Retrieval of microphysical dust particle properties from SALTRACE lidar observations: Case studies

Abstract. Saharan dust is a major natural atmospheric aerosol component with significant impact on the Earth radiation budget. In this work we determine the microphysical properties of dust particles after a long-range transport over the Atlantic Ocean, using input from three depolarization channels of a multi-wavelength polarization Raman lidar. The measurements were performed at Barbados in the framework of the Saharan Aerosol Long-Range Transport and Aerosol–Cloud-Interaction Experiment (SALTRACE) in the summers of 2013 and 2014. The microphysical retrievals are performed with the software tool SphInX (Spheroidal Inversion Experiments) which uses regularization for the inversion process and a new two-dimensional (2-D) extension of the Mie model approximating dust with spheroids. The method allows us to simultaneously retrieve shape- and size-dependent particle distributions. Because dust particles are mostly non-spherical this software tool fills the gap in estimating the non-spherical particle fraction. Two cases measured on 10 July 2013 and 20 June 2014 are discussed. 2-D radius-bimodal shape-size distribution are retrieved. The ratio of spherical-to-non-spherical contributions to the particle number concentration was found to be about 3/7. A volume-weighted effective aspect ratio of 1.1 was obtained, indicating slightly prolate particles. The total effective radius for the two cases in the preselected radius range from 0.01–2.2 μm was found to be, on average, 0.75 μm. The stronger dust event (10 July 2013) showed about 24 % higher values for the total surface-area and volume concentration. Finally, we compare our results with the ones from the polarization lidar-photometer networking (POLIPHON) method and ground-based photometers as well as with airborne in situ particle counters. Considering all differences in these independent approaches, we find a qualitatively good agreement between the different results and a consistent description of the dust cases. Such an extensive comparison is a novel and fruitful exercise and corroborates that the mathematical retrieval based on Raman lidar data of particle backscattering, extinction, and depolarization is a powerful tool even in the case of dust particles.

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From the Caribbean to West Africa: Four weeks of continuous dust and marine aerosol profiling with shipborne polarization/Raman lidar – a contribution to SALTRACE

10.5194/acp-2017-130 ◽

2017 ◽

Cited By ~ 3

Author(s):

Franziska Rittmeister ◽

Albert Ansmann ◽

Ronny Engelmann ◽

Annett Skupin ◽

Holger Baars ◽

...

Keyword(s):

Long Range ◽

Prediction Models ◽

Saharan Dust ◽

Dust Particles ◽

Research Vessel ◽

Long Range Transport ◽

Marine Aerosol ◽

Raman Lidar ◽

Range Transport ◽

Lidar Observations

Abstract. Continuous vertically resolved monitoring of marine aerosol, Saharan dust, and marine/dust aerosol mixtures was performed with multiwavelength polarization/Raman lidar aboard the German research vessel R/V Meteor during a one-month transatlantic cruise from Guadeloupe to Cabo Verde over 4500 km (from 61.5° W to 2&deg W, mostly along 14.5° N) in April–May 2013, as part of SALTRACE (Saharan Aerosol Long-range Transport and Aerosol–Cloud Interaction Experiment). An overview of measured aerosol optical properties over the tropical Atlantic is given in terms of spectrally resolved particle backscatter and extinction coefficients, lidar ratio, and linear depolarization ratio. Height profiles from the marine boundary layer (MBL) up to the top of the Saharan Air Layer (SAL) are presented. MBL and SAL mean lidar ratios were around 20 and 40 sr. These values indicate clean marine conditions in the MBL and entrainment of marine particles into the lower part of the SAL. In the central and upper parts of the SAL, the lidar ratios were most frequently 50–60 sr and thus typical for Saharan dust. The MBL and SAL mean depolarization ratios were close to 0.05 and between 0.2–0.3, respectively, which reflects almost dust-free conditions in the MBL and the occurrence of a mixture of marine and dust particles in the SAL. The conceptual model, describing the long-range transport and removal processes of Saharan dust over the North Atlantic, is discussed and confronted with the lidar observations along the west-to-east track of the slowly moving research vessel. The role of turbulent downward mixing as an efficient dust removal process is illuminated. In a follow-up article (Rittmeister et al., 2017), the lidar observations of dust extinction coefficient and derived mass concentration profiles are compared with respective dust profiles simulated with three well-established European atmospheric aerosol and dust prediction models (MACC, NMMB/BSC-Dust, SKIRON).

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Retrieval of Dust Microphysical Properties

EPJ Web of Conferences ◽

10.1051/epjconf/202023708019 ◽

2020 ◽

Vol 237 ◽

pp. 08019

Author(s):

Böckmann Christine ◽

Samaras Stefanos ◽

Haarig Moritz

Keyword(s):

Long Range ◽

Long Range Transport ◽

Raman Lidar ◽

Dust Event ◽

Lidar System ◽

Microphysical Properties ◽

Range Transport ◽

Multi Wavelength ◽

Lidar Ratio ◽

Analyze Data

An intense mineral dust event from the Saharan desert was observed over the Island of Barbados after a long-range transport over the Atlantic Ocean during SALTRACE Campaign in June 2014. We analyze data from a multi-wavelength Raman-lidar system of Leibniz Institute for Tropospheric Research (TROPOS) called BERTHA (Back- scatter Extinction lidar Ratio Temperature Humidity profiling Apparatus) to derive the aerosol microphysical properties of the inspected layer via regularization using the software SphInX (Spheroidal Inversion eXperiments). These parameters were found to be within credible ranges.

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Long range transport and mixing of aerosol sources during the 2013 North American biomass burning episode: analysis of multiple lidar observations in the Western Mediterranean basin

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-32323-2015 ◽

2015 ◽

Vol 15 (22) ◽

pp. 32323-32365 ◽

Cited By ~ 5

Author(s):

G. Ancellet ◽

J. Pelon ◽

J. Totems ◽

P. Chazette ◽

A. Bazureau ◽

...

Keyword(s):

Long Range ◽

Biomass Burning ◽

North American ◽

Western Mediterranean ◽

Saharan Dust ◽

Trade Wind ◽

Long Range Transport ◽

Range Transport ◽

Aerosol Sources ◽

Aerosol Source

Abstract. Long range transport of biomass burning (BB) aerosols between North America and the Mediterranean region took place in June 2013. A large number of ground based and airborne lidar measurements were deployed in the Western Mediterranean during the Chemistry-AeRosol Mediterranean EXperiment (ChArMEx) intensive observation period. A detailed analysis of the potential North American aerosol sources is conducted including the assessment of their transport to Europe using forward simulations of the FLEXPART Lagrangian particle dispersion model initialized using satellite observations by MODIS and CALIOP. The three dimensional structure of the aerosol distribution in the ChArMEx domain observed by the ground-based lidars (Menorca, Barcelona and Lampedusa), a Falcon-20 aircraft flight and three CALIOP tracks, agree very well with the model simulation of the three major sources considered in this work: Canadian and Colorado fires, a dust storm from Western US and the contribution of Saharan dust streamers advected from the North Atlantic trade wind region into the Westerlies region. Four aerosol types were identified using the optical properties of the observed aerosol layers (aerosol depolarization ratio, lidar ratio) and the transport model analysis of the contribution of each aerosol source: (I) pure BB layer, (II) weakly dusty BB, (III) significant mixture of BB and dust transported from the trade wind region (IV) the outflow of Saharan dust by the subtropical jet and not mixed with BB aerosol. The contribution of the Canadian fires is the major aerosol source during this episode while mixing of dust and BB is only significant at altitude above 5 km. The mixing corresponds to a 20–30 % dust contribution in the total aerosol backscatter. The comparison with the MODIS AOD horizontal distribution during this episode over the Western Mediterranean sea shows that the Canadian fires contribution were as large as the direct northward dust outflow from Sahara.

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Long-Range Transport of Saharan Dust to East Asia Observed with Lidars

SOLA ◽

10.2151/sola.2005-032 ◽

2005 ◽

Vol 1 ◽

pp. 121-124 ◽

Cited By ~ 13

Author(s):

Chan Bong Park ◽

Nobuo Sugimoto ◽

Ichiro Matsui ◽

Atsushi Shimizu ◽

Boyan Tatarov ◽

...

Keyword(s):

East Asia ◽

Long Range ◽

Saharan Dust ◽

Long Range Transport ◽

Range Transport

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Vertical Profiles of Aerosol Optical and Microphysical Properties During a Rare Case of Long-range Transport of Mixed Biomass Burning-polluted Dust Aerosols from the Russian Federation-kazakhstan to Athens, Greece

EPJ Web of Conferences ◽

10.1051/epjconf/201611918003 ◽

2016 ◽

Vol 119 ◽

pp. 18003 ◽

Cited By ~ 1

Author(s):

Alexandros Papayannis ◽

Athina Argyrouli ◽

Panayotis Kokkalis ◽

Georgios Tsaknakis ◽

Ioannis Binietoglou ◽

...

Keyword(s):

Long Range ◽

Russian Federation ◽

Biomass Burning ◽

Rare Case ◽

Long Range Transport ◽

Vertical Profiles ◽

Microphysical Properties ◽

Range Transport ◽

Mixed Biomass ◽

The Russian Federation

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Numerical simulations of windblown dust over complex terrain: The Fiambalá Basin episode in June 2015

10.5194/acp-2016-851 ◽

2016 ◽

Author(s):

Leonardo A. Mingari ◽

Estela A. Collini ◽

Arnau Folch ◽

Walter Báez ◽

Emilce Bustos ◽

...

Keyword(s):

Numerical Simulations ◽

Long Range ◽

Complex Terrain ◽

Volcanic Ash ◽

Dust Cloud ◽

Temporal Distribution ◽

Dust Particles ◽

Long Range Transport ◽

Mountain Range ◽

Range Transport

Abstract. On the 13 June 2015, the London Volcanic Ash Advisory Centre (VAAC) warned the Buenos Aires VAAC about a possible volcanic eruption from the Nevados Ojos del Salado volcano (6879 m), located in the Andes mountain range on the border between Chile and Argentina. A volcanic ash cloud was detected by the SEVIRI instrument on board the Meteosat Second Generation (MSG) satellites from 14:00 UTC on 13 June. Further studies concluded that the phenomenon was caused by remobilization of ancient pyroclastic deposits (circa 4.5 Ka Cerro Blanco eruption) from the Bolsón de Fiambalá (Fiambalá Basin) in northwestern Argentina. In this paper, we provide the first comprehensive description of the dust episode through observations and numerical simulations. We have investigated the spatio-temporal distribution of aerosols and the emission process over complex terrain to gain insight into the key role played by the orography and the condition that triggered the long-range transport episode. Numerical simulations of windblown dust were performed using the WRF-ARW/FALL3D modeling system with meteorological fields downscaled to a spatial resolution of 2 km in order to resolve the complex orography of the area. Results indicated that favourable conditions to generate dust uplifting occurred in northern Fiambalá Basin, where orographic effects caused strong surface winds. According to short-range numerical simulations, dust particles were confined to near-ground layers around the emission areas. On the other hand, dust aerosols were injected up to 5–6 km high in central and southern regions of the Fiambalá Basin, where intense ascending airflows are driven by horizontal convergence. Long-range transport numerical simulations were also performed to model dust cloud spreading over northern Argentina. Results of simulated vertical particle column mass were compared with the MSG-SEVIRI retrieval product. We tested two numerical schemes: with the default configuration of the FALL3D model, we found difficulties to simulate transport through orographic barriers, whereas an alternative configuration, using a numerical scheme to more accurately compute the horizontal advection in abrupt terrains, substantially improved the model performance.

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The OECD software tool for screening chemicals for persistence and long-range transport potential

Environmental Modelling & Software ◽

10.1016/j.envsoft.2008.06.014 ◽

2009 ◽

Vol 24 (2) ◽

pp. 228-237 ◽

Cited By ~ 89

Author(s):

Fabio Wegmann ◽

Laurent Cavin ◽

Matthew MacLeod ◽

Martin Scheringer ◽

Konrad Hungerbühler

Keyword(s):

Long Range ◽

Software Tool ◽

Long Range Transport ◽

Range Transport ◽

Transport Potential

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Long-range transport of Saharan dust and its radiative impact on precipitation forecast: a case study during the Convective and Orographically-induced Precipitation Study (COPS)

Quarterly Journal of the Royal Meteorological Society ◽

10.1002/qj.719 ◽

2011 ◽

Vol 137 (S1) ◽

pp. 236-251 ◽

Cited By ~ 47

Author(s):

Jean-Pierre Chaboureau ◽

Evelyne Richard ◽

Jean-Pierre Pinty ◽

Cyrille Flamant ◽

Paolo Di Girolamo ◽

...

Keyword(s):

Long Range ◽

Saharan Dust ◽

Precipitation Forecast ◽

Long Range Transport ◽

Radiative Impact ◽

Range Transport

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Long-Range Transport of Anthropogenically and Naturally Produced Particulate Matter in the Mediterranean and North Atlantic: Current State of Knowledge

Journal of Applied Meteorology and Climatology ◽

10.1175/jam2530.1 ◽

2007 ◽

Vol 46 (8) ◽

pp. 1230-1251 ◽

Cited By ~ 146

Author(s):

George Kallos ◽

Marina Astitha ◽

Petros Katsafados ◽

Chris Spyrou

Keyword(s):

Particulate Matter ◽

Air Quality ◽

North America ◽

Atlantic Ocean ◽

Long Range ◽

Saharan Dust ◽

Long Range Transport ◽

Transport And Transformation ◽

New Findings ◽

Range Transport

Abstract During the past 20 years, organized experimental campaigns as well as continuous development and implementation of air-pollution modeling have led to significant gains in the understanding of the paths and scales of pollutant transport and transformation in the greater Mediterranean region (GMR). The work presented in this paper has two major objectives: 1) to summarize the existing knowledge on the transport paths of particulate matter (PM) in the GMR and 2) to illustrate some new findings related to the transport and transformation properties of PM in the GMR. Findings from previous studies indicate that anthropogenically produced air pollutants from European sources can be transported over long distances, reaching Africa, the Atlantic Ocean, and North America. The PM of natural origin, like Saharan dust, can be transported toward the Atlantic Ocean and North America mostly during the warm period of the year. Recent model simulations and studies in the area indicate that specific long-range transport patterns of aerosols, such as the transport from Asia and the Indian Ocean, central Africa, or America, have negligible or at best limited contribution to air-quality degradation in the GMR when compared with the other sources. Also, new findings from this work suggest that the imposed European Union limits on PM cannot be applicable for southern Europe unless the origin (natural or anthropogenic) of the PM is taken into account. The impacts of high PM levels in the GMR are not limited only to air quality, but also include serious implications for the water budget and the regional climate. These are issues that require extensive investigation because the processes involved are complex, and further model development is needed to include the relevant physicochemical processes properly.

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