Study on the particle size distribution of summer dust aerosols in Jiayuguan gobi region, Gansu Province

doi:10.11755/j.issn.1006-7639-2026-02-0293

Abstract

Abstract:

Based on APS-3321 (Aerodynamic Particle Sizer), real-time and continuous measurements of particle size distributions in the 0.5-20 μm range of dust aerosols were conducted in a desert source area of Jiayuguan during August 2024. The number and mass concentrations and their spectral distribution characteristics of dust aerosol were comprehensively analyzed under different weather patterns by using threshold values of mass concentration method. The results show that the number concentrations of dust particle under clear-sky conditions presented a unimodal distribution, with the peak particle size of 0.626 μm. The number concentrations of dust particles under floating dust and blowing dust conditions exhibited a bimodal pattern, and the main peak particle sizes were both located at a submicron of 0.626 μm, while the secondary peak diameters were 1.114 μm and 1.286 μm respectively. By contrast, the number concentrations of dust aerosols under heavy dust events also displayed a bimodal distribution, and the main peak particle size was located at a coarse-mode of 1.486 μm, while the secondary peak was 0.583 μm, which differed from those under floating and blowing dust scenes. This indicated that heavy dust storm events contribute significantly to the number concentration of large coarse-sized particles in the desert source area of Jiayuguan. However, the mass concentrations of dust particles under clear-sky, floating and blowing dust conditions all showed a bimodal structure, and the main peak sizes were 4.371, 3.523 and 3.278 μm respectively, and the secondary peaks occurred at 19.810, 15.960 and 15.960 μm. By contrast, the mass concentrations of dust particles under heavy dust events exhibited a trimodal distribution, with the peak particle sizes of 4.371 μm, 6.264 μm and 13.820 μm. During the whole period, the average mass concentration under floating dust condition varied from 80 to 200 μg·m^-3, and the corresponding maximal concentrations under blowing and heavy dust events were 600 μg·m^-3 and 2 400 μg·m^-3, respectively, which occurred at 06:00-09:00 and 09:00-18:00. The occurrences of heavy dust events led to a significant decrease in the percentage of dust particles at 0.5-1.0 μm from 80.9% to 39.9%, but they didn’t remarkably alter the percentage proportion of the mass concentration of coarse-mode dust particles in Jiayuguan.

Key words: dust aerosol, size distribution, aerodynamic particle diameter, number concentration, mass concentration

摘要：

利用APS-3321型空气动力学粒径谱仪对嘉峪关戈壁区2024年8月0.5~20.0 μm粒径的沙尘气溶胶粒径谱开展连续观测，结合浓度阈值方法分析不同天气类型的沙尘气溶胶数浓度、质量浓度及谱分布特征。结果表明，晴天的沙尘气溶胶数浓度谱呈现单峰型分布，峰值粒径为0.626 μm；浮尘、扬沙天气呈双峰型分布，主峰值粒径均位于亚微米级的0.626 μm，次峰值分别为1.114、1.286 μm；相比而言，沙尘暴过程也呈现双峰分布，但主峰值粒径位于粗模态的1.486 μm，次峰值为0.583 μm。晴天、浮尘和扬沙天气的气溶胶质量浓度谱均呈现双峰结构，主峰值粒径分别为4.371、3.523、3.278 μm，对应次峰值的粒径分别为19.810、15.960、15.960 μm。而沙尘天气下其质量浓度谱呈现三峰型分布，峰值粒径分别为4.371、6.264、13.820 μm。观测期间，浮尘天气气溶胶平均质量浓度为80~200 μg·m^-3，扬沙天气主要出现在早晨06：00—09：00（北京时，下同），峰值为600 μg·m^-3，而沙尘暴天气主要出现在09：00—18：00，峰值达2 400 μg·m^-3。强沙尘天气导致0.5~1.0 μm粒径的气溶胶数浓度占比由80.9%减小至39.9%，但并未明显改变粗粒径段沙尘的质量浓度百分占比。

关键词: 沙尘气溶胶, 粒径谱分布, 空气动力学直径, 数浓度, 质量浓度

CLC Number:

P429

SUN Qunge, BAI Wei, BI Jianrong, WANG Xiting, ZHANG Yiyao, MENG Zhaozhao, WEI Gang, YIN Junzhi, WU Shangjiang. Study on the particle size distribution of summer dust aerosols in Jiayuguan gobi region, Gansu Province[J]. Journal of Arid Meteorology, 2026, 44(2): 293-302.

孙群阁, 白玮, 闭建荣, 王茜婷, 张圯尧, 孟钊钊, 魏刚, 尹俊植, 武尚将. 甘肃嘉峪关戈壁区夏季沙尘气溶胶粒径谱分析[J]. 干旱气象, 2026, 44(2): 293-302.

Figures/Tables 8

Fig.1 Time series of 5 min-averaged mass concentration （a）， number concentration （b）， mass concentration proportion （c）， and number concentration proportion （d） of aerosol in different particle size segments from August 1 to 31， 2024

Fig.2 Diurnal variations of average mass concentrations of dust aerosol and pollutants in August 2024

Tab.1 The proportion of aerosol number concentration and mass concentration across five particle size segments under different weather types

粒径段/μm	晴天		浮尘		扬沙		沙尘暴
粒径段/μm	数浓度	质量浓度	数浓度	质量浓度	数浓度	质量浓度	数浓度	质量浓度
0.5~1.0	80.9	3.2	70.5	2.2	63.7	2.0	39.9	0.5
>1.0~2.5	15.4	15.0	24.2	17.3	30.8	19.2	48.3	14.7
>2.5~5.0	3.2	28.7	4.7	28.0	4.8	25.5	9.8	23.1
>5.0~10.0	0.4	24.5	0.5	23.8	0.6	24.7	1.7	30.2
>10.0~20.0	0.1	28.6	0.1	28.7	0.1	28.6	0.3	31.5

Fig.3 Diurnal variations of average mass concentration （a） and number concentration （b） of aerosols under different weather types in August 2024 （Dust storm events correspond to the right Y-axis）

Fig.4 Average particle size distributions in the range of 0.5-20.0 μm of aerosol number concentration （a） and mass concentration （b） under different weather types in August 2024 （Dust storm events correspond to the right Y-axis）

Fig.5 Temporal variations of aerosol number concentration （a） and mass concentration （b） for different particle sizes from August 8 to 10， 2024

Fig.6 Six-hour averaged variations of aerosol number concentration spectra （a， c， e） and mass concentration spectra （b， d， f） before （a， b）， during （c， d） and after （e， f） the dust storm event

Fig.7 HYSPLIT （Hybrid Single-Particle Lagrangian Integrated Trajectory） model analysis at the observation station during the dust storm event from 09：00 August 6 to 09：00 August 9， 2024

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