scholarly journals Analysis of a warehouse fire smoke plume over Paris with an N<sub>2</sub> Raman lidar and an optical thickness matching algorithm

2018 ◽  
Vol 11 (12) ◽  
pp. 6525-6538 ◽  
Author(s):  
Xiaoxia Shang ◽  
Patrick Chazette ◽  
Julien Totems
Keyword(s):  
Optical Thickness ◽  
Monte Carlo Algorithm ◽  
Optical Parameters ◽  
Depolarization Ratio ◽  
Raman Lidar ◽  
Smoke Plume ◽  
Paris Area ◽  
Fire Smoke ◽  
Lidar Ratio ◽  
Warehouse Fire

Abstract. A smoke plume, coming from an accidental fire in a textile warehouse in the north of Paris, covered a significant part of the Paris area on 17 April 2015 and seriously impacted the visibility over the megalopolis. This exceptional event was sampled with an automatic N2 Raman lidar, which operated 15 km south of Paris. The industrial pollution episode was concomitant with the long-range transport of dust aerosols originated from the Sahara, and with the presence of an extended stratus cloud cover. The analysis of the ground-based lidar profiles therefore required the development of an original inversion algorithm, using a top-down aerosol optical thickness matching (TDAM) approach. This study is, to the best of our knowledge, the first lidar measurement of a fresh smoke plume, emitted only a few hours after an accidental warehouse fire. Vertical profiles of the aerosol extinction coefficient, depolarization ratio, and lidar ratio are derived to optically characterize the aerosols that form the plume. We found a lidar ratio close to 50±10 sr for this fire smoke aerosol layer. The particle depolarization ratio is low, ∼1±0.1 %, suggesting the presence of either small particles or spherical hydrated aerosols in that layer. A Monte Carlo algorithm was used to assess the uncertainties on the optical parameters and to evaluate the TDAM algorithm.

scholarly journals Optical thickness matching algorithm applied to the case study of an accidental fire smoke plume over the Paris area with N<sub>2</sub>-Raman lidar

2018 ◽  
Author(s):  
Xiaoxia Shang ◽  
Patrick Chazette ◽  
Julien Totems
Keyword(s):  
Optical Thickness ◽  
Monte Carlo Algorithm ◽  
Spherical Particles ◽  
Optical Parameters ◽  
Aerosol Layer ◽  
Raman Lidar ◽  
Smoke Plume ◽  
Paris Area ◽  
Fire Smoke ◽  
Lidar Ratio

Abstract. A smoke plume, coming from an accidental fire in a textile warehouse in the north of Paris, covered a significant part of the Paris area on 17 April 2015 and seriously impacted the visibility over the megalopolis. This exceptional event was sampled with an automatic N2-Raman lidar, which operated 15 km south of Paris. The industrial pollution episode was concomitant with a long-range transport of dust aerosols raised from Sahara, and with the presence of an extended stratus cloud cover. The analysis of the ground-based lidar profiles therefore required the development of an original inversion algorithm, using a top-down aerosol optical thickness matching (TDAM) approach. This study is, to the best of our knowledge, the first lidar measurement of an accidental fire smoke plume. Vertical profiles of the aerosol extinction coefficient, depolarization and lidar ratio are derived to optically characterize the aerosols that form the plume. We found a lidar ratio close to 50 ± 10 sr for this fire smoke aerosol layer. The particle depolarization ratio is low, ~ 1 ± 0.1 %, suggesting the presence of spherical particles and therefore highly hydrated aerosols in that layer. A Monte Carlo algorithm was used to assess the uncertainties on the optical parameters, and to evaluate the TDAM algorithm.

scholarly journals Optical properties of an industrial fire observed with a ground based N2-Raman lidar over the Paris area

2018 ◽  
Vol 176 ◽  
pp. 04006
Author(s):  
Xiaoxia Shang ◽  
Patrick Chazette ◽  
Julien Totems
Keyword(s):  
Monte Carlo Algorithm ◽  
Optical Parameters ◽  
Lidar Measurement ◽  
Raman Lidar ◽  
Fire Plume ◽  
The North ◽  
Paris Area ◽  
Industrial Fire ◽  
Lidar Ratio ◽  
Aerosol Extinction Coefficient

This paper presents the first, to our knowledge, lidar measurement of an industrial fire plume, which covered the north of the Paris area on 17th April 2015. The fire started in a textile warehouse and rapidly spread by emitting large quantities of aerosols into the low troposphere. A ground based N2-Raman lidar performed continuous measurements during this event. Vertical profiles of the aerosol extinction coefficient, depolarization and lidar ratio are derived. A Monte Carlo algorithm was used to assess the uncertainties on the optical parameters, and to evaluate lidar inversion methods.

scholarly journals Forest Fire Smoke Layers Observed in the Free Troposphere over Portugal with a Multiwavelength Raman Lidar: Optical and Microphysical Properties

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Sérgio Nepomuceno Pereira ◽  
Jana Preißler ◽  
Juan Luis Guerrero-Rascado ◽  
Ana Maria Silva ◽  
Frank Wagner
Keyword(s):  
Single Scattering ◽  
Effective Radius ◽  
Free Troposphere ◽  
Depolarization Ratio ◽  
Raman Lidar ◽  
Extinction Coefficients ◽  
Smoke Particles ◽  
Microphysical Properties ◽  
Fire Smoke ◽  
Lidar Ratio

Vertically resolved optical and microphysical properties of biomass burning aerosols, measured in 2011 with a multiwavelength Raman lidar, are presented. The transportation time, within 1-2 days (or less), pointed towards the presence of relatively fresh smoke particles over the site. Some strong layers aloft were observed with particle backscatter and extinction coefficients (at 355 nm) greater than 5 Mm−1 sr−1and close to 300 Mm−1, respectively. The particle intensive optical properties showed features different from the ones reported for aged smoke, but rather consistent with fresh smoke. The Ångström exponents were generally high, mainly above 1.4, indicating a dominating accumulation mode. Weak depolarization values, as shown by the small depolarization ratio of 5% or lower, were measured. Furthermore, the lidar ratio presented no clear wavelength dependency. The inversion of the lidar signals provided a set of microphysical properties including particle effective radius below 0.2 μm, which is less than values previously observed for aged smoke particles. Real and imaginary parts of refractive index of about 1.5-1.6 and 0.02i, respectively, were derived. The single scattering albedo was in the range between 0.85 and 0.93; these last two quantities indicate the nonnegligible absorbing characteristics of the observed particles.

scholarly journals Optical and geometrical aerosol particle properties over the United Arab Emirates

2020 ◽  
Vol 20 (14) ◽  
pp. 8909-8922 ◽  
Author(s):  
Maria Filioglou ◽  
Elina Giannakaki ◽  
John Backman ◽  
Jutta Kesti ◽  
Anne Hirsikko ◽  
...  
Keyword(s):  
Aerosol Particle ◽  
United Arab Emirates ◽  
Mineral Dust ◽  
Depolarization Ratio ◽  
Raman Lidar ◽  
Particle Properties ◽  
Measurement Site ◽  
Ångström Exponent ◽  
Lidar Ratio ◽  
532 Nm

Abstract. One year of ground-based night-time Raman lidar observations has been analysed under the Optimization of Aerosol Seeding In rain enhancement Strategies (OASIS) project, in order to characterize the aerosol particle properties over a rural site in the United Arab Emirates. In total, 1130 aerosol particle layers were detected during the 1-year measurement campaign which took place between March 2018 and February 2019. Several subsequent aerosol layers could be observed simultaneously in the atmosphere up to 11 km. The observations indicate that the measurement site is a receptor of frequent dust events, but predominantly the dust is mixed with aerosols of anthropogenic and/or marine origin. The mean aerosol optical depth over the measurement site ranged at 0.37 ± 0.12 and 0.21 ± 0.11 for 355 and 532 nm, respectively. Moreover, mean lidar ratios of 43 ± 11 sr at a wavelength of 355 nm and 39 ± 10 sr at 532 nm were found. The average linear particle depolarization ratio measured over the course of the campaign was 15 ± 6 % and 19 ± 7 % at the 355 and 532 nm wavelengths, respectively. Since the region is both a source and a receptor of mineral dust, we have also explored the properties of Arabian mineral dust of the greater area of the United Arab of Emirates and the Arabian Peninsula. The observed Arabian dust particle properties were 45 ± 5 (42 ± 5) sr at 355 (532) nm for the lidar ratio, 25 ± 2 % (31 ± 2 %) for the linear particle depolarization ratio at 355 (532) nm, and 0.3 ± 0.2 (0.2 ± 0.2) for the extinction-related Ångström exponent (backscatter-related Ångström exponent) between 355 and 532 nm. This study is the first to report comprehensive optical properties of the Arabian dust particles based on 1-year long observations, using to their fullest the capabilities of a multi-wavelength Raman lidar instrument. The results suggest that the mineral dust properties over the Middle East and western Asia, including the observation site, are comparable to those of African mineral dust with regard to the particle depolarization ratios, but not for lidar ratios. The smaller lidar ratio values in this study compared to the reference studies are attributed to the difference in the geochemical characteristics of the soil originating in the study region compared to northern Africa.

scholarly journals Smoke of extreme Australian bushfires observed in the stratosphere over Punta Arenas, Chile, in January 2020: optical thickness, lidar ratios, and depolarization ratios at 355 and 532 nm

2020 ◽  
Author(s):  
Kevin Ohneiser ◽  
Albert Ansmann ◽  
Holger Baars ◽  
Patric Seifert ◽  
Boris Barja ◽  
...  
Keyword(s):  
Optical Thickness ◽  
Stratospheric Aerosol ◽  
Data Sets ◽  
Depolarization Ratio ◽  
Smoke Particles ◽  
Important Input ◽  
Lidar Ratio ◽  
Linear Depolarization Ratio ◽  
532 Nm ◽  
Depolarization Ratios

Abstract. We present particle optical properties of stratospheric smoke layers observed over Punta Arenas (53.2° S, 70.9° W), Chile, at the southernmost tip of South America in January 2020. The smoke originated from the record-breaking bushfires in Australia. The stratospheric aerosol optical thickness reached values up to 0.7 at 532 nm in mid January 2020. The measured smoke extinction-to-backscatter ratios (lidar ratios) and linear depolarization ratios at 355 and 532 nm wavelength indicate shape, size, and light-absorption properties and are important input parameters in the analysis of spaceborne lidar observations of the CALIPSO and Aeolus missions. They are also of key importance regarding the homogenization of the overall Aeolus (355 nm wavelength) and CALIPSO (532 nm wavelength) smoke data sets and interpretation of the observations with respect to the spread of the smoke particles across the southern hemisphere and decay of the stratospheric perturbation. We found typical values and spectral dependencies of the lidar ratio and linear depolarization ratio for aged stratospheric smoke. At 355 nm, the lidar ratio and depolarization ratio ranged from 53–97 sr and 0.2–0.26, respectively. At 532 nm, the lidar ratios were higher (76–104 sr) and the depolarization ratios were lower with values around 0.15. The found lidar ratio and depolarization ratio values for Australian smoke are in good agreement with respective ones obtained from observations of stratospheric smoke layers over central Europe originating from the record-breaking Canadian wildfires in the summer of 2017. The higher 532 nm lidar ratios, however, indicate stronger absorption by the Australian smoke particles.

scholarly journals Seasonal variability of aerosol optical properties observed by means of a Raman lidar at an EARLINET site over Northeastern Spain

2011 ◽  
Vol 11 (1) ◽  
pp. 175-190 ◽  
Author(s):  
M. Sicard ◽  
F. Rocadenbosch ◽  
M. N. M. Reba ◽  
A. Comerón ◽  
S. Tomás ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Optical Properties ◽  
Planetary Boundary Layer ◽  
Optical Thickness ◽  
Seasonal Variability ◽  
Aerosol Optical Thickness ◽  
Saharan Dust ◽  
Raman Lidar ◽  
Aerosol Optical Properties ◽  
Lidar Ratio

Abstract. The annual and seasonal variability of aerosol optical properties observed by means of a Raman lidar over Northeastern Spain has been assessed. The lidar representativeness has first been checked against sun-photometer measurements in terms of aerosol optical thickness. Then the annual cycle and the seasonal variability of the planetary boundary layer aerosol optical thickness and its fraction compared to the columnar optical thickness, the lidar ratio, the backscatter-related Ångström exponent and the planetary boundary layer height are analyzed and discussed. Winter and summer mean profiles of extinction, backscatter and lidar ratio retrieved with the Raman algorithm are presented. The analysis shows the impact of most of the natural events (Saharan dust intrusions, wildfires, etc.) and meteorological situations (summer anticyclonic situation, the formation of the Iberian thermal low, winter long-range transport from North Europe and/or North America, re-circulation flows, etc.) occurring in the Barcelona area. A detailed study of a special event including a combined intrusion of Saharan dust and biomass-burning particles proves the suitability of combining the retrieval of aerosol optical properties from Raman and pure elastic lidar measurements to discriminate spatially different types of aerosols and to follow their spatial and temporal evolution.

scholarly journals Evaluation of the Lidar/Radiometer Inversion Code (LIRIC) to determine microphysical properties of volcanic and desert dust

2013 ◽  
Vol 6 (7) ◽  
pp. 1707-1724 ◽  
Author(s):  
J. Wagner ◽  
A. Ansmann ◽  
U. Wandinger ◽  
P. Seifert ◽  
A. Schwarz ◽  
...  
Keyword(s):  
Spherical Particle ◽  
Dust Particles ◽  
Depolarization Ratio ◽  
Particle Fraction ◽  
Raman Lidar ◽  
Desert Dust ◽  
Microphysical Properties ◽  
Coarse Mode ◽  
Fine Mode ◽  
Lidar Ratio

Abstract. The Lidar/Radiometer Inversion Code (LIRIC) combines the multiwavelength lidar technique with sun/sky photometry and allows us to retrieve vertical profiles of particle optical and microphysical properties separately for fine-mode and coarse-mode particles. After a brief presentation of the theoretical background, we evaluate the potential of LIRIC to retrieve the optical and microphysical properties of irregularly shaped dust particles. The method is applied to two very different aerosol scenarios: a strong Saharan dust outbreak towards central Europe and an Eyjafjallajökull volcanic dust event. LIRIC profiles of particle mass concentrations for the coarse-mode as well as for the non-spherical particle fraction are compared with results for the non-spherical particle fraction as obtained with the polarization-lidar-based POLIPHON method. Similar comparisons for fine-mode and spherical particle fractions are presented also. Acceptable agreement between the different dust mass concentration profiles is obtained. LIRIC profiles of optical properties such as particle backscatter coefficient, lidar ratio, Ångström exponent, and particle depolarization ratio are compared with direct Raman lidar observations. Systematic deviations between the LIRIC retrieval products and the Raman lidar measurements of the desert dust lidar ratio, depolarization ratio, and spectral dependencies of particle backscatter and lidar ratio point to the applied spheroidal-particle model as main source for these uncertainties in the LIRIC results.

scholarly journals Optical and microphysical characterization of aerosol layers over South Africa by means of multi-wavelength depolarization and Raman lidar measurements

2015 ◽  
Vol 15 (23) ◽  
pp. 35237-35276
Author(s):  
E. Giannakaki ◽  
P. G. van Zyl ◽  
D. Müller ◽  
D. Balis ◽  
M. Komppula
Keyword(s):  
South Africa ◽  
Biomass Burning ◽  
Single Scattering ◽  
Effective Radius ◽  
Depolarization Ratio ◽  
Raman Lidar ◽  
Desert Dust ◽  
Multi Wavelength ◽  
Lidar Ratio ◽  
532 Nm

Abstract. Optical and microphysical properties of different aerosol types over South Africa measured with a multi-wavelength polarization Raman lidar are presented. This study could assist in bridging existing gaps relating to aerosol properties over South Africa, since limited long-term data of this type is available for this region. The observations were performed under the framework of the EUCAARI campaign in Elandsfontein. The multi-wavelength PollyXT Raman lidar system was used to determine vertical profiles of the aerosol optical properties, i.e. extinction and backscatter coefficients, Ångström exponents, lidar ratio and depolarization ratio. The mean microphysical aerosol proper ties, i.e. effective radius and single scattering, albedo were retrieved with an advanced inversion algorithm. Clear differences were observed for the intensive optical properties of atmospheric layers of biomass burning and urban/industrial aerosols. Our results reveal a wide range of optical and microphysical parameters for biomass burning aerosols. This indicates probable mixing of biomass burning aerosols with desert dust particles, as well as the possible continuous influence of urban/industrial aerosol load in the region. The lidar ratio at 355 nm, the linear particle depolarization ratio at 355 nm and the extinction-related Ångström exponent from 355 to 532 nm were 52 ± 7 sr; 0.9 ± 0.4 % and 2.3 ± 0.5, respectively for urban/industrial aerosols, while these values were 92 ± 10 sr; 3.2 ± 1.3 %; 2.0 ± 0.4 respectively for biomass burning aerosols layers. Biomass burning particles are larger and slightly less absorbing compared to urban/industrial aerosols. The particle effective radius were found to be 0.10 ± 0.03, 0.17 ± 0.04 and 0.13 ± 0.03 μm for urban/industrial, biomass burning, and mixed biomass burning and desert dust aerosols, respectively, while the single scattering albedo at 532 nm were 0.87 ± 0.06, 0.90 ± 0.06, and 0.88 ± 0.07 (at 532 nm), respectively for these three types of aerosols. Our results were within the same range of previously reported values.

scholarly journals Optical and geometrical aerosol particle properties over the United Arab Emirates

2020 ◽  
Author(s):  
Maria Filioglou ◽  
Elina Giannakaki ◽  
John Backman ◽  
Jutta Kesti ◽  
Anne Hirsikko ◽  
...  
Keyword(s):  
Aerosol Particle ◽  
United Arab Emirates ◽  
Mineral Dust ◽  
Depolarization Ratio ◽  
Raman Lidar ◽  
Particle Properties ◽  
Measurement Site ◽  
Lidar Ratio ◽  
One Year ◽  
532 Nm

Abstract. One-year of ground-based night-time Raman lidar observations have been analysed under the Optimization of Aerosol Seeding In rain enhancement Strategies (OASIS) project, in order to characterize the aerosol particle properties over a rural site in the United Arab Emirates. In total, 1130 aerosol particle layers were detected during the one-year measurement campaign which took place between March 2018 and February 2019. Several subsequent aerosol layers could be observed simultaneously in the atmosphere up to 11 km. The observations indicate that the measurement site is a receptor of frequent dust events but predominantly the dust is mixed with aerosols of anthropogenic and/or marine origin. The mean aerosol optical depth over the measurement site ranged at 0.37 ± 0.12 and 0.21 ± 0.11 for the 355 and 532 nm, respectively. Moreover, a mean lidar ratio of 43 ± 11 sr at a wavelength of 355 nm and 39 ± 10 sr at 532 nm was found. The average linear particle depolarization ratio measured over the course of the campaign was 15 ± 6 % and 19 ± 7 % at 355 nm and 532 nm wavelengths, respectively. Since the region is both a source and a receptor of mineral dust, we have also explored the properties of Arabian mineral dust of the greater area of United Arab of Emirates and the Arabian Peninsula. The observed Arabian dust particle properties were 45 ± 5 (42 ± 5) sr at 355 (532) nm for the lidar ratio, 25 ± 2 % (31 ± 2 %) for the linear particle depolarization ratio at 355 (532) nm, and 0.3 ± 0.2 (0.2 ± 0.2) for the extinction‑related Ångström exponent (backscatter‑related Ångström exponent) between 355 and 532 nm. This study is the first to report comprehensive optical properties of the Arabian dust particles based on long term observations, using at the fullest the capabilities of a multi wavelength Raman lidar instrument. The results suggest that the mineral dust properties over the Middle East and western Asia, including the observation site, are comparable to those of African mineral dust with regard to the particle depolarization ratios but not for lidar ratios. The smaller lidar ratio values in this study compared to the reference studies are attributed to the difference in the geochemical characteristics of the soil originating in the study region compared to Northern Africa.

scholarly journals Smoke of extreme Australian bushfires observed in the stratosphere over Punta Arenas, Chile, in January 2020: optical thickness, lidar ratios, and depolarization ratios at 355 and 532 nm

2020 ◽  
Vol 20 (13) ◽  
pp. 8003-8015 ◽  
Author(s):  
Kevin Ohneiser ◽  
Albert Ansmann ◽  
Holger Baars ◽  
Patric Seifert ◽  
Boris Barja ◽  
...  
Keyword(s):  
Optical Thickness ◽  
Stratospheric Aerosol ◽  
Data Sets ◽  
Depolarization Ratio ◽  
Important Input ◽  
Lidar Ratio ◽  
Linear Depolarization Ratio ◽  
Aerosol Parameters ◽  
532 Nm ◽  
Depolarization Ratios

Abstract. We present particle optical properties of stratospheric smoke layers observed with multiwavelength polarization Raman lidar over Punta Arenas (53.2∘ S, 70.9∘ W), Chile, at the southernmost tip of South America in January 2020. The smoke originated from the record-breaking bushfires in Australia. The stratospheric aerosol optical thickness reached values up to 0.85 at 532 nm in mid-January 2020. The main goal of this rapid communication letter is to provide first stratospheric measurements of smoke extinction-to-backscatter ratios (lidar ratios) and particle linear depolarization ratios at 355 and 532 nm wavelengths. These aerosol parameters are important input parameters in the analysis of spaceborne CALIPSO and Aeolus lidar observations of the Australian smoke spreading over large parts of the Southern Hemisphere in January and February 2020 up to heights of around 30 km. Lidar and depolarization ratios, simultaneously measured at 355 and 532 nm, are of key importance regarding the homogenization of the overall Aeolus (355 nm wavelength) and CALIPSO (532 nm wavelength) lidar data sets documenting the spread of the smoke and the decay of the stratospheric perturbation, which will be observable over the entire year of 2020. We found typical values and spectral dependencies of the lidar ratio and linear depolarization ratio for aged stratospheric smoke. At 355 nm, the lidar ratio and depolarization ratio ranged from 53 to 97 sr (mean 71 sr) and 0.2 to 0.26 (mean 0.23), respectively. At 532 nm, the lidar ratios were higher (75–112 sr, mean 97 sr) and the depolarization ratios were lower with values of 0.14–0.22 (mean 0.18). The determined depolarization ratios for aged Australian smoke are in very good agreement with respective ones for aged Canadian smoke, observed with lidar in stratospheric smoke layers over central Europe in the summer of 2017. The much higher 532 nm lidar ratios, however, indicate stronger absorption by the Australian smoke particles.

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