近60年河西走廊地区沙尘暴发生演变特征及其气象影响因子

Evolution Characteristics of Sandstorm and Meteorological Influence Factors in Hexi Corridor in Recent 60 Years

为探讨沙尘暴演变特点及影响因素,应用河西走廊13个气象站1960—2019年的逐日沙尘暴和同期130项大气环流特征量资料,采用概率统计、线性倾向率、滑动t检验等方法,详细分析了河西走廊沙尘暴频次的时空演变特征、沙尘暴持续时间和强度特点及变化规律,并使用相关系数(Pearson)法进一步探索沙尘暴的气候影响因素。结果表明:沙尘暴频次呈显著减少趋势,年际倾向率为3.2 d/10 a,且这种减少趋势存在突变;四季沙尘暴均为减少趋势,减少速度为春季>夏季>冬季>秋季;空间演变特点为,沙尘暴发生频次与减少速度呈显著正相关,减少速度为民勤最快,马鬃山最慢。沙尘暴平均持续时间为119 min,持续60~300 min的频次最多,>300 min的频次最少;持续时间呈显著缩短趋势,年际倾向率为-7.42 m/10 a,近9年持续时间缩短最明显。沙尘暴过程平均最小能见度为0.569 km,最小能见度为0.5~1.0 km的一般沙尘暴频次最多,<0.05 km的特强沙尘暴频次最少;近16年沙尘暴强度无明显变化。沙尘暴频次和持续时间与副高西伸脊点指数呈显著正相关,与西太平洋副高面积指数、西太平洋副高强度指数、东亚槽强度指数、西藏高原-1指数、西藏高原-2指数、大西洋多年代际振荡指数呈显著负相关。由此可见,大气环流指数是影响沙尘暴发生发展的重要因素之一。

In order to study the evolutionary characteristics and influencing factors of sand-dust storm, the methods of probability statistics, linear tendency rate and sliding t test were used, the spatial and temporal evolution characteristics of sandstorm in Hexi Corrido and its changing regularity were analyzed in detail based on the daily sandstorm data from 13 weather stations from 1960 to 2019 and the atmospheric circulation characteristics provided by the National Climate Center, and the climatic influencing factors of sandstorms were explored by correlation coefficient method. The results showed that the sandstorm had a significant decreasing trend, the interannual trend rate was 3.2 d/decade, and the decreasing trend was mutational, the reduction gradient of sandstorm decrease in the order: spring>summer>winter>autumn. The spatial evolution characteristics was that occurrence frequency of sandstorm was positively correlated with the decreasing level, which was the highest in Minqin and the lowest in Mazong Mountain. The average duration of sandstorm was 119 minutes, the duration frequency of 60~300 minutes was the most, the duration frequency of>300 minutes was the least. The duration showed a significant shortening trend, the interannual trend rate was-7.42 m/decade, the most obvious shortening had been observed in the last 9 years. The average minimum visibility of sandstorm was 0.569 km, the average frequency of general sandstorm with the minimum visibility of 0.5~1.0 km was the most, and the frequency of <0.05 km super-strong sandstorm was the least, the intensity of sandstorm had no obvious change in recent 16 years. The frequency and duration of sandstorms were positively correlated with the Western Pacific Sub Tropical High Western Ridge Point Index, and negatively correlated with the Western Pacific Subtropical High Area and Intensity Index, East Asian Trough Intensity Index, Tibet Plateau Region-1 and-2 Index, Atlantic multi-decadal Oscillation Index. The atmospheric circulation index is one of the important factors that affect the occurrence and development of sand-dust storms.