Assessment of Aerosol Extinction to Backscatter Ratio Measurements Made at 694.3 nm in Tucson, Arizona

Reagan, John A.; Apte, M. V.; Ben‐David, Avishai; Herman, Benjamin M.

doi:10.1080/02786828808959184

Cited by 23 publications

(5 citation statements)

References 13 publications

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“…The air molecule ratio S m has a constant value of 8Π/3, whereas the aerosol lidar ratio (S a ) always varies, depending on the aerosol size distribution and particle refractive index and so on [ Reagan et al , 1988; Franke et al , 2001].…”

Section: Retrieval Methodsmentioning

confidence: 99%

Dust aerosol vertical structure measurements using three MPL lidars during 2008 China‐U.S. joint dust field experiment

Huang

et al. 2010

J. Geophys. Res.

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[1] The 2008 China-U.S. joint dust field experiment, which aims to estimate the effect of dust on radiative forcing and its associated climatic impacts, was conducted during the dust-intensive period from March to June of 2008 over the Loess Plateau of northwest China. Dust aerosol vertical profiles and long-range transport of dust storm were measured with the three MPL-net Micro-Pulse Lidar (MPL) systems as well as other ground-based instruments and spaceborne remote sensing techniques. In this study, to ensure the effectiveness of the retrieval results, an effective algorithm was introduced for retrieving aerosol optical properties and vertical profiles from Mie lidar measurements. The advantage of this algorithm is that Aerosol Optical Depth (AOD) retrieval from lidar measurements can be accomplished without the use of the so-called lidar ratio for the corresponding quantities obtained from the AERONET Sun photometer. Dust aerosol vertical profiles are derived successfully from three MPL lidar systems using this algorithm. A dust storm that affected a large part of northwest China on 2 May 2008 was studied using measurements obtained from the three ground-based lidar systems, satellite-borne instruments and NCEP reanalysis data. The results show that different aerosol vertical structures were present at each site, and the colder Siberia air mass and stronger and longer cyclones around Mongolia are key features leading to the dust storm.

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Section: Retrieval Methodsmentioning

confidence: 99%

Dust aerosol vertical structure measurements using three MPL lidars during 2008 China‐U.S. joint dust field experiment

Huang

et al. 2010

J. Geophys. Res.

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“…There might be two reasons for this phenomenon. One is that dust aerosols on the surface are lifted into the biomass burning plume (Müller et al, 2007) and the other is the nonsphericity of particles due to the coagulation of smoke particles during the aging process (Reid et al, 1998). Therefore, the LR in the range of 100-120 sr may correspond to large δ because of aged forest fire aerosols.…”

Section: Reasons For Lr Variation With Heightmentioning

confidence: 99%

Long-term variation in aerosol lidar ratio in Shanghai based on Raman lidar measurements

Liu

Chen

et al. 2021

Atmos. Chem. Phys.

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Abstract. Accurate lidar ratio (LR) and better understanding of its variation characteristics can not only improve the retrieval accuracy of parameters from elastic lidar, but also play an important role in assessing the impacts of aerosols on climate. Using the observational data of a Raman lidar in Shanghai from 2017 to 2019, LRs at 355 nm were retrieved and their variations and influence factors were analyzed. Within the height range of 0.5–5 km, about 90 % of the LRs were distributed in 10–80 sr with an average value of 41.0 ± 22.5 sr, and the LR decreased with the increase in height. The volume depolarization ratio (δ) was positively correlated with LR, and it also decreased with the increase in height, indicating that the vertical distribution of particle shape was one of the influence factors of the variations in LR with height. LR had a strong dependence on the original source of air masses. Affected by the aerosols transported from the northwest, the average LR was the largest, 44.2 ± 24.7 sr, accompanied by the most irregular particle shape. The vertical distribution of LR was affected by atmospheric turbidity, with the greater gradient of LR under clean conditions. The LR above 1 km could be more than 80 sr, when Shanghai was affected by biomass burning aerosols.

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“…The parameters were constructed on the basis of a semiempirical theory for irregular particles [Pollack and Cuzzi, 1980]. Slant-path lidar observations in the arid southwest of the United States yielded lidar ratios between 10 and 45 sr at 694 nm [Reagan et al, 1988]. Herein, values in the range between 10 and 20 sr were attributed to soil-type, almost nonabsorbing particles in the coarse mode.…”

Section: Comparison Of Lidar Ratiomentioning

confidence: 99%

Saharan dust over a central European EARLINET‐AERONET site: Combined observations with Raman lidar and Sun photometer

et al. 2003

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Combined observations with an advanced aerosol water‐vapor temperature Raman lidar and a Sun photometer are used for a detailed characterization of geometrical and optical properties of a continental‐scale Saharan dust event observed over Leipzig (51.3°N, 12.4°E), Germany, from 13 to 15 October 2001. The Raman lidar is part of the European Aerosol Research Lidar Network (EARLINET). Automatic observations of aerosol optical depth and sky brightness are made with the Sun photometer in the framework of the worldwide operating Aerosol Robotic Network (AERONET). The dust plume reached a top height of 6000 m. Sun photometer and lidar observations showed a constant increase of columnar optical depth at 532 nm from 0.25 on 13 October 2001 to a maximum of ∼0.63 on 14 October 2001. According to observations with lidar, up to 90% of the optical depth at the wavelength of 532 nm was contributed by the dust layer above 1000‐m height. Ångström exponents from Sun photometer observations between 380 and 1020 nm were ∼0.45 at the beginning of the dust period, and dropped to minimum values of 0.14 during the peak of the dust outbreak. Vertically resolved Ångström exponents derived from lidar profiles of the extinction coefficients at 355 and 532 nm showed a strong variability with values as low as −0.2 in the center of the dust plume. Below 1000‐m height column‐averaged Ångström exponents strongly varied between 1.0 in the beginning of the dust period and 0.39 on 14 October 2001 when the dust penetrated into the boundary layer. Comparison of column‐averaged optical depth and Ångström exponents derived from lidar and Sun photometer observations showed excellent agreement. Particle depolarization ratios of up to 25% were derived from lidar observations at 532 nm. Scattering phase functions retrieved from Sun photometer observations indicated particles of nonspherical shape. This shape caused unusually large particle extinction‐to‐backscatter (lidar) ratios at 532 nm in the range from 50 to 80 sr. There were substantial deviations of the lidar ratio at 532 nm derived from both measurement methods. They are explained by the effect of particle shape.

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Assessment of Aerosol Extinction to Backscatter Ratio Measurements Made at 694.3 nm in Tucson, Arizona

Cited by 23 publications

References 13 publications

Dust aerosol vertical structure measurements using three MPL lidars during 2008 China‐U.S. joint dust field experiment

Dust aerosol vertical structure measurements using three MPL lidars during 2008 China‐U.S. joint dust field experiment

Long-term variation in aerosol lidar ratio in Shanghai based on Raman lidar measurements

Saharan dust over a central European EARLINET‐AERONET site: Combined observations with Raman lidar and Sun photometer

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