A closure study of aerosol optical properties at a regional background mountainous site in Eastern China

Liang Yuan; Yan Yin; Hui Xiao; Xingna Yu; Jian Hao; Kui Chen; Chao Liu

doi:10.1016/j.scitotenv.2016.01.205

A closure study of aerosol optical properties at a regional background mountainous site in Eastern China

Sci Total Environ. 2016 Apr 15:550:950-960. doi: 10.1016/j.scitotenv.2016.01.205. Epub 2016 Feb 4.

Authors

Liang Yuan¹, Yan Yin², Hui Xiao³, Xingna Yu¹, Jian Hao³, Kui Chen³, Chao Liu¹

Affiliations

¹ Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science & Technology, Nanjing 210044, China; Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, China.
² Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science & Technology, Nanjing 210044, China; Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, China. Electronic address: yinyan@nuist.edu.cn.
³ Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, China.

PMID: 26851881
DOI: 10.1016/j.scitotenv.2016.01.205

Abstract

There is a large uncertainty in evaluating the radiative forcing from aerosol-radiation and aerosol-cloud interactions due to the limited knowledge on aerosol properties. In-situ measurements of aerosol physical and chemical properties were carried out in 2012 at Mt. Huang (the Yellow Mountain), a continental background mountainous site in eastern China. An aerosol optical closure study was performed to verify the model outputs by using the measured aerosol optical properties, in which a spherical Mie model with assumptions of external and core-shell mixtures on the basis of a two-component optical aerosol model and high size-segregated element carbon (EC) ratio was applied. Although the spherical Mie model would underestimate the real scattering with increasing particle diameters, excellent agreement between the calculated and measured values was achieved with correlation coefficients above 0.98. Sensitivity experiments showed that the EC ratio had a negligible effect on the calculated scattering coefficient, but largely influenced the calculated absorption coefficient. The high size-segregated EC ratio averaged over the study period in the closure was enough to reconstruct the aerosol absorption coefficient in the Mie model, indicating EC size resolution was more important than time resolution in retrieving the absorption coefficient in the model. The uncertainties of calculated scattering and absorption coefficients due to the uncertainties of measurements and model assumptions yielded by a Monte Carlo simulation were ±6% and ±14% for external mixture and ±9% and ±31% for core-shell mixture, respectively. This study provided an insight into the inherent relationship between aerosol optical properties and physicochemical characteristics in eastern China, which could supplement the database of aerosol optical properties for background sites in eastern China and provide a method for regions with similar climate.

Keywords: Aerosol optical properties; Closure study; Mixing state; Mt. Huang; Size-segregated; Uncertainty.

Publication types

Research Support, Non-U.S. Gov't