Multiwavelength Raman lidar observations of particle growth during long-range transport of forest-fire smoke in the free troposphere

Abstract. Within this publication, lidar observations of the vertical aerosol distribution above Punta Arenas, Chile (53.2° S and 50.9° W) which have been performed with the Raman lidar PollyXT from December 2009 to April 2010 are presented. Pristine marine aerosol conditions related to the prevailing westerly circulation dominated the measurements. Lofted aerosol layers could only be observed eight times during the whole measurement period. Two case studies are presented showing long-range transport of smoke from biomass burning in Australia and regionally transported dust from the Patagonian Desert, respectively. The aerosol sources are identified by trajectory analyses with HYSPLIT and FLEXPART. However, seven of the eight analysed cases with lofted layers show an aerosol optical thickness of less than 0.05. From the lidar observations a mean planetary boundary layer (PBL) top height of 1150 ± 350 m was determined. An analysis of particle backscatter coefficients confirms that the majority of the aerosol is attributed to the PBL while the free troposphere is characterized by a very low background aerosol concentration. The ground-based lidar observations at 532 and 1064 nm are supplemented by the AERONET Sun photometers and the space-borne lidar CALIOP on board of CALIPSO. The averaged AOT determined by CALIOP was 0.02 ± 0.01 at Punta Arenas from 2009 to 2010.

Download Full-text

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).

Download Full-text

Airborne lidar observations of long-range transport in the free troposphere

Environmental Science & Technology ◽

10.1021/es00128a006 ◽

1984 ◽

Vol 18 (10) ◽

pp. 749-756 ◽

Cited By ~ 8

Author(s):

Scott T. Shipley ◽

Edward V. Browell ◽

David S. McDougal ◽

Brian L. Orndorff ◽

Philip. Haagenson

Keyword(s):

Long Range ◽

Airborne Lidar ◽

Long Range Transport ◽

Free Troposphere ◽

Range Transport ◽

Lidar Observations

Download Full-text

On cases of anomalous (eastern) long-range transport of forest fire smoke

10.5194/acp-2017-1181-sc1 ◽

2018 ◽

Author(s):

Anonymous

Keyword(s):

Long Range ◽

Forest Fire ◽

Long Range Transport ◽

Fire Smoke ◽

Range Transport

Download Full-text

Analysis of aircraft and satellite measurements from the Intercontinental Chemical Transport Experiment (INTEX-B) to quantify long-range transport of East Asian sulfur to Canada

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-2999-2008 ◽

2008 ◽

Vol 8 (11) ◽

pp. 2999-3014 ◽

Cited By ~ 225

Author(s):

A. van Donkelaar ◽

R. V. Martin ◽

W. R. Leaitch ◽

A. M. Macdonald ◽

T. W. Walker ◽

...

Keyword(s):

British Columbia ◽

North America ◽

Long Range ◽

East Asian ◽

Chemical Transport ◽

Long Range Transport ◽

Free Troposphere ◽

Range Transport ◽

Transport Experiment ◽

Sulfur Emissions

Abstract. We interpret a suite of satellite, aircraft, and ground-based measurements over the North Pacific Ocean and western North America during April–May 2006 as part of the Intercontinental Chemical Transport Experiment Phase B (INTEX-B) campaign to understand the implications of long-range transport of East Asian emissions to North America. The Canadian component of INTEX-B included 33 vertical profiles from a Cessna 207 aircraft equipped with an aerosol mass spectrometer. Long-range transport of organic aerosols was insignificant, contrary to expectations. Measured sulfate plumes in the free troposphere over British Columbia exceeded 2 μg/m3. We update the global anthropogenic emission inventory in a chemical transport model (GEOS-Chem) and use it to interpret the observations. Aerosol Optical Depth (AOD) retrieved from two satellite instruments (MISR and MODIS) for 2000–2006 are analyzed with GEOS-Chem to estimate an annual growth in Chinese sulfur emissions of 6.2% and 9.6%, respectively. Analysis of aircraft sulfate measurements from the NASA DC-8 over the central Pacific, the NSF C-130 over the east Pacific and the Cessna over British Columbia indicates most Asian sulfate over the ocean is in the lower free troposphere (800–600 hPa), with a decrease in pressure toward land due to orographic effects. We calculate that 56% of the measured sulfate between 500–900 hPa over British Columbia is due to East Asian sources. We find evidence of a 72–85% increase in the relative contribution of East Asian sulfate to the total burden in spring off the northwest coast of the United States since 1985. Campaign-average simulations indicate anthropogenic East Asian sulfur emissions increase mean springtime sulfate in Western Canada at the surface by 0.31 μg/m3 (~30%) and account for 50% of the overall regional sulfate burden between 1 and 5 km. Mean measured daily surface sulfate concentrations taken in the Vancouver area increase by 0.32 μg/m3 per 10% increase in the simulated fraction of Asian sulfate, and suggest current East Asian emissions episodically degrade local air quality by more than 1.5 μg/m3.

Download Full-text

Transport of Canadian forest fire smoke over the UK as observed by lidar

10.5194/acp-2017-1181 ◽

2018 ◽

Cited By ~ 1

Author(s):

Geraint Vaughan ◽

Adam P. Draude ◽

Hugo M. A. Ricketts ◽

David M. Schultz ◽

Mariana Adam ◽

...

Keyword(s):

Forest Fire ◽

Forest Fires ◽

Western Canada ◽

North West ◽

Fire Smoke ◽

Range Transport ◽

Lidar Ratio ◽

The Uk ◽

Lidar Observations ◽

Aerosol Properties

Abstract. Layers of aerosol at heights between 2 and 11 km were observed with Raman lidars in the UK between 23 and 31 May 2016. A network of such lidars, supported by ceilometer observations, is used to map the extent of the aerosol and its optical properties. Spaceborne lidar profiles show that the aerosol originated from forest fires over Western Canada around 17 May, and indeed the aerosol properties – weak depolarisation and a lidar ratio at 355 nm in the range 35–65 sr – were consistent with long-range transport of forest fire smoke. The event was unusual in its persistence – the smoke plume was drawn into an atmospheric block that kept it above North-west Europe for nine days. Lidar observations show how the smoke layers became optically thinner during this period, but the lidar ratio and aerosol depolarisation showed little change.

Download Full-text

Aerosol content survey by mini N2-Raman lidar: Application to local and long-range transport aerosols

Atmospheric Environment ◽

10.1016/j.atmosenv.2010.11.001 ◽

2011 ◽

Vol 45 (39) ◽

pp. 7487-7495 ◽

Cited By ~ 29

Author(s):

Philippe Royer ◽

Patrick Chazette ◽

Melody Lardier ◽

Laurent Sauvage

Keyword(s):

Long Range ◽

Long Range Transport ◽

Raman Lidar ◽

Range Transport

Download Full-text

Analysis of aircraft and satellite measurements from the intercontinental chemical transport experiment (INTEX-B) to quantify long-range transport of East Asian Sulfur to Canada

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-8-4017-2008 ◽

2008 ◽

Vol 8 (1) ◽

pp. 4017-4057 ◽

Cited By ~ 3

Author(s):

A. van Donkelaar ◽

R. V. Martin ◽

W. R. Leaitch ◽

A. M. Macdonald ◽

T. W. Walker ◽

...

Keyword(s):

British Columbia ◽

North America ◽

Long Range ◽

East Asian ◽

Chemical Transport ◽

Long Range Transport ◽

Free Troposphere ◽

Range Transport ◽

Transport Experiment ◽

Sulfur Emissions

Abstract. We interpret a suite of satellite, aircraft, and ground-based measurements over the North Pacific Ocean and western North America during April–May 2006 as part of the Intercontinental Chemical Transport Experiment Phase B (INTEX-B) campaign to understand the implications of long-range transport of East Asian emissions to North America. The Canadian component of INTEX-B included 33 vertical profiles from a Cessna 207 aircraft equipped with an aerosol mass spectrometer. Long-range transport of organic aerosols was insignificant. Measured sulfate plumes in the free troposphere over British Columbia exceeded 1 μg/m3. We update the global anthropogenic emission inventory in a chemical transport model (GEOS-Chem) and use it to interpret the observations. Trends in Aerosol Optical Depth (AOD) retrieved from two satellite instruments (MISR and MODIS) for 2000–2006 are analyzed with GEOS-Chem to estimate an annual growth in Chinese sulfur emissions of 6.2% and 9.6%, respectively. Analysis of aircraft sulfate measurements from the NASA DC-8 over the central Pacific, the NSF C-130 over the east Pacific and the Cessna over British Columbia indicates most Asian sulfate over the ocean is in the lower free troposphere (800–600 hPa), with a decrease in pressure toward land due to orographic effects. We calculate that 63% of the measured sulfate at 600 hPa over British Columbia is due to East Asian sources. Simulation of INTEX-B and May 1985 aircraft measurements off the northwest coast of the United States reveals a 2.4–3.4 fold increase in the relative contribution of East Asian sulfate to the total burden. Campaign-average simulations indicate anthropogenic East Asian sulfur emissions increase mean springtime sulfate in Western Canada at the surface by 0.14–0.19 μg/m3 (~30%) and account for 40% of the overall regional sulfate burden between 1 and 5 km. Mean measured daily surface sulfate concentrations taken in the Vancouver area increase by 0.27 μg/m3 per 10% increase in the simulated fraction of Asian sulfate, suggesting current East Asian emissions degrade local air quality.

Download Full-text

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

10.5194/acp-2020-459 ◽

2020 ◽

Author(s):

Stefanos Samaras ◽

Christine Böckmann ◽

Moritz Haarig ◽

Albert Ansmann ◽

Adrian Walser ◽

...

Keyword(s):

Long Range ◽

Software Tool ◽

Total Surface Area ◽

Saharan Dust ◽

Radiation Budget ◽

Dust Particles ◽

Long Range Transport ◽

Raman Lidar ◽

Microphysical Properties ◽

Range Transport

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.

Download Full-text