scholarly journals Development and evolution of an anomalous Asian dust event across Europe in March 2020

2021 ◽  
Author(s):  
Laura Tositti ◽  
Erika Brattich ◽  
Claudio Cassardo ◽  
Pietro Morozzi ◽  
Alessandro Bracci ◽  
...  
Keyword(s):  
Size Distribution ◽  
Mineral Dust ◽  
Dust Cloud ◽  
Back Trajectory ◽  
Composition Analysis ◽  
High Time Resolution ◽  
Sahara Desert ◽  
Dust Source ◽  
Number Size Distribution ◽  
Depth Analysis

Abstract. This paper concerns an in-depth analysis of an exceptional incursion of mineral dust over Southern Europe in late March 2020. This event was associated with an anomalous circulation pattern leading to several days of PM10 exceedances in connection with a dust source located in Central Asia a rare source of dust for Europe, more frequently affected by dust outbreaks from the Sahara desert. The synoptic meteorological configuration was analyzed in detail, while aerosol evolution during the transit of the dust cloud over Northern Italy was assessed at high time resolution by means of optical particle counting at three stations, namely Bologna, Trieste, and Mt. Cimone allowing to reveal transport timing among the three locations. Back-trajectory analyses supported by AOD (Aerosol Optical Depth) maps allowed to locate the mineral dust source area in the Aralkum region. The event was therefore analyzed through the observation of particle number size distribution with the support of chemical composition analysis. It is shown that PM10 exceedance recorded is associated with a large fraction of coarse particles in agreement with mineral dust properties. Both in-situ number size distribution and vertical distribution of the dust plume were cross-checked by Lidar Ceilometer and AOD data from two nearby stations, showing that the dust plume, differently from those originated in the Sahara desert, traveled close to the ground up to a height of about 2 km. The limited mixing layer height caused by high concentrations of absorbing and scattering aerosols caused the mixing of mineral dust with other locally-produced ambient aerosols, thereby potentially increasing its morbidity effects.

scholarly journals Using High Time Resolution Aerosol and Number Size Distribution Measurements to Estimate Atmospheric Extinction

2009 ◽  
Vol 59 (9) ◽  
pp. 1049-1060 ◽  
Author(s):  
William C. Malm ◽  
Gavin R. McMeeking ◽  
Sonia M. Kreidenweis ◽  
Ezra Levin ◽  
Christian M. Carrico ◽  
...  
Keyword(s):  
Size Distribution ◽  
Time Resolution ◽  
High Time ◽  
High Time Resolution ◽  
Atmospheric Extinction ◽  
Number Size Distribution

scholarly journals Airborne observations of mineral dust over Western Africa in the summer monsoon season: spatial and vertical variability of physico-chemical and optical properties

2011 ◽  
Vol 11 (1) ◽  
pp. 2549-2609 ◽  
Author(s):  
P. Formenti ◽  
J. L. Rajot ◽  
K. Desboeufs ◽  
F. Saïd ◽  
N. Grand ◽  
...  
Keyword(s):  
Optical Properties ◽  
Vertical Distribution ◽  
Size Distribution ◽  
Mineral Dust ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Airborne Measurements ◽  
Number Size Distribution ◽  
Western Africa ◽  
June July

Abstract. We performed airborne measurements of aerosol particle concentration, composition, size distribution and optical properties over Western Africa in the corridor 2–17° N and 3–5° E. Data were collected on board the French ATR-42 research aircraft in June–July 2006 as part of the African Monsoon Multidisciplinary Analysis (AMMA) intensive field phases in June–July 2006 using the AVIRAD airborne aerosol sampling system. The aerosol vertical distribution was documented on an almost daily basis. In particular, the vertical distribution of mineral dust emitted locally by Mesoscale Convective Systems (MSC) was distinguished from that of mineral dust that was transported from the Saharan by the African Easterly Jet (AEJ). Mineral dust emitted in the Sahel by convection-driven erosion was mostly confined in the boundary layer. One episode of injection of Sahelian mineral dust in the AEJ was observed. The single scattering albedo of Sahelian dust is lower than that of Saharan dust, owing to different mineralogy and size distribution. Nonetheless this difference is within 0.02 (single scattering albedo unit) and does not significantly alter the radiative perturbation at the surface or at the top of the atmosphere. Our investigation provides with further experimental evidence of the limited dynamical evolution of the number size distribution during two days of transport. Whereas the chemical composition is clearly depending on the origin of mineral dust, no indications are of a possible dependence on the number size distribution.

Number size distribution of particulate emissions of heavy-duty engines in real world test cycles

2003 ◽  
Vol 37 (37) ◽  
pp. 5247-5259 ◽  
Author(s):  
Urs Lehmann ◽  
Martin Mohr ◽  
Thomas Schweizer ◽  
Josef Rütter
Keyword(s):  
Size Distribution ◽  
Real World ◽  
Particulate Emissions ◽  
Heavy Duty ◽  
Number Size Distribution

scholarly journals Size-resolved and bulk activation properties of aerosols in the North China Plain

2011 ◽  
Vol 11 (8) ◽  
pp. 3835-3846 ◽  
Author(s):  
Z. Z. Deng ◽  
C. S. Zhao ◽  
N. Ma ◽  
P. F. Liu ◽  
L. Ran ◽  
...  
Keyword(s):  
Size Distribution ◽  
North China Plain ◽  
North China ◽  
Cloud Condensation Nuclei ◽  
Number Concentration ◽  
Anthropogenic Aerosol ◽  
Number Size Distribution ◽  
The North ◽  
The North China Plain ◽  
Activation Ratio

Abstract. Size-resolved and bulk activation properties of aerosols were measured at a regional/suburban site in the North China Plain (NCP), which is occasionally heavily polluted by anthropogenic aerosol particles and gases. A Cloud Condensation Nuclei (CCN) closure study is conducted with bulk CCN number concentration (NCCN) and calculated CCN number concentration based on the aerosol number size distribution and size-resolved activation properties. The observed CCN number concentration (NCCN-obs) are higher than those observed in other locations than China, with average NCCN-obs of roughly 2000, 3000, 6000, 10 000 and 13 000 cm−3 at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.70%, respectively. An inferred critical dry diameter (Dm) is calculated based on the NCCN-obs and aerosol number size distribution assuming homogeneous chemical composition. The inferred cut-off diameters are in the ranges of 190–280, 160–260, 95–180, 65–120 and 50–100 nm at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.7%, with their mean values 230.1, 198.4, 128.4, 86.4 and 69.2 nm, respectively. Size-resolved activation measurements show that most of the 300 nm particles are activated at the investigated supersaturations, while almost no particles of 30 nm are activated even at the highest supersaturation of 0.72%. The activation ratio increases with increasing supersaturation and particle size. The slopes of the activation curves for ambient aerosols are not as steep as those observed in calibrations with ammonium sulfate suggesting that the observed aerosols is an external mixture of more hygroscopic and hydrophobic particles. The calculated CCN number concentrations (NCCN-calc) based on the size-resolved activation ratio and aerosol number size distribution correlate well with the NCCN-obs, and show an average overestimation of 19%. Sensitivity studies of the CCN closure show that the NCCN at each supersaturation is well predicted with the campaign average of size-resolved activation curves. These results indicate that the aerosol number size distribution is critical in the prediction of possible CCN. The CCN number concentration can be reliably estimated using time-averaged, size-resolved activation efficiencies without accounting for the temporal variations.

scholarly journals Seasonal provenance changes in present-day Saharan dust collected in and off Mauritania

2017 ◽  
Vol 17 (16) ◽  
pp. 10163-10193 ◽  
Author(s):  
Carmen A. Friese ◽  
Johannes A. van Hateren ◽  
Christoph Vogt ◽  
Gerhard Fischer ◽  
Jan-Berend W. Stuut
Keyword(s):  
Environmental Changes ◽  
Saharan Dust ◽  
Local Source ◽  
Trade Wind ◽  
Back Trajectory ◽  
Dust Source ◽  
Western Sahara ◽  
Source Areas ◽  
Source Regions ◽  
Dust Sources

Abstract. Saharan dust has a crucial influence on the earth climate system and its emission, transport and deposition are intimately related to, e.g., wind speed, precipitation, temperature and vegetation cover. The alteration in the physical and chemical properties of Saharan dust due to environmental changes is often used to reconstruct the climate of the past. However, to better interpret possible climate changes the dust source regions need to be known. By analysing the mineralogical composition of transported or deposited dust, potential dust source areas can be inferred. Summer dust transport off northwest Africa occurs in the Saharan air layer (SAL). In continental dust source areas, dust is also transported in the SAL; however, the predominant dust input occurs from nearby dust sources with the low-level trade winds. Hence, the source regions and related mineralogical tracers differ with season and sampling location. To test this, dust collected in traps onshore and in oceanic sediment traps off Mauritania during 2013 to 2015 was analysed. Meteorological data, particle-size distributions, back-trajectory and mineralogical analyses were compared to derive the dust provenance and dispersal. For the onshore dust samples, the source regions varied according to the seasonal changes in trade-wind direction. Gibbsite and dolomite indicated a Western Saharan and local source during summer, while chlorite, serpentine and rutile indicated a source in Mauritania and Mali during winter. In contrast, for the samples that were collected offshore, dust sources varied according to the seasonal change in the dust transporting air layer. In summer, dust was transported in the SAL from Mauritania, Mali and Libya as indicated by ferroglaucophane and zeolite. In winter, dust was transported with the trades from Western Sahara as indicated by, e.g., fluellite.

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