Detection of Molecular Scattering Field from a Polarization Analysis of the Sky Background during Transitive Twilight and Temperature Measurements near the Stratopause

The simplest version of the method of detecting the single molecular scattering field based on the polarization measurements of the twilight sky background by all-sky cameras has been considered. The method can be used during transitive twilight (with solar zenith angles of 94°–98°), when effective single scattering occurs in the upper stratosphere and lower mesosphere. The long-term measurements conducted using this method in the Moscow region and Apatity make it possible to determine the temperature of these atmospheric layers and estimate the contribution and properties of multiple scattering during the transitive twilight.     

Optical properties of the undisturbed mesosphere from wide-angle twilight sky polarimetry

The paper describes the first results of all-sky polarization measurements of the twilight background started in central Russia in the very beginning of summer 2011. Time-frequency data of the sky intensity and polarization over a wide range of sky point zenith distances are used to separate single and multiple scattering and construct the altitude dependence of the scattering coefficient and polarization in the mesosphere (altitudes from 60 to 90 km) at different angles. The undisturbed structure of the mesosphere without noticeable aerosol stratification on observation days makes it possible to estimate the temperature of the atmosphere at these altitudes.     

Erratum to: Postvolcanic Aerosols: Measurements of Altitude and Particle Sizes with Twilight-Sky Polarimetry

Cosmic Research - An Erratum to this paper has been published: https://doi.org/10.1134/S0010952521110010     

Polarization Studies of Contribution of Aerosol Scattering to the Glow of Twilight Sky

The paper is devoted to studies and a quantitative estimation of the influence of scattering of direct solar radiation by particles of tropospheric aerosols in the period of light twilight, close to sunrise and sunset. Polarization measurements of the twilight sky in two broad spectral bands lying near the standard bands V and R form the basis of these studies. The measurements were carried out in 2002 and 2003 at the Southern Laboratory (Crimea) of the Sternberg Astronomical Institute. The twilight period during which the single aerosol scattering becomes significant is isolated. The character of its influence on the intensity and polarization of the twilight sky is demonstrated. A method is suggested to evaluate polarization of the single aerosol scattering and its contribution to the general brightness of the twilight sky background. The method is based on differential characteristics of the background near the zenith and on their correlations with each other.     

高超声速流的电子束诊断法(英文)

本文描述用电子束辉光法测量高超声速流中平均密度、速度以及密度变化特征的物理原理和过程。对此法用于平板上激波层稳定性问题的适用范围和限制条件作了分析。内容通过风洞实验结果加以说明。     

Scattering function of tropospheric aerosol according to the data of polarimetry of the twilight and night sky background

The paper contains the photometric and polarimetric analysis of the sky background near the zenith during the twilights and the nights of different years and seasons. The period of enhanced tropospheric aerosol content during the summer 2009 is noticed. The aerosol scattering of solar emission is separated from the total twilight sky background, and similar data on lunar emission is taken from the night sky background. The results are compared with the data of relatively clear troposphere of winter 2006. The observational data are used to construct the polarization scattering function of tropospheric aerosol particles during the nighttime.     

Wide-angle polarimetry of the night sky: Measurements of atmospheric glow and zodiacal light

This paper is devoted to the analysis of the results of wide-angle polarimetric observations of the night sky, which has been carried out in December 2002 in the Southern Laboratory of Shternberg State Astronomical Institute (Crimea, Ukraine) in a color band close to the V band (the effective wavelength is 5250 ). We propose a method with the help of which the sky light was separated into basic components: the atmospheric glow, emission of weak stars, and the zodiacal light. The polarization map of extra-atmospheric emission of five sky zones close to the ecliptic is constructed, and it is shown that polarization of the sky background far from the antisolar point is determined, in the main, by the zodiacal light. For each observational period, the time dependence of the atmospheric luminosity and absorption is obtained.Translated from Kosmicheskie Issledovaniya, Vol. 43, No. 1, 2005, pp. 19–26.Original Russian Text Copyright © 2005 by Ougolnikov, Maslov.     

Multicolor Polarimetry of the Twilight Sky: The Role of Multiple Light Scattering as a Function of Wavelength

This paper is devoted to the investigation of the role of multiply scattered light of different wavelengths in clear twilight, as well as to the influence of multiple scattering and scattering by atmospheric aerosol particles on the polarization of the twilight sky background during this period. The work is based on wide-angle polarimetric CCD-observations of the twilight sky near zenith in the U, B, V, and R bands, which were carried out in summer 2000 at the South Laboratory of the Moscow Shternberg Astronomical Institute. Based on the data obtained, we have determined the fraction of single-scattered light in clear twilight in the zenith for the U, B, and V bands and have estimated the lower limit of this value for the R band. The analysis of color and polarimetric evolution of the sky background was made taking into account single and multiple scattering properties. The characteristic height of the upper boundary of the tropospheric aerosol layer in the Earth's atmosphere was also obtained.     

Studies of the stratosphere aerosol layer based on polarization measurements of the twilight sky

The paper is devoted to an analysis of observational manifestations of the aerosol layer in the Earth’s stratosphere and to a method of determining their optical properties. It is based on polarization measurements of the twilight sky background in the zenith vicinity and in a broad spectral band with an effective wavelength of 5250 Å. An increased abundance of the stratosphere aerosol was found in December 2006 for the first time in several years of observation. The suggested method allows one to determine the ratio of radiation scattering coefficients by the stratosphere aerosol and by air molecules, as well as the degree of polarization of aerosol scattering in the stratosphere. The appearance of the stratosphere aerosol is associated with explosive eruption of Rabaul volcano having occurred in the beginning of October 2006.     

Investigations of the Background Stratospheric Aerosol Using Multicolor Wide-Angle Measurements of the Twilight Glow Background

The first results of multiwave measurements of twilight background and the all-sky camera with a color (RGB) CCD matrix conducted in the spring and summer of 2016 in Central Russia (55.2° N, 37.5° E) have been discussed. The observations reveal the effect of aerosol scattering at heights of up to 35 km, which is substantially enhanced in the long-wave part of the spectrum (R band with an effective wavelength of 624 nm). An analysis of the behavior of the sky color during light period of twilight with allowance for the absorption by ozone in the Chappuis bands make it possible to restore the angular dependences of the intensity of the aerosol scattering of the light. This is used to determine the parameters of the lognormal distribution of aerosol particles over their sizes with a mean radius of 0.08 μm and a width of 1.5–1.6 for the stratospheric height interval.