Stratospheric Aerosol Particles Size Distribution Based on Multi-Color Polarization Measurements of the Twilight Sky

TL;DR

This study uses multi-color polarization measurements of twilight sky to determine the size distribution of stratospheric aerosol particles, confirming previous results and providing two independent analysis methods.

Contribution

It introduces a polarization-based method for analyzing stratospheric aerosol size distribution, validated against existing colorimetric and remote sensing data.

Findings

Mean particle radius ~0.1 micrometers

Size distribution consistent with in situ data

Method confirms previous colorimetric results

Abstract

Polarization measurements of the twilight background with Wide-Angle Polarization Camera (WAPC) are used to detect the depolarization effect caused by stratospheric aerosol near the altitude of 20 km. Based on a number of observations in central Russia in spring and summer 2016, we found the parameters of lognormal size distribution of aerosol particles. This confirmed the previously published results of the colorimetric method as applied to the same twilights. The mean particle radius (about 0.1 micrometers) and size distribution are also in agreement with the recent data of in situ and space-based remote sensing of stratospheric aerosol. Methods considered here provide two independent techniques of the stratospheric aerosol study based on the twilight sky analysis.