State of mixing, shape factor, number size distribution, and hygroscopic
                        growth of the Saharan anthropogenic and mineral dust aerosol at Tinfou,
                        Morocco

Kaaden, N.; Maßling, Andreas; Schladitz, A.; Müller, Thomas; Kandler, Konrad; Schütz, L.; Weinzierl, Bernadett; Petzold, A.; Tesche, Matthias; Leinert, S.; Deutscher, C.; Ebert, Martin; Weinbruch, Stephan; Wiedensohler, A.

doi:10.1111/j.1600-0889.2008.00388.x

Cited by 113 publications

(120 citation statements)

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“…Using the ground-based RH and a standard atmospheric model, it was estimated, within the range of altitudes where extinction peaks reached their maximum (2-3 km), that the positive bias due to humidity could reach up to 50 % in the case of urban aerosols. Ash being less hygroscopic than urban aerosols, as well as dust (Kaaden et al, 2008), the bias, although difficult to estimate, could be therefore much less important.…”

Section: Resultsmentioning

confidence: 99%

Detection and characterization of volcanic ash plumes over Lille during the Eyjafjallajökull eruption

et al. 2013

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Routine sun-photometer and micro-lidar measurements were performed in Lille, northern France, in April and May 2010 during the Eyjafjallajökull volcanic eruption. The impact of such an eruption emphasized significance of hazards for human activities and importance of observations of the volcanic aerosol particles. This paper presents the main results of a joint micro-lidar/sun-photometer analysis performed in Lille, where volcanic ash plumes were observed during at least 22 days, whenever weather conditions permitted. Aerosol properties retrieved from automatic sun-photometer measurements (AERONET) were strongly changed during the volcanic aerosol plumes transport over Lille. In most cases, the aerosol optical depth (AOD) increased, whereas Ångström exponent decreased, thus indicating coarse-mode dominance in the volume size distribution. Moreover, the non-spherical fraction retrieved by AERONET significantly increased. The real part of the complex refractive index was up to 1.55 at 440 nm during the eruption, compared to background data of about 1.46 before the eruption. Collocated lidar data revealed that several aerosol layers were present between 2 and 5 km, all originating from the Iceland region as confirmed by backward trajectories. The volcanic ash AOD was derived from lidar extinction profiles and sun-photometer AOD, and its maximum was estimated around 0.37 at 532 nm on 18 April 2010. This value was observed at an altitude of 1700 m and corresponds to an ash mass concentration (AMC) slightly higher than 1000 μg m⁻³ (±50%). An effective lidar ratio of ash particles of 48 sr was retrieved at 532 nm for 17 April during the early stages of the eruption, a value which agrees with several other studies carried out on this topic. Even though the accuracy of the retrievals is not as high as that obtained from reference multiwavelength lidar systems, this study demonstrates the opportunity of micro-lidar and sun-photometer joint data processing for deriving volcanic AMC. It also outlines the fact that a network of combined micro-lidars and sun photometers can be a powerful tool for routine monitoring of aerosols, especially in the case of such hazardous volcanic events

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Section: Resultsmentioning

confidence: 99%

Detection and characterization of volcanic ash plumes over Lille during the Eyjafjallajökull eruption

et al. 2013

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“…SEM analyses agree well with NanoSIMS results: during FCE 11.3, SEM analysis showed that 70-80 % of mineral dust particles in the 400-1000 nm size range acted as a cloud condensation nucleus (Sinha et al, 2014a). During FCE 11.2, no mineral dust was found with the SEM on the cloud droplet residual fine filter, so it is likely that fine mineral dust was unable to act as a cloud condensation nucleus, despite particle diameters as large as 600 nm, due to its hydrophobic nature (Kaaden et al, 2009). In all fine mineral dust in FCE 11.2 and between the upwind and interstitial in FCE 11.3, there is no significant change in δ 34 S (Fig.…”

Section: Mineral Dustmentioning

confidence: 95%

In-cloud sulfate addition to single particles resolved with sulfur isotope analysis during HCCT-2010

et al. 2014

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Abstract. In-cloud production of sulfate modifies aerosol size distribution, with important implications for the magnitude of indirect and direct aerosol cooling and the impact of SO 2 emissions on the environment. We investigate which sulfate sources dominate the in-cloud addition of sulfate to different particle classes as an air parcel passes through an orographic cloud. Sulfate aerosol, SO 2 and H 2 SO 4 were collected upwind, in-cloud and downwind of an orographic cloud for three cloud measurement events during the Hill Cap Cloud Thuringia campaign in autumn 2010 (HCCT-2010). Combined SEM and NanoSIMS analysis of single particles allowed the δ 34 S of particulate sulfate to be resolved for particle size and type.The most important in-cloud SO 2 oxidation pathway at HCCT-2010 was aqueous oxidation catalysed by transition metal ions (TMI catalysis), which was shown with single particle isotope analyses to occur primarily in cloud droplets nucleated on coarse mineral dust. In contrast, direct uptake of H 2 SO 4 (g) and ultrafine particulate were the most important sources modifying fine mineral dust, increasing its hygroscopicity and facilitating activation. Sulfate addition to "mixed" particles (secondary organic and inorganic aerosol) and coated soot was dominated by in-cloud aqueous SO 2 oxidation by H 2 O 2 and direct uptake of H 2 SO 4 (g) and ultrafine particle sulfate, depending on particle size mode and time of day. These results provide new insight into in-cloud sulfate production mechanisms, and show the importance of single particle measurements and models to accurately assess the environmental effects of cloud processing.

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“…Sahara dust particles measured previously at Cape Verde and in Morocco showed a specific dry mass between 2.45 and 2.7 g.cm −3 (Haywood et al, 2001;Kaaden et al, 2009). An average density of 2.5 g.cm −3 was employed here to calculate mass concentration and mass size distribution from the number distribution of GRIMM measurements.…”

Section: Grimm Field Calibrationmentioning

confidence: 99%

“…In the present study, we consider that dust is the prevailing component of the aerosol, making all calculations as if the aerosol is only formed by dust, as a valid approximation. Although desert dust particles are not truly spherical, presenting a Dynamic Shape Factor (χ) of around 1.25 (Kaaden et al, 2009), sphericity was used as an approximation in number to volume transformation. For comparison purposes, the dynamic shape factor for sodium chloride in the continuum regime is χ = 1.08 (Kelly and McMurry, 1992;Gysel et al, 2002).…”

Section: Grimm Field Calibrationmentioning

confidence: 99%

Seasonal variability of aerosol concentration and size distribution in Cape Verde using a continuous aerosol optical spectrometer

Pio

Cardoso

Cerqueira

et al. 2014

Front. Environ. Sci.

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One year of, almost continuous, measurements of aerosol optical properties and chemical composition were performed at the outskirts of Praia, Santiago Island, Cape Verde, within the framework of CV-DUST (Atmospheric aerosol in Cape Verde region: seasonal evaluation of composition, sources and transport) research project, during 2011. This article reports the aerosol number and mass concentration measurements using a GRIMM Optical Aerosol Spectrometer that provides number size discrimination into 31 size ranges from 0.25 to 32 μm. Time series of 5 min average PM 10 concentrations revealed peak values higher than 1000 μg.m −3 during winter dust storm events originating over Northern Africa. The 24 h average concentrations exceeded the World Health Organization (WHO) guidelines for PM 2.5 and PM 10 in 20 and 30% of the 2001 days, respectively. Annual average mass concentrations (±standard deviation) for PM 1 , PM 2.5 , and PM 10 were 5 ± 5, 19 ± 21, and 48 ± 64 μg.m −3 , respectively. The annual PM 2.5 and PM 10 values were also above the limits prescribed by the WHO (10 and 20 μg.m −3 , respectively). The aerosol mass size distribution revealed two main modes for particles smaller than 10 μm: a fine mode (0.7-0.8 μm), which possibly results of gas to particle conversion processes; and a coarse mode with maxima at 3-4 μm, which is associated with desert dust and sea salt sources. Within the coarse mode two sub-modes with maxima at 5-6 and 10-12 μm were frequently present.

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State of mixing, shape factor, number size distribution, and hygroscopic growth of the Saharan anthropogenic and mineral dust aerosol at Tinfou, Morocco

Cited by 113 publications

References 50 publications

Detection and characterization of volcanic ash plumes over Lille during the Eyjafjallajökull eruption

Detection and characterization of volcanic ash plumes over Lille during the Eyjafjallajökull eruption

In-cloud sulfate addition to single particles resolved with sulfur isotope analysis during HCCT-2010

Seasonal variability of aerosol concentration and size distribution in Cape Verde using a continuous aerosol optical spectrometer

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