Real Time Derivation of Atmospheric Aerosol Optical Properties by Concurrent Measurements of Optical and Sampling Instruments

Aminuddin, Jamrud; Okude, S.; Lagrosas, Nofel; Manago, Naohiro; Kuze, Hiroaki

doi:10.4236/ojap.2018.72008

Cited by 7 publications

(9 citation statements)

References 33 publications

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“…In this study, the 6S radiative transfer model (Second Simulation of the Satellite Signal in the Solar Spectrum), which is based on the estimation of aerosol models for the boundary layer and the atmosphere radiation transmission process during the Sun-Ground-Sensor, was selected [46]. It is used with a spectral resolution of 2.5 nm, which can greatly improve the calculation accuracy of scattered aerosols and molecules, and radiation absorption characteristics [47]. The advantage of using the 6S model is its ability to estimate direct and diffuse components using a limited number of inputs for any spectral band within the entire solar domain [48].…”

Section: Radiative Transfer Handled By 6smentioning

confidence: 99%

Retrieval of Aerosol Optical Thickness with Custom Aerosol Model Using SKYNET Data over the Chiba Area

2021

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The retrieval of the aerosol optical thickness (AOT) from remotely-sensed data relies on the adopted aerosol model. However, the method of this technique has been rather limited because of the high variability of the surface albedo, in addition to the spatial variability in the aerosol properties over the land surfaces. To overcome unsolved problems, we proposed a method for the visibility-derived AOT estimation from SKYNET-based measurement and daytime satellite images with a custom aerosol model over the Chiba area (35.62° N, 140.10° E), which is located in the greater Tokyo metropolitan area in Japan. Different from conventionally-used aerosol models for the boundary layer, we created a custom aerosol model by using sky-radiometer observation data of aerosol volume size distribution and refractive indices, coupled with spectral response functions (SPFs) of satellite visible bands to alleviate the wide range of path-scattered radiance. We utilized the radiative transfer code 6S to implement the radiative transfer calculation based on the created custom aerosol model. The concurrent data from ground-based measurement are used in the radiative analysis, namely the temporal variation of AOT from SKYNET. The radiative estimation conducted under clear-sky conditions with minimum aerosol loading is used for the determination of the surface albedo, so that the 6S simulation yields a well-defined relation between total radiance and surface albedo. We made look-up tables (LUTs) pixel-by-pixel over the Chiba area for the custom aerosol model to retrieve the satellite AOT distribution based on the surface albedo. Therefore, such a reference of surface albedo generated from clear-sky conditions, in turn, can be employed to retrieve the spatial distribution of AOT on both clear and relatively turbid days. The value for the AOTs retrieved using the custom aerosol model is found to be stable than conventionally-used typical aerosol models, indicating that our method yields substantially better performance.

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Section: Radiative Transfer Handled By 6smentioning

confidence: 99%

Retrieval of Aerosol Optical Thickness with Custom Aerosol Model Using SKYNET Data over the Chiba Area

2021

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“…An aethalometer (Magee, AE31) measures the values of black carbon (BC) concentration at the seven wavelengths (370, 470, 520, 590, 660, 880, and 950 nm). Then, the temporal change of AEC at the lidar wavelength (532 nm) is calculated by carrying out the interpolation based on the Angstrom exponent [6]. The value of lidar ratio can be estimated by means of the Mie-scattering calculation using aerosol parameters of the mode radius, variance, and the real and imaginary parts of refractive index.…”

Section: Sampling Instruments and Mie-scattering Calculationmentioning

confidence: 99%

“…The mode radius and variance can be directly obtained from the record of a particle counter (Rion, KC22B). The values of refractive index are estimated from the condition that the observed wavelength dependence of both AEC and absorption coefficient is reproduced [6], [7].…”

Section: Sampling Instruments and Mie-scattering Calculationmentioning

confidence: 99%

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Continuous Lidar Observation of Near Surface Aerosol Using Optical and Sampling Data from Ground-Based Instruments

et al. 2020

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Monitoring of near-surface aerosol is important for both public health issues and radiation budget studies. In this study, we report a continuous observation method of aerosol particles by means of a vertical Mie-scattering lidar in combination with other optical and sampling instruments operated at the ground level. In the Fernald method used for processing the lidar signal, the most appropriate value of lidar ratio at 532 nm is estimated from the Mie-scattering calculation. The input parameters, namely, the mode radius, variance, and both real and imaginary parts of refractive index, are so determined as to reproduce the data from ground-based sampling instruments. Instead of the far-end boundary condition, the extinction coefficient at the surface level is used for constraining the retrieved aerosol extinction profile. The correction of the truncation and relative humidity (RH) effects on the scattering data from the sampling is made with the help of the optical data from a visibility-meter. We discuss the observed features in both low and high RH cases. Such a capability will be useful for uninterrupted lidar observations of near-surface aerosols irrespective of the presence of clouds that often hinders signal observations at higher altitudes where the aerosol-free atmosphere is assumed for the conventional Fernald analysis.

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“…Studies of ambient particles with much more complex composition have usually relied on integrated nephelometers [31][32][33][34], wherein the flow rate, temperature and RH inside the instrument are controlled. However, ambiguities are unavoidable for correcting the underestimation of the aerosol scattering coefficient for factors such as the limited angular range (e.g., 7-170 • ) of the scattering measurement, the loss of relatively large particles due to the aerodynamic transport from the inlet pipe to the sample chamber, and the RH difference between ambient and instrumental [31,35,36]. More recently, lidars have been used to investigate the aerosol hygroscopicity, though the studies focused on higher altitudes (>500 m) [37][38][39][40].…”

Section: Introductionmentioning

confidence: 99%

Surface Aerosol Properties Studied Using a Near-Horizontal Lidar

et al. 2019

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Studying near-surface aerosol properties is of importance for a better assessment of the aerosol effect on radiative forcing. We employ the data from a near-horizontal lidar to investigate the diurnal behavior of aerosol extinction and single scattering albedo (SSA) at 349 nm. The response of these parameters to ambient relative humidity (RH) is examined for the data from a one-month campaign conducted in Chiba, Japan, during November 2017, a transition period from fall to winter. The Klett method and adaptive slope method are used in deriving the aerosol extinction coefficient from the lidar data, while the SSA values are retrieved using an aethalometer. Also, a visibility-meter is used to examine the aerosol loading inside the atmospheric boundary layer. It is found that the aerosol growth during the deliquescence phase is more readily observed than the contraction in the efflorescence phase. The decrease of SSA before the deliquescence RH is found for approximately 46% of the deliquescence cases, presumably representing the particle shrinkage of soot particles.

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Real Time Derivation of Atmospheric Aerosol Optical Properties by Concurrent Measurements of Optical and Sampling Instruments

Cited by 7 publications

References 33 publications

Retrieval of Aerosol Optical Thickness with Custom Aerosol Model Using SKYNET Data over the Chiba Area

Retrieval of Aerosol Optical Thickness with Custom Aerosol Model Using SKYNET Data over the Chiba Area

Continuous Lidar Observation of Near Surface Aerosol Using Optical and Sampling Data from Ground-Based Instruments

Surface Aerosol Properties Studied Using a Near-Horizontal Lidar

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