河西走廊东部沙尘日变化特征及其与气象因子的关系

沙尘天气是河西走廊东部多发的灾害天气之一.为提高河西走廊东部沙尘天气的预测、预报、预警水平，更好地预防沙尘灾害和沙尘天气对空气质量的污染.利用河西走廊东部5个气象站1960-2016年逐日沙尘（包括浮尘、扬沙及沙尘暴）资料和四季平均气温、最高气温、最低气温、平均风速、大风日、蒸发量、降水量、相对湿度等资料，运用统计学方法分析了河西走廊东部各强度沙尘日的时空分布特征以及沙尘日与气象因子的相关性.结果表明:受海拔、地形地貌以及天气系统等影响，各强度沙尘日（除浮尘外）由东北向西南呈递减趋势.年代、年各强度沙尘日呈显著减少趋势，沙尘暴、扬沙、浮尘递减率分别为-2.436、-5.277、-5.719 d/（10 a），气候趋势系数均通过了α=0.01的显著性水平检验.年沙尘日的时间序列均存在着6~8 a的准周期变化.各强度沙尘日均为春季最多，秋季最少，且各季节沙尘日均呈显著减少趋势，递减率为春季>夏季>冬季>秋季，气候趋势系数均通过了α=0.01的显著性水平检验.各强度沙尘日月变化比较一致，高峰值出现在4月，低谷值出现在9月.气象因子对沙尘天气有一定的影响，同一季节气象因子对各强度沙尘日的影响相对一致，但不同的季节气象因子对各强度沙尘日的影响不一致.热力因子和动力因子是影响沙尘天气的主导因子，水分因子的影响较弱.研究显示，气候变暖、冷空气活动频次和强度减弱是沙尘日减少的主要原因之一，大气环流的季节性转变是沙尘天气季节性变化的主要原因. 

Variation Characteristic of Sand-Dust Days and Its Relationship with Meteorological Factors in East of Hexi Corridor

Sand-dust weather is one of the most frequent disaster weather in the east of the Hexi Corridor area. In order to improve prediction, forecast and early warning level of sand-dust weather, and better prevent sand-dust disasters and pollution of sand-dust weather to air quality in the east of Hexi Corridor. Using daily sand-dust days including dust, flying sand and sandstorm and mean temperature in four seasons, the maximum temperature, the minimum temperature, wind speed, gale day, evaporation, precipitation and relative humidity data of five meteorological stations in the east of Hexi Corridor during 1960-2016, temporal and spatial distributions of sand-dust days and its relationship with meteorological factors were analyzed with using statistical method in the east of Hexi Corridor. The result showed that various intensity sand-dust days (except for floating dust) all assumes a significant decrease trend from the northeast to the southwest because of influence of altitude, landform and weather system. Various intensity sand-dust days of age and year all assumes a significant decrease trend, decline rates of dust storm, sand and dust are -2.436, -5.277 and -5.719 d/(10 a) respectively, and climatic trend coefficients pass the significant level test of α=0.01. Time series of various intensity sand-dust days have six to eight years quasi-periodic variations. Various intensity sand-dust days mostly occur in spring and the least in autumn, sand-dust days of various season all shows a significant decrease trend, and lapse rates are spring > summer > winter > autumn, and climatic trend coefficient passed the significant level test of α=0.01. Monthly variations of various intensity sand-dust days are relatively consistent, a peak is in April and a trough is in September. Meteorological factors have a certain influence on sand-dust weather. Influence of meteorological factors to each intensity sand-dust days are relatively consistent in the same season, influences of meteorological factors to each intensity sand-dust days are different in seasons Thermal and dynamic factors are dominant factors affecting sand-dust weather, and influence of water factors is weak. The climate warming and frequency and intensity of cold air weakening are one of main reasons for dust-dust days decreasing. Seasonal change of atmospheric circulation is main reason for seasonal change of sand-dust weather.