Passive Remote Study of the Aerosol in the Upper Atmosphereof the Earth

Abstract

Climate changes on planet Earth are mainly caused by disturbances in the energy balance of the Sun-Earth system. This process is the result of both natural changes in nature and the influence of anthropogenic factors. The combined effect of these factors can lead to threatening phenomena for mankind - a decrease in the power of the ozone layer, the formation of “ozone holes” and global warming on the planet and other disasters. The study of the causes of these factors and the determination of their relative contribution is one of the pressing problems of our time.

To clarify these reasons, the Main Astronomical Observatory of the National Academy of Sciences of Ukraine (MAO NASU) proposed to conduct a satellite polarimetric experiment in the ultraviolet region of the spectrum on passive remote sensing of the upper atmosphere of the Earth in order to obtain information about the physical properties of the stratospheric aerosol according to the results of polarimetric and photometric measurements. To implement this experiment, the joint efforts of three organizations (the Main Astronomical Observatory of the National Academy of Sciences of Ukraine, the National Technical University of
Ukraine “KPI” and the Lviv Polytechnic National University) developed and created a working model of the onboard miniature polarimeter (UVP) operating in the ultraviolet spectral range of wavelengths. Compared with other similar experiments, the proposed method for remote study of aerosol from space allows to cut off the influence of the tropospheric component of the atmosphere and the Earth’s surface and, as a result, to isolate the polarization component of the stratospheric aerosol for research in its pure form.

To confirm the correctness of the chosen research ideology, the model created of the current on-board UVP was created and carefully examined at a specially designed and manufactured stand, and then adapted for ground-based observations and mounted on the AZT-2 astronomical telescope (MAO NASU). On September 26, 2017, cloudless sky observations were conducted on the AZT-2 telescope in the MAO NAS of Ukraine and data on changes in the Stokes polarimetric parameters were obtained. Processing the obtained data showed that the polarization on the phase curve varies from -3 to 32%. A comparison analysis of the observational
data with the calculation results shows that our observations best fit the calculations for the particle size rо = 0.16 μm and the real part of the refractive index nr = 1.33 in the troposphere and up to 1.42 for the stratosphere.

Therefore, it can be concluded that even such an approximate analysis of polarization observations of a cloudless sky under terrestrial conditions, both during the day and after sunset, indicates the possibility of studying the physical characteristics of the aerosol in the troposphere and stratosphere, respectively. And conducting a space experiment to study changes in the polarization component of the stratospheric aerosol in the ozone layer of the Earth will allow us to obtain data, the analysis of which will make it possible to judge the causes of the change in the thickness of this layer in the Earth’s atmosphere.