Investigation of particle and molecular extinction effects in remote sensing by ultraviolet DIAL in the lower atmosphere

TL;DR

This paper theoretically investigates how particle and molecular extinction affect UV-DIAL remote sensing near the ground, finding aerosol extinction dominates and systematic errors are minimal despite wavelength separation.

Contribution

It provides a detailed analysis of extinction effects in UV-DIAL, highlighting the dominance of aerosol extinction and negligible systematic errors from aerosol scattering.

Findings

Aerosol attenuation varies smoothly with wavelength.

Systematic errors from aerosol scattering are negligible.

Molecular scattering becomes significant at higher altitudes and wavelengths above 310 nm.

Abstract

This study presents theoretical investigation of the effects of particle and molecular extinction in horizontal remote sensing near the ground for several visibilities at UV wavelengths by neglecting the spatial inhomogeneity of aerosol in the atmosphere and taking into account the dependence of refracting on air temperature and pressure. Due to weak attenuation of oxygen and other gaseous atmospheric constituents in this region, we have only considered the effect of ozone in calculation. The results are important to estimate systematic errors in measuring gas concentration introduced by large wavelength separation in UV-DIAL. The total attenuation (km-1) at wavelengths is listed in the form of a table from 200 to 400 nm for several values of visibilities. It is found the aerosol attenuation in UV region varies quite smoothly with wavelength and therefore systematic error caused by aerosol scattering is negligible in remote sensing by UV-DIAL even with large wavelength separation. Moreover, it has been found that only aerosol extinction is dominant in lidar remote sensing in the lower atmosphere in UV region. In large altitude that aerosol concentration is lower; the molecular scattering is important especially for wavelengths larger than 310 nm.