Vertical profiles of cloud condensation nuclei number concentration and its empirical estimate from aerosol optical properties over the North China Plain

Abstract

Abstract. To better understand the characteristics of aerosol activation ability and optical properties, a comprehensive airborne campaign was conducted over the North China Plain (NCP) from 8 May to 11 June 2016. Vertical profiles of cloud condensation nuclei (CCN) number concentration (NCCN) and aerosol optical properties were measured simultaneously. Seventy-two-hour air mass back trajectories show that during the campaign, the measurement region was mainly influenced by air masses from the northwest and southeast. Air mass sources, temperature structure, anthropogenic emissions, and terrain distribution are factors influencing NCCN profiles. Cloud condensation nuclei spectra suggest that the ability of aerosol to activate into CCN is stronger in southeasterly air masses than in northwesterly air masses and stronger in the free atmosphere than near the surface. Vertical distributions of the aerosol scattering Ångström exponent (SAE) indicate that aerosols near the surface mainly originate from primary emissions consisting of more fine particles. The long-distance transport decreases SAE and makes it vary more in the free troposphere than near the surface. To parameterize NCCN, the equation NCCN=10β⋅σγ is used to fit the relationship between NCCN and the aerosol scattering coefficient (σ) at 450 nm. The fitting parameters β and γ have linear relationships with the SAE. Empirical estimates of NCCN at 0.7 % water vapor supersaturation (SS) from aerosol optical properties are thus retrieved for the two air masses: NCCN=10-0.22⋅SAE+2.39⋅σ0.30⋅SAE+0.29 for northwesterly air masses and NCCN=10-0.07⋅SAE+2.29⋅σ0.14⋅SAE+0.28 for southeasterly air masses. The estimated NCCN at 0.7 % SS agrees with that measured, although the performance differs between low and high concentrations in the two air masses. The results highlight the important impact of aerosol sources on the empirical estimate of NCCN from aerosol optical properties.

A first global height-resolved cloud condensation nuclei data set derived from spaceborne lidar measurements

“…The concentration of such particles varies with geographical location and, as per the findings from surface in situ measurements, can range from about 10 cm −3 under pristine conditions to as much as 10 5 cm −3 in polluted urban air masses (Schmale et al, 2018). Similar orders of magnitude of variation in CCN concentrations are also seen in the vertical dimension, with the highest concentrations close to the surface and only a few particles in the upper troposphere (Brock et al, 2021;Zhang et al, 2022). Given the wide range of CCN concentrations, global information on the horizontal and vertical distribution of CCN is necessary to accurately quantify the impact of ACIs on climate (Bellouin et al, 2020;Quaas et al, 2020).…”

Vertical Profiles of Particle Number Size Distribution and Variation Characteristics at the Eastern Slope of the Tibetan Plateau

“…Previous research has indicated that variations in air masses can result in spatiotemporal discrepancies in the PNSD and aerosol optical properties [39,65,66]. In order to gain a deeper understanding of the sources of air masses and the pathways of aerosol transport within the study area, 72 h air mass back trajectories for air masses at 1 km were analyzed using the NOAA Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model [67].…”

Comparative Analysis of Aerosol Vertical Characteristics over the North China Plain Based on Multi-Source Observation Data

“…Urbanization, industrialization, and the rapid development of the economy initiated an exceptionally high variable aerosol loading in eastern China, especially in the North China Plain (NCP) region [1][2][3][4]. Absorbing soot and organic aerosols from fossil fuel or biomass burning probably contributes significantly to this region's heavy pollution [5,6].…”