喀什地区浮尘天气特征及一次重污染天气成因分析

根据1961—2018年喀什地区9个国家站浮尘日数逐日观测资料,利用气候学统计、M-K突变检验等方法分析喀什地区浮尘日数的时空分布等气候特征,分析2019年3月19—25日喀什地区出现的强浮尘造成的重污染天气成因。结果表明:喀什地区年平均浮尘日数为71 d,浮尘日数总体呈减少趋势,并于1997年前后发生了显著减少性突变。2019年3月19—25日出现的强浮尘天气过程,持续时间长,影响范围广,乌拉尔山高压脊发展,脊前横槽转竖,在新疆东部回流东灌冷空气是造成此次沙尘过程的天气背景。浮尘天气造成21—24日喀什地区空气污染指数AQI指达500,属严重污染,首要污染物PM_(2.5)和PM_(10)在21日、22日达到峰值,分别为494、1 175μg/m~3。热力、动力条件以及近地面存在逆温层均不利于污染物的扩散。污染过程前后喀什市本站气压与PM_(10)、PM_(2.5)浓度均呈正相关,相关系数为0.762、0.507,均通过0.05显著性水平检验;气温与PM_(10)浓度呈负相关,与PM_(2.5)相关性不明显;相对湿度跟PM10和PM2.5呈正相关,表明气象因子在大气污染过程中对大气环境影响明显。

Analysis on the characteristics of floating dust weather and the causes of one heavy pollution weather in kashgar

Based on the daily observation data of floating dust in 9 countries in kashgar from 1961 to 2018,using climate statistical, M - K mutation test methods such as analysis of kashgar region dust days of time and space distribution, the climate characteristics of floating dust weather climate background understanding of kashgar region, and on March 19 ~ 25, 2019, the emergence of strong dust weather are analyzed. The results show that the annual average number of dust days in kashgar is 71 days, and the number of dust days in kashgar shows a decreasing trend. Significant reductive mutations occurred around 1997. The strong dust weather occurred from March 19 to 25, 2009, which lasted for a long time and affected a wide range. The development of the Ural high-pressure ridge and the cross low-troughturn to vertical, the cold air flowing back to the east of Xinjiang is the weather background causing the dust weather. The air pollution index (AQI) of kashgar was up to 500 on the 21st to 24th, which was considered as serious pollution. The primary pollutants PM2.5 and PM10 peaked on the 21st and 22nd, at 494 g/m3 and 1175 g/m3 respectively. Thermal and dynamic conditions, as well as the existence of inversion layer near the ground, are not conducive to the diffusion of pollutants. Before and after the pollution process, the air pressure of kashgar city was positively correlated with the concentration of PM10 and PM2.5, with the correlation coefficient of 0.762 and 0.507, both of which passed the significance test of 0.05. The temperature was negatively correlated with PM10 concentration, but not significantly correlated with PM2.5. Relative humidity is positively correlated with PM10 and PM2.5, indicating that meteorological factors have a significant impact on the atmospheric environment in the process of air pollution.