Eleonora P. Zege

New algorithm to retrieve the effective snow grain size and pollution amount from satellite data

Abstract This paper presents a new simple and efficient algorithm to retrieve the effective snow grain size and soot concentration from spectral reflectance on snow measured by optical instrument on a satellite. This algorithm was recently developed and will be used for integrated ice–atmosphere–ocean monitoring in the framework of the DAMOCLES program. The algorithm is based on an analytical approach to snow optics. In this approach snow is considered as a close-packed medium with irregularly shaped grains rather than with independent spherical particles. Unlike the known conventional algorithms, the developed algorithm uses no a priori snow optical model. The analytical nature of this algorithm provides a very fast inversion of the reflection data. The developed algorithm was realized and validated for the GLI and MODIS instruments. The algorithm can be generalized for other satellite instruments with appropriate spectral channels. Finally, the results of verifications using a computer simulation are discussed.

Approximate theory of linearly polarized light propagation through a scattering medium

Abstract This work continues developing the analytical theory of polarized light transfer through scattering media and simplification of the Greens matrix of the problem with splitting the equations for Greens matrix elements started in our previous paper (Zege EP, Chaikovskaya LT. JQSRT 1996;55:19–31). The specific problem is the propagation of linearly polarized light, which is governed by the central block of the Greens matrix with elements (2,2), (2,3), (3,2), (3,3). The small parameter of the propagation problem is a value, which characterizes the rotation of the polarization plane in a near-forward scattering event. For a macroscopically isotropic medium with large scattering particles this value is always small. A new set of transfer equations for linearly polarized light propogation and scattering is given, splitting of this equation having been achieved. The more forward elongated the medium phase function is the more accurate the solution to the problem. An effective iteration procedure to solve the original set of equations is suggested. It is shown that the linearly polarized light transfer problem reduces to a scalar problem and can be solved analytically for small-angle forward propagation and near-backward scattering.

Analytical modeling of Raman lidar return, including multiple scattering

An analytical approach to modeling Raman lidar return with multiple scattering in presented. This approach is based on a small-angle quasi-single-scattering approximation developed earlier for elastic lidar sounding. An approximation of isotropic backscattering for the Raman-scattering case is proposed and tested. The computed results are presented and compared with known data. The approximation was found to be quite simple and provided a high accuracy of Raman lidar return calculations.

Polarization of multiply scattered lidar return from clouds and ocean water

An analytical solution to polarized lidar return, including multiple scattering from stratified media with large scatters, is developed and discussed.

Possibilities of warm cloud microstructure profiling with multiple-field-of-view Raman lidar.

The possibilities of cloud characteristics retrieval with multiple-field-of-view Raman lidar are considered. It has been shown that the Raman lidar return is sensitive to two cloud characteristics; the scattering coefficient and the effective droplet size. This sensitivity is studied and the optimal receiver fields-of-view (FOVs) for cloud sounding are recommended. The optimal FOV values are estimated to be approximately R/H (R, the collecting optics radius, H, the cloud altitude) to measure the scattering coefficient profiles, and approximately 0.01z/H for the droplet size measurements (z, the cloud thickness). The algorithm based on the iterative scheme and singular value decomposition as a regularization procedure is presented and verified using computer simulation. The recommendations for profile retrieval with variable altitude resolution are given.

Combined ground-based and satellite remote sensing of atmospheric aerosol and Earth surface in the Antarctic

The paper presents lecture materials given at the Nineteenth International Conference and School on Quantum Electronics “Laser Physics and Applications” (19th ICSQE) in 2016, Sozopol, Bulgaria and contains the results of the 10-year research of Belarusian Antarctic expeditions to study the atmospheric aerosol and Earth surface in Antarctica. The works focus on the studying variability and trends of aerosol, cloud and snow characteristics in the Antarctic and the links of these processes with the long range transport of atmospheric pollutants and climate changes.