Characteristics of Aerosol and Cloud over the Central Plain of North China in Summer

The vertical distribution of aerosols and clouds is a key issue in the indirect climate effects of aerosols. Based on the aerosol and cloud droplet number concentration data observed by 6 aircrafts over the central plain of North China from July to August in 2018, the vertical distribution and spectral characteristics of aerosols and clouds are studied. The results show that the mean value of aerosol number concentration ( N_a ) of this area is higher than that in Central China, the in-cloud aerosol number concentration (N_acc) accounts for over 80% of the total concentration, and the mean particle diameter ( D_m ) is between 0.12 and 0.52 μm, which means fine particles contribute the largest proportion. The aerosol number concentration decreases with the height. The total aerosol number concentration is higher with middle and high stratus comparing to low-level stratus. The vertical distribution of N_a is significantly affected by atmospheric stratification, as inversion temperature layer block the vertical transport of aerosols. The vertical distribution of mean diameter below 3500 m is relatively stable, with an average of 0.23 μm, while increases with the height above 3500 m. The vertical distribution of aerosol particle mean diameter at high altitude (above 2000 m) is greatly affected by relative humidity. Compared with the vertical distribution of aerosol number concentration and mean diameter, the horizontal variety is smaller. In low-level stratus, the cloud droplet number concentration (N_c) is large, and the liquid water content (L) is small. In middle and high stratus, the cloud droplet number concentration is small, and the liquid water content is large. The probability distribution function of cloud droplet number concentration and liquid water content are bimodal distribution, and the probability distribution function of cloud droplet effective radius (R_e) show a single mode. The distribution of aerosol number concentration spectrum shows multi-peak distribution, and the average aerosol spectrum show three-peak distribution. The distribution of cloud droplet number concentration spectrum shows a single peak, which appears at the scale of 9-16 μm, and the spectral width of cloud droplets is 50 μm. The parameter characteristics of aerosol spectral distribution obtained by fitting aerosol spectral distribution can provide an important in situ measurement basis for improving the parameterized schemes such as regional climate model and aerosol-cloud model.