scholarly journals Aeolus L2A Aerosol Optical Properties Product: Standard Correct Algorithm and Mie Correct Algorithm

2021 ◽  
Author(s):  
Thomas Flament ◽  
Dimitri Trapon ◽  
Adrien Lacour ◽  
Alain Dabas ◽  
Frithjof Ehlers ◽  
...  
Keyword(s):  
Optical Properties ◽  
Dust Emission ◽  
Thermal Conditions ◽  
Calibration Method ◽  
Saharan Dust ◽  
High Spectral Resolution ◽  
Correct Algorithm ◽  
Lidar Ratio ◽  
Product Standard ◽  
High Spectral Resolution Lidar

Abstract. Aeolus carries ALADIN, the first High Spectral Resolution Lidar (HSRL) in space. Although ALADIN was optimized to measure winds, its two measurement channels can also be used to derive optical properties of atmospheric particles, including a direct retrieval of the lidar ratio. This paper presents the two main algorithms of the optical properties product called Level 2A product, as they are implemented in version 3.12 of the processor, corresponding to the data labelled Baseline 12. The theoretical basis is the same as in Flamant et al. (2008). Here, we also show the in orbit performance of these algorithms. We also explain the adaptation of the calibration method, which is needed to cope with unforeseen variations of the instrument radiometric performance due to the in-orbit strain of the primary mirror under varying thermal conditions. Then we discuss the limitations of the algorithms and future improvements. We demonstrate that the L2A product provides valuable information about airborne particles, in particular we demonstrate the capacity to retrieve a useful lidar ratio from Aeolus observations. This is illustrated on a case of Saharan dust emission, observed in June 2020.

scholarly journals Aeolus L2A aerosol optical properties product: standard correct algorithm and Mie correct algorithm

2021 ◽  
Vol 14 (12) ◽  
pp. 7851-7871 ◽  
Author(s):  
Thomas Flament ◽  
Dimitri Trapon ◽  
Adrien Lacour ◽  
Alain Dabas ◽  
Frithjof Ehlers ◽  
...  
Keyword(s):  
Optical Properties ◽  
Thermal Conditions ◽  
Calibration Method ◽  
Saharan Dust ◽  
High Spectral Resolution ◽  
Correct Algorithm ◽  
Lidar Ratio ◽  
Measurement Channels ◽  
Product Standard ◽  
High Spectral Resolution Lidar

Abstract. Aeolus carries the Atmospheric LAser Doppler INstrument (ALADIN), the first high-spectral-resolution lidar (HSRL) in space. Although ALADIN is optimized to measure winds, its two measurement channels can also be used to derive optical properties of atmospheric particles, including a direct retrieval of the lidar ratio. This paper presents the standard correct algorithm and the Mie correct algorithm, the two main algorithms of the optical properties product called the Level-2A product, as they are implemented in version 3.12 of the processor, corresponding to the data labelled Baseline 12. The theoretical basis is the same as in Flamant et al. (2008). Here, we also show the in-orbit performance of these algorithms. We also explain the adaptation of the calibration method, which is needed to cope with unforeseen variations of the instrument radiometric performance due to the in-orbit strain of the primary mirror under varying thermal conditions. Then we discuss the limitations of the algorithms and future improvements. We demonstrate that the L2A product provides valuable information about airborne particles; in particular, we demonstrate the capacity to retrieve a useful lidar ratio from Aeolus observations. This is illustrated using Saharan dust aerosol observed in June 2020.

scholarly journals Saharan Dust Events Over the Northern Mediterranean: 4 Years of Measurements Over 4 Earlinet Stations

2020 ◽  
Vol 237 ◽  
pp. 05010
Author(s):  
Ourania Soupiona ◽  
Alex Papayannis ◽  
Maria Mylonaki ◽  
Nikolaos Papagiannopoulos ◽  
Pablo Ortiz-Amezcua ◽  
...  
Keyword(s):  
Saharan Dust ◽  
High Spectral Resolution ◽  
Visible Range ◽  
Geometrical Properties ◽  
Lidar Ratio ◽  
Linear Depolarization Ratio ◽  
Dust Events ◽  
High Spectral Resolution Lidar ◽  
Different Sources ◽  
532 Nm

Four years (2014-2017) of observations of depolarization Raman Lidar systems of four EARLINET (European Aerosol research Lidar Network) stations [from West to East: Granada (Spain), Potenza (Italy), Athens (Greece) and Limassol (Cyprus)] were collected and used to a statistical analysis of Saharan dust events over Mediterranean basin. In this study, emphasis is given to the consistency of the particle linear depolarization ratio (δp532), the extinction-to-backscatter ratio mentioned as Lidar Ratio (LR532) and the Aerosol Optical Thickness (AOT532) within the observed Saharan dust layers, corresponding to the visible range (532 nm). Geometrical properties and clusters of aerosol mixtures are also presented. Our clustering was based on previous classification by airborne High Spectral Resolution Lidar (HSRL) observations and was further supported by backward trajectory analysis. We found mean δp532 values of 0.24±0.05, 0.26±0.06, 0.28±0.05 and 0.28±0.04, mean LR532 values of 52±8 sr, 51±9 sr, 52±9 sr and 49±6 sr, mean AOT532 values of 0.40±0.31, 0.11±0.07, 0.12±0.10 and 0.32±0.17 and mean layer thicknesses of 3392±1458 m, 2150±1082 m, 1872±816 m and 1716±567 m for Granada, Potenza, Athens and Limassol respectively. This work could assist in bridging the existing gaps related to the extensive and intensive dust aerosol properties over the Mediterranean and enriching the bibliography about mixed aerosol layers from different sources (e.g. dust and biomass burning (BB) aerosols, dust and urban/ industrial aerosols).

scholarly journals Dual-Wavelength High-Spectral-Resolution Lidar for Profiling Optical Properties of Aerosol and Cloud

2020 ◽  
Vol 237 ◽  
pp. 02012
Author(s):  
Xue Shen ◽  
Nanchao Wang ◽  
Dong Liu ◽  
Da Xiao ◽  
Yuhang Rong ◽  
...  
Keyword(s):  
Optical Properties ◽  
Spectral Resolution ◽  
Michelson Interferometer ◽  
Calibration Method ◽  
Dual Wavelength ◽  
High Spectral Resolution ◽  
Internal Calibration ◽  
Multiple Observations ◽  
High Spectral Resolution Lidar ◽  
Absorption Filter

A dual-wavelength high-spectral-resolution lidar (HSRL) based on an iodine absorption filter and a field-widened Michelson interferometer (FWMI) has been developed to profile backscatter and extinction coefficients of aerosols and clouds accurately. This instrument was tested and calibrated on multiple observations in Hangzhou and Zhoushan, respectively, from August 2018 to April 2019. This paper discusses the design and the internal calibration method of the lidar system in detail, with several typical cases of observations and the analysis of these data products. The optical properties of urban aerosols in Hangzhou and the evolvement of clouds in Zhoushan are presented, respectively.

scholarly journals Spatial distribution and optical properties of Saharan dust observed by airborne high spectral resolution lidar during SAMUM 2006

Tellus B ◽  
2009 ◽  
Vol 61 (1) ◽  
pp. 131-143 ◽  
Author(s):  
Michael Esselborn ◽  
Martin Wirth ◽  
Andreas Fix ◽  
Bernadett Weinzierl ◽  
Katharina Rasp ◽  
...  
Keyword(s):  
Optical Properties ◽  
Spatial Distribution ◽  
Spectral Resolution ◽  
Saharan Dust ◽  
High Spectral Resolution ◽  
High Spectral Resolution Lidar

scholarly journals Retrieval of Aerosol Optical Properties Based on High Spectral Resolution Lidar

2020 ◽  
Vol 237 ◽  
pp. 08018
Author(s):  
Da Xiao ◽  
Tianfen Zhong ◽  
Xue Shen ◽  
Nanchao Wang ◽  
Yuhang Rong ◽  
...  
Keyword(s):  
Optical Properties ◽  
Spectral Resolution ◽  
High Spectral Resolution ◽  
Urban Aerosol ◽  
Aerosol Optical Properties ◽  
Climate Research ◽  
Atmospheric Remote Sensing ◽  
Retrieval Algorithms ◽  
Lidar Ratio ◽  
High Spectral Resolution Lidar

The detection of clouds and aerosols is important for climate research. Lidar has been widely used in atmospheric remote sensing research because of its high spatial and temporal resolution and ability to detect profiles. High spectral resolution lidar (HSRL) accurately calculates the optical properties of aerosols and clouds without relying on any assumptions. Based on the 532nm iodine HSRL system, the lidar ratio of the urban aerosol in Hangzhou is 40-50sr, and the average lidar ratio of the cirrus is 24.79sr, demonstrating that the HSRL system and retrieval algorithms accurately obtain the optical properties of clouds and aerosols.

Spatial distribution and optical properties of Saharan dust observed by airborne high spectral resolution lidar during SAMUM 2006

Tellus B ◽  
2009 ◽  
Vol 61 (1) ◽  
Author(s):  
Michael Esselborn ◽  
Martin Wirth ◽  
Andreas Fix ◽  
Bernadett Weinzierl ◽  
Katharina Rasp ◽  
...  
Keyword(s):  
Optical Properties ◽  
Spatial Distribution ◽  
Spectral Resolution ◽  
Saharan Dust ◽  
High Spectral Resolution ◽  
High Spectral Resolution Lidar

scholarly journals Aerosol classification from airborne HSRL and comparisons with the CALIPSO vertical feature mask

2013 ◽  
Vol 6 (1) ◽  
pp. 1815-1858 ◽  
Author(s):  
S. P. Burton ◽  
R. A. Ferrare ◽  
M. A. Vaughan ◽  
A. H. Omar ◽  
R. R. Rogers ◽  
...  
Keyword(s):  
High Spectral Resolution ◽  
Dependent Observations ◽  
Aerosol Retrieval ◽  
Direct Measurements ◽  
Aerosol Classification ◽  
Lidar Ratio ◽  
Langley Research Center ◽  
High Spectral Resolution Lidar ◽  
Aerosol Types ◽  
Aerosol Type

Abstract. Aerosol classification products from the NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL-1) on the NASA B200 aircraft are compared with coincident V3.01 aerosol classification products from the CALIOP instrument on the CALIPSO satellite. For CALIOP, aerosol classification is a key input to the aerosol retrieval, and must be inferred using aerosol loading-dependent observations and location information. In contrast, HSRL-1 makes direct measurements of aerosol intensive properties, including the lidar ratio, that provide information on aerosol type. In this study, comparisons are made for 109 underflights of the CALIOP orbit track. We find that 62% of the CALIOP marine layers and 54% of the polluted continental layers agree with HSRL-1 classification results. In addition, 80% of the CALIOP desert dust layers are classified as either dust or dusty mix by HSRL-1. However, agreement is less for CALIOP smoke (13%) and polluted dust (35%) layers. Specific case studies are examined, giving insight into the performance of the CALIOP aerosol type algorithm. In particular, we find that the CALIOP polluted dust type is overused due to an attenuation-related depolarization bias. Furthermore, the polluted dust type frequently includes mixtures of dust plus marine aerosol. Finally, we find that CALIOP's identification of internal boundaries between different aerosol types in contact with each other frequently do not reflect the actual transitions between aerosol types accurately. Based on these findings, we give recommendations which may help to improve the CALIOP aerosol type algorithms.

scholarly journals Observations of the spectral dependence of linear particle depolarization ratio of aerosols using NASA Langley airborne High Spectral Resolution Lidar

2015 ◽  
Vol 15 (23) ◽  
pp. 13453-13473 ◽  
Author(s):  
S. P. Burton ◽  
J. W. Hair ◽  
M. Kahnert ◽  
R. A. Ferrare ◽  
C. A. Hostetler ◽  
...  
Keyword(s):  
Case Studies ◽  
Spectral Resolution ◽  
Spectral Dependence ◽  
Saharan Dust ◽  
Spherical Particles ◽  
High Spectral Resolution ◽  
Depolarization Ratio ◽  
Dust Layer ◽  
High Spectral Resolution Lidar ◽  
532 Nm

Abstract. Linear particle depolarization ratio is presented for three case studies from the NASA Langley airborne High Spectral Resolution Lidar-2 HSRL-2). Particle depolarization ratio from lidar is an indicator of non-spherical particles and is sensitive to the fraction of non-spherical particles and their size. The HSRL-2 instrument measures depolarization at three wavelengths: 355, 532, and 1064 nm. The three measurement cases presented here include two cases of dust-dominated aerosol and one case of smoke aerosol. These cases have partial analogs in earlier HSRL-1 depolarization measurements at 532 and 1064 nm and in literature, but the availability of three wavelengths gives additional insight into different scenarios for non-spherical particles in the atmosphere. A case of transported Saharan dust has a spectral dependence with a peak of 0.30 at 532 nm with smaller particle depolarization ratios of 0.27 and 0.25 at 1064 and 355 nm, respectively. A case of aerosol containing locally generated wind-blown North American dust has a maximum of 0.38 at 1064 nm, decreasing to 0.37 and 0.24 at 532 and 355 nm, respectively. The cause of the maximum at 1064 nm is inferred to be very large particles that have not settled out of the dust layer. The smoke layer has the opposite spectral dependence, with the peak of 0.24 at 355 nm, decreasing to 0.09 and 0.02 at 532 and 1064 nm, respectively. The depolarization in the smoke case may be explained by the presence of coated soot aggregates. We note that in these specific case studies, the linear particle depolarization ratio for smoke and dust-dominated aerosol are more similar at 355 nm than at 532 nm, having possible implications for using the particle depolarization ratio at a single wavelength for aerosol typing.

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