Published by: OMM ; 2017
Language(s): Spanish; Other Languages: English, French
Format: Digital (Free)
Published by: OMM ; 2017
Language(s): French; Other Languages: English, Spanish
Format: Digital (Free)
Published by: WMO ; 2017
Language(s): English; Other Languages: French, Spanish
Format: Digital (Free)It is the goal of the Global Atmosphere Watch (GAW) programme to ensure long - term measurements in order to detect trends in global distributions of chemical constituents in air and the reasons for them (WMO, 2001a). With respect to aerosols, the objective of GAW is to determine the spatio - temporal distribution of aerosol properties related to climate forcing and air quality on multi - decadal time scales and on regional, hemispheric and global spatial scales. The objective of GAW Report No. 153, published in 2003, was to provide a synthesis of methodologies and procedures for measuring the ...Published by: WMO ; 2016 (2nd edition)
It is the goal of the Global Atmosphere Watch (GAW) programme to ensure long - term measurements in order to detect trends in global distributions of chemical constituents in air and the reasons for them (WMO, 2001a). With respect to aerosols, the objective of GAW is to determine the spatio - temporal distribution of aerosol properties related to climate forcing and air quality on multi - decadal time scales and on regional, hemispheric and global spatial scales. The objective of GAW Report No. 153, published in 2003, was to provide a synthesis of methodologies and procedures for measuring the recommended aerosol variables within the GAW network. The report has been extensively used by the scientific community, and more particularly by scientists and engineers involved with data production from ground - based sites. The knowledge of aerosol impact on climate and air quality as well as the techniques used for the determination of the essential aerosol variables to be monitored at ground - based sites have considerably evolved in the last decade, justifying an update of GAW Report No. 153. This update has been prepared shortly after the release of the Working Group 1 report from the International Panel on Climate Change (IPCC, 2013). A clear emphasis was given for the first time in IPCC reports since 1992 to the analyses of evidence of climate change from observations of the atmosphere highlighting the challenges for d eveloping long - term, high quality observation record that can be used to constrain models at global and regional scales. While the benefit of improved monitoring capabilities developed in the last decades, both from satellites and ground - based has been cl early assessed for the production of more reliable data records, the report still highlights the need for maintaining and enhancing the capacity of the observing system to provide the additional constrains, in particular for the derivation of trends.
Language(s): English; Other Languages: Chinese
Format: Digital (Free)
ISBN (or other code): 978-92-63-11177-7This lesson introduces you to three of the four near-infrared imager bands (at 1.37, 1.6, and 2.2 micrometers) on the GOES R-U ABI (Advanced Baseline Imager), focusing on their spectral characteristics and how they affect what each band observes. For information on the 0.86 micrometer near-IR "veggie" band which is not included here, refer to the Visible and Near-IR Bands lesson. This lesson is a part of the NWS Satellite Foundation GOES-R Course.Published by: The University Corporation for Atmospheric Research ; 2016
This lesson introduces you to three of the four near-infrared imager bands (at 1.37, 1.6, and 2.2 micrometers) on the GOES R-U ABI (Advanced Baseline Imager), focusing on their spectral characteristics and how they affect what each band observes. For information on the 0.86 micrometer near-IR "veggie" band which is not included here, refer to the Visible and Near-IR Bands lesson. This lesson is a part of the NWS Satellite Foundation GOES-R Course.
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Format: Digital (Standard Copyright)This lesson introduces seven of the ten infrared imager bands on the GOES R-U ABI (Advanced Baseline Imager). It examines the spectral characteristics of each band to facilitate a better understanding of band selection and what each band observes, and to shed light on some of the many potential applications. This lesson is a part of the NWS Satellite Foundation GOES-R Course.PermalinkThis lesson introduces you to the two visible and one of the near-infrared imager bands on the GOES R-U ABI (Advanced Baseline Imager), focusing on their spectral characteristics and how they affect what each band observes. Also included is a brief discussion of the customization of visible enhancements as an important consideration for improving the depiction of various features of interest. This lesson is a part of the NWS Satellite Foundation GOES-R Course.PermalinkPermalinkAerosols are small, micrometer-sized particles, whose optical effects coupled with their impact on cloud properties is a source of large uncertainty in climate models. Aerosols when inhaled are believed to have significant and detrimental effects on human health. Their presence also affects photosynthesis and agricultural production. Aerosol measurements are urgently required for the complete understanding and modeling their role in the climate system. This study builds on the analysis of Aerosol Optical depth (AOD) using Light Detection and Ranging (LIDAR) and sun photometer measurements then ...PermalinkThis paper examines the aerosol extinction coefficient profiles measured by Rayleigh-Raman-Mie-Lidar (RRML) system in Nanjing, China. I introduced two lidars methods (Raman and Fernald) and detection principle, and two lidars data Using Raman analysis method and Fernald analysis method to obtained aerosol extinction coefficient. Aerosol profiles at 607 nm and 532 nm over ranges from 6 km to 10 km were obtained using respectively Raman lidar and Rayleigh lidar in Nanjing.Permalink
PermalinkAerosols in the atmosphere serve as condensation nuclei for the cloud formation. This brings an important influence on the microphysical properties of cloud water that in turn affect the processes in the formation of precipitation. Aerosol-cloud-precipitation interaction which simultaneously change cloud albedo interest many studies to find out aerosol impact on precipitation formation. The studies were done by observation measurement and simulation. UK Met Office Unified Model (UM) is one model that includes aerosol direct and indirect effect in the NWP configuration which leads to study aero ...PermalinkThis extension of the COMET lesson “GOES-R: Benefits of Next Generation Environmental Monitoring” focuses on the ABI instrument, the satellite's 16-channel imager. With increased spectral coverage, greater spatial resolution, more frequent imaging, and improved image pixel geolocation and radiometric performance, the ABI will bring significant advancements to forecasting, numerical weather prediction, and climate and environmental monitoring. The first part of the lesson introduces the ABI's key features and improvements over earlier GOES imagers. The second section lets users interactively ex ...Permalink
PermalinkSuspended particulate matter in the atmosphere, commonly known as aerosol by the technical and scientific community, plays a role in climate change, air quality/human health, ozone depletion and the long-range transport and deposition of toxics and nutrients. Aerosols have many sources ranging from sea spray and mineral dust that are mechanically generated by wind at the Earth’s surface to sulphates, nitrates and organics produced primarily by chemical reaction of gases in the atmosphere producing non-volatile products that condense to form particles. In addition, semi-volatile substances such ...PermalinkA five-year dataset of spectral aerosol optical thickness was used to analyse the seasonal variability of aerosol optical properties (the aerosol optical thickness (AOT) at wavelength λ=500 nm, AOT(500) and the Ångström exponent for the 440-870 nm spectral range, α(440, 870)) over the Baltic Sea and dependence of these optical properties on meteorological factors (wind direction, wind speed and relative humidity). The data from the Gotland station of the global radiometric network AERONET (Aerosol Robotic Network, http://aeronet.gsfc.nasa.gov) were taken to be representative of the Baltic Sea ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Korhonen H.; Sihto S.-L.; Kerminen V.-M.; et al. - Copernicus GmbH, 2011Several mathematical tools have been developed in recent years to analyze new particle formation rates and to estimate nucleation rates and mechanisms at sub-3 nm sizes from atmospheric aerosol data. Here we evaluate these analysis tools using 1239 numerical nucleation events for which the nucleation mechanism and formation rates were known exactly. The accuracy of the estimates of particle formation rate at 3 nm (J3) showed significant sensitivity to the details of the analysis, i.e. form of equations used and assumptions made about the initial size of nucleating clusters, with the fraction o ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Schmeissner T.; Krejci R.; Ström J.; et al. - Copernicus GmbH, 2011The first long-term measurements of aerosol number and size distributions in South-American tropical free troposphere (FT) were performed from March 2007 until March 2009. The measurements took place at the high altitude Atmospheric Research Station Alexander von Humboldt. The station is located on top of the Sierra Nevada mountain ridge at 4765 m a.s.l. nearby the city of Mérida, Venezuela. Aerosol size distribution and number concentration data was obtained with a custom-built Differential Mobility Particle Sizer (DMPS) system and a Condensational Particle Counter (CPC). The analysis of the ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Ten Hoeve J.E.; Remer L.A.; Jacobson M.Z. - Copernicus GmbH, 2011Aerosol, cloud, water vapor, and temperature profile data from the Moderate Resolution Imaging Spectroradiometer (MODIS) are utilized to examine the impact of aerosols on clouds during the Amazonian biomass burning season in Rondônia, Brazil. It is found that increasing background column water vapor (CWV) throughout this transition season between the Amazon dry and wet seasons likely exerts a strong effect on cloud properties. As a result, proper analysis of aerosol-cloud relationships requires that data be stratified by CWV to account better for the influence of background meteorological vari ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Donahue N.M.; Epstein S.A.; Pandis S.N.; et al. - Copernicus GmbH, 2011We develop the thermodynamic underpinnings of a two-dimensional volatility basis set (2D-VBS) employing saturation mass concentration (Co) and the oxygen content (O:C) to describe volatility, mixing thermodynamics, and chemical evolution of organic aerosol. The work addresses a simple question: "Can we reasonably constrain organic-aerosol composition in the atmosphere based on only two measurable organic properties, volatility and the extent of oxygenation?" This is an extension of our earlier one-dimensional approach employing volatility only (C* = γ Co, where γ is an activity coefficient). U ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Held A.; Brooks I.M.; Leck C.; et al. - Copernicus GmbH, 2011We present direct eddy covariance measurements of aerosol number fluxes, dominated by sub-50 nm particles, at the edge of an ice floe drifting in the central Arctic Ocean. The measurements were made during the ice-breaker borne ASCOS (Arctic Summer Cloud Ocean Study) expedition in August 2008 between 2°–10° W longitude and 87°–87.5° N latitude. The median aerosol transfer velocities over different surface types (open water leads, ice ridges, snow and ice surfaces) ranged from 0.27 to 0.68 mm s−1 during deposition-dominated episodes. Emission periods were observed more frequently over the open ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Jaeglé L.; Quinn P.K.; Bates T.S.; et al. - Copernicus GmbH, 2011We combine in situ measurements of sea salt aerosols (SS) from open ocean cruises and ground-based stations together with aerosol optical depth (AOD) observations from MODIS and AERONET, and the GEOS-Chem global chemical transport model to provide new constraints on SS emissions over the world's oceans. We find that the GEOS-Chem model using the Gong (2003) source function overestimates cruise observations of coarse mode SS mass concentrations by factors of 2–3 at high wind speeds over the cold waters of the Southern, North Pacific and North Atlantic Oceans. Furthermore, the model systematical ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Markovic M.Z.; Hayden K.L.; Murphy J.G.; et al. - Copernicus GmbH, 2011The Border Air Quality and Meteorology Study (BAQS-Met) was an intensive, collaborative field campaign during the summer of 2007 that investigated the effects of transboundary pollution, local pollution, and local meteorology on air quality in southwestern Ontario. This analysis focuses on the measurements of the inorganic constituents of particulate matter with diameter of less than 1 μm (PM1), with a specific emphasis on nitrate. We evaluate the ability of AURAMS, Environment Canada's chemical transport model, to represent regional air pollution in SW Ontario by comparing modelled aerosol in ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Miyazaki Y.; Kawamura K.; Jung J.; et al. - Copernicus GmbH, 2011Marine aerosol samples were collected over the western North Pacific along the latitudinal transect from 44° N to 10° N in late summer 2008 for measurements of organic nitrogen (ON) and organic carbon (OC) as well as isotopic ratios of total nitrogen (TN) and total carbon (TC). Increased concentrations of methanesulfonic acid (MSA) and diethylammonium (DEA+) at 40–44° N and subtropical regions (10–20° N) together with averaged satellite chlorophyll-a data and 5-day back trajectories suggest a significant influence of marine biological activities on aerosols in these regions. ON exhibited incre ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Tapia A.; Villanueva F.; Salgado M.S.; et al. - Copernicus GmbH, 2011A study of the kinetics and products obtained from the reactions of 3-methylfuran with the main atmospheric oxidants has been performed. The rate coefficients for the gas-phase reaction of 3-methylfuran with OH and NO3 radicals have been determined at room temperature and atmospheric pressure (air and N2 as bath gases), using a relative method with different experimental techniques. The rate coefficients obtained for these reactions were (in units cm3 molecule−1 s−1) kOH = (1.13 ± 0.22) × 10−10 and kNO3 = (1.26 ± 0.18) × 10−11. Products from the reaction of 3-methylfuran with OH, NO3 and Cl at ...PermalinkThis study compares the properties of atmospheric dust from the Saharan deserts and the Asian deserts using data from CALIPSO and AERONET during 2006 and 2007 along with simulations using a coupled climate-microphysical sectional model. Saharan deserts are largely south of 30° N, while Asian ones are primarily north of 30° N, hence they experience different meteorological regimes. Saharan dust lifting occurs all year long, primarily due to subtropical weather systems. However, Asian dust is lifted mostly in spring when mid-latitude frontal systems lead to high winds. Rainfall is more abundant ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Xu J.; Li C.; Shi H.; et al. - Copernicus GmbH, 2011This study investigated the decadal variation of the direct surface solar radiation (DiSR) and the diffuse surface solar radiation (DfSR) during 1961–2008 in the Shanghai megacity as well as their relationships to Aerosol Optical Depth (AOD) under clear-sky conditions. Three successive periods with unique features of long term variation of DiSR were identified for both clear-sky and all-sky conditions: a "dimming" period from the late 1960s to the mid 1980s, a "stabilization"/"slight brightening" period from the mid 1980s to the mid 1990s, and a "renewed dimming" period thereafter. During the ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Stroud C.A.; Makar P.A.; Moran M.D.; et al. - Copernicus GmbH, 2011Regional-scale chemical transport model predictions of urban organic aerosol to date tend to be biased low relative to observations, a limitation with important implications for applying such models to human exposure health studies. We used a nested version of Environment Canada's AURAMS model (42- to- 15- to- 2.5-km nested grid spacing) to predict organic aerosol concentrations for a temporal and spatial domain corresponding to the Border Air Quality and Meteorology Study (BAQS-Met), an air-quality field study that took place in the southern Great Lakes region in the summer of 2007. The use o ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 7. Vakkari V.; Laakso H.; Kulmala M.; et al. - Copernicus GmbH, 2011This study is based on 18 months (20 July 2006–5 February 2008) of continuous measurements of aerosol particle size distributions, air ion size distributions, trace gas concentrations and basic meteorology in a semi-clean savannah environment in Republic of South Africa. New particle formation and growth was observed on 69% of the days and bursts of non-growing ions/sub-10 nm particles on additional 14% of the days. This new particle formation frequency is the highest reported from boundary layer so far. Also the new particle formation and growth rates were among the highest reported in the li ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 5. Pitts M.C.; Poole L.R.; Dörnbrack A.; et al. - Copernicus GmbH, 2011Spaceborne lidar measurements from CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) are used to provide a vortex-wide perspective of the 2009–2010 Arctic PSC (polar stratospheric cloud) season to complement more focused measurements from the European Union RECONCILE (reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions) field campaign. The 2009–2010 Arctic winter was unusually cold at stratospheric levels from mid-December 2009 until the end of January 2010, and was one of only ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 5. El Haddad I.; Marchand N.; Temime-Roussel B.; et al. - Copernicus GmbH, 2011A comprehensive aerosol characterization was conducted at Marseille during summer, including organic (OC) and elemental carbon (EC), major ionic species, radiocarbon (14C), water-soluble OC and HULIS (HUmic LIke Substances), elemental composition and primary and secondary organic markers. This paper is the second paper of a two-part series that uses this dataset to investigate the sources of Organic Aerosol (OA). While the first paper investigates the primary sources (El Haddad et al., 2010), this second paper focuses on the secondary fraction of the organic aerosol.PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 5. El Haddad I.; Marchand N.; Wortham H.; et al. - Copernicus GmbH, 2011Marseille, the most important port of the Mediterranean Sea, represents a challenging case study for source apportionment exercises, combining an active photochemistry and multiple emission sources, including fugitive emissions from industrial sources and shipping. This paper presents a Chemical Mass Balance (CMB) approach based on organic markers and metals to apportion the primary sources of organic aerosol in Marseille, with a special focus on industrial emissions. Overall, the CMB model accounts for the major primary anthropogenic sources including motor vehicles, biomass burning and the a ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 5. Gerasopoulos E.; Amiridis V.; Kazadzis S.; et al. - Copernicus GmbH, 2011Three years (2006–2008) of ground-based observations of the Aerosol Optical Depth (AOD) in the urban environment of Athens, in the Eastern Mediterranean, are analysed in this work. Measurements were acquired with a Multi-Filter Rotating Shadowband Radiometer at five wavelengths. The daily average AOD at 500 nm is 0.23, and the mean Ångström coefficient calculated between 415 and 867 nm is 1.41. The annual variability of AOD has a spring maximum dominated by coarse dust particles from the Sahara (AOD 0.34–0.42), while the diurnal pattern is typical for urban sites, with AOD steadily increasing ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 5. Barlow J.F.; Dunbar T.M.; Nemitz E.G.; et al. - Copernicus GmbH, 2011Urban boundary layers (UBLs) can be highly complex due to the heterogeneous roughness and heating of the surface, particularly at night. Due to a general lack of observations, it is not clear whether canonical models of boundary layer mixing are appropriate in modelling air quality in urban areas. This paper reports Doppler lidar observations of turbulence profiles in the centre of London, UK, as part of the second REPARTEE campaign in autumn 2007. Lidar-measured standard deviation of vertical velocity averaged over 30 min intervals generally compared well with in situ sonic anemometer measure ...PermalinkThis study examines the dependence of aerosol-precipitation interactions on environmental humidity in a mesoscale cloud ensemble (MCE) which is composed of convective and stratiform clouds. The author found that increases in aerosol concentration enhance evaporative cooling, which raises not only the intensity of vorticity and entrainment but also that of downdrafts and low-level convergence. The increase in vorticity tends to suppress precipitation. The increase in low-level convergence tends to enhance precipitation by generating more secondary clouds in a muptiple-cloud system simulated her ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 5. Wagner R.; Möhler O.; Saathoff H.; et al. - Copernicus GmbH, 2011The heterogeneous ice nucleation ability of oxalic acid in the immersion mode has been investigated by controlled expansion cooling runs with airborne, ternary solution droplets composed of, (i), sodium chloride, oxalic acid, and water (NaCl/OA/H2O) and, (ii), sulphuric acid, oxalic acid, and water (H2SO4/OA/H2O). Polydisperse aerosol populations with median diameters ranging from 0.5–0.7 μm and varying solute concentrations were prepared. The expansion experiments were conducted in the AIDA aerosol and cloud chamber of the Karlsruhe Institute of Technology at initial temperatures of 244 and 2 ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Brock C.A.; Cozic J.; Bahreini R.; et al. - Copernicus GmbH, 2011We present an overview of the background, scientific goals, and execution of the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) project of April 2008. We then summarize airborne measurements, made in the troposphere of the Alaskan Arctic, of aerosol particle size distributions, composition, and optical properties and discuss the sources and transport of the aerosols. The aerosol data were grouped into four categories based on gas-phase composition. First, the background troposphere contained a relatively diffuse, sulfate-rich aerosol extending from the top of the sea ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Barletta B.; Nissenson P.; Meinardi S.; et al. - Copernicus GmbH, 2011This work presents results from the NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) study. Whole air samples were obtained on board research flights that flew over California during June 2008 and analyzed for selected volatile organic compounds, including several halogenated species. Samples collected over the South Coast Air Basin of California (SoCAB), which includes much of Los Angeles (LA) County, were compared with samples from inflow air masses over the Pacific Ocean. The levels of many halocarbon species were enhanced significantly over t ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Carrio G.G.; Cotton William R. - Copernicus GmbH, 2011This paper examines the feasibility of mitigating the intensity of hurricanes by enhancing the CCN concentrations in the outer rainband region. Increasing CCN concentrations would cause a reduced collision and coalescence, resulting in more supercooled liquid water to be transported aloft which then freezes and enhances convection via enhanced latent heat of freezing. The intensified convection would condense more water ultimately enhancing precipitation in the outer rainbands. Enhanced evaporative cooling from the increased precipitation in the outer rainbands would produce stronger and more ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Ebert M.; Worringen A.; Benker N.; et al. - Copernicus GmbH, 2011During an intensive campaign at the high alpine research station Jungfraujoch, Switzerland, in February/March 2006 ice particle residuals within mixed-phase clouds were sampled using the Ice-counterflow virtual impactor (Ice-CVI). Size, morphology, chemical composition, mineralogy and mixing state of the ice residual and the interstitial (i.e., non-activated) aerosol particles were analyzed by scanning and transmission electron microscopy. Ice nuclei (IN) were identified from the significant enrichment of particle groups in the ice residual (IR) samples relative to the interstitial aerosol. In ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Gilardoni S.; Vignati E.; Marmer E.; et al. - Copernicus GmbH, 2011The quantification of sources of carbonaceous aerosol is important to understand their atmospheric concentrations and regulating processes and to study possible effects on climate and air quality, in addition to develop mitigation strategies.
In the framework of the European Integrated Project on Aerosol Cloud Climate Interactions (EUCAARI) fine (DpPermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Wu D.L.; Chae J.H.; Lambert A.; et al. - Copernicus GmbH, 2011A research algorithm is developed for noise evaluation and feature detection of the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) Level 1 (L1) backscatter data with an emphasis on cloud/aerosol features in the upper troposphere and lower stratosphere (UT/LS). CALIOP measurement noise of the version v2.01 and v2.02 L1 backscatter data aggregated to (5 km) horizontal resolution is analyzed with two approaches in this study. One is to compare the observed and modeled molecular scatter profiles by scaling the modeled profile (with a fitted scaling factor α) to the observed clear-sky ba ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Fuentes E.; Coe H.; Green D.; et al. - Copernicus GmbH, 2011The effect of nanogel colloidal and dissolved organic matterPermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Rose D.; Gunthe S.S.; Su H.; et al. - Copernicus GmbH, 2011Size-resolved chemical composition, mixing state, and cloud condensation nucleus (CCN) activity of aerosol particles in polluted mega-city air and biomass burning smoke were measured during the PRIDE-PRD2006 campaign near Guangzhou, China, using an aerosol mass spectrometer (AMS), a volatility tandem differential mobility analyzer (VTDMA), and a continuous-flow CCN counter (DMT-CCNC).PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Slowik J.G.; Brook J.; Chang R.Y.-W.; et al. - Copernicus GmbH, 2011As part of the BAQS-Met 2007 field campaign, Aerodyne time-of-flight aerosol mass spectrometers (ToF-AMS) were deployed at two sites in southwestern Ontario from 17 June to 11 July 2007. One instrument was located at Harrow, ON, a rural, agriculture-dominated area approximately 40 km southeast of the Detroit/Windsor/Windsor urban area and 5 km north of Lake Erie. The second instrument was located at Bear Creek, ON, a rural site approximately 70 km northeast of the Harrow site and 50 km east of Detroit/Windsor. Positive matrix factorization analysis of the combined organic mass spectral dataset ...PermalinkAtmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Kuhn T.; Earle M.E.; Khalizov A.F.; et al. - Copernicus GmbH, 2011The relative roles of volume and surface nucleation were investigated for the homogeneous freezing of pure water droplets. Experiments were carried out in a cryogenic laminar aerosol flow tube using supercooled water aerosols with maximum volume densities at radii between 1 and 3 μm. Temperature- and size-dependent values of volume- and surface-based homogeneous nucleation rates between 234.8 and 236.2 K were derived using a microphysical model and aerosol phase compositions and size distributions determined from infrared extinction measurements in the flow tube. The results show that the cont ...Permalink