Optical and Microphysical Properties of Upper Clouds Measured with the Raman Lidar and Hydrometeor Videosonde: A Case Study on 29 March 2004 over Tsukuba, Japan

2006 ◽  
Vol 63 (8) ◽  
pp. 2156-2166 ◽  
Author(s):  
Tetsu Sakai ◽  
Narihiro Orikasa ◽  
Tomohiro Nagai ◽  
Masataka Murakami ◽  
Kenichi Kusunoki ◽  
...  
Keyword(s):  
Extinction Coefficient ◽  
Theoretical Calculations ◽  
Ice Crystals ◽  
Lidar Measurement ◽  
Depolarization Ratio ◽  
Raman Lidar ◽  
Microphysical Properties ◽  
Vertical Distributions ◽  
Lidar Ratio ◽  
Cloud Particles

Abstract Optical and microphysical properties of the upper clouds at an altitude range of 5–11 km were measured over Tsukuba, Japan, on 29–30 March 2004 using a ground-based Raman lidar and a balloon-borne hydrometeor videosonde (HYVIS). The Raman lidar measured the vertical distributions of the particle extinction coefficient, backscattering coefficients, depolarization ratio, and extinction-to-backscatter ratio (lidar ratio) at 532 nm; further, it measured the water vapor mixing ratio. The HYVIS measured the vertical distributions of the particle size, shape, cross-sectional area, and number concentration of the cloud particles by taking microscopic images. The HYVIS measurement showed that the cloud particles were ice crystals whose shapes were columnar, bulletlike, platelike, and irregular, and 7–400 μm in size. The Raman lidar measurement showed that the depolarization ratio ranged from 0% to 35% and the lidar ranged from 0.3 to 30 sr for the clouds in ice-saturated air. The comparison between the measured data and theoretical calculations of the cloud optical properties suggests that the observed variations in the depolarization ratio and lidar ratio were primarily due to the variation in the proportion of the horizontally oriented ice crystals in the clouds. The optical thickness of the cloud obtained from the lidar was about 2 times lower than that calculated from the HYVIS data, and the maximum extinction coefficient was about 5 times lower than the HYVIS data. The most probable reason for the differences is the horizontal inhomogeneities of the cloud properties between the measurements sites for the two instruments.

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 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 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 On retrieval of lidar extinction profiles using Two-Stream and Raman techniques

2009 ◽  
Vol 9 (5) ◽  
pp. 20229-20257 ◽  
Author(s):  
I. S. Stachlewska ◽  
C. Ritter
Keyword(s):  
Extinction Coefficient ◽  
Experimental Approach ◽  
The Arctic ◽  
Raman Lidar ◽  
Evaluation Tools ◽  
Simultaneous Measurements ◽  
Arctic Conditions ◽  
Lidar Ratio

Abstract. The Two-Stream technique employes simultaneous measurements performed by two elastic backscatter lidars aiming at each other to sample into the same atmosphere. It allows for a direct retrieval of the extinction coefficient profile from the ratio of the two involved lidar signals. During a few Alfred-Wegener-Institute's (AWI) campaigns dedicated to the Arctic research, the AWI's Polar 2 aircraft with the integrated onboard nadir-aiming Airborne Mobile Merosol Lidar (AMALi) overflew a vicinity of Ny Ålesund on Svalbard, where the zenith-aiming Koldewey Aerosol Raman Lidar (KARL) has been located. This experimental approach gave a unique opportunity to retrieve the extinction profiles with rather rarely used Two-Stream technique against the well established Raman technique. Both methods were applied to data obtained for a clean Arctic conditions during the Arctic Study of Tropospheric clouds and Radiation (ASTAR 2004) campaign and a slightly polluted Arctic conditions during the Svalbard Experiment (SvalEx 2005) campaign. Successful intercomparison of both evaluation tools in a different measurement conditions demonstrates sensitivity and feasibility of the Two-Stream method to obtain particle extinction and backscatter coefficients profiles without assumption of their relationship (lidar ratio). The method has a potential to serve as an extinction retrieval tool for KARL or AMALi simultaneous observations with the spaceborne CALYPSO lidar taken during the ASTAR 2007.

scholarly journals Studies on Aerosol Optical Properties at High Altitude Station in Western Himalayas Using Raman Lidar

2020 ◽  
Vol 237 ◽  
pp. 02034
Author(s):  
Shishir Kumar Singh ◽  
Jaswant ◽  
S.R. Radhakrishnan ◽  
Davender Sethi ◽  
Chhemendra Sharma
Keyword(s):  
Optical Properties ◽  
Extinction Coefficient ◽  
Spherical Particles ◽  
Western Himalayas ◽  
Depolarization Ratio ◽  
Raman Lidar ◽  
Inversion Algorithm ◽  
Backscatter Coefficient ◽  
Aerosol Optical Properties ◽  
Linear Depolarization Ratio

The aerosol optical properties have been investigated using the Raman lidar system for the month of November 2018 at the western Himalayan station of Palampur. Before deriving the optical properties, the lidar data has been applied with initial pre-processing such as Dead time correction, atmospheric noise correction, temporal and spatial averaging, range correction, gluing etc. The optical properties such as backscatter coefficient, extinction coefficient and linear depolarization ratio have been derived by using the inversion algorithm proposed by Fernald. The results show that the backscatter coefficient was found in the range from 9.00E-9 m−1sr−1 to 4.97E-6 m−1sr−1 and the extinction coefficient was found in the range from 3.16E-7m-1 to 1.74E-4m-1. The Linear depolarization ratio was in the range from 0.0179 to 0.621 with lower values at near heights suggesting the dominance of spherical particles at the lower heights. We have also observed a cloud layer at a height of 9.5 km to 12.1 km with high depolarization ratio during the observation period on 22/11/2018.

scholarly journals Single ice crystal measurements during nucleation experiments with the depolarization detector IODE

2010 ◽  
Vol 10 (2) ◽  
pp. 313-325 ◽  
Author(s):  
M. Nicolet ◽  
O. Stetzer ◽  
F. Lüönd ◽  
O. Möhler ◽  
U. Lohmann
Keyword(s):  
Theoretical Calculations ◽  
Scattered Light ◽  
Detection Algorithm ◽  
Ice Nucleation ◽  
Ice Crystals ◽  
Time Signal ◽  
Depolarization Ratio ◽  
Particle Detection ◽  
Mean Values ◽  
High Particle

Abstract. In order to determine the efficiency of different aerosol particles to nucleate ice, an Ice Optical DEpolarization detector (IODE) was developed to distinguish between water droplets and ice crystals in ice nucleation chambers. A laser beam polarized linearly (power: 50 mW, wavelength: 407 nm) is directed through the chamber. The scattered light intensity from particles is measured at a scattering angle of Θ=175° in both polarization components (parallel and perpendicular). The ratio between the perpendicular intensity over the total one yields the depolarization ratio δ. Single particle detection is possible, using a peak detection algorithm. For high particle concentrations, a real-time signal averaging method can also be run simultaneously. The IODE detector was used in connection with the Zurich ice nucleation chamber during the ICIS 2007 workshop where ice nucleation experiments were performed with several aerosol types. In presence of ice crystals, a depolarization ratio could be measured on a particle-by-particle basis. Mean values of δ ranged from 0.24 to 0.37 and agree well with theoretical calculations.

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 1064 nm Raman lidar for extinction and lidar ratio profiling: Cirrus case study

2016 ◽  
Author(s):  
Moritz Haarig ◽  
Ronny Engelmann ◽  
Albert Ansmann ◽  
Igor Veselovskii ◽  
David N. Whiteman ◽  
...  
Keyword(s):  
Extinction Coefficient ◽  
New Technique ◽  
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 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, 532m and 1064 nm.

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.

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