scholarly journals Profiling of Saharan dust from the Caribbean to western Africa – Part 1: Layering structures and optical properties from shipborne polarization/Raman lidar observations

2017 ◽  
Vol 17 (21) ◽  
pp. 12963-12983 ◽  
Author(s):  
Franziska Rittmeister ◽  
Albert Ansmann ◽  
Ronny Engelmann ◽  
Annett Skupin ◽  
Holger Baars ◽  
...  
Keyword(s):  
Optical Properties ◽  
Conceptual Model ◽  
Long Range Transport ◽  
Tropical Atlantic ◽  
Raman Lidar ◽  
Western Africa ◽  
Range Transport ◽  
Lidar Ratio ◽  
The Caribbean ◽  
Lidar Observations

Abstract. We present final and quality-assured results of multiwavelength polarization/Raman lidar observations of the Saharan air layer (SAL) over the tropical Atlantic. Observations were performed aboard the German research vessel R/V Meteor during the 1-month transatlantic cruise from Guadeloupe to Cabo Verde over 4500 km from 61.5 to 20° W at 14–15° N in April–May 2013. First results of the shipborne lidar measurements, conducted in the framework of SALTRACE (Saharan Aerosol Long-range Transport and Aerosol–Cloud Interaction Experiment), were reported by Kanitz et al.(2014). Here, we present four observational cases representing key stages of the SAL evolution between Africa and the Caribbean in detail in terms of layering structures and optical properties of the mixture of predominantly dust and aged smoke in the SAL. We discuss to what extent the lidar results confirm the validity of the SAL conceptual model which describes the dust long-range transport and removal processes over the tropical Atlantic. Our observations of a clean marine aerosol layer (MAL, layer from the surface to the SAL base) confirm the conceptual model and suggest that the removal of dust from the MAL, below the SAL, is very efficient. However, the removal of dust from the SAL assumed in the conceptual model to be caused by gravitational settling in combination with large-scale subsidence is weaker than expected. To explain the observed homogenous (height-independent) dust optical properties from the SAL base to the SAL top, from the African coast to the Caribbean, we have to assume that the particle sedimentation strength is reduced and dust vertical mixing and upward transport mechanisms must be active in the SAL. Based on lidar observations on 20 nights at different longitudes in May 2013, we found, on average, MAL and SAL layer mean values (at 532 nm) of the extinction-to-backscatter ratio (lidar ratio) of 17±5 sr (MAL) and 43±8 sr (SAL), of the particle linear depolarization ratio of 0.025±0.015 (MAL) and 0.19±0.09 (SAL), and of the particle extinction coefficient of 67±45 Mm−1 (MAL) and 68±37 Mm−1 (SAL). The 532 nm optical depth of the lofted SAL was found to be, on average, 0.15±0.13 during the ship cruise. The comparably low values of the SAL mean lidar ratio and depolarization ratio (compared to typical pure dust values of 50–60 sr and 0.3, respectively) in combination with backward trajectories indicate a smoke contribution to light extinction of the order of 20 % during May 2013, at the end of the burning season in central-western Africa.

scholarly journals CALIPSO lidar observations of the optical properties of Saharan dust: A case study of long-range transport

2008 ◽  
Vol 113 (D7) ◽  
Author(s):  
Zhaoyan Liu ◽  
Ali Omar ◽  
Mark Vaughan ◽  
Johnathan Hair ◽  
Chieko Kittaka ◽  
...  
Keyword(s):  
Optical Properties ◽  
Long Range ◽  
Saharan Dust ◽  
Long Range Transport ◽  
Range Transport ◽  
Lidar Observations

scholarly journals Vertical aerosol distribution in the Southern hemispheric Midlatitudes as observed with lidar at Punta Arenas, Chile (53.2° S and 70.9° W) during ALPACA

2018 ◽  
Author(s):  
Andreas Foth ◽  
Thomas Kanitz ◽  
Ronny Engelmann ◽  
Holger Baars ◽  
Martin Radenz ◽  
...  
Keyword(s):  
Long Range Transport ◽  
Free Troposphere ◽  
Marine Aerosol ◽  
Raman Lidar ◽  
Aerosol Distribution ◽  
Range Transport ◽  
Aerosol Sources ◽  
Ground Based Lidar ◽  
Lidar Observations ◽  
Measurement Period

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.

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

2017 ◽  
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).

scholarly journals Retrieval of Dust Microphysical Properties

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.

scholarly journals Spectral optical properties of long-range transport Asian dust and pollution aerosols over Northeast Asia in 2007 and 2008

2010 ◽  
Vol 10 (12) ◽  
pp. 5391-5408 ◽  
Author(s):  
J. Jung ◽  
Y. J. Kim ◽  
K. Y. Lee ◽  
M. G. -Cayetano ◽  
T. Batmunkh ◽  
...  
Keyword(s):  
Optical Properties ◽  
Long Range ◽  
Atmospheric Chemistry ◽  
Light Attenuation ◽  
Measurement Data ◽  
Absorption Efficiency ◽  
Asian Dust ◽  
Urban Site ◽  
Long Range Transport ◽  
Range Transport

Abstract. As a part of the IGAC (International Global Atmospheric Chemistry) Mega-cities program, aerosol physical and optical properties were continuously measured from March 2007 to March 2008 at an urban site (37.57° N, 126.94° E) in Seoul, Korea. Spectral optical properties of long-range transported Asian dust and pollution aerosols have been investigated based on the year long measurement data. Optically measured black carbon/thermally measured elemental carbon (BC/EC) ratio showed clear monthly variation with high values in summer and low values in winter mainly due to the enhancement of light attenuation by the internal mixing of EC. Novel approach has been suggested to retrieve the spectral light absorption coefficient (babs) from Aethalometer raw data by using BC/EC ratio. Mass absorption efficiency, σabs (=babs/EC) at 550 nm was determined to be 9.0±1.3, 8.9±1.5, 9.5±2.0, and 10.3±1.7 m2 g−1 in spring, summer, fall, and winter, respectively with an annual mean of 9.4±1.8 m2 g−1. Threshold values to classify severe haze events were suggested in this study. Increasing trend of aerosol single scattering albedo (SSA) with wavelength was observed during Asian dust events while little spectral dependence of SSA was observed during long-range transport pollution (LTP) events. Satellite aerosol optical thickness (AOT) and Hysplit air mass backward trajectory analyses as well as chemical analysis were performed to characterize the dependence of spectral optical properties on aerosol type. Results from this study can provide useful information for studies on regional air quality and aerosol's effects on climate change.

scholarly journals Insights into the aging of biomass burning aerosol from satellite observations and 3D atmospheric modeling: evolution of the aerosol optical properties in Siberian wildfire plumes

2021 ◽  
Vol 21 (1) ◽  
pp. 357-392
Author(s):  
Igor B. Konovalov ◽  
Nikolai A. Golovushkin ◽  
Matthias Beekmann ◽  
Meinrat O. Andreae
Keyword(s):  
Optical Properties ◽  
Long Range ◽  
Biomass Burning ◽  
Organic Aerosol ◽  
Satellite Observations ◽  
Long Range Transport ◽  
Aerosol Optical Properties ◽  
Smoke Plumes ◽  
Range Transport ◽  
Aerosol Aging

Abstract. Long-range transport of biomass burning (BB) aerosol from regions affected by wildfires is known to have a significant impact on the radiative balance and air quality in receptor regions. However, the changes that occur in the optical properties of BB aerosol during long-range transport events are insufficiently understood, limiting the adequacy of representations of the aerosol processes in chemistry transport and climate models. Here we introduce a framework to infer and interpret changes in the optical properties of BB aerosol from satellite observations of multiple BB plumes. Our framework includes (1) a procedure for analysis of available satellite retrievals of the absorption and extinction aerosol optical depths (AAOD and AOD) and single-scattering albedo (SSA) as a function of the BB aerosol photochemical age and (2) a representation of the AAOD and AOD evolution with a chemistry transport model (CTM) involving a simplified volatility basis set (VBS) scheme with a few adjustable parameters. We apply this framework to analyze a large-scale outflow of BB smoke plumes from Siberia toward Europe that occurred in July 2016. We use AAOD and SSA data derived from OMI (Ozone Monitoring Instrument) satellite measurements in the near-UV range along with 550 nm AOD and carbon monoxide (CO) columns retrieved from MODIS (Moderate Resolution Imaging Spectroradiometer) and IASI (Infrared Atmospheric Sounding Interferometer) satellite observations, respectively, to infer changes in the optical properties of Siberian BB aerosol due to its atmospheric aging and to get insights into the processes underlying these changes. Using the satellite data in combination with simulated data from the CHIMERE CTM, we evaluate the enhancement ratios (EnRs) that allow isolating AAOD and AOD changes due to oxidation and gas–particle partitioning processes from those due to other processes, including transport, deposition, and wet scavenging. The behavior of EnRs for AAOD and AOD is then characterized using nonlinear trend analysis. It is found that the EnR for AOD strongly increases (by about a factor of 2) during the first 20–30 h of the analyzed evolution period, whereas the EnR for AAOD does not exhibit a statistically significant increase during this period. The increase in AOD is accompanied by a statistically significant enhancement of SSA. Further BB aerosol aging (up to several days) is associated with a strong decrease in EnRs for both AAOD and AOD. Our VBS simulations constrained by the observations are found to be more consistent with satellite observations of strongly aged BB plumes than “tracer” simulations in which atmospheric transformations of BB organic aerosol were disregarded. The simulation results indicate that the upward trends in EnR for AOD and in SSA are mainly due to atmospheric processing of secondary organic aerosol (SOA), leading to an increase in the mass scattering efficiency of BB aerosol. Evaporation and chemical fragmentation of the SOA species, part of which is assumed to be absorptive (to contain brown carbon), are identified as likely reasons for the subsequent decrease in the EnR for both AAOD and AOD. Hence, our analysis reveals that the long-range transport of smoke plumes from Siberian fires is associated with major changes in BB aerosol optical properties and chemical composition. Overall, this study demonstrates the feasibility of using available satellite observations for evaluating and improving representations in atmospheric models of the BB aerosol aging processes in different regions of the world at much larger temporal scales than those typically addressed in aerosol chamber experiments.

scholarly journals 1064 nm rotational Raman lidar for particle extinction and lidar-ratio profiling: cirrus case study

2016 ◽  
Vol 9 (9) ◽  
pp. 4269-4278 ◽  
Author(s):  
Moritz Haarig ◽  
Ronny Engelmann ◽  
Albert Ansmann ◽  
Igor Veselovskii ◽  
David N. Whiteman ◽  
...  
Keyword(s):  
Good Accuracy ◽  
Lower Troposphere ◽  
Vertical Profiles ◽  
Raman Lidar ◽  
Extinction Coefficients ◽  
Lidar Ratio ◽  
Raman Backscatter ◽  
First Time ◽  
Lidar Observations

Abstract. For the first time, vertical profiles of the 1064 nm particle extinction coefficient obtained from Raman lidar observations at 1058 nm (nitrogen and oxygen rotational Raman backscatter) are presented. We applied the new technique in the framework of test measurements and performed several cirrus observations of particle backscatter and extinction coefficients, and corresponding extinction-to-backscatter ratios at the wavelengths of 355, 532, and 1064 nm. The cirrus backscatter coefficients were found to be equal for all three wavelengths keeping the retrieval uncertainties in mind. The multiple-scattering-corrected cirrus extinction coefficients at 355 nm were on average about 20–30 % lower than the ones for 532 and 1064 nm. The cirrus-mean extinction-to-backscatter ratio (lidar ratio) was 31 ± 5 sr (355 nm), 36 ± 5 sr (532 nm), and 38 ± 5 sr (1064 nm) in this single study. We further discussed the requirements needed to obtain aerosol extinction profiles in the lower troposphere at 1064 nm with good accuracy (20 % relative uncertainty) and appropriate temporal and vertical resolution.

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

2018 ◽  
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.

Aerosol optical properties at Mauna Loa Observatory: Long-range transport from Kuwait?

1992 ◽  
Vol 19 (6) ◽  
pp. 581-584 ◽  
Author(s):  
B. A. Bodhaine ◽  
J. M. Harris ◽  
J. A. Ogren ◽  
D. J. Hofmann
Keyword(s):  
Optical Properties ◽  
Long Range ◽  
Long Range Transport ◽  
Aerosol Optical Properties ◽  
Mauna Loa ◽  
Range Transport
Sign in / Sign up

Export Citation Format

Share Document