Investigations of aerosol impacts on hurricanes: virtual seeding flights

Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Carrio G.G.; Cotton William R. - Copernicus GmbH, 2011

This 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 ...

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Investigations of aerosol impacts on hurricanes: virtual seeding flights

  Available online: http://dx.doi.org/10.5194/acp-11-2557-2011

G.G. Carrio ; William R. Cotton

in Atmospheric Chemistry and Physics (ACP) > Vol. 11. N° 3 [03/01/2011] . - p.2557-2567

This 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 widespread areal cold pools which block the flow of energy into the storm core, ultimately inhibiting the intensification of the tropical cyclone.
We designed a series of multi-grid for which the time of the "virtual flights" as well as the aerosol release rates are varied. A code that simulates the flight of a plane is used to increase the CCN concentrations as an aircraft flies. Results show a significant sensitivity to both the seeding time and the aerosol release rates and support the aforementioned hypothesis.

Language(s): English

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Tags: Aerosols ; Impact studies ; Hurricane ; Natural hazards ; United States of America Add tag

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Chemical composition and mixing-state of ice residuals sampled within mixed phase clouds

Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Ebert M.; Worringen A.; Benker N.; et al. - Copernicus GmbH, 2011

During 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 ...

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Chemical composition and mixing-state of ice residuals sampled within mixed phase clouds

  Available online: http://dx.doi.org/10.5194/acp-11-2805-2011

M. Ebert ; A. Worringen ; N. Benker ; S. Mertes ; E. Weingartner ; S. Weinbruch

in Atmospheric Chemistry and Physics (ACP) > Vol. 11. N° 3 [03/01/2011] . - p.2805-2816

During 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 terms of number lead-bearing particles are enriched by a factor of approximately 25, complex internal mixtures with silicates or metal oxides as major components by a factor of 11, and mixtures of secondary aerosol and carbonaceous material (C-O-S particles) by a factor of 2. Other particle groups (sulfates, sea salt, Ca-rich particles, external silicates) observed in the ice-residual samples cannot be assigned unambiguously as IN. Between 9 and 24% of all IR are Pb-bearing particles. Pb was found as major component in around 10% of these particles (PbO, PbCl2). In the other particles, Pb was found as some 100 nm sized agglomerates consisting of 3–8 nm sized primary particles (PbS, elemental Pb). C-O-S particles are present in the IR at an abundance of 17–27%. The soot component within these particles is strongly aged. Complex internal mixtures occur in the IR at an abundance of 9–15%. Most IN identified at the Jungfraujoch station are internal mixtures containing anthropogenic components (either as main or minor constituent), and it is concluded that admixture of the anthropogenic component is responsible for the increased IN efficiency within mixed phase clouds. The mixing state appears to be a key parameter for the ice nucleation behaviour that cannot be predicted from the sole knowledge of the main component of an individual particle.

Language(s): English

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Tags: Aerosols ; Atmosphere ; Glaciology ; Cloud ; Observations ; Air pollution ; Alps, the ; Region VI - Europe Add tag

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Sources of carbonaceous aerosol in the Amazon basin

Atmospheric Chemistry and Physics (ACP), Vol. 11. N° 3. Gilardoni S.; Vignati E.; Marmer E.; et al. - Copernicus GmbH, 2011

The 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 (Dp < 2.5 μm) and coarse (2.5 μm < Dp <10 μm) aerosol particles were sampled from February to June (wet season) and from August to September (dry season) 2008 in the central Amazon basin. The mass of fine particles averaged 2.4 μg m−3 duri ...

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Sources of carbonaceous aerosol in the Amazon basin

  Available online: http://dx.doi.org/10.5194/acp-11-2747-2011

S. Gilardoni ; E. Vignati ; E. Marmer ; F. Cavalli ; C. Belis ; V. Gianelle ; A. Loureiro ; P. Artaxo

in Atmospheric Chemistry and Physics (ACP) > Vol. 11. N° 3 [03/01/2011] . - p.2747-2764

The 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 (Dp < 2.5 μm) and coarse (2.5 μm < Dp <10 μm) aerosol particles were sampled from February to June (wet season) and from August to September (dry season) 2008 in the central Amazon basin. The mass of fine particles averaged 2.4 μg m−3 during the wet season and 4.2 μg m−3 during the dry season. The average coarse aerosol mass concentration during wet and dry periods was 7.9 and 7.6 μg m−3, respectively. The overall chemical composition of fine and coarse mass did not show any seasonality with the largest fraction of fine and coarse aerosol mass explained by organic carbon (OC); the average OC to mass ratio was 0.4 and 0.6 in fine and coarse aerosol modes, respectively. The mass absorbing cross section of soot was determined by comparison of elemental carbon and light absorption coefficient measurements and it was equal to 4.7 m2 g−1 at 637 nm. Carbon aerosol sources were identified by Positive Matrix Factorization (PMF) analysis of thermograms: 44% of fine total carbon mass was assigned to biomass burning, 43% to secondary organic aerosol (SOA), and 13% to volatile species that are difficult to apportion. In the coarse mode, primary biogenic aerosol particles (PBAP) dominated the carbonaceous aerosol mass. The results confirmed the importance of PBAP in forested areas.

The source apportionment results were employed to evaluate the ability of global chemistry transport models to simulate carbonaceous aerosol sources in a regional tropical background site. The comparison showed an overestimation of elemental carbon (EC) by the TM5 model during the dry season and OC both during the dry and wet periods. The overestimation was likely due to the overestimation of biomass burning emission inventories and SOA production over tropical areas.

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Tags: Aerosols ; Amazon ; Carbon dioxide (CO2) ; Observations ; Air quality ; Region III - South America Add tag

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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, 2011

A 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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Characteristics of CALIOP attenuated backscatter noise: implication for cloud/aerosol detection

  Available online: http://dx.doi.org/10.5194/acp-11-2641-2011

D.L. Wu ; J.H. Chae ; A. Lambert ; F.F. Zhang

in Atmospheric Chemistry and Physics (ACP) > Vol. 11. N° 3 [03/01/2011] . - p.2641-2654

A 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 backscatter profiles. This scaling α value is sensitive to errors in the calibrated backscatter and the atmospheric model used. Most of the nighttime 532-nm α values are close to unity, as expected, but an abrupt drop occurred in October 2008 in the daytime 532-nm α, which is likely indicative of a problem in the v2.02 daytime calibrated data. The 1064-nm night α is generally close to 2 while its day α is ~3. The other approach to evaluate the lidar measurement noise is to use the calibrated lidar backscatter data at altitudes above 19 km. With this method, the 532-nm and 1064-nm measurement noises are analyzed and characterized individually for each profile in terms of the mean (μ) and standard deviation (σ), showing larger σ values in general over landmasses or bright surfaces during day and in radiation-hard regions during night. A significant increasing trend is evident in the nighttime 1064-nm σ, which is likely responsible for the increasing difference between the feature occurrence frequencies (532-nm vs. 1064-nm) derived from this study. For feature detection with the research algorithm, we apply a σ–based method to the aggregated L1 data. The derived morphology of feature occurrence frequency is in general agreement with that obtained from the Level 2 (L2) 05 km_CLAY+05 km_ALAY products at 5 km horizontal resolution. Finally, a normalized probability density function (PDF) method is employed to evaluate the day-night backscatter data in which noise levels are largely different. CALIOP observations reveal a higher probability of daytime cloud/aerosol occurrence than nighttime in the tropical UT/LS region for 532-nm total backscatters >0.01 km−1 sr−1.

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Tags: Aerosols ; Atmosphere ; Observations ; Research Add tag

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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, 2011

The 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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On the impacts of phytoplankton-derived organic matter on the properties of the primary marine aerosol – Part 2: Composition, hygroscopicity and cloud condensation activity

  Available online: http://dx.doi.org/10.5194/acp-11-2585-2011

E. Fuentes ; H. Coe ; D. Green ; G. McFiggans

in Atmospheric Chemistry and Physics (ACP) > Vol. 11. N° 3 [03/01/2011] . - p.2585-2602

The 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.

Language(s): English

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Tags: Aerosols ; Ecosystem ; Environment and landscape ; Ocean-atmosphere interaction ; Cloud condensation nuclei (CCN) ; Oceans Add tag

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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, 2011

Size-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, 2011

As 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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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, 2011

The 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, 2011

In 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, 2011

In 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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GAW Report, 200. WMO/GAW Standard Operating Procedures for In-situ Measurements of Aerosol Mass Concentration, Light Scattering and Light Absorption

World Meteorological Organization (WMO) - WMO, 2011

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Formation and Transport of Aerosols in Tokyo in Relation to Their Physical and Chemical Properties: a Review

Journal of the Meteorological Society of Japan, Vol. 88. No 4. Kondo Yutaka; Takegawa Nobuyuki; Matsui Hitoshi - Meteorological Society of Japan, 2010

Large amounts of reactive gases and aerosols are emitted from urban areas. Megacities, including the Tokyo Metropolitan Area (TMA), are very large, concentrated sources of these species affecting local, regional, and global ozone (O3) and aerosol levels. Emissions strongly influence air quality and climate on these scales. In 2003-2004, we made intensive measurements of O3 and chemical composition of aerosol particles with diameters less than 1 µm (PM1 aerosol) together with their precursors for the first time in Tokyo, Japan, as a part of the series of Integrated Measurement Program for Aeros ...

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Analysis of South Asian Monsoons within the Context of Increasing Regional Black Carbon Aerosols

Atmospheric and Oceanic Science Letters, Volume 3 Number 4. Mahmood Rashed; Yao Jin-Feng - Science Press, 2010

South Asian monsoons were analyzed within the context of increasing emissions of black carbon (BC) aerosols using a global atmospheric general circulation model. The BC aerosols were allowed to increase only over the south Asian domain to analyze the impacts of regional black carbon over the climatological patterns of monsoons. The black carbon significantly absorbed the incoming short wave radiation in the atmosphere, a result that is consistent with previous studies. Pre-monsoon (March-April-May) rainfall showed positive anomalies, particularly for some coastal regions of India. The summer ( ...

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Aerosol Indirect Effects on Warm Clouds in the Grid-Point Atmospheric Model of IAP LASG (GAMIL)

Atmospheric and Oceanic Science Letters, Volume 3 Number 4. Shi Xiang-Jun; Wang Bin; Liu Xiao-Hong; et al. - Science Press, 2010

Aerosol indirect effects on warm clouds are estimated in the Grid-point Atmospheric Model of IAP LASG (GAMIL) with a new two-moment cloud microphysics scheme using two different physically-based aerosol activation parameterizations: Abdul-Razzak and Ghan, and Nenes and Seinfeld. The annual global mean changes in shortwave cloud forcing from preindustrial times to present day (a measure of the aerosol indirect effects) estimated from these two parameterizations are remarkably similar: 0.76 W m-2 with the Abdul-Razzak and Ghan parameterization, and 0.78 W m-2 with the Nenes and Seinfeld paramete ...

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Volume 3 Number 4 - 16 July 2010

is an issue of Atmospheric and Oceanic Science Letters. Science Press, 2010

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