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Sample records for aerosol microphysical processes

  1. Microphysical processing of aerosol particles in orographic clouds

    NASA Astrophysics Data System (ADS)

    Pousse-Nottelmann, S.; Zubler, E. M.; Lohmann, U.

    2015-01-01

    An explicit and detailed treatment of cloud-borne particles allowing for the consideration of aerosol cycling in clouds has been implemented in the regional weather forecast and climate model COSMO. The effects of aerosol scavenging, cloud microphysical processing and regeneration upon cloud evaporation on the aerosol population and on subsequent cloud formation are investigated. For this, two-dimensional idealized simulations of moist flow over two bell-shaped mountains were carried out varying the treatment of aerosol scavenging and regeneration processes for a warm-phase and a mixed-phase orographic cloud. The results allowed to identify different aerosol cycling mechanisms. In the simulated non-precipitating warm-phase cloud, aerosol mass is incorporated into cloud droplets by activation scavenging and released back to the atmosphere upon cloud droplet evaporation. In the mixed-phase cloud, a first cycle comprises cloud droplet activation and evaporation via the Wegener-Bergeron-Findeisen process. A second cycle includes below-cloud scavenging by precipitating snow particles and snow sublimation and is connected to the first cycle via the riming process which transfers aerosol mass from cloud droplets to snow flakes. In the simulated mixed-phase cloud, only a negligible part of the total aerosol mass is incorporated into ice crystals. Sedimenting snow flakes reaching the surface remove aerosol mass from the atmosphere. The results show that aerosol processing and regeneration lead to a vertical redistribution of aerosol mass and number. However, the processes not only impact the total aerosol number and mass, but also the shape of the aerosol size distributions by enhancing the internally mixed/soluble accumulation mode and generating coarse mode particles. Concerning subsequent cloud formation at the second mountain, accounting for aerosol processing and regeneration increases the cloud droplet number concentration with possible implications for the ice

  2. Microphysical processing of aerosol particles in orographic clouds

    NASA Astrophysics Data System (ADS)

    Pousse-Nottelmann, S.; Zubler, E. M.; Lohmann, U.

    2015-08-01

    An explicit and detailed treatment of cloud-borne particles allowing for the consideration of aerosol cycling in clouds has been implemented into COSMO-Model, the regional weather forecast and climate model of the Consortium for Small-scale Modeling (COSMO). The effects of aerosol scavenging, cloud microphysical processing and regeneration upon cloud evaporation on the aerosol population and on subsequent cloud formation are investigated. For this, two-dimensional idealized simulations of moist flow over two bell-shaped mountains were carried out varying the treatment of aerosol scavenging and regeneration processes for a warm-phase and a mixed-phase orographic cloud. The results allowed us to identify different aerosol cycling mechanisms. In the simulated non-precipitating warm-phase cloud, aerosol mass is incorporated into cloud droplets by activation scavenging and released back to the atmosphere upon cloud droplet evaporation. In the mixed-phase cloud, a first cycle comprises cloud droplet activation and evaporation via the Wegener-Bergeron-Findeisen (WBF) process. A second cycle includes below-cloud scavenging by precipitating snow particles and snow sublimation and is connected to the first cycle via the riming process which transfers aerosol mass from cloud droplets to snowflakes. In the simulated mixed-phase cloud, only a negligible part of the total aerosol mass is incorporated into ice crystals. Sedimenting snowflakes reaching the surface remove aerosol mass from the atmosphere. The results show that aerosol processing and regeneration lead to a vertical redistribution of aerosol mass and number. Thereby, the processes impact the total aerosol number and mass and additionally alter the shape of the aerosol size distributions by enhancing the internally mixed/soluble Aitken and accumulation mode and generating coarse-mode particles. Concerning subsequent cloud formation at the second mountain, accounting for aerosol processing and regeneration increases

  3. Aerosol microphysical processes and properties in Canadian boreal forest fire plumes measured during BORTAS

    NASA Astrophysics Data System (ADS)

    Sakamoto, Kimiko; Allen, James; Coe, Hugh; Taylor, Jonathan; Duck, Thomas; Pierce, Jeffrey

    2013-04-01

    Biomass burning emissions contribute significantly to aerosol concentrations and clound condensation nuclei in many regions of the atmosphere. Plume-aerosol characteristics vary according to age, fuel type, and region. These differences are poorly represented in regional and global aerosol models, and they contribute to large uncertainties in predicted size distributions in biomass-burning-dominated regions. The Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS) measurement campaign was designed to invesigate boreal biomass burning emissions over Atlantic Canada during July-August of 2011. Aged (2-3 days) biomass burning aerosols originating from western Ontario were measured by an SMPS and AMS on board the British Atmospheric Research Aircraft. We identify the presence of plumes using CO concentrations and acetonitrile enhancement ratios. In-plume aerosol size distributions were collected for six aged plume profiles. The size distributions show an accumulation-mode median diameter of ~240 nm. However, there are persistant nucleation and Aitken modes present in the profiles, even 2-3 days from the source. Without continuous nucleation and condensation (likely SOA production), these small modes would be lost by coagulation in less than 1 day. We use an aerosol microphysics plume model to estimate the mean nucleation and condensation rates necessary to maintain the small aerosols, and calculate how these processes enhance the total number of particles and cloud condensation nuclei in the aged plume.

  4. Unified Aerosol Microphysics for NWP

    DTIC Science & Technology

    2012-09-30

    prediction is now integrated, for example, with the COAMPS two- moment cloud microphysics scheme where it serves as a source of cloud droplet nuclei. The dust ...behavior. To evaluate the new handling of aerosol dust and its interaction with COAMPS microphysics, an operational test case has been developed...Sahara Air Layer (SAL) and Hurricane Nadine off of West Africa. Dust is seen wrapping around the north side of the storm on Sep 11 in Figure 2. We

  5. Unified Aerosol Microphysics for NWP

    DTIC Science & Technology

    2013-09-30

    observations during an Algerian dust storm with the 12-hour forecast from COAMPS , valid at 12GMT March 3, 2013. Left: MSG visible image (black and white...nuclei in the COAMPS two-moment cloud microphysics scheme. The dust and cloud microphysical processes are fully interactive in that the cloud...and satellite data show that COAMPS has captured this event. The dust plume is accurately aligned with the observed dust event. COAMPS forecasts

  6. Reformulating Aerosol Thermodynamics and Cloud Microphysics

    NASA Astrophysics Data System (ADS)

    Metzger, S.

    2006-12-01

    Modeling aerosol composition and cloud microphysics is rather complex due to the required thermodynamics, even if chemical and thermodynamical equilibrium is assumed. We show, however, that for deliquescent atmospheric aerosols thermodynamics can be considerably simplified, if we reformulate chemical equilibrium to include water purely based on thermodynamic principles. In chemical and thermodynamical equilibrium, the relative humidity (RH) fixes the molality of atmospheric aerosols. Although this fact is in theory well known, it has hardly been utilized in aerosol modeling nor has been the fact that for the same reason also the aerosol activity (including activity coefficients) and water content are fixed (by RH) for a given aerosol concentration and type. The only model that successfully utilizes this fact is the computationally very efficient EQuilibrium Simplified thermodynamic gas/Aerosol partitioning Model, EQSAM (Metzger et al., 2002a), EQSAM2 (Metzger et al., 2006). In both versions the entire gas/liquid/solid aerosol equilibrium partitioning is solved analytically and hence non-iteratively a substantial advantage in aerosol composition modeling. Here we briefly present the theoretical framework of EQSAM2, which differs from EQSAM in a way that the calculation of the water activity of saturated binary or mixed inorganic/organic salt solutions of multi-component aerosols has been generalized by including the Kelvin-term, thus allowing for any solute activity above the deliquescence relative humidity, including supersaturation. With application of our new concept to a numerical whether prediction (NWP) model, we demonstrate its wide implications for the computation of various aerosol and cloud properties, as our new concept allows to consistently and efficiently link the modeling of aerosol thermodynamics and cloud microphysics through the aerosol water mass, which therefore deserves special attention in atmospheric chemistry, air pollution, NWP and climate

  7. Unified Aerosol Microphysics for NWP

    DTIC Science & Technology

    2011-09-30

    Specifically, the goal is to develop a COAMPS that is capable of simulating the full range of interactions between aerosol particles, clouds , and radiative...aerosol species that are responsible for degradation of Electro- Optical (EO) propagation or that modify cloud behavior and lifetime. Report...enabling new development of more complex cloud -aerosol interactions. The work on this project has been divided into two phases, an investigation phase

  8. Aerosol Microphysics and Radiation Integration

    DTIC Science & Technology

    2016-06-13

    storm activity, and 4) surface and airborne measurements on the west coast of the U.S. indicate the presence of aerosols and dust on the predicted...observables (in situ and satellites) and model quantities such as mass. Aerosol species currently included in the analyses are dust , pollution, biomass...Prediction System ( COAMPS ®). Over the next several years it is the goal of this project to maintain these systems as the world leaders in EO prediction

  9. Aerosol Microphysics and Radiation Integration

    DTIC Science & Technology

    2016-06-07

    for dust storm forecasting and analysis, AGU Fall Meeting, San Francisco, CA. Dec. 11-15, 2002 [Published]. Reid, J.S., J.R. Cook, D.L. Westphal...Persian Gulf/Arabian Sea, East Asia, and some parts of the Mediterranean Sea. Along coastal regions, dust , pollution and smoke can be present and...transitioned from the combined Marine Aerosol and Dust Aerosol programs from SPAWAR Systems Center San Diego (SSC-SD) to the Naval Research Laboratory

  10. 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 nmmicrophysics can be represented explicitly with aerosol 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

  11. Aerosol Microphysics and Radiation Integration

    DTIC Science & Technology

    2005-09-30

    from the massive dust storm that occurred at the start of Operation Iraqi Freedom in late March 2003, may have been sampled during ADAM. COAMPS ...Along coastal and even some deep ocean regions, dust , pollution and smoke are often present and can dominate Electro-Optical (EO) effects over... COAMPS ®1) and the NRL Aerosol Analysis and Prediction System (NAAPS) require precise source and sink functions, as well as parameterizations for particle

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Parameterizations of Cloud Microphysics and Indirect Aerosol Effects

    SciTech Connect

    Tao, Wei-Kuo

    2014-05-19

    1. OVERVIEW 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., 2000]. 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, 1999]. 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

  17. High resolution WRF simulations of Hurricane Irene: Sensitivity to aerosols and choice of microphysical schemes

    NASA Astrophysics Data System (ADS)

    Khain, A.; Lynn, B.; Shpund, J.

    2016-01-01

    Recent studies have pointed to the possible sensitivity of hurricanes to aerosols via aerosol effects on microphysical and thermodynamic processes in clouds. Hurricane Irene, occurring in August 2011, is an excellent case study for investigating aerosol effects on tropical cyclone (TC) structure and intensity: it moved northward along the eastern coast of the United States, and weakened much faster than was predicted by the National Hurricane Center. Moreover, the minimum pressure in Irene occurred, atypically, about 40 h later than the time of maximum wind speed. In this study, we simulate Hurricane Irene with 1-km grid spacing using Spectral Bin Microphysics (SBM) and various bulk microphysical schemes in WRF. Simulations with SBM showed that aerosols penetrating the eyewall of Irene from the Saharan Air Layer (SAL) led to an intensification of convection at Irene's eyewall and to a deepening of the hurricane. When Irene moved along the eastern coast of the United States, continental aerosols led to an intensification of convection at Irene's periphery, which interfered with the re-forming of the inner eyewall and to Irene weakening. Sensitivity tests using different "bulk" microphysics schemes indicated a large dispersion of simulated minimum pressure and maximum wind between different simulations. This showed that the simulated hurricane intensity was very sensitive to microphysical processes. Moreover, in consequence, forecast hurricane intensity was highly dependent on the choice of microphysical scheme. New bulk-parameterization schemes simulated the tropical storm intensity of Irene reasonably well. Most bulk schemes that used saturation adjustment indicate the weak sensitivity to aerosols that prevents them from precisely predicting the time evolution of TC intensity and structure.

  18. 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.

  19. Black carbon mixing state impacts on cloud microphysical properties: effects of aerosol plume and environmental conditions

    SciTech Connect

    Ching, Ping Pui; Riemer, Nicole; West, Matthew

    2016-05-27

    Black carbon (BC) is usually mixed with other aerosol species within individual aerosol particles. This mixture, along with the particles' size and morphology, determines the particles' optical and cloud condensation nuclei properties, and hence black carbon's climate impacts. In this study the particle-resolved aerosol model PartMC-MOSAIC was used to quantify the importance of black carbon mixing state for predicting cloud microphysical quantities. Based on a set of about 100 cloud parcel simulations a process level analysis framework was developed to attribute the response in cloud microphysical properties to changes in the underlying aerosol population ("plume effect") and the cloud parcel cooling rate ("parcel effect"). It shows that the response of cloud droplet number concentration to changes in BC emissions depends on the BC mixing state. When the aerosol population contains mainly aged BC particles an increase in BC emission results in increasing cloud droplet number concentrations ("additive effect"). In contrast, when the aerosol population contains mainly fresh BC particles they act as sinks for condensable gaseous species, resulting in a decrease in cloud droplet number concentration as BC emissions are increased ("competition effect"). Additionally, we quantified the error in cloud microphysical quantities when neglecting the information on BC mixing state, which is often done in aerosol models. The errors ranged from -12% to +45% for the cloud droplet number fraction, from 0% to +1022% for the nucleation-scavenged black carbon (BC) mass fraction, from -12% to +4% for the effective radius, and from -30% to +60% for the relative dispersion.

  20. Investigation of Aerosol Indirect Effects using a Cumulus Microphysics Parameterization in a Regional Climate Model

    SciTech Connect

    Lim, Kyo-Sun; Fan, Jiwen; Leung, Lai-Yung R.; Ma, Po-Lun; Singh, Balwinder; Zhao, Chun; Zhang, Yang; Zhang, Guang; Song, Xiaoliang

    2014-01-29

    A new Zhang and McFarlane (ZM) cumulus scheme includes a two-moment cloud microphysics parameterization for convective clouds. This allows aerosol effects to be investigated more comprehensively by linking aerosols with microphysical processes in both stratiform clouds that are explicitly resolved and convective clouds that are parameterized in climate models. This new scheme is implemented in the Weather Research and Forecasting (WRF) model, which is coupled with the physics and aerosol packages from the Community Atmospheric Model version 5 (CAM5). A test case of July 2008 during the East Asian summer monsoon is selected to evaluate the performance of the new ZM scheme and to investigate aerosol effects on monsoon precipitation. The precipitation and radiative fluxes simulated by the new ZM scheme show a better agreement with observations compared to simulations with the original ZM scheme that does not include convective cloud microphysics and aerosol convective cloud interactions. Detailed analysis suggests that an increase in detrained cloud water and ice mass by the new ZM scheme is responsible for this improvement. To investigate precipitation response to increased anthropogenic aerosols, a sensitivity experiment is performed that mimics a clean environment by reducing the primary aerosols and anthropogenic emissions to 30% of that used in the control simulation of a polluted environment. The simulated surface precipitation is reduced by 9.8% from clean to polluted environment and the reduction is less significant when microphysics processes are excluded from the cumulus clouds. Ensemble experiments with ten members under each condition (i.e., clean and polluted) indicate similar response of the monsoon precipitation to increasing aerosols.

  1. Aerosol variability, synoptic-scale processes, and their link to the cloud microphysics over the northeast Pacific during MAGIC

    NASA Astrophysics Data System (ADS)

    Painemal, David; Minnis, Patrick; Nordeen, Michele

    2015-05-01

    Shipborne aerosol measurements collected from October 2012 to September 2013 along 36 transects between the port of Los Angeles, California (33.7°N, 118.2°), and Honolulu, Hawaii (21.3°N, 157.8°W), during the Marine ARM GPCI (Global Energy and Water Cycle Experiment (GEWEX)-Cloud System Study (GCSS)-Pacific Cross-section Intercomparison) Investigation of Clouds campaign are analyzed to determine the circulation patterns that modulate the synoptic and monthly variability of cloud condensation nuclei (CCN) in the boundary layer. Seasonal changes in CCN are evident, with low magnitudes during autumn/winter, and high CCN during spring/summer accompanied with a characteristic westward decrease. CCN monthly evolution is consistent with satellite-derived cloud droplet number concentration Nd from the Moderate Resolution Imaging Spectroradiometer. One-point correlation (r) analysis between the 1000 hPa zonal wind time series over a region between 125°W and 135°W, 35°N and 45°N, and the Nd field yields a negative r (up to -0.55) over a domain that covers a zonal extent of at least 20° from the California shoreline, indicating that Nd decreases when the zonal wind intensifies. The negative r expands southwestward as the zonal wind precedes Nd by up to 3 days, suggesting a transport mechanism from the coast of North America mediated by the California low-coastal jet, which intensifies in summer when the aerosol concentration and Nd reach a maximum. A first assessment of aerosol-cloud interaction (ACI) is performed by combining CCN and satellite Nd values from the Fifteenth Geostationary Operational Environmental Satellite. The CCN-Nd correlation is 0.66-0.69, and the ACI metric defined as ACI = ∂ln(Nd)/∂ln(CCN) is high at 0.9, similar to other aircraft-based studies and substantially greater than those inferred from satellites and climate models.

  2. Microphysics and chemistry of sulphate aerosols at warm stratospheric temperatures

    NASA Astrophysics Data System (ADS)

    Drdla, K.; Pueschel, R. F.; Strawa, A. W.; Cohen, R. C.; Hanisco, T. F.

    1999-11-01

    Observations of high NOx/NOy ratios (overall 40% larger than modelled values) during the Polar Ozone Loss in the Arctic Region in Summer campaign have led us to re-examine the heterogeneous chemistry of stratospheric aerosol particles during the polar summer period, using the Integrated MicroPhysics and Aerosol Chemistry on Trajectories model. The warm summer temperatures (up to 235 K) imply very concentrated sulphuric acid solutions (80 wt %). On the one hand, these solutions are more likely to freeze, into sulphuric acid monohydrate (SAM), reducing the efficiency of the N2O5 hydrolysis reaction. Including this freezing process increases NOx/NOy ratios but does not improve model/measurement agreement: in polar spring, SAM formation causes the NOx/NOy ratio to be overpredicted whereas freezing has a much smaller effect on nitrogen chemistry during the continuous solar exposure of polar summer. On the other hand, if sulphate aerosols remain liquid, the high acidity may promote acid-catalysed reactions. The most important reaction is CH2O + HNO3, which effectively increases NOx/NOy ratios across a wide range of conditions, improving agreement with measurements. Furthermore, the production of HONO can either enhance gas-phase OH concentrations or promote secondary liquid reactions, including HONO + HNO3 and HONO + HCl. Primary uncertainties include the uptake coefficient of CH2O relevant to reaction with HNO3, the amount of HONO available for secondary reaction, and the relative rates of HONO reaction with HNO3 and HCl. The fate of the formic acid product, whose presence in the stratosphere may be an indicator for the CH2O reaction, and the impact on the stratospheric hydrogen budget are also discussed.

  3. Indian Summer Monsoon Drought 2009: Role of Aerosol and Cloud Microphysics

    SciTech Connect

    Hazra, Anupam; Taraphdar, Sourav; Halder, Madhuparna; Pokhrel, S.; Chaudhari, H. S.; Salunke, K.; Mukhopadhyay, P.; Rao, S. A.

    2013-07-01

    Cloud dynamics played a fundamental role in defining Indian summer monsoon (ISM) rainfall during drought in 2009. The anomalously negative precipitation was consistent with cloud properties. Although, aerosols inhibited the growth of cloud effective radius in the background of sparse water vapor, their role is secondary. The primary role, however, is played by the interactive feedback between cloud microphysics and dynamics owing to reduced efficient cloud droplet growth, lesser latent heating release and shortage of water content. Cloud microphysical processes were instrumental for the occurrence of ISM drought 2009.

  4. Impact of volcanic ash plume aerosol on cloud microphysics

    NASA Astrophysics Data System (ADS)

    Martucci, G.; Ovadnevaite, J.; Ceburnis, D.; Berresheim, H.; Varghese, S.; Martin, D.; Flanagan, R.; O'Dowd, C. D.

    2012-03-01

    This study focuses on the dispersion of the Eyjafjallajökull volcanic ash plume over the west of Ireland, at the Mace Head Supersite, and its influence on cloud formation and microphysics during one significant event spanning May 16th and May 17th, 2010. Ground-based remote sensing of cloud microphysics was performed using a K a-band Doppler cloud RADAR, a LIDAR-ceilometer and a multi-channel microwave-radiometer combined with the synergistic analysis scheme SYRSOC ( Synergistic Remote Sensing Of Cloud). For this case study of volcanic aerosol interaction with clouds, cloud droplet number concentration (CDNC), liquid water content (LWC), and droplet effective radius ( reff) and the relative dispersion were retrieved. A unique cloud type formed over Mace Head characterized by layer-averaged maximum, mean and standard deviation values of the CDNC, reff and LWC: Nmax = 948 cm -3, N¯=297cm, σ=250cm, reff max = 35.5 μm, r¯=4.8μm, σ=4.4μm, LWC=0.23gm, LWC¯=0.055gm, σ=0.054gm, respectively. The high CDNC, for marine clean air, were associated with large accumulation mode diameter (395 nm) and a hygroscopic growth factor consistent with sulphuric acid aerosol, despite being almost exclusively internally mixed in submicron sizes. Additionally, the Condensation Nuclei (CN, d > 10 nm) to Cloud Condensation Nuclei (CCN) ratio, CCN:CN ˜1 at the moderately low supersaturation of 0.25%. This case study illustrates the influence of volcanic aerosols on cloud formation and microphysics and shows that volcanic aerosol can be an efficient CCN.

  5. 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

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. Meteorological and aerosol effects on marine cloud microphysical properties

    NASA Astrophysics Data System (ADS)

    Sanchez, K. J.; Russell, L. M.; Modini, R. L.; Frossard, A. A.; Ahlm, L.; Corrigan, C. E.; Roberts, G. C.; Hawkins, L. N.; Schroder, J. C.; Bertram, A. K.; Zhao, R.; Lee, A. K. Y.; Lin, J. J.; Nenes, A.; Wang, Z.; Wonaschütz, A.; Sorooshian, A.; Noone, K. J.; Jonsson, H.; Toom, D.; Macdonald, A. M.; Leaitch, W. R.; Seinfeld, J. H.

    2016-04-01

    Meteorology and microphysics affect cloud formation, cloud droplet distributions, and shortwave reflectance. The Eastern Pacific Emitted Aerosol Cloud Experiment and the Stratocumulus Observations of Los-Angeles Emissions Derived Aerosol-Droplets studies provided measurements in six case studies of cloud thermodynamic properties, initial particle number distribution and composition, and cloud drop distribution. In this study, we use simulations from a chemical and microphysical aerosol-cloud parcel (ACP) model with explicit kinetic drop activation to reproduce observed cloud droplet distributions of the case studies. Four cases had subadiabatic lapse rates, resulting in fewer activated droplets, lower liquid water content, and higher cloud base height than an adiabatic lapse rate. A weighted ensemble of simulations that reflect measured variation in updraft velocity and cloud base height was used to reproduce observed droplet distributions. Simulations show that organic hygroscopicity in internally mixed cases causes small effects on cloud reflectivity (CR) (<0.01), except for cargo ship and smoke plumes, which increased CR by 0.02 and 0.07, respectively, owing to their high organic mass fraction. Organic hygroscopicity had larger effects on droplet concentrations for cases with higher aerosol concentrations near the critical diameter (namely, polluted cases with a modal peak near 0.1 µm). Differences in simulated droplet spectral widths (k) caused larger differences in CR than organic hygroscopicity in cases with organic mass fractions of 60% or less for the cases shown. Finally, simulations from a numerical parameterization of cloud droplet activation suitable for general circulation models compared well with the ACP model, except under high organic mass fraction.

  11. 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.

  12. Meteorological and Aerosol effects on Marine Cloud Microphysical Properties

    NASA Astrophysics Data System (ADS)

    Sanchez, K. J.; Russell, L. M.; Modini, R. L.; Frossard, A. A.; Ahlm, L.; Roberts, G.; Hawkins, L. N.; Schroder, J. C.; Wang, Z.; Lee, A.; Abbatt, J.; Lin, J.; Nenes, A.; Wonaschuetz, A.; Sorooshian, A.; Noone, K.; Jonsson, H.; Albrecht, B. A.; Desiree, T. S.; Macdonald, A. M.; Seinfeld, J.; Zhao, R.

    2015-12-01

    Both meteorology and microphysics affect cloud formation and consequently their droplet distributions and shortwave reflectance. The Eastern Pacific Emitted Aerosol Cloud Experiment (EPEACE) and the Stratocumulus Observations of Los-Angeles Emissions Derived Aerosol-Droplets (SOLEDAD) studies provide detailed measurements in 6 case studies of both cloud thermodynamic properties and initial particle number distribution and composition, as well as the resulting cloud drop distribution and composition. This study uses simulations of a detailed chemical and microphysical aerosol-cloud parcel (ACP) model with explicit kinetic drop activation to reproduce the observed cloud droplet distribution and composition. Four of the cases examined had a sub-adiabatic lapse rate, which was shown to have fewer droplets due to decreased maximum supersaturation, lower LWC and higher cloud base height, consistent with previous findings. These detailed case studies provided measured thermodynamics and microphysics that constrained the simulated droplet size distribution sufficiently to match the droplet number within 6% and the size within 19% for 4 of the 6 cases, demonstrating "closure" or consistency of the measured composition with the measured CCN spectra and the inferred and modeled supersaturation. The contribution of organic components to droplet formation shows small effects on the droplet number and size in the 4 marine cases that had background aerosol conditions with varying amounts of coastal, ship or other non-biogenic sources. In contrast, the organic fraction and hygroscopicity increased the droplet number and size in the cases with generated smoke and cargo ship plumes that were freshly emitted and not yet internally mixed with the background particles. The simulation results show organic hygroscopicity causes small effects on cloud reflectivity (<0.7%) with the exception of the cargo ship plume and smoke plume which increased absolute cloud reflectivity fraction by 0

  13. A global modeling study on carbonaceous aerosol microphysical characteristics and radiative forcing

    NASA Astrophysics Data System (ADS)

    Bauer, S. E.; Menon, S.; Koch, D.; Bond, T. C.; Tsigaridis, K.

    2010-02-01

    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, cloud-indirect and semi-direct forcing 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 forcing. Our best estimate for net direct and indirect aerosol radiative forcing 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 forcing can vary between -0.32 to -0.75 W/m2 depending on these carbonaceous particle properties at emission. Assuming that sulfates, nitrates and secondary organics form a coating around a black carbon core, rather than forming a uniformly mixed particle, changes the overall net aerosol radiative forcing from negative to positive. Taking into account internally mixed black carbon particles let us simulate correct aerosol absorption. Black carbon absorption is amplified by sulfate and nitrate coatings, but even more strongly by organic coatings. Black carbon mitigation scenarios generally showed reduced radiative forcing when 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 climate benefits.

  14. 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

  15. Aerosol impacts on radiative and microphysical properties of clouds and precipitation formation

    NASA Astrophysics Data System (ADS)

    Alizadeh-Choobari, O.; Gharaylou, M.

    2017-03-01

    Through modifying the number concentration and size of cloud droplets, aerosols have intricate impacts on radiative and microphysical properties of clouds, which together influence precipitation processes. Aerosol-cloud interactions for a mid-latitude convective cloud system are investigated using a two-moment aerosol-aware bulk microphysical scheme implemented into the Weather Research and Forecasting (WRF) model. Three sensitivity experiments with initial identical dynamic and thermodynamic conditions, but different cloud-nucleating aerosol concentrations were conducted. Increased aerosol number concentration has resulted in more numerous cloud droplets of overall smaller sizes, through which the optical properties of clouds have been changed. While the shortwave cloud forcing is significantly increased in more polluted experiments, changes in the aerosol number concentration have negligible impacts on the longwave cloud forcing. For the first time, it is found that polluted clouds have higher cloud base heights, the feature that is caused by more surface cooling due to a higher shortwave cloud forcing, as well as a drier boundary layer in the polluted experiment compared to the clean. The polluted experiment was also associated with a higher liquid water content (LWC), caused by an increase in the number of condensation of water vapor due to higher concentration of hygroscopic aerosols acting as condensation nuclei. The domain-averaged accumulated precipitation is little changed under both polluted and clean atmosphere. Nevertheless, changes in the rate of precipitation are identified, such that under polluted atmosphere light rain is reduced, while both moderate and heavy rain are intensified, confirming the fact that if an ample influx of water vapor exists, an increment of hygroscopic aerosols can increase the amount of precipitation.

  16. A Fast and Efficient Version of the TwO-Moment Aerosol Sectional (TOMAS) Global Aerosol Microphysics Model

    NASA Technical Reports Server (NTRS)

    Lee, Yunha; Adams, P. J.

    2012-01-01

    This study develops more computationally efficient versions of the TwO-Moment Aerosol Sectional (TOMAS) microphysics algorithms, collectively called Fast TOMAS. Several methods for speeding up the algorithm were attempted, but only reducing the number of size sections was adopted. Fast TOMAS models, coupled to the GISS GCM II-prime, require a new coagulation algorithm with less restrictive size resolution assumptions but only minor changes in other processes. Fast TOMAS models have been evaluated in a box model against analytical solutions of coagulation and condensation and in a 3-D model against the original TOMAS (TOMAS-30) model. Condensation and coagulation in the Fast TOMAS models agree well with the analytical solution but show slightly more bias than the TOMAS-30 box model. In the 3-D model, errors resulting from decreased size resolution in each process (i.e., emissions, cloud processing wet deposition, microphysics) are quantified in a series of model sensitivity simulations. Errors resulting from lower size resolution in condensation and coagulation, defined as the microphysics error, affect number and mass concentrations by only a few percent. The microphysics error in CN70CN100 (number concentrations of particles larger than 70100 nm diameter), proxies for cloud condensation nuclei, range from 5 to 5 in most regions. The largest errors are associated with decreasing the size resolution in the cloud processing wet deposition calculations, defined as cloud-processing error, and range from 20 to 15 in most regions for CN70CN100 concentrations. Overall, the Fast TOMAS models increase the computational speed by 2 to 3 times with only small numerical errors stemming from condensation and coagulation calculations when compared to TOMAS-30. The faster versions of the TOMAS model allow for the longer, multi-year simulations required to assess aerosol effects on cloud lifetime and precipitation.

  17. Coupling Spectral-bin Cloud Microphysics with the MOSAIC Aerosol Model in WRF-Chem: Methodology and Results for Marine Stratocumulus Clouds

    SciTech Connect

    Gao, Wenhua; Fan, Jiwen; Easter, Richard C.; Yang, Qing; Zhao, Chun; Ghan, Steven J.

    2016-08-23

    Aerosol-cloud interaction processes can be represented more physically with bin cloud microphysics relative to bulk microphysical parameterizations. However, due to computational power limitations in the past, bin cloud microphysics was often run with very simple aerosol treatments. The purpose of this study is to represent better aerosol-cloud interaction processes in the Chemistry version of Weather Research and Forecast model (WRF-Chem) at convection-permitting scales by coupling spectral-bin cloud microphysics (SBM) with the MOSAIC sectional aerosol model. A flexible interface is built that exchanges cloud and aerosol information between them. The interface contains a new bin aerosol activation approach, which replaces the treatments in the original SBM. It also includes the modified aerosol resuspension and in-cloud wet removal processes with the droplet loss tendencies and precipitation fluxes from SBM. The newly coupled system is evaluated for two marine stratocumulus cases over the Southeast Pacific Ocean with either a simplified aerosol setup or full-chemistry. We compare the aerosol activation process in the newly-coupled SBM-MOSAIC against the SBM simulation without chemistry using a simplified aerosol setup, and the results show consistent activation rates. A longer time simulation reinforces that aerosol resuspension through cloud drop evaporation plays an important role in replenishing aerosols and impacts cloud and precipitation in marine stratocumulus clouds. Evaluation of the coupled SBM-MOSAIC with full-chemistry using aircraft measurements suggests that the new model works realistically for the marine stratocumulus clouds, and improves the simulation of cloud microphysical properties compared to a simulation using MOSAIC coupled with the Morrison two-moment microphysics.

  18. Coupling spectral-bin cloud microphysics with the MOSAIC aerosol model in WRF-Chem: Methodology and results for marine stratocumulus clouds

    NASA Astrophysics Data System (ADS)

    Gao, Wenhua; Fan, Jiwen; Easter, R. C.; Yang, Qing; Zhao, Chun; Ghan, Steven J.

    2016-09-01

    Aerosol-cloud interaction processes can be represented more physically with bin cloud microphysics relative to bulk microphysical parameterizations. However, due to computational power limitations in the past, bin cloud microphysics was often run with very simple aerosol treatments. The purpose of this study is to represent better aerosol-cloud interaction processes in the Chemistry version of Weather Research and Forecast model (WRF-Chem) at convection-permitting scales by coupling spectral-bin cloud microphysics (SBM) with the MOSAIC sectional aerosol model. A flexible interface is built that exchanges cloud and aerosol information between them. The interface contains a new bin aerosol activation approach, which replaces the treatments in the original SBM. It also includes the modified aerosol resuspension and in-cloud wet removal processes with the droplet loss tendencies and precipitation fluxes from SBM. The newly coupled system is evaluated for two marine stratocumulus cases over the Southeast Pacific Ocean with either a simplified aerosol setup or full-chemistry. We compare the aerosol activation process in the newly coupled SBM-MOSAIC against the SBM simulation without chemistry using a simplified aerosol setup, and the results show consistent activation rates. A longer time simulation reinforces that aerosol resuspension through cloud drop evaporation plays an important role in replenishing aerosols and impacts cloud and precipitation in marine stratocumulus clouds. Evaluation of the coupled SBM-MOSAIC with full-chemistry using aircraft measurements suggests that the new model works realistically for the marine stratocumulus clouds, and improves the simulation of cloud microphysical properties compared to a simulation using MOSAIC coupled with the Morrison two-moment microphysics.

  19. Microphysical modeling of Titan's aerosols - Application to the in situ analysis

    NASA Astrophysics Data System (ADS)

    Frere, C.; Raulin, F.; Israel, G.; Cabane, M.

    Microphysical modeling of Titan's aerosols has been developed in order to estimate the distribution and chemical composition of the particles in the low atmosphere. It includes condensation, diffusion, coagulation and sedimentation processes, and it uses up-to-date data relating to the vertical thermal and chemical atmospheric structure. The main results indicate that, down to a few km above the surface, the aerosol clouds would be constituted of particles of mean radius increasing with decreasing altitude, with a solid core of several 10 microns, mainly composed of nitriles, and covered by a thick layer of C1-C2 hydrocarbons. These results have important implications on future in situ aerosol analysis experiments, like Cassini's ACP experiment.

  20. Intercomparison and Evaluation of Global Aerosol Microphysical Properties Among Aerocom Models of a Range of Complexity

    NASA Technical Reports Server (NTRS)

    Mann, G. W.; Carslaw, K. S.; Reddington, C. L.; Pringle, K. J.; Schulz, M.; Asmi, A.; Spracklen, D. V.; Ridley, D. A.; Woodhouse, M. T.; Lee, L. A.; Zhang, K.; Ghan, S. J.; Easter, R. C.; Liu, X.; Stier, P.; Lee, Y. H; Adams, P. J.; Tost, H.; Lelieveld, J.; Bauer, S. E.; Tsigaridis, K.; van Noije, T. P. C.; Strunk, A.; Vignati, E.; Bellouin, N.

    2014-01-01

    Many of the next generation of global climate models will include aerosol schemes which explicitly simulate the microphysical processes that determine the particle size distribution. These models enable aerosol optical properties and cloud condensation nuclei (CCN) concentrations to be determined by fundamental aerosol processes, which should lead to a more physically based simulation of aerosol direct and indirect radiative forcings. This study examines the global variation in particle size distribution simulated by 12 global aerosol microphysics models to quantify model diversity and to identify any common biases against observations. Evaluation against size distribution measurements from a new European network of aerosol supersites shows that the mean model agrees quite well with the observations at many sites on the annual mean, but there are some seasonal biases common to many sites. In particular, at many of these European sites, the accumulation mode number concentration is biased low during winter and Aitken mode concentrations tend to be overestimated in winter and underestimated in summer. At high northern latitudes, the models strongly underpredict Aitken and accumulation particle concentrations compared to the measurements, consistent with previous studies that have highlighted the poor performance of global aerosol models in the Arctic. In the marine boundary layer, the models capture the observed meridional variation in the size distribution, which is dominated by the Aitken mode at high latitudes, with an increasing concentration of accumulation particles with decreasing latitude. Considering vertical profiles, the models reproduce the observed peak in total particle concentrations in the upper troposphere due to new particle formation, although modelled peak concentrations tend to be biased high over Europe. Overall, the multimodel- mean data set simulates the global variation of the particle size distribution with a good degree of skill, suggesting

  1. Cloud Processed CCN Affect Cloud Microphysics

    NASA Astrophysics Data System (ADS)

    Hudson, J. G.; Noble, S. R., Jr.; Tabor, S. S.

    2015-12-01

    Variations in the bimodality/monomodality of CCN spectra (Hudson et al. 2015) exert opposite effects on cloud microphysics in two aircraft field projects. The figure shows two examples, droplet concentration, Nc, and drizzle liquid water content, Ld, against classification of CCN spectral modality. Low ratings go to balanced separated bimodal spectra, high ratings go to single mode spectra, strictly monomodal 8. Intermediate ratings go merged modes, e.g., one mode a shoulder of another. Bimodality is caused by mass or hygroscopicity increases that go only to CCN that made activated cloud droplets. In the Ice in Clouds Experiment-Tropical (ICE-T) small cumuli with lower Nc, greater droplet mean diameters, MD, effective radii, re, spectral widths, σ, cloud liquid water contents, Lc, and Ld were closer to more bimodal (lower modal ratings) below cloud CCN spectra whereas clouds with higher Nc, smaller MD, re, σ, and Ld were closer to more monomodal CCN (higher modal ratings). In polluted stratus clouds of the MArine Stratus/Stratocumulus Experiment (MASE) clouds that had greater Nc, and smaller MD, re, σ, Lc, and Ld were closer to more bimodal CCN spectra whereas clouds with lower Nc, and greater MD, re, σ, Lc, and Ld were closer to more monomodal CCN. These relationships are opposite because the dominant ICE-T cloud processing was coalescence whereas chemical transformations (e.g., SO2 to SO4) were dominant in MASE. Coalescence reduces Nc and thus also CCN concentrations (NCCN) when droplets evaporate. In subsequent clouds the reduced competition increases MD and σ, which further enhance coalescence and drizzle. Chemical transformations do not change Nc but added sulfate enhances droplet and CCN solubility. Thus, lower critical supersaturation (S) CCN can produce more cloud droplets in subsequent cloud cycles, especially for the low W and effective S of stratus. The increased competition reduces MD, re, and σ, which inhibit coalescence and thus reduce drizzle

  2. Microphysical Processes Affecting the Pinatubo Volcanic Plume

    NASA Technical Reports Server (NTRS)

    Hamill, Patrick; Houben, Howard; Young, Richard; Turco, Richard; Zhao, Jingxia

    1996-01-01

    In this paper we consider microphysical processes which affect the formation of sulfate particles and their size distribution in a dispersing cloud. A model for the dispersion of the Mt. Pinatubo volcanic cloud is described. We then consider a single point in the dispersing cloud and study the effects of nucleation, condensation and coagulation on the time evolution of the particle size distribution at that point.

  3. 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.

  4. 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.

  5. 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

  6. Assessment of aerosol optics, microphysics, and transport process of biomass-burning haze over northern SE Asia: 7-SEAS AERONET observations

    NASA Astrophysics Data System (ADS)

    Wang, S.; Giles, D. M.; Eck, T. F.; Lin, N.; Tsay, S.; Holben, B. N.

    2013-12-01

    Initiated in 2007, the Seven South East Asian Studies (7-SEAS) is aimed to facilitate an interdisciplinary research on the aerosol environment in SE Asia (SEA) as a whole, promote international collaboration, and further enhance scientific understanding of the impact of biomass burning on clouds, atmospheric radiation, hydrological cycle, and region climates. One of the key measurements proposed in the 7-SEAS is the NASA/AERONET (AErosol RObotic NETwork) observation, which provides helpful information on columnar aerosol optical properties and allows us consistently to examine biomass-burning aerosols across northern SEA from ground-based remote-sensing point of view. In this presentation, we will focus on the two 7-SEAS field deployments, i.e. the 2012 Son La Experiment and the 2013 BASELInE (Biomass-burning Aerosols & Stratocumulus Environment: Lifecycles and Interactions Experiment). We analyze the daytime variation of aerosol by using consistent measurements from 15 of AERONET sites over Indochina, the South China Sea, and Taiwan. Spatiotemporal characteristics of aerosol optical properties (e.g., aerosol optical depth (AOD), fine/coarse mode AOD, single-scattering albedo, asymmetry factor) will be discussed. Strong diurnal variation of aerosol optical properties was observed to be attributed to planetary boundary layer (PBL) dynamics. A comparison between aerosol loading (i.e. AOD) and surface PM2.5 concentration will be presented. Our results demonstrate that smoke aerosols emitted from agriculture burning that under certain meteorological conditions can degrade regional air quality 3000 km from the source region, with additional implications for aerosol radiative forcing and regional climate change over northern SE Asia.

  7. Applying super-droplets as a compact representation of warm-rain microphysics for aerosol-cloud-aerosol interactions

    NASA Astrophysics Data System (ADS)

    Arabas, S.; Jaruga, A.; Pawlowska, H.; Grabowski, W. W.

    2012-12-01

    Clouds may influence aerosol characteristics of their environment. The relevant processes include wet deposition (rainout or washout) and cloud condensation nuclei (CCN) recycling through evaporation of cloud droplets and drizzle drops. Recycled CCN physicochemical properties may be altered if the evaporated droplets go through collisional growth or irreversible chemical reactions (e.g. SO2 oxidation). The key challenge of representing these processes in a numerical cloud model stems from the need to track properties of activated CCN throughout the cloud lifecycle. Lack of such "memory" characterises the so-called bulk, multi-moment as well as bin representations of cloud microphysics. In this study we apply the particle-based scheme of Shima et al. 2009. Each modelled particle (aka super-droplet) is a numerical proxy for a multiplicity of real-world CCN, cloud, drizzle or rain particles of the same size, nucleus type,and position. Tracking cloud nucleus properties is an inherent feature of the particle-based frameworks, making them suitable for studying aerosol-cloud-aerosol interactions. The super-droplet scheme is furthermore characterized by linear scalability in the number of computational particles, and no numerical diffusion in the condensational and in the Monte-Carlo type collisional growth schemes. The presentation will focus on processing of aerosol by a drizzling stratocumulus deck. The simulations are carried out using a 2D kinematic framework and a VOCALS experiment inspired set-up (see http://www.rap.ucar.edu/~gthompsn/workshop2012/case1/).

  8. Numerical studies of microphysical modulations of stratospheric aerosol within ROMIC-ROSA

    NASA Astrophysics Data System (ADS)

    Hommel, René; von Savigny, Christian; Rozanov, Alexei; Burrows, John; Zalach, Jakob

    2016-04-01

    The stratospheric aerosol layer (so-called Junge layer) is an inherent part of the Brewer-Dobson circulation (BDC). Stratospheric aerosols play a large role in the Earth's climate system because they interact with catalytic cycles depleting ozone, directly alter the atmosphere's radiative balance and modulate the strength of polar vortices, in particular when this system is perturbed. In terms of mass the layer is predominantly composed of liquid sulphate-water droplets and is fed from the oxidation of gaseous precursors reaching the stratosphere either by direct volcanic injections (mainly supplying SO2) or troposphere-stratosphere exchange processes. In volcanically quiescent periods, latter processes predominantly maintain the so-called background state of aerosol layer through oxidation of OCS above 22 km, and SO2 below. The Junge layer begins to develop 2-3 km above the tropopause and reaches a height of about 35 km, with a largest vertical extent in the tropics and spring-time polar regions. Above the TTL, the layer's vertical extent varies between 2 km and 8 km (about 35% of its mean vertical expansion), depending on the phase of the QBO. The QBO-induced meridional circulation, overlying the BDC, and accompanied signatures in the stratospheric temperature directly affect the life cycle of stratospheric aerosol. Mainly by modulating the equilibrium between microphysical processes which maintain the layer. Effects caused by QBO modulations of the advective transport in the upwelling region of the BDC are smaller and difficult to quantify, because the overlying sedimentation of aerosol is also being modulated and counteract the aerosol lofting. Here we show results from numerical studies performed within the project ROMIC-ROSA (Role of Stratospheric Aerosol in Climate and Atmospheric Science). We further explored relationships between QBO forcing and aerosol processes in the lower stratosphere. We examined whether similar process interferences can be caused by

  9. High resolution simulations of aerosol microphysics in a global and regionally nested chemical transport model

    NASA Astrophysics Data System (ADS)

    Adams, P. J.; Marks, M.

    2015-12-01

    The aerosol indirect effect is the largest source of forcing uncertainty in current climate models. This effect arises from the influence of aerosols on the reflective properties and lifetimes of clouds, and its magnitude depends on how many particles can serve as cloud droplet formation sites. Assessing levels of this subset of particles (cloud condensation nuclei, or CCN) requires knowledge of aerosol levels and their global distribution, size distributions, and composition. A key tool necessary to advance our understanding of CCN is the use of global aerosol microphysical models, which simulate the processes that control aerosol size distributions: nucleation, condensation/evaporation, and coagulation. Previous studies have found important differences in CO (Chen, D. et al., 2009) and ozone (Jang, J., 1995) modeled at different spatial resolutions, and it is reasonable to believe that short-lived, spatially-variable aerosol species will be similarly - or more - susceptible to model resolution effects. The goal of this study is to determine how CCN levels and spatial distributions change as simulations are run at higher spatial resolution - specifically, to evaluate how sensitive the model is to grid size, and how this affects comparisons against observations. Higher resolution simulations are necessary supports for model/measurement synergy. Simulations were performed using the global chemical transport model GEOS-Chem (v9-02). The years 2008 and 2009 were simulated at 4ox5o and 2ox2.5o globally and at 0.5ox0.667o over Europe and North America. Results were evaluated against surface-based particle size distribution measurements from the European Supersites for Atmospheric Aerosol Research project. The fine-resolution model simulates more spatial and temporal variability in ultrafine levels, and better resolves topography. Results suggest that the coarse model predicts systematically lower ultrafine levels than does the fine-resolution model. Significant

  10. Airborne In-Situ Measurements of Aerosol and Cloud Microphysical Properties in Mixed-Phase Clouds Under Varying Conditions

    NASA Astrophysics Data System (ADS)

    Comstock, J. M.; Fan, J.; Tomlinson, J. M.; Mei, F.; Hubbe, J. M.; Schmid, B.

    2014-12-01

    Cloud microphysical properties impact the interaction of clouds and radiation in the atmosphere, and can influence atmospheric circulations through changes in cloud phase. Characterizing the conditions that control phase changes and the microphysical properties of mixed-phase clouds is important for improving understanding of physical processes that influence cloud phase. We characterize the aerosol and cloud microphysical properties in relation to the atmospheric dynamic and thermodynamic conditions observed in mixed-phase clouds during several aircraft-based field experiments. The Department of Energy Atmospheric Radiation Measurement program's Gulfstream-1 aircraft was used to sample aerosol and cloud properties in warm and cold clouds during several recent field experiments. We analyze in-situ observations from the CalWater and TCAP field campaigns to examine the variability of cloud properties (phase, hydrometeor size, ice and liquid water content, particle habit) with changes in aerosol, vertical velocity, and temperature. These measurements indicate that in addition to aerosol concentration, vertical velocity strength has important influence on cloud phase in mixed-phase cloud regimes.

  11. Study of Midlatitude and Arctic Aerosol-Cloud-Radiation Feedbacks Based on LES Model with Explicit Ice and Liquid Phase Microphysics.

    DTIC Science & Technology

    2007-11-02

    validate the CIMMS LES model and to improve our understanding of the interaction between the microphysical, radiative, and thermodynamical processes...modeling part of the research will be based on the CIMMS 3-D LES model of a stratocumulus cloud layer that includes an explicit formulation of aerosol...and cloud drop size resolving microphysics and radiation. The study of mixed phase clouds will use the new version of the CIMMS model which includes

  12. 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

  13. Microphysical aerosol parameters of spheroidal particles via regularized inversion of lidar data

    NASA Astrophysics Data System (ADS)

    Samaras, Stefanos; Böckmann, Christine

    2015-04-01

    One of the main topics in understanding the aerosol impact on climate requires the investigation of the spatial and temporal variability of microphysical properties of particles, e.g., the complex refractive index, the effective radius, the volume and surface-area concentration, and the single-scattering albedo. Remote sensing is a technique used to monitor aerosols in global coverage and fill in the observational gap. This research topic involves using multi-wavelength Raman lidar systems to extract the microphysical properties of aerosol particles, along with depolarization signals to account for the non-sphericity of the latter. Given, the optical parameters (measured by a lidar), the kernel functions, which summarize the size, shape and composition of particles, we solve for the size distribution of the particles modeled by a Fredholm integral system and further calculate the refractive index. This model works well for spherical particles (e.g. smoke); the kernel functions are derived from relatively simplified formulas (Mie scattering theory) and research has led to successful retrievals for particles which at least resemble a spherical geometry (small depolarization ratio). Obviously, more complicated atmospheric structures (e.g dust) require employment of non-spherical kernels and/or more complicated models which are investigated in this paper. The new model is now a two-dimensional one including the aspect ratio of spheroidal particles. The spheroidal kernel functions are able to be calculated via T-Matrix; a technique used for computing electromagnetic scattering by single, homogeneous, arbitrarily shaped particles. In order to speed up the process and massively perform simulation tests, we created a software interface using different regularization methods and parameter choice rules. The following methods have been used: Truncated singular value decomposition and Pade iteration with the discrepancy principle, and Tikhonov regularization with the L

  14. Microphysical Effects Determine Macrophysical Response for Aerosol Impacts on Deep Convective Clouds

    SciTech Connect

    Fan, Jiwen; Leung, Lai-Yung R.; Rosenfeld, Daniel; Chen, Qian; Li, Zhanqing; Zhang, Jinqiang; Yan, Hongru

    2013-11-26

    Deep convective clouds (DCCs) play a crucial role in the general circulation and energy and hydrological cycle of our climate system. Anthropogenic and natural aerosol particles can influence DCCs through changes in cloud properties, precipitation regimes, and radiation balance. Modeling studies have reported both invigoration and suppression of DCCs by aerosols, but none has fully quantified aerosol impacts on convection life cycle and radiative forcing. By conducting multiple month-long cloud-resolving simulations with spectral-bin cloud microphysics that capture the observed macro- and micro-physical properties of summer convective clouds in the tropics and mid-latitudes, this study provides the first comprehensive look at how aerosols affect cloud cover, cloud top height (CTH), and radiative forcing. Observations validate these simulation results. We find that microphysical aerosol effects contribute predominantly to increased cloud cover and CTH by inducing larger amount of smaller but longer lasting ice particles in the stratiform/anvils of DCCs with dynamical aerosol effects contributing at most ~ 1/4 of the total increase of cloud cover. The overall effect is a radiative warming in the atmosphere (3 to 5 W m-2) with strong surface cooling (-5 to -8 W m-2). Herein we clearly identified mechanisms more important than and additional to the invigoration effects hypothesized previously that explain the consistent signatures of increased cloud tops area and height by aerosols in DCCs revealed by observations.

  15. Implementation of an Aerosol-Cloud Microphysics-Radiation Coupling into the NASA Unified WRF: Simulation Results for the 6-7 August 2006 AMMA Special Observing Period

    NASA Technical Reports Server (NTRS)

    Shi, J. J.; Matsui, T.; Tao, W.-K.; Tan, Q.; Peters-Lidard, C.; Chin, M.; Pickering, K.; Guy, N.; Lang, S.; Kemp, E. M.

    2014-01-01

    Aerosols affect the Earth's radiation balance directly and cloud microphysical processes indirectly via the activation of cloud condensation and ice nuclei. These two effects have often been considered separately and independently, hence the need to assess their combined impact given the differing nature of their effects on convective clouds. To study both effects, an aerosol-microphysics-radiation coupling, including Goddard microphysics and radiation schemes, was implemented into the NASA Unified Weather Research and Forecasting model (NU-WRF). Fully coupled NU-WRF simulations were conducted for a mesoscale convective system (MCS) that passed through the Niamey, Niger area on 6-7 August 2006 during an African Monsoon Multidisciplinary Analysis (AMMA) special observing period. The results suggest that rainfall is reduced when aerosol indirect effects are included, regardless of the aerosol direct effect. Daily mean radiation heating profiles in the area traversed by the MCS showed the aerosol (mainly mineral dust) direct effect had the largest impact near cloud tops just above 200 hectopascals where short-wave heating increased by about 0.8 Kelvin per day; the weakest long-wave cooling was at around 250 hectopascals. It was also found that more condensation and ice nuclei as a result of higher aerosol/dust concentrations led to increased amounts of all cloud hydrometeors because of the microphysical indirect effect, and the radiation direct effect acts to reduce precipitating cloud particles (rain, snow and graupel) in the middle and lower cloud layers while increasing the non-precipitating particles (ice) in the cirrus anvil. However, when the aerosol direct effect was activated, regardless of the indirect effect, the onset of MCS precipitation was delayed about 2 hours, in conjunction with the delay in the activation of cloud condensation and ice nuclei. Overall, for this particular environment, model set-up and physics configuration, the effect of aerosol

  16. Using Raman-lidar-based regularized microphysical retrievals and Aerosol Mass Spectrometer measurements for the characterization of biomass burning aerosols

    NASA Astrophysics Data System (ADS)

    Samaras, Stefanos; Nicolae, Doina; Böckmann, Christine; Vasilescu, Jeni; Binietoglou, Ioannis; Labzovskii, Lev; Toanca, Florica; Papayannis, Alexandros

    2015-10-01

    In this work we extract the microphysical properties of aerosols for a collection of measurement cases with low volume depolarization ratio originating from fire sources captured by the Raman lidar located at the National Institute of Optoelectronics (INOE) in Bucharest. Our algorithm was tested not only for pure smoke but also for mixed smoke and urban aerosols of variable age and growth. Applying a sensitivity analysis on initial parameter settings of our retrieval code was proved vital for producing semi-automatized retrievals with a hybrid regularization method developed at the Institute of Mathematics of Potsdam University. A direct quantitative comparison of the retrieved microphysical properties with measurements from a Compact Time of Flight Aerosol Mass Spectrometer (CToF-AMS) is used to validate our algorithm. Microphysical retrievals performed with sun photometer data are also used to explore our results. Focusing on the fine mode we observed remarkable similarities between the retrieved size distribution and the one measured by the AMS. More complicated atmospheric structures and the factor of absorption appear to depend more on particle radius being subject to variation. A good correlation was found between the aerosol effective radius and particle age, using the ratio of lidar ratios (LR: aerosol extinction to backscatter ratios) as an indicator for the latter. Finally, the dependence on relative humidity of aerosol effective radii measured on the ground and within the layers aloft show similar patterns.

  17. 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.

  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. Microphysical effects determine macrophysical response for aerosol impacts on deep convective clouds.

    PubMed

    Fan, Jiwen; Leung, L Ruby; Rosenfeld, Daniel; Chen, Qian; Li, Zhanqing; Zhang, Jinqiang; Yan, Hongru

    2013-11-26

    Deep convective clouds (DCCs) play a crucial role in the general circulation, energy, and hydrological cycle of our climate system. Aerosol particles can influence DCCs by altering cloud properties, precipitation regimes, and radiation balance. Previous studies reported both invigoration and suppression of DCCs by aerosols, but few were concerned with the whole life cycle of DCC. By conducting multiple monthlong cloud-resolving simulations with spectral-bin cloud microphysics that capture the observed macrophysical and microphysical properties of summer convective clouds and precipitation in the tropics and midlatitudes, this study provides a comprehensive view of how aerosols affect cloud cover, cloud top height, and radiative forcing. We found that although the widely accepted theory of DCC invigoration due to aerosol's thermodynamic effect (additional latent heat release from freezing of greater amount of cloud water) may work during the growing stage, it is microphysical effect influenced by aerosols that drives the dramatic increase in cloud cover, cloud top height, and cloud thickness at the mature and dissipation stages by inducing larger amounts of smaller but longer-lasting ice particles in the stratiform/anvils of DCCs, even when thermodynamic invigoration of convection is absent. The thermodynamic invigoration effect contributes up to ~27% of total increase in cloud cover. The overall aerosol indirect effect is an atmospheric radiative warming (3-5 W m(-2)) and a surface cooling (-5 to -8 W m(-2)). The modeling findings are confirmed by the analyses of ample measurements made at three sites of distinctly different environments.

  20. Microphysical, chemical and optical aerosol properties in the Baltic Sea region

    NASA Astrophysics Data System (ADS)

    Kikas, Ülle; Reinart, Aivo; Pugatshova, Anna; Tamm, Eduard; Ulevicius, Vidmantas

    2008-11-01

    The microphysical structure, chemical composition and prehistory of aerosol are related to the aerosol optical properties and radiative effect in the UV spectral range. The aim of this work is the statistical mapping of typical aerosol scenarios and adjustment of regional aerosol parameters. The investigation is based on the in situ measurements in Preila (55.55° N, 21.00° E), Lithuania, and the AERONET data from the Gustav Dalen Tower (58 N, 17 E), Sweden. Clustering of multiple characteristics enabled to distinguish three aerosol types for clear-sky periods: 1) clean maritime-continental aerosol; 2) moderately polluted maritime-continental aerosol; 3) polluted continental aerosol. Differences between these types are due to significant differences in aerosol number and volume concentration, effective radius of volume distribution, content of SO 4- ions and Black Carbon, as well as different vertical profiles of atmospheric relative humidity. The UV extinction, aerosol optical depth (AOD) and the Ångstrom coefficient α increased with the increasing pollution. The value α = 1.96 was observed in the polluted continental aerosol that has passed over central and eastern Europe and southern Russia. Reduction of the clear-sky UV index against the aerosol-free atmosphere was of 4.5%, 27% and 41% for the aerosol types 1, 2 and 3, respectively.

  1. 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

  2. Intercomparison and Evaluation of Global Aerosol Microphysical Properties among AeroCom Models of a Range of Complexity

    SciTech Connect

    Mann, G. W.; Carslaw, K. S.; Reddington, C. L.; Pringle, K. J.; Schulz, M.; Asmi, A.; Spracklen, D. V.; Ridley, D. A.; Woodhouse, M. T.; Lee, L. A.; Zhang, Kai; Ghan, Steven J.; Easter, Richard C.; Liu, Xiaohong; Stier, P.; Lee, Y. H.; Adams, P. J.; Tost, H.; Lelieveld, J.; Bauer, S.; Tsigaridis, Kostas; van Noije, T.; Strunk, A.; Vignati, E.; Bellouin, N.; Dalvi, M.; Johnson, C. E.; Bergman, T.; Kokkola, H.; Von Salzen, Knut; Yu, Fangqun; Luo, Gan; Petzold, A.; Heintzenberg, J.; Clarke, A. D.; Ogren, J. A.; Gras, J.; Baltensperger, Urs; Kaminski, U.; Jennings, S. G.; O'Dowd, C. D.; Harrison, R. M.; Beddows, D. C.; Kulmala, M.; Viisanen, Y.; Ulevicius, V.; Mihalopoulos, Nikos; Zdimal, V.; Fiebig, M.; Hansson, H. C.; Swietlicki, E.; Henzing, J. S.

    2014-05-13

    Many of the next generation of global climate models will include aerosol schemes which explicitly simulate the microphysical processes that determine the particle size distribution. These models enable aerosol optical properties and cloud condensation nuclei (CCN) concentrations to be determined by fundamental aerosol processes, which should lead to a more physically based simulation of aerosol direct and indirect radiative forcings. This study examines the global variation in particle size distribution simulated by twelve global aerosol microphysics models to quantify model diversity and to identify any common biases against observations. Evaluation against size distribution measurements from a new European network of aerosol supersites shows that the mean model agrees quite well with the observations at many sites on the annual mean, but there are some seasonal biases common to many sites. In particular, at many of these European sites, the accumulation mode number concentration is biased low during winter and Aitken mode concentrations tend to be overestimated in winter and underestimated in summer. At high northern latitudes, the models strongly underpredict Aitken and accumulation particle concentrations compared to the measurements, consistent with previous studies that have highlighted the poor performance of global aerosol models in the Arctic. In the marine boundary layer, the models capture the observed meridional variation in the size distribution, which is dominated by the Aitken mode at high latitudes, with an increasing concentration of accumulation particles with decreasing latitude. Considering vertical profiles, the models reproduce the observed peak in total particle concentrations in the upper troposphere due to new particle formation, although modelled peak concentrations tend to be biased high over Europe. Overall, the results suggest that most global aerosol microphysics models simulate the global variation of the particle size distribution

  3. Studying Precipitation Processes in WRF with Goddard Bulk Microphysics in Comparison with Other Microphysical Schemes

    NASA Technical Reports Server (NTRS)

    Tao, W.K.; Shi, J.J.; Braun, S.; Simpson, J.; Chen, S.S.; Lang, S.; Hong, S.Y.; Thompson, G.; Peters-Lidard, C.

    2009-01-01

    A Goddard bulk microphysical parameterization is implemented into the Weather Research and Forecasting (WRF) model. This bulk microphysical scheme has three different options, 2ICE (cloud ice & snow), 3ICE-graupel (cloud ice, snow & graupel) and 3ICE-hail (cloud ice, snow & hail). High-resolution model simulations are conducted to examine the impact of microphysical schemes on different weather events: a midlatitude linear convective system and an Atlantic hurricane. The results suggest that microphysics has a major impact on the organization and precipitation processes associated with a summer midlatitude convective line system. The Goddard 3ICE scheme with the cloud ice-snow-hail configuration agreed better with observations ill of rainfall intensity and having a narrow convective line than did simulations with the cloud ice-snow-graupel and cloud ice-snow (i.e., 2ICE) configurations. This is because the Goddard 3ICE-hail configuration has denser precipitating ice particles (hail) with very fast fall speeds (over 10 m/s) For an Atlantic hurricane case, the Goddard microphysical scheme (with 3ICE-hail, 3ICE-graupel and 2ICE configurations) had no significant impact on the track forecast but did affect the intensity slightly. The Goddard scheme is also compared with WRF's three other 3ICE bulk microphysical schemes: WSM6, Purdue-Lin and Thompson. For the summer midlatitude convective line system, all of the schemes resulted in simulated precipitation events that were elongated in southwest-northeast direction in qualitative agreement with the observed feature. However, the Goddard 3ICE-hail and Thompson schemes were closest to the observed rainfall intensities although the Goddard scheme simulated more heavy rainfall (over 48 mm/h). For the Atlantic hurricane case, none of the schemes had a significant impact on the track forecast; however, the simulated intensity using the Purdue-Lin scheme was much stronger than the other schemes. The vertical distributions of

  4. Analysis of aerosol optical and microphysical properties observed during the DC3 field study

    NASA Astrophysics Data System (ADS)

    Chen, G.; Schuster, G. L.; Anderson, B. E.; Jimenez, J. L.; Campuzano Jost, P.; Dibb, J. E.; Scheuer, E. M.; Ziemba, L. D.; Beyersdorf, A. J.; Thornhill, K. L.; Moore, R.; Winstead, E.; Markovic, M. Z.

    2013-12-01

    The Deep Convective Clouds and Chemistry Experiment (DC3) consisted of 18 research flights from Salina, KS. During cloud inflow and outflow surveys, various aged aerosol layers and plumes, including biomass burning, were sampled by the NASA DC-8 aircraft which was equipped with a broad suite of instruments for aerosol optical, microphysical, and chemical properties. As a result, the DC3 dataset includes detailed aerosol number size distribution, bulk aerosol mass concentration, black carbon mass concentration, and mass size distribution for sulfate, nitrate, ammonium and organics, together with scattering and absorption coefficients. We use this comprehensive dataset to perform a detailed closure analysis to examine the consistency between the observed aerosol properties and the literature reported aerosol refractive index values. In this context, we report aerosol observations, and comparisons between the aerosol mass and number size distribution for various aerosol layers. Closure tests will also be presented in terms of the impact of the aerosol composition and size distribution on the scattering and absorption.

  5. Systematic Relationships among Background SE U.S. Aerosol Optical, Micro-physical, and Chemical Properties-Development of an Optically-based Aerosol Characterization

    NASA Astrophysics Data System (ADS)

    Sherman, J. P.; Link, M. F.; Zhou, Y.

    2014-12-01

    Remote sensing-based retrievals of aerosol composition require known or assumed relationships between aerosol optical properties and types. Most optically-based aerosol classification schemes apply some combination of the spectral dependence of aerosol light scattering and absorption-using the absorption and either scattering or extinction Angstrom exponents (AAE, SAE and EAE), along with single-scattering albedo (SSA). These schemes can differentiate between such aerosol types as dust, biomass burning, and urban/industrial but no such studies have been conducted in the SE U.S., where a large fraction of the background aerosol is a variable mixture of biogenic SOA, sulfates, and black carbon. In addition, AERONET retrievals of SSA are often highly uncertain due to low AOD in the region during most months. The high-elevation, semi-rural AppalAIR facility at Appalachian State University in Boone, NC (1090m ASL, 36.210N, 81.690W) is home to the only co-located NOAA-ESRL and AERONET monitoring sites in the eastern U.S. Aerosol chemistry measured at AppalAIR is representative of the background SE U.S (Link et al. 2014) Dried aerosol light absorption and dried and humidified aerosol light scattering and hemispheric backscattering at 3 visible wavelengths and 2 particle size cuts (sub-1μm and sub-10μm) are measured continuously. Measurements of size-resolved, non-refractory sub-1μm aerosol composition were made by a co-located AMS during the 2012-2013 summers and 2013 winter. Systematic relationships among aerosol optical, microphysical, and chemical properties were developed to better understand aerosol sources and processes and for use in higher-dimension aerosol classification schemes. The hygroscopic dependence of visible light scattering is sensitive to the ratio of sulfate to organic aerosol(OA), as are SSA and AAE. SAE is a less sensitive indicator of fine-mode aerosol size than hemispheric backscatter fraction (b) and is more sensitive to fine-mode aerosol

  6. [Microphysics of atmospheric aerosols during winter haze/fog events in Nanjing].

    PubMed

    Yang, Jun; Niu, Zhong-qing; Shi, Chun-e; Liu, Duan-yang; Li, Zi-hua

    2010-07-01

    Intensive field observations of fog/haze events, including simultaneous measurements of aerosol particle and fog droplet size distributions, were conducted in Nanjing in November, 2007. Four weather conditions (fog, mist, wet haze and haze) were distinguished based on visibility and liquid water content firstly. Then, the microphysical characteristics of coarse and fine particles in each condition were investigated. The results showed the dominant sequence of the four weather conditions was haze<-->mist-->wet haze-->fog-->, wet haze-->mist<-->haze. The lasting time of pre-fog wet haze was longer than that of post-fog wet haze. The number, surface area and volume concentration of coarse particles with diameter larger than 2.0 micron in fog were much higher than those in the other three conditions, and the smallest concentrations were observed in haze. The size distributions of surface area and volume concentration exhibited multi-peak in fog droplets, while it showed single peak for coarse particles in haze, mist and wet haze. For the fine particles with diameter larger than 0.010 microm, the spectral shapes of surface area concentration are similar in fog (mist) and wet haze (haze) condition. The dominant size ranges of fine particle number concentration were in 0.04-0.13 microm and 0.02-0.14 microm for fog and wet haze, separately. The same dominant size ranges located in 0.02-0.06 microm for both mist and haze. During the transition processes from haze, mist and wet haze to fog, the concentration of smaller particles (less than 0.060-0.090 microm) reduced and vice versa for the corresponding larger particles. Temporal variation of aerosol number concentration correlated well with the root mean diameters negatively during the observation period. The number concentration of aerosol was the lowest and the mean diameter was the largest in fog periods.

  7. Retrievals of Aerosol and Cloud Particle Microphysics Using Polarization and Depolarization Techniques

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael; Hansen, James E. (Technical Monitor)

    2001-01-01

    The recent availability of theoretical techniques for computing single and multiple scattering of light by realistic polydispersions of spherical and nonspherical particles and the strong dependence of the Stokes scattering matrix on particle size, shape, and refractive index make polarization and depolarization measurements a powerful particle characterization tool. In this presentation I will describe recent applications of photopolarimetric and lidar depolarization measurements to remote sensing characterization of tropospheric aerosols, polar stratospheric clouds (PSCs), and contrails. The talk will include (1) a short theoretical overview of the effects of particle microphysics on particle single-scattering characteristics; (2) the use of multi-angle multi-spectral photopolarimetry to retrieve the optical thickness, size distribution, refractive index, and number concentration of tropospheric aerosols over the ocean surface; and (3) the application of the T-matrix method to constraining the PSC and contrail particle microphysics using multi-spectral measurements of lidar backscatter and depolarization.

  8. Simulation of transport and microphysical evolution of stratospheric aerosols by the MOSTRA model

    NASA Astrophysics Data System (ADS)

    Bingen, Christine; Errera, Quentin; Daerden, Frank; Chabrillat, Simon; Stapelle, Maxime; Vanhellemont, Filip; Dodion, Jan; Dekemper, Emmanuel; Fussen, Didier; Mateshvili, Nina; Loodts, Nicolas

    We present the current status of the development of a microphysical/transport model for stratospheric aerosols, called MOdel for STRatospheric Aerosols (MOSTRA). This model is a 4D 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). We will present the current status of the model development and the most recent results obtained by simulations using MOSTRA. 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.

  9. Aerosol and Cloud Microphysical Characteristics of Rifts and Gradients in Maritime Stratocumulus Clouds

    NASA Technical Reports Server (NTRS)

    Sharon, Tarah M.; Albrecht, Bruce A.; Jonsson, Haflidi H.; Minnis, Patrick; Khaiyer, Mandana M.; Van Reken, Timothy; Seinfeld, John; Flagan, Rick

    2008-01-01

    A cloud rift is characterized as a large-scale, persistent area of broken, low reflectivity stratocumulus clouds usually surrounded by a solid deck of stratocumulus. A rift observed off the coast of Monterey Bay, California on 16 July 1999 was studied to compare the aerosol and cloud microphysical properties in the rift with those of the surrounding solid stratus deck. Variables measured from an instrumented aircraft included temperature, water vapor, and cloud liquid water. These measurements characterized the thermodynamic properties of the solid deck and rift areas. Microphysical measurements made included aerosol, cloud drop and drizzle drop concentrations and cloud condensation nuclei (CCN) concentrations. The microphysical characteristics in a solid stratus deck differ substantially from those of a broken, cellular rift where cloud droplet concentrations are a factor of 2 lower than those in the solid cloud. Further, CCN concentrations were found to be about 3 times greater in the solid cloud area compared with those in the rift and aerosol concentrations showed a similar difference as well. Although drizzle was observed near cloud top in parts of the solid stratus cloud, the largest drizzle rates were associated with the broken clouds within the rift area. In addition to marked differences in particle concentrations, evidence of a mesoscale circulation near the solid cloud rift boundary is presented. This mesoscale circulation provides a mechanism for maintaining a rift, but further study is required to understand the initiation of a rift and the conditions that may cause it to fill.

  10. Impact of Aerosol Processing on Orographic Clouds

    NASA Astrophysics Data System (ADS)

    Pousse-Nottelmann, Sara; Zubler, Elias M.; Lohmann, Ulrike

    2010-05-01

    Aerosol particles undergo significant modifications during their residence time in the atmosphere. Physical processes like coagulation, coating and water uptake, and aqueous surface chemistry alter the aerosol size distribution and composition. At this, clouds play a primary role as physical and chemical processing inside cloud droplets contributes considerably to the changes in aerosol particles. A previous study estimates that on global average atmospheric particles are cycled three times through a cloud before being removed from the atmosphere [1]. An explicit and detailed treatment of cloud-borne particles has been implemented in the regional weather forecast and climate model COSMO-CLM. The employed model version includes a two-moment cloud microphysical scheme [2] that has been coupled to the aerosol microphysical scheme M7 [3] as described by Muhlbauer and Lohmann, 2008 [4]. So far, the formation, transfer and removal of cloud-borne aerosol number and mass were not considered in the model. Following the parameterization for cloud-borne particles developed by Hoose et al., 2008 [5], distinction between in-droplet and in-crystal particles is made to more physically account for processes in mixed-phase clouds, such as the Wegener-Bergeron-Findeisen process and contact and immersion freezing. In our model, this approach has been extended to allow for aerosol particles in five different hydrometeors: cloud droplets, rain drops, ice crystals, snow flakes and graupel. We account for nucleation scavenging, freezing and melting processes, autoconversion, accretion, aggregation, riming and selfcollection, collisions between interstitial aerosol particles and hydrometeors, ice multiplication, sedimentation, evaporation and sublimation. The new scheme allows an evaluation of the cloud cycling of aerosol particles by tracking the particles even when scavenged into hydrometeors. Global simulations of aerosol processing in clouds have recently been conducted by Hoose et al

  11. 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.

  12. 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.

  13. 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

  14. Investigation of warm-cloud microphysics using a multi-component cloud model: Interactive effects of the aerosol spectrum. Master's thesis

    SciTech Connect

    Zahn, S.G.

    1993-12-01

    Clouds, especially low, warm, boundary-layer clouds, play an important role in regulating the earth's climate due to their significant contribution to the global albedo. The radiative effects of individual clouds are controlled largely by cloud microstructure, which is itself sensitive to the concentration and spectral distribution of the atmospheric aerosol. Increases in aerosol particle concentrations from anthropogenic activity could result in increased cloud albedo and global cloudiness, increasing the amount of reflected solar radiation. However, the effects of increased aerosol particle concentrations could be offset by the presence of giant or ultragiant aerosol particles. A one-dimensional, multi-component microphysical cloud model has been used to demonstrate the effects of aerosol particle spectral variations on the microstructure of warm clouds. Simulations performed with this model demonstrate that the introduction of increased concentrations of giant aerosol particles has a destabilizing effect on the cloud microstructure. Also, it is shown that warm-cloud microphysical processes modify the aerosol particle spectrum, favoring the generation of the largest sized particles via the collision-coalescence process. These simulations provide further evidence that the effect of aerosol particles on cloud microstructure must be addressed when considering global climate forecasts.

  15. Micro-physical properties of carbonaceous aerosol particles generated by laser ablation of a graphite target

    NASA Astrophysics Data System (ADS)

    Ajtai, T.; Utry, N.; Pintér, M.; Tápai, Cs.; Kecskeméti, G.; Smausz, T.; Hopp, B.; Bozóki, Z.; Szabó, G.

    2014-09-01

    In this work the authors propose laser ablation as a highly versatile tool for carbonaceous aerosol generation. The generated carbonaceous particles can be used as a model aerosol for atmospheric black carbon. Various microphysical properties including mass concentration, size distribution and morphology of aerosol particles generated by laser ablation of a high purity graphite sample were investigated in detail. These measurements proved that the proposed method can be used to generate both primary particles and fractal aggregates with a high yield. As a further advantage of the method the size distribution of the generated aerosol can cover a wide range, and can be tuned accurately with laser fluence, the ambient composition or with the volumetric flow rate of the carrier gas.

  16. Microphysical effects determine macrophysical response for aerosol impacts on deep convective clouds

    PubMed Central

    Fan, Jiwen; Leung, L. Ruby; Rosenfeld, Daniel; Chen, Qian; Li, Zhanqing; Zhang, Jinqiang; Yan, Hongru

    2013-01-01

    Deep convective clouds (DCCs) play a crucial role in the general circulation, energy, and hydrological cycle of our climate system. Aerosol particles can influence DCCs by altering cloud properties, precipitation regimes, and radiation balance. Previous studies reported both invigoration and suppression of DCCs by aerosols, but few were concerned with the whole life cycle of DCC. By conducting multiple monthlong cloud-resolving simulations with spectral-bin cloud microphysics that capture the observed macrophysical and microphysical properties of summer convective clouds and precipitation in the tropics and midlatitudes, this study provides a comprehensive view of how aerosols affect cloud cover, cloud top height, and radiative forcing. We found that although the widely accepted theory of DCC invigoration due to aerosol’s thermodynamic effect (additional latent heat release from freezing of greater amount of cloud water) may work during the growing stage, it is microphysical effect influenced by aerosols that drives the dramatic increase in cloud cover, cloud top height, and cloud thickness at the mature and dissipation stages by inducing larger amounts of smaller but longer-lasting ice particles in the stratiform/anvils of DCCs, even when thermodynamic invigoration of convection is absent. The thermodynamic invigoration effect contributes up to ∼27% of total increase in cloud cover. The overall aerosol indirect effect is an atmospheric radiative warming (3–5 W⋅m−2) and a surface cooling (−5 to −8 W⋅m−2). The modeling findings are confirmed by the analyses of ample measurements made at three sites of distinctly different environments. PMID:24218569

  17. Alterations of Cloud Microphysics Due to Cloud Processed CCN

    NASA Astrophysics Data System (ADS)

    Hudson, J. G.; Tabor, S. S.; Noble, S. R., Jr.

    2015-12-01

    High-resolution CCN spectra have revealed bimodality (Hudson et al. 2015) similar to aerosol size spectra (e.g., Hoppel et al. 1985). Bimodality is caused by chemical and physical cloud processes that increase mass or hygroscopicity of only CCN that produced activated cloud droplets. Bimodality is categorized by relative CCN concentrations (NCCN) within the two modes, Nu-Np; i.e., NCCN within the higher critical supersaturation, Sc, mode that did not undergo cloud processing minus NCCN within the lower Sc mode that was cloud processed. Lower, especially negative, Nu-Np designates greater processing. The table shows regressions between Nu-Np and characteristics of clouds nearest the CCN measurements. ICE-T MASE parameter R SL R SL Nc 0.17 93.24 -0.26 98.65 MD -0.31 99.69 0.33 99.78 σ -0.27 99.04 0.48 100.00 Ld -0.31 99.61 0.38 99.96 Table. Correlation coefficients, R, and one-tailed significance levels in percent, SL, for Nu-Np with microphysics of the clouds closest to each CCN measurement, 75 ICE-T and 74 MASE cases. Nc is cloud droplet concentration, MD is cloud droplet mean diameter, σ is standard deviation of cloud droplet spectra, Ldis drizzle drop LWC. Two aircraft field campaigns, Ice in Clouds Experiment-Tropical (ICE-T) and Marine Stratus/Stratocumulus Experiment (MASE) show opposite R signs because coalescence dominated cloud processing in low altitude ICE-T cumuli whereas chemical transformations predominated in MASE low altitude polluted stratus. Coalescence reduces Nc and NCCN, which thus increases MD, and σ, which promote Ld. Chemical transformations, e.g., SO2 to SO4, increase CCN hygroscopicity, thus reducing Sc, but not affecting Nc or NCCN. Lower Sc CCN are capable of producing greater Nc in subsequent cloud cycles, which leads to lower MD and σ which reduce Ld (figure). These observations are consistent with cloud droplet growth models for the higher vertical wind (W) of cumuli and lower W of stratus. Coalescence thus reduces the indirect

  18. War Induced Aerosol Optical, Microphysical and Radiative Effects

    NASA Astrophysics Data System (ADS)

    Munshi, Pavel; Tiwari, Shubhansh

    2017-01-01

    The effect of war on air pollution and climate is assessed in this communication. War today in respect of civil wars and armed conflict in the Middle East area is taken into consideration. Impacts of war are not only in loss of human life and property, but also in the environment. It is well known that war effects air pollution and in the long run contribute to anthropogenic climate change, but general studies on this subject are few because of the difficulties of observations involved. In the current scenario of the ongoing conflict in the Middle East regions, deductions in parameters of atmosphere are discussed. Aerosol Optical Depth, Aerosol loads, Black Carbon, Ozone,Dust, regional haze and many more are analyzed using various satellite data. Multi-model analysis is also studied to verify the analysis. Type segregation of aerosols, in-depth constraints to atmospheric chemistry, biological effects and particularly atmospheric physics in terms of radiative forcing, etc. are discussed. Undergraduate in Earth Sciences.

  19. 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.

  20. 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.

  1. Probing the impact of different aerosol sources on cloud microphysics and precipitation through in-situ measurements of chemical mixing state

    NASA Astrophysics Data System (ADS)

    Prather, K. A.; Suski, K.; Cazorla, A.; Cahill, J. F.; Creamean, J.; Collins, D. B.; Heymsfield, A.; Roberts, G. C.; DeMott, P. J.; Sullivan, R. C.; Rosenfeld, D.; Comstock, J. M.; Tomlinson, J. M.

    2011-12-01

    Aerosol particles play a crucial role in affecting cloud processes by serving as cloud nuclei. However, our understanding of which particles actually form cloud and ice nuclei limits our ability to treat aerosols properly in climate models. In recent years, it has become possible to measure the chemical composition of individual cloud nuclei within the clouds using on-line mass spectrometry. In-situ high time resolution chemistry can now be compared with cloud physics measurements to directly probe the impact of aerosol chemistry on cloud microphysics. This presentation will describe results from two recent field campaigns, CalWater in northern California and ICE-T in the western Caribbean region. Ground-based and aircraft measurements will be presented of aerosol mixing state, cloud microphysics, and meteorology. Results from single particle mass spectrometry will show the sources of the cloud seeds, including dust, biomass burning, sea spray, and biological particles. Details will be provided on how we are now able to probe the sources and cycling of atmospheric aerosols by measuring individual aerosols, cloud nuclei, and precipitation chemistry. The important role of dust, both Asian and African, and bioparticles in forming ice nuclei will be discussed. Finally, a summary will be provided discussing how these new in-situ measurements are being used to advance our understanding of complex atmospheric processes, and improve our understanding of aerosol impacts on climate.

  2. Aerosol optical and microphysical properties from POLDER-PARASOL multi-angle photo-polarimetric measurements

    NASA Astrophysics Data System (ADS)

    Hasekamp, O.; Litvinov, P.; Butz, A.

    2010-12-01

    The large uncertainty on the aerosol effects on clouds and climate is reflected in considerable discrepancies between different model simulations of the radiative forcing caused by these effects. Also, there exist even larger differences between values for radiative forcing calculated by models and those estimated from satellites (and model calculations constrained by satellite measurements). Relationships between aerosols and clouds derived from satellite measurements are subject to a number of important limitations. First of all, with current satellite aerosol products it is hard to determine which fraction of the aerosols is anthropogenic and which fraction is natural. Often the rather crude assumption is used that the fine mode contribution is fully anthropogenic. Furthermore, most aerosol types are strongly hygroscopic, which means that in an environment with high relative humidity (in the surrounding of clouds) the particle size increases considerably leading, in turn, to an increase in optical thickness. This effect may be misinterpreted as an apparent relation between aerosol concentration and cloud cover. Also, meteorology effects can be misinterpreted as apparent aerosol-cloud relationships. Accurate information on aerosol size and refractive index (related to chemical composition of aerosols and absorption) is needed to distinguish between natural and anthropogenic aerosols and to distinguish between aerosol effects on cloud formation and apparent relationships due to humidity and meteorology effects. Multi-angle photopolarimetric measurements have the potential to provide the necessary information on these aerosol properties. The POLDER instrument onboard the PARASOL micro-satellite is the only instrument currently in space that performs multi-angle photopolarimetric measurements. To fully exploit the information contained in these measurements a new type of retrieval algorithm is needed that retrieves detailed information on aerosol microphysical and

  3. Sensitivity of Multiangle Imaging to the Optical and Microphysical Properties of Biomass Burning Aerosols

    NASA Technical Reports Server (NTRS)

    Chen, Wei-Ting; Kahn, Ralph A.; Nelson, David; Yau, Kevin; Seinfeld, John H.

    2008-01-01

    The treatment of biomass burning (BB) carbonaceous particles in the Multiangle Imaging SpectroRadiometer (MISR) Standard Aerosol Retrieval Algorithm is assessed, and algorithm refinements are suggested, based on a theoretical sensitivity analysis and comparisons with near-coincident AERONET measurements at representative BB sites. Over the natural ranges of BB aerosol microphysical and optical properties observed in past field campaigns, patterns of retrieved Aerosol Optical Depth (AOD), particle size, and single scattering albedo (SSA) are evaluated. On the basis of the theoretical analysis, assuming total column AOD of 0.2, over a dark, uniform surface, MISR can distinguish two to three groups in each of size and SSA, except when the assumed atmospheric particles are significantly absorbing (mid-visible SSA approx.0.84), or of medium sizes (mean radius approx.0.13 pin); sensitivity to absorbing, medium-large size particles increases considerably when the assumed column AOD is raised to 0.5. MISR Research Aerosol Retrievals confirm the theoretical results, based on coincident AERONET inversions under BB-dominated conditions. When BB is externally mixed with dust in the atmosphere, dust optical model and surface reflection uncertainties, along with spatial variability, contribute to differences between the Research Retrievals and AERONET. These results suggest specific refinements to the MISR Standard Aerosol Algorithm complement of component particles and mixtures. They also highlight the importance for satellite aerosol retrievals of surface reflectance characterization, with accuracies that can be difficult to achieve with coupled surface-aerosol algorithms in some higher AOD situations.

  4. 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.

  5. 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.

  6. A numerical study of aerosol effects on the dynamics and microphysics of a deep convective cloud in a continental environment

    NASA Astrophysics Data System (ADS)

    Cui, Zhiqiang; Carslaw, Kenneth S.; Yin, Yan; Davies, Stewart

    2006-03-01

    The effects of aerosols on a deep convective cloud in a midlatitude continental environment are studied using an axisymmetric cloud model with a sectional treatment of aerosol and hydrometeor microphysical processes. Simulations are conducted using observations from the Cooperative Convective Precipitation Experiments (CCOPE). The isolated cloud occurred in an environment with low wind shear and with relatively dry air in the midtroposphere and upper troposphere. By varying the concentration of aerosol particles in the accumulation mode within realistic limits for a continental environment, the simulated cloud exhibited different properties. The overall impact as the aerosol concentration increased is that (1) the cloud development was inhibited; (2) the precipitation was suppressed; (3) the maximum values of liquid water content decreased, but the maximum values of droplet number concentration increased before the dissipating stage; (4) a clear tendency was found for ice crystals to be larger and less numerous in the anvil cloud; and (5) there was a significant reduction of the inflow in the lower 2 km of the atmosphere. In the relatively dry environment in the midtroposphere, the latent heat changes associated with the Wegener-Bergeron-Findeisen mechanism played an important role in the upper part of the cloud at altitudes below the homogeneous freezing level. In particular, immersion freezing and latent heat release were much more rapid in the base simulation than in the increased aerosol simulation. Less latent heat release and insufficient inflow together impeded the development of the cloud with the higher aerosol loading. Our simulations suggest that continental clouds existing below the homogeneous freezing level could show an opposite response of cloud top height and anvil crystal concentrations to changes in aerosol to what has previously been reported for clouds ascending to higher levels.

  7. Microphysical and compositional influences on shortwave radiative forcing of climate by sulfate aerosols

    SciTech Connect

    Schwartz, S.E.; Wagener, R.; Nemesure, S.

    1995-02-01

    Anthropogenic sulfate aerosols scatter shortwave (solar) radiation iincident upon the atmosphere, thereby exerting a cooling influence on climate relative to pre-industrial times. Previous estimates of this forcing place its global and annual average value at about {minus}1 W M{sup {minus}2}, uncertain to a factor of somewhat more than 2, comparable in magnitude to greenhouse gas forcing over the same period but opposite in sign and much more uncertain. Key sources of uncertainty are atmospheric chemistry factors (yield, residence time), and microphysical factors (scattering efficiency, upscatter fraction, and the dependence of these quantities on particle size and relative humidity, RH). This paper examines these microphysical influences to indentify properties required to obtain more a accurate description of this forcing. The mass scattering efficiency exhibits a maximum at a particle diameter ({approximately}0.5 {mu}m) roughly equal to the wavelength of maximum power in the solar spectrum and roughly equal to diameter typical of anthropogenic sulfate aerosols. Particle size, and hence mass scattering efficiency, increase with increasing on RH because of accretion of water by deliquescent salt aerosols.

  8. Aerosol Impacts on Clouds and Precipitation in Eastern China: Results from Bin and Bulk Microphysics

    SciTech Connect

    Fan, Jiwen; Leung, Lai-Yung R.; Li, Zhanqing; Morrison, H.; Chen, Hongbin; Zhou, Yuquan; Qian, Yun; Wang, Yuan

    2012-01-19

    Using the Weather Research and Forecasting (WRF) model coupled with a 3 spectral-bin microphysics ('SBM') and measurements from the Atmospheric Radiation 4 Measurement (ARM) Mobile Facility field campaign in China (AMF-China), the authors 5 examine aerosol indirect effects (AIE) in the typical cloud regimes of the warm and cold 6 seasons in Southeast China: deep convective clouds (DCC) and stratus clouds (SC), 7 respectively. Comparisons with a two-moment bulk microphysics ('Bulk') are performed 8 to gain insights for improving bulk schemes in estimating AIE in weather and climate 9 simulations. For the first time, measurements of aerosol and cloud properties acquired in 10 China are used to evaluate model simulations to better understand AIE in China. It is 11 found that changes in cloud condensation nuclei (CCN) concentration significantly 12 change the timing of storms, the spatial and temporal distributions of precipitation, the 13 frequency distribution of precipitation rate, as well as cloud base and top heights for the 14 DCC, but not for the SC. CCN increase cloud droplet number (Nc) and mass 15 concentrations, decrease raindrop number concentration (Nr), and delay the onset of 16 precipitation. It is indicated much higher Nc and the opposite CCN effects on convection 17 and heavy rain with Bulk compared to SBM stem from the fixed CCN prescribed in Bulk. 18 CCN have a significant effect on ice microphysical properties with SBM but not Bulk 19 and different condensation/deposition freezing parameterizations employed could be the 20 main reason. This study provided insights to further improve the bulk scheme to better 21 account for aerosol-cloud interactions in regional and global climate simulations, which 22 will be the focus for a follow-on paper.

  9. Next generation aerosol-cloud microphysics for advanced high-resolution climate predictions

    SciTech Connect

    Bennartz, Ralf; Hamilton, Kevin P; Phillips, Vaughan T.J.; Wang, Yuqing; Brenguier, Jean-Louis

    2013-01-14

    The three top-level project goals are: -We proposed to develop, test, and run a new, physically based, scale-independent microphysical scheme for those cloud processes that most strongly affect greenhouse gas scenarios, i.e. warm cloud microphysics. In particular, we propsed to address cloud droplet activation, autoconversion, and accretion. -The new, unified scheme was proposed to be derived and tested using the University of Hawaii's IPRC Regional Atmospheric Model (iRAM). -The impact of the new parameterizations on climate change scenarios will be studied. In particular, the sensitivity of cloud response to climate forcing from increased greenhouse gas concentrations will be assessed.

  10. Microphysical and compositional influences on shortwave radiative forcing of climate by sulfate aerosols

    SciTech Connect

    Schwartz, S F; Wagener, Richard; Nemesure, S

    1995-01-01

    Anthropogenic sulfate aerosols scatter shortwave (solar) radiation incident upon the atmosphere, thereby exerting a cooling influence on climate relative to pre-industrial times. Previous estimates of this forcing place its global and annual average value at about -1 W m{sup -2}, uncertain to a factor of somewhat more than 2, comparable in magnitude to greenhouse gas forcing over the same period but opposite in sign and much more uncertain. Key sources of uncertainty are atmospheric chemistry factors (yield, residence time), and microphysical factors (scattering efficiency, upscatter fraction, and the dependence of these quantities on particle size and relative humidity, RH). This paper examines these microphysical influences to identify properties required to obtain more a accurate description of this forcing. The mass scattering efficiency exhibits a maximum at a particle diameter ({approximately}0.5 M) roughly equal to the wavelength of maximum power in the solar spectrum and roughly equal to diameter typical of anthropogenic sulfate aerosols. Particle size, and hence mass scattering efficiency, increase with increasing on RH because of accretion of water by deliquescent salt aerosols. For example the scattering efficiency of aqueous (NH{sub 4}){sub 2}SO{sub 4} (dry radius 0.2 {mu}m) increases from 8 to 80 m{sup 2}/g (SO{sub 4}{sup 2-}) as RH increases from 39 to 97%. The sensitivity of forcing to particle dry mass and relative humidity suggest the need to explicitly represent these properties if the sulfate aerosol forcing is to be accurately described in climate models.

  11. Assessment of microphysical and chemical factors of aerosols over seas of the Russian Artic Eastern Section

    NASA Astrophysics Data System (ADS)

    Golobokova, Liudmila; Polkin, Victor

    2014-05-01

    The newly observed kickoff of the Northern Route development drew serious attention to state of the Arctic Resource environment. Occurring climatic and environmental changes are more sensitively seen in polar areas in particular. Air environment control allows for making prognostic assessments which are required for planning hazardous environmental impacts preventive actions. In August - September 2013, RV «Professor Khlustin» Northern Sea Route expeditionary voyage took place. En-route aerosol sampling was done over the surface of the Beringov, Chukotka and Eastern-Siberia seas (till the town of Pevek). The purpose of sampling was to assess spatio-temporal variability of optic, microphysical and chemical characteristics of aerosol particles of the surface layer within different areas adjacent to the Northern Sea Route. Aerosol test made use of automated mobile unit consisting of photoelectric particles counter AZ-10, aetalometr MDA-02, aspirator on NBM-1.2 pump chassis, and the impactor. This set of equipment allows for doing measurements of number concentration, dispersed composition of aerosols within sizes d=0.3-10 mkm, mass concentration of submicron sized aerosol, and filter-conveyed aerosols sampling. Filter-conveyed aerosols sampling was done using method accepted by EMEP and EANET monitoring networks. The impactor channel was upgraded to separate particles bigger than 1 mkm in size, and the fine grain fraction settled down on it. Reverse 5-day and 10-day trajectories of air mass transfer executed at heights of 10, 1500 and 3500 m were analyzed. The heights were selected by considerations that 3000 m is the height which characterizes air mass trend in the lower troposphere. 1500 m is the upper border of the atmospheric boundary layer, and the sampling was done in the Earth's surface layer at less than 10 m. Minimum values of the bespoken microphysical characteristics are better characteristic of higher latitudes where there are no man induced sources of

  12. A new approach to modeling aerosol effects on East Asian climate: Parametric uncertainties associated with emissions, cloud microphysics, and their interactions: AEROSOL EFFECTS ON EAST ASIAN CLIMATE

    SciTech Connect

    Yan, Huiping; Qian, Yun; Zhao, Chun; Wang, Hailong; Wang, Minghuai; Yang, Ben; Liu, Xiaohong; Fu, Qiang

    2015-09-09

    In this study, we adopt a parametric sensitivity analysis framework that integrates the quasi-Monte Carlo parameter sampling approach and a surrogate model to examine aerosol effects on the East Asian Monsoon climate simulated in the Community Atmosphere Model (CAM5). A total number of 256 CAM5 simulations are conducted to quantify the model responses to the uncertain parameters associated with cloud microphysics parameterizations and aerosol (e.g., sulfate, black carbon (BC), and dust) emission factors and their interactions. Results show that the interaction terms among parameters are important for quantifying the sensitivity of fields of interest, especially precipitation, to the parameters. The relative importance of cloud-microphysics parameters and emission factors (strength) depends on evaluation metrics or the model fields we focused on, and the presence of uncertainty in cloud microphysics imposes an additional challenge in quantifying the impact of aerosols on cloud and climate. Due to their different optical and microphysical properties and spatial distributions, sulfate, BC, and dust aerosols have very different impacts on East Asian Monsoon through aerosol-cloud-radiation interactions. The climatic effects of aerosol do not always have a monotonic response to the change of emission factors. The spatial patterns of both sign and magnitude of aerosol-induced changes in radiative fluxes, cloud, and precipitation could be different, depending on the aerosol types, when parameters are sampled in different ranges of values. We also identify the different cloud microphysical parameters that show the most significant impact on climatic effect induced by sulfate, BC and dust, respectively, in East Asia.

  13. Spatial and temporal CCN variations in convection-permitting aerosol microphysics simulations in an idealised marine tropical domain

    NASA Astrophysics Data System (ADS)

    Planche, Céline; Mann, Graham W.; Carslaw, Kenneth S.; Dalvi, Mohit; Marsham, John H.; Field, Paul R.

    2017-03-01

    changes in the vertical and at different points in the spin-up, showing how CCN concentrations are introduced both by the emissions close to the surface and at higher altitudes during strong wind-speed conditions associated to the intense convective period. We also explore how the non-linear variation of sea-salt emissions with wind speed propagates into variations in sea-salt mass mixing ratio and CCN concentrations, finding less variation in the latter two quantities due to the longer transport timescales inherent with finer CCN, which sediment more slowly. The complex mix of sources and diverse community of processes involved makes sub-grid parameterisation of CCN variations difficult. However, the results presented here illustrate the limitations of predictions with large-scale models and the high-resolution aerosol microphysics-dynamics modelling system shows promise for future studies where the aerosol variations will propagate through to modified cloud microphysical evolution.

  14. Aerosol optical, microphysical and radiative properties at regional background insular sites in the western Mediterranean

    NASA Astrophysics Data System (ADS)

    Sicard, Michaël; Barragan, Rubén; Dulac, François; Alados-Arboledas, Lucas; Mallet, Marc

    2016-09-01

    In the framework of the ChArMEx (the Chemistry-Aerosol Mediterranean Experiment; http://charmex.lsce.ipsl.fr/) program, the seasonal variability of the aerosol optical, microphysical and radiative properties derived from AERONET (Aerosol Robotic Network; http://aeronet.gsfc.nasa.gov/) is examined in two regional background insular sites in the western Mediterranean Basin: Ersa (Corsica Island, France) and Palma de Mallorca (Mallorca Island, Spain). A third site, Alborán (Alborán Island, Spain), with only a few months of data is considered for examining possible northeast-southwest (NE-SW) gradients of the aforementioned aerosol properties. The AERONET dataset is exclusively composed of level 2.0 inversion products available during the 5-year period 2011-2015. AERONET solar radiative fluxes are compared with ground- and satellite-based flux measurements. To the best of our knowledge this is the first time that AERONET fluxes are compared with measurements at the top of the atmosphere. Strong events (with an aerosol optical depth at 440 nm greater than 0.4) of long-range transport aerosols, one of the main drivers of the observed annual cycles and NE-SW gradients, are (1) mineral dust outbreaks predominant in spring and summer in the north and in summer in the south and (2) European pollution episodes predominant in autumn. A NE-SW gradient exists in the western Mediterranean Basin for the aerosol optical depth and especially its coarse-mode fraction, which all together produces a similar gradient for the aerosol direct radiative forcing. The aerosol fine mode is rather homogeneously distributed. Absorption properties are quite variable because of the many and different sources of anthropogenic particles in and around the western Mediterranean Basin: North African and European urban areas, the Iberian and Italian peninsulas, most forest fires and

  15. The effect of mineral dust and soot aerosols on ice microphysics near the foothills of the Himalayas: A numerical investigation

    NASA Astrophysics Data System (ADS)

    Hazra, Anupam; Padmakumari, B.; Maheskumar, R. S.; Chen, Jen-Ping

    2016-05-01

    This study investigates the influence of different ice nuclei (IN) species and their number concentrations on cloud ice production. The numerical simulation with different species of ice nuclei is investigated using an explicit bulk-water microphysical scheme in a Mesoscale Meteorological Model version 5 (MM5). The species dependent ice nucleation parameterization that is based on the classical nucleation theory has been implemented into the model. The IN species considered include dust and soot with two different concentrations (Low and High). The simulated cloud microphysical properties like droplet number concentration and droplet effective radii as well as macro-properties (equivalent potential temperature and relative humidity) are comparable with aircraft observations. When higher dust IN concentrations are considered, the simulation results showed good agreement with the cloud ice and cloud water mixing ratio from aircraft measurements during Cloud Aerosol Interactions and Precipitation Enhancement Experiment (CAIPEEX) and Modern Era Retrospective Analysis for Research and Applications (MERRA) reanalysis. Relative importance of IN species is shown as compared to the homogeneous freezing nucleation process. The tendency of cloud ice production rates is also analyzed and found that dust IN is more efficient in producing cloud ice when compared to soot IN. The dust IN with high concentration can produce more surface precipitation than soot IN at the same concentration. This study highlights the need to improve the ice nucleation parameterization in numerical models.

  16. The chemical and microphysical properties of secondary organic aerosols from Holm Oak emissions

    NASA Astrophysics Data System (ADS)

    Lang-Yona, N.; Rudich, Y.; Mentel, Th. F.; Bohne, A.; Buchholz, A.; Kiendler-Scharr, A.; Kleist, E.; Spindler, C.; Tillmann, R.; Wildt, J.

    2010-08-01

    The Mediterranean region is expected to experience substantial climatic change in the next 50 years. But, possible effects of climate change on biogenic volatile organic compound (VOC) emissions as well as on the formation of secondary organic aerosols (SOA) produced from these VOC are yet unexplored. To address such issues, the effects of temperature on the VOC emissions of Mediterranean Holm Oak and small Mediterranean stand of Wild Pistacio, Aleppo Pine, and Palestine Oak have been studied in the Jülich plant aerosol atmosphere chamber. For Holm Oak the optical and microphysical properties of the resulting SOA were investigated. Monoterpenes dominated the VOC emissions from Holm Oak (97.5%) and Mediterranean stand (97%). Higher temperatures enhanced the overall VOC emission but with different ratios of the emitted species. The amount of SOA increased linearly with the emission strength with a fractional mass yield of 6.0±0.6%, independent of the detailed emission pattern. The investigated particles were highly scattering with no absorption abilities. Their average hygroscopic growth factor of 1.13±0.03 at 90% RH with a critical diameter of droplet activation was 100±4 nm at a supersaturation of 0.4%. All microphysical properties did not depend on the detailed emission pattern, in accordance with an invariant O/C ratio (0.57(+0.03/-0.1)) of the SOA observed by high resolution aerosol mass spectrometry. The increase of Holm oak emissions with temperature (≈20% per degree) was stronger than e.g. for Boreal tree species (≈10% per degree). The SOA yield for Mediterranean trees determined here is similar as for Boreal trees. Increasing mean temperature in Mediterranean areas could thus have a stronger impact on BVOC emissions and SOA formation than in areas with Boreal forests.

  17. Simulation of the effects of aerosol on mixed-phase orographic clouds using the WRF model with a detailed bin microphysics scheme

    NASA Astrophysics Data System (ADS)

    Xiao, Hui; Yin, Yan; Jin, Lianji; Chen, Qian; Chen, Jinghua

    2015-08-01

    The Weather Research Forecast (WRF) mesoscale model coupled with a detailed bin microphysics scheme is used to investigate the impact of aerosol particles serving as cloud condensation nuclei and ice nuclei on orographic clouds and precipitation. A mixed-phase orographic cloud developed under two scenarios of aerosol (a typical continental background and a relatively polluted urban condition) and ice nuclei over an idealized mountain is simulated. The results show that, when the initial aerosol condition is changed from the relatively clean case to the polluted scenario, more droplets are activated, leading to a delay in precipitation, but the precipitation amount over the terrain is increased by about 10%. A detailed analysis of the microphysical processes indicates that ice-phase particles play an important role in cloud development, and their contribution to precipitation becomes more important with increasing aerosol particle concentrations. The growth of ice-phase particles through riming and Wegener-Bergeron-Findeisen regime is more effective under more polluted conditions, mainly due to the increased number of droplets with a diameter of 10-30 µm. Sensitivity tests also show that a tenfold increase in the concentration of ice crystals formed from ice nucleation leads to about 7% increase in precipitation, and the sensitivity of the precipitation to changes in the concentration and size distribution of aerosol particles is becoming less pronounced when the concentration of ice crystals is also increased.

  18. Sensitivity of thermal infrared sounders to the chemical and micro-physical properties of UTLS secondary sulphate aerosols

    NASA Astrophysics Data System (ADS)

    Sellitto, P.; Legras, B.

    2015-08-01

    Monitoring upper tropospheric-lower stratospheric (UTLS) secondary sulphate aerosols and their chemical and micro-physical properties from satellite nadir observations is crucial to better understand their formation and evolution processes and then to estimate their impact to the UTLS chemistry, and on regional and global radiative balance. Here we present a study aimed at the evaluation of the sensitivity of thermal infrared (TIR) satellite nadir observations to the chemical composition and the size distribution of idealized UTLS sulphate aerosol layers. The extinction properties of sulphuric acid/water droplets, for different sulphuric acid mixing ratios and temperatures, are systematically analysed. The extinction coefficients are derived by means of a Mie code, using refractive indexes taken from the GEISA (Gestion et Étude des Informations Spectroscopiques Atmosphériques: Management and Study of Spectroscopic Information) spectroscopic database and log-normal size distributions with different effective radii and number concentrations. IASI (Infrared Atmospheric Sounding Interferometer) pseudo-observations are generated using forward radiative transfer calculations performed with the 4A (Automatized Atmospheric Absorption Atlas) radiative transfer model, to estimate the impact of the extinction of idealized aerosol layers, at typical UTLS conditions, on the brightness temperature spectra observed by this satellite instrument. We found a marked and typical spectral signature of these aerosol layers between 700 and 1200 cm-1, due to the absorption bands of the sulphate and bi-sulphate ions and the undissociated sulphuric acid, with the main absorption peaks at 1170 and 905 cm-1. The dependence of the aerosol spectral signature to the sulphuric acid mixing ratio, and effective number concentration and radius, as well as the role of interferring parameters like the ozone, sulphur dioxide, carbon dioxide and ash absorption, and temperature and water vapour profile

  19. Summary of long-term data on latitudinal dependence of the near-water aerosol microphysical characteristics in eastern Atlantic

    NASA Astrophysics Data System (ADS)

    Pol'kin, Viktor V.; Sakerin, Sergey M.; Pol'kin, Vasily V.; Turchinovich, Ury S.; Terpugova, Swetlana A.; Tikhomirov, Aleksey B.; Radionov, Vladimir F.

    2015-11-01

    Latitudinal dependences of aerosol microphysical characteristics are analyzed. The data were obtained in the Russian Antarctic Expedition (RAE) onboard the expedition vessels "Akademik Fedorov" and "Akademik Treshnikov" in 2006- 2014, as well as the research vessel "Akademik Sergey Vavilov" in 2004.

  20. Summer-winter differences in the relationships among background southeastern U.S. aerosol optical, micro-physical, and chemical properties

    NASA Astrophysics Data System (ADS)

    Sherman, J. P.; Link, M.; Zhou, Y.

    2015-12-01

    Relationships among aerosol optical, micro-physical, and chemical properties are useful for evaluating regional climate models, developing satellite-based aerosol retrievals, and understanding aerosol sources and processes. Since aerosol loading and optical properties vary primarily on seasonal scales in the southeastern U.S., it is important that such studies be carried out over multiple seasons but few (if any) such multi-season studies have been conducted in the region. The high-elevation, semi-rural AppalAIR facility at Appalachian State University in Boone, NC (1080m ASL, 36.210N, 81.690W) is home to the only co-located NOAA-ESRL and AERONET monitoring sites in the eastern U.S. Measurements of size-resolved, non-refractory sub-1μm aerosol composition were also made by a co-located AMS during the 2012-2013 summers and 2013 winter. Systematic relationships among aerosol optical, microphysical, and chemical properties were developed to better understand aerosol sources and processes and for use in higher-dimension aerosol classification schemes. Some of the major findings will be presented. Higher values of lower tropospheric aerosol light scattering coefficient at 550nm (a proxy for aerosol loading) are associated with higher single-scattering albedo (SSA) and lower hemispheric backscatter fraction (b) during both summer and winter. Absorption Angstrom exponent (AAE) is typically well under 1 during summer and near 1.3-1.4 during winter. Lowest summer AAE values coincide with large, highly-reflective particles and higher aerosol light scattering coefficient but summer AAE is only weakly anti-correlated with organic and sulfate mass concentrations. Winter AAE is consistent with a mixture of elemental carbon and light-absorbing organic carbon, possibly influenced by regional residential wood-burning during winter. The hygroscopic dependence of visible light scattering is sensitive to sulfate and organic aerosol mass fractions during both summer and winter

  1. Aerosol Impacts on Microphysical and Radiative Properties of Stratocumulus Clouds in the Southeast Pacific

    NASA Astrophysics Data System (ADS)

    Twohy, C. H.; Toohey, D. W.; Andrejczuk, M.; Anderson, J. R.; Adams, A.; Lytle, M.; George, R.; Wood, R.; Zuidema, P.; Leon, D.

    2011-12-01

    particle sizes, down to at least 55 nm in size, act as droplet nuclei in these stratocumulus clouds. A detailed LES microphysical model was used to show this can occur without invoking differences in chemical composition. Aerosol number concentration in the >0.05 and >0.1 μm size ranges was correlated with droplet number concentration, and anti-correlated with droplet effective radius, and the effect is statistically significant. The impact of aerosol pollutants was to increase droplet number and decrease droplet size within a region extending about 1000 km offshore. Cloud droplets were more numerous and smaller near shore, and there was less drizzle. However, MODIS satellite measurements were used to show that despite the smaller droplets near shore, cloud albedo is not higher near shore than offshore. This is due to the generally thinner clouds and lower liquid water path near shore.

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

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoguang; Wang, Jun

    2015-07-01

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

  3. Information content and sensitivity of the 3β + 2α lidar measurement system for aerosol microphysical retrievals

    NASA Astrophysics Data System (ADS)

    Burton, Sharon P.; Chemyakin, Eduard; Liu, Xu; Knobelspiesse, Kirk; Stamnes, Snorre; Sawamura, Patricia; Moore, Richard H.; Hostetler, Chris A.; Ferrare, Richard A.

    2016-11-01

    There is considerable interest in retrieving profiles of aerosol effective radius, total number concentration, and complex refractive index from lidar measurements of extinction and backscatter at several wavelengths. The combination of three backscatter channels plus two extinction channels (3β + 2α) is particularly important since it is believed to be the minimum configuration necessary for the retrieval of aerosol microphysical properties and because the technological readiness of lidar systems permits this configuration on both an airborne and future spaceborne instrument. The second-generation NASA Langley airborne High Spectral Resolution Lidar (HSRL-2) has been making 3β + 2α measurements since 2012. The planned NASA Aerosol/Clouds/Ecosystems (ACE) satellite mission also recommends the 3β + 2α combination.Here we develop a deeper understanding of the information content and sensitivities of the 3β + 2α system in terms of aerosol microphysical parameters of interest. We use a retrieval-free methodology to determine the basic sensitivities of the measurements independent of retrieval assumptions and constraints. We calculate information content and uncertainty metrics using tools borrowed from the optimal estimation methodology based on Bayes' theorem, using a simplified forward model look-up table, with no explicit inversion. The forward model is simplified to represent spherical particles, monomodal log-normal size distributions, and wavelength-independent refractive indices. Since we only use the forward model with no retrieval, the given simplified aerosol scenario is applicable as a best case for all existing retrievals in the absence of additional constraints. Retrieval-dependent errors due to mismatch between retrieval assumptions and true atmospheric aerosols are not included in this sensitivity study, and neither are retrieval errors that may be introduced in the inversion process. The choice of a simplified model adds clarity to the

  4. Retrievals of aerosol optical and microphysical properties from Imaging Polar Nephelometer scattering measurements

    NASA Astrophysics Data System (ADS)

    Reed Espinosa, W.; Remer, Lorraine A.; Dubovik, Oleg; Ziemba, Luke; Beyersdorf, Andreas; Orozco, Daniel; Schuster, Gregory; Lapyonok, Tatyana; Fuertes, David; Vanderlei Martins, J.

    2017-03-01

    A method for the retrieval of aerosol optical and microphysical properties from in situ light-scattering measurements is presented and the results are compared with existing measurement techniques. The Generalized Retrieval of Aerosol and Surface Properties (GRASP) is applied to airborne and laboratory measurements made by a novel polar nephelometer. This instrument, the Polarized Imaging Nephelometer (PI-Neph), is capable of making high-accuracy field measurements of phase function and degree of linear polarization, at three visible wavelengths, over a wide angular range of 3 to 177°. The resulting retrieval produces particle size distributions (PSDs) that agree, within experimental error, with measurements made by commercial optical particle counters (OPCs). Additionally, the retrieved real part of the refractive index is generally found to be within the predicted error of 0.02 from the expected values for three species of humidified salt particles, with a refractive index that is well established. The airborne measurements used in this work were made aboard the NASA DC-8 aircraft during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) field campaign, and the inversion of this data represents the first aerosol retrievals of airborne polar nephelometer data. The results provide confidence in the real refractive index product, as well as in the retrieval's ability to accurately determine PSD, without assumptions about refractive index that are required by the majority of OPCs.

  5. RACORO aerosol data processing

    SciTech Connect

    Elisabeth Andrews

    2011-10-31

    The RACORO aerosol data (cloud condensation nuclei (CCN), condensation nuclei (CN) and aerosol size distributions) need further processing to be useful for model evaluation (e.g., GCM droplet nucleation parameterizations) and other investigations. These tasks include: (1) Identification and flagging of 'splash' contaminated Twin Otter aerosol data. (2) Calculation of actual supersaturation (SS) values in the two CCN columns flown on the Twin Otter. (3) Interpolation of CCN spectra from SGP and Twin Otter to 0.2% SS. (4) Process data for spatial variability studies. (5) Provide calculated light scattering from measured aerosol size distributions. Below we first briefly describe the measurements and then describe the results of several data processing tasks that which have been completed, paving the way for the scientific analyses for which the campaign was designed. The end result of this research will be several aerosol data sets which can be used to achieve some of the goals of the RACORO mission including the enhanced understanding of cloud-aerosol interactions and improved cloud simulations in climate models.

  6. Aerosol microphysics simulations of the Mt. Pinatubo eruption with the UKCA composition-climate model

    NASA Astrophysics Data System (ADS)

    Dhomse, S. S.; Emmerson, K. M.; Mann, G. W.; Bellouin, N.; Carslaw, K. S.; Chipperfield, M. P.; Hommel, R.; Abraham, N. L.; Telford, P.; Braesicke, P.; Dalvi, M.; Johnson, C. E.; O'Connor, F.; Morgenstern, O.; Pyle, J. A.; Deshler, T.; Zawodny, J. M.; Thomason, L. W.

    2014-01-01

    We have enhanced the capability of a microphysical aerosol-chemistry module to simulate the atmospheric aerosol and precursor gases for both tropospheric and stratospheric conditions. Using the Mount Pinatubo eruption (June 1991) as a test case, we evaluate simulated aerosol properties in a composition-climate model against a range of satellite and in-situ observations. Simulations are performed assuming an injection of 20 Tg SO2 at 19-27 km in tropical latitudes, without any radiative feedback from the simulated aerosol. In both quiescent and volcanically perturbed conditions, simulated aerosol properties in the lower stratosphere show reasonable agreement with the observations. The model captures the observed timing of the maximum aerosol optical depth (AOD) and its decay timescale in both tropics and Northern Hemisphere (NH) mid-latitudes. There is also good qualitative agreement with the observations in terms of spatial and temporal variation of the aerosol effective radius (Reff), which peaks 6-8 months after the eruption. However, the model shows significant biases against some observational data sets. Simulated AOD and Surface Area Density (SAD) in the tropics are substantially higher than the gap-filled satellite data products during the first 6 months after the eruption. The model shows consistently weaker enhancement in Reff compared to satellite and in-situ measurements. Simulated aerosol particle size distribution is also compared to NH mid-latitude in-situ balloon sounding measurements of size-resolved number concentrations. Before the eruption, the model captures the observed profiles of lower stratospheric particle number concentrations with radii larger than 5, 150 and 250 nm (N5, N150 and N250) very well. However, in the first 6 months after the eruption, the model shows high bias in N5 concentrations in the lower stratosphere, suggesting too strong nucleation. Following particle growth via condensation and coagulation, this bias in the finest

  7. Optical and microphysical properties of mineral dust and biomass burning aerosol observed over Warsaw on 10th July 2013

    NASA Astrophysics Data System (ADS)

    Janicka, Lucja; Stachlewska, Iwona; Veselovskii, Igor; Baars, Holger

    2016-04-01

    Biomass burning aerosol originating from Canadian forest fires was widely observed over Europe in July 2013. Favorable weather conditions caused long-term westward flow of smoke from Canada to Western and Central Europe. During this period, PollyXT lidar of the University of Warsaw took wavelength dependent measurements in Warsaw. On July 10th short event of simultaneous advection of Canadian smoke and Saharan dust was observed at different altitudes over Warsaw. Different origination of both air masses was indicated by backward trajectories from HYSPLIT model. Lidar measurements performed with various wavelength (1064, 532, 355 nm), using also Raman and depolarization channels for VIS and UV allowed for distinguishing physical differences of this two types of aerosols. Optical properties acted as input for retrieval of microphysical properties. Comparisons of microphysical and optical properties of biomass burning aerosols and mineral dust observed will be presented.

  8. Microphysical properties of transported biomass burning aerosols in coastal regions, and application to improving retrievals of aerosol optical depth from SeaWiFS data

    NASA Astrophysics Data System (ADS)

    Sayer, A. M.; Hsu, N. C.; Bettenhausen, C.

    2013-05-01

    Due to the limited measurement capabilities of heritage and current spaceborne passive imaging radiometers, algorithms for the retrieval of aerosol optical depth (AOD) and related quantities must make assumptions relating to aerosol microphysical properties and surface reflectance. Over the ocean, surface reflectance can be relatively well-modelled, but knowledge of aerosol properties can remain elusive. Several field campaigns and many studies have examined the microphysical properties of biomass burning (smoke) aerosol. However, these largely focus on properties over land and near to the source regions. In coastal and open-ocean regions the properties of transported smoke may differ, due to factors such as aerosol aging, wet/dry deposition, and mixture with other aerosol sources (e.g. influence of maritime, pollution, or mineral dust aerosols). Hence, models based on near-source aerosol observations may be less representative of such transported smoke aerosols, introducing additional uncertainty into satellite retrievals of aerosol properties. This study examines case studies of transported smoke from select globally-distributed coastal and island Aerosol Robotic Network (AERONET) sites. These are used to inform improved models for over-ocean transported smoke aerosol for AOD retrievals from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS). These models are used in an updated version of the SeaWiFS Ocean Aerosol Retrieval (SOAR) algorithm, which has been combined with the Deep Blue algorithm over land to create a 13-year (1997-2010) high-quality record of AOD over land and ocean. Applying these algorithms to other sensors will enable the creation of a long-term global climate data record of spectral AOD.

  9. Profiling aerosol optical, microphysical and hygroscopic properties in ambient conditions by combining in situ and remote sensing

    NASA Astrophysics Data System (ADS)

    Tsekeri, Alexandra; Amiridis, Vassilis; Marenco, Franco; Nenes, Athanasios; Marinou, Eleni; Solomos, Stavros; Rosenberg, Phil; Trembath, Jamie; Nott, Graeme J.; Allan, James; Le Breton, Michael; Bacak, Asan; Coe, Hugh; Percival, Carl; Mihalopoulos, Nikolaos

    2017-01-01

    We present the In situ/Remote sensing aerosol Retrieval Algorithm (IRRA) that combines airborne in situ and lidar remote sensing data to retrieve vertical profiles of ambient aerosol optical, microphysical and hygroscopic properties, employing the ISORROPIA II model for acquiring the particle hygroscopic growth. Here we apply the algorithm on data collected from the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 research aircraft during the ACEMED campaign in the Eastern Mediterranean. Vertical profiles of aerosol microphysical properties have been derived successfully for an aged smoke plume near the city of Thessaloniki with aerosol optical depth of ˜ 0.4 at 532 nm, single scattering albedos of ˜ 0.9-0.95 at 550 nm and typical lidar ratios for smoke of ˜ 60-80 sr at 532 nm. IRRA retrieves highly hydrated particles above land, with 55 and 80 % water volume content for ambient relative humidity of 80 and 90 %, respectively. The proposed methodology is highly advantageous for aerosol characterization in humid conditions and can find valuable applications in aerosol-cloud interaction schemes. Moreover, it can be used for the validation of active space-borne sensors, as is demonstrated here for the case of CALIPSO.

  10. Combined aerosol in-situ measurements during the SALTRACE field experiment for the investigation of Saharan mineral dust microphysical and CCN properties and their spatial-temporal evolution during trans-Atlantic long-range transport

    NASA Astrophysics Data System (ADS)

    Walser, Adrian; Dollner, Maximilian; Sauer, Daniel; Weinzierl, Bernadett

    2015-04-01

    The Saharan Aerosol Long-range Transport and Aerosol-Cloud-Interaction Experiment (SALTRACE) was a field experiment conducted in June/July 2013, which aimed to investigate the transport and modification of Saharan mineral dust from the Sahara across the Atlantic Ocean to the Caribbean. In addition to ground-based measurements and satellite remote sensing, the DLR Falcon research aircraft was equipped with a number of aerosol in-situ instruments to gain direct information on the properties of airborne aerosol such as size distributions, microphysical, optical and cloud-condensation nuclei (CCN) properties. For the first time, several outbreaks of Saharan dust were probed with the same airborne instrumentation on both sides of the Atlantic. During transport, various processes may take place that modify the aerosol composition. Dry and wet deposition lead to a size-dependent aerosol removal. In case of wet deposition, the removal additionally depends on the particle's ability to act as CCN. Processes in the aqueous phase in subsequently re-evaporating cloud droplets can further alter microphysical and CCN properties of re-released particles. All resulting changes in the size distribution and particle properties impact the radiative feedback and CCN activity of the aged aerosol. This study aims to use combined airborne in-situ measurements to retrieve and compare vertically resolved aerosol size distributions, microphysical and CCN properties for both, short-range transported Saharan dust in the Cape Verde region and long-range transported dust in the Caribbean. We use this data to investigate the influence of long-range transport and associated processes on those properties. We will present vertical profiles of size-resolved aerosol concentrations and volatile fractions as well as CCN activated fractions and draw conclusions for aerosol mixing state, CCN activation diameters and particle hygroscopicities. We will discuss differences in vertical profiles and

  11. Development of an aerosol microphysical module: Aerosol Two-dimensional bin module for foRmation and Aging Simulation (ATRAS)

    SciTech Connect

    Matsui, H.; Koike, Makoto; Kondo, Yutaka; Fast, Jerome D.; Takigawa, M.

    2014-09-30

    Number concentrations, size distributions, and mixing states of aerosols are essential parameters for accurate estimation of aerosol direct and indirect effects. In this study, we developed an aerosol module, designated Aerosol Two-dimensional bin module for foRmation and Aging Simulation (ATRAS), that can represent these parameters explicitly by considering new particle formation (NPF), black carbon (BC) aging, and secondary organic aerosol (SOA) processes. A two-dimensional bin representation is used for particles with dry diameters from 40 nm to 10 µm to resolve both aerosol size (12 bins) and BC mixing state (10 bins) for a total of 120 bins. The particles with diameters from 1 to 40 nm are resolved using an additional 8 size bins to calculate NPF. The ATRAS module was implemented in the WRF-chem model and applied to examine the sensitivity of simulated mass, number, size distributions, and optical and radiative parameters of aerosols to NPF, BC aging and SOA processes over East Asia during the spring of 2009. BC absorption enhancement by coating materials was about 50% over East Asia during the spring, and the contribution of SOA processes to the absorption enhancement was estimated to be 10 – 20% over northern East Asia and 20 – 35% over southern East Asia. A clear north-south contrast was also found between the impacts of NPF and SOA processes on cloud condensation nuclei (CCN) concentrations: NPF increased CCN concentrations at higher supersaturations (smaller particles) over northern East Asia, whereas SOA increased CCN concentrations at lower supersaturations (larger particles) over southern East Asia. Application of ATRAS to East Asia also showed that the impact of each process on each optical and radiative parameter depended strongly on the process and the parameter in question. The module can be used in the future as a benchmark model to evaluate the accuracy of simpler aerosol models and examine interactions between NPF, BC aging, and SOA

  12. Development of an aerosol microphysical module: Aerosol Two-dimensional bin module for foRmation and Aging Simulation (ATRAS)

    NASA Astrophysics Data System (ADS)

    Matsui, H.; Koike, M.; Kondo, Y.; Fast, J. D.; Takigawa, M.

    2014-09-01

    Number concentrations, size distributions, and mixing states of aerosols are essential parameters for accurate estimations of aerosol direct and indirect effects. In this study, we develop an aerosol module, designated the Aerosol Two-dimensional bin module for foRmation and Aging Simulation (ATRAS), that can explicitly represent these parameters by considering new particle formation (NPF), black carbon (BC) aging, and secondary organic aerosol (SOA) processes. A two-dimensional bin representation is used for particles with dry diameters from 40 nm to 10 μm to resolve both aerosol sizes (12 bins) and BC mixing states (10 bins) for a total of 120 bins. The particles with diameters between 1 and 40 nm are resolved using additional eight size bins to calculate NPF. The ATRAS module is implemented in the WRF-Chem model and applied to examine the sensitivity of simulated mass, number, size distributions, and optical and radiative parameters of aerosols to NPF, BC aging, and SOA processes over East Asia during the spring of 2009. The BC absorption enhancement by coating materials is about 50% over East Asia during the spring, and the contribution of SOA processes to the absorption enhancement is estimated to be 10-20% over northern East Asia and 20-35% over southern East Asia. A clear north-south contrast is also found between the impacts of NPF and SOA processes on cloud condensation nuclei (CCN) concentrations: NPF increases CCN concentrations at higher supersaturations (smaller particles) over northern East Asia, whereas SOA increases CCN concentrations at lower supersaturations (larger particles) over southern East Asia. The application of ATRAS in East Asia also shows that the impact of each process on each optical and radiative parameter depends strongly on the process and the parameter in question. The module can be used in the future as a benchmark model to evaluate the accuracy of simpler aerosol models and examine interactions between NPF, BC aging, and SOA

  13. Development of an aerosol microphysical module: Aerosol Two-dimensional bin module for foRmation and Aging Simulation (ATRAS)

    NASA Astrophysics Data System (ADS)

    Matsui, H.; Koike, M.; Kondo, Y.; Fast, J. D.; Takigawa, M.

    2014-04-01

    Number concentrations, size distributions, and mixing states of aerosols are essential parameters for accurate estimation of aerosol direct and indirect effects. In this study, we develop an aerosol module, designated Aerosol Two-dimensional bin module for foRmation and Aging Simulation (ATRAS), that can represent these parameters explicitly by considering new particle formation (NPF), black carbon (BC) aging, and secondary organic aerosol (SOA) processes. A two-dimensional bin representation is used for particles with dry diameters from 40 nm to 10 μm to resolve both aerosol size (12 bins) and BC mixing state (10 bins) for a total of 120 bins. The particles with diameters from 1 to 40 nm are resolved using an additional 8 size bins to calculate NPF. The ATRAS module is implemented in the WRF-chem model and applied to examine the sensitivity of simulated mass, number, size distributions, and optical and radiative parameters of aerosols to NPF, BC aging and SOA processes over East Asia during the spring of 2009. BC absorption enhancement by coating materials is about 50% over East Asia during the spring, and the contribution of SOA processes to the absorption enhancement is estimated to be 10-20% over northern East Asia and 20-35% over southern East Asia. A clear north-south contrast is also found between the impacts of NPF and SOA processes on cloud condensation nuclei (CCN) concentrations: NPF increases CCN concentrations at higher supersaturations (smaller particles) over northern East Asia, whereas SOA increases CCN concentrations at lower supersaturations (larger particles) over southern East Asia. Application of ATRAS to East Asia also shows that the impact of each process on each optical and radiative parameter depends strongly on the process and the parameter in question. The module can be used in the future as a benchmark model to evaluate the accuracy of simpler aerosol models and examine interactions between NPF, BC aging, and SOA processes under

  14. Sensitivity of thermal infrared nadir instruments to the chemical and microphysical properties of UTLS secondary sulfate aerosols

    NASA Astrophysics Data System (ADS)

    Sellitto, P.; Legras, B.

    2016-01-01

    Monitoring upper-tropospheric-lower-stratospheric (UTLS) secondary sulfate aerosols and their chemical and microphysical properties from satellite nadir observations is crucial to better understand their formation and evolution processes and then to estimate their impact on UTLS chemistry, and on regional and global radiative balance. Here we present a study aimed at the evaluation of the sensitivity of thermal infrared (TIR) satellite nadir observations to the chemical composition and the size distribution of idealised UTLS sulfate aerosol layers. The extinction properties of sulfuric acid/water droplets, for different sulfuric acid mixing ratios and temperatures, are systematically analysed. The extinction coefficients are derived by means of a Mie code, using refractive indices taken from the GEISA (Gestion et Étude des Informations Spectroscopiques Atmosphériques: Management and Study of Spectroscopic Information) spectroscopic database and log-normal size distributions with different effective radii and number concentrations. IASI (Infrared Atmospheric Sounding Interferometer) pseudo-observations are generated using forward radiative transfer calculations performed with the 4A (Automatized Atmospheric Absorption Atlas) radiative transfer model, to estimate the impact of the extinction of idealised aerosol layers, at typical UTLS conditions, on the brightness temperature spectra observed by this satellite instrument. We found a marked and typical spectral signature of these aerosol layers between 700 and 1200 cm-1, due to the absorption bands of the sulfate and bisulfate ions and the undissociated sulfuric acid, with the main absorption peaks at 1170 and 905 cm-1. The dependence of the aerosol spectral signature to the sulfuric acid mixing ratio, and effective number concentration and radius, as well as the role of interfering parameters like the ozone, sulfur dioxide, carbon dioxide and ash absorption, and temperature and water vapour profile uncertainties

  15. Study on optical and microphysical properties of mixed aerosols from lidar during the EMEP 2012 summer campaign at 45oN 26oE

    NASA Astrophysics Data System (ADS)

    Talianu, Camelia; Nicolae, Doina; Belegante, Livio; Marmureanu, Luminita

    2013-04-01

    Aerosols optical and chemical properties in the upper layers of the atmosphere and near ground are variable, as function of the different mixtures of aerosol components resulting from their origin and transport over polluted areas. Due to a complex dynamics of air masses, the Romanian atmosphere has strong influences from dust and biomass-burning transported from South, West or East Europe. The dominant transport, and consequently the dominant aerosol type, depends on the season. As a result of the transport distance from the source and depending on the chemical and physical characteristics of the particles, tropospheric aerosols detected at Magurele, Romania, show different optical and microphysical properties than at the originating source. The differences are caused by the mixing with local particles, and also by the ageing processes and hygroscopic growth during the transport. This paper presents a statistical analysis of tropospheric aerosol optical properties during the EMEP (European Monitoring and Evaluation Programme) summer campaign (08 June - 17 July 2012), as retrieved from multiwavelength Raman and depolarization lidar data. Three elastic (1064, 532 and 355 nm), two Raman (607 and 387 nm) and one depolarization channel (532 nm parallel / 532 nm cross) are used to independently retrieve the backscatter coefficient, extinction coefficient and linear particle depolarization ratio of aerosols between 0.8 and 10 km altitude. Intensive optical parameters (Angstrom exponent, color ratios and color indexes) and microphysical parameters (effective radius, complex refractive index) from multiwavelength optical data inversion of the layer mean values are obtained. During the campaign, aerosol profiles were measured daily around sunset, following EARLINET standards. An intensive 3-days continuous measurements exercise was also performed. Layers were generally present above 2 km and bellow 6 km altitude, but descent of air masses from the free troposphere to the

  16. Microphysical, Macrophysical and Radiative Signatures of Volcanic Aerosols in Trade Wind Cumulus Observed by the A-Train

    NASA Technical Reports Server (NTRS)

    Yuan, T.; Remer, L. A.; Yu, H.

    2011-01-01

    Increased aerosol concentrations can raise planetary albedo not only by reflecting sunlight and increasing cloud albedo, but also by changing cloud amount. However, detecting aerosol effect on cloud amount has been elusive to both observations and modeling due to potential buffering mechanisms and convolution of meteorology. Here through a natural experiment provided by long-tem1 degassing of a low-lying volcano and use of A-Train satellite observations, we show modifications of trade cumulus cloud fields including decreased droplet size, decreased precipitation efficiency and increased cloud amount are associated with volcanic aerosols. In addition we find significantly higher cloud tops for polluted clouds. We demonstrate that the observed microphysical and macrophysical changes cannot be explained by synoptic meteorology or the orographic effect of the Hawaiian Islands. The "total shortwave aerosol forcin", resulting from direct and indirect forcings including both cloud albedo and cloud amount. is almost an order of magnitude higher than aerosol direct forcing alone. Furthermore, the precipitation reduction associated with enhanced aerosol leads to large changes in the energetics of air-sea exchange and trade wind boundary layer. Our results represent the first observational evidence of large-scale increase of cloud amount due to aerosols in a trade cumulus regime, which can be used to constrain the representation of aerosol-cloud interactions in climate models. The findings also have implications for volcano-climate interactions and climate mitigation research.

  17. Chemical, microphysical and optical properties of the aerosols during foggy and nonfoggy day over a typical location in Indo-Gangetic Plain

    NASA Astrophysics Data System (ADS)

    Kaul, D. S.; Tripathi, S. N.; Gupta, T.

    2012-04-01

    An extensive experimental measurement was carried out from January 16, 2010 to February 20, 2010 at Kanpur to study the chemical, microphysical and optical properties of the aerosols. A Micro-Pulse Lidar Network (MPLNET), a part of National Aeronautic Space Administration (NASA), was used for identification of fog duration. PM1 samples and fogwater were collected to examine the organic and inorganic species of aerosol and fogwater. Organic Carbon (OC), Elemental Carbon (EC) and water soluble organic carbon analysis were carried out by an EC-OC analyzer and a TOC analyzer, respectively. Trace gases and solar flux measurement were carried out by gas analyzers and a pyranometer (a part of NASA Aeronet), respectively, to identify the photo-chemical activity. Meteorological data were measured by atmospheric weather station. The microphysical properties such as aerosol size distribution were measured using a scanning mobility particle sizer (SMPS). Optical properties were measured by a photo-acoustic soot spectrometer (PASS). Organic and inorganic species are processed by fog droplets such as production of secondary organic aerosol through aqueous mechanism (Kaul et al., 2011) and scavenging of various water soluble species. The concentrations of almost all the ionic species and organic carbon were higher in aerosols during foggy day. Presence of numerous ionic species and organic carbon in the fogwater indicates their wet scavenging and removal from the atmosphere by the fog droplets. Most of the aerosol is composed of inorganic component, ~80% during foggy day and ~85.5 % during clear day. Biomass burning contribution to PM1 mass concentration was considerably higher during clear days and lower during foggy days; lower concentration during foggy day could be due to wet scavenging of biomass generated aerosols. The study average higher number concentration of aerosol during foggy day during late evening and overnight was due to lower boundary layer height and subsequent

  18. AERONET-based microphysical and optical properties of smoke-dominated aerosol near source regions and transported over oceans, and implications for satellite retrievals of aerosol optical depth

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    Smoke aerosols from biomass burning are an important component of the global aerosol cycle. Analysis of Aerosol Robotic Network (AERONET) retrievals of size distribution and refractive index reveals variety between biomass burning aerosols in different global source regions, in terms of aerosol particle size and single scatter albedo (SSA). Case studies of smoke transported to coastal/island AERONET sites also mostly lie within the range of variability at near-source sites. Two broad ''families'' of aerosol properties are found, corresponding to sites dominated by boreal forest burning (larger, broader fine mode, with midvisible SSA ∼0.95), and those influenced by grass, shrub, or crop burning with additional forest contributions (smaller, narrower particles with SSA ∼0.88-0.9 in the midvisible). The strongest absorption is seen in southern African savannah at Mongu (Zambia), with average SSA ∼0.85 in the midvisible. These can serve as candidate sets of aerosol microphysical/optical properties for use in satellite aerosol optical depth (AOD) retrieval algorithms. The models presently adopted by these algorithms over ocean are often insufficiently absorbing to represent these biomass burning aerosols. A corollary of this is an underestimate of AOD in smoke outflow regions, which has important consequences for applications of these satellite datasets.

  19. Influence of the micro-physical properties of the aerosol on the atmospheric correction of OLI data acquired over desert area

    NASA Astrophysics Data System (ADS)

    Manzo, Ciro; Bassani, Cristiana

    2016-04-01

    This paper focuses on the evaluation of surface reflectance obtained by different atmospheric correction algorithms of the Landsat 8 OLI data considering or not the micro-physical properties of the aerosol when images are acquired in desert area located in South-West of Nile delta. The atmospheric correction of remote sensing data was shown to be sensitive to the aerosol micro-physical properties, as reported in Bassani et al., 2012. In particular, the role of the aerosol micro-physical properties on the accuracy of the atmospheric correction of remote sensing data was investigated [Bassani et al., 2015; Tirelli et al., 2015]. In this work, the OLI surface reflectance was retrieved by the developed OLI@CRI (OLI ATmospherically Corrected Reflectance Imagery) physically-based atmospheric correction which considers the aerosol micro-physical properties available from the two AERONET stations [Holben et al., 1998] close to the study area (El_Farafra and Cairo_EMA_2). The OLI@CRI algorithm is based on 6SV radiative transfer model, last generation of the Second Simulation of a Satellite Signal in the Solar Spectrum (6S) radiative transfer code [Kotchenova et al., 2007; Vermote et al., 1997], specifically developed for Landsat 8 OLI data. The OLI reflectance obtained by the OLI@CRI was compared with reflectance obtained by other atmospheric correction algorithms which do not consider micro-physical properties of aerosol (DOS) or take on aerosol standard models (FLAASH, implemented in ENVI software). The accuracy of the surface reflectance retrieved by different algorithms were calculated by comparing the spatially resampled OLI images with the MODIS surface reflectance products. Finally, specific image processing was applied to the OLI reflectance images in order to compare remote sensing products obtained for same scene. The results highlight the influence of the physical characterization of aerosol on the OLI data improving the retrieved atmospherically corrected

  20. Sensitivity of clear-sky direct radiative effect of the aerosol to micro-physical properties by using 6SV radiative transfer model: preliminary results

    NASA Astrophysics Data System (ADS)

    Bassani, Cristiana; Tirelli, Cecilia; Manzo, Ciro; Pietrodangelo, Adriana; Curci, Gabriele

    2015-04-01

    The aerosol micro-physical properties are crucial to analyze their radiative impact on the Earth's radiation budget [IPCC, 2007]. The 6SV model, last generation of the Second Simulation of a Satellite Signal in the Solar Spectrum (6S) radiative transfer code [Kotchenova et al., 2007; Vermote et al., 1997] has been used to perform physically-based atmospheric correction of hyperspectral airborne and aircraft remote sensing data [Vermote et al., 2009; Bassani et al. 2010; Tirelli et al., 2014]. The atmospheric correction of hyperspectral data has been shown to be sensitive to the aerosol micro-physical properties, as reported in Bassani et al., 2012. The role of the aerosol micro-physical properties on the accuracy of the atmospheric correction of hyperspectral data acquired over water and land targets is investigated within the framework of CLAM-PHYM (Coasts and Lake Assessment and Monitoring by PRISMA HYperspectral Mission) and PRIMES (Synergistic use of PRISMA products with high resolution meteo-chemical simulations and their validation on ground and from satellite) projects, both funded by Italian Space Agency (ASI). In this work, the results of the radiative field of the Earth/Atmosphere coupled system simulated by using 6SV during the atmospheric correction of hyperspectral data are presented. The analysis of the clear-sky direct radiative effect is performed considering the aerosol micro-physical properties used to define the aerosol model during the atmospheric correction process. In particular, the AERONET [Holben et al., 1998] and FLEXAOD [Curci et al., 2014] micro-physical properties are used for each image to evaluate the contribution of the size distribution and refractive index of the aerosol type on the surface reflectance and on the direct radiative forcing. The results highlight the potential of the hyperspectral remote sensing data for atmospheric studies as well as for environmental studies. Currently, the future hyperspectral missions, such as the

  1. Comparison of observed and simulated spatial patterns of ice microphysical processes in tropical oceanic mesoscale convective systems: Ice Microphysics in Midlevel Inflow

    SciTech Connect

    Barnes, Hannah C.; Houze, Robert A.

    2016-07-25

    To equitably compare the spatial pattern of ice microphysical processes produced by three microphysical parameterizations with each other, observations, and theory, simulations of tropical oceanic mesoscale convective systems (MCSs) in the Weather Research and Forecasting (WRF) model were forced to develop the same mesoscale circulations as observations by assimilating radial velocity data from a Doppler radar. The same general layering of microphysical processes was found in observations and simulations with deposition anywhere above the 0°C level, aggregation at and above the 0°C level, melting at and below the 0°C level, and riming near the 0°C level. Thus, this study is consistent with the layered ice microphysical pattern portrayed in previous conceptual models and indicated by dual-polarization radar data. Spatial variability of riming in the simulations suggests that riming in the midlevel inflow is related to convective-scale vertical velocity perturbations. Finally, this study sheds light on limitations of current generally available bulk microphysical parameterizations. In each parameterization, the layers in which aggregation and riming took place were generally too thick and the frequency of riming was generally too high compared to the observations and theory. Additionally, none of the parameterizations produced similar details in every microphysical spatial pattern. Discrepancies in the patterns of microphysical processes between parameterizations likely factor into creating substantial differences in model reflectivity patterns. It is concluded that improved parameterizations of ice-phase microphysics will be essential to obtain reliable, consistent model simulations of tropical oceanic MCSs.

  2. Overview of the Cumulus Humilis Aerosol Processing Study

    SciTech Connect

    Berg, Larry K.; Berkowitz, Carl M.; Ogren, John A.; Hostetler, Chris A.; Ferrare, Richard; Dubey, Manvendra K.; Andrews, Elizabeth; Coulter, Richard L.; Hair, John; Hubbe, John M.; Lee, Yin-Nan; Mazzoleni, Claudio; Olfert, Jason N.; Springston, Stephen R.

    2009-11-30

    The primary goal of the Cumulus Humilis Aerosol Processing Study (CHAPS) was to characterize and contrast freshly emitted aerosols below, above, and within fields of cumuli, and to study changes to the cloud microphysical structure within these same cloud fields. The CHAPS is one of very few studies that have had an Aerosol Mass Spectrometer (AMS) sampling downstream of a counter-flow virtual impactor (CVI) inlet on an aircraft, allowing the examination of the chemical composition of the nucleated aerosols within the cumuli. The results from the CHAPS will provide insights into changes in the aerosol chemical and optical properties as aerosols move through shallow cumuli downwind of a moderately sized city. Three instrument platforms were employed during the CHAPS, including the U.S. Department of Energy Gulfstream-1 aircraft, which was equipped for in situ sampling of aerosol optical and chemical properties; the NASA-Langley King Air B200, which carried the downward looking NASA Langley High Spectral Resolution Lidar (HSRL) to measure profiles of aerosol backscatter, extinction, and depolarization between the King Air and the surface; and a surface site equipped for continuous in situ measurements of aerosol properties, profiles of aerosol backscatter, and meteorological conditions including total sky cover and thermodynamic profiles of the atmosphere. In spite of record precipitation over central Oklahoma, a total of eight research flights were made by the G-1, and eighteen by the B200, including special satellite verification flights timed to coincide with NASA satellite A-Train overpasses.

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

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Li, X.; Khain, A.; Simpson, S.

    2005-01-01

    Cloud microphysics are inevitable affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds, Therefore, size distributions parameterized as spectral bin microphysics are needed to explicitly study the effect of atmospheric aerosol concentration on cloud development, rainfall production, and rainfall rates for convective clouds. Recently, a detailed spectral-bin microphysical scheme was implemented into the the Goddard Cumulus Ensemble (GCE) model. The formulation for the explicit spectral-bim microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles [i.e., pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), graupel and frozen drops/hail]. Each type is described by a special size distribution function containing many categories (i.e., 33 bins). Atmospheric aerosols are also described using number density size-distribution functions.

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

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Li, X.; Khain, A.; Simpson, S.; Johnson, D.; Remer, L.

    2004-01-01

    Cloud microphysics is inevitably affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds. Therefore, size distributions parameterized as spectral bin microphysics are needed to explicitly study the effects of atmospheric aerosol concentration on cloud development, rainfall production, and rainfall rates for convective clouds. Recently, two detailed spectral-bin microphysical schemes were implemented into the Goddard Cumulus Ensembel (GCE) model. The formulation for the explicit spectral-bin microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles [i.e. pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), graupel and frozen drops/hail]. Each type is described by a special size distribution function containing many categories (i.e. 33 bins). Atmospheric aerosols are also described using number density size distribution functions. A spectral-bin microphysical model is very expensive from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep tropical clouds in the west Pacific warm pool region and in the mid-latitude continent with different concentrations of CCN: a low "c1ean"concentration and a high "dirty" concentration. In addition, differences and similarities between bulk microphysics and spectral-bin microphysical schemes will be examined and discussed.

  5. The Impact of Aerosols on Cloud and Precipitation Processes: Cloud-resolving Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Li, X.; Khain, A.; Simpson, S.; Johnson, D.; Remer, L.

    2004-01-01

    Cloud microphysics is inevitably affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds. Therefore, size distributions parameterized as spectral bin microphysics are needed to explicitly study the effects of atmospheric aerosol concentration on cloud development, r d a U production, and rainfall rates for convective clouds. Recently, two detailed spectral-bin microphysical schemes were implemented into the Goddard Cumulus Ensembe1 (GCE) model. The formulation for the explicit spectral-bin microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles [i.e. pristine ice crystals (columnar and platelike), snow (dendrites and aggregates), graupel and frozen drops/hail]. Each type is described by a special size distribution function containing many categories (i.e. 33 bins). Atmospheric aerosols are also described using number density size-distribution functions. A spectral-bin microphysical model is very expensive from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep tropical clouds in the west Pacific warm pool region and in the mid-latitude continent with different concentrations of CCN: a low "c1ean"concentration and a high "dirty" concentration. In addition, differences and similarities between bulk microphysics and spectral-bin microphysical schemes will be examined and discussed.

  6. 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

  7. 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

  8. Determining Best Estimates and Uncertainties in Cloud Microphysical Parameters from ARM Field Data: Implications for Models, Retrieval Schemes and Aerosol-Cloud-Radiation Interactions

    SciTech Connect

    McFarquhar, Greg

    2015-12-28

    We proposed to analyze in-situ cloud data collected during ARM/ASR field campaigns to create databases of cloud microphysical properties and their uncertainties as needed for the development of improved cloud parameterizations for models and remote sensing retrievals, and for evaluation of model simulations and retrievals. In particular, we proposed to analyze data collected over the Southern Great Plains (SGP) during the Mid-latitude Continental Convective Clouds Experiment (MC3E), the Storm Peak Laboratory Cloud Property Validation Experiment (STORMVEX), the Small Particles in Cirrus (SPARTICUS) Experiment and the Routine AAF Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) field campaign, over the North Slope of Alaska during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) and the Mixed-Phase Arctic Cloud Experiment (M-PACE), and over the Tropical Western Pacific (TWP) during The Tropical Warm Pool International Cloud Experiment (TWP-ICE), to meet the following 3 objectives; derive statistical databases of single ice particle properties (aspect ratio AR, dominant habit, mass, projected area) and distributions of ice crystals (size distributions SDs, mass-dimension m-D, area-dimension A-D relations, mass-weighted fall speeds, single-scattering properties, total concentrations N, ice mass contents IWC), complete with uncertainty estimates; assess processes by which aerosols modulate cloud properties in arctic stratus and mid-latitude cumuli, and quantify aerosol’s influence in context of varying meteorological and surface conditions; and determine how ice cloud microphysical, single-scattering and fall-out properties and contributions of small ice crystals to such properties vary according to location, environment, surface, meteorological and aerosol conditions, and develop parameterizations of such effects.In this report we describe the accomplishments that we made on all 3 research objectives.

  9. Retrieval of Aerosol Microphysical Properties from AERONET Photo-Polarimetric Measurements. 2: A New Research Algorithm and Case Demonstration

    NASA Technical Reports Server (NTRS)

    Xu, Xiaoguang; Wang, Jun; Zeng, Jing; Spurr, Robert; Liu, Xiong; Dubovik, Oleg; Li, Li; Li, Zhengqiang; Mishchenko, Michael I.; Siniuk, Aliaksandr; Holben, Brent N.

    2015-01-01

    A new research algorithm is presented here as the second part of a two-part study to retrieve aerosol microphysical properties from the multispectral and multiangular photopolarimetric measurements taken by Aerosol Robotic Network's (AERONET's) new-generation Sun photometer. The algorithm uses an advanced UNified and Linearized Vector Radiative Transfer Model and incorporates a statistical optimization approach.While the new algorithmhas heritage from AERONET operational inversion algorithm in constraining a priori and retrieval smoothness, it has two new features. First, the new algorithmretrieves the effective radius, effective variance, and total volume of aerosols associated with a continuous bimodal particle size distribution (PSD) function, while the AERONET operational algorithm retrieves aerosol volume over 22 size bins. Second, our algorithm retrieves complex refractive indices for both fine and coarsemodes,while the AERONET operational algorithm assumes a size-independent aerosol refractive index. Mode-resolved refractive indices can improve the estimate of the single-scattering albedo (SSA) for each aerosol mode and thus facilitate the validation of satellite products and chemistry transport models. We applied the algorithm to a suite of real cases over Beijing_RADI site and found that our retrievals are overall consistent with AERONET operational inversions but can offer mode-resolved refractive index and SSA with acceptable accuracy for the aerosol composed by spherical particles. Along with the retrieval using both radiance and polarization, we also performed radiance-only retrieval to demonstrate the improvements by adding polarization in the inversion. Contrast analysis indicates that with polarization, retrieval error can be reduced by over 50% in PSD parameters, 10-30% in the refractive index, and 10-40% in SSA, which is consistent with theoretical analysis presented in the companion paper of this two-part study.

  10. Measurements of regional-scale aerosol impacts on cloud microphysics over the East China Sea: Possible influences of warm sea surface temperature over the Kuroshio ocean current

    NASA Astrophysics Data System (ADS)

    Koike, M.; Takegawa, N.; Moteki, N.; Kondo, Y.; Nakamura, H.; Kita, K.; Matsui, H.; Oshima, N.; Kajino, M.; Nakajima, T. Y.

    2012-09-01

    Cloud microphysical properties and aerosol concentrations were measured aboard an aircraft over the East China Sea and Yellow Sea in April 2009 during the Aerosol Radiative Forcing in East Asia (A-FORCE) experiment. We sampled stratocumulus and shallow cumulus clouds over the ocean in 9 cases during 7 flights 500-900 km off the east coast of Mainland China. In this study we report aerosol impacts on cloud microphysical properties by focusing on regional characteristics of two key parameters, namely updraft velocity and aerosol size distribution. First, we show that the cloud droplet number concentration (highest 5%, Nc_max) correlates well with the accumulation-mode aerosol number concentration (Na) below the clouds. We then show that Nc_maxcorrelates partly with near-surface stratification evaluated as the difference between the sea surface temperature (SST) and 950-hPa temperature (SST - T950). Cold air advection from China to the East China Sea was found to bring not only a large number of aerosols but also a dry and cold air mass that destabilized the atmospheric boundary layer, especially over the warm Kuroshio ocean current. Over this high-SST region, greater updraft velocities and hence greater Nc_maxlikely resulted. We hypothesize that the low-level static stability determined by SST and regional-scale airflow modulates both the cloud microphysics (aerosol impact on clouds) and macro-structure of clouds (cloud base and top altitudes, hence cloud liquid water path). Second, we show that not only higher aerosol loading in terms of total aerosol number concentration (NCN, D > 10 nm) but also larger aerosol mode diameters likely contributed to high Ncduring A-FORCE. The mean Nc of 650 ± 240 cm-3was more than a factor of 2 larger than the global average for clouds influenced by continental sources. A crude estimate of the aerosol-induced cloud albedo radiative forcing is also given.

  11. Factors influencing the microphysics and radiative properties of liquid-dominated Arctic clouds: insight from observations of aerosol and clouds during ISDAC

    SciTech Connect

    Earle, Michael; Liu, Peter S.; Strapp, J. Walter; Zelenyuk, Alla; Imre, D.; McFarquhar, Greg; Shantz, Nicole C.; Leaitch, W. R.

    2011-11-04

    Aircraft measurements during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in April 2008 are used to investigate aerosol indirect effects in Arctic clouds. Two aerosol-cloud regimes are considered in this analysis: single-layer stratocumulus cloud with below-cloud aerosol concentrations (N{sub a}) below 300 cm{sup -3} on April 8 and April 26-27 (clean cases); and inhomogeneous layered cloud with N{sub a} > 500 cm{sup -3} below cloud base on April 19-20, concurrent with a biomass burning episode (polluted cases). Vertical profiles through cloud in each regime are used to determine average cloud microphysical and optical properties. Positive correlations between the cloud droplet effective radius (Re) and cloud optical depth ({tau}) are observed for both clean and polluted cases, which are characteristic of optically-thin, non-precipitating clouds. Average Re values for each case are {approx} 6.2 {mu}m, despite significantly higher droplet number concentrations (Nd) in the polluted cases. The apparent independence of Re and Nd simplifies the description of indirect effects, such that {tau} and the cloud albedo (A) can be described by relatively simple functions of the cloud liquid water path. Adiabatic cloud parcel model simulations show that the marked differences in Na between the regimes account largely for differences in droplet activation, but that the properties of precursor aerosol also play a role, particularly for polluted cases where competition for vapour amongst the more numerous particles limits activation to larger and/or more hygroscopic particles. The similarity of Re for clean and polluted cases is attributed to compensating droplet growth processes for different initial droplet size distributions.

  12. Interactions between aerosol absorption, thermodynamics, dynamics, and microphysics and their impacts on a multiple-cloud system

    NASA Astrophysics Data System (ADS)

    Lee, Seoung Soo; Li, Zhanqing; Mok, Jungbin; Ahn, Myoung-Hwan; Kim, Byung-Gon; Choi, Yong-Sang; Jung, Chang-Hoon; Yoo, Hye Lim

    2017-02-01

    This study investigates how the increasing concentration of black carbon aerosols, which act as radiation absorbers as well as agents for the cloud-particle nucleation, affects stability, dynamics and microphysics in a multiple-cloud system using simulations. Simulations show that despite increases in stability due to increasing concentrations of black carbon aerosols, there are increases in the averaged updraft mass fluxes (over the whole simulation domain and period). This is because aerosol-enhanced evaporative cooling intensifies convergence near the surface. This increase in the intensity of convergence induces an increase in the frequency of updrafts with the low range of speeds, leading to the increase in the averaged updraft mass fluxes. The increase in the frequency of updrafts induces that in the number of condensation entities and this leads to more condensation and cloud liquid that acts to be a source of the accretion of cloud liquid by precipitation. Hence, eventually, there is more accretion that offsets suppressed autoconversion, which results in negligible changes in cumulative precipitation as aerosol concentrations increase. The increase in the frequency of updrafts with the low range of speeds alters the cloud-system organization (represented by cloud-depth spatiotemporal distributions and cloud-cell population) by supporting more low-depth clouds. The altered organization in turn alters precipitation spatiotemporal distributions by generating more weak precipitation events. Aerosol-induced reduction in solar radiation that reaches the surface induces more occurrences of small-value surface heat fluxes, which in turn supports the more low-depth clouds and weak precipitation together with the greater occurrence of low-speed updrafts.

  13. Effects of long-range aerosol transport on the microphysical properties of low-level liquid clouds in the Arctic

    NASA Astrophysics Data System (ADS)

    Coopman, Quentin; Garrett, Timothy J.; Riedi, Jérôme; Eckhardt, Sabine; Stohl, Andreas

    2016-04-01

    The properties of low-level liquid clouds in the Arctic can be altered by long-range pollution transport to the region. Satellite, tracer transport model, and meteorological data sets are used here to determine a net aerosol-cloud interaction (ACInet) parameter that expresses the ratio of relative changes in cloud microphysical properties to relative variations in pollution concentrations while accounting for dry or wet scavenging of aerosols en route to the Arctic. For a period between 2008 and 2010, ACInet is calculated as a function of the cloud liquid water path, temperature, altitude, specific humidity, and lower tropospheric stability. For all data, ACInet averages 0.12 ± 0.02 for cloud-droplet effective radius and 0.16 ± 0.02 for cloud optical depth. It increases with specific humidity and lower tropospheric stability and is highest when pollution concentrations are low. Carefully controlling for meteorological conditions we find that the liquid water path of arctic clouds does not respond strongly to aerosols within pollution plumes. Or, not stratifying the data according to meteorological state can lead to artificially exaggerated calculations of the magnitude of the impacts of pollution on arctic clouds.

  14. Assessment of biomass burning smoke influence on environmental conditions for multiyear tornado outbreaks by combining aerosol-aware microphysics and fire emission constraints

    NASA Astrophysics Data System (ADS)

    Saide, Pablo E.; Thompson, Gregory; Eidhammer, Trude; Silva, Arlindo M.; Pierce, R. Bradley; Carmichael, Gregory R.

    2016-09-01

    We use the Weather Research and Forecasting (WRF) system to study the impacts of biomass burning smoke from Central America on several tornado outbreaks occurring in the U.S. during spring. The model is configured with an aerosol-aware microphysics parameterization capable of resolving aerosol-cloud-radiation interactions in a cost-efficient way for numerical weather prediction (NWP) applications. Primary aerosol emissions are included, and smoke emissions are constrained using an inverse modeling technique and satellite-based aerosol optical depth observations. Simulations turning on and off fire emissions reveal smoke presence in all tornado outbreaks being studied and show an increase in aerosol number concentrations due to smoke. However, the likelihood of occurrence and intensification of tornadoes is higher due to smoke only in cases where cloud droplet number concentration in low-level clouds increases considerably in a way that modifies the environmental conditions where the tornadoes are formed (shallower cloud bases and higher low-level wind shear). Smoke absorption and vertical extent also play a role, with smoke absorption at cloud-level tending to burn-off clouds and smoke absorption above clouds resulting in an increased capping inversion. Comparing these and WRF-Chem simulations configured with a more complex representation of aerosol size and composition and different optical properties, microphysics, and activation schemes, we find similarities in terms of the simulated aerosol optical depths and aerosol impacts on near-storm environments. This provides reliability on the aerosol-aware microphysics scheme as a less computationally expensive alternative to WRF-Chem for its use in applications such as NWP and cloud-resolving simulations.

  15. Impacts of aerosol particles on the microphysical and radiative properties of stratocumulus clouds over the southeast Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Twohy, C. H.; Anderson, J. R.; Toohey, D. W.; Andrejczuk, M.; Adams, A.; Lytle, M.; George, R. C.; Wood, R.; Saide, P.; Spak, S.; Zuidema, P.; Leon, D.

    2013-03-01

    there. Thus, larger scale forcings that impact cloud macrophysical properties, as well as enhanced aerosol particles, are important in determining cloud droplet size and cloud albedo. Differences in the size distribution of droplet residual particles and ambient aerosol particles were observed. By progressively excluding small droplets from the CVI sample, we were able to show that the larger drops, some of which may initiate drizzle, contain the largest aerosol particles. Geometric mean diameters of droplet residual particles were larger than those of the below-cloud and above cloud distributions. However, a wide range of particle sizes can act as droplet nuclei in these stratocumulus clouds. A detailed LES microphysical model was used to show that this can occur without invoking differences in chemical composition of cloud-nucleating particles.

  16. Studyng the Influence of Aerosols in the Evolution of Cloud Microphysics Procesess Associated with Tropical Cyclone Earl Using Airborne Measurements from the NASA Grip Field Campaing 2010

    NASA Astrophysics Data System (ADS)

    Luna-Cruz, Y.; Heymsfield, A.; Jenkins, G. S.; Bansemer, A.

    2011-12-01

    Cloud microphysics processes are strongly related to tropical cyclones evolution. Although there have been three decades of research dedicated to understand the role of cloud microphysics in tropical cyclogenesis, there are still questions unanswered. With the intention of fulfill the gaps and to better understand the processes involves in tropical storms formation the NASA Genesis and Rapid Intensification Processes (GRIP) field campaign was conducted during the months of August and September of 2010. In-situ microphysical measurements, including particle size distributions, shapes, liquid/ice water content and supercooled liquid water were obtained from the DC-8 aircraft. A total of 139 hrs of flying science modules were performed including sampling of four named storms (Earl, Gaston, Karl and Matthew). One tropical cyclone, Earl, was one of the major hurricanes of the season reaching a category 4 in the Saffir-Simpson scale. Earl emerged from the West Africa on August 22 as an easterly wave, moved westward and became a tropical storm on August 25 before undergoing rapid intensification. This project seeks to explore the lifecycle of hurricane Earl including the genesis and rapid intensification from a microphysics perspective; to develop a better understanding of the relationship between dust from the Saharan Air Layer and cloud microphysics evolution and to develop a better understanding of how cloud microphysics processes interacts and serve as precursor for thermodynamics processes. An overview of the microphysics measurements as well as preliminary results will be presented.

  17. Modulations of aerosol impacts on cloud microphysics induced by the warm Kuroshio Current under the East Asian winter monsoon

    NASA Astrophysics Data System (ADS)

    Koike, M.; Asano, N.; Nakamura, H.; Sakai, S.; Nagao, T. M.; Nakajima, T. Y.

    2016-10-01

    In our previous aircraft observations, the possible influence of high sea surface temperature (SST) along the Kuroshio Current on aerosol-cloud interactions over the western North Pacific was revealed. The cloud droplet number concentration (Nc) was found to increase with decreasing near-surface static stability (NSS), which was evaluated locally as the difference between the SST and surface air temperature (SAT). To explore the spatial and temporal extent to which this warm SST influence can be operative, the present study analyzed Nc values estimated from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite measurements. The comparison of the local Nc values between the high and low SST - SAT days revealed a marked increase in Nc (up to a factor of 1.8) along the Kuroshio Current in the southern East China Sea, where particularly high SST - SAT values (up to 8 K) were observed in winter under monsoonal cold air outflows from the Asian Continent. This cold airflow destabilizes the atmospheric boundary layer, which leads to enhanced updraft velocities within the well-developed mixed layer and thus greater Nc. The monsoonal northwesterlies also bring a large amount of anthropogenic aerosols from the Asian continent that increase Nc in the first place. These results suggest that the same modulations of cloud microphysics can occur over other warm western boundary currents, including the Gulf Stream, under polluted cool continental airflows. Possibilities of influencing the cloud liquid water path are also discussed.

  18. Impacts of aerosol particles on the microphysical and radiative properties of stratocumulus clouds over the Southeast Pacific ocean

    NASA Astrophysics Data System (ADS)

    Twohy, C. H.; Anderson, J. R.; Toohey, D. W.; Andrejczuk, M.; Adams, A.; Lytle, M.; George, R. C.; Wood, R.; Saide, P.; Spak, S.; Zuidema, P.; Leon, D.

    2012-08-01

    distribution of droplet residual particles and ambient aerosol particles were observed. By progressively excluding small droplets from the CVI sample, we were able to show that the larger drops, which initiate drizzle, contain the largest aerosol particles. Geometric mean diameters of droplet residual particles were larger than those of the below-cloud and above cloud distributions. However, a wide range of particle sizes can act as droplet nuclei in these stratocumulus clouds. A detailed LES microphysical model was used to show that this can occur without invoking differences in chemical composition of cloud-nucleating particles.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Giannakaki, E.; van Zyl, P. G.; Müller, D.; Balis, D.; Komppula, M.

    2015-12-01

    Optical and microphysical properties of different aerosol types over South Africa measured with a multi-wavelength polarization Raman lidar are presented. This study could assist in bridging existing gaps relating to aerosol properties over South Africa, since limited long-term data of this type is available for this region. The observations were performed under the framework of the EUCAARI campaign in Elandsfontein. The multi-wavelength PollyXT Raman lidar system was used to determine vertical profiles of the aerosol optical properties, i.e. extinction and backscatter coefficients, Ångström exponents, lidar ratio and depolarization ratio. The mean microphysical aerosol proper ties, i.e. effective radius and single scattering, albedo were retrieved with an advanced inversion algorithm. Clear differences were observed for the intensive optical properties of atmospheric layers of biomass burning and urban/industrial aerosols. Our results reveal a wide range of optical and microphysical parameters for biomass burning aerosols. This indicates probable mixing of biomass burning aerosols with desert dust particles, as well as the possible continuous influence of urban/industrial aerosol load in the region. The lidar ratio at 355 nm, the linear particle depolarization ratio at 355 nm and the extinction-related Ångström exponent from 355 to 532 nm were 52 ± 7 sr; 0.9 ± 0.4 % and 2.3 ± 0.5, respectively for urban/industrial aerosols, while these values were 92 ± 10 sr; 3.2 ± 1.3 %; 2.0 ± 0.4 respectively for biomass burning aerosols layers. Biomass burning particles are larger and slightly less absorbing compared to urban/industrial aerosols. The particle effective radius were found to be 0.10 ± 0.03, 0.17 ± 0.04 and 0.13 ± 0.03 μm for urban/industrial, biomass burning, and mixed biomass burning and desert dust aerosols, respectively, while the single scattering albedo at 532 nm were 0.87 ± 0.06, 0.90 ± 0.06, and 0.88 ± 0.07 (at 532 nm), respectively for

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

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Li, X.; Khain, A.; Simpson, S.

    2004-01-01

    Cloud microphysics are inevitably affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds. Therefore, size distributions parameterized as spectral bin microphysics are needed to explicitly study the effects of atmospheric aerosol concentration on cloud development, rainfall production, and rainfall rates for convective clouds. Recently, two detailed spectral-bin microphysical schemes were implemented into the Goddard Cumulus Ensemble (GCE) model. The formulation for the explicit spectral-bin microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles (i.e., pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), graupel and frozen drops/hail). Each type is described by a special size distribution function containing many categories (i.e. 33 bins). Atmospheric aerosols are also described using number density size-distribution functions. A spectral-bin microphysical model is very expensive from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep cloud systems in the west Pacific warm pool region, in the sub-tropics (Florida) and in the mid-latitude using identical thermodynamic conditions but with different concentrations of CCN: a low 'clean' concentration and a high 'dirty' concentration.

  2. 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

    parameterisation in ECHAM5-HAM utilising the aerosol microphysical models SALSA and M7. We will present a comparison of the global particle size distributions predicted with and without cloud activation parameterisation to evaluate the effect of cloud processing on the aerosol size distribution.

  3. Utilization of AERONET polarimetric measurements for improving retrieval of aerosol microphysics: GSFC, Beijing and Dakar data analysis

    NASA Astrophysics Data System (ADS)

    Fedarenka, Anton; Dubovik, Oleg; Goloub, Philippe; Li, Zhengqiang; Lapyonok, Tatyana; Litvinov, Pavel; Barel, Luc; Gonzalez, Louis; Podvin, Thierry; Crozel, Didier

    2016-08-01

    The study presents the efforts on including the polarimetric data to the routine inversion of the radiometric ground-based measurements for characterization of the atmospheric aerosols and analysis of the obtained advantages in retrieval results. First, to operationally process the large amount of polarimetric data the data preparation tool was developed. The AERONET inversion code adapted for inversion of both intensity and polarization measurements was used for processing. Second, in order to estimate the effect from utilization of polarimetric information on aerosol retrieval results, both synthetic data and the real measurements were processed using developed routine and analyzed. The sensitivity study has been carried out using simulated data based on three main aerosol models: desert dust, urban industrial and urban clean aerosols. The test investigated the effects of utilization of polarization data in the presence of random noise, bias in measurements of optical thickness and angular pointing shift. The results demonstrate the advantage of polarization data utilization in the cases of aerosols with pronounced concentration of fine particles. Further, the extended set of AERONET observations was processed. The data for three sites have been used: GSFC, USA (clean urban aerosol dominated by fine particles), Beijing, China (polluted industrial aerosol characterized by pronounced mixture of both fine and coarse modes) and Dakar, Senegal (desert dust dominated by coarse particles). The results revealed considerable advantage of polarimetric data applying for characterizing fine mode dominated aerosols including industrial pollution (Beijing). The use of polarization corrects particle size distribution by decreasing overestimated fine mode and increasing the coarse mode. It also increases underestimated real part of the refractive index and improves the retrieval of the fraction of spherical particles due to high sensitivity of polarization to particle shape

  4. Comparison of observed and simulated spatial patterns of ice microphysical processes in tropical oceanic mesoscale convective systems

    NASA Astrophysics Data System (ADS)

    Barnes, Hannah C.; Houze, Robert A.

    2016-07-01

    To equitably compare the spatial pattern of ice microphysical processes produced by three microphysical parameterizations with each other, observations, and theory, simulations of tropical oceanic mesoscale convective systems (MCSs) in the Weather Research and Forecasting (WRF) model were forced to develop the same mesoscale circulations as observations by assimilating radial velocity data from a Doppler radar. The same general layering of microphysical processes was found in observations and simulations with deposition anywhere above the 0°C level, aggregation at and above the 0°C level, melting at and below the 0°C level, and riming near the 0°C level. Thus, this study is consistent with the layered ice microphysical pattern portrayed in previous conceptual models and indicated by dual-polarization radar data. Spatial variability of riming in the simulations suggests that riming in the midlevel inflow is related to convective-scale vertical velocity perturbations. Finally, this study sheds light on limitations of current generally available bulk microphysical parameterizations. In each parameterization, the layers in which aggregation and riming took place were generally too thick and the frequency of riming was generally too high compared to the observations and theory. Additionally, none of the parameterizations produced similar details in every microphysical spatial pattern. Discrepancies in the patterns of microphysical processes between parameterizations likely factor into creating substantial differences in model reflectivity patterns. It is concluded that improved parameterizations of ice-phase microphysics will be essential to obtain reliable, consistent model simulations of tropical oceanic MCSs.

  5. The hydrometeor partitioning and microphysical processes over the Pacific Warm Pool in numerical modeling

    NASA Astrophysics Data System (ADS)

    Huang, Yi-Chih; Wang, Pao K.

    2017-01-01

    Numerical modeling is conducted to study the hydrometeor partitioning and microphysical source and sink processes during a quasi-steady state of thunderstorms over the Pacific Warm Pool by utilizing the microphysical model WISCDYMM to simulate selected storm cases. The results show that liquid-phase hydrometeors dominate thunderstorm evolution over the Pacific Warm Pool. The ratio of ice-phase mass to liquid-phase mass is about 41%: 59%, indicating that ice-phase water is not as significant over the Pacific Warm Pool as the liquid water compared to the larger than 50% in the subtropics and 80% in the US High Plains in a previous study. Sensitivity tests support the dominance of liquid-phase hydrometeors over the Pacific Warm Pool. The major rain sources are the key hail sinks: melting of hail and shedding from hail; whereas the crucial rain sinks are evaporation and accretion by hail. The major snow sources are Bergeron-Findeisen process, transfer of cloud ice to snow and accretion of cloud water; whereas the foremost sink of snow is accretion by hail. The essential hail sources are accretions of rain, cloud water, and snow; whereas the critical hail sinks are melting of hail and shedding from hail. The contribution and ranking of sources and sinks of these precipitates are compared with the previous study. Hydrometeors have their own special microphysical processes in the development and depletion over the Pacific Warm Pool. Microphysical budgets depend on atmospheric dynamical and thermodynamical conditions which determine the partitioning of hydrometeors. This knowledge would benefit the microphysics parameterization in cloud models and cumulus parameterization in global circulation models.

  6. 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.

  7. 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

  8. The Microphysical and Chemical properties of aerosol particles from the United Arab Emirates Unified Aerosol Experiment (UAE2) and from the Bodele-BODEX Experiment

    NASA Astrophysics Data System (ADS)

    Martins, J.; Chaudhry, Z.; Todd, M.; Kaufman, Y.; Artaxo, P.

    2005-12-01

    Aerosol filters collected during the UAE2 experiment (August 2004), and during the BODEX experiment (in the Bodele region, February 2005) were analyzed for spectral absorption properties (from 350-2500nm), mass concentration (fine and coarse modes), electron microscopy, and chemical composition. The UAE2 samples show evidence of absorption by dust and urban pollution particles. In the fine mode, the urban pollution particles show spectral dependence inversely proportional to the wavelength, which is compatible with small black carbon aerosols. The coarse mode shows evidences of the internal mixture between dust and pollution, producing the typical strong absorption in UV-Visible wavelengths produced by dust, as well as significant absorption in the NIR (near infrared) coming from the dust-pollution combination. On the other hand, the Bodele samples show at least two types of dust absorption behavior: 1 - very strong absorption efficiency in the UV and visible wavelengths with nearly no absorption in the NIR; 2 - very strong absorption efficiency in the UV-VIS region with significant absorption in the NIR. Additional samples collected in the Amazon region, in Brazil, show evidence of long-range transport of dust from the Sahara. The chemical composition and microphysical properties of the Amazon Samples are compared with those measured in the UAE and Bodele regions. The chemical composition of these samples provides additional insight on previous theories of the fertilization of the Amazon by long-range transport of dust from the Sahara region.

  9. Aerosol and cloud microphysics covariability in the northeast Pacific boundary layer estimated with ship-based and satellite remote sensing observations: NE Pacific Aerosol-Cloud Interactions

    DOE PAGES

    Painemal, David; Chiu, J. -Y. Christine; Minnis, Patrick; ...

    2017-02-27

    We utilized ship measurements collected over the northeast Pacific along transects between the port of Los Angeles (33.7°N, 118.2°W) and Honolulu (21.3°N, 157.8°W) during May to August 2013 in order to investigate the covariability between marine low cloud microphysical and aerosol properties. Ship-based retrievals of cloud optical depth (τ) from a Sun photometer and liquid water path (LWP) from a microwave radiometer were combined to derive cloud droplet number concentration Nd and compute a cloud-aerosol interaction (ACI) metric defined as ACICCN=∂ ln(Nd)/∂ ln(CCN), with CCN denoting the cloud condensation nuclei concentration measured at 0.4% (CCN0.4) and 0.3% (CCN0.3) supersaturation. Analysismore » of CCN0.4, accumulation mode aerosol concentration (Na), and extinction coefficient (σext) indicates that Na and σext can be used as CCN0.4 proxies for estimating ACI. ACICCN derived from 10 min averaged Nd and CCN0.4 and CCN0.3, and CCN0.4 regressions using Na and σext, produce high ACICCN: near 1.0, that is, a fractional change in aerosols is associated with an equivalent fractional change in Nd. ACICCN computed in deep boundary layers was small (ACICCN=0.60), indicating that surface aerosol measurements inadequately represent the aerosol variability below clouds. Satellite cloud retrievals from MODerate-resolution Imaging Spectroradiometer and GOES-15 data were compared against ship-based retrievals and further analyzed to compute a satellite-based ACICCN. We found that the satellite data correlated well with their ship-based counterparts with linear correlation coefficients equal to or greater than 0.78. Combined satellite Nd and ship-based CCN0.4 and Na yielded a maximum ACICCN=0.88–0.92, a value slightly less than the ship-based ACICCN, but still consistent with aircraft-based studies in the eastern Pacific.« less

  10. Link between aerosol optical, microphysical and chemical measurements in an underground railway station in Paris

    NASA Astrophysics Data System (ADS)

    Raut, J.-C.; Chazette, P.; Fortain, A.

    Measurements carried out in Paris Magenta railway station in April-May 2006 underlined a repeatable diurnal cycle of aerosol concentrations and optical properties. The average daytime PM 10 and PM 2.5 concentrations in such a confined space were approximately 5-30 times higher than those measured in Paris streets. Particles are mainly constituted of dust, with high concentrations of iron and other metals, but are also composed of black and organic carbon. Aerosol levels are linked to the rate at which rain and people pass through the station. Concentrations are also influenced by ambient air from the nearby streets through tunnel ventilation. During daytime approximately 70% of aerosol mass concentrations are governed by coarse absorbing particles with a low Angström exponent (˜0.8) and a low single-scattering albedo (˜0.7). The corresponding aerosol density is about 2 g cm -3 and their complex refractive index at 355 nm is close to 1.56-0.035 i. The high absorption properties are linked to the significant proportion of iron oxides together with black carbon in braking systems. During the night, particles are mostly submicronic, thus presenting a greater Angström exponent (˜2). The aerosol density is lower (1.8 g cm -3) and their complex refractive index presents a lower imaginary part (1.58-0.013 i), associated to a stronger single-scattering albedo (˜0.85-0.90), mostly influenced by the ambient air. For the first time we have assessed the emission (deposition) rates in an underground station for PM 10, PM 2.5 and black carbon concentrations to be 3314 ± 781(-1164 ± 160), 1186 ± 358(-401 ± 66) and 167 ± 46(-25 ± 9) μg m -2 h -1, respectively.

  11. Uncertainty of Microphysics Schemes in CRMs

    NASA Astrophysics Data System (ADS)

    Tao, W. K.; van den Heever, S. C.; Wu, D.; Saleeby, S. M.; Lang, S. E.

    2015-12-01

    Microphysics is the framework through which to understand the links between interactive aerosol, cloud and precipitation processes. These processes play a critical role in the water and energy cycle. CRMs with advanced microphysics schemes have been used to study the interaction between aerosol, cloud and precipitation processes at high resolution. But, there are still many uncertainties associated with these microphysics schemes. This has arisen, in part, from the fact microphysical processes cannot be measured directly; instead, cloud properties, which can be measured, are and have been used to validate model results. The utilization of current and future global high-resolution models is rapidly increasing and are at what has been traditional CRM resolutions and are using microphysics schemes that were developed in traditional CRMs. A potential NASA satellite mission called the Cloud and Precipitation Processes Mission (CaPPM) is currently being planned for submission to the NASA Earth Science Decadal Survey. This mission could provide the necessary global estimates of cloud and precipitation properties with which to evaluate and improve dynamical and microphysical parameterizations and the feedbacks. In order to facilitate the development of this mission, CRM simulations have been conducted to identify microphysical processes responsible for the greatest uncertainties in CRMs. In this talk, we will present results from numerical simulations conducted using two CRMs (NU-WRF and RAMS) with different dynamics, radiation, land surface and microphysics schemes. Specifically, we will conduct sensitivity tests to examine the uncertainty of the some of the key ice processes (i.e. riming, melting, freezing and shedding) in these two-microphysics schemes. The idea is to quantify how these two different models' respond (surface rainfall and its intensity, strength of cloud drafts, LWP/IWP, convective-stratiform-anvil area distribution) to changes of these key ice

  12. Decadal Simulation and Comprehensive Evaluation of CESM/CAM5 with Advanced Chemistry, Aerosol Microphysics, and Aerosol-Cloud Interactions

    NASA Astrophysics Data System (ADS)

    He, J.; Glotfelty, T.; Zhang, Y.

    2013-12-01

    Community Earth System Model (CESM) is a global Earth system model that was developed by National Center for Atmospheric Research (NCAR) to simulate the entire Earth system by coupling physical climate system with chemistry, biogeochemistry, biology and human systems. It can also quantify the certainties and uncertainties in Earth system feedbacks on time scales up to centuries and longer. The Community Atmosphere Model version 5.1 (CAM5.1) is the atmosphere component of CESM version 1.0.5. CESM/CAM5.1 has been applied by NCAR to simulate climate change as part of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5). The IPCC-AR5 indicates that the uncertainties associated with cloud, aerosol, and their feedbacks, as well as uncertainties in near- and long-term projections are emerging issues to be addressed by the scientific community. CESM/CAM5.1 has been recently further developed and improved with advanced treatments for gas-phase chemistry, aerosol chemistry and dynamics, and aerosol-cloud interactions by North Carolina State University (NCSU) to reduce the uncertainties associated with those treatments in the model predictions. Our ultimate goal is to enhance CESM/CAM5's capability in representing current atmosphere and projecting future climate change. In this work, as the first step toward this goal, the NCSU's version of CESM/CAM5 with those advanced treatments is applied for 2001-2010, which will provide valuable information about the model's capability in capturing the decadal variation trend in climate and its potential in projecting future climate changes. The model simulation is conducted at a horizontal resolution of 0.9o × 1.25o and a vertical resolution of 30 layers. The simulation results based on 10-year average are evaluated comprehensively with a variety of datasets, including global surface observations of meteorological and radiative variables; satellite observations of the column mass of chemical species and

  13. Retrieval of the Eyjafjallajökull volcanic aerosol optical and microphysical properties from POLDER/PARASOL measurements

    NASA Astrophysics Data System (ADS)

    Waquet, F.; Peers, F.; Goloub, P.; Ducos, F.; Thieuleux, F.; Derimian, Y.; Riedi, J.; Tanré, D.

    2013-04-01

    Total and polarized radiances provided by the Polarization and Directionality of Earth Reflectances (POLDER) satellite sensor are used to retrieve the microphysical and optical properties of the volcanic plume observed during the Eyjafjallajökull volcano eruption in 2010, over cloud-free and cloudy ocean scenes. We selected two plume conditions, fresh aerosols near the sources (three cases) and a downwind volcanic plume observed over the North Sea 30 h after its injection into the atmosphere (aged aerosols). In the near-source conditions, the aerosol properties depend on the distance to the plume. Within the plume, aerosols are mainly non-spherical and in the coarse mode with an effective radius equal to 1.50 (± 0.15) μm and an Ångström Exponent (AE) close to 0.0. Far from the plume, in addition to the coarse mode, there are smaller particles retrieved in the accumulation mode suggesting a mixture of sulfate aerosols and volcanic dust, resulting in an AE around 0.8. The properties of the aerosols also depend on whether the plume is fresh or aged. For the downwind (aged) plume, if non-spherical coarse particles as well as some fine mode particles are still retrieved, the AE is smaller, around ~ 0.4. In addition, the real refractive index (RR) values are larger for the downwind plume (1.42 < RR < 1.58) than for the near-source plume (1.38 < RR < 1.48). The mean Single Scattering Albedo (SSA) retrieved at 0.865 μm was estimated at 0.97 over some parts of the downwind and near-source plumes; despite the low accuracy of our retrievals, the derived SSA values suggest that the ash particles are rather absorbing. To consider the particle shape, a combination of spheroid models is used. Although the employed model enabled accurate modeling of the POLDER signal in case of non-spherical ash, our approach failed to model the signal over the optically thickest parts of the near-source plume. The most probable reason for this is speculated to be the presence of ice

  14. Use of aerosol microphysical measurements to model IR backscatter in support of GLOBE

    NASA Technical Reports Server (NTRS)

    Patterson, Edward M.; Bowdle, David A.

    1991-01-01

    Data on the concentration and composition of free tropospheric aerosol over the Pacific Ocean, collected during the GAMETAG program in 1977-1978 (Davis, 1980 and Patterson et al., 1980) are used to model values of aerosol optical extinction coefficients (sigma) at two wavelengths (0.55 and 1 micron) and values of volume backscatter coefficients (beta) at four wavelengths (1 micron, 9.11 microns, 9.25 microns, and 10.6 microns) and to investigate the relationship between these parameters. The mass concentrations inferred from the GAMETAG measurements with optical particle spectrometers agreed with the results of simultaneous chemical measurements. The study of the relationships among the optical parameters indicates that visible and near-visible values of beta and sigma may be useful in predicting 9.11- and 10.6-micron backscatter.

  15. Use of aerosol microphysical measurements to model IR backscatter in support of GLOBE

    SciTech Connect

    Patterson, E.M. ); Bowdle, D.A. )

    1991-03-20

    The authors have used the GAMETAG Pacific mid-tropospheric aerosol data set to calculate aerosol optical extinction coefficients ({sigma}) at two wavelengths (0.55 {mu}m and 1 {mu}m) and volume backscatter coefficients ({beta}) at 4 wavelengths (1 {mu}m, 9.11 {mu}m, 9.25 {mu}m, and 10.6 {mu}m). At an altitude of 5 km over the Pacific, northern hemispheric mean values of {beta} for 10.6 {mu} are near 10{sup {minus}10} m{sup {minus}1}sr{sup {minus}1} at an altitude of 5 km, with southern hemispheric values approximately an order of magnitude lower. The 9.11 {mu}m values are roughly a factor of 3 higher than the 10.6 {mu}m values; 9.25 {mu}m values are approximately the same as 9.11 {mu}m values. For the data averaging times of 5-10 min are necessary for the calculated {beta} values as seen by a satellite lidar system. Under the assumptions of this study the molecular form of the sulfate aerosol is not a major determining factor in the calculated {beta} values at 10.6 {mu}m but could be significant at 9.11 {mu}m. A study of relationships among the optical parameters indicates that visible and near-visible values of {beta} and {sigma} may be useful in predicting 9.11- and 10.6 {mu}m backscatter, so that short wavelength aerosol data bases form satellites and Nd-YAG lidars may be useful in extending the data base of direct backscatter measurements at CO{sub 2} wavelengths.

  16. 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.

  17. Microphysical processes observed by X band polarimetric radars during the evolution of storm systems

    NASA Astrophysics Data System (ADS)

    Xie, Xinxin; Evaristo, Raquel; Troemel, Silke; Simmer, Clemens

    2014-05-01

    Polarimetric radars are now widely used for characterizing storm systems since they offer significant information for the improvement for atmospheric models and numerical weather prediction. Their observations allow a detailed insight into macro- and micro-physical processes during the spatial and temporal evolution of storm systems. In the frame of the initiative for High Definition Clouds and Precipitation for advancing Climate Prediction (HD(CP)2), which focuses on improving the accuracy of climate models in relation to cloud and precipitation processes, the HD(CP)2 Observational Prototype Experiment (HOPE) was designed to provide a critical model evaluation at scales covered by Large Eddy Simulation (LES) models, which in turn will be used to better understand sub-grid variability and microphysical properties and processes parameterized by larger scale models. Three X-band polarimetric radars deployed in Bonn (BoXPol) and in the vicinity of Juelich (JuXPol and KiXPol), Germany, were operated together with other instruments during the HOPE campaign, in order to obtain a holistic view of precipitation systems covering both macro- and microscopic processes. Given the variability of polarimetric moments observed by polarimetric radars, the corresponding microphysical processes occurring during the development of storm cells thus can be inferred accordingly. This study focuses on the microscopic processes of storm systems which were observed by RHI (range-height indicator) scans of the three X band radars. The two frequently observed microphysical processes during the HOPE campaign, coalescence and differential sedimentation, will be shown, and the evolution of droplet size distributions (DSDs) will be also analyzed. The associated DSDs which are retrieved using radar measured polarimetric moments are further verified by the polarimetric forward operator where the assumptions of non-spherical hydrometeors have been embedded. The results indicate that the estimated

  18. Vertical distribution of optical and microphysical properties of smog aerosols measured by multi-wavelength polarization lidar in Xi'an, China

    NASA Astrophysics Data System (ADS)

    Di, Huige; Hua, Hangbo; Cui, Yan; Hua, Dengxin; He, Tingyao; Wang, Yufeng; Yan, Qing

    2017-02-01

    In this study, a multi-wavelength polarization lidar was developed at the Lidar Center for Atmosphere Remote Sensing, in Xi'an, China to study the vertical distribution of the optical and microphysical properties of smog aerosols. To better understand smog, two events with different haze conditions observed in January 2015 were analyzed in detail. Using these data, we performed a vertical characterization of smog evolution using the lidar range-squared-corrected signal and the aerosol depolarization ratio. Using inversion with regularization, we retrieved the vertical distribution of aerosol microphysical properties, including volume size distribution, volume concentration, number concentration and effective radius. We also used the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model to analyze aerosol sources during the two episodes. Our results show that the most polluted area in the lower troposphere during smog episodes is located below a height of 1 km above the ground level; under more severe smog conditions, it can be below 0.5 km. In the case of severe smog, we found a large number of spherical and fine particles concentrated in the very low troposphere, even below 0.5 km. Surprisingly, a dust layer with a slight depolarization ratio was observed above the smog layer.

  19. Decadal simulation and comprehensive evaluation of CESM/CAM5.1 with advanced chemistry, aerosol microphysics, and aerosol-cloud interactions

    NASA Astrophysics Data System (ADS)

    He, Jian; Zhang, Yang; Glotfelty, Tim; He, Ruoying; Bennartz, Ralf; Rausch, John; Sartelet, Karine

    2015-03-01

    Earth system models have been used for climate predictions in recent years due to their capabilities to include biogeochemical cycles, human impacts, as well as coupled and interactive representations of Earth system components (e.g., atmosphere, ocean, land, and sea ice). In this work, the Community Earth System Model (CESM) with advanced chemistry and aerosol treatments, referred to as CESM-NCSU, is applied for decadal (2001-2010) global climate predictions. A comprehensive evaluation is performed focusing on the atmospheric component—the Community Atmosphere Model version 5.1 (CAM5.1) by comparing simulation results with observations/reanalysis data and CESM ensemble simulations from the Coupled Model Intercomparison Project phase 5 (CMIP5). The improved model can predict most meteorological and radiative variables relatively well with normalized mean biases (NMBs) of -14.1 to -9.7% and 0.7-10.8%, respectively, although temperature at 2 m (T2) is slightly underpredicted. Cloud variables such as cloud fraction (CF) and precipitating water vapor (PWV) are well predicted, with NMBs of -10.5 to 0.4%, whereas cloud condensation nuclei (CCN), cloud liquid water path (LWP), and cloud optical thickness (COT) are moderately-to-largely underpredicted, with NMBs of -82.2 to -31.2%, and cloud droplet number concentration (CDNC) is overpredictd by 26.7%. These biases indicate the limitations and uncertainties associated with cloud microphysics (e.g., resolved clouds and subgrid-scale cumulus clouds). Chemical concentrations over the continental U.S. (CONUS) (e.g., SO42-, Cl-, OC, and PM2.5) are reasonably well predicted with NMBs of -12.8 to -1.18%. Concentrations of SO2, SO42-, and PM10 are also reasonably well predicted over Europe with NMBs of -20.8 to -5.2%, so are predictions of SO2 concentrations over the East Asia with an NMB of -18.2%, and the tropospheric ozone residual (TOR) over the globe with an NMB of -3.5%. Most meteorological and radiative variables

  20. A 2D Microphysical Analysis of Aerosol Nucleation in the Polar Winter Stratosphere: Implications for H2SO4 Photolysis and Nucleation Mechanisms

    NASA Technical Reports Server (NTRS)

    Mills, Michael J.; Toon, Owen B.; Mills, Michael J.; Solomon, Susan

    1997-01-01

    Each spring a layer of small particles forms between 20 and 30 km in the polar regions. Results are presented from a 2D microphysical model of sulfate aerosol, which provide the first self-consistent explanation of the observed "CN layer." Photochemical conversion of sulfuric acid to SO2 in the upper stratosphere and mesosphere is necessary for this layer to form. Recent laboratory measurements of H2SO4 and SO3 photolysis rates are consistent with such conversion, though an additional source of SO2 may be required. Nucleation throughout the polar winter extends the top of the aerosol layer to higher altitudes, despite strong downward transport of ambient air. This finding may be important to heterogeneous chemistry at the top of the aerosol layer in polar winter and spring.

  1. Photopolarimetry of planetary atmospheres: what observational data are essential for a unique retrieval of aerosol microphysics?

    NASA Astrophysics Data System (ADS)

    Dlugach, Janna M.; Mishchenko, Michael I.

    2008-02-01

    We analyse the results of computations of the intensity and degree of linear polarization of diffusely reflected sunlight for the centre of a planetary disc in the phase-angle range 0° < α < 90°. The computations are performed using numerically exact T-matrix and vector radiative-transfer codes for several alternative models of the Jovian cloud layer derived previously from ground-based spectropolarimetric observations at phase angles α < 11°. Our results show that although these models reproduce the existing observational data equally well, they start to show significant polarization differences at phase angles α >= 12°. Thus, using Jupiter as a `proving ground', we conclude that only polarimetric data obtained over a wide range of phase angles (i.e. from spacecraft) may provide definitive constraints on aerosol shape and, as a consequence, ameliorate the ill-posed nature of the inverse remote-sensing problem.

  2. Impact of uncertainties in parameterized cloud-microphysical processes on the simulated development of an idealized 2-D squall line

    NASA Astrophysics Data System (ADS)

    Michelson, Sara; Bao, Jian-Wen; Grell, Evelyn

    2016-04-01

    In this study, numerical model simulations of an idealized 2-D squall line are investigated using microphysics budget analysis. Four commonly-used microphysics schemes of various complexity are used in the simulations. Diagnoses of the source and sink terms of the hydrometeor budget equations reveal that the differences related to the assumptions of hydrometeor size-distributions between the schemes lead to the differences in the simulations due to the net effect of various microphysical processes on the interaction between latent heating/evaporative cooling and flow dynamics as the squall line develops. Results from this study also highlight the possibility that the advantage of double-moment formulations can be overshadowed by the uncertainties in the spectral definition of individual hydrometeor categories and spectrum-dependent microphysical processes.

  3. Study of aerosol microphysical properties profiles retrieved from ground-based remote sensing and aircraft in-situ measurements during a Saharan dust event

    NASA Astrophysics Data System (ADS)

    Granados-Muñoz, M. J.; Bravo-Aranda, J. A.; Baumgardner, D.; Guerrero-Rascado, J. L.; Pérez-Ramírez, D.; Navas-Guzmán, F.; Veselovskii, I.; Lyamani, H.; Valenzuela, A.; Olmo, F. J.; Titos, G.; Andrey, J.; Chaikovsky, A.; Dubovik, O.; Gil-Ojeda, M.; Alados-Arboledas, L.

    2015-09-01

    In this work we present an analysis of mineral dust optical and microphysical properties obtained from different retrieval techniques applied to active and passive remote sensing measurements, including a comparison with simultaneous in-situ aircraft measurements. Data were collected in a field campaign performed during a mineral dust outbreak a Granada, Spain, experimental site (37.16° N, 3.61° W, 680 m a.s.l.) on the 27 June 2011. Column-integrated properties are provided by sun- and star-photometry which allows a continuous evaluation of the mineral dust optical properties during both day and night-time. Both the Linear Estimation and AERONET (Aerosol Robotic Network) inversion algorithms are applied for the retrieval of the column-integrated microphysical particle properties. In addition, vertically-resolved microphysical properties are obtained from a multi-wavelength Raman lidar system included in EARLINET (European Aerosol Research Lidar Network), by using both LIRIC (Lidar Radiometer Inversion Code) algorithm during daytime and an algorithm applied to the Raman measurements based on the regularization technique during night-time. LIRIC retrievals reveal several dust layers between 3 and 5 km a.s.l. with volume concentrations of the coarse spheroid mode up to 60 μm3 cm-3. The combined use of the regularization and LIRIC methods reveals the night-to-day evolution of the vertical structure of the mineral dust microphysical properties and offers complementary information to that from column-integrated variables retrieved from passive remote sensing. Additionally, lidar depolarization profiles and LIRIC retrieved volume concentration are compared with aircraft in-situ measurements. This study presents for the first time a comparison of both volume concentration and dust particle polarization ratios measured with in-situ and remote sensing techniques. Results for the depolarization measurements in the dust layer indicate reasonable agreement within the

  4. Impacts of cloud microphysics on trade wind cumulus: which cloud microphysics processes contribute to the diversity in a large eddy simulation?

    NASA Astrophysics Data System (ADS)

    Sato, Yousuke; Nishizawa, Seiya; Yashiro, Hisashi; Miyamoto, Yoshiaki; Kajikawa, Yoshiyuki; Tomita, Hirofumi

    2015-12-01

    This study investigated the impact of several cloud microphysical schemes on the trade wind cumulus in the large eddy simulation model. To highlight the differences due to the cloud microphysical component, we developed a fully compressible large eddy simulation model, which excluded the implicit scheme and approximations as much as possible. The three microphysical schemes, the one-moment bulk, two-moment bulk, and spectral bin schemes were used for sensitivity experiments in which the other components were fixed. Our new large eddy simulation model using a spectral bin scheme successfully reproduced trade wind cumuli, and reliable model performance was confirmed. Results of the sensitivity experiments indicated that precipitation simulated by the one-moment bulk scheme started earlier, and its total amount was larger than that of the other models. By contrast, precipitation simulated by the two-moment scheme started late, and its total amount was small. These results support those of a previous study. The analyses revealed that the expression of two processes, (1) the generation of cloud particles and (2) the conversion from small droplets to raindrops, were crucial to the results. The fast conversion from cloud to rain and the large amount of newly generated cloud particles at the cloud base led to evaporative cooling and subsequent stabilization in the sub-cloud layer. The latent heat released at higher layers by the condensation of cloud particles resulted in the development of the boundary layer top height.

  5. The role of microphysical processes on the mesoscale simulation over the complex terrain, the Himalayas

    NASA Astrophysics Data System (ADS)

    Shrestha, R. K.; Gallagher, M. W.; Connolly, P.

    2010-12-01

    The objective of this study is to evaluate the impact of the four different cloud microphysical schemes (WSM3, WSM6, Morrison double moment and Lin scheme) within the Weather Research and Forecasting model (WRF), as part of simulations of mesoscale weather systems across complex terrain in the Nepalese Himalayas. The Himalayas is characterized by a complex and rugged topography, with altitudes varying e.g. 70m in Southeastern Nepal, to the highest peak of the world, 8850m (Mt. Everest), and which extends from West to East covering many South and Central Asian countries: Afghanistan, Pakistan, China, India, Nepal, Bhutan, and Myanmar. Circulation in such a complex environment is complicated due to obstruction of flows by mountain ranges which in turn have wide ranging effects on cloud and rain formation and distribution. Monsoon rain is intrinsically linked to people’s daily life across the South Asia since more than 80% people depend on agriculture and majority of the agricultural systems are rainfall dependent. Modeling of the key microphysical process in this complex terrain provides insight into the general understanding of the processes and their spatial patterns, however there are many uncertainties in general. These uncertainties are even more pronounced when such models are applied to the complex terrain characteristic of the Himalayas. Numerical experiments are designed using the WRF model, with three nested domains (27, 9 and 3 km grid spacing). The performance of the four categories of microphysical schemes is examined in model experiments for (i) monsoon onset, (ii) monsoon decay and (iii) winter rainfall. The simulated results are compared with limited observed meteorological parameters such as rainfall, temperature, wind speed and wind direction, from ground-based meteorological stations situated within the high resolution (3km x 3km) domain. Results show that a) Simulated rainfall is very sensitive to the chosen microphysical scheme with rainfall

  6. Simulations of Hurricane Nadine (2012) during HS3 Using the NASA Unified WRF with Aerosol-Cloud Microphysics-Radiation Coupling

    NASA Astrophysics Data System (ADS)

    Shi, J. J.; Braun, S. A.; Sippel, J. A.; Tao, W. K.; Tao, Z.

    2014-12-01

    The impact of the SAL on the development and intensification of hurricanes has garnered significant attention in recent years. Many past studies have shown that synoptic outbreaks of Saharan dust, which usually occur from late spring to early fall and can extend from western Africa across the Atlantic Ocean into the Caribbean, can have impacts on hurricane genesis and subsequent intensity change. The Hurricane and Severe Storm Sentinel (HS3) mission is a multiyear NASA field campaign with the goal of improving understanding of hurricane formation and intensity change. One of HS3's primary science goals is to obtain measurements to help determine the extent to which the Saharan air layer impacts storm intensification. HS3 uses two of NASA's unmanned Global Hawk aircrafts equipped with three instruments each to measure characteristics of the storm environment and inner core. The Goddard microphysics and longwave/shortwave schemes in the NASA Unified Weather Research and Forecasting (NU-WRF) model have been coupled in real-time with the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model in WRF-Chem to account for the direct (radiation) and indirect (microphysics) impact. NU-WRF with interactive aerosol-cloud-radiation physics is used to generate 30-member ensemble simulations of Nadine (2012) with and without the aerosol interactions. Preliminary conclusions related to the impact of the SAL on the evolution of Nadine from the HS3 observations and model output will be described.

  7. 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.

  8. Intercomparison of Pulsed Lidar Data with Flight Level CW Lidar Data and Modeled Backscatter from Measured Aerosol Microphysics Near Japan and Hawaii

    NASA Technical Reports Server (NTRS)

    Cutten, D. R.; Spinhirne, J. D.; Menzies, R. T.; Bowdle, D. A.; Srivastava, V.; Pueschel, R. F.; Clarke, A. D.; Rothermel, J.

    1998-01-01

    Aerosol backscatter coefficient data were examined from two nights near Japan and Hawaii undertaken during NASA's Global Backscatter Experiment (GLOBE) in May-June 1990. During each of these two nights the aircraft traversed different altitudes within a region of the atmosphere defined by the same set of latitude and longitude coordinates. This provided an ideal opportunity to allow flight level focused continuous wave (CW) lidar backscatter measured at 9.11-micron wavelength and modeled aerosol backscatter from two aerosol optical counters to be compared with pulsed lidar aerosol backscatter data at 1.06- and 9.25-micron wavelengths. The best agreement between all sensors was found in the altitude region below 7 km, where backscatter values were moderately high at all three wavelengths. Above this altitude the pulsed lidar backscatter data at 1.06- and 9.25-micron wavelengths were higher than the flight level data obtained from the CW lidar or derived from the optical counters, suggesting sample volume effects were responsible for this. Aerosol microphysics analysis of data near Japan revealed a strong sea-salt aerosol plume extending upward from the marine boundary layer. On the basis of sample volume differences, it was found that large particles were of different composition compared with the small particles for low backscatter conditions.

  9. A comparative study of aerosol microphysical properties retrieved from ground-based remote sensing and aircraft in situ measurements during a Saharan dust event

    NASA Astrophysics Data System (ADS)

    José Granados-Muñoz, María; Bravo-Aranda, Juan Antonio; Baumgardner, Darrel; Guerrero-Rascado, Juan Luis; Pérez-Ramírez, Daniel; Navas-Guzmán, Francisco; Veselovskii, Igor; Lyamani, Hassan; Valenzuela, Antonio; José Olmo, Francisco; Titos, Gloria; Andrey, Javier; Chaikovsky, Anatoli; Dubovik, Oleg; Gil-Ojeda, Manuel; Alados-Arboledas, Lucas

    2016-03-01

    In this work we present an analysis of aerosol microphysical properties during a mineral dust event taking advantage of the combination of different state-of-the-art retrieval techniques applied to active and passive remote sensing measurements and the evaluation of some of those techniques using independent data acquired from in situ aircraft measurements. Data were collected in a field campaign performed during a mineral dust outbreak at the Granada, Spain, experimental site (37.16° N, 3.61° W, 680 m a.s.l.) on 27 June 2011. Column-integrated properties are provided by sun- and star-photometry, which allows for a continuous evaluation of the mineral dust optical properties during both day and nighttime. Both the linear estimation and AERONET (Aerosol Robotic Network) inversion algorithms are applied for the retrieval of the column-integrated microphysical particle properties. In addition, vertically resolved microphysical properties are obtained from a multi-wavelength Raman lidar system included in EARLINET (European Aerosol Research Lidar Network), by using both LIRIC (Lidar Radiometer Inversion Code) algorithm during daytime and an algorithm applied to the Raman measurements based on the regularization technique during nighttime. LIRIC retrievals reveal the presence of dust layers between 3 and 5 km a.s.l. with volume concentrations of the coarse spheroid mode up to 60 µm3 cm-3. The combined use of the regularization and LIRIC methods reveals the night-to-day evolution of the vertical structure of the mineral dust microphysical properties and offers complementary information to that from column-integrated variables retrieved from passive remote sensing. Additionally, lidar depolarization profiles and LIRIC retrieved volume concentration are compared with aircraft in situ measurements. This study presents for the first time a comparison of the total volume concentration retrieved with LIRIC with independent in situ measurements, obtaining agreement within

  10. Microphysics, Radiation and Surface Processes in the Goddard Cumulus Ensemble (GCE) Model

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Simpson, J.; Baker, D.; Braun, S.; Chou, M.-D.; Ferrier, B.; Johnson, D.; Khain, A.; Lang, S.; Lynn, B.

    2001-01-01

    The response of cloud systems to their environment is an important link in a chain of processes responsible for monsoons, frontal depression, El Nino Southern Oscillation (ENSO) episodes and other climate variations (e.g., 30-60 day intra-seasonal oscillations). Numerical models of cloud properties provide essential insights into the interactions of clouds with each other, with their surroundings, and with land and ocean surfaces. Significant advances are currently being made in the modeling of rainfall and rain-related cloud processes, ranging in scales from the very small up to the simulation of an extensive population of raining cumulus clouds in a tropical- or midlatitude-storm environment. The Goddard Cumulus Ensemble (GCE) model is a multi-dimensional nonhydrostatic dynamic/microphysical cloud resolving model. It has been used to simulate many different mesoscale convective systems that occurred in various geographic locations. In this paper, recent GCE model improvements (microphysics, radiation and surface processes) will be described as well as their impact on the development of precipitation events from various geographic locations. The performance of these new physical processes will be examined by comparing the model results with observations. In addition, the explicit interactive processes between cloud, radiation and surface processes will be discussed.

  11. Overview of the Cumulus Humilis Aerosol Processing Study.

    SciTech Connect

    Berg, L. K.; Berkowitz, C. M.; Ogren, J. A.; Hostetler, C. A.; Ferrare, R. A.; Dubey, M.; Andrews, E.; Coulter, R. L.; Hair, J. W.; Hubbe, J. M.Lee, Y. N.; Mazzoleni, C; Olfert, J; Springston, SR; Environmental Science Division; PNNL; NOAA Earth System Research Lab.; NASA Langley Research Center; LANL; BNL; Univ.of Alberta; Univ. of Colorado

    2009-11-01

    Aerosols influence climate directly by scattering and absorbing radiation and indirectly through their influence on cloud microphysical and dynamical properties. The Intergovernmental Panel on Climate Change (IPCC) concluded that the global radiative forcing due to aerosols is large and in general cools the planet. But the uncertainties in these estimates are also large due to our poor understanding of many of the important processes related to aerosols and clouds. To address this uncertainty an integrated strategy for addressing issues related to aerosols and aerosol processes was proposed. Using this conceptual framework, the Cumulus Humilis Aerosol Processing Study (CHAPS) is a stage 1 activity, that is, a detailed process study. The specific focus of CHAPS was to provide concurrent observations of the chemical composition of the activated [particles that are currently serving as cloud condensation nuclei (CCN)] and nonactivated aerosols, the scattering and extinction profiles, and detailed aerosol and droplet size spectra in the vicinity of Oklahoma City, Oklahoma, during June 2007. Numerous campaigns have examined aerosol properties downwind from large pollution sources, including the Megacity Initiative: Local and Global Research Observations (MILAGRO) campaign and the two of the three Aerosol Characterization Experiments, ACE-2 and ACE-Asia. Other studies conducted near cities have examined changes in both aerosols and clouds downwind of urban areas. For example wintertime stratiform clouds associated with the urban plumes of Denver, Colorado, and Kansas City, Missouri, have a larger number concentration and smaller median volume diameter of droplets than clouds that had not been affected by the urban plume. Likewise, a decrease in precipitation in polluted regions along the Front Range of the Rocky Mountains was discovered. In a modeling study, it was found that precipitation downwind of urban areas may be influenced by changes in aerosols as well as the

  12. Factors Affecting the Evolution of Hurricane Erin and the Distributions of Hydrometeors: Role of Microphysical Processes

    NASA Technical Reports Server (NTRS)

    McFarquhar, Greg M.; Zhang, Henian; Dudhia, Jimy; Halverson, Jeffrey B.; Heymsfield, Gerald; Hood, Robbie; Marks, Frank, Jr.

    2003-01-01

    Fine-resolution simulations of Hurricane Erin 2001 are conducted using the Penn State University/National Center for Atmospheric Research mesoscale model version 3.5 to investigate the role of thermodynamic, boundary layer and microphysical processes in Erin's growth and maintenance, and their effects on the horizontal and vertical distributions of hydrometeors. Through comparison against radar, radiometer, and dropsonde data collected during the Convection and Moisture Experiment 4, it is seen that realistic simulations of Erin are obtained provided that fine resolution simulations with detailed representations of physical processes are conducted. The principle findings of the study are as follows: 1) a new iterative condensation scheme, which limits the unphysical increase of equivalent potential temperature associated with most condensation schemes, increases the horizontal size of the hurricane, decreases its maximum rainfall rate, reduces its intensity, and makes its eye more moist; 2) in general, microphysical parameterization schemes with more categories of hydrometeors produce more intense hurricanes, larger hydrometeor mixing ratios, and more intense updrafts and downdrafts; 3) the choice of coefficients describing hydrometeor fall velocities has as big of an impact on the hurricane simulations as does choice of microphysical parameterization scheme with no clear relationship between fall velocity and hurricane intensity; and 4) in order for a tropical cyclone to adequately intensify, an advanced boundary layer scheme (e.g., Burk-Thompson scheme) must be used to represent boundary layer processes. The impacts of varying simulations on the horizontal and vertical distributions of different categories of hydrometeor species, on equivalent potential temperature, and on storm updrafts and downdrafts are examined to determine how the release of latent heat feedbacks upon the structure of Erin. In general, all simulations tend to overpredict precipitation rate

  13. 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

  14. A novel approach for the characterisation of transport and optical properties of aerosol particles near sources - Part II: Microphysics-chemistry-transport model development and application

    NASA Astrophysics Data System (ADS)

    Valdebenito B, Álvaro M.; Pal, Sandip; Behrendt, Andreas; Wulfmeyer, Volker; Lammel, Gerhard

    2011-06-01

    A new high-resolution microphysics-chemistry-transport model (LES-AOP) was developed and applied for the investigation of aerosol transformation and transport in the vicinity of a livestock facility in northern Germany (PLUS1 field campaign). The model is an extension of a Large-Eddy Simulation (LES) model. The PLUS1 field campaign included the first deployment of the new eye-safe scanning aerosol lidar system of the University of Hohenheim. In a combined approach, model and lidar results were used to characterise a faint aerosol source. The farm plume structure was investigated and the absolute value of its particle backscatter coefficient was determined. Aerosol optical properties were predicted on spatial and temporal resolutions below 100 m and 1 min, upon initialisation by measured meteorological and size-resolved particulate matter mass concentration and composition data. Faint aerosol plumes corresponding to a particle backscatter coefficient down to 10 -6 sr -1 m -1 were measured and realistically simulated. Budget-related quantities such as the emission flux and change of the particulate matter mass, were estimated from model results and ground measurements.

  15. Profiling of aerosol microphysical properties at several EARLINET/AERONET sites during the July 2012 ChArMEx/EMEP campaign

    NASA Astrophysics Data System (ADS)

    José Granados-Muñoz, María; Navas-Guzmán, Francisco; Guerrero-Rascado, Juan Luis; Bravo-Aranda, Juan Antonio; Binietoglou, Ioannis; Nepomuceno Pereira, Sergio; Basart, Sara; María Baldasano, José; Belegante, Livio; Chaikovsky, Anatoli; Comerón, Adolfo; D'Amico, Giuseppe; Dubovik, Oleg; Ilic, Luka; Kokkalis, Panos; Muñoz-Porcar, Constantino; Nickovic, Slobodan; Nicolae, Doina; José Olmo, Francisco; Papayannis, Alexander; Pappalardo, Gelsomina; Rodríguez, Alejandro; Schepanski, Kerstin; Sicard, Michaël; Vukovic, Ana; Wandinger, Ulla; Dulac, François; Alados-Arboledas, Lucas

    2016-06-01

    The simultaneous analysis of aerosol microphysical properties profiles at different European stations is made in the framework of the ChArMEx/EMEP 2012 field campaign (9-11 July 2012). During and in support of this campaign, five lidar ground-based stations (Athens, Barcelona, Bucharest, Évora, and Granada) performed 72 h of continuous lidar measurements and collocated and coincident sun-photometer measurements. Therefore it was possible to retrieve volume concentration profiles with the Lidar Radiometer Inversion Code (LIRIC). Results indicated the presence of a mineral dust plume affecting the western Mediterranean region (mainly the Granada station), whereas a different aerosol plume was observed over the Balkans area. LIRIC profiles showed a predominance of coarse spheroid particles above Granada, as expected for mineral dust, and an aerosol plume composed mainly of fine and coarse spherical particles above Athens and Bucharest. Due to the exceptional characteristics of the ChArMEx database, the analysis of the microphysical properties profiles' temporal evolution was also possible. An in-depth analysis was performed mainly at the Granada station because of the availability of continuous lidar measurements and frequent AERONET inversion retrievals. The analysis at Granada was of special interest since the station was affected by mineral dust during the complete analyzed period. LIRIC was found to be a very useful tool for performing continuous monitoring of mineral dust, allowing for the analysis of the dynamics of the dust event in the vertical and temporal coordinates. Results obtained here illustrate the importance of having collocated and simultaneous advanced lidar and sun-photometer measurements in order to characterize the aerosol microphysical properties in both the vertical and temporal coordinates at a regional scale. In addition, this study revealed that the use of the depolarization information as input in LIRIC in the stations of Bucharest,

  16. The importance of aerosol composition and mixing state on predicted CCN concentration and the variation of the importance with atmospheric processing of aerosol

    SciTech Connect

    Wang, J.; Cubison, M.; Aiken, A.; Jimenez, J.; Collins, D.; Gaffney, J.; Marley, N.

    2010-03-15

    -independent particle composition leads to substantial overestimation of CCN concentration for freshly emitted aerosols in early morning, but can reasonably predict the CCN concentration after the aerosols underwent atmospheric processing for several hours. This analysis employing various simplifications provides insights into the essential information of particle chemical composition that needs to be represented in models to adequately predict CCN concentration and cloud microphysics.

  17. Improved identification of the solution space of aerosol microphysical properties derived from the inversion of profiles of lidar optical data, part 2: simulations with synthetic optical data.

    PubMed

    Kolgotin, Alexei; Müller, Detlef; Chemyakin, Eduard; Romanov, Anton

    2016-12-01

    We developed a mathematical scheme that allows us to improve retrieval products obtained from the inversion of multiwavelength Raman/HSRL lidar data, commonly dubbed "3 backscatter+2 extinction" (3β+2α) lidar. This scheme works independently of the automated inversion method that is currently being developed in the framework of the Aerosol-Cloud-Ecosystem (ACE) mission and which is successfully applied since 2012 [Atmos. Meas. Tech.7, 3487 (2014)10.5194/amt-7-3487-2014; "Comparison of aerosol optical and microphysical retrievals from HSRL-2 and in-situ measurements during DISCOVER-AQ 2013 (California and Texas)," in International Laser Radar Conference, July 2015, paper PS-C1-14] to data collected with the first airborne multiwavelength 3β+2α high spectral resolution lidar (HSRL) developed at NASA Langley Research Center. The mathematical scheme uses gradient correlation relationships we presented in part 1 of our study [Appl. Opt.55, 9839 (2016)APOPAI0003-693510.1364/AO.55.009839] in which we investigated lidar data products and particle microphysical parameters from one and the same set of optical lidar profiles. For an accurate assessment of regression coefficients that are used in the correlation relationships we specially designed the proximate analysis method that allows us to search for a first-estimate solution space of particle microphysical parameters on the basis of a look-up table. The scheme works for any shape of particle size distribution. Simulation studies demonstrate a significant stabilization of the various solution spaces of the investigated aerosol microphysical data products if we apply this gradient correlation method in our traditional regularization technique. Surface-area concentration can be estimated with an uncertainty that is not worse than the measurement error of the underlying extinction coefficients. The retrieval uncertainty of the effective radius is as large as ±0.07  μm for fine mode particles and approximately

  18. Analysis of the sensitivity of thermal infrared nadir satellite observations to the chemical and micro-physical properties of upper tropospheric-lower stratospheric sulphate aerosols

    NASA Astrophysics Data System (ADS)

    Sellitto, Pasquale; Sèze, Geneviève; Legras, Bernard

    2015-04-01

    Secondary sulphate aerosols are the predominant typology of aerosols in the upper troposphere/lower stratosphere (UTLS), and can have an important impact on radiative transfer and climate, cirrus formation and chemistry in the UTLS. Despite their importance, the satellite observation at the regional scale of sulphate aerosols in the UTLS is limited. In this work, we address the sensitivity of the thermal infrared satellite observations to secondary sulphate aerosols in the UTLS. The absorption properties of sulphuric acid/water droplets, for different sulphuric acid mixing ratios and temperatures, are systematically analysed. The absorption coefficients are derived by means of a Mie code, using refractive indexes taken from the GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphériques : Management and Study of Spectroscopic Information) spectroscopic database and log-normal size distributions with different effective radii and number concentrations. IASI (Infrared Atmospheric Sounding Interferometer) and SEVIRI (Spinning Enhanced Visible and Infrared Imager) pseudo-observations are generated using forward radiative transfer calculations performed with the 4A (Automatized Atmospheric Absorption Atlas) radiative transfer model, to estimate the impact of the absorption of idealized aerosol layers, at typical UTLS conditions, on the radiance spectra observed by these simulated satellite instruments. We found a marked spectral signature of these aerosol layers between 700 and 1200 cm-1, due to the absorption bands of the sulphate and bi-sulphate ions and the undissociated sulphuric acid, with absorption peaks at 1170 and 905 cm-1. Micro-windows with a sensitivity to chemical and micro-physical properties of the sulphate aerosol layer are identified, and the role of interfering species, and temperature and water vapour profile is discussed.

  19. Microphysics, Radiation and Surface Processes in the Goddard Cumulus Ensemble (GCE) Model

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Starr, David (Technical Monitor)

    2002-01-01

    One of the most promising methods to test the representation of cloud processes used in climate models is to use observations together with Cloud Resolving Models (CRMs). The CRMs use more sophisticated and realistic representations of cloud microphysical processes, and they can reasonably well resolve the time evolution, structure, and life cycles of clouds and cloud systems (size about 2-200 km). The CRMs also allow explicit interaction between out-going longwave (cooling) and in-coming solar (heating) radiation with clouds. Observations can provide the initial conditions and validation for CRM results. The Goddard Cumulus Ensemble (GCE) Model, a CRM, has been developed and improved at NASA/Goddard Space Flight Center over the past two decades. The GCE model has been used to understand the following: 1) water and energy cycles and their roles in the tropical climate system; 2) the vertical redistribution of ozone and trace constituents by individual clouds and well organized convective systems over various spatial scales; 3) the relationship between the vertical distribution of latent heating (phase change of water) and the large-scale (pre-storm) environment; 4) the validity of assumptions used in the representation of cloud processes in climate and global circulation models; and 5) the representation of cloud microphysical processes and their interaction with radiative forcing over tropical and midlatitude regions. Four-dimensional cloud and latent heating fields simulated from the GCE model have been provided to the TRMM Science Data and Information System (TSDIS) to develop and improve algorithms for retrieving rainfall and latent heating rates for TRMM and the NASA Earth Observing System (EOS). More than 90 referred papers using the GCE model have been published in the last two decades. Also, more than 10 national and international universities are currently using the GCE model for research and teaching. In this talk, five specific major GCE improvements: (1

  20. 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.

  1. Performance of McRAS-AC in the GEOS-5 AGCM: Part 1, Aerosol-Activated Cloud Microphysics, Precipitation, Radiative Effects, and Circulation

    NASA Technical Reports Server (NTRS)

    Sud, Y. C.; Lee, D.; Oreopoulos, L.; Barahona, D.; Nenes, A.; Suarez, M. J.

    2012-01-01

    A revised version of the Microphysics of clouds with Relaxed Arakawa-Schubert and Aerosol-Cloud interaction (McRAS-AC), including, among others, the Barahona and Nenes ice nucleation parameterization, is implemented in the GEOS-5 AGCM. Various fields from a 10-year long integration of the AGCM with McRAS-AC were compared with their counterparts from an integration of the baseline GEOS-5 AGCM, and with satellite data as observations. Generally using McRAS-AC reduced biases in cloud fields and cloud radiative effects are much better over most of the regions of the Earth. Two weaknesses are identified in the McRAS-AC runs, namely, too few cloud particles around 40S-60S, and too high cloud water path during northern hemisphere summer over the Gulf Stream and North Pacific. Sensitivity analyses showed that these biases potentially originated from biases in the aerosol input. The first bias is largely eliminated in a sensitivity test using 50% smaller aerosol particles, while the second bias is much reduced when interactive aerosol chemistry was turned on. The main drawback of McRAS-AC is dearth of low-level marine stratus clouds, probably due to lack of dry-convection, not yet implemented into the cloud scheme. Despite these biases, McRAS-AC does simulate realistic clouds and their optical properties that can improve with better aerosol-input and thereby has the potential to be a valuable tool for climate modeling research because of its aerosol indirect effect simulation capabilities involving prediction of cloud particle number concentration and effective particle size for both convective and stratiform clouds is quite realistic.

  2. Properties of aerosol processed by ice clouds

    NASA Astrophysics Data System (ADS)

    Rudich, Y.; Adler, G.; Moise, T.; Erlick-Haspel, C.

    2012-12-01

    We suggest that highly porous aerosol (HPA) can form in the upper troposphere/lower stratosphere when ice particles encounter sub-saturation leading to ice sublimation similar to freeze drying. This process can occur at the lower layers of cirrus clouds (few km), at anvils of high convective clouds and thunderstorms, in clouds forming in atmospheric gravitational waves, in contrails and in high convective clouds injecting to the stratosphere. A new experimental system that simulates freeze drying of proxies for atmospheric aerosol at atmospheric pressure was constructed and various proxies for atmospheric soluble aerosol were studied. The properties of resulting HPA were characterized by various methods. It was found that the resulting aerosol have larger sizes (extent depends on substance and mixing), lower density (largevoid fraction), lower optical extinction and higher CCN activity and IN activity. Implication of HPA's unique properties and their atmospheric consequences to aerosol processing in ice clouds and to cloud cycles will be discussed.

  3. Assessment of aerosol optical and micro-physical features retrieved from direct and diffuse solar irradiance measurements from Skyradiometer at a high altitude station at Merak: Assessment of aerosol optical features from Merak.

    PubMed

    Ningombam, Shantikumar S; Srivastava, A K; Bagare, S P; Singh, R B; Kanawade, V P; Dorjey, Namgyal

    2015-11-01

    Optical and micro-physical features of aerosol are reported using Skyradiometer (POM-01L, Prede, Japan) observations taken from a high-altitude station Merak, located in north-eastern Ladakh of the western trans-Himalayas region during January 2011 to December 2013. The observed daily mean aerosol optical depth (AOD, at 500 nm) at the site varied from 0.01 to 0.14. However, 75 % of the observed AOD lies below 0.05 during the study period. Seasonal peaks of AOD occurred in spring as 0.06 and minimum in winter as 0.03 which represents the aged background aerosols at the site. Yearly mean AOD at 500 nm is found to be around 0.04 and inter-annual variations of AOD is very small (nearly ±0.01). Angstrom exponent (a) varied seasonally from 0.73 in spring to 1.5 in autumn. About 30 % of the observed a lies below 0.8 which are the indicative for the presence of coarse-mode aerosols at the site. The station exhibits absorbing aerosol features which prominently occurred during spring and that may be attributed by the transported anthropogenic aerosol from Indo-Gangatic Plain (IGP). Results were well substantiated with the air mass back-trajectory analysis. Furthermore, seasonal mean of single scattering albedo (SSA at 500 nm) varied from of 0.94 to 0.98 and a general increasing trend is noticed from 400 to 870 nm wavelengths. These features are apparently regional characteristics of the site. Aerosol asymmetry factor (AS) decreases gradually from 400 to 870 nm and varied from 0.66 to 0.69 at 500 nm across the seasons. Dominance of desert-dust aerosols, associated by coarse mode, is indicated by tri-modal features of aerosol volume size distribution over the station during the entire seasons.

  4. Numerical Simulation of Hurricane Bonnie (1998). Part II: Sensitivity to Varying Cloud Microphysical Processes.

    NASA Astrophysics Data System (ADS)

    Zhu, Tong; Zhang, Da-Lin

    2006-01-01

    In this study, the effects of various cloud microphysics processes on the hurricane intensity, precipitation, and inner-core structures are examined with a series of 5-day explicit simulations of Hurricane Bonnie (1998), using the results presented in Part I as a control run. It is found that varying cloud microphysics processes produces little sensitivity in hurricane track, except for very weak and shallow storms, but it produces pronounced departures in hurricane intensity and inner-core structures.Specifically, removing ice microphysics produces the weakest (15-hPa underdeepening) and shallowest storm with widespread cloud water but little rainwater in the upper troposphere. Removing graupel from the control run generates a weaker hurricane with a wider area of precipitation and more cloud coverage in the eyewall due to the enhanced horizontal advection of hydrometeors relative to the vertical fallouts (or increased water loading). Turning off the evaporation of cloud water and rainwater leads to the most rapid deepening storm (i.e., 90 hPa in 48 h) with the smallest radius but a wider eyewall and the strongest eyewall updrafts. The second strongest storm, but with the most amount of rainfall, is obtained when the melting effect is ignored. It is found that the cooling due to melting is more pronounced in the eyewall where more frozen hydrometeors, especially graupel, are available, whereas the evaporative cooling occurs more markedly when the storm environment is more unsaturated.It is shown that stronger storms tend to show more compact eyewalls with heavier precipitation and more symmetric structures in the warm-cored eye and in the eyewall. It is also shown that although the eyewall replacement scenarios occur as the simulated storms move into weak-sheared environments, the associated inner-core structural changes, timing, and location differ markedly, depending on the hurricane intensity. That is, the eyewall convection in weak storms tends to diminish

  5. The Role of Aerosols on Precipitation Processes: Cloud Resolving Model Simulations

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Li, X.; Matsui, T.

    2012-01-01

    Cloud microphysics is inevitably affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds. Therefore, size distributions parameterized as spectral bin microphysics are needed to explicitly study the effects of atmospheric aerosol concentration on cloud development, rainfall production, and rainfall rates for convective clouds. Recently, a detailed spectral-bin microphysical scheme was implemented into the Goddard Cumulus Ensemble (GCE) model. The formulation for the explicit spectral bin microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles [i.e. pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), graupel and frozen drops/hail]. Each type is described by a special size distribution function containing many categories (i.e., 33 bins). Atmospheric aerosols are also described using number density size-distribution functions. The model is tested by studying the evolution of deep cloud systems in the west Pacific warm pool region, the sub-tropics (Florida) and midlatitudes using identical thermodynamic conditions but with different concentrations of CCN: a low "clean" concentration and a high "dirty" concentration. Results indicate that the low CCN concentration case produces rainfall at the surface sooner than the high CeN case but has less cloud water mass aloft. Because the spectral-bin model explicitly calculates and allows for the examination of both the mass and number concentration of species in each size category, a detailed analysis of the instantaneous size spectrum can be obtained for these cases. It is shown that since the low (CN case produces fewer droplets, larger sizes develop due to greater condensational and collection growth, leading to a broader size spectrum in comparison to the high CCN case. Sensitivity tests were performed to

  6. Final Technical Report for Interagency Agreement No. DE-SC0005453 “Characterizing Aerosol Distributions, Types, and Optical and Microphysical Properties using the NASA Airborne High Spectral Resolution Lidar (HSRL) and the Research Scanning Polarimeter (RSP)”

    SciTech Connect

    Hostetler, Chris; Ferrare, Richard

    2015-01-13

    Measurements of the vertical profile of atmospheric aerosols and aerosol optical and microphysical characteristics are required to: 1) determine aerosol direct and indirect radiative forcing, 2) compute radiative flux and heating rate profiles, 3) assess model simulations of aerosol distributions and types, and 4) establish the ability of surface and space-based remote sensors to measure the indirect effect. Consequently the ASR program calls for a combination of remote sensing and in situ measurements to determine aerosol properties and aerosol influences on clouds and radiation. As part of our previous DOE ASP project, we deployed the NASA Langley airborne High Spectral Resolution Lidar (HSRL) on the NASA B200 King Air aircraft during major field experiments in 2006 (MILAGRO and MaxTEX), 2007 (CHAPS), 2009 (RACORO), and 2010 (CalNex and CARES). The HSRL provided measurements of aerosol extinction (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm). These measurements were typically made in close temporal and spatial coincidence with measurements made from DOE-funded and other participating aircraft and ground sites. On the RACORO, CARES, and CalNEX missions, we also deployed the NASA Goddard Institute for Space Studies (GISS) Research Scanning Polarimeter (RSP). RSP provided intensity and degree of linear polarization over a broad spectral and angular range enabling column-average retrievals of aerosol optical and microphysical properties. Under this project, we analyzed observations and model results from RACORO, CARES, and CalNex and accomplished the following objectives. 1. Identified aerosol types, characterize the vertical distribution of the aerosol types, and partition aerosol optical depth by type, for CARES and CalNex using HSRL data as we have done for previous missions. 2. Investigated aerosol microphysical and macrophysical properties using the RSP. 3. Used the aerosol backscatter and extinction profiles measured by the HSRL

  7. New, Improved Bulk-microphysical Schemes for Studying Precipitation Processes in WRF. Part 1; Comparisons with Other Schemes

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Shi, J.; Chen, S. S> ; Lang, S.; Hong, S.-Y.; Thompson, G.; Peters-Lidard, C.; Hou, A.; Braun, S.; Simpson, J.

    2007-01-01

    Advances in computing power allow atmospheric prediction models to be mn at progressively finer scales of resolution, using increasingly more sophisticated physical parameterizations and numerical methods. The representation of cloud microphysical processes is a key component of these models, over the past decade both research and operational numerical weather prediction models have started using more complex microphysical schemes that were originally developed for high-resolution cloud-resolving models (CRMs). A recent report to the United States Weather Research Program (USWRP) Science Steering Committee specifically calls for the replacement of implicit cumulus parameterization schemes with explicit bulk schemes in numerical weather prediction (NWP) as part of a community effort to improve quantitative precipitation forecasts (QPF). An improved Goddard bulk microphysical parameterization is implemented into a state-of the-art of next generation of Weather Research and Forecasting (WRF) model. High-resolution model simulations are conducted to examine the impact of microphysical schemes on two different weather events (a midlatitude linear convective system and an Atllan"ic hurricane). The results suggest that microphysics has a major impact on the organization and precipitation processes associated with a summer midlatitude convective line system. The 31CE scheme with a cloud ice-snow-hail configuration led to a better agreement with observation in terms of simulated narrow convective line and rainfall intensity. This is because the 3ICE-hail scheme includes dense ice precipitating (hail) particle with very fast fall speed (over 10 m/s). For an Atlantic hurricane case, varying the microphysical schemes had no significant impact on the track forecast but did affect the intensity (important for air-sea interaction)

  8. Anvil Glaciation in a Deep Cumulus Updraught over Florida Simulated with the Explicit Microphysics Model. I: Impact of Various Nucleation Processes

    NASA Technical Reports Server (NTRS)

    Phillips, Vaughan T. J.; Andronache, Constantin; Sherwood, Steven C.; Bansemer, Aaron; Conant, William C.; Demott, Paul J.; Flagan, Richard C.; Heymsfield, Andy; Jonsson, Haflidi; Poellot, Micheal; Rissman, Tracey A.; Seinfeld, John H.; Vanreken, Tim; Varutbangkul, Varuntida; Wilson, James C.

    2005-01-01

    Simulations of a cumulonimbus cloud observed in the Cirrus regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) with an advanced version of the Explicit Microphysics Model (EMM) are presented. The EMM has size-resolved aerosols and predicts the time evolution of sizes, bulk densities and axial ratios of ice particles. Observations by multiple aircraft in the troposphere provide inputs to the model, including observations of the ice nuclei and of the entire size distribution of condensation nuclei. Homogeneous droplet freezing is found to be the source of almost all of the ice crystals in the anvil updraught of this particular model cloud. Most of the simulated droplets that freeze to form anvil crystals appear to be nucleated by activation of aerosols far above cloud base in the interior of the cloud ("secondary" or "in cloud" droplet nucleation). This is partly because primary droplets formed at cloud base are invariably depleted by accretion before they can reach the anvil base in the updraught, which promotes an increase with height of the average supersaturation in the updraught aloft. More than half of these aerosols, activated far above cloud base, are entrained into the updraught of this model cloud from the lateral environment above about 5 km above mean sea level. This confirms the importance of remote sources of atmospheric aerosol for anvil glaciation. Other nucleation processes impinge indirectly upon the anvil glaciation by modifying the concentration of supercooled droplets in the upper levels of the mixed-phase region. For instance, the warm-rain process produces a massive indirect impact on the anvil crystal concentration, because it determines the mass of precipitation forming in the updraught. It competes with homogeneous freezing as a sink for cloud droplets. The effects from turbulent enhancement of the warm-rain process and from the nucleation processes on the anvil ice properties are assessed.

  9. Laboratory Investigation of Contact Freezing and the Aerosol to Ice Crystal Transformation Process

    SciTech Connect

    Shaw, Raymond A.

    2014-10-28

    This project has been focused on the following objectives: 1. Investigations of the physical processes governing immersion versus contact nucleation, specifically surface-induced crystallization; 2. Development of a quadrupole particle trap with full thermodynamic control over the temperature range 0 to –40 °C and precisely controlled water vapor saturation ratios for continuous, single-particle measurement of the aerosol to ice crystal transformation process for realistic ice nuclei; 3. Understanding the role of ice nucleation in determining the microphysical properties of mixed-phase clouds, within a framework that allows bridging between laboratory and field measurements.

  10. Evidence of Mineral Dust Altering Cloud Microphysics and Precipitation

    NASA Technical Reports Server (NTRS)

    Min, Qilong; Li, Rui; Lin, Bing; Joseph, Everette; Wang, Shuyu; Hu, Yongxiang; Morris, Vernon; Chang, F.

    2008-01-01

    Multi-platform and multi-sensor observations are employed to investigate the impact of mineral dust on cloud microphysical and precipitation processes in mesoscale convective systems. It is clearly evident that for a given convection strength,small hydrometeors were more prevalent in the stratiform rain regions with dust than in those regions that were dust free. Evidence of abundant cloud ice particles in the dust sector, particularly at altitudes where heterogeneous nucleation process of mineral dust prevails, further supports the observed changes of precipitation. The consequences of the microphysical effects of the dust aerosols were to shift the precipitation size spectrum from heavy precipitation to light precipitation and ultimately suppressing precipitation.

  11. Consistency among microphysics-convection-radiation processes in a numerical forecasting model

    NASA Astrophysics Data System (ADS)

    Bae, Soo Ya; Park, Raeseol; Hong, Song-You

    2016-04-01

    Radiative fluxes are mainly affected by the cloud optical properties calculated with effective radius, water path of hydrometeors, and cloud fraction. A prognostic cloud fraction scheme, which considers the cloud fraction with increments as a result of each physics process, is implemented in the Global/Regional Integrated Model system (GRIMs) (Park et al., 2016). However, the original RRTMG scheme does not consider the hydrometeor information from convection processes, resulting in inconsistency between cloud process and radiation activity. To ensure consistency among physics processes, the amount of hydrometeors from both the cumulus parameterization scheme (CPS) and microphysics schemes is explicitly taken into account in computing radiative fluxes. The effects of this modification are tested for a heavy rainfall over Korea to identify the feedback between the precipitation and radiation processes. It is found that the information of hydrometeors from CPS tends to increase water path, which leads to larger cloud optical depth and cooling. Skill scores of the simulated precipitation in a medium-range forecast testbed confirm benefits of the consistent treatment of hydrometeors in both CPS and radiation processes.

  12. Microphysics of Amazonian aerosol under background conditions and the impact from the urban pollution and biomass burning

    NASA Astrophysics Data System (ADS)

    Wang, J.; Alexander, M. L. L.; Andreae, M. O.; Artaxo, P.; Barbosa, H. M.; Brito, J.; Campuzano Jost, P.; Comstock, J. M.; Day, D. A.; de Sá, S. S.; Giangrande, S. E.; Manninen, H. E.; Hu, W.; Jefferson, A.; Jimenez, J. L.; Krejci, R.; Pöhlker, M. L.; Kuang, C.; Kulmala, M. T.; Lavric, J.; Machado, L.; Martin, S. T.; Mei, F.; Palm, B. B.; Petäjä, T.; Pöhlker, C.; Schmid, B.; Sedlacek, A. J., III; Shilling, J. E.; Smith, J. N.; Souza, R. A. F. D.; Springston, S. R.; Thalman, R.; Tomlinson, J. M.; Toto, T.; Walter, D.; Wimmer, D.

    2015-12-01

    The Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) campaign took place from January 2014 to December 2015 in the vicinity of Manaus, Brazil. One main objective of GoAmazon 2014/5 is to investigate the aerosol lifecycle under background conditions and the impact from the Manaus pollution plume and biomass burning. Here we present the diurnal variation of aerosol properties, including aerosol size distribution and CCN spectrum, observed at the T0a background site (Amazon Tall Tower Observatory, 150 km upwind of Manaus) and the T3 site (70 km downwind of Manaus). Also shown are vertical distributions of aerosol observed onboard the DOE Gulfstream-1 research aircraft. During the wet season, aerosol under background conditions often exhibited a bimodal size distribution with an average concentration of ~320 cm-3. The vertical profile of aerosol size distribution showed high concentrations of Aitken mode particles in the free troposphere, suggesting particle sources at high altitudes. The sources and sinks of the boundary layer aerosol particles under the wet season background conditions are examined. During the dry season, background aerosol concentration increased by a factor of ~5 to ~1500 cm-3, due to a combination of regional biomass burning emissions and other factors. Background aerosol size distribution was typically unimodal with the mode diameter between 100 and 200 nm. Nucleation and Aiken mode particle concentrations exhibited strong enhancements in the Manaus plume. As the plume traveled downwind, particle growth and higher CCN activation fraction were observed, and are attributed to condensation of secondary species and coagulation. The impact of the Manaus urban plume on aerosol size distribution, CCN spectrum, and optical properties are examined, and the results from wet and dry seasons are compared.

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

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Khain, A.; Simpson, S.; Johnson, D.; Li, X.; Remer, L.

    2003-01-01

    Cloud microphysics are inevitable affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds. Therefore, size distribution parameterized as spectral bin microphysics are needed to explicitly study the effect of atmospheric aerosol concentration on cloud development, rainfall production, and rainfall rates convective clouds. Recently, two detailed spectral-bin microphysical schemes were implemented into the Goddard Cumulus Ensembel (GCE) model. The formulation for the explicit spectral-bim microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles [i.e., pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), groupel and frozen drops/hall] Each type is described by a special size distribution function containing many categories (i.e., 33 bins). Atmospheric aerosols are also described using number density size-distribution functions.A spectral-bin microphysical model is very expensive from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep cloud systems in the west Pacific warm pool region and in the mid-latitude using identical thermodynamic conditions but with different concentrations of CCN: a low "clean" concentration and a high "dirty" concentration. Besides the initial differences in aerosol concentration, preliminary results indicate that the low CCN concentration case produces rainfall at the surface sooner than the high CCN case but has less cloud water mass aloft. Because the spectral-bim model explicitly calculates and allows for the examination of both the mass and number concentration of cpecies in each size category, a detailed analysis of the instantaneous size spectrum can be obtained for the two cases. It is shown that since the low

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

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Khain, A.; Simpson, S.; Johnson, D.; Li, X.; Remer, L.

    2003-01-01

    Cloud microphysics are inevitably affected by the smoke particle (CCN, cloud condensation nuclei) size distributions below the clouds. Therefore, size distributions parameterized as spectral bin microphysics are needed to explicitly study the effects of atmospheric aerosol concentration on cloud development, rainfall production, and rainfall rates for convective clouds. Recently, two detailed spectral-bin microphysical schemes were implemented into the Goddard Cumulus Ensemble (GCE) model. The formulation for the explicit spectral-bin microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (i.e., cloud droplets and raindrops), and several types of ice particles [i.e.,pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), graupel and frozen drops/hail]. Each type is described by a special size distribution function containing many categories (i.e. 33 bins). Atmospheric aerosols are also described using number density size-distribution functions.A spectral-bin microphysical model is very expensive from a from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep tropical clouds in the west Pacific warm pool region using identical thermodynamic conditions but with different concentrations of CCN: a low "clean" concentration and a high "dirty" concentration. Besides the initial differences in aerosol concentration, preliminary results indicate that the low CCN concentration case produces rainfall at the surface sooner than the high CCN case but has less cloud water mass aloft. Because the spectral-bin model explicitly calculates and allows for the examination of both the mass and number concentration of species in each size categor, a detailed analysis of the instantaneous size spectrum can be obtained for the two cases. It is shown that since the low CCN case

  15. Light absorption, optical and microphysical properties of trajectory-clustered aerosols at two AERONET sites in West Africa

    NASA Astrophysics Data System (ADS)

    Fawole, O. G.; Cai, X.; MacKenzie, A. R.

    2015-12-01

    Aerosol remote sensing techniques and back-trajectory modeling can be combined to identify aerosol types. We have clustered 7 years of AERONET aerosol signals using trajectory analysis to identify dominant aerosol sources at two AERONET sites in West Africa: Ilorin (4.34 oE, 8.32 oN) and Djougou (1.60 oE, 9.76 oN). Of particular interest are air masses that have passed through the gas flaring region in the Niger Delta area, of Nigeria, en-route the AERONET sites. 7-day back trajectories were calculated using the UK UGAMP trajectory model driven by ECMWF wind analyses data. Dominant sources identified, using literature classifications, are desert dust (DD), Biomass burning (BB) and Urban-Industrial (UI). Below, we use a combination of synoptic trajectories and aerosol optical properties to distinguish a fourth source: that due to gas flaring. Gas flaring, (GF) the disposal of gas through stack in an open-air flame, is believed to be a prominent source of black carbon (BC) and greenhouse gases. For these different aerosol source signatures, single scattering albedo (SSA), refractive index , extinction Angstrom exponent (EEA) and absorption Angstrom exponent (AAE) were used to classify the light absorption characteristics of the aerosols for λ = 440, 675, 870 and1020 nm. A total of 1625 daily averages of aerosol data were collected for the two sites. Of which 245 make up the GF cluster for both sites. For GF cluster, the range of fine-mode fraction is 0.4 - 0.7. Average values SSA(λ), for the total and GF clusters are 0.90(440), 0.93(675), 0.95(870) and 0.96(1020), and 0.93(440), 0.92(675), 0.9(870) and 0.9(1020), respectively. Values of for the GF clusters for both sites are 0.62 - 1.11, compared to 1.28 - 1.66 for the remainder of the clusters, which strongly indicates the dominance of carbonaceous particles (BC), typical of a highly industrial area. An average value of 1.58 for the real part of the refractive index at low SSA for aerosol in the GF cluster is also

  16. Aerosol and cloud microphysics covariability in the northeast Pacific boundary layer estimated with ship-based and satellite remote sensing observations

    NASA Astrophysics Data System (ADS)

    Painemal, David; Chiu, J.-Y. Christine; Minnis, Patrick; Yost, Christopher; Zhou, Xiaoli; Cadeddu, Maria; Eloranta, Edwin; Lewis, Ernie R.; Ferrare, Richard; Kollias, Pavlos

    2017-02-01

    Ship measurements collected over the northeast Pacific along transects between the port of Los Angeles (33.7°N, 118.2°W) and Honolulu (21.3°N, 157.8°W) during May to August 2013 were utilized to investigate the covariability between marine low cloud microphysical and aerosol properties. Ship-based retrievals of cloud optical depth (τ) from a Sun photometer and liquid water path (LWP) from a microwave radiometer were combined to derive cloud droplet number concentration Nd and compute a cloud-aerosol interaction (ACI) metric defined as ACICCN = ∂ ln(Nd)/∂ ln(CCN), with CCN denoting the cloud condensation nuclei concentration measured at 0.4% (CCN0.4) and 0.3% (CCN0.3) supersaturation. Analysis of CCN0.4, accumulation mode aerosol concentration (Na), and extinction coefficient (σext) indicates that Na and σext can be used as CCN0.4 proxies for estimating ACI. ACICCN derived from 10 min averaged Nd and CCN0.4 and CCN0.3, and CCN0.4 regressions using Na and σext, produce high ACICCN: near 1.0, that is, a fractional change in aerosols is associated with an equivalent fractional change in Nd. ACICCN computed in deep boundary layers was small (ACICCN = 0.60), indicating that surface aerosol measurements inadequately represent the aerosol variability below clouds. Satellite cloud retrievals from MODerate-resolution Imaging Spectroradiometer and GOES-15 data were compared against ship-based retrievals and further analyzed to compute a satellite-based ACICCN. Satellite data correlated well with their ship-based counterparts with linear correlation coefficients equal to or greater than 0.78. Combined satellite Nd and ship-based CCN0.4 and Na yielded a maximum ACICCN = 0.88-0.92, a value slightly less than the ship-based ACICCN, but still consistent with aircraft-based studies in the eastern Pacific.

  17. Effects of microphysics and radiation on mesoscale processes of a midlatitude squall line

    SciTech Connect

    Chin, Hung-Neng Steve

    1994-04-01

    The understanding of the essential dynamics of mesoscale convective systems (MCSs) was well addressed in the literature. Effects of different physics on mesoscale processes of MCSs are, however, not well understood at some particular aspects, such as the origins of the rear inflow and the transition zone in the radar reflectivity. The objective of this research is focused on these two aspects for a midlatitude broken-line squall system. The existence of the rear inflow in MCSs has been identified in many observational and modeling studies. Although convincing evidence has shown that physical internal to the mesoscale system and pressure gradient effects in the convective and trailing stratiform regions are undoubtedly important in developing the rear inflow, it remains unclear bow these internal processes interact with pressure effects to trigger the rear inflow. Moreover, many modeling studies have replicated the bright melting ban, but the transition zone has not been successfully simulated. With the enhanced model physics, such as radiation, in a cloud model, we can simulate these features and provide some supplemental evidences, at least in part, to explain them. The modulation of the rear inflow by microphysics, long- (LW) and shortwave (SW) radiation, and its related cloud-radiative feedback to the modeled squall line system are also discussed in this study.

  18. Aeronet-based Microphysical and Optical Properties of Smoke-dominated Aerosol near Source Regions and Transported over Oceans, and Implications for Satellite Retrievals of Aerosol Optical Depth

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    Smoke aerosols from biomass burning are an important component of the global aerosol cycle. Analysis of Aerosol Robotic Network (AERONET) retrievals of size distribution and refractive index reveals variety between biomass burning aerosols in different global source regions, in terms of aerosol particle size and single scatter albedo (SSA). Case studies of smoke transported to coastal/island AERONET sites also mostly lie within the range of variability at near-source sites. Two broad families of aerosol properties are found, corresponding to sites dominated by boreal forest burning (larger, broader fine mode, with midvisible SSA 0.95), and those influenced by grass, shrub, or crop burning with additional forest contributions (smaller, narrower particles with SSA 0.88-0.9 in the midvisible). The strongest absorption is seen in southern African savanna at Mongu (Zambia), with average SSA 0.85 in the midvisible. These can serve as candidate sets of aerosol microphysicaloptical properties for use in satellite aerosol optical depth (AOD) retrieval algorithms. The models presently adopted by these algorithms over ocean are often insufficiently absorbing to represent these biomass burning aerosols. A corollary of this is an underestimate of AOD in smoke outflow regions, which has important consequences for applications of these satellite datasets.

  19. A Comparison between Airborne and Mountaintop Cloud Microphysics

    NASA Astrophysics Data System (ADS)

    David, R.; Lowenthal, D. H.; Hallar, A. G.; McCubbin, I.; Avallone, L. M.; Mace, G. G.; Wang, Z.

    2014-12-01

    Complex terrain has a large impact on cloud dynamics and microphysics. Several studies have examined the microphysical details of orographically-enhanced clouds from either an aircraft or from a mountain top location. However, further research is needed to characterize the relationships between mountain top and airborne microphysical properties. During the winter of 2011, an airborne study, the Colorado Airborne Mixed-Phase Cloud Study (CAMPS), and a ground-based field campaign, the Storm Peak Lab (SPL) Cloud Property Validation Experiment (StormVEx) were conducted in the Park Range of the Colorado Rockies. The CAMPS study utilized the University of Wyoming King Air (UWKA) to provide airborne cloud microphysical and meteorological data on 29 flights totaling 98 flight hours over the Park Range from December 15, 2010 to February 28, 2011. The UWKA was equipped with instruments that measured both cloud droplet and ice crystal size distributions, liquid water content, total water content (vapor, liquid, and ice), and 3-dimensional wind speed and direction. The Wyoming Cloud Radar and Lidar were also deployed during the campaign. These measurements are used to characterize cloud structure upwind and above the Park Range. StormVEx measured cloud droplet, ice crystal, and aerosol size distributions at SPL, located on the west summit of Mt. Werner at 3220m MSL. The observations from SPL are used to determine mountain top cloud microphysical properties at elevations lower than the UWKA was able to sample in-situ. Comparisons showed that cloud microphysics aloft and at the surface were consistent with respect to snow growth processes while small crystal concentrations were routinely higher at the surface, suggesting ice nucleation near cloud base. The effects of aerosol concentrations and upwind stability on mountain top and downwind microphysics are considered.

  20. Dominant cloud microphysical processes of a torrential rainfall event in Sichuan, China

    NASA Astrophysics Data System (ADS)

    Huang, Yongjie; Cui, Xiaopeng

    2015-03-01

    High-resolution numerical simulation data of a rainstorm triggering debris flow in Sichuan Province of China simulated by the Weather Research and Forecasting (WRF) Model were used to study the dominant cloud microphysical processes of the torrential rainfall. The results showed that: (1) In the strong precipitation period, particle sizes of all hydrometeors increased, and mean-mass diameters of graupel increased the most significantly, as compared with those in the weak precipitation period; (2) The terminal velocity of raindrops was the strongest among all hydrometeors, followed by graupel's, which was much smaller than that of raindrops. Differences between various hydrometeors' terminal velocities in the strong precipitation period were larger than those in the weak precipitation period, which favored relative motion, collection interaction and transformation between the particles. Absolute terminal velocity values of raindrops and graupel were significantly greater than those of air upward velocity, and the stronger the precipitation was, the greater the differences between them were; (3) The orders of magnitudes of the various hydrometeors' sources and sinks in the strong precipitation period were larger than those in the weak precipitation period, causing a difference in the intensity of precipitation. Water vapor, cloud water, raindrops, graupel and their exchange processes played a major role in the production of the torrential rainfall, and there were two main processes via which raindrops were generated: abundant water vapor condensed into cloud water and, on the one hand, accretion of cloud water by rain water formed rain water, while on the other hand, accretion of cloud water by graupel formed graupel, and then the melting of graupel formed rain water.

  1. 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

  2. Putting the clouds back in aerosol-cloud interactions

    NASA Astrophysics Data System (ADS)

    Gettelman, A.

    2015-11-01

    Aerosol-cloud interactions (ACI) are the consequence of perturbed aerosols affecting cloud drop and crystal number, with corresponding microphysical and radiative effects. ACI are sensitive to both cloud microphysical processes (the "C" in ACI) and aerosol emissions and processes (the "A" in ACI). This work highlights the importance of cloud microphysical processes, using idealized and global tests of a cloud microphysics scheme used for global climate prediction. Uncertainties in key cloud microphysical processes examined with sensitivity tests cause uncertainties of nearly -30 to +60 % in ACI, similar to or stronger than uncertainties identified due to natural aerosol emissions (-30 to +30 %). The different dimensions and sensitivities of ACI to microphysical processes identified in previous work are analyzed in detail, showing that precipitation processes are critical for understanding ACI and that uncertain cloud lifetime effects are nearly one-third of simulated ACI. Buffering of different processes is important, as is the mixed phase and coupling of the microphysics to the condensation and turbulence schemes in the model.

  3. Effects of Cloud-Microphysics on Tropical Atmospheric Hydrologic Processes in the GEOS GCM

    NASA Technical Reports Server (NTRS)

    Lau, K. M.; Wu, H. T.; Sud, Y. C.; Walker, G. K.

    2004-01-01

    The sensitivity of tropical atmospheric hydrologic processes to cloud-microphysics is investigated using the NASA GEOS GCM. Results show that a faster autoconversion - rate produces more warm rain and less clouds at all levels. Fewer clouds enhances longwave cooling and reduces shortwave heating in the upper troposphere, while more warm rain produces increased condensation heating in the lower troposphere. This vertical heating differential destablizes the tropical atmosphere, producing a positive feedback resulting in more rain over the tropics. The feedback is maintained via a two-cell secondary circulation. The lower cell is capped by horizontal divergence and maximum cloud detrainment near the melting/freezing, with rising motion in the warm rain region connected to descending motion in the cold rain region. The upper cell is found above the freezing/melting level, with longwave-induced subsidence in the warm rain and dry regions, coupled to forced ascent in the deep convection region. The tropical large scale circulation is found to be very sensitive to the radiative-dynamic effects induced by changes in autoconversion rate. Reduced cloud-radiation processes feedback due to a faster autoconversion rate results in intermittent but more energetic eastward propagating Madden and Julian Oscillations (MJO). Conversely,-a slower autconversion rate, with increased cloud radiation produces MJO's with more realistic westward propagating transients, resembling a supercloud cluster structure. Results suggests that warm rain and associated low and mid level clouds, i.e., cumulus congestus, may play a critical role in regulating the time-intervals of deep convections and hence the fundamental time scales of the MJO.

  4. ISDAC Microphysics

    DOE Data Explorer

    McFarquhar, Greg

    2011-07-25

    Best estimate of cloud microphysical parameters derived using data collected by the cloud microphysical probes installed on the National Research Council (NRC) of Canada Convair-580 during ISDAC. These files contain phase, liquid and ice crystal size distributions (Nw(D) and Ni(D) respectively), liquid water content (LWC), ice water content (IWC), extinction of liquid drops (bw), extinction of ice crystals (bi), effective radius of water drops (rew) and of ice crystals (rei) and median mass diameter of liquid drops (Dmml) and of ice crystals (Dmmi) at 30 second resolution.

  5. A key process controlling the wet removal of aerosols: new observational evidence

    NASA Astrophysics Data System (ADS)

    Ohata, Sho; Moteki, Nobuhiro; Mori, Tatsuhiro; Koike, Makoto; Kondo, Yutaka

    2016-10-01

    The lifetime and spatial distributions of accumulation-mode aerosols in a size range of approximately 0.05–1 μm, and thus their global and regional climate impacts, are primarily constrained by their removal via cloud and precipitation (wet removal). However, the microphysical process that predominantly controls the removal efficiency remains unidentified because of observational difficulties. Here, we demonstrate that the activation of aerosols to cloud droplets (nucleation scavenging) predominantly controls the wet removal efficiency of accumulation-mode aerosols, using water-insoluble black carbon as an observable particle tracer during the removal process. From simultaneous ground-based observations of black carbon in air (prior to removal) and in rainwater (after removal) in Tokyo, Japan, we found that the wet removal efficiency depends strongly on particle size, and the size dependence can be explained quantitatively by the observed size-dependent cloud-nucleating ability. Furthermore, our observational method provides an estimate of the effective supersaturation of water vapour in precipitating cloud clusters, a key parameter controlling nucleation scavenging. These novel data firmly indicate the importance of quantitative numerical simulations of the nucleation scavenging process to improve the model’s ability to predict the atmospheric aerosol burden and the resultant climate forcings, and enable a new validation of such simulations.

  6. A key process controlling the wet removal of aerosols: new observational evidence

    PubMed Central

    Ohata, Sho; Moteki, Nobuhiro; Mori, Tatsuhiro; Koike, Makoto; Kondo, Yutaka

    2016-01-01

    The lifetime and spatial distributions of accumulation-mode aerosols in a size range of approximately 0.05–1 μm, and thus their global and regional climate impacts, are primarily constrained by their removal via cloud and precipitation (wet removal). However, the microphysical process that predominantly controls the removal efficiency remains unidentified because of observational difficulties. Here, we demonstrate that the activation of aerosols to cloud droplets (nucleation scavenging) predominantly controls the wet removal efficiency of accumulation-mode aerosols, using water-insoluble black carbon as an observable particle tracer during the removal process. From simultaneous ground-based observations of black carbon in air (prior to removal) and in rainwater (after removal) in Tokyo, Japan, we found that the wet removal efficiency depends strongly on particle size, and the size dependence can be explained quantitatively by the observed size-dependent cloud-nucleating ability. Furthermore, our observational method provides an estimate of the effective supersaturation of water vapour in precipitating cloud clusters, a key parameter controlling nucleation scavenging. These novel data firmly indicate the importance of quantitative numerical simulations of the nucleation scavenging process to improve the model’s ability to predict the atmospheric aerosol burden and the resultant climate forcings, and enable a new validation of such simulations. PMID:27703169

  7. 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.

  8. Brown carbon aerosols from burning of boreal peatlands: microphysical properties, emission factors, and implications for direct radiative forcing

    NASA Astrophysics Data System (ADS)

    Chakrabarty, Rajan K.; Gyawali, Madhu; Yatavelli, Reddy L. N.; Pandey, Apoorva; Watts, Adam C.; Knue, Joseph; Chen, Lung-Wen A.; Pattison, Robert R.; Tsibart, Anna; Samburova, Vera; Moosmüller, Hans

    2016-03-01

    The surface air warming over the Arctic has been almost twice as much as the global average in recent decades. In this region, unprecedented amounts of smoldering peat fires have been identified as a major emission source of climate-warming agents. While much is known about greenhouse gas emissions from these fires, there is a knowledge gap on the nature of particulate emissions and their potential role in atmospheric warming. Here, we show that aerosols emitted from burning of Alaskan and Siberian peatlands are predominantly brown carbon (BrC) - a class of visible light-absorbing organic carbon (OC) - with a negligible amount of black carbon content. The mean fuel-based emission factors for OC aerosols ranged from 3.8 to 16.6 g kg-1. Their mass absorption efficiencies were in the range of 0.2-0.8 m2 g-1 at 405 nm (violet) and dropped sharply to 0.03-0.07 m2 g-1 at 532 nm (green), characterized by a mean Ångström exponent of ≈ 9. Electron microscopy images of the particles revealed their morphologies to be either single sphere or agglomerated "tar balls". The shortwave top-of-atmosphere aerosol radiative forcing per unit optical depth under clear-sky conditions was estimated as a function of surface albedo. Only over bright surfaces with albedo greater than 0.6, such as snow cover and low-level clouds, the emitted aerosols could result in a net warming (positive forcing) of the atmosphere.

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

    SciTech Connect

    Rosenfeld, Daniel

    2015-12-23

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

  10. Sensitivity of Cloud Microphysics to Choice of Physics Parameterizations : a Crm Study

    NASA Astrophysics Data System (ADS)

    Sarangi, C.; Tripathi, S. N.

    2013-12-01

    Weather Research and Forecasting regional meteorological model coupled with chemistry (WRF-Chem) is being used widely to study direct and indirect effect of aerosols. The results of a numerical study on the impacts of aerosols on meteorology and microphysics depend on the accuracy with which the model parameterizes any weather conditions. This study investigates the sensitivity of simulated hydrometeors at 3 km resolution over Northern India, to different types of microphysics parameterizations, such as ETA microphysics (only warm rain processes are parameterized), LIN microphysics (single moment including ice processes) and Morrison microphysics (double moment including ice processes) and planetary boundary layer parameterizations (Yonsei and MYJ). WRF's ability to simulate the vertical and horizontal distribution of hydrometeors using cloud resolving mode is evaluated using in-situ aircraft measurements of hydrometeors during CAIPEEX campaign and cloud products from MODIS satellite. The results suggest that the model underestimates the mass concentration of hydrometeors, but can reasonably simulate the distribution of hydrometeors at most places, except a few places where the hydrometeors are modeled simulated at higher altitude than observed. Ongoing work includes aerosol impact on these simulated hydrometeors distribution.

  11. Evolution of biomass burning aerosol over the Amazon: airborne measurements of aerosol chemical composition, microphysical properties, mixing state and optical properties during SAMBBA

    NASA Astrophysics Data System (ADS)

    Morgan, W.; Allan, J. D.; Flynn, M.; Darbyshire, E.; Hodgson, A.; Liu, D.; O'Shea, S.; Bauguitte, S.; Szpek, K.; Johnson, B.; Haywood, J.; Longo, K.; Artaxo, P.; Coe, H.

    2013-12-01

    Biomass burning represents one of the largest sources of particulate matter to the atmosphere, resulting in a significant perturbation to the Earth's radiative balance coupled with serious impacts on public health. On regional scales, the impacts are substantial, particularly in areas such as the Amazon Basin where large, intense and frequent burning occurs on an annual basis for several months. Absorption by atmospheric aerosols is underestimated by models over South America, which points to significant uncertainties relating to Black Carbon (BC) aerosol properties. Initial results from the South American Biomass Burning Analysis (SAMBBA) field experiment, which took place during September and October 2012 over Brazil on-board the UK Facility for Airborne Atmospheric Measurement (FAAM) BAe-146 research aircraft, are presented here. Aerosol chemical composition was measured by an Aerodyne Aerosol Mass Spectrometer (AMS) and a DMT Single Particle Soot Photometer (SP2). The physical, chemical and optical properties of the aerosols across the region will be characterized in order to establish the impact of biomass burning on regional air quality, weather and climate. The aircraft sampled a range of conditions including sampling of pristine Rainforest, fresh biomass burning plumes, regional haze and elevated biomass burning layers within the free troposphere. The aircraft sampled biomass burning aerosol across the southern Amazon in the states of Rondonia and Mato Grosso, as well as in a Cerrado (Savannah-like) region in Tocantins state. This presented a range of fire conditions, in terms of their number, intensity, vegetation-type and their combustion efficiencies. Near-source sampling of fires in Rainforest environments suggested that smouldering combustion dominated, while flaming combustion dominated in the Cerrado. This led to significant differences in aerosol chemical composition, particularly in terms of the BC content, with BC being enhanced in the Cerrado

  12. A Cloud-Resolving Modeling Intercomparison Study on Properties of Cloud Microphysics, Convection, and Precipitation for a Squall Line Cas

    NASA Astrophysics Data System (ADS)

    Fan, J.; Han, B.; Morrison, H.; Varble, A.; Mansell, E.; Milbrandt, J.; Wang, Y.; Lin, Y.; Dong, X.; Giangrande, S. E.; Jensen, M. P.; Collis, S. M.; North, K.; Kollias, P.

    2015-12-01

    The large spread in CRM model simulations of deep convection and aerosol effects on deep convective clouds (DCCs) makes it difficult (1) to further our understanding of deep convection and (2) to define "benchmarks" and recommendations for their use in parameterization developments. Past model intercomparison studies used different models with different complexities of dynamic-microphysics interactions, making it hard to isolate the causes of differences between simulations. In this intercomparison study, we employed a much more constrained approach - with the same model and same experiment setups for simulations with different cloud microphysics schemes (one-moment, two-moment, and bin models). Both the piggybacking and interactive approaches are employed to explore the major microphysical processes that control the model differences and the significance of their feedback to dynamics through latent heating/cooling and cold pool characteristics. Real-case simulations are conducted for the squall line case 20 May 2011 from the MC3E field campaign. Results from the piggybacking approach show substantially different responses of the microphysics schemes to the same dynamical fields. Although the interactive microphysics-dynamics simulations buffer some differences compared with those from the piggyback runs, large differences still exist and are mainly contributed by ice microphysical processes parameterizations. The presentation will include in-depth analyses of the major microphysical processes for the squall line case, the significance of the feedback of the processes to dynamics, and how those results differ in different cloud microphysics schemes.

  13. Evaluation of Microphysics Parameterization for Convective Clouds in the NCAR Community Atmosphere Model CAM5

    NASA Astrophysics Data System (ADS)

    Song, X.; Zhang, G. J.; Li, J. F.

    2012-12-01

    A physically-based two-moment microphysics parameterization scheme for convective clouds is implemented in the NCAR CAM5 to improve the representation of convective clouds and their interaction with large-scale clouds and aerosols. The explicit treatment of mass mixing ratio and number concentration of cloud and precipitation particles enables the scheme to account for the impact of aerosols on convection. The scheme is linked to aerosols through cloud droplet activation and ice nucleation processes, and to stratiform cloud parameterization through convective detrainment of cloud liquid/ice water content (LWC/IWC) and droplet/crystal number concentration (DNC/CNC). A 5-yr simulation with the new convective microphysics scheme shows that both cloud LWC/IWC and DNC/CNC are in good agreement with observations, indicating the scheme describes microphysical processes in convection well. Moreover, the microphysics scheme is able to represent the aerosol effects on convective clouds such as the suppression of warm rain formation and enhancement of freezing when aerosol loading is increased. With more realistic simulations of convective cloud microphysical properties and their detrainment, the mid- and low-level cloud fraction is increased significantly over the ITCZ/SPCZ and subtropical oceans, making it much closer to the observations. Correspondingly the serious negative bias in cloud liquid water path over subtropical oceans observed in the standard CAM5 is reduced markedly. The large-scale precipitation is increased and precipitation distribution is improved as well. The longstanding precipitation bias in the western Pacific is significantly alleviated due to microphysics-thermodynamics-circulation feedbacks.

  14. Stratospheric Heterogeneous Chemistry and Microphysics: Model Development, Validation and Applications

    NASA Technical Reports Server (NTRS)

    Turco, Richard P.

    1996-01-01

    The objectives of this project are to: define the chemical and physical processes leading to stratospheric ozone change that involve polar stratospheric clouds (PSCS) and the reactions occurring on the surfaces of PSC particles; study the formation processes, and the physical and chemical properties of PSCS, that are relevant to atmospheric chemistry and to the interpretation of field measurements taken during polar stratosphere missions; develop quantitative models describing PSC microphysics and heterogeneous chemical processes; assimilate laboratory and field data into these models; and calculate the extent of chemical processing on PSCs and the impact of specific microphysical processes on polar composition and ozone depletion. During the course of the project, a new coupled microphysics/physical-chemistry/ photochemistry model for stratospheric sulfate aerosols and nitric acid and ice PSCs was developed and applied to analyze data collected during NASA's Arctic Airborne Stratospheric Expedition-II (AASE-II) and other missions. In this model, detailed treatments of multicomponent sulfate aerosol physical chemistry, sulfate aerosol microphysics, polar stratospheric cloud microphysics, PSC ice surface chemistry, as well as homogeneous gas-phase chemistry were included for the first time. In recent studies focusing on AASE measurements, the PSC model was used to analyze specific measurements from an aircraft deployment of an aerosol impactor, FSSP, and NO(y) detector. The calculated results are in excellent agreement with observations for particle volumes as well as NO(y) concentrations, thus confirming the importance of supercooled sulfate/nitrate droplets in PSC formation. The same model has been applied to perform a statistical study of PSC properties in the Northern Hemisphere using several hundred high-latitude air parcel trajectories obtained from Goddard. The rates of ozone depletion along trajectories with different meteorological histories are presently

  15. Processes Controlling the Seasonal Cycle of Arctic Aerosol Number and Size Distributions

    NASA Astrophysics Data System (ADS)

    Wentworth, G.; Croft, B.; Martin, R.; Leaitch, W. R.; Tunved, P.; Breider, T. J.; D'Andrea, S.; Pierce, J. R.; Murphy, J. G.; Kodros, J.; Abbatt, J.

    2015-12-01

    Measurements at high-Arctic sites show a strong seasonal cycle in aerosol number and size. The number of aerosols with diameters larger than 20 nm exhibits a maximum in late spring associated with a dominant accumulation mode, and a second maximum in the summer associated with a dominant Aitken mode. Seasonal-mean aerosol effective diameter ranges from about 160 nm in summer to 250 nm in winter. This study interprets these seasonal cycles with the GEOS-Chem-TOMAS global aerosol microphysics model. We find improved agreement with in situ measurements (SMPS) of aerosol size at both Alert, Nunavut, and Mt. Zeppelin, Svalbard following model developments: 1) increase the efficiency of wet scavenging in the Arctic summer and 2) represent coagulation between interstitial aerosols and aerosols activated to form cloud droplets. Our simulations indicate that the dominant summer-time Aitken mode is associated with increased efficiency of wet removal, which limits the number of larger aerosols and promotes local new-aerosol formation. We also find an important role of interstitial coagulation in clouds in the Arctic, which limits the number of Aitken-mode aerosols in the non-summer seasons when direct wet removal of these aerosols is inefficient. The summertime Arctic atmosphere is particularly pristine and strongly influenced by natural regional emissions which have poorly understood climate impacts. Especially influenced are the climatic roles of atmospheric particles and clouds. Here we present evidence that ammonia (NH3) emissions from migratory-seabird guano (dung) are the primary contributor to summertime free ammonia levels recently measured in the Canadian Arctic atmosphere. These findings suggest that ammonia from seabird guano is a key factor contributing to bursts of new-particle formation, which are observed every summer in the near-surface atmosphere at Alert, Canada. Chemical transport model simulations show that these newly formed particles can grow by vapour

  16. Microphysical relationships of clouds observed during March 2000 Cloud IOP at SGP Site and important implications

    SciTech Connect

    Lu, C.; Liu, Y.

    2010-03-15

    Cloud droplet size distributions ---- hence the key microphysical quantities of climate importance (e.g., the total droplet concentration, liquid water content, relative dispersion, mean-volume radius, radar reflectivity, and effective radius) are determined by different physical mechanisms such as pre-cloud aerosols, cloud updraft and turbulent entrainment-mixing processes. Therefore, the relationships among these microphysical properties are expected to behave differently in response to aerosols, cloud updrafts and turbulent entrainment-mixing processes. Identifying and quantifying the influences on these microphysical relationships of the various mechanisms is critical for accurately representing cloud microphysics in climate models and for reducing the uncertainty in estimates of aerosol indirect effects. This study first examines the characteristics of the relationships between relative dispersion, droplet concentration, liquid water content, mean-volume radius, effective radius and radar reflectivity calculated from in-situ measurements of cloud droplet size distributions collected during the March 2000 Cloud IOP at the SGP site. The relationships are further analyzed to dissect the effects from different mechanisms/factors (aerosols, updraft, and different turbulent entrainment-mixing processes). Potential applications to improve radar retrievals of cloud properties will be explored as well.

  17. Modelling cloud processing of gases and particles in urban-industrial plumes: Comparison of several meso-scale aerosol forecasting models

    NASA Astrophysics Data System (ADS)

    Gong, W.; Zhang, J.; Kim, S.; Leriche, M.; Frost, G. J.; Grell, G. A.; Mari, C.; McKeen, S. A.; Pinty, J.; Pierre, T.; MacDonald, A.; Leaitch, W. R.

    2010-12-01

    Clouds play an active role in the processing and cycling of chemicals in the atmosphere. Particularly, it is known that a large portion of the atmospheric particulate sulphate, which contributes to a significant fraction of the total PM mass, is produced in cloud via aqueous-phase oxidation. As a result, most of the current aerosol forecast models do include the representation of in-cloud oxidation. On the other hand, the modelling of cloud processing of gases and aerosols and its evaluation are challenging. Past studies have shown that the modeled cloud processing of gases and aerosols depends critically on the predicted cloud microphysics fields. Furthermore, observations suited for evaluating cloud chemistry in models are extremely limited, and there is also the issue with scale disparity (both temporal and spatial) between the model resolution and the observation. This study examines model simulations from three different regional/meso-scale aerosol models, WRF-CHEM (NOAA/ESRL), MESO-NHC (LA/CNRS), and AURAMS (EC), with a focus on cloud processing of urban-industrial plumes. The study case is based on airborne measurements from two flights during the ICARTT field campaign in summer 2004, when the National Research Council of Canada Convair 580 sampled in and below stratocumulus downwind of Chicago along each of the 84°W and 86°W meridians between 40.5 and 42.6°N. The Chicago urban plume was encountered along both meridians, and the observations indicate cloud processing. Model simulations of cloud microphysics, trace gases and aerosol particle concentrations are compared with aircraft observations. Uncertainties in model predicted gases and aerosol concentrations due to model resolution, microphysics and aqueous-phase chemistry parameterization will be assessed.

  18. Cloud Susceptibilities to Ice Nuclei: Microphysical Effects and Dynamical Feedbacks

    NASA Astrophysics Data System (ADS)

    Paukert, Marco; Hoose, Corinna

    2015-04-01

    The impact of aerosols on cloud properties is currently not well established. This is largely attributed to the interdependencies of aerosols and cloud microphysical processes, among which primary ice formation contributes to considerable uncertainties. Although it is known that in a large range of thermodynamic conditions aerosol particles are required to initiate ice formation, identifying and characterizing the effect of specific ice nuclei is among current scientific efforts. Here we attempt to quantify the change of cloud properties with varying aerosol background concentrations. We adapt the concept of susceptibilities for mixed-phase and ice clouds, defining the susceptibility as the derivation of a macrophysical quantity with respect to ice nucleating aerosol concentrations. A focus of our study is the use of different model approaches in order to identify the distinct contributions of both cloud microphysics and cloud-dynamical feedbacks to the overall susceptibility. The classical method is the direct comparison of two independent model runs, where the whole range of microphysical and cloud-dynamical feedbacks contributes to different cloud properties in a perturbed simulation. Our alternative method relies on a single simulation which incorporates multiple executions of the microphysical scheme within the same time step, each "perturbed microphysics" scheme with varying aerosol concentrations and an additional set of cloud particle tracers. Since in the latter case the model dynamics are held constant and only microphysical feedbacks contribute to the properties of perturbed clouds, we can distinguish between the pure microphysical effect and the dynamical enhancement or suppression. For a persistent Arctic mixed-phase stratocumulus cloud layer which is expected to be particularly sensitive to feedback cycles, we show an enhancement of the cloud susceptibility to ice nucleating particles by dynamics of around 50%, but a decay of the enhancement with time

  19. Impacts of alternative fuels in aviation on microphysical aerosol properties and predicted ice nuclei concentration at aircraft cruise altitude

    NASA Astrophysics Data System (ADS)

    Weinzierl, B.; D'Ascoli, E.; Sauer, D. N.; Kim, J.; Scheibe, M.; Schlager, H.; Moore, R.; Anderson, B. E.; Ullrich, R.; Mohler, O.; Hoose, C.

    2015-12-01

    In the past decades air traffic has been substantially growing affecting air quality and climate. According to the International Civil Aviation Authority (ICAO), in the next few years world passenger and freight traffic is expected to increase annually by 6-7% and 4-5%, respectively. One possibility to reduce aviation impacts on the atmosphere and climate might be the replacement of fossil fuels by alternative fuels. However, so far the effects of alternative fuels on particle emissions from aircraft engines and their ability to form contrails remain uncertain. To study the effects of alternative fuels on particle emissions and the formation of contrails, the Alternative Fuel Effects on Contrails and Cruise Emissions (ACCESS) field experiment was conducted in California. In May 2014, the DLR Falcon 20 and the NASA HU-25 jet aircraft were instrumented with an extended aerosol and trace gas payload probing different types of fuels including JP-8 and JP-8 blended with HEFA (Hydroprocessed Esters and Fatty Acids) while the NASA DC8 aircraft acted as the source aircraft for ACCESS-2. Emission measurements were taken in the DC8 exhaust plumes at aircraft cruise level between 9-12 km altitude and at distances between 50 m and 20 km behind the DC8 engines. Here, we will present results from the ACCESS-2 aerosol measurements which show a 30-60% reduction of the non-volatile (mainly black carbon) particle number concentration in the aircraft exhaust for the HEFA-blend compared to conventional JP-8 fuel. Size-resolved particle emission indices show the largest reductions for larger particle sizes suggesting that the HEFA blend contains fewer and smaller black carbon particles. We will combine the airborne measurements with a parameterization of deposition nucleation developed during a number of ice nucleation experiments at the AIDA chamber in Karlsruhe and discuss the impact of alternative fuels on the abundance of potential ice nuclei at cruise conditions.

  20. Sensitivity of high-spectral resolution and broadband thermal infrared nadir instruments to the chemical and microphysical properties of secondary sulfate aerosols in the upper-troposphere/lower-stratosphere

    NASA Astrophysics Data System (ADS)

    Sellitto, Pasquale; Legras, Bernard

    2016-04-01

    The observation of upper-tropospheric/lower-stratospheric (UTLS) secondary sulfate aerosols (SSA) and their chemical and microphysical properties from satellite nadir observations (with better spatial resolution than limb observations) is a fundamental tool to better understand their formation and evolution processes and then to estimate their impact on UTLS chemistry, and on regional and global radiative balance. Thermal infrared (TIR) observations are sensitive to the chemical composition of the aerosols due to the strong spectral variations of the imaginary part of the refractive index in this band and, correspondingly, of the absorption, as a function of the composition Then, these observations are, in principle, well adapted to detect and characterize UTLS SSA. Unfortunately, the exploitation of nadir TIR observations for sulfate aerosol layer monitoring is today very limited. Here we present a study aimed at the evaluation of the sensitivity of TIR satellite nadir observations to the chemical composition and the size distribution of idealised UTLS SSA layers. The sulfate aerosol particles are assumed as binary systems of sulfuric acid/water solution droplets, with varying sulphuric acid mixing ratios. The extinction properties of the SSA, for different sulfuric acid mixing ratios and temperatures, are systematically analysed. The extinction coefficients are derived by means of a Mie code, using refractive indices taken from the GEISA (Gestion et Étude des Informations Spectroscopiques Atmosphériques: Management and Study of Spectroscopic Information) spectroscopic database and log-normal size distributions with different effective radii and number concentrations. High-spectral resolution pseudo-observations are generated using forward radiative transfer calculations performed with the 4A (Automatized Atmospheric Absorption Atlas) radiative transfer model, to estimate the impact of the extinction of idealised aerosol layers, at typical UTLS conditions, on

  1. Effect of In-Plume Aerosol Processing on the Efficacy of Marine Cloud Albedo Enhancement from Controlled Sea-Spray Injections

    NASA Astrophysics Data System (ADS)

    Stevens, R. G.; Spracklen, D.; Korhonen, H.; Pierce, J. R.

    2010-12-01

    The intentional enhancement of cloud albedo via controlled sea-spray injection from ships has been suggested as a possible means to control anthropogenic global warming (1); however, there remains significant uncertainty in the efficacy of this method due to uncertainties in aerosol and cloud microphysics. Recent analysis showed that more sea-spray may be necessary than previously assumed to reach a desired cooling due to nonlinearities in the aerosol/cloud microphysics (2). A major assumption used in (2) is that all sea-spray was emitted uniformly into some oceanic grid boxes, and thus did not account for sub-grid aerosol microphysics within the sea-spray plumes. However, as a consequnce of the fast sea-spray injection rates which are proposed, in the order of 1x10^17 1/s (1), particle concentrations in these plumes may be quite high and particle coagulation may significantly reduce the number of emitted particles and increase their average size. Therefore, it is possible that the emissions necessary to reach a desired cooling may be even larger than currently assumed. We explore the processing of the freshly emitted sea-spray plumes in the Large-Eddy Simulation (LES)/Cloud Resolving Model (CRM) the System for Atmospheric Modelling (SAM, 3) with the online aerosol microphysics module TOMAS (4). We determine how the final number and size of particles (once well mixed with background air) depends on the emission rate and size distribution of the sea-spray plume and on the pre-existing aerosol concentrations and local atmospheric conditions. Finally, we make suggestions for effective size-resolved emissions for use in climate models. (1) Salter, S. et al., Phil. Trans. R. Soc. A., 2008. (2) Korhonen, H. et al., Atmos. Chem. Phys., 10, 4133-4143, 2010. (3) Khairoutdinov, M., and Randall, D.,. J. Atmos. Sci., 60, 607-625, 2003. (4) Pierce, J. and Adams, P., Atmos. Chem. Phys., 9, 1339-1356, 2009.

  2. Design of Nanomaterial Synthesis by Aerosol Processes

    PubMed Central

    Buesser, Beat; Pratsinis, Sotiris E.

    2013-01-01

    Aerosol synthesis of materials is a vibrant field of particle technology and chemical reaction engineering. Examples include the manufacture of carbon blacks, fumed SiO2, pigmentary TiO2, ZnO vulcanizing catalysts, filamentary Ni, and optical fibers, materials that impact transportation, construction, pharmaceuticals, energy, and communications. Parallel to this, development of novel, scalable aerosol processes has enabled synthesis of new functional nanomaterials (e.g., catalysts, biomaterials, electroceramics) and devices (e.g., gas sensors). This review provides an access point for engineers to the multiscale design of aerosol reactors for the synthesis of nanomaterials using continuum, mesoscale, molecular dynamics, and quantum mechanics models spanning 10 and 15 orders of magnitude in length and time, respectively. Key design features are the rapid chemistry; the high particle concentrations but low volume fractions; the attainment of a self-preserving particle size distribution by coagulation; the ratio of the characteristic times of coagulation and sintering, which controls the extent of particle aggregation; and the narrowing of the aggregate primary particle size distribution by sintering. PMID:22468598

  3. UCLALES-SALSA v1.0: a large-eddy model with interactive sectional microphysics for aerosol, clouds and precipitation

    NASA Astrophysics Data System (ADS)

    Tonttila, Juha; Maalick, Zubair; Raatikainen, Tomi; Kokkola, Harri; Kühn, Thomas; Romakkaniemi, Sami

    2017-01-01

    Challenges in understanding the aerosol-cloud interactions and their impacts on global climate highlight the need for improved knowledge of the underlying physical processes and feedbacks as well as their interactions with cloud and boundary layer dynamics. To pursue this goal, increasingly sophisticated cloud-scale models are needed to complement the limited supply of observations of the interactions between aerosols and clouds. For this purpose, a new large-eddy simulation (LES) model, coupled with an interactive sectional description for aerosols and clouds, is introduced. The new model builds and extends upon the well-characterized UCLA Large-Eddy Simulation Code (UCLALES) and the Sectional Aerosol module for Large-Scale Applications (SALSA), hereafter denoted as UCLALES-SALSA. Novel strategies for the aerosol, cloud and precipitation bin discretisation are presented. These enable tracking the effects of cloud processing and wet scavenging on the aerosol size distribution as accurately as possible, while keeping the computational cost of the model as low as possible. The model is tested with two different simulation set-ups: a marine stratocumulus case in the DYCOMS-II campaign and another case focusing on the formation and evolution of a nocturnal radiation fog. It is shown that, in both cases, the size-resolved interactions between aerosols and clouds have a critical influence on the dynamics of the boundary layer. The results demonstrate the importance of accurately representing the wet scavenging of aerosol in the model. Specifically, in a case with marine stratocumulus, precipitation and the subsequent removal of cloud activating particles lead to thinning of the cloud deck and the formation of a decoupled boundary layer structure. In radiation fog, the growth and sedimentation of droplets strongly affect their radiative properties, which in turn drive new droplet formation. The size-resolved diagnostics provided by the model enable investigations of these

  4. Tropical Convective Responses to Microphysical and Radiative Processes: A Sensitivity Study With a 2D Cloud Resolving Model

    NASA Technical Reports Server (NTRS)

    Li, Xiao-Fan; Sui, C.-H.; Lau, K.-M.; Tao, W.-K.

    2004-01-01

    Prognostic cloud schemes are increasingly used in weather and climate models in order to better treat cloud-radiation processes. Simplifications are often made in such schemes for computational efficiency, like the scheme being used in the National Centers for Environment Prediction models that excludes some microphysical processes and precipitation-radiation interaction. In this study, sensitivity tests with a 2D cloud resolving model are carried out to examine effects of the excluded microphysical processes and precipitation-radiation interaction on tropical thermodynamics and cloud properties. The model is integrated for 10 days with the imposed vertical velocity derived from the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment. The experiment excluding the depositional growth of snow from cloud ice shows anomalous growth of cloud ice and more than 20% increase of fractional cloud cover, indicating that the lack of the depositional snow growth causes unrealistically large mixing ratio of cloud ice. The experiment excluding the precipitation-radiation interaction displays a significant cooling and drying bias. The analysis of heat and moisture budgets shows that the simulation without the interaction produces more stable upper troposphere and more unstable mid and lower troposphere than does the simulation with the interaction. Thus, the suppressed growth of ice clouds in upper troposphere and stronger radiative cooling in mid and lower troposphere are responsible for the cooling bias, and less evaporation of rain associated with the large-scale subsidence induces the drying in mid and lower troposphere.

  5. Precipitation and microphysical processes observed by three polarimetric X-band radars and ground-based instrumentation during HOPE

    NASA Astrophysics Data System (ADS)

    Xie, Xinxin; Evaristo, Raquel; Simmer, Clemens; Handwerker, Jan; Trömel, Silke

    2016-06-01

    This study presents a first analysis of precipitation and related microphysical processes observed by three polarimetric X-band Doppler radars (BoXPol, JuXPol and KiXPol) in conjunction with a ground-based network of disdrometers, rain gauges and vertically pointing micro rain radars (MRRs) during the High Definition Clouds and Precipitation for advancing Climate Prediction (HD(CP)2) Observational Prototype Experiment (HOPE) during April and May 2013 in Germany. While JuXPol and KiXPol were continuously observing the central HOPE area near Forschungszentrum Jülich at a close distance, BoXPol observed the area from a distance of about 48.5 km. MRRs were deployed in the central HOPE area and one MRR close to BoXPol in Bonn, Germany. Seven disdrometers and three rain gauges providing point precipitation observations were deployed at five locations within a 5 km × 5 km region, while three other disdrometers were collocated with the MRR in Bonn. The daily rainfall accumulation at each rain gauge/disdrometer location estimated from the three X-band polarimetric radar observations showed very good agreement. Accompanying microphysical processes during the evolution of precipitation systems were well captured by the polarimetric X-band radars and corroborated by independent observations from the other ground-based instruments.

  6. Natural Radionuclides and Isotopic Signatures for Determining Carbonaceous Aerosol Sources, Aerosol Lifetimes, and Washout Processes

    SciTech Connect

    Gaffney, Jeffrey

    2012-12-12

    This is the final technical report. The project description is as follows: to determine the role of aerosol radiative forcing on climate, the processes that control their atmospheric concentrations must be understood, and aerosol sources need to be determined for mitigation. Measurements of naturally occurring radionuclides and stable isotopic signatures allow the sources, removal and transport processes, as well as atmospheric lifetimes of fine carbonaceous aerosols, to be evaluated.

  7. Simulations of microphysical, radiative, and dynamical processes in a continental-scale forest fire smoke plume

    NASA Technical Reports Server (NTRS)

    Westphal, Douglas L.; Toon, Owen B.

    1991-01-01

    The impact of a large forest fire smoke plume on atmospheric processes is studied through a numerical model of meteorology, aerosols, and radiative transfer. The simulated smoke optical depths at 0.63-micron wavelength are in agreement with analyses of satellite data and show values as high as 1.8. The smoke has an albedo of 35 percent, or more than double the clear-sky value, and cools the surface by as much as 5 K. An imaginary refractive index, n sub im, of 0.01 yields results which closely match the observed cooling, single scattering albedo, and the Angstrom wavelength exponent. An n exp im of 0.1, typical of smoke from urban fires, produces 9 K cooling. Coagulation causes the geometric mean radius by number to increase from the initial value of 0.08 micron to a final value of 0.15 micron, while the specific extinction and absorption increase by 40 and 25 percent, respectively.

  8. Exploring microphysical, radiative, dynamic and thermodynamic processes driving fog and low stratus clouds using ground-based Lidar and Radar measurements

    NASA Astrophysics Data System (ADS)

    Haeffelin, Martial

    2016-04-01

    Radiation fog formation is largely influenced by the chemical composition, size and number concentration of cloud condensation nuclei and by heating/cooling and drying/moistening processes in a shallow mixing layer near the surface. Once a fog water layer is formed, its development and dissipation become predominantly controlled by radiative cooling/heating, turbulent mixing, sedimentation and deposition. Key processes occur in the atmospheric surface layer, directly in contact with the soil and vegetation, and throughout the atmospheric column. Recent publications provide detailed descriptions of these processes for idealized cases using very high-resolution models and proper representation of microphysical processes. Studying these processes in real fog situations require atmospheric profiling capabilities to monitor the temporal evolution of key parameters at several heights (surface, inside the fog, fog top, free troposphere). This could be done with in-situ sensors flown on tethered balloons or drones, during dedicated intensive field campaigns. In addition Backscatter Lidars, Doppler Lidars, Microwave Radiometers and Cloud Doppler Radars can provide more continuous, yet precise monitoring of key parameters throughout the fog life cycle. The presentation will describe how Backscatter Lidars can be used to study the height and kinetics of aerosol activation into fog droplets. Next we will show the potential of Cloud Doppler Radar measurements to characterize the temporal evolution of droplet size, liquid water content, sedimentation and deposition. Contributions from Doppler Lidars and Microwave Radiometers will be discussed. This presentation will conclude on the potential to use Lidar and Radar remote sensing measurements to support operational fog nowcasting.

  9. Aerosol Mass Loading, Mixing State, Size and Number in Present Day (2000) and Future (2100): Study with the Advanced Particle Microphysics (APM) module in the Community Earth System Model (CESM)

    NASA Astrophysics Data System (ADS)

    Luo, G.; Yu, F.

    2014-12-01

    Aerosols affect the global energy budget by scattering and absorbing sunlight (direct effects) and by changing the microphysical properties, lifetime, and coverage of clouds (indirect effects). One of the key challenges in quantifying the aerosol direct and indirect effects is to deep our understanding about the size distribution, size-resolved composition, and mixing state of aerosols. However, detailed information on size distribution and mixing state is often not available or incomplete in current climate models. Here, we incorporated APM into CESM. APM is a multi-type, multi-component (sulfate, nitrate, ammonium, SOA, BC, OC, dust, and sea salt), size-resolved particle microphysics model. Online chemistry, up-to-date nucleation, oxidation aging of medium-volatile and semi-volatile organic gases, aerosol-cloud interaction with stratiform cloud, shallow convection cloud, and deep convection cloud are considered. The amounts of secondary species coated on primary particles, through condensation, coagulation, equilibrium uptake, and aqueous chemistry, are also tracked. Model results are compared with aerosol mass observed by IMPROVE/EMEP, vertical structure of global particle number from aircraft-based field campaigns, particle and cloud condensation nuclei number at ground-based stations, aerosol optical properties retrieved by several satellites. Model results can capture the major characteristics shown in these observations. With this model system, we find that global burdens of sulfate, nitrate, ammonium, BC, OC from 2000 to 2100, under scenario RCP 4.5 where total radiative forcing is stabilized before 2100, are decreased by 44%, 50%, 43%, 40%, 40%, respectively. Dust and sea salt increase slightly. Global burdens of secondary species coated on BCOC, dust, and sea salt are deceased by 34%, 30% and 60%, respectively. Global averaged aerosol number in the lower troposphere (from surface to 3 km) is significantly decreased, especially for particles smaller than

  10. Stratospheric Aerosol--Observations, Processes, and Impact on Climate

    NASA Technical Reports Server (NTRS)

    Kresmer, Stefanie; Thomason, Larry W.; von Hobe, Marc; Hermann, Markus; Deshler, Terry; Timmreck, Claudia; Toohey, Matthew; Stenke, Andrea; Schwarz, Joshua P.; Weigel, Ralf; Fueglistaler, Stephan; Prata, Fred J.; Vernier, Jean-Paul; Schlager, Hans; Barnes, John E.; Antuna-Marrero, Juan-Carlos; Fairlie, Duncan; Palm, Mathias; Mahieu, Emmanuel; Notholt, Justus; Rex, Markus; Bingen, Christine; Vanhellemont, Filip; Bourassa, Adam; Plane, John M. C.; Klocke, Daniel; Carn, Simon A.; Clarisse, Lieven; Trickl, Thomas; Neeley, Ryan; James, Alexander D.; Rieger, Landon; Wilson, James C.; Meland, Brian

    2016-01-01

    Interest in stratospheric aerosol and its role in climate have increased over the last decade due to the observed increase in stratospheric aerosol since 2000 and the potential for changes in the sulfur cycle induced by climate change. This review provides an overview about the advances in stratospheric aerosol research since the last comprehensive assessment of stratospheric aerosol was published in 2006. A crucial development since 2006 is the substantial improvement in the agreement between in situ and space-based inferences of stratospheric aerosol properties during volcanically quiescent periods. Furthermore, new measurement systems and techniques, both in situ and space based, have been developed for measuring physical aerosol properties with greater accuracy and for characterizing aerosol composition. However, these changes induce challenges to constructing a long-term stratospheric aerosol climatology. Currently, changes in stratospheric aerosol levels less than 20% cannot be confidently quantified. The volcanic signals tend to mask any nonvolcanically driven change, making them difficult to understand. While the role of carbonyl sulfide as a substantial and relatively constant source of stratospheric sulfur has been confirmed by new observations and model simulations, large uncertainties remain with respect to the contribution from anthropogenic sulfur dioxide emissions. New evidence has been provided that stratospheric aerosol can also contain small amounts of nonsulfatematter such as black carbon and organics. Chemistry-climate models have substantially increased in quantity and sophistication. In many models the implementation of stratospheric aerosol processes is coupled to radiation and/or stratospheric chemistry modules to account for relevant feedback processes.

  11. Process-model simulations of cloud albedo enhancement by aerosols in the Arctic

    PubMed Central

    Kravitz, Ben; Wang, Hailong; Rasch, Philip J.; Morrison, Hugh; Solomon, Amy B.

    2014-01-01

    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. PMID:25404677

  12. 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

  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. A Sensitivity Study of Radiative Fluxes at the Top of Atmosphere to Cloud-Microphysics and Aerosol Parameters in the Community Atmosphere Model CAM5

    SciTech Connect

    Zhao, Chun; Liu, Xiaohong; Qian, Yun; Yoon, Jin-Ho; Hou, Zhangshuan; Lin, Guang; McFarlane, Sally A.; Wang, Hailong; Yang, Ben; Ma, Po-Lun; Yan, Huiping; Bao, Jie

    2013-11-08

    In this study, we investigated the sensitivity of net radiative fluxes (FNET) at the top of atmosphere (TOA) to 16 selected uncertain parameters mainly related to the cloud microphysics and aerosol schemes in the Community Atmosphere Model version 5 (CAM5). We adopted a quasi-Monte Carlo (QMC) sampling approach to effectively explore the high dimensional parameter space. The output response variables (e.g., FNET) were simulated using CAM5 for each parameter set, and then evaluated using generalized linear model analysis. In response to the perturbations of these 16 parameters, the CAM5-simulated global annual mean FNET ranges from -9.8 to 3.5 W m-2 compared to the CAM5-simulated FNET of 1.9 W m-2 with the default parameter values. Variance-based sensitivity analysis was conducted to show the relative contributions of individual parameter perturbation to the global FNET variance. The results indicate that the changes in the global mean FNET are dominated by those of cloud forcing (CF) within the parameter ranges being investigated. The size threshold parameter related to auto-conversion of cloud ice to snow is confirmed as one of the most influential parameters for FNET in the CAM5 simulation. The strong heterogeneous geographic distribution of FNET variation shows parameters have a clear localized effect over regions where they are acting. However, some parameters also have non-local impacts on FNET variance. Although external factors, such as perturbations of anthropogenic and natural emissions, largely affect FNET variations at the regional scale, their impact is weaker than that of model internal parameters in terms of simulating global mean FNET in this study. The interactions among the 16 selected parameters contribute a relatively small portion of the total FNET variations over most regions of the globe. This study helps us better understand the CAM5 model behavior associated with parameter uncertainties, which will aid the next step of reducing model

  15. 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

  16. Multiscale Precipitation Processes Over Mountain Terrain - Landform and Vegetation Controls of Microphysics and Convection in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Barros, A. P.; Wilson, A. M.; Sun, X.; Duan, Y.

    2015-12-01

    Recent precipitation observations in mountainous regions do not exhibit the classical orographic enhancement with elevation, especially where fog and multi-layer clouds are persistent. The role of landform in modulating moisture convergence patterns and constraining the thermodynamic environment that supports the development of complex vertical structures of clouds and precipitation is discussed first using observations and model results from the IPHEx (Integrated Precipitation and Hydrology Experiment) field campaign in the Southern Appalachian Mountains (SAM). Analysis of the complex spatial heterogeneity of precipitation microphysics in the SAM suggests that seeder-feeder interactions (SFI) among stratiform precipitation, low level clouds (LLC), and fog play a governing role on the diurnal and seasonal cycles of observed precipitation regimes. Further, in the absence of synoptic-scale forcing, results suggest that evapotranspiration makes a significant contribution to the moisture budget in the lower atmosphere, creating super-saturation conditions favorable to CCN activation, LLC formation, and light rainfall. To investigate the role of evapotranspiration on the diurnal cycle of mountain precipitation further, range-scale modeling studies were conducted in the Central Andes. Specifically, high resolution WRF simulations for realistic and quasi-idealized ET withdrawal case-studies show that evapotranspiration fluxes modulated by landform govern convective activity in the lower troposphere, including cloud formation and precipitation processes that account for daily precipitation amounts as high as 50-70% depending on synoptic conditions and season. These studies suggest multiscale vegetation controls of orographic precipitation processes via atmospheric instability on the one hand, and low level super-saturation and local microphysics on the other. A conceptual model of multiscale interactions among vegetation, landform and moist processes over complex

  17. Study of the microphysical properties in stratus clouds on the Romanian Black Sea coast

    NASA Astrophysics Data System (ADS)

    Boscornea, Andreea; Stefan, Sabina; Sorin Vajaiac, Nicolae

    2016-04-01

    Stratocumulus clouds play a critical role in the Earth's climate system due to their spatial and temporal large extent. For this reason, this study aims to highlight the significant differences of microphysical properties of maritime and continental stratus clouds and By using the ATMOSLAB research aircraft were examined aerosol and microphysical properties, as well as the thermodynamics of the marine boundary layer in and around the Black Sea (between Mangalia, N: 43 48' 34,6'', E: 28̊ 35' 25,12'' and Navodari City N: 44̊ 19' 02'', E: 28̊ 36' 55,24''). More than 10 h measurements obtained by a Cloud Aerosol and Precipitation Spectrometer and the HAWKEYE included aerosol, CCN, cloud droplet and drizzle drop concentrations, air temperatures, liquid water content, real time cloud droplet and ice crystals images and marine aerosol measurements above the sea surface. The over 15 flight legs in clouds (minimum altitude 250 m and maximum altitude 4000 m) and the 4 flight legs performed directly above the sea surface (altitude 120 m) from the three flight 30 October 2015 and 23 November 2015 conducted to results that provide evidence of indirect aerosol effects associated with natural variability in the cloud and aerosol characteristics. For a complete understanding of the large-scale context processes maintaining and dissipating the continental and marine stratocumulus clouds information from a Sun Photometer (Eforie, N: 44̊ 04' 30'', E: 28̊ 37' 55'', altitude 40 m) and satellite data were used. The interpretation performed on the in situ (into cloud and below cloud) measured data have shown, as it was expected, differences between microphysical parameters for maritime and continental clouds and their dependence on aerosol concentrations. These presented results of in situ measurements of clouds above the Romanian Black Sea Coast are the first reported, so that more data is needed for an enhanced understanding of the maritime/continental microphysical contrasts in

  18. 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

  19. Aerosol Microphysics and Radiation Integration

    DTIC Science & Technology

    2007-09-30

    Al Mandoos (2007), Haboob dust storms of the southern Arabian Peninsula, J. Geophys. Res., in press. Zhang, J., J. S. Reid, S. D. Miller, J. F. Turk...Analysis and Predictions System (NAAPS) and the Coupled Ocean/Atmosphere Mesoscale Prediction System ( COAMPS ®). This work included generation of Navy...Ocean/Atmosphere Mesoscale Prediction System ( COAMPS ?). 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Same as Report

  20. Understanding the Covariance of Microphysics, Thermodynamics, and Dynamics in Mixed Phase Clouds using Airborne Measurements

    NASA Astrophysics Data System (ADS)

    Comstock, J. M.; Fan, J.; Tomlinson, J. M.; Hubbe, J.; Kluzek, C.; Schmid, B.

    2013-12-01

    The physical processes responsible for cloud initiation and lifecycle are complex and involve the interaction between the microphysics, thermodynamics, and dynamics of the atmosphere. Representation of these processes in models requires understanding of the covariance of important parameters at scales that are difficult to resolve in models. We utilize aircraft based measurements in mixed phase clouds to examine the relationship of ice phase partitioning and microphysics with thermodynamic properties and vertical motion. Results are compiled from observational data obtained in convective mixed phase clouds during the Calwater and Two Column Aerosol Project (TCAP) field campaigns conducted using the Department of Energy Gulfstream-1 aircraft. Our results provide a basis for building statistical relationships between microphysical, thermodynamic, and dynamic properties in clouds that are useful for model development and evaluation.

  1. Synergistic use of Lagrangian modelling, satellite- and ground-based measurements for the investigation of volcanic plumes evolution and their impact on the downwind aerosol optical and micro-physical properties: the Etna eruption of 26-27/10/2013

    NASA Astrophysics Data System (ADS)

    Sellitto, Pasquale; di Sarra, Alcide; Corradini, Stefano; Boichu, Marie; Herbin, Hervé; Dubuisson, Philippe; Sèze, Geneviève; Meloni, Daniela; Monteleone, Francesco; Merucci, Luca; Rusalem, Justin; Salerno, Giuseppe; Briole, Pierre; Legras, Bernard

    2015-04-01

    In this contribution we show how the combined use of SO2/ash plume dispersion modelling and remote observations from satellite and ground can be used to study the influence of moderate volcanic activity on the optical and micro-physical characterization of the tropospheric aerosol layer at the regional scale. We analyze the Mount Etna lava fountain and gas/ash emission episode of 26-27/10/2013. This study is based on aerosol and SO2 measurements made at the ENEA Station for Climate Observations (35.52°N, 12.63°E, 50 m asl) on Lampedusa island, on satellite observations, and on a Lagrangian model analysis. The used satellite dataset includes MODIS (MODerate resolution Imaging Spectroradiometer) true colour images, volcanic SO2/ash retrievals and flux estimations, and SEVIRI (Spinning Enhanced Visible and InfraRed Imager) cloud top pressure estimations. Trajectory analyses are made with the FLEXPART (FLEXible PARTicle dispersion model) Lagrangian dispersion model. The combination of MODIS and SEVIRI observations, FLEXPART simulations, and ground-based observations at Lampedusa indicate that SO2 and ash, despite the initial injection at about 7.0 km altitude, could have reached up to 10.0-12.0 km altitude, and influenced the aerosols size distribution downwind at a ground station, at more than 350 km distance, in the Southern sector of the Central Mediterranean. This study indicates that even a relatively small volcanic eruption can have an observable effect on the aerosol layer at the regional scale. Some arguments are given on the likely impact of the secondary sulphate aerosols formed from the conversion of the emitted SO2 on the aerosol size distribution at Lampedusa.

  2. Use of microphysical relationships to discern growth/decay mechanisms of cloud droplets with focus on Z-LWC relationships.

    SciTech Connect

    Liu,Y.; Daum, P.H.; Yum, S.S.; Wang, J.

    2008-05-01

    Cloud droplet size distributions hence the key microphysical quantities (e.g., radar reflectivity, droplet concentration, liquid water content, relative dispersion, and mean-volume radius) are determined by different physical mechanisms, including pre-cloud aerosols as CCNs, cloud updraft, and various turbulent entrainment-mixing processes. Therefore, different relationships among these microphysical properties are expected in response to these various mechanisms. The effect of turbulent entrainment-mixing processes is particularly vexing, with different entrainment-mixing processes likely leading to different microphysical relationships. Cloud radar has been widely used to infer the cloud liquid water content (L) from the measurement of radar reflectivity (Z) using a Z-L relationship. Existing Z-L expressions have been often obtained empirically, and differ substantially (Khain et al. 2008). The discrepancy among Z-L relations, which has been hindering the application of cloud radar in measuring cloud properties, likely stems from the different relationships between the relevant microphysical properties caused by different physical processes. This study first analyzes the Z-L relationship theoretically, and identify the key microphysical properties that affect this relationship, and then address the effects of various processes on the Z-L relationship by discerning the characteristics of the relationships between the relative dispersion, droplet concentration, liquid water content, and mean-volume radius calculated from in-situ measurements of cloud droplet size distributions. Effort is also made to further relate the microphysical relationships to physical processes such as turbulent entrainment-mixing.

  3. Statistical characteristics of cloud variability. Part 2: Implication for parameterizations of microphysical and radiative transfer processes in climate models

    SciTech Connect

    Huang, Dong; Liu, Yangang

    2014-09-17

    The effects of subgrid cloud variability on grid-average microphysical rates and radiative fluxes are examined by use of long-term retrieval products at the Tropical West Pacific, Southern Great Plains, and North Slope of Alaska sites of the Department of Energy's Atmospheric Radiation Measurement program. Four commonly used distribution functions, the truncated Gaussian, Gamma, lognormal, and Weibull distributions, are constrained to have the same mean and standard deviation as observed cloud liquid water content. The probability density functions are then used to upscale relevant physical processes to obtain grid-average process rates. It is found that the truncated Gaussian representation results in up to 30% mean bias in autoconversion rate, whereas the mean bias for the lognormal representation is about 10%. The Gamma and Weibull distribution function performs the best for the grid-average autoconversion rate with the mean relative bias less than 5%. For radiative fluxes, the lognormal and truncated Gaussian representations perform better than the Gamma and Weibull representations. The results show that the optimal choice of subgrid cloud distribution function depends on the nonlinearity of the process of interest, and thus, there is no single distribution function that works best for all parameterizations. Examination of the scale (window size) dependence of the mean bias indicates that the bias in grid-average process rates monotonically increases with increasing window sizes, suggesting the increasing importance of subgrid variability with increasing grid sizes.

  4. What do we need to know to model the microphysical evolution of volcanic clouds and how can we make these measurements?

    NASA Astrophysics Data System (ADS)

    English, J. M.; Toon, O. B.; Mills, M. J.

    2015-12-01

    Large volcanic eruptions can inject millions of tons of ash, sulfate and gaseous precursors into the stratosphere. The magnitude and duration of the volcanic cloud on Earth's temperatures, circulation, clouds, and stratospheric ozone is strongly affected by the microphysical properties of the aerosol size distribution, which can evolve in complex ways. This presentation will cover the impacts and uncertainties associated with microphysical aerosol measurements and modeling of the 1991 Mount Pinatubo eruption, and valuable future measurements after the next large volcanic eruption. These additional measurements can help improve our understanding of stratospheric processes as well as possible consequences of large volcanic eruptions and hypothetical geoengineering scenarios on radiative forcing and chemistry.

  5. Plume Mechanics and Aerosol Growth Processes.

    DTIC Science & Technology

    1987-07-01

    UNIT ELEMENT NO. NO NO ACCESSION NO %. Aberdeen Proving Ground, MD 21010-5423 II 11 TITLE (include Security Classification) Plume Mechanics and...formulation and a finite element sc hem e ......... ..................... 192 c. Diffusion of aerosols in laminar flow in a cylindrical tube...The principal elements are the liquid oil and carrier gas metering systems, the oil vaporizer, coaxial jet system, and the sampling and aerosol

  6. 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.

  7. Sensitivity of WRF to boundary layer parameterizations in simulating a heavy rainfall event using different microphysical schemes. Effect on large-scale processes

    NASA Astrophysics Data System (ADS)

    Efstathiou, G. A.; Zoumakis, N. M.; Melas, D.; Lolis, C. J.; Kassomenos, P.

    2013-10-01

    In this study, the sensitivity of the Weather Research and Forecasting (WRF) model rainfall predictions to the choice of two commonly used boundary layer schemes, is examined through the simulation of an exceptionally heavy rainfall event over Chalkidiki peninsula in northern Greece. This major precipitation event, associated with a case of cyclogenesis over the Aegean Sea, occurred on 8 October 2006 affecting northern and central Greece and causing severe flooding and damage in Chalkidiki peninsula. Simulations with the Yonsei University (YSU) and Mellor-Yamada-Janjic (MYJ) boundary layer parameterizations using three bulk microphysical schemes, showed that MYJ runs had significantly lower predicted rain rates, 24 h accumulations and rain volume regardless of the microphysical scheme used. YSU runs produce more localized areas of intense precipitation especially when they are used in conjunction with the Purdue Lin and WRF Single Moment-6 class microphysics. The general verification results from the comparison of model predictions with available raingauge data over the complex topography of Chalkidiki indicate that configurations using YSU scheme provide better statistical scores for heavy precipitation with ETA microphysics better simulating high precipitation rates and Purdue Lin the 24 h accumulations. It was shown that as a local closure scheme, MYJ produced insufficient vertical mixing confining moisture to lower levels, greatly decreasing condensates and corresponding latent heating that resulted in surface precipitation reduction, compared to YSU runs. Sensitivity tests revealed that condensational heating from the microphysical processes shows a pronounced contribution to the synoptic scale environment by increasing the intensity of larger-scale baroclinicity. Therefore, diabatic heating seems to be one of the most important factors affecting cyclogenesis and controlling the differences in the simulations between the local and non-local BL scheme in this

  8. Aerosol processing in stratiform clouds in ECHAM6-HAM

    NASA Astrophysics Data System (ADS)

    Neubauer, David; Lohmann, Ulrike; Hoose, Corinna

    2013-04-01

    Aerosol processing in stratiform clouds by uptake into cloud particles, collision-coalescence, chemical processing inside the cloud particles and release back into the atmosphere has important effects on aerosol concentration, size distribution, chemical composition and mixing state. Aerosol particles can act as cloud condensation nuclei. Cloud droplets can take up further aerosol particles by collisions. Atmospheric gases may also be transferred into the cloud droplets and undergo chemical reactions, e.g. the production of atmospheric sulphate. Aerosol particles are also processed in ice crystals. They may be taken up by homogeneous freezing of cloud droplets below -38° C or by heterogeneous freezing above -38° C. This includes immersion freezing of already immersed aerosol particles in the droplets and contact freezing of particles colliding with a droplet. Many clouds do not form precipitation and also much of the precipitation evaporates before it reaches the ground. The water soluble part of the aerosol particles concentrates in the hydrometeors and together with the insoluble part forms a single, mixed, larger particle, which is released. We have implemented aerosol processing into the current version of the general circulation model ECHAM6 (Stevens et al., 2013) coupled to the aerosol module HAM (Stier et al., 2005). ECHAM6-HAM solves prognostic equations for the cloud droplet number and ice crystal number concentrations. In the standard version of HAM, seven modes are used to describe the total aerosol. The modes are divided into soluble/mixed and insoluble modes and the number concentrations and masses of different chemical components (sulphate, black carbon, organic carbon, sea salt and mineral dust) are prognostic variables. We extended this by an explicit representation of aerosol particles in cloud droplets and ice crystals in stratiform clouds similar to Hoose et al. (2008a,b). Aerosol particles in cloud droplets are represented by 5 tracers for the

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  10. Microphysics in Multi-scale Modeling System with Unified Physics (Invited)

    NASA Astrophysics Data System (ADS)

    Tao, W.; Lang, S. E.; Wu, D.; Chern, J.

    2013-12-01

    Recently, several major improvements of ice microphysical processes (or schemes) have been developed for cloud-resolving models (Goddard Cumulus Ensemble, GCE, model), regional scale (Weather Research and Forecast, WRF) model and MMF. These improvements include an improved 3-ICE (cloud ice, snow and graupel) scheme (Lang et al. 2011); a 4-ICE (cloud ice, snow, graupel and hail; Lang et al. 2013) scheme and a spectral bin microphysics scheme and two different two-moment microphysics schemes. These models have improved the radiative processes and their interactions with cloud and aerosol. The performance of these schemes has been evaluated by using observational data from TRMM and major field campaigns. In this talk, we will present high-resolution GCE, WRF and MMF model simulations and compare the model results with observations [i.e., Typhoon (Morakot 2009 - an updated simulations), Anvil and Aerosol (AMMA 2006); MCSs (MC3E; 2010; diurnal variation) and CloudSat/TRMM]. In addition, the main issues of the microphysics schemes in high-resolution (1-6 km grid spacing) numerical models will be discussed.

  11. Combined effects of organic aerosol loading and fog processing on organic aerosols oxidation, composition, and evolution.

    PubMed

    Chakraborty, Abhishek; Gupta, Tarun; Tripathi, S N

    2016-12-15

    Chemical characterization of ambient non-refractory submicron aerosols (NR-PM1) was carried out in real time at Kanpur, India. The measurements were performed during the winter (December 2014 to February 2015), and comprised of two very distinct high and low aerosol loading periods coupled with prevalent foggy conditions. The average non-refractory submicron aerosol loading varied significantly from high (HL, ~240μg/m(3)) to low loading (LL, ~100μg/m(3)) period and was dominated by organic aerosols (OA) which contributed more than half (~60%) of the measured aerosol mass. OA source apportionment via positive matrix factorization (PMF) showed drastic changes in the composition of OA from HL to LL period. Overall, O/C (oxygen to carbon) ratios also varied significantly from HL (=0.59) to LL (=0.69) period. Fog episodes (n=17) studied here seem to be reducing the magnitude of the negative impact of OA loading on O/C ratio (OA loading and O/C ratio are anti-correlated, as higher OA loading allows gas to particle partitioning of relatively less oxidized organics) by 60% via aqueous processing. This study provided new insights into the combined effects of OA loading and fog aqueous processing on the evolution of ambient organic aerosols (OA) for the first time.

  12. 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

    2012-01-01

    Recently, a detailed spectral-bin microphysical scheme was implemented into the Goddard Cumulus Ensemble (GCE) model. Atmospheric aerosols are also described using number density size-distribution functions. A spectral-bin microphysical model is very expensive from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep tropical clouds in the west Pacific warm pool region and summertime convection over a mid-latitude continent with different concentrations of CCN: a low clean concentration and a high dirty concentration. The impact of atmospheric aerosol concentration on cloud and precipitation will be investigated.

  13. Formation and growth of photochemical aerosols in Titan's atmosphere

    NASA Astrophysics Data System (ADS)

    Cabane, M.; Chassefiere, E.; Israel, Guy

    1992-04-01

    Recent development in the understanding of the morphology of haze aerosols in Titan's atmosphere, aggregate particles, and their associated optical properties are considered in the flight of a microphysical model of aerosols. Two different phases of the formation process are identified: initial growth of aerosols near the formation altitude by accretion of very small elementary particles; and (2) settling during which particles of about the same size stock together, leading to the formation of aggregates which contain some tens to several hundred monomers. The first phase leads to the formation of nearly spherical 'monomers' (radius approximately equal to 0.05 micrometers). An eulerian microphysical model is used. It is shown that the monomer radius is extremely sensitive to the altitude where aerosols are created. The formation altitude of aerosols is found to lie in the range from 350 to 400 km.

  14. SALSA - a Sectional Aerosol module for Large Scale Applications

    NASA Astrophysics Data System (ADS)

    Kokkola, H.; Korhonen, H.; Lehtinen, K. E. J.; Makkonen, R.; Asmi, A.; Järvenoja, S.; Anttila, T.; Partanen, A.-I.; Kulmala, M.; Järvinen, H.; Laaksonen, A.; Kerminen, V.-M.

    2007-12-01

    The sectional aerosol module SALSA is introduced. The model has been designed to be implemented in large scale climate models, which require both accuracy and computational efficiency. We have used multiple methods to reduce the computational burden of different aerosol processes to optimize the model performance without losing physical features relevant to problematics of climate importance. The optimizations include limiting the chemical compounds and physical processes available in different size sections of aerosol particles; division of the size distribution into size sections using size sections of variable width depending on the sensitivity of microphysical processing to the particles sizes; the total amount of size sections to describe the size distribution is kept to the minimum; furthermore, only the relevant microphysical processes affecting each size section are calculated. The ability of the module to describe different microphysical processes was evaluated against explicit microphysical models and several microphysical models used in air quality models. The results from the current module show good consistency when compared to more explicit models. Also, the module was used to simulate a new particle formation event typical in highly polluted conditions with comparable results to a more explicit model setup.

  15. SALSA - a Sectional Aerosol module for Large Scale Applications

    NASA Astrophysics Data System (ADS)

    Kokkola, H.; Korhonen, H.; Lehtinen, K. E. J.; Makkonen, R.; Asmi, A.; Järvenoja, S.; Anttila, T.; Partanen, A.-I.; Kulmala, M.; Järvinen, H.; Laaksonen, A.; Kerminen, V.-M.

    2008-05-01

    The sectional aerosol module SALSA is introduced. The model has been designed to be implemented in large scale climate models, which require both accuracy and computational efficiency. We have used multiple methods to reduce the computational burden of different aerosol processes to optimize the model performance without losing physical features relevant to problematics of climate importance. The optimizations include limiting the chemical compounds and physical processes available in different size sections of aerosol particles; division of the size distribution into size sections using size sections of variable width depending on the sensitivity of microphysical processing to the particles sizes; the total amount of size sections to describe the size distribution is kept to the minimum; furthermore, only the relevant microphysical processes affecting each size section are calculated. The ability of the module to describe different microphysical processes was evaluated against explicit microphysical models and several microphysical models used in air quality models. The results from the current module show good consistency when compared to more explicit models. Also, the module was used to simulate a new particle formation event typical in highly polluted conditions with comparable results to more explicit model setup.

  16. Sea-salt Aerosol Fluxes from Breaking Waves and Bursting Bubbles: Microphysical, Optical and Spatial Evolution in a Natural Wind-Tunnel

    DTIC Science & Technology

    2005-09-30

    tclarke@soest.hawaii.edu Vladimir N. Kapustin phone: (808) 956-7777 fax: (808) 956-7112 email: kapustin @soest.hawaii.edu Jingchuan...Clarke, A.D., Kapustin , Vladimir N. 2003a: The Shoreline Environment Aerosol Study (SEAS): A Context for Marine Aerosol Measurements Influenced by a...Coastal Environment and Long-Range Transport. Journal of Atmospheric and Oceanic Technology: Vol. 20, No. 10, pp. 1351–1361. 2. Clarke, A.D, Kapustin

  17. Heterogeneous chemistry on Antarctic polar stratospheric clouds - A microphysical estimate of the extent of chemical processing

    NASA Technical Reports Server (NTRS)

    Drdla, K.; Turco, R. P.; Elliott, S.

    1993-01-01

    A detailed model of polar stratospheric clouds (PSCs), which includes nucleation, condensational growth. and sedimentation processes, has been applied to the study of heterogeneous chemical reactions. For the first time, the extent of chemical processing during a polar winter has been estimated for an idealized air parcel in the Antarctic vortex by calculating in detail the rates of heterogeneous reactions on PSC particles. The resulting active chlorine and NO(x) concentrations at first sunrise are analyzed with respect to their influence upon the Antarctic ozone hole using a photochemical model. It is found that the species present at sunrise are primarily influenced by the relative values of the heterogeneous reaction rate constants and the initial gas concentrations. However, the extent of chlorine activation is also influenced by whether N2O5 is removed by reaction with HCl or H2O. The reaction of N2O5 with HCl, which occurs rapidly on type 1 PSCs, activates the chlorine contained in the reservoir species HCl. Hence the presence and surface area of type 1 PSCs early in the winter are crucial in determining ozone depletion.

  18. 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

  19. Microphysics of Pyrocumulonimbus Clouds

    NASA Technical Reports Server (NTRS)

    Jensen, Eric; Ackerman, Andrew S.; Fridlind, Ann

    2004-01-01

    The intense heat from forest fires can generate explosive deep convective cloud systems that inject pollutants to high altitudes. Both satellite and high-altitude aircraft measurements have documented cases in which these pyrocumulonimbus clouds inject large amounts of smoke well into the stratosphere (Fromm and Servranckx 2003; Jost et al. 2004). This smoke can remain in the stratosphere, be transported large distances, and affect lower stratospheric chemistry. In addition recent in situ measurements in pyrocumulus updrafts have shown that the high concentrations of smoke particles have significant impacts on cloud microphysical properties. Very high droplet number densities result in delayed precipitation and may enhance lightning (Andrew et al. 2004). Presumably, the smoke particles will also lead to changes in the properties of anvil cirrus produces by the deep convection, with resulting influences on cloud radiative forcing. In situ sampling near the tops of mature pyrocumulonimbus is difficult due to the high altitude and violence of the storms. In this study, we use large eddy simulations (LES) with size-resolved microphysics to elucidate physical processes in pyrocumulonimbus clouds.

  20. Processing of Ambient Aerosols During Fog Events: Role of Acidity

    NASA Astrophysics Data System (ADS)

    Chakraborty, A.; Gupta, T.; Tripathi, S. N.; Bhattu, D.

    2013-12-01

    Fog is a major processing and removal agent of ambient aerosols. Enhanced secondary organic aerosol (SOA) production has been reported during fog events indicating major role of aqueous processing. Present study was carried out in a heavily polluted city of Kanpur situated in Indo-Gangetic plain of India,from 02- 18 Nov, 2012 and then from 22 Dec, 2012 to 10 January, 2013. 12 fog events were identified from 22 Dec to 10 January based on low visibility (< 300 m) with high liquid water content (~ 0.04 g/m3) and termed as foggy period while remaining as non-foggy period. Foggy period typically showed very high RH (~95%), low temperatures (~2-6°C) compared to non-foggy period. An array of instruments were deployed during this campaign for real time measurement of aerosol physico-chemical properties - High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS), Scanning Mobility Particle Sizer (SMPS), Cloud Combination Probe (CCP), Cloud Condensation Nuclei counter (CCN), fog water collector and Vaisala RH & T sensor. Average aerosol loading during foggy period was 104×44 μg/m3, much higher than 73×49 μg/m3of non-foggy period, but during actual fog events the loading reduced to 85×23 μg/m3 indicating overall aerosol removal by fog. Overall aerosol composition during both the period was dominated by organics which constitutes about 60-70% of the total AMS mass followed by nitrate, but during foggy period sulfate was found to be increased many fold.HR analysis of AMS data revealed noticeable differences in the diurnal average values of O:C ratio between foggy and non -foggy period. Although diurnal O:C ratio was highest around noontime for both period but during fog events, night to early morning O:C ratio was 0.51×0.04, higher than that of non-foggy period 0.44×0.07, clearly indicating enhanced oxidation. AMS data also showed that mode size of all the species specially of organics and sulphate had shifted to a higher diameter during foggy period, an

  1. The dependence of ice microphysics on aerosol concentration in arctic mixed-phase stratus clouds during ISDAC and M-PACE

    SciTech Connect

    Jackson, Robert C.; McFarquhar, Greg; Korolev, Alexei; Earle, Michael; Liu, Peter S.; Lawson, R. P.; Brooks, Sarah D.; Wolde, Mengistu; Laskin, Alexander; Freer, Matthew

    2012-08-14

    Cloud and aerosol data acquired by the National Research Council of Canada (NRC) Convair-580 aircraft in, above, and below single-layer arctic stratocumulus cloud during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in April 2008 were used to test three aerosol indirect effects hypothesized to act in mixed-phase clouds: the riming indirect effect, the glaciation indirect effect, and the cold second indirect effect. The data showed a correlation of R= 0.75 between liquid drop number concentration, Nliq, inside cloud and ambient aerosol number concentration NPCASP below cloud. This, combined with increasing liquid water content LWC with height above cloud base and the nearly constant profile of Nliq, suggested that liquid drops were nucleated from aerosol at cloud base. No strong evidence of a riming indirect effect was observed, but a strong correlation of R = 0.69 between ice crystal number concentration Ni and NPCASP above cloud was noted. Increases in ice nuclei (IN) concentration with NPCASP above cloud combined with the subadiabatic LWC profiles suggest possible mixing of IN from cloud top consistent with the glaciation indirect effect. The higher Nice and lower effective radius rel for the more polluted ISDAC cases compared to data collected in cleaner single-layer stratocumulus conditions during the Mixed-Phase Arctic Cloud Experiment is consistent with the operation of the cold second indirect effect. However, more data in a wider variety of meteorological and surface conditions, with greater variations in aerosol forcing, are required to identify the dominant aerosol forcing mechanisms in mixed-phase arctic clouds.

  2. 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

  3. Enhancement of aerosol responses to changes in emissions over East Asia by gas-oxidant-aerosol coupling and detailed aerosol processes

    NASA Astrophysics Data System (ADS)

    Matsui, H.; Koike, M.

    2016-06-01

    We quantify the responses of aerosols to changes in emissions (sulfur dioxide, black carbon (BC), primary organic aerosol, nitrogen oxides (NOx), and volatile organic compounds) over East Asia by using simulations including gas-oxidant-aerosol coupling, organic aerosol (OA) formation, and BC aging processes. The responses of aerosols to NOx emissions are complex and are dramatically changed by simulating gas-phase chemistry and aerosol processes online. Reduction of NOx emissions by 50% causes a 30-40% reduction of oxidant (hydroxyl radical and ozone) concentrations and slows the formation of sulfate and OA by 20-30%. Because the response of OA to changes in NOx emissions is sensitive to the treatment of emission and oxidation of semivolatile and intermediate volatility organic compounds, reduction of the uncertainty in these processes is necessary to evaluate gas-oxidant-aerosol coupling accurately. Our simulations also show that the sensitivity of aerosols to changes in emissions is enhanced by 50-100% when OA formation and BC aging processes are resolved in the model. Sensitivity simulations show that the increase of NOx emissions from 1850 to 2000 explains 70% (40%) of the enhancement of aerosol mass concentrations (direct radiative effects) over East Asia during that period through enhancement of oxidant concentrations and that this estimation is sensitive to the representation of OA formation and BC aging processes. Our results demonstrate the importance of simultaneous simulation of gas-oxidant-aerosol coupling and detailed aerosol processes. The impact of NOx emissions on aerosol formation will be a key to formulating effective emission reduction strategies such as BC mitigation and aerosol reduction policies in East Asia.

  4. Impacts of Asian Dust on Cloud Microphysics and Precipitation during an Atmospheric River

    NASA Astrophysics Data System (ADS)

    Ault, A. P.; Creamean, J. M.; Williams, C. R.; Gaston, C. J.; Ralph, F. M.; Prather, K. A.

    2009-12-01

    Atmospheric rivers constitute a significant source of precipitation in the mid-latitudes of the northern hemisphere over relatively short time periods, but questions remain about the influence of external factors, such as aerosols, on precipitation locally and regionally. During the CalWater Early Start Campaign (Feb-Mar 2009) sampling aerosol measurements (aerosol time-of-flight mass spectrometry - ATOFMS, aerosol number concentration, CCN concentrations, aerosol size distributions, and PM2.5 mass concentrations) were combined with S-band profiling radar, meteorological, and disdrometer measurements at a remote site in the Central California Sierra Nevada to characterize atmospheric rivers. Aerosol measurements were made of clear air at the site, while rainwater samples were collected. The rainwater samples were then aerosolized and characterized on site using an ATOFMS. S-band radar measured the microphysics of the precipitating cloud and disdrometer measurements characterized the subsequent hydrometeors. During the study an atmospheric river and transported dust interacted, altering cloud properties and shifting the chemical composition of the aerosolized precipitation to markers indicative of transported Asia dust. In contrast, an atmospheric river characterized 8 days earlier was not impacted by Asian dust, leading to different cloud properties and rain water chemical composition. This study examined the impacts of long range transport on precipitation in the Sierras. A greater understanding of the impact of Asian dust on these processes is necessary to properly evaluate long term climate change in the middle latitudes and properly account for transported aerosols in cloud and precipitation models.

  5. Improved identification of the solution space of aerosol microphysical properties derived from the inversion of profiles of lidar optical data, part 1: theory.

    PubMed

    Kolgotin, Alexei; Müller, Detlef; Chemyakin, Eduard; Romanov, Anton

    2016-12-01

    Multiwavelength Raman/high spectral resolution lidars that measure backscatter coefficients at 355, 532, and 1064 nm and extinction coefficients at 355 and 532 nm can be used for the retrieval of particle microphysical parameters, such as effective and mean radius, number, surface-area and volume concentrations, and complex refractive index, from inversion algorithms. In this study, we carry out a correlation analysis in order to investigate the degree of dependence that may exist between the optical data taken with lidar and the underlying microphysical parameters. We also investigate if the correlation properties identified in our study can be used as a priori or a posteriori constraints for our inversion scheme so that the inversion results can be improved. We made the simplifying assumption of error-free optical data in order to find out what correlations exist in the best case situation. Clearly, for practical applications, erroneous data need to be considered too. On the basis of simulations with synthetic optical data, we find the following results, which hold true for arbitrary particle size distributions, i.e., regardless of the modality or the shape of the size distribution function: surface-area concentrations and extinction coefficients are linearly correlated with a correlation coefficient above 0.99. We also find a correlation coefficient above 0.99 for the extinction coefficient versus (1) the ratio of the volume concentration to effective radius and (2) the product of the number concentration times the sum of the squares of the mean radius and standard deviation of the investigated particle size distributions. Besides that, we find that for particles of any mode fraction of the particle size distribution, the complex refractive index is uniquely defined by extinction- and backscatter-related Ångström exponents, lidar ratios at two wavelengths, and an effective radius.

  6. Transport and Microphysics of Aerosols Released by Collapse and Fire of the World Trade Center on September 11, 2001 as Observed by AERONET and MISR

    NASA Astrophysics Data System (ADS)

    Stenchikov, G. L.; Diner, D.; Kahn, R.; Smirnov, A.; Holben, B.

    2005-12-01

    Atmospheric pollution has been studied intensively during the last several decades for its impact on climate, visibility, atmospheric chemistry, and public health. Here we consider the aftermath of the catastrophic aerosol release produced by the collapse of the World Trade Center (WTC) in New York City (NYC) on September 11, 2001. The north and south WTC buildings were attacked at 0846 EDT and 0903 EDT, respectively, on September 11, 2001. The collapse of the WTC South Tower at 0959 EDT followed by the crash of the North Tower at 1029 EDT instantaneously pulverized a vast amount of building material, that was reduced to dust and smoke in nearby streets and the atmosphere above. The remains of the WTC complex covered a 16-acre area known as Ground Zero. Intensive combustion continued until September 14, with temperatures occasionally exceeding 1000 C, producing a steady, elevated source of hazardous gases and aerosols. A detailed spatial and temporal description of the pollution fields' evolution is needed to fully understand their environmental and health impact, but many existing in situ aerosol monitoring stations in the vicinity of the WTC were completely plugged with dust immediately after the collapse. However, the aerosol plume was remotely sensed from the ground and from space. Here we combine numerical modeling of micrometeorological fields and pollution transport using the RAMS/HYPACT modeling system with AERONET and MISR retrievals, to realistically reconstruct plume evolution. AERONET collected plume data in NYC from the roof of the Goddard Institute for Space Studies (GISS) in Upper Manhattan. In NYC, aerosol optical depth was rather low until 1800 UTC on September 12; then it increased to ~0.3 (at 440 nm) by 2130 UTC. On September 13, the optical depth was slightly elevated in the morning and increased further beginning at 1700 UTC, reaching ~0.30 by 2000-2200 UTC. The angstrom exponent increased from 1.8 on September 12 to 2.2 in the late afternoon

  7. Effects of Aerosol Pollution on Clouds over Megacities

    NASA Astrophysics Data System (ADS)

    Sechrist, B.; Jacobson, M. Z.

    2013-12-01

    The correlation between aerosol optical depth (AOD) and cloud properties - principally cloud fraction and cloud optical depth (COD) - is examined using satellite retrievals from the MODIS satellites over Los Angeles and Beijing. Ten Hoeve et al. (2011, Atmos. Chem. Phys, 11(7), 3021-3036) used satellite data to examine the impact of aerosols on warm clouds around Rondonia, Brazil, during the biomass burning season. They found that the COD-AOD relationship exhibits a 'boomerang' shape in which COD initially increases with increasing AOD but then decreases as AOD continues to increase beyond some critical level. This result is thought to reflect the balance between the microphysical and radiative components of a cloud's response to aerosols. The microphysical process dominates at low AOD, while the radiative process dominates at high AOD. This study is analogous to Ten Hoeve et al., but for aerosols derived primarily from fossil fuel combustion rather than biomass burning. Preliminary results will be presented.

  8. What are the Microphysical Properties of Clouds in an Atmosphere without Human-Induced Pollution?

    NASA Astrophysics Data System (ADS)

    Feichter, J.; O'Donnell, D.

    2009-04-01

    The composition of the atmosphere without any man-made emissions is controlled by biogenic and volcanic emissions and wind-driven particle emissions from the pedosphere and the ocean. Biogenic sources include phytoplankton, emission of volatile organic carbon (VOC) compounds by plants and reduced sulfur emissions from vegetation and soils. Besides mineral dust and biomass burning emissions, organics formed from biogenic VOC was likely the dominating aerosol over continents. The different chemical composition of present-day and past climate aerosol loading might affect the subset of aerosols acting as cloud condensation nuclei and subsequently the microphysical properties of clouds. We will present some exploratory model simulations contrasting the climate system in the absence of human-induced aerosol and VOC emissions with that in the presence of such emissions. In particular, cloud properties will be simulated for present-day emissions and contrasted to a scenario where anthropogenic emissions are switched off. The atmospheric general circulation model ECHAM5 used for this study includes the aerosol model HAM and has been extended by an emission model and a module for secondary organic aerosol (SOA). The updated model treats SOA formed from the anthropogenic precursors toluene, xylene and benzene and from the biogenic precursors isoprene and monoterpenes. SOA-specific modelled processes are precursor emissions, gas-phase formation of SOA and gas-aerosol phase partitioning of SOA. Aerosol microphysical and sink processes (dry and wet removal) are treated with minor modifications to the existing model. The VOC emissions from plants are calculated dependent on surface temperature and photosynthetically active radiation flux.

  9. Process-model Simulations of Cloud Albedo Enhancement by Aerosols in the Arctic

    SciTech Connect

    Kravitz, Benjamin S.; Wang, Hailong; Rasch, Philip J.; Morrison, H.; Solomon, Amy

    2014-11-17

    A cloud-resolving model is used to simulate the effectiveness of Arctic marine cloud brightening via injection of cloud condensation nuclei (CCN). 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. Because nearly all of the albedo effects are in the liquid phase due to the removal of ice water by snowfall when ice processes are involved, 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 due to precipitation changes are small.

  10. 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 ...

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

    NASA Astrophysics Data System (ADS)

    Tao, Wei-Kuo; Li, Xiaowen

    2016-06-01

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

  12. A Microphysics-Based Black Carbon Aging Scheme in a Global Chemical Transport Model: Constraints from HIPPO Observations

    NASA Astrophysics Data System (ADS)

    He, C.; Li, Q.; Liou, K. N.; Qi, L.; Tao, S.; Schwarz, J. P.

    2015-12-01

    Black carbon (BC) aging significantly affects its distributions and radiative properties, which is an important uncertainty source in estimating BC climatic effects. Global models often use a fixed aging timescale for the hydrophobic-to-hydrophilic BC conversion or a simple parameterization. We have developed and implemented a microphysics-based BC aging scheme that accounts for condensation and coagulation processes into a global 3-D chemical transport model (GEOS-Chem). Model results are systematically evaluated by comparing with the HIPPO observations across the Pacific (67°S-85°N) during 2009-2011. We find that the microphysics-based scheme substantially increases the BC aging rate over source regions as compared with the fixed aging timescale (1.2 days), due to the condensation of sulfate and secondary organic aerosols (SOA) and coagulation with pre-existing hydrophilic aerosols. However, the microphysics-based scheme slows down BC aging over Polar regions where condensation and coagulation are rather weak. We find that BC aging is primarily dominated by condensation process that accounts for ~75% of global BC aging, while the coagulation process is important over source regions where a large amount of pre-existing aerosols are available. Model results show that the fixed aging scheme tends to overestimate BC concentrations over the Pacific throughout the troposphere by a factor of 2-5 at different latitudes, while the microphysics-based scheme reduces the discrepancies by up to a factor of 2, particularly in the middle troposphere. The microphysics-based scheme developed in this work decreases BC column total concentrations at all latitudes and seasons, especially over tropical regions, leading to large improvement in model simulations. We are presently analyzing the impact of this scheme on global BC budget and lifetime, quantifying its uncertainty associated with key parameters, and investigating the effects of heterogeneous chemical oxidation on BC aging.

  13. The Interaction of Water and Aerosols in the Marine Boundary Layer: A Study of Selected Processes Impacting Radiative Transfer and Cloudiness

    DTIC Science & Technology

    2010-09-30

    pollution sources, with perhaps a significant contribution from soil dust , dominated the aerosol properties. This arises not only from the relative...to determination of aerosol light scattering in the MBL (and thus radiative transfer in the MBL), and CCN activity (and thus of the microphysics of

  14. MAD-VenLA: a microphysical modal representation of clouds for the IPSL Venus GCM

    NASA Astrophysics Data System (ADS)

    Guilbon, Sabrina; Määttänen, Anni; Burgalat, Jérémie; Montmessin, Franck; Stolzenbach, Aurélien; Bekki, Slimane

    2016-10-01

    Venus is enshrouded by 20km-thick clouds, which are composed of sulfuric acid-water solution droplets. Clouds play a crucial role on the climate of the planet. Our goal is to study the formation and evolution of Venusian clouds with microphysical models. The goal of this work is to develop the first full 3D microphysical model of Venus coupled with the IPSL Venus GCM and the photochemical model included (Lebonnois et al. 2010, Stolzenbach et al. 2016).Two particle size distribution representations are generally used in cloud modeling: sectional and modal. The term 'sectional' means that the continuous particle size distribution is divided into a discrete set of size intervals called bins. In the modal approach, the particle size distribution is approximated by a continuous parametric function, typically a log-normal, and prognostic variables are distribution or distribution-integrated parameters (Seigneur et al. 1986, Burgalat et al. 2014). These two representations need to be compared to choose the optimal trade-off between precision and computational efficiency. At high radius resolution, sectional models are computationally too demanding to be integrated in GCMs. That is why, in other GCMs, such as the IPSL Titan GCM, the modal scheme is used (Burgalat et al. 2014).The Venus Liquid Aerosol cloud model (VenLA) and the Modal Dynamics of Venusian Liquid Aerosol cloud model (MAD-VenLA) are respectively the sectional and the modal model discussed here and used for defining the microphysical cloud module to be integrated in the IPSL Venus GCM. We will compare the two models with the key microphysical processes in 0D setting: homogeneous and heterogeneous nucleation, condensation/evaporation and coagulation. Then, MAD-VenLA will be coupled with the IPSL VGCM. The first results of the complete VGCM with microphysics coupled with chemistry will be presented.

  15. Aerosol chemistry in Titan's ionosphere: simultaneous growth and etching processes

    NASA Astrophysics Data System (ADS)

    Carrasco, Nathalie; Cernogora, Guy; Jomard, François; Etcheberry, Arnaud; Vigneron, Jackie

    2016-10-01

    Since the Cassini-CAPS measurements, organic aerosols are known to be present and formed at high altitudes in the diluted and partially ionized medium that is Titan's ionosphere [1]. This unexpected chemistry can be further investigated in the laboratory with plasma experiments simulating the complex ion-neutral chemistry starting from N2-CH4 [2]. Two sorts of solid organic samples can be produced in laboratory experiments simulating Titan's atmospheric reactivity: grains in the volume and thin films on the reactor walls. We expect that grains are more representative of Titan's atmospheric aerosols, but films are used to provide optical indices for radiative models of Titan's atmosphere.The aim of the present study is to address if these two sorts of analogues are chemically equivalent or not, when produced in the same N2-CH4 plasma discharge. The chemical compositions of both these materials are measured by using elemental analysis, XPS analysis and Secondary Ion Mass Spectrometry. We find that films are homogeneous but significantly less rich in nitrogen and hydrogen than grains produced in the same experimental conditions. This surprising difference in their chemical compositions is explained by the efficient etching occurring on the films, which stay in the discharge during the whole plasma duration, whereas the grains are ejected after a few minutes [3]. The impact for our understanding of Titan's aerosols chemical composition is important. Our study shows that chemical growth and etching process are simultaneously at stake in Titan's ionosphere. The more the aerosols stay in the ionosphere, the more graphitized they get through etching process. In order to infer Titan's aerosols composition, our work highlights a need for constraints on the residence time of aerosols in Titan's ionosphere. [1] Waite et al. (2009) Science , 316, p. 870[2] Szopa et al. (2006) PSS, 54, p. 394[3] Carrasco et al. (2016) PSS, 128, p. 52

  16. Uncertainties in BC Estimations: the Role of Atmospheric Processes

    NASA Astrophysics Data System (ADS)

    Vignati, E.; Kloster, S.; Koch, D.; Bauer, S. E.; Dentener, F.; Bond, T.; Sun, H.

    2006-12-01

    Modelling physical and chemical processes involving aerosol particles remains a large source of uncertainties. To characterize the range of uncertainty in these processes on atmospheric BC concentrations, three global models (CTM-TM5, GCM ECHAM5-HAM and GISS GCM) were run using identical BC, particulate organic matter and SO2 emission inventories provided by IIASA for the year 2000. The first two models have the same aerosol dynamic module, while TM5 is also run with a bulk aerosol scheme; the GISS model uses both bulk aerosol and a method of moments aerosol microphysical schemes. We can thus specifically assess the differences in predicted BC concentrations from using the bulk approach and the two microphysical schemes. By comparing the modeled concentrations with an extensive data set of observations, distinguished by measurement methodology, season and region, we will critically evaluate the benefit of using microphysical schemes to simulate the atmospheric BC cycle.

  17. Boundary layer aerosol chemistry during TexAQS/GoMACCS 2006: Insights into aerosol sources and transformation processes

    NASA Astrophysics Data System (ADS)

    Bates, T. S.; Quinn, P. K.; Coffman, D.; Schulz, K.; Covert, D. S.; Johnson, J. E.; Williams, E. J.; Lerner, B. M.; Angevine, W. M.; Tucker, S. C.; Brewer, W. A.; Stohl, A.

    2008-04-01

    The air quality and climate forcing impacts of atmospheric aerosols in a metropolitan region depend on the amount, composition, and size of the aerosol transported into the region; the input and removal of aerosols and aerosol precursors within the region; and the subsequent chemical processing in the atmosphere. These factors were studied in the Houston-Galveston-Gulf of Mexico region, aboard the NOAA R/V Ronald H. Brown during the Texas Air Quality Study and Gulf of Mexico Atmospheric Composition and Climate Study (TexAQS/GoMACCS 2006). The aerosol measured in the Gulf of Mexico during onshore flow (low radon concentrations indicating no contact with land for several days) was highly impacted by Saharan dust and what appear to be ship emissions (acidic sulfate and nitrate). Mean (median) mass concentrations of the total submicrometer and supermicrometer aerosol were 6.5 (4.6) μg m-3 and 17.2 (8.7) μg m-3, respectively. These mass loadings of "background" aerosol are much higher than typically observed in the marine atmosphere and thus have a substantial impact on the radiative energy balance over the Gulf of Mexico and particulate matter (PM) loadings (air quality) in the Houston-Galveston area. As this background aerosol moved onshore, local urban and industrial sources added an organic rich submicrometer component (66% particulate organic matter (POM), 20% sulfate, 14% elemental carbon) but no significant supermicrometer aerosol. The resulting aerosol had mean (median) mass concentrations of the total submicrometer and supermicrometer aerosol of 10.0 (9.1) μg m-3 and 16.8 (11.2) μg m-3, respectively. These air masses, with minimal processing of urban emissions contained the highest SO2/(SO2 + SO4=) ratios and the highest hydrocarbon-like organic aerosol to total organic aerosol ratios (HOA/POM). In contrast, during periods of offshore flow, the aerosol was more processed and, therefore, much richer in oxygenated organic aerosol (OOA). Mean (median) mass

  18. Puerto Rico - 2002 : field studies to resolve aerosol processes.

    SciTech Connect

    Gaffney, J. S.; Marley, N. A.; Ravelo, R.

    1999-10-05

    A number of questions remain concerning homogeneous aerosol formation by natural organics interacting with anthropogenic pollutants. For example, chlorine has been proposed as a potential oxidant in the troposphere because of its very high reactivity with a wide range of organics (Finlayson-Pitts, 1993). Indeed, sea salt aerosol in the presence of ozone has been shown to produce chlorine atoms in heterogeneous photochemical reactions under laboratory conditions. Whether chlorine can initiate oxidation of natural organics such as monoterpene hydrocarbons and can generate homogeneous nucleation or condensable material that contributes to aerosol loadings needs to be assessed. The nighttime reactions of ozone and nitrate radical can also result in monoterpene reactions that contribute to aerosol mass. We are currently planning field studies in Puerto Rico to assess these aerosol issues and other atmospheric chemistry questions. Puerto Rico has a number of key features that make it very attractive for a field study of this sort. The principal feature is the island's very regular meteorology and its position in the Caribbean Sea relative to the easterly trade winds. This meteorology and the island's rectangular shape (100 x 35 miles) make it highly suitable for simplification of boundary layer conditions. In addition, the long stretch between Puerto Rico and the nearest pollution sources in Africa and southern Europe make the incoming background air relatively clean and constant. Furthermore, Puerto Rico has approximately 3.5 million people with a very well defined source region and a central area of rain forest vegetation. These features make Puerto Rico an ideal locale for assessing aerosol processes. The following sections describe specific areas of atmospheric chemistry that can be explored during the proposed field study.

  19. Reversible and irreversible processing of biogenic olefins on acidic aerosols

    NASA Astrophysics Data System (ADS)

    Liggio, J.; Li, S.-M.

    2008-04-01

    Recent evidence has suggested that heterogeneous chemistry of oxygenated hydrocarbons, primarily carbonyls, plays a role in the formation of secondary organic aerosol (SOA); however, evidence is emerging that direct uptake of alkenes on acidic aerosols does occur and can contribute to SOA formation. In the present study, significant uptake of monoterpenes, oxygenated monoterpenes and sesquiterpenes to acidic sulfate aerosols is found under various conditions in a reaction chamber. Proton transfer mass spectrometry is used to quantify the organic gases, while an aerosol mass spectrometer is used to quantify the organic mass uptake and obtain structural information for heterogeneous products. Aerosol mass spectra are consistent with several mechanisms including acid catalyzed olefin hydration, cationic polymerization and organic ether formation, while measurable decreases in the sulfate mass on a per particle basis suggest that the formation of organosulfate compounds is also likely. A portion of the heterogeneous reactions appears to be reversible, consistent with reversible olefin hydration reactions. A slow increase in the organic mass after a fast initial uptake is attributed to irreversible reactions, consistent with polymerization and organosulfate formation. Uptake coefficients (γ) were estimated for a fast initial uptake governed by the mass accommodation coefficient (α) and ranged from 1×10-6-2.5×10-2. Uptake coefficients for a subsequent slower reactive uptake ranged from 1×10-7-1×10-4. These processes may potentially lead to a considerable amount of SOA from the various biogenic hydrocarbons under acidic conditions, which can be highly significant for freshly nucleated aerosols, particularly given the large array of atmospheric olefins.

  20. Assesment of the Indirect and Semi-Direct Aerosol-Effect During ISDAC Through Integrated Observational and Modeling Studies

    SciTech Connect

    Boybeyi, Zafer

    2014-09-29

    The Department of Energy (DOE) awarded George Mason University (GMU) with a research project. This project started on June, 2009 and ended July 2014. Main objectives of this research project are; a) to assess the indirect and semi-direct aerosol effects on microphysical structure and radiative properties of Arctic clouds, b) to assess the impact of feedback between the aerosol-cloud interactions and atmospheric boundary layer (ABL) processes on the surface energy balance, c) to better understand and characterize the important unresolved microphysical processes, aerosol effects, and ABL processes and feedbacks, over meso-γ spatial (~1-2 km) and temporal scales (a few minutes to days), and d) to investigate the scale dependency of microphysical parameterizations and its effect on simulations.

  1. Solar thermal aerosol flow reaction process

    DOEpatents

    Weimer, Alan W.; Dahl, Jaimee K.; Pitts, J. Roland; Lewandowski, Allan A.; Bingham, Carl; Tamburini, Joseph R.

    2005-03-29

    The present invention provides an environmentally beneficial process using concentrated sunlight to heat radiation absorbing particles to carry out highly endothermic gas phase chemical reactions ultimately resulting in the production of hydrogen or hydrogen synthesis gases.

  2. The Influence of the Electric Field on Thunderstorm Microphysical Development Simulated with an Explicit Microphysics Model

    NASA Astrophysics Data System (ADS)

    Phillips, V. T.; Andronache, C.; Sherwood, S.

    2005-05-01

    Electric fields influence the microphysics of aerosol-cloud interactions. Hence, nucleation of ice is sensitive to the charge on nuclei. Furthermore, there is an increase in the collision efficiency when charged aerosol particles collide with droplets ('electroscavenging'), and rates of contact ice nucleation are enhanced by the charge on aerosol particles (Tinsley et al. 2000, Tripathi and Harrison, 2002). In addition, electric fields (EF) affect the collisional growth rate of hydrometeors and their fall velocity. The aim here is to assess how the collection efficiency for the coagulation of hydrometeors may be modified by a typical EF in a thunderstorm. Particular focus is given to effects on the generation of anvil ice particles. This is done by imposing a realistic EF in the control simulation with an Explicit Microphysics Model (EMM) of the storm, observed on 18th July 2002 near Florida during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers - Florida Area Cirrus Experiment (CRYSTAL-FACE), as described by Phillips et al. (2005). An additional aim is to analyze how updraft speed (w) and environmental CCN concentration may affect the charge separation process. The warm rain process is intensified and there is a 30-40% reduction in the anvil ice concentration when an evolving height-dependent EF, typical of continental electrified thunderstorms, is prescribed and applied to the collection efficiencies for coagulation processes in the model. The electric dependence of the collision efficiency for drop-drop collisions is the cause. There is a 150% increase in the broad peak of average mixing ratio of rain near the freezing level (see Figure 1). This boosts the mixing ratio of precipitation-sized ice in the lower half of the mixed phase region, changing the number of charging collisions and depleting the supercooled cloudwater. Primarily because of the high sensitivity of the Hallett-Mossop (H-M) process of ice particle multiplication with respect to

  3. Reversible and irreversible processing of biogenic olefins on acidic aerosols

    NASA Astrophysics Data System (ADS)

    Liggio, J.; Li, S.-M.

    2007-08-01

    Recent evidence has suggested that heterogeneous chemistry of oxygenated hydrocarbons, primarily carbonyls, plays a role in the formation of secondary organic aerosol (SOA); however, evidence is emerging that direct uptake of alkenes on acidic aerosols does occur and can contribute to SOA formation. In the present study, significant uptake of monoterpenes, oxygenated monoterpenes and sesquiterpenes to acidic sulfate aerosols is found under various conditions in a reaction chamber. Proton transfer mass spectrometry is used to quantify the organic gases, while an aerosol mass spectrometer is used to quantify the organic mass uptake and obtain structural information for heterogeneous products. Aerosol mass spectra are consistent with several mechanisms including acid catalyzed olefin hydration, cationic polymerization and organic ester formation, while measurable decreases in the sulfate mass on a per particle basis suggest that the formation of organosulfate compounds is also likely. A portion of the heterogeneous reactions appears to be reversible, consistent with reversible olefin hydration reactions. A slow increase in the organic mass after a fast initial uptake is attributed to irreversible reactions, consistent with polymerization and organosulfate formation. Uptake coefficients (γ) were estimated for a fast initial uptake governed by the mass accommodation coefficient (α) and ranged from 1×10-6-2.5×10-2. Uptake coefficients for a subsequent slower reactive uptake ranged from 1×10-7-1×10-4. These processes are estimated to potentially produce greater than 2.5 μg m-3 of SOA from the various biogenic hydrocarbons under atmospheric conditions, which can be highly significant given the large array of atmospheric olefins.

  4. Effect Of Black Carbon Radiative Heating On Cloud Microphysics Over Indo-Gangetic Basin

    NASA Astrophysics Data System (ADS)

    Ghosh, A.; Tripathi, S. N.

    2008-12-01

    Airborne black carbon (BC), the most significant particulate absorber of solar radiation in the atmosphere, is an important contributor to both global and regional-scale climate forcing (Tripathi et al., 2005). In context of cloud microphysics, freshly emitted pure BC particles are hydrophobic (i.e., bad cloud condensation nuclei (CCN)). However, exposure in the atmosphere may transform BC to a hydrophilic state if these particles are coated with additional materials, such as sulfate and organic carbon (OC). In a recent study, Conant et al. (2002) has examined the effect of radiative heating of BC on the critical supersaturation spectrum of internally mixed aerosols. Two main uncertainties introduced in this work are due to lack of knowledge of actual state of mixing and realistic distributions of different aerosol species. Indo-Gangetic Basin (IGB) in the northern India is one of the most polluted regions in the world. The cloud microphysical processes in IGB are very complex and it requires an in depth investigation for understanding of the aerosol-cloud interaction in the region (Tripathi, et al., 2007). In the present work, an attempt has been made to study the effect of radiative heating due to BC particles coated with hydrophilic materials on cloud microphysics over IGB. For this purpose, we have used (a) a two-layer radiative parameter model based on Mie theory (Toon and Ackerman, 1981) to calculate the particle (monodisperse) absorption cross section; (b) a three-dimensional (3D) radiative transfer model, the spherical harmonics discrete ordinate method (SHDOM) (Evans,1998), which assumes a tropical continental atmosphere, to simulate the 3D spectral actinic flux over the study region; and (c) Extended Köhler theory (Conant et al., 2002) to simulate the effect the BC radiative heating on cloud droplet activation. The solar wavelength spectrum used ranges from 0.2 to 5 micrometer. Following the in situ measurements and modeling studies on mixing state (Dey

  5. Impact of Aerosols on Convective Clouds and Precipitation

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Chen, Jen-Ping; Li, Zhanqing; Wang, Chien; Zhang, Chidong

    2012-01-01

    Aerosols are a critical factor in the atmospheric hydrological cycle and radiation budget. As a major agent for clouds to form and a significant attenuator of solar radiation, aerosols affect climate in several ways. Current research suggests that aerosol effects on clouds could further extend to precipitation, both through the formation of cloud particles and by exerting persistent radiative forcing on the climate system that disturbs dynamics. However, the various mechanisms behind these effects, in particular the ones connected to precipitation, are not yet well understood. The atmospheric and climate communities have long been working to gain a better grasp of these critical effects and hence to reduce the significant uncertainties in climate prediction resulting from such a lack of adequate knowledge. Here we review past efforts and summarize our current understanding of the effect of aerosols on convective precipitation processes from theoretical analysis of microphysics, observational evidence, and a range of numerical model simulations. In addition, the discrepancy between results simulated by models, as well as that between simulations and observations, are presented. Specifically, this paper addresses the following topics: (1) fundamental theories of aerosol effects on microphysics and precipitation processes, (2) observational evidence of the effect of aerosols on precipitation processes, (3) signatures of the aerosol impact on precipitation from largescale analyses, (4) results from cloud-resolving model simulations, and (5) results from large-scale numerical model simulations. Finally, several future research directions for gaining a better understanding of aerosol--cloud-precipitation interactions are suggested.

  6. Impact of Aerosols on Convective Clouds and Precipitation

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Chen, Jen-Ping; Li, Zhanqing; Wang, Chien; Zhang, Chidong

    2011-01-01

    Aerosols are a critical factor in the atmospheric hydrological cycle and radiation budget. As a major reason for clouds to form and a significant attenuator of solar radiation, aerosols affect climate in several ways. Current research suggests that aerosol effects on clouds could further extend to precipitation, both through the formation of cloud particles and by exerting persistent radiative forcing on the climate system that disturbs dynamics. However, the various mechanisms behind these effects, in particular the ones connected to precipitation, are not yet well understood. The atmospheric and climate communities have long been working to gain a better grasp of these critical effects and hence to reduce the significant uncertainties in climate prediction resulting from such a lack of adequate knowledge. The central theme of this paper is to review past efforts and summarize our current understanding of the effect of aerosols on precipitation processes from theoretical analysis of microphysics, observational evidence, and a range of numerical model simulations. In addition, the discrepancy between results simulated by models, as well as that between simulations and observations will be presented. Specifically, this paper will address the following topics: (1) fundamental theories of aerosol effects on microphysics and precipitation processes, (2) observational evidence of the effect of aerosols on precipitation processes, (3) signatures of the aerosol impact on precipitation from large-scale analyses, (4) results from cloud-resolving model simulations, and (5) results from large-scale numerical model simulations. Finally, several future research directions on aerosol - precipitation interactions are suggested.

  7. “Using Statistical Comparisons between SPartICus Cirrus Microphysical Measurements, Detailed Cloud Models, and GCM Cloud Parameterizations to Understand Physical Processes Controlling Cirrus Properties and to Improve the Cloud Parameterizations”

    SciTech Connect

    Woods, Sarah

    2015-12-01

    The dual objectives of this project were improving our basic understanding of processes that control cirrus microphysical properties and improvement of the representation of these processes in the parameterizations. A major effort in the proposed research was to integrate, calibrate, and better understand the uncertainties in all of these measurements.

  8. Effects of Wildfire Pollution on the Microphysical and Electrical Properties of Pyrocumulus

    NASA Astrophysics Data System (ADS)

    Duff, R.; Grant, L. D.; van den Heever, S. C.

    2014-12-01

    Pyrocumulus clouds form over wildfires when hot, smoke-filled air rises, cools and condenses. These clouds have higher cloud condensation nuclei (CCN) concentrations, which affect their microphysical and electrical properties. It is important to better understand pyrocumulus cloud microphysical characteristics and lightning formation, which have implications for the prediction of wildfire growth as well as the radiative and chemical characteristics of the upper troposphere. A recent observational study documented an electrified pyrocumulus over the May 2012 Hewlett Gulch fire located to the west of Fort Collins, Colorado. This cloud produced approximately 20 intracloud lightning flashes, and its electrical activity differed from surrounding convection that was not directly impacted by the fire and associated smoke. The goal of this research is to investigate aerosol-induced cloud-scale microphysical differences between clean clouds and polluted pyrocumulus to better characterize the mechanisms that cause pyrocumulus electrification. In order to address this goal, idealized cloud-resolving model simulations were performed using the Regional Atmospheric Modeling System (RAMS). The model environment was initialized with an average of the 12Z 16 May and 00Z 17 May 2012 observed Denver soundings to represent the conditions when the Hewlett Gulch pyrocumulus occurred. Five simulations were performed using surface aerosol concentrations from 100 to 5000 #/mg. The results demonstrate that in moderately polluted pyrocumulus, rain processes are suppressed while graupel production increases. Extremely polluted pyrocumulus, however, experience a complete shut-down of graupel production, which favors the production of large amounts of liquid water and smaller ice species such as ice crystals and snowflakes. The processes responsible for these microphysical changes, as well as inferred pyrocumulus electrification mechanisms, will be compared with those discussed in previous

  9. Evaluation of moist processes during intense precipitation in km-scale NWP models using remote sensing and in-situ data: Impact of microphysics size distribution assumptions

    SciTech Connect

    Van Weverberg, K.; van Lipzig, N. P. M.; Delobbe, L.

    2011-02-01

    This study investigates the sensitivity of moist processes and surface precipitation during three extreme precipitation events over Belgium to the representation of rain, snow and hail size distributions in a bulk one-moment microphysics parameterisation scheme. Sensitivities included the use of empirically derived relations to calculate the slope parameter and diagnose the intercept parameter of the exponential snow and rain size distributions and sensitivities to the treatment of hail/graupel. A detailed evaluation of the experiments against various high temporal resolution and spatially distributed observational data was performed to understand how moist processes responded to the implemented size distribution modifications. Net vapor consumption by microphysical processes was found to be unaffected by snow or rain size distribution modifications, while it was reduced replacing formulations for hail by those typical for graupel, mainly due to intense sublimation of graupel. Cloud optical thickness was overestimated in all experiments and all cases, likely due to overestimated snow amounts. The overestimation slightly deteriorated by modifying the rain and snow size distributions due to increased snow depositional growth, while it was reduced by including graupel. The latter was mainly due to enhanced cloud water collection by graupel and reduced snow depositional growth. Radar reflectivity and cloud optical thickness could only be realistically represented by inclusion of graupel during a stratiform case, while hail was found indispensable to simulate the vertical reflectivity profile and the surface precipitation structure. Precipitation amount was not much altered by any of the modifications made and the general overestimation was only decreased slightly during a supercell convective case.

  10. Characterisation of aerosol combustible mixtures generated using condensation process

    NASA Astrophysics Data System (ADS)

    Saat, Aminuddin; Dutta, Nilabza; Wahid, Mazlan A.

    2012-06-01

    An accidental release of a liquid flammable substance might be formed as an aerosol (droplet and vapour mixture). This phenomenon might be due to high pressure sprays, pressurised liquid leaks and through condensation when hot vapour is rapidly cooled. Such phenomena require a fundamental investigation of mixture characterisation prior to any subsequent process such as evaporation and combustion. This paper describes characterisation study of droplet and vapour mixtures generated in a fan stirred vessel using condensation technique. Aerosol of isooctane mixtures were generated by expansion from initially a premixed gaseous fuel-air mixture. The distribution of droplets within the mixture was characterised using laser diagnostics. Nearly monosized droplet clouds were generated and the droplet diameter was defined as a function of expansion time. The effect of changes in pressure, temperature, fuel-air fraction and expansion ratio on droplet diameter was evaluated. It is shown that aerosol generation by expansion was influenced by the initial pressure and temperature, equivalence ratio and expansion rates. All these parameters affected the onset of condensation which in turn affected the variation in droplet diameter.

  11. Implementation of the Missing Aerosol Physics into LLNL IMPACT

    SciTech Connect

    Chuang, C

    2005-02-09

    In recent assessments of climate forcing, the Intergovernmental Panel on Climate Change lists aerosol as one o f the most important anthropogenic agents that influence climate. Atmospheric aerosols directly affect the radiative fluxes at the surface and top of the Earth's atmosphere by scattering and/or absorbing radiation. Further, aerosols indirectly change cloud microphysical properties (such as cloud drop effective radius) that also affect the radiative fluxes. However, the estimate of the magnitude of aerosol climatic effect varies widely, and aerosol/cloud interactions remain one of the most uncertain aspects of climate models today. The Atmospheric Sciences Division has formulated a plan to enhance and expand our modeling expertise in aerosol/cloud/climate interactions. Under previous LDRD support, we successfully developed a computationally efficient version of IMPACT to simulate aerosol climatology. This new version contains a compact chemical mechanism for the prediction of sulfate and also predicts the distributions of organic carbon (OC), black carbon (BC), dust, and sea salt. Furthermore, we implemented a radiation package into IMPACT to calculate the radiative forcing and heating/cooling rates by aerosols. This accomplishment built the foundation of our currently funded projects under the NASA Global Modeling and Analysis Program as well as the DOE Atmospheric Radiation Program. Despite the fact that our research is being recognized as an important effort to quantify the effects of anthropogenic aerosols on climate, the major shortcoming of our previous simulations on aerosol climatic effects is the over simplification of spatial and temporal variations of aerosol size distributions that are shaped by complicated nucleation, growth, transport and removal processes. Virtually all properties of atmospheric aerosols and clouds depend strongly on aerosol size distribution. Moreover, molecular processing on aerosol surfaces alters the hygroscopic

  12. Aerosol composition, sources and processes during wintertime in Beijing, China

    NASA Astrophysics Data System (ADS)

    Sun, Y. L.; Wang, Z. F.; Fu, P. Q.; Yang, T.; Jiang, Q.; Dong, H. B.; Li, J.; Jia, J. J.

    2013-05-01

    Air pollution is a major environmental concern during all seasons in the megacity of Beijing, China. Here we present the results from a winter study that was conducted from 21 November 2011 to 20 January 2012 with an Aerodyne Aerosol Chemical Speciation Monitor (ACSM) and various collocated instruments. The non-refractory submicron aerosol (NR-PM1) species vary dramatically with clean periods and pollution episodes alternating frequently. Compared to summer, wintertime submicron aerosols show much enhanced organics and chloride, which on average account for 52% and 5%, respectively, of the total NR-PM1 mass. All NR-PM1 species show quite different diurnal behaviors between summer and winter. For example, the wintertime nitrate presents a gradual increase during daytime and correlates well with secondary organic aerosol (OA), indicating a dominant role of photochemical production over gas-particle partitioning. Positive matrix factorization was performed on ACSM OA mass spectra, and identified three primary OA (POA) factors, i.e., hydrocarbon-like OA (HOA), cooking OA (COA), and coal combustion OA (CCOA), and one secondary factor, i.e., oxygenated OA (OOA). The POA dominates OA during wintertime, contributing 69%, with the other 31% being SOA. Further, all POA components show pronounced diurnal cycles with the highest concentrations occurring at nighttime. CCOA is the largest primary source during the heating season, on average accounting for 33% of OA and 17% of NR-PM1. CCOA also plays a significant role in chemically resolved particulate matter (PM) pollution as its mass contribution increases linearly as a function of NR-PM1 mass loadings. The SOA, however, presents a reverse trend, which might indicate the limited SOA formation during high PM pollution episodes in winter. The effects of meteorology on PM pollution and aerosol processing were also explored. In particular, the sulfate mass is largely enhanced during periods with high humidity because of fog

  13. Technical Note: Simulation of detailed aerosol chemistry on the global scale using MECCA-AERO

    NASA Astrophysics Data System (ADS)

    Kerkweg, A.; Sander, R.; Tost, H.; Jöckel, P.; Lelieveld, J.

    2007-06-01

    We present the MESSy submodel MECCA-AERO, which simulates both aerosol and gas phase chemistry within one comprehensive mechanism. Including the aerosol phase into the chemistry mechanism increases the stiffness of the resulting set of differential equations. The numerical aspects of the approach followed in MECCA-AERO are presented. MECCA-AERO requires input of an aerosol dynamical/microphysical model to provide the aerosol size and particle number information of the modes/bins for which the chemistry is explicitly calculated. Additional precautions are required to avoid the double counting of processes, especially for sulphate in the aerosol dynamical and the chemistry model. This coupling is explained in detail. To illustrate the capabilities of the new aerosol submodel, examples for species usually treated in aerosol dynamical models are shown. The aerosol chemistry as provided by MECCA-AERO is very sumptuous and not readily applicable for long-term simulations, though it provides a reference to evaluate simplified approaches.

  14. Technical Note: simulation of detailed aerosol chemistry on the global scale using MECCA-AERO

    NASA Astrophysics Data System (ADS)

    Kerkweg, A.; Sander, R.; Tost, H.; Jöckel, P.; Lelieveld, J.

    2007-03-01

    We present the MESSy submodel MECCA-AERO, which simulates both aerosol and gas phase chemistry with the same mechanism. Including the aerosol phase into the chemistry mechanism increases the stiffness of the resulting set of differential equations. The numerical aspects of the approach followed in MECCA-AERO are presented. MECCA-AERO requires input of an aerosol dynamical/microphysical model to provide the aerosol size and particle number information of the modes/bins for which the chemistry is explicitly calculated. Additional precautions are required to avoid the double counting of processes, especially for sulphate in the aerosol dynamical and the chemistry model. This coupling is explained in detail. To illustrate the capabilities of the new aerosol submodel, examples for species usually treated in aerosol dynamical models are shown. The aerosol chemistry as provided by MECCA-AERO is very sumptuous and not readily applicable for long-term simulations, though it provides a reference to evaluate simplified approaches.

  15. Toward a New Era of Research in Aerosol/Cloud/Climate Interactions at LLNL

    SciTech Connect

    Chuang, C,; Dignon, J.; Grant, K.; Connell, P.; Bergman, D.; Rotman, D.; Wright, D.; McGraw, R.; Schwartz, S.

    2000-09-27

    One of the largest uncertainties in simulations of climate change over the industrial period is the impact of anthropogenic aerosols on the Earth's radiation budget. Much of this uncertainty arises from the limited capability for either precisely linking precursor gases to the formation and size distribution of the aerosols or quantitatively describing the existing levels of global aerosol loading. This project builds on our aerosol and chemistry expertise to address each of these uncertainties in a more quantitative fashion than is currently possible. With the current LDRD support, we are in the process to implement an aerosol microphysics module into our global chemistry model to more fundamentally and completely describe the processes that determine the distribution of atmospheric aerosols. Using this new modeling capability, in conjunction with the most current version of NCAR climate model, we will examine the influence of these processes on aerosol direct and indirect climate forcing.

  16. GCM Simulations of the Aerosol Indirect Effect: Sensitivity to Cloud Parameterization and Aerosol Burden

    NASA Technical Reports Server (NTRS)

    Menon, Surabi; DelGenio, Anthony D.; Koch, Dorothy; Tselioudis, George; Hansen, James E. (Technical Monitor)

    2001-01-01

    We describe the coupling of the Goddard Institute for Space Studies (GISS) general circulation model (GCM) to an online sulfur chemistry model and source models for organic matter and sea-salt that is used to estimate the aerosol indirect effect. The cloud droplet number concentration is diagnosed empirically from field experiment datasets over land and ocean that observe droplet number and all three aerosol types simultaneously; corrections are made for implied variations in cloud turbulence levels. The resulting cloud droplet number is used to calculate variations in droplet effective radius, which in turn allows us to predict aerosol effects on cloud optical thickness and microphysical process rates. We calculate the aerosol indirect effect by differencing the top-of-the-atmosphere net cloud radiative forcing for simulations with present-day vs. pre-industrial emissions. Both the first (radiative) and second (microphysical) indirect effects are explored. We test the sensitivity of our results to cloud parameterization assumptions that control the vertical distribution of cloud occurrence, the autoconversion rate, and the aerosol scavenging rate, each of which feeds back significantly on the model aerosol burden. The global mean aerosol indirect effect for all three aerosol types ranges from -1.55 to -4.36 W m(exp -2) in our simulations. The results are quite sensitive to the pre-industrial background aerosol burden, with low pre-industrial burdens giving strong indirect effects, and to a lesser extent to the anthropogenic aerosol burden, with large burdens giving somewhat larger indirect effects. Because of this dependence on the background aerosol, model diagnostics such as albedo-particle size correlations and column cloud susceptibility, for which satellite validation products are available, are not good predictors of the resulting indirect effect.

  17. GCM Simulations of the Aerosol Indirect Effect: Sensitivity to Cloud Parameterization and Aerosol Burden

    NASA Technical Reports Server (NTRS)

    Menon, Surabi; DelGenio, Anthony D.; Koch, Dorothy; Tselioudis, George; Hansen, James E. (Technical Monitor)

    2001-01-01

    We describe the coupling of the Goddard Institute for Space Studies (GISS) general circulation model (GCM) to an online sulfur chemistry model and source models for organic matter and sea-salt that is used to estimate the aerosol indirect effect. The cloud droplet number concentration is diagnosed empirically from field experiment datasets over land and ocean that observe droplet number and all three aerosol types simultaneously; corrections are made for implied variations in cloud turbulence levels. The resulting cloud droplet number is used to calculate variations in droplet effective radius, which in turn allows us to predict aerosol effects on cloud optical thickness and microphysical process rates. We calculate the aerosol indirect effect by differencing the top-of-the-atmosphere net cloud radiative forcing for simulations with present-day vs. pre-industrial emissions. Both the first (radiative) and second (microphysical) indirect effects are explored. We test the sensitivity of our results to cloud parameterization assumptions that control the vertical distribution of cloud occurrence, the autoconversion rate, and the aerosol scavenging rate, each of which feeds back significantly on the model aerosol burden. The global mean aerosol indirect effect for all three aerosol types ranges from -1.55 to -4.36 W/sq m in our simulations. The results are quite sensitive to the pre-industrial background aerosol burden, with low pre-industrial burdens giving strong indirect effects, and to a lesser extent to the anthropogenic aerosol burden, with large burdens giving somewhat larger indirect effects. Because of this dependence on the background aerosol, model diagnostics such as albedo-particle size correlations and column cloud susceptibility, for which satellite validation products are available, are not good predictors of the resulting indirect effect.

  18. Secondary organic aerosol formation through fog processing of VOCs

    NASA Astrophysics Data System (ADS)

    Herckes, P.; Hutchings, J. W.

    2010-07-01

    Volatile Organic Compounds (VOCs) including benzene, toluene, ethylbenzene and xylenes (BTEX) have been determined in highly concentrated amounts (>1 ug/L) in intercepted clouds in northern Arizona (USA). These VOCs are found in concentrations much higher than predicted by partitioning alone. The reactivity of BTEX in the fog/cloud aqueous phase was investigated through laboratory studies. BTEX species showed fast degradation in the aqueous phase in the presence of peroxides and light. Observed half-lives ranged from three and six hours, substantially shorter than the respective gas phase half-lives (several days). The observed reaction rates were on the order of 1 ppb/min but decreased substantially with increasing concentrations of organic matter (TOC). The products of BTEX oxidation reactions were analyzed using HPLC-UV and LCMS. The first generation of products identified included phenol and cresols which correspond to the hydroxyl-addition reaction to benzene and toluene. Upon investigating of multi-generational products, smaller, less volatile species are predominant although a large variety of products is found. Most reaction products have substantially lower vapor pressure and will remain in the particle phase upon droplet evaporation. The SOA generation potential of cloud and fog processing of BTEX was evaluated using simple calculations and showed that in ideal situations these reactions could add up to 9% of the ambient aerosol mass. In more conservative scenarios, the contribution of the processing of BTEX was around 1% of ambient aerosol concentrations. Overall, cloud processing of VOC has the potential to contribute to the atmospheric aerosol mass. However, the contribution will depend upon many factors such as the irradiation, organic matter content in the droplets and droplet lifetime.

  19. Variability in morphology, hygroscopicity, and optical properties of soot aerosols during atmospheric processing

    PubMed Central

    Zhang, Renyi; Khalizov, Alexei F.; Pagels, Joakim; Zhang, Dan; Xue, Huaxin; McMurry, Peter H.

    2008-01-01

    The atmospheric effects of soot aerosols include interference with radiative transfer, visibility impairment, and alteration of cloud formation and are highly sensitive to the manner by which soot is internally mixed with other aerosol constituents. We present experimental studies to show that soot particles acquire a large mass fraction of sulfuric acid during atmospheric aging, considerably altering their properties. Soot particles exposed to subsaturated sulfuric acid vapor exhibit a marked change in morphology, characterized by a decreased mobility-based diameter but an increased fractal dimension and effective density. These particles experience large hygroscopic size and mass growth at subsaturated conditions (<90% relative humidity) and act efficiently as cloud-condensation nuclei. Coating with sulfuric acid and subsequent hygroscopic growth enhance the optical properties of soot aerosols, increasing scattering by ≈10-fold and absorption by nearly 2-fold at 80% relative humidity relative to fresh particles. In addition, condensation of sulfuric acid is shown to occur at a similar rate on ambient aerosols of various types of a given mobility size, regardless of their chemical compositions and microphysical structures. Representing an important mechanism of atmospheric aging, internal mixing of soot with sulfuric acid has profound implications on visibility, human health, and direct and indirect climate forcing. PMID:18645179

  20. Variability in morphology, hygroscopicity, and optical properties of soot aerosols during atmospheric processing.

    PubMed

    Zhang, Renyi; Khalizov, Alexei F; Pagels, Joakim; Zhang, Dan; Xue, Huaxin; McMurry, Peter H

    2008-07-29

    The atmospheric effects of soot aerosols include interference with radiative transfer, visibility impairment, and alteration of cloud formation and are highly sensitive to the manner by which soot is internally mixed with other aerosol constituents. We present experimental studies to show that soot particles acquire a large mass fraction of sulfuric acid during atmospheric aging, considerably altering their properties. Soot particles exposed to subsaturated sulfuric acid vapor exhibit a marked change in morphology, characterized by a decreased mobility-based diameter but an increased fractal dimension and effective density. These particles experience large hygroscopic size and mass growth at subsaturated conditions (<90% relative humidity) and act efficiently as cloud-condensation nuclei. Coating with sulfuric acid and subsequent hygroscopic growth enhance the optical properties of soot aerosols, increasing scattering by approximately 10-fold and absorption by nearly 2-fold at 80% relative humidity relative to fresh particles. In addition, condensation of sulfuric acid is shown to occur at a similar rate on ambient aerosols of various types of a given mobility size, regardless of their chemical compositions and microphysical structures. Representing an important mechanism of atmospheric aging, internal mixing of soot with sulfuric acid has profound implications on visibility, human health, and direct and indirect climate forcing.

  1. On the Physicochemical Processes Controlling Organic Aerosol Hygroscopicity

    NASA Astrophysics Data System (ADS)

    Petters, Sarah Suda

    Aerosol particles in the atmosphere can influence air quality and climate through their interaction with water. Aerosols are an important factor in cloud formation because they serve as cloud condensation nuclei (CCN). Organic compounds contribute a large fraction of the atmospheric aerosol mass but their ability to serve as CCN is less certain relative to inorganic compounds. Limitations of the measurement techniques and theoretical gaps in understanding have prevented agreement between predicted and measured CCN. One way to quantify a compound's CCN activity is by the hygroscopicity parameter, kappa. This dissertation presents research towards constraining the variability of organic aerosol kappa at the process level using three approaches: developing a measurement technique; measuring the dependence of kappa on molecular functional groups; and measuring the effect of surface active molecules on kappa for mixtures. Chapter 2 presents a Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) instrument to measure aerosol water uptake at high relative humidity (RH). Measurements up to 99% RH were achieved by improving the precision of aerosol sizing, actively controlling temperature, and calibrating RH between measurements. Osmotic coefficients were obtained within +/-20% for organic aerosols sized between 30 and 200 nanometers. These results may improve water uptake models by providing accurate data at high RH. Chapter 3 presents a study of the sensitivity of kappa to changes in molecular functional group composition for pure compounds. Molecules were synthesized via gas and liquidphase reactions varying the type and location of functional groups, purified by High Performance Liquid Chromatography (HPLC), and routed for CCN measurement. The hydroxyl (-OH) and carbon chain length (-CH2-) changed kappa most, where hydroxyl groups increase kappa and longer carbon chains decrease kappa. This suggests that hydroxyl groups and molecular size dominate the

  2. Processing of aerosol particles within the Habshan pollution plume

    NASA Astrophysics Data System (ADS)

    Semeniuk, T. A.; Bruintjes, R.; Salazar, V.; Breed, D.; Jensen, T.; Buseck, P. R.

    2015-03-01

    The Habshan industrial site in the United Arab Emirates produces a regional-scale pollution plume associated with oil and gas processing, discharging high loadings of sulfates and chlorides into the atmosphere, which interact with the ambient aerosol population. Aerosol particles and trace gas chemistry at this site were studied on two flights in the summer of 2002. Measurements were collected along vertical plume profiles to show changes associated with atmospheric processing of particle and gas components. Close to the outlet stack, particle concentrations were over 10,000 cm-3, dropping to <2000 cm-3 in more dilute plume around 1500 m above the stack. Particles collected close to the stack and within the dilute plume were individually measured for size, morphology, composition, and mixing state using transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy. Close to the stack, most coarse particles consisted of mineral dust and NaCl crystals from burning oil brines, while sulfate droplets dominated the fine mode. In more dilute plume, at least 1500 m above the stack, the particle spectrum was more diverse, with a significant increase in internally mixed particle types. Dilute plume samples consisted of coarse NaCl/silicate aggregates or NaCl-rich droplets, often with a sulfate component, while fine-fraction particles were of mixed cation sulfates, also internally mixed with nanospherical soot or silicates. Thus, both chloride and sulfate components of the pollution plume rapidly reacted with ambient mineral dust to form coated and aggregate particles, enhancing particle size, hygroscopicity, and reactivity of the coarse mode. The fine-fraction sulfate-bearing particles formed in the plume contribute to regional transport of sulfates, while coarse sulfate-bearing fractions locally reduced the SO2 loading through sedimentation. The chloride- and sulfate-bearing internally mixed particles formed in the plume markedly changed the

  3. Observational constraint of drizzle properties and processes in large-eddy simulations from two models with size-resolved microphysics

    NASA Astrophysics Data System (ADS)

    Fridlind, A. M.; Remillard, J.; Ackerman, A. S.; Mechem, D. B.; Kollias, P.; Luke, E. P.; Chuang, P. Y.; Witte, M.; Wood, R.

    2015-12-01

    From the CAP-MBL long-term measurement campaign over the Azores, two low-cloud periods are selected via analysis of ISCCP cloud property matrices. Each is a persistent instance of a low-cloud weather state that the GISS climate model severely underpredicts both over the Azores and globally. Meteorologically, one period is characterized by shallow cumulus clouds in a cold-air outbreak behind a cold front, and the other by overcast stratocumulus clouds in a region dominated by a high-pressure system. Observations and MERRA reanalysis are used to derive specifications used for large-eddy simulations (LES) of each period. For both periods, 6-hour and longer simulations with periodic boundary conditions and uniform large-scale forcings over 10 to 100-km domains capture the structural differences between the two low-cloud periods, only modestly influenced by domain size. Simulations of both periods underestimate sub-mesoscale variability, but represent distributions of cloud top, cloud base, and drizzle extents reasonably well in comparison with observations. Simulated mean Doppler velocities as a function of reflectivity also reproduce observed relationships reasonably well; the most notable deviation is lesser-than-observed Doppler velocity where reflectivity exceeds about -10 dBZ, which occurs only in the cumulus case. However, the range of simulated spectral skewness is substantially underestimated in both cases. To help identify likely causes, the overcast stratocumulus case is also simulated with an independent LES code with size-resolved microphysics, which exhibits some similar biases. Although unavailable from CAP-MBL, in situ measurements of drizzle size distribution from two other campaigns are used to gain insight into the biases. Finally, the significance of Doppler moment biases is evaluated in part by deriving autoconversion and accretion parameterization expressions from simulations with varying collision-coalescence kernel assumptions.

  4. Atmospheric microphysical experiments on an orbital platform

    NASA Technical Reports Server (NTRS)

    Eaton, L. R.

    1974-01-01

    The Zero-Gravity Atmospheric Cloud Physics Laboratory is a Shuttle/Spacelab payload which will be capable of performing a large range of microphysics experiments. This facility will complement terrestrial cloud physics research by allowing many experiments to be performed which cannot be accomplished within the confines of a terrestrial laboratory. This paper reviews the general Cloud Physics Laboratory concept and the experiment scope. The experimental constraints are given along with details of the proposed equipment. Examples of appropriate experiments range from three-dimensional simulation of the earth and planetary atmosphere and of ocean circulation to cloud electrification processes and the effects of atmospheric pollution materials on microphysical processes.

  5. 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.

  6. Combined effects of organic aerosol loading and fog processing on organic aerosols oxidation and composition

    NASA Astrophysics Data System (ADS)

    Chakraborty, Abhishek; Tripathi, Sachchida; Gupta, Tarun

    2016-04-01

    Fog is a natural meteorological phenomenon that occurs throughout the world, it contains substantial quantity of liquid water and generally seen as a natural cleansing agent but it also has the potential to form highly oxidized secondary organic aerosols (SOA) via aqueous processing of ambient aerosols. On the other hand higher organic aerosols (OA) loading tend to decrease the overall oxidation level (O/C) of the particle phase organics, due to enhanced partitioning of less oxidized organics from gas to particle phase. However, combined impact of these two parameters; aqueous oxidation and OA loading, on the overall oxidation ratio (O/C) of ambient OA has never been studied. To assess this, real time ambient sampling using HR-ToF-AMS was carried out at Kanpur, India from 15 December 2014 - 10 February 2015. In first 3 weeks of this campaign, very high OA loading is (134 ± 42 μg/m3) observed (termed as high loading or HL period) while loading is substantially reduced from 2nd January, 2016 (56 ± 20 μg/m3, termed as low loading or LL period) . However, both the loading period was affected by several fog episodes (10 in HL and 7 in LL), thus providing the opportunity of studying the combined effects of fog and OA loading on OA oxidation. It is found that O/C ratio is very strongly anti-correlated with OA loading in both the loading period, however, slope of this ant-correlation is much steep during HL period than in LL period. Source apportionment of OA revealed that there is drastic change in the types of OA from HL to LL period, clearly indicating difference in OA composition from HL to LL period. During foggy night continuous oxidation of OA is observed from early evening to early morning with 15-20% enhancement in O/C ratio, while the same is absent during non-foggy period, clearly indicating the efficient fog processing of ambient OA. It is also found that night time fog aqueous oxidation can be as effective as daytime photo chemistry in oxidation of OA. Fog

  7. Acid rain: Microphysical model

    NASA Technical Reports Server (NTRS)

    Dingle, A. N.

    1980-01-01

    A microphysical model was used to simulate the case of a ground cloud without dilution by entrainment and without precipitation. The numerical integration techniques of the model are presented. The droplet size spectra versus time and the droplet molalities for each value of time are discussed.

  8. Sensitivity of warm-frontal processes to cloud-nucleating aerosol concentrations

    NASA Technical Reports Server (NTRS)

    Igel, Adele L.; Van Den Heever, Susan C.; Naud, Catherine M.; Saleeby, Stephen M.; Posselt, Derek J.

    2013-01-01

    An extratropical cyclone that crossed the United States on 9-11 April 2009 was successfully simulated at high resolution (3-km horizontal grid spacing) using the Colorado State University Regional Atmospheric Modeling System. The sensitivity of the associated warm front to increasing pollution levels was then explored by conducting the same experiment with three different background profiles of cloud-nucleating aerosol concentration. To the authors' knowledge, no study has examined the indirect effects of aerosols on warm fronts. The budgets of ice, cloud water, and rain in the simulation with the lowest aerosol concentrations were examined. The ice mass was found to be produced in equal amounts through vapor deposition and riming, and the melting of ice produced approximately 75% of the total rain. Conversion of cloud water to rain accounted for the other 25%. When cloud-nucleating aerosol concentrations were increased, significant changes were seen in the budget terms, but total precipitation remained relatively constant. Vapor deposition onto ice increased, but riming of cloud water decreased such that there was only a small change in the total ice production and hence there was no significant change in melting. These responses can be understood in terms of a buffering effect in which smaller cloud droplets in the mixed-phase region lead to both an enhanced vapor deposition and decreased riming efficiency with increasing aerosol concentrations. Overall, while large changes were seen in the microphysical structure of the frontal cloud, cloud-nucleating aerosols had little impact on the precipitation production of the warm front.

  9. Secondary Organic Aerosol Production from Cloud Processing of Glycolaldehyde

    NASA Astrophysics Data System (ADS)

    Perri, M. J.; Seitzinger, S.; Turpin, B. J.

    2008-12-01

    Organic particulate matter (PM) formed in the atmosphere (secondary organic aerosol; SOA) is a substantial yet poorly understood contributor to atmospheric PM. Cloud processing is a newly recognized SOA formation pathway. This study investigates the potential for aqueous glycolaldehyde oxidation to produce low volatility products that are retained in the particle phase upon cloud droplet evaporation, increasing PM concentrations aloft. To our knowledge, this is the first confirmation that aqueous oxidation of glycolaldehyde via the hydroxyl radical forms glyoxal and glycolic acid, as previously assumed. Subsequent reactions form formic acid, glyoxylic acid, and oxalic acid as expected. Unexpected products include malonic acid, succinic acid, and higher molecular weight compounds, including oligomers. Predictions of aerosol yields based on these bulk aqueous experiments are presented. Due to (1) the large source strength of glycolaldehyde from precursors such as isoprene and ethene, (2) its water solubility, and (3) the aqueous formation of low volatility products, we predict that cloud processing of glycolaldehyde is an important source of SOA and that incorporation of this SOA formation pathway in chemical transport models will help explain the current under- prediction of organic PM concentrations.

  10. A new WRF-Chem treatment for studying regional-scale impacts of cloud processes on aerosol and trace gases in parameterized cumuli

    DOE PAGES

    Berg, L. K.; Shrivastava, M.; Easter, R. C.; ...

    2015-02-24

    A new treatment of cloud effects on aerosol and trace gases within parameterized shallow and deep convection, and aerosol effects on cloud droplet number, has been implemented in the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) version 3.2.1 that can be used to better understand the aerosol life cycle over regional to synoptic scales. The modifications to the model include treatment of the cloud droplet number mixing ratio; key cloud microphysical and macrophysical parameters (including the updraft fractional area, updraft and downdraft mass fluxes, and entrainment) averaged over the population of shallow clouds, or a single deep convectivemore » cloud; and vertical transport, activation/resuspension, aqueous chemistry, and wet removal of aerosol and trace gases in warm clouds. These changes have been implemented in both the WRF-Chem chemistry packages as well as the Kain–Fritsch (KF) cumulus parameterization that has been modified to better represent shallow convective clouds. Testing of the modified WRF-Chem has been completed using observations from the Cumulus Humilis Aerosol Processing Study (CHAPS). The simulation results are used to investigate the impact of cloud–aerosol interactions on regional-scale transport of black carbon (BC), organic aerosol (OA), and sulfate aerosol. Based on the simulations presented here, changes in the column-integrated BC can be as large as –50% when cloud–aerosol interactions are considered (due largely to wet removal), or as large as +40% for sulfate under non-precipitating conditions due to sulfate production in the parameterized clouds. The modifications to WRF-Chem are found to account for changes in the cloud droplet number concentration (CDNC) and changes in the chemical composition of cloud droplet residuals in a way that is consistent with observations collected during CHAPS. Efforts are currently underway to port the changes described here to the latest version of WRF-Chem, and it

  11. A new WRF-Chem treatment for studying regional-scale impacts of cloud processes on aerosol and trace gases in parameterized cumuli

    SciTech Connect

    Berg, L. K.; Shrivastava, M.; Easter, R. C.; Fast, J. D.; Chapman, E. G.; Liu, Y.; Ferrare, R. A.

    2015-02-24

    A new treatment of cloud effects on aerosol and trace gases within parameterized shallow and deep convection, and aerosol effects on cloud droplet number, has been implemented in the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) version 3.2.1 that can be used to better understand the aerosol life cycle over regional to synoptic scales. The modifications to the model include treatment of the cloud droplet number mixing ratio; key cloud microphysical and macrophysical parameters (including the updraft fractional area, updraft and downdraft mass fluxes, and entrainment) averaged over the population of shallow clouds, or a single deep convective cloud; and vertical transport, activation/resuspension, aqueous chemistry, and wet removal of aerosol and trace gases in warm clouds. These changes have been implemented in both the WRF-Chem chemistry packages as well as the Kain–Fritsch (KF) cumulus parameterization that has been modified to better represent shallow convective clouds. Testing of the modified WRF-Chem has been completed using observations from the Cumulus Humilis Aerosol Processing Study (CHAPS). The simulation results are used to investigate the impact of cloud–aerosol interactions on regional-scale transport of black carbon (BC), organic aerosol (OA), and sulfate aerosol. Based on the simulations presented here, changes in the column-integrated BC can be as large as –50% when cloud–aerosol interactions are considered (due largely to wet removal), or as large as +40% for sulfate under non-precipitating conditions due to sulfate production in the parameterized clouds. The modifications to WRF-Chem are found to account for changes in the cloud droplet number concentration (CDNC) and changes in the chemical composition of cloud droplet residuals in a way that is consistent with observations collected during CHAPS. Efforts are currently underway to port the changes described here to the latest version of WRF-Chem, and it is

  12. Modification of postfrontal convective clouds and precipitation by natural and anthropogenic aerosols

    NASA Astrophysics Data System (ADS)

    Rieger, Daniel; Bangert, Max; Vogel, Bernhard

    2013-04-01

    Shallow postfrontal convective clouds are thought to be sensitive to the aerosol burden. In our case study we present results of model runs, simulating April 25, 2008. On this day a cold front passes Germany from north to south. During this situation the sea salt aerosol transported by the northerly flow into the model domain replaces the preexisting anthropogenic aerosol. We quantify the effect of the aerosol on the microphysical properties of the convective clouds that develop after the passage of the cold front. The model system COSMO-ART (Vogel et al., 2009, Bangert et al., 2010) is a comprehensive online coupled model system to simulate the spatial and temporal distribution of reactive gaseous and particulate matter. It is used to quantify the feedback processes between aerosols and the. state of the atmosphere on the continental to the regional scale with two-way interactions between different atmospheric processes. The model system enables further investigations of the aerosol-cloud-interactions and associated feedback processes. The model framework contains a two-moment cloud microphysics scheme (Seifert and Beheng, 2006) in combination with sophisticated activation parameterizations (Bangert et al., 2012). We carried out sensitivity runs. One applies a bulk microphysics scheme as used in the operational forecasts of the German weather service. In two of them the aerosol was. prescribed (continental, maritime) and kept constant in space and time. In the fourth one we used the full capabilities of COSMO-ART to simulate the dynamic behavior of aerosol and its feedback with radiation and cloud microphysics. We compare our model results with radar data, satellite IR images, and rain gauges.

  13. Advances in fog microphysics research in China

    NASA Astrophysics Data System (ADS)

    Liu, Duanyang; Li, Zihua; Yan, Wenlian; Li, Yi

    2017-02-01

    Fog microphysical research in China based on field experiments obtained many important results in recent 50 years. With the fast development of China's economy, urbanization in the last 30 years, special features of fog microphysical structure also appeared, which did not appear in other countries. This article reviews the fog microphysical research around China, and introduces the effect of urbanization on fog microphysical structure and the microphysical processes as well as macroscopic conditions of radiation fog droplet spectral broadening. Urbanization led to an increase in fog droplet number concentration but decreases in fog liquid water content (LWC) and fog droplet size, as well as a decrease in visibility in large cities. Observations show that the radiation fog could be divided into wide-spectrum one, which is all extremely dense fog with the spectral width more than 40 μm, and narrow-spectrum one, most of which is dense fog with the spectral width less than 22 μm, according to droplet spectral distribution. During developing from dense fog to extremely dense fog, the widespectrum radiation fog is characterized by explosive deepening, that is, within a very short time (about 30 min), the droplet concentration increase by about one order of magnitude, droplet spectral broadening across 20 μm, generally up to 30-40 μm, or even 50 μm. As a result, water content increased obviously, visibility decreased to less than 50 m, when dense fog became extremely dense fog.

  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. 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

  16. Nucleation and growth processes of atmospheric aerosols and clouds

    SciTech Connect

    Schwartz, S.E.; McGraw, R.L.

    1995-11-01

    This project seeks to gain enhanced understanding of the rate of formation and growth of new particles and of cloud droplets as a function of pertinent controlling atmospheric variables, thereby permitting accurate representation of these processes in climate models. Aerosol size distributions are shaped by complex nucleation and growth and mixing processes that are difficult to represent in models, due to the need to accurately represent the evaporation/growth kinetics for each of the billions of discrete cluster sizes in the growth sequence, ranging from molecular clusters to particles of radius of several tenths of a micrometer or greater. A potentially very powerful means of solving this problem may be given by the method of moments (MOM), which tracks the time dependence of just the lower-order radial moments of the size distribution without requiring knowledge of the distribution itself.

  17. Apartment Compartmentalization With an Aerosol-Based Sealing Process

    SciTech Connect

    Maxwell, S.; Berger, D.; Harrington, C.

    2015-03-01

    Air sealing of building enclosures is a difficult and time-consuming process. Current methods in new construction require laborers to physically locate small and sometimes large holes in multiple assemblies and then manually seal each of them. The innovation demonstrated under this research study was the automated air sealing and compartmentalization of buildings through the use of an aerosolized sealant, developed by the Western Cooling Efficiency Center at University of California Davis. CARB sought to demonstrate this new technology application in a multifamily building in Queens, NY. The effectiveness of the sealing process was evaluated by three methods: air leakage testing of overall apartment before and after sealing, point-source testing of individual leaks, and pressure measurements in the walls of the target apartment during sealing.

  18. Assessing the Performance of Computationally Simple and Complex Representations of Aerosol Processes using a Testbed Methodology

    NASA Astrophysics Data System (ADS)

    Fast, J. D.; Ma, P.; Easter, R. C.; Liu, X.; Zaveri, R. A.; Rasch, P.

    2012-12-01

    Predictions of aerosol radiative forcing in climate models still contain large uncertainties, resulting from a poor understanding of certain aerosol processes, the level of complexity of aerosol processes represented in models, and the ability of models to account for sub-grid scale variability of aerosols and processes affecting them. In addition, comparing the performance and computational efficiency of new aerosol process modules used in various studies is problematic because different studies often employ different grid configurations, meteorology, trace gas chemistry, and emissions that affect the temporal and spatial evolution of aerosols. To address this issue, we have developed an Aerosol Modeling Testbed (AMT) to systematically and objectively evaluate aerosol process modules. The AMT consists of the modular Weather Research and Forecasting (WRF) model, a series of 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 a global climate model, Community Atmosphere Model version 5 (CAM5), has also been ported to WRF so that these parameterizations can be tested at various spatial scales and compared directly with field campaign data and other parameterizations commonly used by the mesoscale modeling community. In this study, we evaluate simple and complex treatments of the aerosol size distribution and secondary organic aerosols using the AMT and measurements collected during three field campaigns: the Megacities Initiative Local and Global Observations (MILAGRO) campaign conducted in the vicinity of Mexico City during March 2006, the

  19. Double-moment cloud microphysics scheme for the deep convection parameterization in the GFDL AM3

    NASA Astrophysics Data System (ADS)

    Belochitski, A.; Donner, L.

    2014-12-01

    A double-moment cloud microphysical scheme originally developed by Morrision and Gettelman (2008) for the stratiform clouds and later adopted for the deep convection by Song and Zhang (2011) has been implemented in to the Geophysical Fluid Dynamics Laboratory's atmospheric general circulation model AM3. The scheme treats cloud drop, cloud ice, rain, and snow number concentrations and mixing ratios as diagnostic variables and incorporates processes of autoconversion, self-collection, collection between hydrometeor species, sedimentation, ice nucleation, drop activation, homogeneous and heterogeneous freezing, and the Bergeron-Findeisen process. Such detailed representation of microphysical processes makes the scheme suitable for studying the interactions between aerosols and convection, as well as aerosols' indirect effects on clouds and their roles in climate change. The scheme is first tested in the single column version of the GFDL AM3 using forcing data obtained at the U.S. Department of Energy Atmospheric Radiation Measurment project's Southern Great Planes site. Scheme's impact on SCM simulations is discussed. As the next step, runs of the full atmospheric GCM incorporating the new parameterization are compared to the unmodified version of GFDL AM3. Global climatological fields and their variability are contrasted with those of the original version of the GCM. Impact on cloud radiative forcing and climate sensitivity is investigated.

  20. Quantification of Feedbacks in Aerosol-Cloud-Precipitation Interactions of Mixed-Phase Clouds

    NASA Astrophysics Data System (ADS)

    Glassmeier, F.; Herger, N.; Ramelli, F.; Lohmann, U.

    2014-12-01

    The notion of clouds as buffered or resilient systems implies that generalized feedback processes unaccounted for in climate simulations may lead to an overestimation of the effective radiative forcing due to aerosol-cloud interactions, i.e. cloud lifetime effects. In this contribution, we study the importance of microphysical feedback processes in response to anthropogenic aerosols in orographic mixed-phase clouds. Our methods can be extended to other cloud regimes as well as dynamical and thermodynamical feedbacks. For our simulations, we use the regional atmospheric model COSMO-ART-M7 in a 2D setup with an idealized mountain. To capture major processes from aerosol emission to precipitation, the model is coupled to a modal aerosol scheme and includes aerosol activation and heterogeneous freezing as well as two-moment cold and warm cloud microphysics. We perform simulations with aerosol conditions that vary in amount and chemical composition and thus perturb the warm- and ice-phase pathways of precipitation formation and their mixed-phase interactions. Our analysis is based on quantifying the interaction strength between aerosol, cloud and precipitation variables by susceptibilities, i.e. relative sensitivities d ln(Y) / d ln(X), where the change in variable Y is a response to a perturbation in variable X. We describe how to decompose susceptibilities into a direct response expected from the parameterization and a contribution from feedbacks. Resilience features similar magnitudes but opposite signs for those contributions, resulting in an overall small susceptibility. We find considerable contributions from feedbacks, which appear more important for warm-phase than for cold-phase processes. We do not observe, however, a trend for resilience in mixed-phase cloud microphysics. Moreover, feedback contributions seem of secondary importance when compared to the strong dependence of susceptibilities on the microphysical state of the cloud.

  1. Determination of cloud and aerosol layers using CALIPSO and image processing

    NASA Astrophysics Data System (ADS)

    Alias, A. N.; MatJafri, M. Z.; Lim, H. S.; Abdullah, K.; Saleh, N. Mohd.

    2008-10-01

    The height of cloud and aerosol layers in the atmosphere is believed to affect climate change and air pollution because both of them have important direct effects on the radiation balance of the earth. In this paper, we study the ability of Cloud Aerosol LIDAR and Infrared Pathfinder Satellite Observation (CALIPSO) data to detect, locate and distinguish between cloud and aerosol layers in the atmosphere over Peninsula Malaysia. We also used image processing technique to differentiate between cloud and aerosol layers from the CALIPSO images. The cloud and aerosol layers mostly are seen at troposphere (>10 km) and lower stratosphere (>15km). The results shows that CALIPSO can be used to determine cloud and aerosol layers and image processing technique has successfully distinguished them in the atmosphere.

  2. Monte Carlo simulation of two-component aerosol processes

    NASA Astrophysics Data System (ADS)

    Huertas, Jose Ignacio

    Aerosol processes have been extensively used for production of nanophase materials. However when temperatures and number densities are high, particle agglomeration is a serious drawback for these techniques. This problem can be addressed by encapsulating the particles with a second material before they agglomerate. These particles will agglomerate but the primary particles within them will not. When the encapsulation is later removed, the resulting powder will contain only weakly agglomerated particles. To demonstrate the applicability of the particle encapsulation method for the production of high purity unagglomerated nanosize materials, tungsten (W) and tungsten titanium alloy (W-Ti) particles were synthesized in a sodium/halide flame. The particles were characterized by XRD, SEM, TEM and EDAX. The particles appeared unagglomerated, cubic and hexagonal in shape, and had a size of 30-50 nm. No contamination was detected even after extended exposure to atmospheric conditions. The nanosized W and W-Ti particles were consolidated into pellets of 6 mm diameter and 6-8 mm long. Hardness measurements indicate values 4 times that of conventional tungsten. 100% densification was achieved by hipping the samples. To study the particle encapsulation method, a code to simulate particle formation in two component aerosols was developed. The simulation was carried out using a Monte Carlo technique. This approach allowed for the treatment of both probabilistic and deterministic events. Thus, the coagulation term of the general dynamic equation (GDE) was Monte Carlo simulated, and the condensation term was solved analytically and incorporated into the model. The model includes condensation, coagulation, sources, and sinks for two-component aerosol processes. The Kelvin effect has been included in the model as well. The code is general and does not suffer from problems associated with mass conservation, high rates of condensation and approximations on particle composition. It has

  3. The global aerosol-climate model ECHAM-HAM, version 2: sensitivity to improvements in process representations

    NASA Astrophysics Data System (ADS)

    Zhang, K.; O'Donnell, D.; Kazil, J.; Stier, P.; Kinne, S.; Lohmann, U.; Ferrachat, S.; Croft, B.; Quaas, J.; Wan, H.; Rast, S.; Feichter, J.

    2012-10-01

    This paper introduces and evaluates the second version of the global aerosol-climate model ECHAM-HAM. Major changes have been brought into the model, including new parameterizations for aerosol nucleation and water uptake, an explicit treatment of secondary organic aerosols, modified emission calculations for sea salt and mineral dust, the coupling of aerosol microphysics to a two-moment stratiform cloud microphysics scheme, and alternative wet scavenging parameterizations. These revisions extend the model's capability to represent details of the aerosol lifecycle and its interaction with climate. Nudged simulations of the year 2000 are carried out to compare the aerosol properties and global distribution in HAM1 and HAM2, and to evaluate them against various observations. Sensitivity experiments are performed to help identify the impact of each individual update in model formulation. Results indicate that from HAM1 to HAM2 there is a marked weakening of aerosol water uptake in the lower troposphere, reducing the total aerosol water burden from 75 Tg to 51 Tg. The main reason is the newly introduced κ-Köhler-theory-based water uptake scheme uses a lower value for the maximum relative humidity cutoff. Particulate organic matter loading in HAM2 is considerably higher in the upper troposphere, because the explicit treatment of secondary organic aerosols allows highly volatile oxidation products of the precursors to be vertically transported to regions of very low temperature and to form aerosols there. Sulfate, black carbon, particulate organic matter and mineral dust in HAM2 have longer lifetimes than in HAM1 because of weaker in-cloud scavenging, which is in turn related to lower autoconversion efficiency in the newly introduced two-moment cloud microphysics scheme. Modification in the sea salt emission scheme causes a significant increase in the ratio (from 1.6 to 7.7) between accumulation mode and coarse mode emission fluxes of aerosol number concentration. This

  4. On the Influence of a Simple Microphysics Parametrization on Radiation Fog Modelling: A Case Study During ParisFog

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaojing; Musson-Genon, Luc; Dupont, Eric; Milliez, Maya; Carissimo, Bertrand

    2014-05-01

    A detailed numerical simulation of a radiation fog event with a single column model is presented, which takes into account recent developments in microphysical parametrizations. One-dimensional simulations are performed using the computational fluid dynamics model Code_Saturne and the results are compared to a very detailed in situ dataset collected during the ParisFog campaign, which took place near Paris, France, during the winter 2006-2007. Special attention is given to the detailed and complete diurnal simulations and to the role of microphysics in the fog life cycle. The comparison between the simulated and the observed visibility, in the single-column model case study, shows that the evolution of radiation fog is correctly simulated. Sensitivity simulations show that fog development and dissipation are sensitive to the droplet-size distribution through sedimentation/deposition processes but the aerosol number concentration in the coarse mode has a low impact on the time of fog formation.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  8. Distinct Impacts of Aerosols on an Evolving Continental Cloud System during the RACORO Field Campaign

    NASA Astrophysics Data System (ADS)

    Lin, Y.; Wang, Y.; Zhang, R.; Liu, Y.

    2015-12-01

    Aerosol-cloud interactions have been investigated extensively but still remain high uncertainty due to the complexity of cloud microphysical processes under various dynamic and thermodynamic environments. Cloud-resolving Weather Research and Forecast (CR-WRF) model implemented with a two-moment bulk microphysics and a modified Goddard radiation scheme is employed to investigate aerosol effects on different cloud regimes and their transitions associated with a continental cloud system occurring from 25 May to 27 May, 2009 during the Department of Energy Atmospheric Radiation Measurement Routine AAF Clouds with Low Optical Water Depths Optical Radiative Observations (RACORO) field campaign. The simulated cloud properties and precipitation for the three different cloud regimes, including shallow cumuli, a deep convective cloud (DCC), and a stratus exhibit overall agreements with airborne and ground-based observations. Sensitivity studies with different aerosol scenarios reveal that the responses of cloud micro- and macrophysics to aerosol loading depend on the cloud regimes with monotonic or non-monotonic trend. Aerosol radiative effects modify the atmospheric thermodynamic condition and change the atmospheric stability, which induce different response from aerosol indirect effects. Our results also indicate that the overall aerosol effects on a cloud complex are distinct from those of the individual cloud types. The aerosol-cloud interaction for the different cloud regimes should be evaluated to assess the aerosol direct and indirect radiative forcings on regional and global climate.

  9. Aerosol physical properties and their impact on climate change processes

    NASA Astrophysics Data System (ADS)

    Strzalkowska, Agata; Zielinski, Tymon; Petelski, Tomasz; Makuch, Przemyslaw; Pakszys, Paulina; Markuszewski, Piotr; Piskozub, Jacek; Drozdowska, Violetta; Gutowska, Dorota; Rozwadowska, Anna

    2013-04-01

    Characterizing aerosols involves the specification of not only their spatial and temporal distributions but their multi-component composition, particle size distribution and physical properties as well. Due to their light attenuation and scattering properties, aerosols influence radiance measured by satellite for ocean color remote sensing. Studies of marine aerosol production and transport are important for many earth sciences such as cloud physics, atmospheric optics, environmental pollution studies, and interaction between ocean and atmosphere. It was one of the reasons for the growth in the number of research programs dealing with marine aerosols. Sea salt aerosols are among the most abundant components of the atmospheric aerosol, and thus it exerts a strong influence on radiation, cloud formation, meteorology and chemistry of the marine atmosphere. An accurate understanding and description of these mechanisms is crucial to modeling climate and climate change. This work provides information on combined aerosol studies made with lidars and sun photometers onboard the ship and in different coastal areas. We concentrate on aerosol optical thickness and its variations with aerosol advections into the study area. We pay special attention to the problem of proper data collection and analyses techniques. We showed that in order to detect the dynamics of potential aerosol composition changes it is necessary to use data from different stations where measurements are made using the same techniques. The combination of such information with air mass back-trajectories and data collected at stations located on the route of air masses provides comprehensive picture of aerosol variations in the study area both vertically and horizontally. Acknowledgements: The support for this study was provided by the project Satellite Monitoring of the Baltic Sea Environment - SatBałtyk founded by European Union through European Regional Development Fund contract No. POIG 01

  10. 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

  11. Aqueous phase processing of secondary organic aerosol from isoprene photooxidation

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Monod, A.; Tritscher, T.; Praplan, A. P.; DeCarlo, P. F.; Temime-Roussel, B.; Quivet, E.; Marchand, N.; Dommen, J.; Baltensperger, U.

    2012-07-01

    Transport of reactive air masses into humid and wet areas is highly frequent in the atmosphere, making the study of aqueous phase processing of secondary organic aerosol (SOA) very relevant. We have investigated the aqueous phase processing of SOA generated from gas-phase photooxidation of isoprene using a smog chamber. The SOA collected on filters was extracted by water and subsequently oxidized in the aqueous phase either by H2O2 under dark conditions or by OH radicals in the presence of light, using a photochemical reactor. Online and offline analytical techniques including SMPS, HR-AMS, H-TDMA, TD-API-AMS, were employed for physical and chemical characterization of the chamber SOA and nebulized filter extracts. After aqueous phase processing, the particles were significantly more hygroscopic, and HR-AMS data showed higher signal intensity at m/z 44 and a lower signal intensity at m/z 43, thus showing the impact of aqueous phase processing on SOA aging, in good agreement with a few previous studies. Additional offline measurement techniques (IC-MS, APCI-MS2 and HPLC-APCI-MS) permitted the identification and quantification of sixteen individual chemical compounds before and after aqueous phase processing. Among these compounds, small organic acids (including formic, glyoxylic, glycolic, butyric, oxalic and 2,3-dihydroxymethacrylic acid (i.e. 2-methylglyceric acid)) were detected, and their concentrations significantly increased after aqueous phase processing. In particular, the aqueous phase formation of 2-methylglyceric acid and trihydroxy-3-methylbutanal was correlated with the consumption of 2,3-dihydroxy-2-methyl-propanal, and 2-methylbutane-1,2,3,4-tetrol, respectively, and an aqueous phase mechanism was proposed accordingly. Overall, the aging effect observed here was rather small compared to previous studies, and this limited effect could possibly be explained by the lower liquid phase OH concentrations employed here, and/or the development of oligomers

  12. A Study of the Response of Deep Tropical Clouds to Mesoscale Processes. Part 2; Sensitivities to Microphysics, Radiation, and Surface Fluxes

    NASA Technical Reports Server (NTRS)

    Johnson, Daniel; Tao, Wei-Kuo; Simpson, Joanne

    2004-01-01

    The Goddard Cumulus Ensemble (GCE) model is used to examine the sensitivities of surface fluxes, explicit radiation, and ice microphysical processes on multi-day simulations of deep tropical convection over the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE). The simulations incorporate large-scale advective temperature and moisture forcing, as well as large-scale momentum, that are updated every time step on a periodic lateral boundary grid. This study shows that when surface fluxes are eliminated, the mean atmosphere is much cooler and drier, convection and CAPE are much weaker, precipitation is less, and cloud coverage in stratiform regions much greater. Surface fluxes using the TOGA COARE flux algorithm are weaker than with the aerodynamic formulation, but closer to the observed fluxes. In addition, similar trends noted above for the case without surface fluxes are produced for the TOGA flux case, albeit to a much lesser extent. The elimination of explicit shortwave and longwave radiation is found to have only minimal effects on the mean thermodynamics, convection, and precipitation. However explicit radiation does have a significant impact on cloud temperatures and structure above 200 mb and on the overall mean vertical circulation. The removal of ice processes produces major changes in the structure of the cloud. Much of the liquid water is transported aloft and into anvils above the melting layer (600 mb), leaving narrow, but intense bands of rainfall in convective regions. The elimination of melting processes leads to greater hydrometeor mass below the melting layer, and produces a much warmer and moister boundary layer, leading to a greater mean CAPE. Finally, the elimination of the graupel species has only a small impact on mean total precipitation, thermodynamics, and dynamics of the simulation, but does produce much greater snow mass just above the melting layer. Some of these results differ from previous CRM

  13. Indirect and Semi-Direct Aerosol Campaign: The Impact of Arctic Aerosols on Clouds

    SciTech Connect

    McFarquhar, Greg; Ghan, Steven J.; Verlinde, J.; Korolev, Alexei; Strapp, J. Walter; Schmid, Beat; Tomlinson, Jason M.; Wolde, Mengistu; Brooks, Sarah D.; Cziczo, Daniel J.; Dubey, Manvendra K.; Fan, Jiwen; Flynn, Connor J.; Gultepe, Ismail; Hubbe, John M.; Gilles, Mary K.; Laskin, Alexander; Lawson, Paul; Leaitch, W. R.; Liu, Peter S.; Liu, Xiaohong; Lubin, Dan; Mazzoleni, Claudio; Macdonald, A. M.; Moffet, Ryan C.; Morrison, H.; Ovchinnikov, Mikhail; Shupe, Matthew D.; Turner, David D.; Xie, Shaocheng; Zelenyuk, Alla; Bae, Kenny; Freer, Matthew; Glen, Andrew

    2011-02-01

    A comprehensive dataset of microphysical and radiative properties of aerosols and clouds in the arctic boundary layer in the vicinity of Barrow, Alaska was collected in April 2008 during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) sponsored by the Department of Energy Atmospheric Radiation Measurement (ARM) and Atmospheric Science Programs. The primary aim of ISDAC was to examine indirect effects of aerosols on clouds that contain both liquid and ice water. The experiment utilized the ARM permanent observational facilities at the North Slope of Alaska (NSA) in Barrow. These include a cloud radar, a polarized micropulse lidar, and an atmospheric emitted radiance interferometer as well as instruments specially deployed for ISDAC measuring aerosol, ice fog, precipitation and spectral shortwave radiation. The National Research Council of Canada Convair-580 flew 27 sorties during ISDAC, collecting data using an unprecedented 42 cloud and aerosol instruments for more than 100 hours on 12 different days. Data were obtained above, below and within single-layer stratus on 8 April and 26 April 2008. These data enable a process-oriented understanding of how aerosols affect the microphysical and radiative properties of arctic clouds influenced by different surface conditions. Observations acquired on a heavily polluted day, 19 April 2008, are enhancing this understanding. Data acquired in cirrus on transit flights between Fairbanks and Barrow are improving our understanding of the performance of cloud probes in ice. Ultimately the ISDAC data will be used to improve the representation of cloud and aerosol processes in models covering a variety of spatial and temporal scales, and to determine the extent to which long-term surface-based measurements can provide retrievals of aerosols, clouds, precipitation and radiative heating in the Arctic.

  14. Aerosol-Cloud-Drizzle-Turbulence Interactions in Boundary Layer Clouds

    DTIC Science & Technology

    2012-09-30

    provide a means for evaluating and developing parameterizations for models that predict cloud microphysical processes. Observations of the...observed during BACEX was associated with African dust above the boundary layer. On two days when convection was completely suppressed, an African... dust event associated with record Aerosol Optical Depths (AODs) for Barbados during this time of the year was observed. The vertical structure of the

  15. Ground based in situ measurements of arctic cloud microphysical and optical properties at Mount Zeppelin (Ny-Alesund Svalbard)

    NASA Astrophysics Data System (ADS)

    Guyot, Gwennolé; Jourdan, Olivier; Olofson, Frans; Schwarzenboeck, Alfons; Gourbeyre, Christophe; Febvre, Guy; Dupuy, Régis; Bernard, Christophe; Tunved, Peter; Ancellet, Gérard; Law, Kathy; Wobrock, Wolfram; Shcherbakov, Valery

    2015-04-01

    whereas blowing snow is typically composed of 250 µm irregular ice crystals. This dataset will be used to test physically based representations of the relationships between particle size, shape and optical properties and to investigate dominant microphysical processes occurring in MPC using detailed microphysical modeling. Moreover, carbon monoxide measurements allow us to compare polluted with clean cases. The cloud-aerosol interactions processes which take place during the transport of polluted air masses from mid-latitude to the Arctic is thus assessed.

  16. Cloud microphysical background for the Israel-4 cloud seeding experiment

    NASA Astrophysics Data System (ADS)

    Freud, Eyal; Koussevitzky, Hagai; Goren, Tom; Rosenfeld, Daniel

    2015-05-01

    The modest amount of rainfall in Israel occurs in winter storms that bring convective clouds from the Mediterranean Sea when the cold post frontal air interacts with its relatively warm surface. These clouds were seeded in the Israel-1 and Israel-2 cloud glaciogenic seeding experiments, which have shown statistically significant positive effect of added rainfall of at least 13% in northern Israel, whereas the Israel-3 experiment showed no added rainfall in the south. This was followed by operational seeding in the north since 1975. The lack of physical evidence for the causes of the positive effects in the north caused a lack of confidence in the statistical results and led to the Israel-4 randomized seeding experiment in northern Israel. This experiment started in the winter of 2013/14. The main difference from the previous experiments is the focus on the orographic clouds in the catchment of the Sea of Galilee. The decision to commence the experiment was partially based on evidence supporting the existence of seeding potential, which is reported here. Aircraft and satellite microphysical and dynamic measurements of the clouds document the critical roles of aerosols, especially sea spray, on cloud microstructure and precipitation forming processes. It was found that the convective clouds over sea and coastal areas are naturally seeded hygroscopically by sea spray and develop precipitation efficiently. The diminution of the large sea spray aerosols farther inland along with the increase in aerosol concentrations causes the clouds to develop precipitation more slowly. The short time available for the precipitation forming processes in super-cooled orographic clouds over the Golan Heights farthest inland represents the best glaciogenic seeding potential.

  17. Microphysical characterization of winter cloud systems during a research flight campaign

    NASA Astrophysics Data System (ADS)

    Fernández-González, Sergio; Sánchez, José Luis; Valero, Francisco; Gascón, Estíbaliz; Merino, Andrés; Hermida, Lucía; López, Laura; Marcos, José Luis; García-Ortega, Eduardo

    2015-04-01

    The lack of accuracy in the knowledge of cloud microphysics leads to aviation risks, which have caused numerous crashes, mainly owing to aircraft icing (e.g., an EMB-120 crashed in Detroit, Michigan in 1997, and an ATR-72 crashed near Roselawn, Indiana in 1994). Further, this lack is a source of uncertainty in numerical weather forecasting models, since commonly used parameterizations often overestimate ice water content and underestimate supercooled liquid water. This makes the collection of data on cloud microphysical characteristics very useful toward improving the forecasting of icing conditions. Ten research flights were conducted during the winters of 2011/12 and 2012/13. Their goal was to determine dominant microphysical conditions of winter cloud systems traversing the Guadarrama Mountains in the central Iberian Peninsula. The aircraft was a C-212-200, equipped with a Cloud, Aerosol, and Precipitation Spectrometer (CAPS) under the left wing. Data of temperature and Liquid Water Content (LWC), registered by the CAPS probe, were used in the study. Furthermore, we thoroughly analyzed images taken by a Cloud Imaging Probe Grayscale (CIP-GS), capable of measuring hydrometeors between 25 and 1,550 µm in size, and representing them in a 2D image. The various types of hydrometeors observed during these flights are described, along with microphysical processes inferred from the CIP-GS images. ACKNOWLEDGEMENTS S. Fernández-González acknowledges grant support from the FPU program (AP 2010-2093). This study was also supported by grants from GRANIMETRO (CGL2010-15930) and MICROMETEO (IPT-310000-2010-22). The authors thank INTA for the research flights.

  18. Aerosol-Cloud Interactions in the South-East Atlantic

    NASA Astrophysics Data System (ADS)

    Andersen, Hendrik; Cermak, Jan

    2014-05-01

    In this contribution, a satellite-based study on aerosol-cloud interactions (ACI) in the South-East Atlantic with explicit consideration of meteorological conditions is presented. Aerosol-Cloud Interactions remain difficult to quantify and contribute the largest uncertainty to global radiative forcing. These uncertainties make them one of the most important factors for anthropogenic climate perturbations. Interactions are highly complex as microphysical and macrostructural cloud adjustments to aerosol perturbations do not transpire in a black box but are highly dependent on a variety of factors like cloud regime, meteorology and aerosol properties. To gain understanding of the processes that govern ACI in order to increase accuracy of climate models and predictions of future changes in the climate system is thus of great importance. This process study uses multiple statistical approaches to untangle the various influences on ACI. Stratocumulus clouds in the South-East Atlantic are investigated over a time span of 10 years using daily Terra MODIS L3 data for aerosol and cloud parameters. Together with ERA-Interim reanalysis data of cloud-relevant meteorological parameters, statistical relationships between aerosol and cloud properties are derived for different weather types on the basis of a kmeans cluster analysis, in addition to bivariate relationships. Also, the influence of aerosol loading on aerosol-cloud relationships is investigated. Relationships between aerosol and cloud microphysical properties are established. Macrostructural cloud adjustments are more ambiguous, as the observed positive relationship between aerosol and cloud liquid water path (LWP) is inconsistent with the Albrecht hypothesis (more cloud water due to drizzle suppression). Adjustments of cloud optical thickness (COT) to aerosol perturbations are negligible as COT is highly dependent on LWP. Strong relationships between aerosol and cloud fraction are identified, but might be spurious and

  19. 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

  20. 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.

  1. The global atmospheric electric circuit and its effects on cloud microphysics

    NASA Astrophysics Data System (ADS)

    Tinsley, B. A.

    2008-06-01

    variations. The theory for electrical effects on scavenging of aerosols in clouds is reviewed, with several microphysical processes having consequences for contact ice nucleation; effects on droplet size distributions; precipitation and cloud lifetimes. There are several pathways for resulting macroscopic cloud changes that affect atmospheric circulation; including enhanced ice production and precipitation from clouds in cyclonic storms, with latent heat release affecting cyclone vorticity; and cloud cover changes in layer clouds that affect the atmospheric radiation balance. These macroscopic consequences of global circuit variability affecting aerosols-cloud interactions provide explanations for the many observations of short term and long term changes in clouds and climate that correlate with measured or inferred Jz and cosmic ray flux changes due to external or internal forcing, and lead to predictions of additional effects.

  2. AEROSOL, CLOUDS, AND CLIMATE CHANGE

    SciTech Connect

    SCHWARTZ, S.E.

    2005-09-01

    Earth's climate is thought to be quite sensitive to changes in radiative fluxes that are quite small in absolute magnitude, a few watts per square meter, and in relation to these fluxes in the natural climate. Atmospheric aerosol particles exert influence on climate directly, by scattering and absorbing radiation, and indirectly by modifying the microphysical properties of clouds and in turn their radiative effects and hydrology. The forcing of climate change by these indirect effects is thought to be quite substantial relative to forcing by incremental concentrations of greenhouse gases, but highly uncertain. Quantification of aerosol indirect forcing by satellite- or ground-based remote sensing has proved quite difficult in view of inherent large variation in the pertinent observables such as cloud optical depth, which is controlled mainly by liquid water path and only secondarily by aerosols. Limited work has shown instances of large magnitude of aerosol indirect forcing, with local instantaneous forcing upwards of 50 W m{sup 66}-2. Ultimately it will be necessary to represent aerosol indirect effects in climate models to accurately identify the anthropogenic forcing at present and over secular time and to assess the influence of this forcing in the context of other forcings of climate change. While the elements of aerosol processes that must be represented in models describing the evolution and properties of aerosol particles that serve as cloud condensation particles are known, many important components of these processes remain to be understood and to be represented in models, and the models evaluated against observation, before such model-based representations can confidently be used to represent aerosol indirect effects in climate models.

  3. 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.

  4. Aerosol particles and the formation of advection fog

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Liaw, G. S.; Vaughan, O. H., Jr.

    1979-01-01

    A study of numerical simulation of the effects of concentration, particle size, mass of nuclei, and chemical composition on the dynamics of warm fog formation, particularly the formation of advection fog, is presented. This formation is associated with the aerosol particle characteristics, and both macrophysical and microphysical processes are considered. In the macrophysical model, the evolution of wind components, water vapor content, liquid water content, and potential temperature under the influences of vertical turbulent diffusion, turbulent momentum, and turbulent energy transfers are taken into account. In the microphysical model, the supersaturation effect is incorporated with the surface tension and hygroscopic material solution. It is shown that the aerosol particles with the higher number density, larger size nuclei, the heavier nuclei mass, and the higher ratio of the Van't Hoff factor to the molecular weight favor the formation of the lower visibility advection fogs with stronger vertical energy transfer during the nucleation and condensation time period.

  5. Air pollution radiative and microphysical impacts on rainfall

    NASA Astrophysics Data System (ADS)

    Rosenfeld, D.

    2008-12-01

    Aerosols affect rainfall in various ways: The microphysical effects slow the conversion of cloud drop to hydrometeors. In shallow clouds it means suppression of precipitation. In deep clouds with warm base the delay of precipitation to heights where freezing can occur this leads to invigoration of the clouds due to the added latent heat release of freezing. When the aerosol load becomes heavy the radiative effects of suppressing surface heating can decrease the convection. In addition, delaying the onset of precipitation to great heights leads to greater evaporation of smaller precipitation efficiency due to more evaporation of cloud water and hydrometeors. An example of the impacts of heavy air pollution is available for China. Time series of rainfall, thunderstorms, temperatures, winds and aerosols for the period of 1953-2005 have been analyzed at the Xian valley and the nearby Mount Hua in central China, for assessing the impact of the increasing air pollution thunderstorms on convective precipitation. Adding aerosols to pristine air initially increases convective rainfall. However, aerosol amounts have been shown to be sufficiently high so that added aerosols suppress convection and precipitation, by both radiative and microphysical effects, even at the starting of the analysis period at the 1950's. It was found that the aerosols negative radiative forcing stabilized the lowest troposphere by about 1°C. The stabilization resulted in less vertical exchanges of air, which caused reduction in the lowland surface winds and increase in the mountain top wind speeds. The decreased instability caused a decrease in the frequency of the thunderstorm normalized by rainfall amount in the lowland due to the thick aerosol layer above, but not at the mountaintop, above which the aerosol layer was much thinner. The indicated decreasing trend of mountain precipitation was associated with a similar size decreasing trend in thunderstorm frequency. This decrease was contributed

  6. Development of Two-Moment Cloud Microphysics for Liquid and Ice Within the NASA Goddard Earth Observing System Model (GEOS-5)

    NASA Technical Reports Server (NTRS)

    Barahona, Donifan; Molod, Andrea M.; Bacmeister, Julio; Nenes, Athanasios; Gettelman, Andrew; Morrison, Hugh; Phillips, Vaughan,; Eichmann, Andrew F.

    2013-01-01

    . However significant sensitivity in ice cloud properties was found to variation in the dispersion of the ice crystal size distribution and the critical size for ice autoconversion. The implementation of the new microphysics leads to a more realistic representation of cloud processes in GEOS-5 and allows the linkage of cloud properties to aerosol emissions.

  7. Clouds, aerosols, and photochemistry in the Jovian atmosphere

    NASA Technical Reports Server (NTRS)

    West, R. A.; Strobel, D. F.; Tomasko, M. G.

    1986-01-01

    An assessment is made of the development status of concepts for cloud and aerosol compositions, vertical and horizontal distributions, and microphysical properties, in the Jovian upper troposphere and stratosphere. Attention is given to several key photochemical species' relationships to aerosol formation as well as their transport process implications, treating photochemistry in the context of comparative planetology and noting differences and similarities among the outer planet atmospheres; since this approach emphasizes observational data, a variegated assortment of ground-based and spacecraft observations is assembled. Current views on the tropospheric distribution of clouds are challenged, and a rationale is presented for alternative accounts.

  8. Clouds, aerosols, and photochemistry in the Jovian atmosphere

    NASA Astrophysics Data System (ADS)

    West, R. A.; Strobel, D. F.; Tomasko, M. G.

    1986-03-01

    An assessment is made of the development status of concepts for cloud and aerosol compositions, vertical and horizontal distributions, and microphysical properties, in the Jovian upper troposphere and stratosphere. Attention is given to several key photochemical species' relationships to aerosol formation as well as their transport process implications, treating photochemistry in the context of comparative planetology and noting differences and similarities among the outer planet atmospheres; since this approach emphasizes observational data, a variegated assortment of ground-based and spacecraft observations is assembled. Current views on the tropospheric distribution of clouds are challenged, and a rationale is presented for alternative accounts.

  9. Radiative Effects of Aerosols

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.

    1997-01-01

    During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size resolved aerosol microphysics and chemistry. Both profiles included pollution haze layer from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core.

  10. Regime Dependant Microphysical Variability in Darwin, Australia

    NASA Astrophysics Data System (ADS)

    Dolan, B.; Rutledge, S. A.; Lang, T. J.

    2010-12-01

    Of utmost importance for global precipitation estimates from satellites such as TRMM and the upcoming Global Precipitation Measurement (GPM) is to understand processes that lead to variability in precipitation on sub-seasonal, seasonal, and climatological scales. Many studies have linked differences in rainfall characteristics such as mean diameter (D0) to sub-seasonal regime variability forced by large scale wind shifts, topography, and continental and maritime convection, across various regions of the globe. Several analyses have tied differences between regimes to differing microphysical processes that drive changes in the drop-size distributions occurring in convective rainfall. For example, decreased ice mass aloft and smaller mean diameters are indicative of warm rain processes, while vigorous ice formation leads to large, melting ice to create large drops. If the microphysical variability in different regimes is characterized and understood, the results could be used to improve satellite precipitation algorithms. The polarimetric, Doppler C-band radar, CPOL, located near Darwin, Australia provides a unique platform to study differences in microphysics between land and ocean, as well as variability between monsoon and break periods. The focus of this study is to examine the microphysical processes occurring in four distinct regimes around Darwin (monsoon-land, monsoon-ocean, break-land, break-ocean), using polarimetric data from CPOL. Analyses such as contoured frequency by altitude (CFADs) diagrams, cumulative distribution functions, and mean profiles of precipitation water mass, precipitation ice mass, reflectivity, differential reflectivity and specific differential phase will aide in understanding the physics of precipitation in these regimes. The formation of precipitation ice aloft, warm rain processes, and the contributions of warm rain and cold cloud processes including melting of ice into large drops, will be linked to differences in D0, rain

  11. Process evaluation of sea salt aerosol concentrations at remote marine locations

    NASA Astrophysics Data System (ADS)

    Struthers, H.; Ekman, A. M.; Nilsson, E. D.

    2011-12-01

    Sea salt, an important natural aerosol, is generated by bubbles bursting at the surface of the ocean. Sea salt aerosol contributes significantly to the global aerosol burden and radiative budget and are a significant source of cloud condensation nuclei in remote marine areas (Monahan et al., 1986). Consequently, changes in marine aerosol abundance is expected to impact on climate forcing. Estimates of the atmospheric burden of sea salt aerosol mass derived from chemical transport and global climate models vary greatly both in the global total and the spatial distribution (Texor et al. 2006). This large uncertainty in the sea salt aerosol distribution in turn contributes to the large uncertainty in the current estimates of anthropogenic aerosol climate forcing (IPCC, 2007). To correctly attribute anthropogenic climate change and to veraciously project future climate, natural aerosols including sea salt must be understood and accurately modelled. In addition, the physical processes that determine the sea salt aerosol concentration are susceptible to modification due to climate change (Carslaw et al., 2010) which means there is the potential for feedbacks within the climate/aerosol system. Given the large uncertainties in sea salt aerosol modelling, there is an urgent need to evaluate the process description of sea salt aerosols in global models. An extremely valuable source of data for model evaluation is the long term measurements of PM10 sea salt aerosol mass available from a number of remote marine observation sites around the globe (including the GAW network). Sea salt aerosol concentrations at remote marine locations depend strongly on the surface exchange (emission and deposition) as well as entrainment or detrainment to the free troposphere. This suggests that the key parameters to consider in any analysis include the sea surface water temperature, wind speed, precipitation rate and the atmospheric stability. In this study, the sea salt aerosol observations

  12. 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.

  13. Laboratory Studies of Processing of Carbonaceous Aerosols by Atmospheric Oxidants/Hygroscopicity and CCN Activity of Secondary & Processed Primary Organic Aerosols

    SciTech Connect

    Ziemann, P.J.; Arey, J.; Atkinson, R.; Kreidenweis, S.M.; Petters, M.D.

    2012-06-13

    The atmosphere is composed of a complex mixture of gases and suspended microscopic aerosol particles. The ability of these particles to take up water (hygroscopicity) and to act as nuclei for cloud droplet formation significantly impacts aerosol light scattering and absorption, and cloud formation, thereby influencing air quality, visibility, and climate in important ways. A substantial, yet poorly characterized component of the atmospheric aerosol is organic matter. Its major sources are direct emissions from combustion processes, which are referred to as primary organic aerosol (POA), or in situ processes in which volatile organic compounds (VOCs) are oxidized in the atmosphere to low volatility reaction products that subsequent condense to form particles that are referred to as secondary organic aerosol (SOA). POA and VOCs are emitted to the atmosphere from both anthropogenic and natural (biogenic) sources. The overall goal of this experimental research project was to conduct laboratory studies under simulated atmospheric conditions to investigate the effects of the chemical composition of organic aerosol particles on their hygroscopicity and cloud condensation nucleation (CCN) activity, in order to develop quantitative relationships that could be used to more accurately incorporate aerosol-cloud interactions into regional and global atmospheric models. More specifically, the project aimed to determine the products, mechanisms, and rates of chemical reactions involved in the processing of organic aerosol particles by atmospheric oxidants and to investigate the relationships between the chemical composition of organic particles (as represented by molecule sizes and the specific functional groups that are present) and the hygroscopicity and CCN activity of oxidized POA and SOA formed from the oxidation of the major classes of anthropogenic and biogenic VOCs that are emitted to the atmosphere, as well as model hydrocarbons. The general approach for this project was

  14. 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.

  15. Potential impact of dust aerosols on the pre-Helene (2006) mesoscale convective vortex

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Sokolik, I. N.; Curry, J. A.

    2011-12-01

    The potential impact of dust aerosols on the early development of Hurricane Helene (2006) was examined using the Weather Research and Forecasting (WRF) and WRF-Chem model. The goal of this study is to examine the extent to which dust aerosols can influence the intensity, track, and structure of a developing TC through the microphysical and radiation processes. Remote sensing observations from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), CloudSat, Moderate Resolution Imaging Spectroradiometer (MODIS), and Tropical Rainfall Measuring Mission (TRMM) were utilized to examine the distributions and characteristics of dust particles, hydrometeors, cloud top temperature, latent heat release and precipitation, as well as to constrain and evaluate the model simulations. The WRF simulations were conducted by implementing an ice nucleation parameterization accounting for the deliquescent heterogeneous freezing (DHF) mode. The DHF mode refers to the freezing process for internally mixed aerosols with soluble and insoluble species that can serve as both cloud condensation nuclei (CCN) and ice nuclei (IN), such as dust. Simulations showed the tendency of DHF mode to promote ice formation at lower altitudes in strong updraft cores, increase the local latent heat release, and produce more low clouds and less high clouds. Further more, a series of WRF-Chem simulations were conducted, which includes aerosol emission scheme, a radiative transfer scheme accounting for aerosol optical properties, and a dual moment microphysics scheme that will account for environmental aerosols as nuclei. Differences between the results from WRF and WRF-Chem simulations were examined.

  16. Microphysical/mesoscale aspects of nuclear winter and new directions in assessments

    SciTech Connect

    Knox, J.B.

    1985-06-01

    Recent results of model studies and sensitivity tests have shown the degree to which the intensity and duration of ''nuclear winter'' depends on the mass of soot and dust suspended, its optical properties, its vertical distribution in the atmosphere, and the residence time. The soot from urban fires is viewed as evolving during its dispersion from the early fire induced plumes, to cloud scale systems, to the mesoscale and larger systems. Micro-physical processes are perceived as operating within these systems in a manner to enhance removal from the troposphere, and to alter the verical distribution of the soot or its subsequent, aging or evolving aerosol. Relevant observations and studies of these processes are presented and discussed. Critical inputs to the climate simulation models may well be altered significantly by these process effects, many of which are in need of better definition. Appropriate research needs to be initiated to address and better define these microphysical/mesoscale processes of potential importance in the altered atmospheric system after a major nuclear exchange. 11 refs., 2 figs.

  17. 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.

  18. Super-droplet method as a versatile numerical approach for representing aerosol-cloud-aerosol interactions.

    NASA Astrophysics Data System (ADS)

    Jaruga, Anna; Arabas, Sylwester; Pawlowska, Hanna

    2013-04-01

    Aerosol interacts with clouds by serving as cloud condensation nuclei (CCN). Its physical and chemical properties are one of the factors defining cloud droplet size distribution. On the other hand, clouds process atmospheric aerosol taking part in its wet deposition and CCN regeneration through evaporation of cloud droplets and drizzle. Physical and chemical properties of the regenerated CCN may be altered if the evaporated droplets go through collisional growth or irreversible chemical reactions. The main challenge of representing these aerosol-cloud interactions in a numerical cloud model stems from the need to track the properties of the drop nuclei throughout the cloud lifecycle. A class of methods allowing such studies is the Lagrangian particle-based simulation technique. In a simulation of cloud, each modeled particle represents a multiplicity of particles of the same nucleus type, position and size. During the simulation particle sizes change in a continuous way from CCN-sized to rain drop particles. Tracking microphysical properties of modeled particles is an inherent feature of the particle-based frameworks, making them suitable for studying aerosol-cloud-aerosol interactions. Super-droplet method is a Lagrangian technique introduced by Shima et al. (2009) featuring an efficient Monte-Carlo type solver for particle coalescence. In this study a new implementation of the super-droplet method, using the kappa-Koehler parametrisation of aerosol composition and an aqueous chemistry module for representing irreversible oxidation, will be presented. Components of the developed model will be discussed using a single-eddy prescribed-flow framework, focusing solely on the microphysical aspects of simulations. Example case will mimic a Stratocumulus cloud and depict cloud-aerosol interactions resolved by the model.

  19. Photolytic processing of secondary organic aerosols dissolved in cloud droplets.

    PubMed

    Bateman, Adam P; Nizkorodov, Sergey A; Laskin, Julia; Laskin, Alexander

    2011-07-14

    The effect of UV irradiation on the molecular composition of aqueous extracts of secondary organic aerosol (SOA) was investigated. SOA was prepared by the dark reaction of ozone and d-limonene at 0.05-1 ppm precursor concentrations and collected with a particle-into-liquid sampler (PILS). The PILS extracts were photolyzed by 300-400 nm radiation for up to 24 h. Water-soluble SOA constituents were analyzed using high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) at different stages of photolysis for all SOA precursor concentrations. Exposure to UV radiation increased the average O/C ratio and decreased the average double bond equivalent (DBE) of the dissolved SOA compounds. Oligomeric compounds were significantly decreased by photolysis relative to the monomeric compounds. Direct pH measurements showed that acidic compounds increased in abundance upon photolysis. Methanol reactivity analysis revealed significant photodissociation of molecules containing carbonyl groups and the formation of carboxylic acids. Aldehydes, such as limononaldehyde, were almost completely removed. The removal of carbonyls was further confirmed by the UV/Vis absorption spectroscopy of the SOA extracts where the absorbance in the carbonyl n→π* band decreased significantly upon photolysis. The effective quantum yield (the number of carbonyls destroyed per photon absorbed) was estimated as ∼0.03. The total concentration of peroxides did not change significantly during photolysis as quantified with an iodometric test. Although organic peroxides were photolyzed, the likely end products of photolysis were smaller peroxides, including hydrogen peroxide, resulting in a no net change in the peroxide content. Photolysis of dry limonene SOA deposited on substrates was investigated in a separate set of experiments. The observed effects on the average O/C and DBE were similar to the aqueous photolysis, but the extent of chemical change was smaller in dry SOA. Our results suggest

  20. Impacts of aerosol-monsoon interaction on rainfall and circulation over Northern India and the Himalaya Foothills

    NASA Astrophysics Data System (ADS)

    Lau, William K. M.; Kim, Kyu-Myong; Shi, Jainn-Jong; Matsui, T.; Chin, M.; Tan, Qian; Peters-Lidard, C.; Tao, W. K.

    2016-11-01

    The boreal summer of 2008 was unusual for the Indian monsoon, featuring exceptional heavy loading of dust aerosols over the Arabian Sea and northern-central India, near normal all-India rainfall, but excessive heavy rain, causing disastrous flooding in the Northern Indian Himalaya Foothills (NIHF) regions, accompanied by persistent drought conditions in central and southern India. Using the NASA Unified-physics Weather Research Forecast (NUWRF) model with fully interactive aerosol physics and dynamics, we carried out three sets of 7-day ensemble model forecast experiments: (1) control with no aerosol, (2) aerosol radiative effect only and (3) aerosol radiative and aerosol-cloud-microphysics effects, to study the impacts of aerosol-monsoon interactions on monsoon variability over the NIHF during the summer of 2008. Results show that aerosol-radiation interaction (ARI), i.e., dust aerosol transport, and dynamical feedback processes induced by aerosol-radiative heating, plays a key role in altering the large-scale monsoon circulation system, reflected by an increased north-south tropospheric temperature gradient, a northward shift of heavy monsoon rainfall, advancing the monsoon onset by 1-5 days over the HF, consistent with the EHP hypothesis (Lau et al. in Clim Dyn 26(7-8):855-864, 2006). Additionally, we found that dust aerosols, via the semi-direct effect, increase atmospheric stability, and cause the dissipation of a developing monsoon onset cyclone over northeastern India/northern Bay of Bengal. Eventually, in a matter of several days, ARI transforms the developing monsoon cyclone into meso-scale convective cells along the HF slopes. Aerosol-Cloud-microphysics Interaction (ACI) further enhances the ARI effect in invigorating the deep convection cells and speeding up the transformation processes. Results indicate that even in short-term (up to weekly) numerical forecasting of monsoon circulation and rainfall, effects of aerosol-monsoon interaction can be

  1. Impact of Local Pollution Versus Long Range Transported Aerosols on Clouds and Precipitation over California

    NASA Astrophysics Data System (ADS)

    Prather, K. A.

    2015-12-01

    Aerosols form cloud droplets and ice crystals in clouds and can profoundly impact precipitation processes. In-situ aircraft measurements of the composition of individual cloud residuals have been used to study the impact of different aerosol sources including sea spray, dust, soot, and biomass burning on cloud microphysics and precipitation processes. Aircraft studies in 2011 as part of the CalWater project showed that long range transport of dust aerosols from as far away as Africa and biological particles can lead to an increase in the amount of snowfall over California. This presentation will describe results from CalWater-2015 involving aircraft and ground-based measurements at a coastal site. A discussion of the aerosol sources measured in clouds will be presented detailing the relative impacts of local versus long range transported pollution aerosols over California.

  2. Influences from soluble and insoluble aerosols on precipitation and lightning in deep convection

    NASA Astrophysics Data System (ADS)

    Phillips, Vaughan; Formenton, Marco; Lienert, Barry

    2013-04-01

    Observations reported in past studies in the literature have revealed correlations between measures of aerosol loading and lightning occurrence. Recent advances in simulating cloud-microphysical processes have highlighted their control by aerosol conditions. New hypotheses about aerosol-precipitation-lightning interactions have emerged. Most deep convective clouds globally have warm bases with precipitation controlled by coalescence and by loadings of soluble aerosols, which form droplets. However, those over mountainous continental regions often have cooler bases and can generate much hail that reaches the ground. Cold-base convective clouds were observed to produce lightning over the High Plains of the USA during the Severe Thunderstorms Electrification and Precipitation Study (STEPS) in the summer of 2000. Cold-base thunderstorms can be without an active coalescence process, due to the low adiabatic liquid water content limiting droplet sizes. There is then the potential for a greater influence from ice-nucleating insoluble aerosols on ice-precipitation production, charge separation and lightning, relative to soluble aerosols. In the presentation, an aerosol-cloud model (hybrid bin/2-moment bulk microphysics, prognostic aerosol component with 6 aerosol species) with a new electrification component is described. The model treats non-inductive charge separation and has a lightning discharge scheme. A simulation of a STEPS case of a cold-base thunderstorm is validated against aircraft, radar and electrical observations. Sensitivity tests are presented to show the roles of ice multiplication and ice-nucleating aerosols, such as dust and soot from biomass-burning plumes, in controlling ice-precipitation production and lightning frequencies for the cold-base thunderstorm. Their influence is compared with that from soluble aerosol loadings. The roles of cloud-base temperature and wet growth of hail and graupel are discussed.

  3. New approaches to quantifying aerosol influence on the cloud radiative effect.

    PubMed

    Feingold, Graham; McComiskey, Allison; Yamaguchi, Takanobu; Johnson, Jill S; Carslaw, Kenneth S; Schmidt, K Sebastian

    2016-05-24

    The topic of cloud radiative forcing associated with the atmospheric aerosol has been the focus of intense scrutiny for decades. The enormity of the problem is reflected in the need to understand aspects such as aerosol composition, optical properties, cloud condensation, and ice nucleation potential, along with the global distribution of these properties, controlled by emissions, transport, transformation, and sinks. Equally daunting is that clouds themselves are complex, turbulent, microphysical entities and, by their very nature, ephemeral and hard to predict. Atmospheric general circulation models represent aerosol-cloud interactions at ever-increasing levels of detail, but these models lack the resolution to represent clouds and aerosol-cloud interactions adequately. There is a dearth of observational constraints on aerosol-cloud interactions. We develop a conceptual approach to systematically constrain the aerosol-cloud radiative effect in shallow clouds through a combination of routine process modeling and satellite and surface-based shortwave radiation measurements. We heed the call to merge Darwinian and Newtonian strategies by balancing microphysical detail with scaling and emergent properties of the aerosol-cloud radiation system.

  4. New approaches to quantifying aerosol influence on the cloud radiative effect

    NASA Astrophysics Data System (ADS)

    Feingold, Graham; McComiskey, Allison; Yamaguchi, Takanobu; Johnson, Jill S.; Carslaw, Kenneth S.; Schmidt, K. Sebastian

    2016-05-01

    The topic of cloud radiative forcing associated with the atmospheric aerosol has been the focus of intense scrutiny for decades. The enormity of the problem is reflected in the need to understand aspects such as aerosol composition, optical properties, cloud condensation, and ice nucleation potential, along with the global distribution of these properties, controlled by emissions, transport, transformation, and sinks. Equally daunting is that clouds themselves are complex, turbulent, microphysical entities and, by their very nature, ephemeral and hard to predict. Atmospheric general circulation models represent aerosol-cloud interactions at ever-increasing levels of detail, but these models lack the resolution to represent clouds and aerosol-cloud interactions adequately. There is a dearth of observational constraints on aerosol-cloud interactions. We develop a conceptual approach to systematically constrain the aerosol-cloud radiative effect in shallow clouds through a combination of routine process modeling and satellite and surface-based shortwave radiation measurements. We heed the call to merge Darwinian and Newtonian strategies by balancing microphysical detail with scaling and emergent properties of the aerosol-cloud radiation system.

  5. New approaches to quantifying aerosol influence on the cloud radiative effect

    DOE PAGES

    Feingold, Graham; McComiskey, Allison; Yamaguchi, Takanobu; ...

    2016-02-01

    The topic of cloud radiative forcing associated with the atmospheric aerosol has been the focus of intense scrutiny for decades. The enormity of the problem is reflected in the need to understand aspects such as aerosol composition, optical properties, cloud condensation, and ice nucleation potential, along with the global distribution of these properties, controlled by emissions, transport, transformation, and sinks. Equally daunting is that clouds themselves are complex, turbulent, microphysical entities and, by their very nature, ephemeral and hard to predict. Atmospheric general circulation models represent aerosol-cloud interactions at ever-increasing levels of detail, but these models lack the resolution tomore » represent clouds and aerosol-cloud interactions adequately. There is a dearth of observational constraints on aerosol-cloud interactions. We develop a conceptual approach to systematically constrain the aerosol-cloud radiative effect in shallow clouds through a combination of routine process modeling and satellite and surface-based shortwave radiation measurements. We heed the call to merge Darwinian and Newtonian strategies by balancing microphysical detail with scaling and emergent properties of the aerosol-cloud radiation system.« less

  6. Aerosol physicochemical properties in relation to meteorology: Case studies in urban, marine, and arid settings

    NASA Astrophysics Data System (ADS)

    Wonaschuetz, Anna

    Atmospheric aerosols are a highly relevant component of the climate system affecting atmospheric radiative transfer and the hydrological cycle. As opposed to other key atmospheric constituents with climatic relevance, atmospheric aerosol particles are highly heterogeneous in time and space with respect to their size, concentration, chemical composition and physical properties. Many aspects of their life cycle are not understood, making them difficult to represent in climate models and hard to control as a pollutant. Aerosol-cloud interactions in particular are infamous as a major source of uncertainty in future climate predictions. Field measurements are an important source of information for the modeling community and can lead to a better understanding of chemical and microphysical processes. In this study, field data from urban, marine, and arid settings are analyzed and the impact of meteorological conditions on the evolution of aerosol particles while in the atmosphere is investigated. Particular attention is given to organic aerosols, which are a poorly understood component of atmospheric aerosols. Local wind characteristics, solar radiation, relative humidity and the presence or absence of clouds and fog are found to be crucial factors in the transport and chemical evolution of aerosol particles. Organic aerosols in particular are found to be heavily impacted by processes in the liquid phase (cloud droplets and aerosol water). The reported measurements serve to improve the process-level understanding of aerosol evolution in different environments and to inform the modeling community by providing realistic values for input parameters and validation of model calculations.

  7. Investigation of multiple scattering effects in aerosols

    NASA Technical Reports Server (NTRS)

    Deepak, A.

    1980-01-01

    The results are presented of investigations on the various aspects of multiple scattering effects on visible and infrared laser beams transversing dense fog oil aerosols contained in a chamber (4' x 4' x 9'). The report briefly describes: (1) the experimental details and measurements; (2) analytical representation of the aerosol size distribution data by two analytical models (the regularized power law distribution and the inverse modified gamma distribution); (3) retrieval of aerosol size distributions from multispectral optical depth measurements by two methods (the two and three parameter fast table search methods and the nonlinear least squares method); (4) modeling of the effects of aerosol microphysical (coagulation and evaporation) and dynamical processes (gravitational settling) on the temporal behavior of aerosol size distribution, and hence on the extinction of four laser beams with wavelengths 0.44, 0.6328, 1.15, and 3.39 micrometers; and (5) the exact and approximate formulations for four methods for computing the effects of multiple scattering on the transmittance of laser beams in dense aerosols, all of which are based on the solution of the radiative transfer equation under the small angle approximation.

  8. Enhanced water vapor in Asian dust layer: Entrainment processes and implication for aerosol optical properties

    NASA Astrophysics Data System (ADS)

    Yoon, Soon-Chang; Kim, Sang-Woo; Kim, Jiyoung; Sohn, Byung-Ju; Jefferson, Anne; Choi, Suk-Jin; Cha, Dong-Hyun; Lee, Dong-Kyou; Anderson, Theodore L.; Doherty, Sarah J.; Weber, Rodney J.

    The entrainment process of water vapor into the dust layer during Asian dust events and the effect of water vapor associated with the Asian dust layer (ADL) on aerosol hygroscopic properties are investigated. The entrainment processes of water vapor into the ADL is examined by using a PSU/NCAR MM5 together with the backward trajectory model, radiosonde data, and remotely sensed aerosol vertical distribution data. Two dust events in the spring of 1998 and 2001 are examined in detail. The results reveal that the water vapor mixing ratio (WVMR) derived by the MM5 fits in well with the WVMR observed by radiosonde, and is well coincident with the aerosol extinction coefficient ( σep) measured by the micro-pulse lidar. The temporal evolution of the vertical distributions of WVMR and σep exhibited similar features. On the basis of a well simulation of the enhanced water vapor within the dust layer by the MM5, we trace the dust storms to examine the entrainment mechanism. The enhancement of WVMR within the ADL was initiated over the mountainous areas. The relatively moist air mass in the well-developed mixing layer over the mountainous areas is advected upward from the boundary layer by an ascending motion. However, a large portion of the water vapor within the ADL is enhanced over the edge of a highland and the plains in China. This is well supported by the simulated WVMR and the wind vectors. Aircraft-based in situ measurements of the chemical and optical properties of aerosol enable a quantitative estimation of the effect of the enhanced WVMR on the aerosol hygroscopic properties. The submicron aerosol accompanied by the dust storm caused an increase of aerosol scattering through water uptakes during the transport. This increase could be explained by the chemical fact that water-soluble submicron pollution aerosols are enriched in the ADL.

  9. 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

  10. Sensitivity of depositions to the size and hygroscopicity of Cs-bearing aerosols released from the Fukushima nuclear accident

    NASA Astrophysics Data System (ADS)

    Kajino, Mizuo; Adachi, Kouji; Sekiyama, Tsuyoshi; Zaizen, Yuji; Igarashi, Yasuhito

    2014-05-01

    We recently revealed that the microphysical properties of aerosols carrying the radioactive Cs released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) at an early stage (March 14-15, 2011) of the accident could be very different from what we assumed previously: super-micron and non-hygroscopic at the early stage, whereas sub-micron and hygroscopic afterwards (at least later than March 20-22). In the study, two sensitivity simulations with the two different aerosol microphysical properties were conducted using a regional scale meteorology- chemical transport model (NHM-Chem). The impact of the difference was quite significant. 17% (0.001%) of the radioactive Cs fell onto the ground by dry (wet) deposition processes, and the rest was deposited into the ocean or was transported out of the model domain, which is central and northern part of the main land of Japan, under the assumption that Cs-bearing aerosols are non-hygroscopic and super-micron. On the other hand, 5.7% (11.3%) fell onto the ground by dry (wet) deposition, for the cases under the assumption that the Cs-bearing aerosols are hygroscopic and sub-micron. For the accurate simulation of the deposition of radionuclides, knowledge of the aerosol microphysical properties is essential as well as the accuracy of the simulated wind fields and precipitation patterns.

  11. Combined observational and modeling efforts of aerosol-cloud-precipitation interactions over Southeast Asia

    NASA Astrophysics Data System (ADS)

    Loftus, Adrian; Tsay, Si-Chee; Nguyen, Xuan Anh

    2016-04-01

    Low-level stratocumulus (Sc) clouds cover more of the Earth's surface than any other cloud type rendering them critical for Earth's energy balance, primarily via reflection of solar radiation, as well as their role in the global hydrological cycle. Stratocumuli are particularly sensitive to changes in aerosol loading on both microphysical and macrophysical scales, yet the complex feedbacks involved in aerosol-cloud-precipitation interactions remain poorly understood. Moreover, research on these clouds has largely been confined to marine environments, with far fewer studies over land where major sources of anthropogenic aerosols exist. The aerosol burden over Southeast Asia (SEA) in boreal spring, attributed to biomass burning (BB), exhibits highly consistent spatiotemporal distribution patterns, with major variability due to changes in aerosol loading mediated by processes ranging from large-scale climate factors to diurnal meteorological events. Downwind from source regions, the transported BB aerosols often overlap with low-level Sc cloud decks associated with the development of the region's pre-monsoon system, providing a unique, natural laboratory for further exploring their complex micro- and macro-scale relationships. Compared to other locations worldwide, studies of springtime biomass-burning aerosols and the predominately Sc cloud systems over SEA and their ensuing interactions are underrepresented in scientific literature. Measurements of aerosol and cloud properties, whether ground-based or from satellites, generally lack information on microphysical processes; thus cloud-resolving models are often employed to simulate the underlying physical processes in aerosol-cloud-precipitation interactions. The Goddard Cumulus Ensemble (GCE) cloud model has recently been enhanced with a triple-moment (3M) bulk microphysics scheme as well as the Regional Atmospheric Modeling System (RAMS) version 6 aerosol module. Because the aerosol burden not only affects cloud

  12. Primary and secondary aerosols in Beijing in winter: sources, variations and processes

    NASA Astrophysics Data System (ADS)

    Sun, Yele; Du, Wei; Fu, Pingqing; Wang, Qingqing; Li, Jie; Ge, Xinlei; Zhang, Qi; Zhu, Chunmao; Ren, Lujie; Xu, Weiqi; Zhao, Jian; Han, Tingting; Worsnop, Douglas R.; Wang, Zifa

    2016-07-01

    Winter has the worst air pollution of the year in the megacity of Beijing. Despite extensive winter studies in recent years, our knowledge of the sources, formation mechanisms and evolution of aerosol particles is not complete. Here we have a comprehensive characterization of the sources, variations and processes of submicron aerosols that were measured by an Aerodyne high-resolution aerosol mass spectrometer from 17 December 2013 to 17 January 2014 along with offline filter analysis by gas chromatography/mass spectrometry. Our results suggest that submicron aerosols composition was generally similar across the winter of different years and was mainly composed of organics (60 %), sulfate (15 %) and nitrate (11 %). Positive matrix factorization of high- and unit-mass resolution spectra identified four primary organic aerosol (POA) factors from traffic, cooking, biomass burning (BBOA) and coal combustion (CCOA) emissions as well as two secondary OA (SOA) factors. POA dominated OA, on average accounting for 56 %, with CCOA being the largest contributor (20 %). Both CCOA and BBOA showed distinct polycyclic aromatic hydrocarbons (PAHs) spectral signatures, indicating that PAHs in winter were mainly from coal combustion (66 %) and biomass burning emissions (18 %). BBOA was highly correlated with levoglucosan, a tracer compound for biomass burning (r2 = 0.93), and made a considerable contribution to OA in winter (9 %). An aqueous-phase-processed SOA (aq-OOA) that was strongly correlated with particle liquid water content, sulfate and S-containing ions (e.g. CH2SO2+) was identified. On average aq-OOA contributed 12 % to the total OA and played a dominant role in increasing oxidation degrees of OA at high RH levels (> 50 %). Our results illustrate that aqueous-phase processing can enhance SOA production and oxidation states of OA as well in winter. Further episode analyses highlighted the significant impacts of meteorological parameters on aerosol composition, size

  13. Changes in Stratiform Clouds of Mesoscale Convective Complex Introduced by Dust Aerosols

    NASA Technical Reports Server (NTRS)

    Lin, B.; Min, Q.-L.; Li, R.

    2010-01-01

    Aerosols influence the earth s climate through direct, indirect, and semi-direct effects. There are large uncertainties in quantifying these effects due to limited measurements and observations of aerosol-cloud-precipitation interactions. As a major terrestrial source of atmospheric aerosols, dusts may serve as a significant climate forcing for the changing climate because of its effect on solar and thermal radiation as well as on clouds and precipitation processes. Latest satellites measurements enable us to determine dust aerosol loadings and cloud distributions and can potentially be used to reduce the uncertainties in the estimations of aerosol effects on climate. This study uses sensors on various satellites to investigate the impact of mineral dust on cloud microphysical and precipitation processes in mesoscale convective complex (MCC). A trans-Atlantic dust outbreak of Saharan origin occurring in early March 2004 is considered. For the observed MCCs under a given convective strength, small hydrometeors were found more prevalent in the dusty stratiform regions than in those regions that were dust free. Evidence of abundant cloud ice particles in the dust regions, particularly at altitudes where heterogeneous nucleation of mineral dust prevails, further supports the observed changes of clouds and precipitation. The consequences of the microphysical effects of the dust aerosols were to shift the size spectrum of precipitation-sized hydrometeors from heavy precipitation to light precipitation and ultimately to suppress precipitation and increase the lifecycle of cloud systems, especially over stratiform areas.

  14. Improving Aerosol and Visibility Forecasting Capabilities Using Current and Future Generations of Satellite Observations

    DTIC Science & Technology

    2011-09-30

    over-ocean and over-land aerosol products have been studied with respect to surface boundary conditions, aerosol microphysics , and cloud contamination...particle size and is associated with aerosol types. Small η values relate to dust and sea salt aerosol types while large η values indicate pollutant...Similarly, microphysical biases may be an issue in greater South America and specific parts of southern Africa, India Asia, East Asia, and Indonesia

  15. Indirect and semi-direct aerosol campaign: The impact of Arctic aerosols on clouds

    SciTech Connect

    McFarquhar, Greg M.; Ghan, Steven; Verlinde, Johannes; Korolev, Alexei; Strapp, J. Walter; Schmid, Beat; Tomlinson, Jason M.; Wolde, Menqistu; Brooks, Sarah D.; Cziczo, Dan; Dubey, Manvendra K.; Fan, Jiwen; Flynn, Connor; Gultepe, Ismail; Hubbe, John; Gilles, Mary K.; Laskin, Alexander; Lawson, Paul; Leaitch, W. Richard; Liu, Peter; Liu, Xiaohong; Lubin, Dan; Mazzoleni, Claudio; Macdonald, Ann -Marie; Moffet, Ryan C.; Morrison, Hugh; Ovchinnikov, Mikhail; Ronfeld, Debbie; Shupe, Matthew D.; Xie, Shaocheng; Zelenyuk, Alla; Bae, Kenny; Freer, Matt; Glen, Andrew

    2011-02-01

    A comprehensive dataset of microphysical and radiative properties of aerosols and clouds in the boundary layer in the vicinity of Barrow, Alaska, was collected in April 2008 during the Indirect and Semi-Direct Aerosol Campaign (ISDAC). ISDAC's primary aim was to examine the effects of aerosols, including those generated by Asian wildfires, on clouds that contain both liquid and ice. ISDAC utilized the Atmospheric Radiation Measurement Pro- gram's permanent observational facilities at Barrow and specially deployed instruments measuring aerosol, ice fog, precipitation, and radiation. The National Research Council of Canada Convair-580 flew 27 sorties and collected data using an unprecedented 41 stateof- the-art cloud and aerosol instruments for more than 100 h on 12 different days. Aerosol compositions, including fresh and processed sea salt, biomassburning particles, organics, and sulfates mixed with organics, varied between flights. Observations in a dense arctic haze on 19 April and above, within, and below the single-layer stratocumulus on 8 and 26 April are enabling a process-oriented understanding of how aerosols affect arctic clouds. Inhomogeneities in reflectivity, a close coupling of upward and downward Doppler motion, and a nearly constant ice profile in the single-layer stratocumulus suggests that vertical mixing is responsible for its longevity observed during ISDAC. Data acquired in cirrus on flights between Barrow and Fairbanks, Alaska, are improving the understanding of the performance of cloud probes in ice. Furthermore, ISDAC data will improve the representation of cloud and aerosol processes in models covering a variety of spatial and temporal scales, and determine the extent to which surface measurements can provide retrievals of aerosols, clouds, precipitation, and radiative heating.

  16. Indirect and semi-direct aerosol campaign: The impact of Arctic aerosols on clouds

    DOE PAGES

    McFarquhar, Greg M.; Ghan, Steven; Verlinde, Johannes; ...

    2011-02-01

    A comprehensive dataset of microphysical and radiative properties of aerosols and clouds in the boundary layer in the vicinity of Barrow, Alaska, was collected in April 2008 during the Indirect and Semi-Direct Aerosol Campaign (ISDAC). ISDAC's primary aim was to examine the effects of aerosols, including those generated by Asian wildfires, on clouds that contain both liquid and ice. ISDAC utilized the Atmospheric Radiation Measurement Pro- gram's permanent observational facilities at Barrow and specially deployed instruments measuring aerosol, ice fog, precipitation, and radiation. The National Research Council of Canada Convair-580 flew 27 sorties and collected data using an unprecedented 41more » stateof- the-art cloud and aerosol instruments for more than 100 h on 12 different days. Aerosol compositions, including fresh and processed sea salt, biomassburning particles, organics, and sulfates mixed with organics, varied between flights. Observations in a dense arctic haze on 19 April and above, within, and below the single-layer stratocumulus on 8 and 26 April are enabling a process-oriented understanding of how aerosols affect arctic clouds. Inhomogeneities in reflectivity, a close coupling of upward and downward Doppler motion, and a nearly constant ice profile in the single-layer stratocumulus suggests that vertical mixing is responsible for its longevity observed during ISDAC. Data acquired in cirrus on flights between Barrow and Fairbanks, Alaska, are improving the understanding of the performance of cloud probes in ice. Furthermore, ISDAC data will improve the representation of cloud and aerosol processes in models covering a variety of spatial and temporal scales, and determine the extent to which surface measurements can provide retrievals of aerosols, clouds, precipitation, and radiative heating.« less

  17. Characteristics of regional aerosols: Southern Arizona and eastern Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Prabhakar, Gouri

    Atmospheric aerosols impact the quality of our life in many direct and indirect ways. Inhalation of aerosols can have harmful effects on human health. Aerosols also have climatic impacts by absorbing or scattering solar radiation, or more indirectly through their interactions with clouds. Despite a better understanding of several relevant aerosol properties and processes in the past years, they remain the largest uncertainty in the estimate of global radiative forcing. The uncertainties arise because although aerosols are ubiquitous in the Earth's atmosphere they are highly variable in space, time and their physicochemical properties. This makes in-situ measurements of aerosols vital in our effort towards reducing uncertainties in the estimate of global radiative forcing due to aerosols. This study is an effort to characterize atmospheric aerosols at a regional scale, in southern Arizona and eastern Pacific Ocean, based on ground and airborne observations of aerosols. Metals and metalloids in particles with aerodynamic diameter (Dp) smaller than 2.5 μm are found to be ubiquitous in southern Arizona. The major sources of the elements considered in the study are identified to be crustal dust, smelting/mining activities and fuel combustion. The spatial and temporal variability in the mass concentrations of these elements depend both on the source strength and meteorological conditions. Aircraft measurements of aerosol and cloud properties collected during various field campaigns over the eastern Pacific Ocean are used to study the sources of nitrate in stratocumulus cloud water and the relevant processes. The major sources of nitrate in cloud water in the region are emissions from ships and wildfires. Different pathways for nitrate to enter cloud water and the role of meteorology in these processes are examined. Observations of microphysical properties of ambient aerosols in ship plumes are examined. The study shows that there is an enhancement in the number

  18. Accelerated simulation of stochastic particle removal processes in particle-resolved aerosol models

    SciTech Connect

    Curtis, J.H.; Michelotti, M.D.; Riemer, N.; Heath, M.T.; West, M.

    2016-10-01

    Stochastic particle-resolved methods have proven useful for simulating multi-dimensional systems such as composition-resolved aerosol size distributions. While particle-resolved methods have substantial benefits for highly detailed simulations, these techniques suffer from high computational cost, motivating efforts to improve their algorithmic efficiency. Here we formulate an algorithm for accelerating particle removal processes by aggregating particles of similar size into bins. We present the Binned Algorithm for particle removal processes and analyze its performance with application to the atmospherically relevant process of aerosol dry deposition. We show that the Binned Algorithm can dramatically improve the efficiency of particle removals, particularly for low removal rates, and that computational cost is reduced without introducing additional error. In simulations of aerosol particle removal by dry deposition in atmospherically relevant conditions, we demonstrate about 50-times increase in algorithm efficiency.

  19. Identifying Aerosol Type/Mixture from Aerosol Absorption Properties Using AERONET

    NASA Technical Reports Server (NTRS)

    Giles, D. M.; Holben, B. N.; Eck, T. F.; Sinyuk, A.; Dickerson, R. R.; Thompson, A. M.; Slutsker, I.; Li, Z.; Tripathi, S. N.; Singh, R. P.; Zibordi, G.

    2010-01-01

    Aerosols are generated in the atmosphere through anthropogenic and natural mechanisms. These sources have signatures in the aerosol optical and microphysical properties that can be used to identify the aerosol type/mixture. Spectral aerosol absorption information (absorption Angstrom exponent; AAE) used in conjunction with the particle size parameterization (extinction Angstrom exponent; EAE) can only identify the dominant absorbing aerosol type in the sample volume (e.g., black carbon vs. iron oxides in dust). This AAE/EAE relationship can be expanded to also identify non-absorbing aerosol types/mixtures by applying an absorption weighting. This new relationship provides improved aerosol type distinction when the magnitude of absorption is not equal (e.g, black carbon vs. sulfates). The Aerosol Robotic Network (AERONET) data provide spectral aerosol optical depth and single scattering albedo - key parameters used to determine EAE and AAE. The proposed aerosol type/mixture relationship is demonstrated using the long-term data archive acquired at AERONET sites within various source regions. The preliminary analysis has found that dust, sulfate, organic carbon, and black carbon aerosol types/mixtures can be determined from this AAE/EAE relationship when applying the absorption weighting for each available wavelength (Le., 440, 675, 870nm). Large, non-spherical dust particles absorb in the shorter wavelengths and the application of 440nm wavelength absorption weighting produced the best particle type definition. Sulfate particles scatter light efficiently and organic carbon particles are small near the source and aggregate over time to form larger less absorbing particles. Both sulfates and organic carbon showed generally better definition using the 870nm wavelength absorption weighting. Black carbon generation results from varying combustion rates from a number of sources including industrial processes and biomass burning. Cases with primarily black carbon showed

  20. 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.

  1. A simple parameterization of aerosol emissions in RAMS

    NASA Astrophysics Data System (ADS)

    Letcher, Theodore

    Throughout the past decade, a high degree of attention has been focused on determining the microphysical impact of anthropogenically enhanced concentrations of Cloud Condensation Nuclei (CCN) on orographic snowfall in the mountains of the western United States. This area has garnered a lot of attention due to the implications this effect may have on local water resource distribution within the Region. Recent advances in computing power and the development of highly advanced microphysical schemes within numerical models have provided an estimation of the sensitivity that orographic snowfall has to changes in atmospheric CCN concentrations. However, what is still lacking is a coupling between these advanced microphysical schemes and a real-world representation of CCN sources. Previously, an attempt to representation the heterogeneous evolution of aerosol was made by coupling three-dimensional aerosol output from the WRF Chemistry model to the Colorado State University (CSU) Regional Atmospheric Modeling System (RAMS) (Ward et al. 2011). The biggest problem associated with this scheme was the computational expense. In fact, the computational expense associated with this scheme was so high, that it was prohibitive for simulations with fine enough resolution to accurately represent microphysical processes. To improve upon this method, a new parameterization for aerosol emission was developed in such a way that it was fully contained within RAMS. Several assumptions went into generating a computationally efficient aerosol emissions parameterization in RAMS. The most notable assumption was the decision to neglect the chemical processes in formed in the formation of Secondary Aerosol (SA), and instead treat SA as primary aerosol via short-term WRF-CHEM simulations. While, SA makes up a substantial portion of the total aerosol burden (much of which is made up of organic material), the representation of this process is highly complex and highly expensive within a numerical

  2. Evolution of Biomass Burning Aerosols in the Near Field

    NASA Astrophysics Data System (ADS)

    Sedlacek, Arthur; Kleinman, Lawrence; Arnott, W. Patrick; Adachi, Kouji; Buseck, Peter; Lewis, Ernest; Onasch, Timothy; pikridas, Michail; Shilling, John; Springston, Stephen; Wang, Jian; Yokelson, Robert

    2014-05-01

    Biomass burning is a significant source of aerosols that can perturb Earth's climate through the direct (both scattering and absorption), indirect (cloud formation and precipitation), and semi-direct (cloud dissipation) radiative effects. Despite much effort, quantities important to determining radiative forcing for these events still remain highly uncertain due to the inherent difficultly of conducting the required measurements and instrumentation limitations. Further adding to this uncertainty is that few field campaigns have been conducted in the northern temperate latitudes in spite of biomass burning producing about one-third of the PM2.5 in the US. During the summer and early fall of 2013, the Atmospheric Radiation Measurement (ARM) program of the U. S. Department of Energy (DOE) sponsored an aircraft-based field campaign to study the near-field evolution of particulate emissions from biomass burning. Key scientific objectives for the Biomass Burning Observation Project (BBOP) are to 1) quantify the downwind time evolution of microphysical, morphological, chemical, hygroscopic, and optical properties of aerosols generated by biomass burning, 2) use the time sequences of observations to constrain processes and parameterizations in a Lagrangian model of aerosol evolution, and 3) incorporate time evolution information into a single-column radiative transfer model for determining forcing per unit carbon burned. Discussion will be on the near-field evolution of particle mixing state and morphology, chemical composition, and microphysical processes that determine aerosol size distribution and single scattering albedo (SSA) of light absorbing aerosols. In cases studied, increases in the coating thickness of refractive black carbon (rBC) particles, organic aerosol/rBC ratio, scattering/CO ratio, and aerosol size distributions have been observed. Results are based on wildfires sampled in the US northwest and on controlled agricultural burns in the south

  3. 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.

  4. Implementation of warm-cloud processes in a source-oriented WRF/Chem model to study the effect of aerosol mixing state on fog formation in the Central Valley of California

    NASA Astrophysics Data System (ADS)

    Lee, H.-H.; Chen, S.-H.; Kleeman, M. J.; Zhang, H.; DeNero, S. P.; Joe, D. K.

    2015-11-01

    The source-oriented Weather Research and Forecasting chemistry model (SOWC) was modified to include warm cloud processes and applied to investigate how aerosol mixing states influence fog formation and optical properties in the atmosphere. SOWC tracks a 6-dimensional chemical variable (X, Z, Y, Size Bins, Source Types, Species) through an explicit simulation of atmospheric chemistry and physics. A source-oriented cloud condensation nuclei module was implemented into the SOWC model to simulate warm clouds using the modified two-moment Purdue Lin microphysics scheme. The Goddard shortwave and longwave radiation schemes were modified to interact with source-oriented aerosols and cloud droplets so that aerosol direct and indirect effects could be studied. The enhanced SOWC model was applied to study a fog event that occurred on 17 January 2011, in the Central Valley of California. Tule fog occurred because an atmospheric river effectively advected high moisture into the Central Valley and nighttime drainage flow brought cold air from mountains into the valley. The SOWC model produced reasonable liquid water path, spatial distribution and duration of fog events. The inclusion of aerosol-radiation interaction only slightly modified simulation results since cloud optical thickness dominated the radiation budget in fog events. The source-oriented mixture representation of particles reduced cloud droplet number relative to the internal mixture approach that artificially coats hydrophobic particles with hygroscopic components. The fraction of aerosols activating into CCN at a supersaturation of 0.5 % in the Central Valley decreased from 94 % in the internal mixture model to 80 % in the source-oriented model. This increased surface energy flux by 3-5 W m-2 and surface temperature by as much as 0.25 K in the daytime.

  5. Implementation of warm-cloud processes in a source-oriented WRF/Chem model to study the effect of aerosol mixing state on fog formation in the Central Valley of California

    NASA Astrophysics Data System (ADS)

    Lee, Hsiang-He; Chen, Shu-Hua; Kleeman, Michael J.; Zhang, Hongliang; DeNero, Steven P.; Joe, David K.

    2016-07-01

    The source-oriented Weather Research and Forecasting chemistry model (SOWC) was modified to include warm cloud processes and was applied to investigate how aerosol mixing states influence fog formation and optical properties in the atmosphere. SOWC tracks a 6-D chemical variable (X, Z, Y, size bins, source types, species) through an explicit simulation of atmospheric chemistry and physics. A source-oriented cloud condensation nuclei module was implemented into the SOWC model to simulate warm clouds using the modified two-moment Purdue Lin microphysics scheme. The Goddard shortwave and long-wave radiation schemes were modified to interact with source-oriented aerosols and cloud droplets so that aerosol direct and indirect effects could be studied. The enhanced SOWC model was applied to study a fog event that occurred on 17 January 2011, in the Central Valley of California. Tule fog occurred because an atmospheric river effectively advected high moisture into the Central Valley and nighttime drainage flow brought cold air from mountains into the valley. The SOWC model produced reasonable liquid water path, spatial distribution and duration of fog events. The inclusion of aerosol-radiation interaction only slightly modified simulation results since cloud optical thickness dominated the radiation budget in fog events. The source-oriented mixture representation of particles reduced cloud droplet number relative to the internal mixture approach that artificially coats hydrophobic particles with hygroscopic components. The fraction of aerosols activating into cloud condensation nuclei (CCN) at a supersaturation of 0.5 % in the Central Valley decreased from 94 % in the internal mixture model to 80 % in the source-oriented model. This increased surface energy flux by 3-5 W m-2 and surface temperature by as much as 0.25 K in the daytime.

  6. A ten-year global record of absorbing aerosols above clouds from OMI's near-UV observations

    NASA Astrophysics Data System (ADS)

    Jethva, Hiren; Torrres, Omar; Ahn, Changwoo

    2016-05-01

    Aerosol-cloud interaction continues to be one of the leading uncertain components of climate models, primarily due to the lack of an adequate knowledge of the complex microphysical and radiative processes associated with the aerosolcloud system. The situations when aerosols and clouds are found in the same atmospheric column, for instance, when light-absorbing aerosols such as biomass burning generated carbonaceous particles or wind-blown dust overlay low-level cloud decks, are commonly found over several regional of the world. Contrary to the cloud-free scenario over dark surface, for which aerosols are known to produce a net cooling effect (negative radiative forcing) on climate, the overlapping situation of absorbing aerosols over cloud can potentially exert a significant level of atmospheric absorption and produces a positive radiative forcing at top-of-atmosphere. The magnitude of direct radiative effects of aerosols above cloud depends directly on the aerosol loading, microphysical-optical properties of the aerosol layer and the underlying cloud deck, and geometric cloud fraction. We help in addressing this problem by introducing a novel product of optical depth of absorbing aerosols above clouds retrieved from near-UV observations made by the Ozone Monitoring Instrument (OMI) on board NASA's Aura platform. The presence of absorbing aerosols above cloud reduces the upwelling radiation reflected by cloud and produces a strong `color ratio' effect in the near-UV region, which can be unambiguously detected in the OMI measurements. Physically based on this effect, the OMACA algorithm retrieves the optical depths of aerosols and clouds simultaneously under a prescribed state of atmosphere. The algorithm architecture and results from a ten-year global record including global climatology of frequency of occurrence and above-cloud aerosol optical depth, and a discussion on related future field campaigns are presented.

  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. 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

  9. Chemical composition, sources, and processes of urban aerosols during summertime in Northwest China: insights from High Resolution Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Xu, J.; Zhang, Q.; Chen, M.; Ge, X.; Ren, J.; Qin, D.

    2014-06-01

    coal combustion aerosol, likely contributed by coal combustion activities in Lanzhou during summer. The sources of BC were estimated by a linear decomposition algorithm that uses the time series of the NR-PM1 components. Our results indicate that a main source of BC was local traffic (47%) and that transport of regionally processes air masses also contributed significantly to BC observed in Lanzhou. Finally, the concentration and source of polycyclic aromatic hydrocarbons (PAHs) were evaluated.

  10. Formation of highly porous aerosol particles by atmospheric freeze-drying in ice clouds.

    PubMed

    Adler, Gabriela; Koop, Thomas; Haspel, Carynelisa; Taraniuk, Ilya; Moise, Tamar; Koren, Ilan; Heiblum, Reuven H; Rudich, Yinon

    2013-12-17

    The cycling of atmospheric aerosols through clouds can change their chemical and physical properties and thus modify how aerosols affect cloud microphysics and, subsequently, precipitation and climate. Current knowledge about aerosol processing by clouds is rather limited to chemical reactions within water droplets in warm low-altitude clouds. However, in cold high-altitude cirrus clouds and anvils of high convective clouds in the tropics and midlatitudes, humidified aerosols freeze to form ice, which upon exposure to subsaturation conditions with respect to ice can sublimate, leaving behind residual modified aerosols. This freeze-drying process can occur in various types of clouds. Here we simulate an atmospheric freeze-drying cycle of aerosols in laboratory experiments using proxies for atmospheric aerosols. We find that aerosols that contain organic material that undergo such a process can form highly porous aerosol particles with a larger diameter and a lower density than the initial homogeneous aerosol. We attribute this morphology change to phase separation upon freezing followed by a glass transition of the organic material that can preserve a porous structure after ice sublimation. A porous structure may explain the previously observed enhancement in ice nucleation efficiency of glassy organic particles. We find that highly porous aerosol particles scatter solar light less efficiently than nonporous aerosol particles. Using a combination of satellite and radiosonde data, we show that highly porous aerosol formation can readily occur in highly convective clouds, which are widespread in the tropics and midlatitudes. These observations may have implications for subsequent cloud formation cycles and aerosol albedo near cloud edges.

  11. Formation of highly porous aerosol particles by atmospheric freeze-drying in ice clouds

    PubMed Central

    Adler, Gabriela; Koop, Thomas; Haspel, Carynelisa; Taraniuk, Ilya; Moise, Tamar; Koren, Ilan; Heiblum, Reuven H.; Rudich, Yinon

    2013-01-01

    The cycling of atmospheric aerosols through clouds can change their chemical and physical properties and thus modify how aerosols affect cloud microphysics and, subsequently, precipitation and climate. Current knowledge about aerosol processing by clouds is rather limited to chemical reactions within water droplets in warm low-altitude clouds. However, in cold high-altitude cirrus clouds and anvils of high convective clouds in the tropics and midlatitudes, humidified aerosols freeze to form ice, which upon exposure to subsaturation conditions with respect to ice can sublimate, leaving behind residual modified aerosols. This freeze-drying process can occur in various types of clouds. Here we simulate an atmospheric freeze-drying cycle of aerosols in laboratory experiments using proxies for atmospheric aerosols. We find that aerosols that contain organic material that undergo such a process can form highly porous aerosol particles with a larger diameter and a lower density than the initial homogeneous aerosol. We attribute this morphology change to phase separation upon freezing followed by a glass transition of the organic material that can preserve a porous structure after ice sublimation. A porous structure may explain the previously observed enhancement in ice nucleation efficiency of glassy organic particles. We find that highly porous aerosol particles scatter solar light less efficiently than nonporous aerosol particles. Using a combination of satellite and radiosonde data, we show that highly porous aerosol formation can readily occur in highly convective clouds, which are widespread in the tropics and midlatitudes. These observations may have implications for subsequent cloud formation cycles and aerosol albedo near cloud edges. PMID:24297908</