title: An analysis of aerosol liquid water content and related impact factors in Pearl River Delta.
abstract: Aerosol liquid water content (ALWC) has an important effect on atmospheric visibility as well as heterogeneous chemical reactions. In this paper, we used the data size-resolved particle hygroscopic growth factor, and particle number size distribution (PNSD) obtained from H-TDMA and SMPS to compute ALWC at the Guangzhou Panyu site from the winter of 2014 and the spring of 2015. The corresponding results were relatively consistent with the trend for ALWCISOcalculated from the ISORROPIA II thermodynamic equilibrium model based on the measurement of aerosol water-soluble ionic compositions obtained from MARGA, with a linear fit yielding an R2value of 0.76. The fact that ALWCHTDMAwas somewhat higher than ALWCISOat low RH values was at least partially attributable to the fact that effects resulting from organic matter hygroscopicity were not taken into account when computing ALWCISO. In sensitivity testing, ambient relative humidity, PNSD and particle hygroscopicity were all found to affect ALWC, in that order. Particles of different modes made different contributions to ALWC with the contributions of nuclear, Aitken, accumulation and coarse modes assessed at <1%, 3%, 85% and 12%, respectively, indicating that the contribution of accumulation mode particles to ALWC dominated among all the aerosol particle modes. During clean processes, decreases in relative humidity and PM2.5both resulted in a decrease in ALWC. During the pollution processes, calm winds caused local particle accumulation, with ALWC increasing as RH increased. Intraday trends in ALWC and relative humidity were consistent, with minimum mean values observed in the afternoon due to low ambient relative humidity inhibiting an increase in ALWC. However, diurnal variation of aerosol hygroscopicity and ALWC tended to be somewhat anti-correlated, indicating that diurnal changes in aerosol hygroscopicity are not a primary factor resulting in ambient AWLC changes.
authors.affiliation: Key Laboratory of Regional Numerical Weather Prediction, Guangzhou Institute of Tropical and Marine Meteorology, China Meteorological Administration, Guangzhou 510680, China; Guangdong Ecological Meteorology Center, Guangzhou 510640, China. Electronic address: hbtan@grmc.gov.cn.
authors.forename: Haobo
authors.initials: H
authors.lastname: Tan
authors.affiliation: Sun Yat-Sen University, Guangzhou, China.
authors.forename: Mingfu
authors.initials: M
authors.lastname: Cai
authors.affiliation: Sun Yat-Sen University, Guangzhou, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Fan
authors.affiliation: Sun Yat-Sen University, Guangzhou, China.
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.affiliation: Key Laboratory of Regional Numerical Weather Prediction, Guangzhou Institute of Tropical and Marine Meteorology, China Meteorological Administration, Guangzhou 510680, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Li
authors.affiliation: Hong Kong Observatory, Hong Kong, China.
authors.forename: P W
authors.initials: PW
authors.lastname: Chan
authors.affiliation: Key Laboratory of Regional Numerical Weather Prediction, Guangzhou Institute of Tropical and Marine Meteorology, China Meteorological Administration, Guangzhou 510680, China.
authors.forename: Xuejiao
authors.initials: X
authors.lastname: Deng
authors.affiliation: Jinan University, Guangzhou, China.
authors.forename: Dui
authors.initials: D
authors.lastname: Wu
keywords: Aerosol hygroscopicity; Aerosol liquid water content; Pearl River Delta