Columnar Aerosol Optical Property Characterization and Aerosol Typing Based on Ground-Based Observations in a Rural Site in the Central Yangtze River Delta Region

Yong Xie,Qiaoli Hu,Tiexi Chen,Wen Shao,Yi Su,Xingfa Gu

doi:10.3390/rs14020406

Abstract

Accurate and updated aerosol optical properties (AOPs) are of vital importance to climatology and environment-related studies for assessing the radiative impact of natural and anthropogenic aerosols. We comprehensively studied the columnar AOP observations between January 2019 and July 2020 from a ground-based remote sensing instrument located at a rural site operated by Central China Comprehensive Experimental Sites in the center of the Yangtze River Delta (YRD) region. In order to further study the aerosol type, two threshold-based aerosol classification methods were used to investigate the potential categories of aerosol particles under different aerosol loadings. Based on AOP observation and classification results, the potential relationships between the above-mentioned results and meteorological factors (i.e., humidity) and long-range transportation processes were analyzed. According to the results, obvious variation in aerosol optical depth (AOD) during the daytime, as well as throughout the year, was revealed. Investigation into AOD, single-scattering albedo (SSA), and absorption aerosol optical depth (AAOD) revealed the dominance of fine-mode aerosols with low absorptivity. According to the results of the two aerosol classification methods, the dominant aerosol types were continental (accounting for 43.9%, method A) and non-absorbing aerosols (62.5%, method B). Longer term columnar AOP observations using remote sensing alongside other techniques in the rural areas in East China are still needed for accurate parameterization in the future.

Highlights

IntroductionInvestigation into AOD, single-scattering albedo (SSA), and absorption aerosol optical depth (AAOD) revealed the dominance of fine-mode aerosols with low absorptivity
aerosol optical properties (AOPs), aerosol typing, and the relationships between AOPs and meteorological factors (i.e., relative humidity (RH)), analysis was conducted based on the columnar AOP observations from a rural site near the center of the Yangtze River Delta (YRD) during January 2019–July 2020, filling the gap of columnar AOP
aerosol optical depth (AOD) variation during the daytime, an obvious symmetrical distribution pattern was observed, with the lowest fine-/coarse-mode AOD around 12 p.m., and the highest in the morning and afternoon, as a result of meteorological and anthropogenic factors; (2) Strong wavelength dependence was observed for fine-/coarse-mode AOD, absorption aerosol optical depth (AAOD), and single-scattering albedo (SSA), indicating the potential dominance of efficiently scattering fine-mode aerosols; (3) Aerosol classification analysis reveals the dominance of the urban industry aerosol type, which exhibited low absorptivity throughout the study period

Summary

Introduction

Investigation into AOD, single-scattering albedo (SSA), and absorption aerosol optical depth (AAOD) revealed the dominance of fine-mode aerosols with low absorptivity. Aside from AOP observations, much attention is paid to the classification of columnar aerosols, so as to further learn about the long-range transportation and potential source(s) of aerosol particles [12,13,14]. These efforts include aerosol typing and component analysis studies carried out directly from measured radiance [14], or indirectly, based on AOP inversions (e.g., AAOD) [15,16,17].

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Conclusion