- The main objectives of AMAZE-08 were to understand the sources and regulators of organic particle mass in a pristine continental environment and the connections between particle chemistry and particle optical and hygroscopic properties. The AMAZE-08 tower measurements were conducted in Central Amazonia between February 7 and March 14, 2008 during the rainy reason.

The winds were predominantly from the ENE across 1600 km of untouched forest from the Atlantic Ocean. The overall composition of submicron Amazonian aerosol particles for background conditions is 80 to 90% organic material, with the balance in sulfate. This talk will present several new stories, especially related to nucleation and growth, that have emerged during the analysis of the AMAZE-08 data set. For example, (1) particles collected and imaged by scanning electron microscopy suggest an extremely active production of secondary organic aerosol and that the resulting organic mass dominates the submicron particle fraction. (2) The variability in the CCN activity of submicron particles can be explained by diameter and by use of an effective hygroscopicity of mixing based on an organic parameter and a sulfate parameter; the organic parameter has the same value as obtained for SOA particles in laboratory experiments. (3) A major source of ice nuclei in the wet season of the Amazon is transcontinental transport of Saharan dust; a local source of biological particles also contributes to the IN population, likely dominating at warmer temperatures where ice initiation occurs more frequently. Further examples of other emerging findings will also be presented.


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- Marine stratus clouds have been shown to have a significant cooling effect on the earth’s climate yet our understanding of the processes that control the presence of these clouds has been substantially lacking. This deficit is evident through our inability to accurately predict the behavior of these clouds in future climate scenarios. Globally, these low-level clouds cover about 25% of the world, predominately over the cool waters of the eastern boundary currents of major ocean basins. The boundary currents are also associated with areas of intense coastal upwelling of cold sub-surface ocean water. Upwelling is a highly variable, wind driven process which is why upwelling regions experience some of the world’s largest sea surface temperature variations. Varying sea surface temperatures can modulate the delivery of latent heat to the marine boundary layer through the processes of evaporation at the sea surface and condensation on atmospheric aerosols aloft. Observational evidence is presented supporting a novel hypothesis describing the relationship between sea surface temperatures, aerosols and marine stratus cloud life cycles.


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- Often described as a 'new' technology throughout the weather community, several decades of research into polarimetric scanning weather radar systems have demonstrated the usefulness of these platforms for improved radar data quality, bulk hydrometeor classification, drop-size distribution insight and enhanced surface rainfall estimation products to extended ranges. As operational weather radar networks transition toward this standard, it is important to educate potential users of these data to the strengths and weaknesses of these observations. Such topics are also of increasing interest for the U.S. Department of Energy ARM/ASR community that now seeks to improve the treatment of cloud and radiation physics in global climate models through the ingest of scanning weather radar observations in precipitating storms.


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- Atmospheric aerosols are known to exert a significant influence on the Earth’s climate system indirectly through their impacts on clouds. Compositional variability of aerosol and its impacts on cloud droplet formation (particularly when a large amount of organics are present), remain a large source of uncertainty in aerosol-cloud-climate interaction studies. We present methods to constrain this uncertainty using in-situ field observations of aerosol size distribution, chemical composition, and cloud condensation nuclei (CCN) concentrations obtained with a Droplet Measurement Technologies Continuous-Flow Streamwise Thermal-Gradient CCN Counter^1,2 (CFSTGC). We will focus on two newly-developed techniques: i) Scanning Flow CCN Analysis³ (SFCA) which provides fast measurements of CCN spectra, and, ii) Scanning Mobility CCN Analysis⁴ (SMCA), which provides size-resolved CCN activity data with high-temporal-resolution. Both techniques provide a considerable amount of information that can be used to infer the aerosol mixing state, distribution of CCN activity across particle size, and droplet activation kinetics. The high-resolution data can also be used to quantify the uncertainty associated with predictions of CCN concentration, when typical simplifying assumptions regarding aerosol composition (e.g., size-invariant composition, organics as insoluble species or soluble with constant hygroscopicity) are used. Examples of the measurement techniques and analysis will be presented using i) airborne observations in Arctic air masses collected during the NOAA ARCPAC campaign (April, 2008), and, ii) ground-based observations in Atlanta collected from August 2008-August 2009.


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- A recent version of Canadian climate model CCCma AGCM4 includes new treatment of aerosol and clouds into the physics package. Five major aerosol species of sulphate, sea salt, mineral dust, organic carbon and black carbon are considered. The model approach accounts for emissions, advection, sulphate gas-phase and in-cloud production, sedimentation, dry and wet deposition of aerosols. Mass burden and optical depth for different aerosol species are compared with other models and with different satellite systems, in order to validate AGCM4 for its aerosol simulation.

Radiative effect of clouds is related to aerosol and cloud properties. In AGCM4, Mass flux schemes for deep and shallow convection, as well as a prognostic scheme of layered clouds are employed. Satellite simulators enable a comparison of cloud results between model and satellite observations. Using this tool, cloud radiative effects are validated with a match to satellite retrievals.

Anthropogenic activity leads to an increasing amount of aerosols, which in turn modifies cloud property and regulates the radiative effect. In AGCM4, the indirect aerosol effect is realized through a parameterization of droplet number and size of layered clouds. A relationship between the cloud droplet effective radius and aerosol amount can be derived from model results and satellite data. This investigation helps to understand the dependence of indirect effect on different aerosol species. The parameterization of aerosol influence on clouds can be adjusted accordingly, too.


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- Electrospray (ES), uni-polar charger and differential mobility analyzer (DMA) are three relatively mature aerosol instruments and had attracted many attentions from researchers in the area of aerosol science and technology.

In this research, an ES-charger-DMA coupling system is developed. Three units ö ES, charger, DMA in this system are redesigned to achieve the optimized performance of the whole system. The experimental study investigates the operation mode, the size distribution of produced droplets or capsules from an electrospray unit. Particle/droplet encapsulation is addressed and the criteria of proper operating a dual capillary ES system are discussed. The whole system evaluation is also carried out and it is demonstrated that the coupled system can analyze particles as small as 1 nm.

Based on the experimental observation and the fundamental understanding, we combine the ES-charge-DMA system with aerosol mass spectrometer (AMS). The study of control-release drug is launched, assisting by a series of detailed characterization. The research shows that the ES-charge-DMA-AMS system provides a new one-step technique to characterize macromolecule or coated particles with size distribution and chemical composition.


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- Ambient air contains particulate matter and gaseous species which are generated by nature means or by anthropogenic activities such as energy consumption. Research has demonstrated adverse health effects of some bioaerosol and energy-consumption related contaminants. Providing effective sampling, concentration, and characterization methods for particles and gases is necessary not only to monitor ambient air quality but also to provide potential for an alert in case of bio-terrorism attacks.

A near-real-time bioaerosol detection system includes three major components: a sampling inlet, a concentrator or collector, and a detector or identifier. Focus herein will be on the first two components of a detection system. Computational Fluid Dynamics (CFD) technology was used to investigate fluid and thermal behaviors of the flows and particle trajectories in these devices, and to optimize the performance. Wetted-wall cyclones, circumferential slot virtual impactors, together with newly developed inlets fitted with in-line real and virtual impactor, were integrated into bioaerosol sampling and concentration systems that consume little electrical power but have high performance.

Urban ambient air quality is impacted by various sources such as fuel combustion by vehicles and aircraft. The resulting strong concentration gradients of particles and gases in residential and commercial areas have implications for human exposure assessment and urban planning. We have employed an instrumented mobile platform as a powerful means to map real-time high-resolution pollutant concentrations and gradients in the Los Angeles basin, as well as to identify localized hot spot areas with elevated pollutant concentrations.

Future investigations will focus on the development and improvement of sampling, concentration, and characterization technologies for particulate matter and gaseous species associated with energy consumption and resulting environmental impacts.


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- Submicron aerosol particles in Beijing, China were studied with Aerodyne Aerosol Mass Spectrometers (AMS) in the summers of 2006 and 2008 through our collaborations with the Peking University (PKU) of China and the Chinese Academy of Meteorological Services (CAMS). The 2008 AMS study was part of the Campaigns of Air Quality Research in Beijing (i.e., CAREBEIJING) to study the impact of urban emission controls on air quality during the 2008 Olympic Games (August 8-24). The characteristics, sources, and photochemical processes of organic aerosol particles in this polluted megacity will be discussed based on the highly time- and size-resolved AMS data together with measurements of trace gases, particle physics, and meteorological conditions. In addition, the impacts of air pollution control on the chemistry, formation, and growth of organic particles will be investigated by comparing data acquired before, during and after the Olympic emission control period.


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- Marine boundary layer (MBL) clouds can significantly regulate the sensitivity of climate models, yet they are currently poorly simulated. In this talk I will present the analyses of the observed and simulated MBL clouds, their physical and dynamical properties at seasonal and synoptic time scales. I will first use multi-satellite data, along with ARM balloon soundings as well as reanalysis products to characterize the seasonal variations of physical properties of these clouds and their associated processes. The similar properties simulated by NCAR CAM will then be analyzed in parallel. Emphasis will be placed on how the variations of MBL clouds are related with the MBL structures, and what are the controlling factors.

The synoptic scale MBL cloud modeling in this talk, using CAM and WRF for a case study of cold-air outbreak over the North Atlantic, aims to study the cause of the failure of the global models in simulating MBL clouds. The global model is shown to simulate the large-scale circulation that can support the boundary layer instabilities responsible for the observed MBL clouds, but because the global model does not resolve the unstable modes, the instabilities cannot be realized. The resolution requirement for simulating these clouds will be discussed. The successful simulations of the MBL clouds by WRF at high resolutions and the proper simulation of the large-scale circulation by CAM, demonstrates the feasibility of cloud parameterizations by nesting high resolution models into coarse resolution models to tap into the dynamical properties of the large-scale flows.

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- The understanding of the contribution of fine particles to health effects, visibility and radiative balance is aided by appropriate source apportionment results. Use of semi-continuous data should improve source apportionment analysis because data will be available on the time frame at which changes occur in the atmosphere. Apportionment results obtained from such data should significantly improve our understanding of the sources, chemical conversion processes and meteorological processes which lead to observed PM2.5 concentrations and will aid in the understanding of PM2.5 effects. Instruments should be used which will accurately determine the semi-volatile organic material and ammonium nitrate in fine particles.

Instruments used in the studies to be presented included the FDMS TEOM and the GRIMM monitor (to measure PM2.5 mass, including the semi-volatile material), a conventional TEOM monitor, a newly developed dual oven Sunset Laboratory ambient carbon monitor (to measure EC and both nonvolatile and semi-volatile carbonaceous material), an Aethalometer (to measure BC) and ion chromatographic based sampler such as the URG AIM. (to measure nitrate and sulfate). Hourly averaged data was collected for each instrument. We have also included hourly averaged measurements of NO_x, NO₂, CO and O₃ for use in PMF2 source apportionment analyses. In a study at Riverside CA, time-of-flight mass spectrometry data were also added to the analysis. The value of such apportionment analysis approaches will be illustrated with results obtained from studies in Fresno, CA (2003) and Riverside, CA (2005). The role sources play in visibility degradation will also be examined by adding extinction data to the PMF analysis for Fresno.

Finally, the development of an instrument for the hourly averaged measurement of organic marker compounds (e.g., levoglucosan, cholesterol, hopane, etc.) will be described. This instrument is based on the thermal volatilization of compounds collected on a filter and transfer to and separation by a resistively heated GC column, followed by detection and quantization using a Toroidal ion trap Mass spectrometer. The potential use of the instruments used in the Riverside study, the organic marker monitor and a rotating Drum sampler for hourly averaged elemental data by PIXE will be outlined.

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- Regional climate change can arise from three different effects: regional changes to the amount of radiative heating that reaches the Earthâs surface, an inhomogeneous response to globally uniform changes in radiative heating and variability without a specific forcing. The relative importance of these effects is not clear, particularly because neither the response to regional forcings nor the regional forcings themselves are well-known for the 20th century. I will discuss prior results that shed some light on these issues, as well as new investigations of the sensitivity of regional climate to changes in carbon dioxide, black carbon aerosols, sulfate aerosols and ozone in the tropics, mid-latitudes and polar regions, using a coupled ocean-atmosphere model. The new results indicate that mid- and high-latitude climate is quite sensitive to the location of the forcing. Using these relationships between forcing and response along with observations of 20th century climate change, I will show that we can reconstruct radiative forcing from aerosols in space and time. Our reconstructions broadly agree with historical emissions estimates, and can explain the differences between observed changes in Arctic temperatures and expectations from non-aerosol forcings plus unforced variability. I will show that the results suggest that aerosol forcing has contributed strongly to the divergence between temperature trends in the Northern Hemisphere mid-latitudes and the global mean from the 1930s onwards, and that decreasing concentrations of sulfate aerosols and increasing concentrations of black carbon have substantially contributed to rapid Arctic warming during the past three decades.


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- Biogenic sources as well as human activities contribute large amounts of volatile organic compounds to the atmosphere. Upon oxidation, polyfunctional molecules such as dicarboxylic acids are formed. These molecules generally have lower vapor pressures than the parent molecules and are able to condense on existing particles or maybe even participate in formation of new particles in the atmosphere.

Current knowledge about the thermodynamic properties governing this partitioning as well as the influence of the organic molecules on properties of aqueous solution droplets is poor. We have therefore developed new methods based on the HTDMA and EDB (Hygroscopicity Tandem Differential Mobility Analyzer, electrodynamic balance) techniques for determining the subcooled liquid state and solid state vapor pressure as well as other thermodynamic properties of secondary organic aerosol components. We have recently measured evaporation rates of crystals [1] and aqueous solution droplets containing one dicarboxylic acid (C3 to C5) and water [2-3-4]. We are currently expanding the list of organics and investigate more complicated systems such as mixed inorganic/ organic particles.

References:

1. Zardini, A. A. and Krieger, U. K. Evaporation kinetics of a non-spherical, levitated aerosol particle using optical resonance spectroscopy for precision sizing. Optics Express 17(6), 4659-4669 (2009).
2. Koponen, I. K. Thermodynamic properties of malonic, succinic, and glutaric acids: Evaporation rates and saturation vapor pressures. Environ. Sci. Technol. 41(11), 3926-3933 (2007).
3. Riipinen, I. A method for determining thermophysical properties of organic material in aqueous solutions: Succinic acid. Atmos. Res. 82(3-4), 579-590 (2006).
4. Zardini, A. A., et al. White light Mie resonance spectroscopy used to measure very low vapor pressures of substances in aqueous solution aerosol particles. Optics Express 14, 6951-6962 (2006).


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- Dr. North will try to show how energy balance models came about, starting with early history by Ahrennius through Budyko and Sellers. Then a quick review of global average models: solutions and stability theory; then latitudinal dependence with ice caps, followed by seasonal cycling, stochastic modeling and a few applications. In particular, I would like to show how the Milankovitch Theory of the Ice Ages was saved by the greenhouse effect. There are some remaining unsolved problems including stability theory and moisture budgets in paleoclimate problems.

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- We report on the development, application and performance characterization of novel gas analyzers based on cavity-enhanced laser absorption spectroscopy. These relatively novel analyzers require only about 100 watts of power and do not need liquid nitrogen. The Fast Greenhouse Gas Analyzer (FGGA) provides simultaneous measurements of methane, carbon dioxide and water vapor in ambient air in the field and on aircraft for applications that require high data rates (eddy correlation flux), wide dynamic range (e.g., chamber flux and other applications with concentrations that are 100 times typical ambient levels or higher), and highest accuracy (atmospheric monitoring stations). The FGGA provides continuous measurements at data rates up to 20 Hz and with replicate precision of 1 ppbv for methane (1 second measurement time), 0.2 ppmv for carbon dioxide (1 second measurement time) and 100 ppmv for water vapor (1 second measurement time). The Carbon Dioxide Isotope Analyzer provides simultaneous measurements of carbon dioxide concentration and ?¹³C (0.25 per mil in 60 seconds) in ambient air in measurement times as short as 1 second. The Liquid Water Isotope Analyzer reports simultaneous measurements of ?¹⁸O and ?²H in liquid water samples with a precision better than many Isotope Ratio Mass Spectrometers and with a throughput of over 120 samples per day. Along with a brief description of the operational principles of these instruments, several examples of field deployments will be presented.

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- Cloud optical properties are the most poorly known among those parameters that determine Earthâs radiative energy budget. To retrieve cloud optical properties from ground-based observations, the atmospheric science community has widely used shortwave flux measurements supplemented with microwave radiometric data. However, flux-based methods work only for overcast clouds, and fail badly for broken clouds. I will present a new method to retrieve cloud optical properties from zenith radiances in all (including broken) cloud situations. I will also show analyses of observations in the transition zone between clear and cloudy areas, which has considerable bearing on the aerosol indirect effect. Examples shown will use data from the Atmospheric Radiation Measurement (ARM) program, the Micro-Pulse Lidar Network (MPLNET), and the Aerosol Robotic Network (AERONET).

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- Atmospheric new particle formation (NPF) affects climate through its effect on concentrations of cloud condensation nuclei (CCN). NPF is important because: nucleation rates in the boundary layer are much higher (~108X) than predicted by earlier models, and growth rates of freshly nucleated particles are about 10X higher than can be explained by the condensation of H2SO4 alone. Our work combines constrained models and new instrumentation to parameterize the formation of CCN from newly formed particles by studying: [1] the dynamics of nucleated clusters; [2] correlations of nucleation rates with [H₂SO₄]; [3] ambient 1-6 nm aerosol size distributions; and [4] the survival probability of newly formed particles growing to 100 nm.

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- Aerosol effects on climate are sensitive to their composition, size and mixing state, however the character of atmospheric aerosols remains poorly constrained. A new detailed aerosol microphysical scheme, MATRIX, embedded within the global GISS modelE climate model provides the capability to probe a large range of possible aerosol climatologies, and then explore how these variations would affect climate.

Aerosols are directly released as particles or formed through secondary particle formation in the atmosphere. Condensation and coagulation processes lead to further aerosol growth, aging and internal mixing.Ê 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. MATRIX 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, such as condensation, coagulation, emission size distributions etc. on aerosol cloud activation and radiative forcing.

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- The accurate representation of clouds in radiation schemes is crucial for climate prediction, yet substantial biases still remain due to unrepresented cloud structure. I this talk I will first discuss results from radar to characterize the important properties of cloud verticalÊoverlap and horizontal heterogeneity. I will then present a new method forÊrepresenting these properties efficiently in a radiation scheme, and use it to estimate the global effect on cloud radiative forcing. Considerable regional structure is found in the change to net forcing; inÊmarine stratocumulus regions the shortwave horizontal inhomogeneity effect is dominant, while in the Pacific Warm Pool region, there is a large degree of cancellation between the effects of in homogeneity and overlap. Finally the issue of three-dimensional radiative transfer will be addressed, including a new method to represent radiative transport through cloud sides by modifying the two-stream equations of radiative transfer at a fundamental level.

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- Transmission electron microscopy studies of single atmospheric aerosol particles and laboratory-generated particles will be reported. Studies include deliquescence and eflorescence phase transitions and examination of the three dimensional structure of soot aggregates by a novel tomographic approach.

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- Soot, formed during incomplete combustion, is composed of LAC and organic matter. LAC, also called black carbon (BC), is the dominant absorber of visible solar radiation and plays a major role in climate change as a warming agent second only to CO2 (RC2008). As LAC ages during atmospheric transport, organic and inorganic matter can deposit on these particles; the coating increases the mass absorption cross-section of LAC by as much as 50% (B2006). The mixing state of LAC also determines its atmospheric lifetime as well as its ability to nucleate ice/liquid droplets.

The SP2 is a laser-induced incandescence instrument developed to measure LAC at the single-particle level. The low (<1Êfg-LAC) detection limit enables highly time-resolved data collection, as in airborne measurements. The SP2 is also equipped with a scattering detector that allows determination of LAC mixing state. Measurements over Mexico in 2006 (on the NCAR C-130) show a transition from thinly-coated LAC over Mexico City to more thickly-coated LAC after a day of atmospheric transport. Comparison of particulate light absorption measured with a particle soot absorption photometer (PSAP) and the SP2 LAC suggests a LAC absorption cross-section of 12.8 m2/g at 660Ênm, apparently unaffected by aging.

The Ice in Clouds Experiment (ICE-L) was conducted over Colorado and Wyoming in November/December 2007. Here, the SP2 was operated downstream of a counterflow virtual impactor (CVI) onboard the NCAR C-130 aircraft, to look at LAC in cloud residual nuclei. Preliminary results from this study will also be presented.

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