Multiple scattering from clear atmosphere obscured by transparent crystal clouds in satellite-borne lidar sensing

Flesia, Cristina; Starkov, A. V.

doi:10.1364/ao.35.002637

Cited by 8 publications

(8 citation statements)

References 3 publications

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“…10 show the results of our MC simulations reported in terms of the ratios R MSto1 The main properties of our MC simulations in Fig. 10 are in agreement with the results of the work by Flesia and Starkov (1996); the distinctions are due to differences in the phase functions and the configuration characteristics. In ad-dition, the vertical resolution in our work is 7.5 times better, and, therefore, the ratios R MSto1 (d) and R 2to1 (d) are seen in more detail.…”

Section: Two-layered Cloudsupporting

confidence: 81%

“…Values of the input parameters of the chimerical phase functions. It should be noted that the stepwise jump with subsequent decreasing was already reported in the work by Flesia and Starkov (1996), where multiple scattering to a space-borne lidar return from a clear molecular atmosphere obscured by transparent upper-level crystal clouds was assessed by the use of the Monte Carlo technique.…”

Section: Single-layer Cloudsupporting

confidence: 54%

“…On the other hand, results of MC simulations published in the literature (see e.g. Flesia and Starkov, 1996;Donovan, 2016;Reverdy et al, 2015;Szczap et al, 2021) evidenced the following. As it is expected, lidar signals from regions of the cloud-free molecular atmosphere -namely between cloud layers and/or beyond the far edge of a cloud systemare affected by the scattered light emerging from clouds.…”

Section: Introductionmentioning

confidence: 78%

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Multiple-scattering effects on single-wavelength lidar sounding of multi-layered clouds

Shcherbakov,

Szczap,

Mioche

et al. 2024

Atmos. Meas. Tech.

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Abstract. We performed Monte Carlo simulations of single-wavelength lidar signals from multi-layered clouds with special attention focused on the multiple-scattering (MS) effect in regions of the cloud-free molecular atmosphere (i.e. between layers or outside a cloud system). Despite the fact that the strength of lidar signals from the molecular atmosphere is much lower compared to the in-cloud intervals, studies of MS effects in such regions are of interest from scientific and practical points of view. The MS effect on lidar signals always decreases with the increasing distance from the cloud far edge. The decrease is the direct consequence of the fact that the forward peak of particle phase functions is much larger than the receiver field of view (RFOV). Therefore, the photons scattered within the forward peak escape the sampling volume formed by the RFOV (i.e. the escape effect). We demonstrated that the escape effect is an inherent part of MS properties within the free atmosphere beyond the cloud far edge. In the cases of the ground-based lidar, the MS contribution is lower than 5 % within the regions of the cloud-free molecular atmosphere with a distance from the cloud far edge of about 1 km or higher. In the cases of the space-borne lidar, the rate of decrease of the MS contribution is so slow that the threshold of 5 % can hardly be reached. In addition, the effect of non-uniform beam filling is extremely strong. Therefore, practitioners should employ, with proper precautions, lidar data from regions below the cloud base when treating data of a space-borne lidar. In the case of two-layered cloud, the distance of 1 km is sufficiently large so that the scattered photons emerging from the first layer do not affect signals from the second layer when we are dealing with the ground-based lidar. In contrast, signals from the near edge of the second cloud layer are severely affected by the photons emerging from the first layer in the case of a space-borne lidar. We evaluated the Eloranta model (EM) in extreme conditions and showed its good performance in the cases of ground-based and space-borne lidars. At the same time, we revealed the shortcoming that can affect practical applications of the EM. Namely, values of the key parameters – i.e. the ratios of phase functions in the backscatter direction for the nth-order-scattered photon and a singly scattered photon – depend not only on the particle phase function but also on the distance from a lidar to the cloud and the receiver field of view. Those ratios vary within a quite large range, and the MS contribution to lidar signals can be largely overestimated or underestimated if erroneous values of the ratios are assigned to the EM.

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Section: Two-layered Cloudsupporting

confidence: 81%

Section: Single-layer Cloudsupporting

confidence: 54%

Section: Introductionmentioning

confidence: 78%

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Multiple-scattering effects on single-wavelength lidar sounding of multi-layered clouds

Shcherbakov,

Szczap,

Mioche

et al. 2024

Atmos. Meas. Tech.

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“…High anisotropy of scattering of light by large nonspherical ice crystals is the basis of an interesting optical effect: the radiat ion scattered by the crystal particles within a narrow cone around the forward direction is predominant and is greater than the corresponding values for scattering on water droplets and on atmospheric mo lecules. This optical property allo ws the main part of the photons scattered by the crystal particles to remain within the receiver FOV 22 . Nevertheless, it should be noted that even in an optically thin cirrus cloud (τ cl = 0.5), the fraction of doubly scattered photons is about 10 percent.…”

Section: Modeling Results: Effects Of Multiple Scatteringmentioning

confidence: 99%

Modeling of laser pulse propagation in clouds taking into account multiple scattering

Russkova

Kan

2022

28th International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics

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The work proposes an original algorithm of the Monte Carlo method for simulating the propagation of laser pulses in a cloudy atmosphere taking into account all scattering orders. The results of studying the features of echo signal propagation through the cloud represented by semi-infinity homogeneous layer are discussed. The contribution of multiple scattering to a ground-based and a spaceborne monostatic lidar returns from clear atmosphere obscured by cumulus, stratus or cirrus clouds is assessed at the wavelength of 0.532 μm. The significant presence of multiple scattering in lidar returns and its dependence on the characteristics of the sounded clouds are demonstrated. High anisotropy of scattering in the forward direct ion by polydispersions of large nonspherical ice crystals is the basis of a tangible effect of multiple scattering for small values of the lidar receiver field of view. The radiation scattered by the crystal particles within a narrow cone around the forward direct ion is predominant and is greater than the corresponding values for scattering on water droplets. For cumulus and stratus clouds, the contribution of triple-scattered photons and higher to the total echo signal increases with increasing field of view of the receiver. The magnitude of multiple scattering effects is also seen to be largely determined by the optical depth across the receiver field of view at the cloud.

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“…The cirrus clouds consist predominantly of ice crystal particles. The scattering properties of the particles and their size and shape distributions have been widely studying last years by both direct measurements and some remote sensing techniques 25 One of the most perspective remote techniques for studying the ice crystals is lidar measurements, a light source being located either on the ground 6,7 or on satellites 8,9 Hexagonal ice crystals, i.e. solid hexagonal columns and plates, are important types of particles in cirrus clouds.…”

Section: Introductionmentioning

confidence: 99%

<title>Backscattering by hexagonal ice crystals</title>

1999

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Backscattering of light by hexagonal ice crystals has been calculated within the framework of the ray-tracing method. It is shown that the backscattermg properties of hexagonal ice crystals including polarization depend crucially on the particle orientations. A gigantic peak of backscattering is found at the tilt of the particles at the angle of 32.5 degrees. This peak has been explained by the peculiar "effect of the corner reflector" taking place in the solid hexagonal cylinders.

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Multiple scattering from clear atmosphere obscured by transparent crystal clouds in satellite-borne lidar sensing

Cited by 8 publications

References 3 publications

Multiple-scattering effects on single-wavelength lidar sounding of multi-layered clouds

Multiple-scattering effects on single-wavelength lidar sounding of multi-layered clouds

Modeling of laser pulse propagation in clouds taking into account multiple scattering

<title>Backscattering by hexagonal ice crystals</title>

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