Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-05-30 Cooperative journals: 《干旱区研究》
Abstract： To quantitatively evaluate the effect of meteorological conditions on air pollution, data from 14 meteorological sounding stations and surface observation stations in Xinjiang were used to analyze the spatial and temporal distribution characteristics of atmospheric self-purification capacity index (ASI) and air stagnation index (ASITS) from 2010 to 2020. Results showed a negative correlation between ASI and ASITS. ASI was the largest in summer and the smallest in winter. It was generally greater in southern Xinjiang than in northern Xinjiang, whereas ASITS showed the opposite trend. This implied that the atmospheric diffusion conditions were better in southern Xinjiang than in northern Xinjiang, and a static and stable atmospheric circulation more easily formed in northern Xinjiang than in southern Xinjiang. The daily pollution data of air environment monitoring stations from 2015 to 2020 were used to determine the correlation between the air quality of Xinjiang in different seasons and the air quality of five heavily polluted stations and the two indexes. The two indexes highly correlated with the air pollution data of Urumqi station, and the static stability index was better, which can well indicate the degree of air pollution. However, no good correlation was found between the two indexes and the air pollution data of four stations in the southern Xinjiang basin. In the heavy pollution case in the spring of 2018, the PM10 concentration span was very large, so the two indexes showed a high dispersion on the scatter diagram, which is not applicable. In particular, in Hotan and Aksu, the two indexes showed a certain correlation with the pollutant concentration, and ASITS performed better. In Kashgar, ASI showed no correlation with air quality, and ASITS showed a weak correlation; the two indexes showed no correlation with the air quality of Korla, implying poor applicability. Further study on the distribution of indexes under different pollution levels in the capital city of Urumqi showed that the early warning indicators can be preliminarily condensed as follows: When pollutant emission is serious, and if ASI is distributed at 0-20 t·(d·km2)−1, it is susceptible to heavy weather pollution, and the range of ASITS is of little significance.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2021-12-14 Cooperative journals: 《干旱区地理》
Abstract： 利用逐时地面气象数据、探空秒级数据及风廓线雷达数据分析了 2013—2017 年乌鲁木齐 低空焚风演变时边界层和近地层气象扩散条件的变化特征。结果表明：（1）乌鲁木齐大气扩散条 件总体呈现夏季最有利，冬季最差（最大混合层厚度 0.44×103 m、通风系数 1.52×103 m2•s-1、逆温层 厚度 768 m、逆温层温差 4.82 ℃、静稳指数 6.36），且冬季 12 月与 1 月极不利于污染物扩散。（2）冬季 低空焚风演变的 5 个阶段，大气混合层厚度、通风系数呈减小—增大特征，焚风强盛期混合层厚度 最低（0.30×103 m）、通风系数最小（0.62×103 m2 •s-1）；逆温层厚度及强度、静稳指数变化趋势为增 大—减小特征，强盛期逆温最强（10.9 ℃）、逆温层厚度（0.99×103 m）、静稳指数最大（9.7）。（3）低空焚风过程的发展期和强盛期各站气压减小，高海拔站点气温升高、风速增大，焚风层以下低海拔区 域气温降低、风速减小，说明焚风使得焚风层以下区域的大气更加稳定，不利于污染物扩散。（4）总体上焚风致使水平扩散能力和垂直交换能力减弱，大气易凝结，结束后扩散条件重建。业务中可利用焚风发展趋势预判边界层扩散条件及地面气象要素的演变，为乌鲁木齐城市群空气污染预报 和污染治理提供参考依据。
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