Simultaneous retrievals of biomass burning aerosols and trace gases from the ultraviolet to near-infrared over northern Thailand during the 2019 pre-monsoon season

Abstract

With the advent of spaceborne spectroradiometers in a geostationary constellation, measuring high spectral resolution ultraviolet-visible (UV-VIS) and selected near-/shortwave-infrared (NIR/SWIR) radiances can enable the probing of the life cycle of key atmospheric trace gases and aerosols at higher temporal resolutions over the globe. The UV-VIS measurements are important for retrieving several key trace gases (e.g., O 3 , SO 2 , NO 2 , and HCHO) and particularly for deriving aerosol characteristics (e.g., aerosol absorption and vertical profile). This study examines the merit of simultaneous retrievals of trace gases and aerosols using a ground-based spectroradiometer covering the UV-NIR to monitor their physicochemical processes and to obtain reliable aerosol information for various applications. During the 2019 pre-monsoon season over northern Thailand, we deployed a ground-based SMART-s (Spectral Measurements for Atmospheric Radiative Transferspectroradiometer) instrument, which is an extended-range Pandora with reliable radiometric calibration in the 330-820 nm range, to retrieve remotely sensed chemical and aerosol properties for the first time near biomass burning sources. The high spectral resolution (∼ 1.0 nm full width half maximum with ∼ 3.7 × oversampling) of sun and sky measurements from SMART-s provides several key trace gases (e.g., O 3 , NO 2 , and H 2 O) and aerosol properties covering the UV where significant light absorption occurs by the carbonaceous particles. During the measurement period, highly correlated total column amounts of NO 2 and aerosol optical thickness (τ aer ) retrieved from SMART-s (correlation coefficient, R = 0.74) indicated their common emissions from biomass burning events. The SMART-s retrievals of the spectral single scattering albedo (ω 0 ) of smoke aerosols showed an abrupt decrease in the UV, which is an important parameter dictating photochemical processes in the atmosphere. The values of ω 0 and column precipitable water vapor (H 2 O) gradually increase with the mixing of biomass burning smoke particles and higher water vapor concentrations when approaching the monsoon season. The retrieved ω 0 and weighted mean radius of fine-mode aerosols from SMART-s showed positive correlations with the H 2 O (R = 0.81 for ω 0 at 330 nm and 0.56 for the volume-weighted mean radius), whereas the real part of the refractive index of fine-mode aerosol (n f ) showed negative correlations (R = −0.61 at 330 nm), which suggest that aerosol aging processes including hygroscopic growth (e.g., humidification and cloud processing)Published by Copernicus Publications on behalf of the European Geosciences Union. 11958 U. Jeong et al.: Simultaneous retrievals of biomass burning aerosols and trace gases over Thailand can be a major factor affecting the temporal trends of aerosol optical properties. Retrieved n f and ω 0 were closer to those of the water droplet (i.e., n f of about 1.33 and ω 0 of about 1.0) under lower amounts of NO 2 during the measurement period; considering that the NO 2 a...

Estimation of Inactivation time for the SARS-CoV-2 virus from the UV biometer in South Korea

“…The Pandora spectrometer observes the spectral radiance ranged from 280 to 525 nm with a spectral resolution of 0.6 nm (e.g., Tzortziou et al 2012 ). However, the Pandora spectrometer is mainly observed direct solar light to measure the total column amount of trace gases and scattered light for vertical information of atmospheric compositions (e.g., Herman et al 2018 ; Jeong et al 2022 ). Due to the unstable observation datasets from the Brewer spectrometer in South Korea, the broadband UV observation instrument, namely, the UV biometer, was used in this study.…”