key uncertainties in the climate sensitivity to the increasing greenhouse gases lie in the behavior and impact of short-lived species, such as tropospheric