Preprints
https://doi.org/10.5194/egusphere-2023-2122
https://doi.org/10.5194/egusphere-2023-2122
09 Oct 2023
 | 09 Oct 2023

An observation-constrained estimation of brown carbon aerosol direct radiative effects

Yueyue Cheng, Chao Liu, Jiandong Wang, Jiaping Wang, Dafeng Ge, Caijun Zhu, Jinbo Wang, and Aijun Ding

Abstract. Brown carbon (BrC) is an organic carbon component with noticeable absorption in the ultraviolet and short visible wavelengths, which influences the global radiative balance. However, the assessment of BrC radiative effects remains a challenging task because of the scarcity of direct BrC observations and uncertainties in their chemical and optical properties. This study proposes a convenient method for estimating BrC radiative effects based on concise observational data. The light-absorbing properties of BrC obtained from aethalometer measurements and an optical separation method were combined with the simulated BrC optical properties to determine their mass concentrations. The aerosol optical depth (AOD) and mass concentration of PM10 were used to constrain the total and other aerosol contents, and the optical properties and concentrations were estimated using an optical closure study. Such a state-of-the-art combination of measurements and numerical models provides the primary variables for radiative transfer simulations to estimate the BrC radiative effects. We use observations over four months (from July 1 to November 18, 2021) in Nanjing (a megacity in East China) as an example. During the observational period, BrC absorption constitutes 8.7–34.1 % of the total aerosol absorption at 370 nm. In the atmosphere, BrC plays a warming role with its average instantaneous radiative forcing (RF) and standard deviation of 6.4 ± 3.4 W m-2, 29.2 % that of black carbon (BC). At the surface, the BrC-induced actinic flux (AF) attenuation was comparable to that caused by BC, accounting for over 40 % of BC effects in the UV range and almost 20 % in the visible range. Furthermore, the photosynthetically active radiation (PAR) caused by BrC is about 34.7 ± 9.7 % that caused by BC. These findings provide valuable insights into the understanding of BrC radiative effects and indicate the importance and necessity of better observation and modeling of BrC properties.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Share

Journal article(s) based on this preprint

11 Mar 2024
An observation-constrained estimation of brown carbon aerosol direct radiative effects
Yueyue Cheng, Chao Liu, Jiandong Wang, Jiaping Wang, Zhouyang Zhang, Li Chen, Dafeng Ge, Caijun Zhu, Jinbo Wang, and Aijun Ding
Atmos. Chem. Phys., 24, 3065–3078, https://doi.org/10.5194/acp-24-3065-2024,https://doi.org/10.5194/acp-24-3065-2024, 2024
Short summary
Download

The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Short summary
Brown carbon (BrC) is an important light-absorbing aerosol influencing the climate change. This...
Share