Estimation of Surface Concentrations of Black Carbon from Long-Term Measurements at Aeronet Sites over Korea

Abstract

We estimated fine-mode black carbon (BC) concentrations at the surface using AERONET data from five AERONET sites in Korea, representing urban, rural, and background. We first obtained the columnar BC concentrations by separating the refractive index (RI) for fine-mode aerosols from AERONET data and minimizing the difference between separated RIs and calculated RIs using a mixing rule that can represent a real aerosol mixture (Maxwell Garnett for water-insoluble components and volume average for water-soluble components). Next, we acquired the surface BC concentrations by establishing a multiple linear regression (MLR) between in-situ BC concentrations from co-located or adjacent measurement sites, and columnar BC concentrations, by linearly adding meteorological parameters, month, and land-use type as the independent variables. The columnar BC concentrations estimated from AERONET data using a mixing rule well reproduced site-specific monthly variations of the in-situ measurement data, such as increases due to heating and/or biomass burning and long-range transport associated with prevailing westerlies in the spring and winter, and decreases due to wet scavenging in the summer. The MLR model exhibited a better correlation between measured and predicted BC concentrations than those based on columnar concentrations only, with a correlation coefficient of 0.64. The performance of our MLR model for BC was comparable to that reported in previous studies on the relationship between aerosol optical depth and particulate matter concentration in Korea. This study suggests that the MLR model with properly selected parameters is useful for estimating the surface BC concentration from AERONET data during the daytime, at sites where BC monitoring is not available.

Long-Term eBC Measurements with the Use of MAAP in the Polluted Urban Atmosphere (Poland)

“…The correlation between the concentration of eBC and the values of atmospheric pressure, relative humidity, and precipitation was weak or statistically insignificant (Table 3). Lack of a clear relationship between precipitation and relative humidity and eBC concentration may result from the fact that freshly emitted BC particles have a hydrophobic character; thus, they are excluded from liquid droplets or are associated with an insoluble phase [47,70,71]. Compared to the above-mentioned meteorological parameters, wind speed is more effective in reducing eBC concentration at the sampling site.…”

Inferring the absorption properties of organic aerosol in Siberian biomass burning plumes from remote optical observations

“…These estimates indicate, in particular, that the IRI of OA originating from biomass burning is strongly variable, ranging from virtually zero to almost 0.04 (at the 550 nm wavelength). Reported estimates of the MAE of OA (e.g., Alexander et al, 2008;Favez et al, 2009;Yang et al, 2009;Cheng et al, 2011;Chung et al, 2012a;Olson et al, 2015) have been derived, albeit in a much simpler way, mostly from in situ observations of the absorption coefficients and OA (or organic carbon, OC) mass concentration and are also very diverse, differing by orders of magnitude. Typically, such estimates involve strong assumptions about the spectral dependence of the BC absorption.…”

Long-term variation of aerosol optical properties associated with aerosol types over East Asia using AERONET and satellite (VIIRS, OMI) data (2012–2019)

“…The BC and BC + BrC fractions displayed different seasonal characteristics. In a previous study, the BC mass density at Yonsei_University was highest in spring and winter during 2011-2018 (Choi et al, 2020), which could explain why our study identified the highest BC + BrC fraction in spring. Compared with the characteristics of BC + BrC, the characteristics of BC were more similar to the distribution tendency of NA.…”