Size distribution, chemical composition, and optical properties of urban and desert aerosols in Israel

Levin, Zev; Lindberg, James D.

doi:10.1029/jc084ic11p06941

Cited by 57 publications

(25 citation statements)

References 8 publications

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“…FN concentrations and AF values in the dust storm and clean conditions did not show a significant statistical difference (based on a t test). This suggests that dust particles are always present in the eastern Mediterranean atmosphere, even on days without dust storms, as was found by Levin and Lindberg (1979).…”

Section: Immersion-freezing Nuclei During Dust Storms and Clean Condisupporting

confidence: 55%

“…During the summer very few dust storms occur (Ganor et al, 1991). Although mineral dust particles are present in high concentrations during dust storms, such mineral dust particles are almost always present in the atmosphere in this region (Levin and Lindberg, 1979). Every year for one day during the month of May the eastern Mediterranean area is filled with biomass burning particles due to the Lag BaOmer (LBO) event.…”

Section: Characteristics Of the Research Areamentioning

confidence: 99%

“…Many of these air masses often contain aerosol particles from distant and local anthropogenic sources (Levin and Lindberg, 1979;Graham et al, 2004). Some contain dust particles from the Sahara (Ganor, 1994;Levin et al, 2005), while others contain marine and biogenic aerosol from the Mediterranean Sea (Levin et al, 1990) and from land sources (Ganor et al, 2000).…”

Section: Characteristics Of the Research Areamentioning

confidence: 99%

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Ground-based measurements of immersion freezing in the eastern Mediterranean

Ardon‐Dryer

Levin

2014

Atmos. Chem. Phys.

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Abstract. Ice nuclei were measured in immersion-freezing mode in the eastern Mediterranean region using the FRIDGE-TAU (FRankfurt Ice-nuclei Deposition freezinG Experiment, the Tel Aviv University version) chamber. Aerosol particles were sampled during dust storms and on clean and polluted days (e.g., Lag BaOmer). The aerosol immersion-freezing potential was analyzed in the laboratory using a drop-freezing method. Droplets from all the samples were found to freeze between −11.8 • C and −28.9 • C. Immersion-freezing nuclei (FN) concentrations range between 0.16 L −1 and 234 L −1 , while the activated fraction (AF) ranges between 8.7 × 10 −8 and 4.9 × 10 −4 . The median temperature at which the drops from each filter froze was found to be correlated with the corresponding daily average of PM 10 , PM 2.5 and PM 10 -PM 2.5 . A higher correlation value between FN concentrations and PM 10 -PM 2.5 suggests that the larger particles are generally more effective as FN.The measurements were divided into dust storms and "clean" conditions (this is a relative term, because dust particles are always present in the atmosphere is this region) based on the air mass back trajectories and the aerosol mass concentrations (PM 10 ). Droplets containing ambient particles from dust storm days froze at higher temperatures than droplets containing particles from clean days. Statistically significant differences were found between dust storms and clean conditions primarily in terms of the initial temperature at which the first drops froze, the median freezing temperature and the aerosol loading (PM values). FN concentrations and AF values in dust storms were larger by more than a factor of 2 than in the clean conditions. This observation agrees with previous studies showing that some dust particles are almost always present in the atmosphere in this region.Measurements of aerosol particles emitted from wood burning bonfires during a Lag BaOmer holiday showed that although a high concentration of particles was emitted, those particles' effectiveness as FN was relatively poor. The most likely reason for the low FN efficiency is the combination of relatively low fire temperatures and high organic carbon fraction in the aerosols.

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Section: Immersion-freezing Nuclei During Dust Storms and Clean Condisupporting

confidence: 55%

Section: Characteristics Of the Research Areamentioning

confidence: 99%

Section: Characteristics Of the Research Areamentioning

confidence: 99%

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Ground-based measurements of immersion freezing in the eastern Mediterranean

Ardon‐Dryer

Levin

2014

Atmos. Chem. Phys.

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“…8a have been found for all samples collected during the monitored dust events. A semi quantitative analysis of the relative abundance of the different elements with respect to Si has been carried out in all samples (Levin et al, 1979). Table 1 summarizes the X-ray count ratios of the different elements with respect to Si that have been obtained with 200 s counting time.…”

Section: X-ray Energy Dispersive Measurementsmentioning

confidence: 99%

Characterization of African dust over southern Italy

et al. 2003

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Abstract. Dust samples from rainfall residues have been collected in southeast Italy (40 • 20 N, 18 • 6 E) during dust outbreaks occurred from April to June 2002 to characterize morphological and elemental particle composition by different techniques, and investigate the dependence of particle properties on source regions. Four-day analytical back trajectories and satellite images have been used to infer source regions of the investigated dust samples.It has been found that the TOMS absorbing aerosol index was in the range 0.7-2.2 over Southern Italy when samples have been collected. The particle-size and -shape analysis by a scanning electron microscope (SEM) has revealed either that the particle-diameter distribution was between 0.3 and 30 µm with median-diameter values between 1.7-2.4 µm, and that the particles were characterized by a roundness factor varying from 0.8 to 2.5. The infrared transmission spectra have allowed recognizing that all dust samples contained a significant amount of illite. The X-ray energy dispersive (EDX) measurements have revealed that the Al/Si ratio of the transported dust varies from 0.41 to 0.50, and that the Al/Si,

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“…Its presence in the atmosphere even at the remotest locations was discovered in the 1970s and 1980s (Levin and Lindberg, 1979;Heintzenberg, 1982;Andreae, 1983), and the early studies on the environmental cycle of "black carbon" (BC) were summarized in the monograph Black Carbon in the Environment by E. D. Goldberg (1985). A recent review on the geochemistry of "black carbon" in the environment has been provided by Masiello (2004).…”

Section: Introductionmentioning

confidence: 99%

Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols

Andreae

Gelencsér²

2006

Atmos. Chem. Phys.

1,758

1,033

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Abstract. Although the definition and measurement techniques for atmospheric "black carbon" ("BC") or "elemental carbon'' ("EC") have long been subjects of scientific controversy, the recent discovery of light-absorbing carbon that is not black ("brown carbon, Cbrown") makes it imperative to reassess and redefine the components that make up light-absorbing carbonaceous matter (LAC) in the atmosphere. Evidence for the atmospheric presence of Cbrown comes from (1) spectral aerosol light absorption measurements near specific combustion sources, (2) observations of spectral properties of water extracts of continental aerosol, (3) laboratory studies indicating the formation of light-absorbing organic matter in the atmosphere, and (4) indirectly from the chemical analogy of aerosol species to colored natural humic substances. We show that brown carbon may severely bias measurements of "BC" and "EC" over vast parts of the troposphere, especially those strongly polluted by biomass burning, where the mass concentration of Cbrown is high relative to that of soot carbon. Chemical measurements to determine "EC" are biased by the refractory nature of Cbrown as well as by complex matrix interferences. Optical measurements of "BC" suffer from a number of problems: (1) many of the presently used instruments introduce a substantial bias into the determination of aerosol light absorption, (2) there is no unique conversion factor between light absorption and "EC" or "BC" concentration in ambient aerosols, and (3) the difference in spectral properties between the different types of LAC, as well as the chemical complexity of Cbrown, lead to several conceptual as well as practical complications. We also suggest that due to the sharply increasing absorption of Cbrown towards the UV, single-wavelength light absorption measurements may not be adequate for the assessment of absorption of solar radiation in the troposphere. We discuss the possible consequences of these effects for our understanding of tropospheric processes, including their influence on UV-irradiance, atmospheric photochemistry and radiative transfer in clouds.

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Size distribution, chemical composition, and optical properties of urban and desert aerosols in Israel

Cited by 57 publications

References 8 publications

Ground-based measurements of immersion freezing in the eastern Mediterranean

Ground-based measurements of immersion freezing in the eastern Mediterranean

Characterization of African dust over southern Italy

Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols

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