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Characteristics of CALIOP attenuated backscatter noise: implication for cloud/aerosol detection
Atmospheric 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 ...
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Dry deposition of reactive nitrogen to European ecosystems: a comparison of inferential models across the NitroEurope network
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Flechard C.R.; Nemitz E.; Smith R.I.; et al. - Copernicus GmbH, 2011Inferential models have long been used to determine pollutant dry deposition to ecosystems from measurements of air concentrations and as part of national and regional atmospheric chemistry and transport models, and yet models still suffer very large uncertainties. An inferential network of 55 sites throughout Europe for atmospheric reactive nitrogen (Nr) was established in 2007, providing ambient concentrations of gaseous NH3, NO2, HNO3 and HONO and aerosol NH4+ and NO3− as part of the NitroEurope Integrated Project.
Network results providing modelled inorganic Nr dry deposition ...
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On the impacts of phytoplankton-derived organic matter on the properties of the primary marine aerosol – Part 2: Composition, hygroscopicity and cloud condensation activity
Atmospheric 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 matter <0.2 μm, secreted by marine biota, on the hygroscopic growth and droplet activation behaviour of the primary marine aerosol was studied. Seawater proxies were prepared by the combination of artificial seawater devoid of marine organics and natural seawater enriched in organic exudate released by laboratory-grown phytoplankton cultures, as described in a companion paper. The primary aerosol was produced by bubble bursting, using a plunging multijet system as an aerosol generator.
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Cloud condensation nuclei in polluted air and biomass burning smoke near the mega-city Guangzhou, China – Part 2: Size-resolved aerosol chemical composition, diurnal cycles, and externally mixed weakly CCN-active soot particles
Atmospheric 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).
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Photochemical processing of organic aerosol at nearby continental sites: contrast between urban plumes and regional aerosol
Atmospheric 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 ...
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Concurrent observations of atomic iodine, molecular iodine and ultrafine particles in a coastal environment
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Mahajan A.S.; Sorribas M.; Gómez Martín J.C.; et al. - Copernicus GmbH, 2011Simultaneous measurements of atomic iodine (I), molecular iodine (I2) and ultrafine particles were made at O Grove, Galicia (42.50° N, 8.87° W), on the northwest coast of Spain. The observations show a strong tidal signature, and indicate that the most probable sources of reactive iodine species are the exposed macroalgae during low tide. For the first time, I2 and I were concurrently measured revealing a high average I2/I ratio of ~32, which is higher than previously inferred by modelling studies. A 1-dimensional photochemical model is employed to simulate the observations showing that the hi ...
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The effect of H2SO4 – amine clustering on chemical ionization mass spectrometry (CIMS) measurements of gas-phase sulfuric acid
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Kurtén T.; Petäjä T.; Smith J.; et al. - Copernicus GmbH, 2011The state-of-the art method for measuring atmospheric gas-phase sulfuric acid is chemical ionization mass spectrometry (CIMS) based on nitrate reagent ions. We have assessed the possible effect of the sulfuric acid molecules clustering with base molecules on CIMS measurements using computational chemistry. From the computational data, three conclusions can be drawn. First, a significant fraction of the gas-phase sulfuric acid molecules are very likely clustered with amines if the amine concentration is around or above a few ppt. Second, some fraction of these acid-amine clusters may not be cha ...
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Origin and radiative forcing of black carbon transported to the Himalayas and Tibetan Plateau
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Kopacz M.; Mauzerall D.L.; Wang J.; et al. - Copernicus GmbH, 2011The remote and high elevation regions of central Asia are influenced by black carbon (BC) emissions from a variety of locations. BC deposition contributes to melting of glaciers and questions exist, of both scientific and policy interest, as to the origin of the BC reaching the glaciers. We use the adjoint of the GEOS-Chem model to identify the location from which BC arriving at a variety of locations in the Himalayas and Tibetan Plateau originates. We then calculate its direct and snow-albedo radiative forcing. We analyze the seasonal variation in the origin of BC using an adjoint sensitivity ...
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Size dependence of volume and surface nucleation rates for homogeneous freezing of supercooled water droplets
Atmospheric 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 ...
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Comparison of ambient aerosol extinction coefficients obtained from in-situ, MAX-DOAS and LIDAR measurements at Cabauw
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Zieger P.; Weingartner E.; Henzing J.; et al. - Copernicus GmbH, 2011In the field, aerosol in-situ measurements are often performed under dry conditions (relative humidity RH<30–40%). Since ambient aerosol particles experience hygroscopic growth at enhanced RH, their microphysical and optical properties – especially the aerosol light scattering – are also strongly dependent on RH. The knowledge of this RH effect is of crucial importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements. Here, we will present results from a four-month campaign which took place in summer 2009 in Cabauw, The Netherlands. The aerosol ...
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Comparison of ambient aerosol extinction coefficients obtained from in-situ, MAX-DOAS and LIDAR measurements at Cabauw
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Zieger P.; Weingartner E.; Henzing J.; et al. - Copernicus GmbH, 2011In the field, aerosol in-situ measurements are often performed under dry conditions (relative humidity RH<30–40%). Since ambient aerosol particles experience hygroscopic growth at enhanced RH, their microphysical and optical properties – especially the aerosol light scattering – are also strongly dependent on RH. The knowledge of this RH effect is of crucial importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements. Here, we will present results from a four-month campaign which took place in summer 2009 in Cabauw, The Netherlands. The aerosol ...
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Origin and radiative forcing of black carbon transported to the Himalayas and Tibetan Plateau
Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Kopacz M.; Mauzerall D.L.; Wang J.; et al. - Copernicus GmbH, 2011The remote and high elevation regions of central Asia are influenced by black carbon (BC) emissions from a variety of locations. BC deposition contributes to melting of glaciers and questions exist, of both scientific and policy interest, as to the origin of the BC reaching the glaciers. We use the adjoint of the GEOS-Chem model to identify the location from which BC arriving at a variety of locations in the Himalayas and Tibetan Plateau originates. We then calculate its direct and snow-albedo radiative forcing. We analyze the seasonal variation in the origin of BC using an adjoint sensitivity ...
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Cumulative carbon emissions, emissions floors and short-term rates of warming: implications for policy
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 369. N° 1934. Bowerman Niel H.A.; Frame David J.; Huntingford Chris; et al. - The Royal Society, 2011A number of recent studies have found a strong link between peak human-induced global warming and cumulative carbon emissions from the start of the industrial revolution, while the link to emissions over shorter periods or in the years 2020 or 2050 is generally weaker. However, cumulative targets appear to conflict with the concept of a ‘floor’ in emissions caused by sectors such as food production. Here, we show that the introduction of emissions floors does not reduce the importance of cumulative emissions, but may make some warming targets unachievable. For pathways that give a most likely ...
The BioCarbon Fund Experience: insights from Afforestation/Reforestation Clean Development Mechanism Projects
The report is an effort to inform project developers and policy-makers about the main lessons learned by the BioCarbon Fund while accompanying the development of more than 20 A/R CDM forest projects in 16 countries since it started operations in 2004. It sheds light on opportunities the CDM offers to the forestry sector and also on the challenges encountered by project developers when complying with the regulatory requirements. The report concludes with recommendations for policy-makers on how current rules could be made more pragmatic to better match the realities of this type of projects on ...
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