Analyzing the Characteristics of Cloud Condensation Nuclei (CCN) in Hebei, China Using Multi-Year Observation and Reanalysis Data

Hengqi Wang,Yiran Peng,Meng Zhang,Jing Duan

doi:10.3390/atmos13030468

Hengqi Wang, Yiran Peng + Show 2 more

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https://doi.org/10.3390/atmos13030468

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Abstract

The study of the characteristics and variations of cloud condensation nuclei (CCN) plays an important role in understanding the effects of aerosol–cloud interactions. This paper selected observation data in a city region of Shijiazhuang in North China from 2005 to 2007, along with the corresponding MERRA-2 and ERA5 data, to analyze the characteristics of CCN, sort the factors affecting the diurnal variation of CCN number concentration (NCCN) according to their importance, and build the relationship between NCCN and supersaturation (SS) in the heavily polluted region. The results show that there was a bimodal distribution of a daily time series for NCCN in Shijiazhuang, China. By calculating the correlation between CCN and pollutants observed in winter 2007, we identified that the dominant factor for peaks of NCCN is SO2 in the morning but NO2 in the evening. We also ranked the factors affecting the diurnal variation of NCCN by using observation and reanalysis data and found that the concentration of pollutants is the greatest impact factor in summer, but the atmospheric stability is the greatest factor in winter. Finally, we determined the relationship between NCCN and SS according to the Twomey formula (NCCN=cSSk) and found there was a reasonable value range (i.e., 0.5~0.7) for the parameter k in East and North China. Specifically, it is more reasonable for k to be 0.5 in summer and 0.7 in winter.

Highlights

IntroductionPublished: 14 March 2022The multiphase system composed of solid and liquid particles suspended in the air is called aerosol
Considering the number concentration (NCCN) data with SS = 0.3 % had more valid data samples, we selected the NCCN under this supersaturation to analyze the characteristics of diurnal variation
This study used multi-year data observed in Shijiazhuang from 2005 to 2007 and the reanalysis data (MERRA-2 and ERA5) to investigate the characteristics of cloud condensation nuclei (CCN), sort the factors affecting the diurnal variation of NCCN according to their importance, and build the relationship between NCCN and SS in the heavily polluted region

Summary

Introduction

Published: 14 March 2022The multiphase system composed of solid and liquid particles suspended in the air is called aerosol. Particle size, and number concentration have important effects on the radiation budget, clouds, and precipitation in the earth system [1–4]. A part of aerosols can indirectly affect cloud radiative properties [2] and precipitation processes [5] by influencing the cloud droplet size/number of warm stratus clouds, namely aerosol–cloud interaction. These aerosols are called cloud condensation nuclei (CCN). Due to the complexity of aerosol–cloud interaction and cloud/rain processes, there are large uncertainties in estimating the effect of aerosol on climate using global climate models (GCM) [6–8]. To better evaluate climate model simulation on aerosol–cloud interaction and reduce the uncertainty, it is necessary to conduct a more in-depth study on the characteristics of CCN over large-scale and long-term spatial-temporal domains

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