内蒙古阿拉善地区沙尘天气与部分气候因素关系研究

Relationship between Climatic Factors and Sand-Dust Weather Events in the Alxa Region of Inner Mongolia

利用24个气象站点（1961年～2005年）44年的气象数据记录，运用多元线性回归和ArcGIS空间分析方法，定量分析了部分气候因子与浮尘、扬尘、沙尘暴天气发生及变化规律的关系，同时结合阿拉善地区的植被（类型）覆盖图，分析了沙尘天气的分布特点、变化规律及其成因。结果显示，阿拉善地区是我国沙尘天气的多发地区之一，浮尘平均发生日数的空间分布规律是自西北向东南递增；扬尘的空间分布规律是东北部较多，其余地区较少；沙尘暴的空间分布规律是以拐子湖地区为中心向西北、西南、东南3个方向递减，这种分布特点与阿拉善地区的植被覆盖有关。在1961年～2005年的时间段，3种沙尘天气的变化规律各有特点，浮尘天气日数呈先升后降的变化特点，90年代以后发生的日数明显下降；扬尘天气呈波动变化状态；沙尘暴天气亦呈逐渐减少的变化趋势。沙尘天气的发生日数与当时的温度状况呈显著负相关，而与大风日数呈显著正相关，其中与年大风日数的相关关系更为明显，年大风日数每增加10天，浮尘天气一般增加3～6天，扬沙天气一般增加4～10天，而沙尘暴天气一般增加1～3天。当大风日数相同时，沙尘天气发生日数与地袁覆盖状况（下垫面性质）有关。由于本区常年降水稀少，降雨量与沙尘天气发生之间的关系未见明显。

This paper analyzes the trends of occurrence and spatial distribution of sand-dust weather events （floating dust, blowing sand and sand-dust storms） in the Alxa region of Inner Mongolia. We use multiple linear regression and spatial analysis techniques in ArcGIS to examine the relationship between spatiotemporal trends of sand-dust events and climatic factors such as strong wind, temperature, and rainfall. Data was obtained from 24 meteorological stations in the region, covering the period from 1961 to 2005. The spatial distribution pattern of sand-dust weather events as affected by land cover features was also analyzed by combining the climatic data with a vegetation cover map of the Alxa region. The results show that this region experiences a high concentration of sand-dust events. Throughout the region, there is a general pattern of increase in the annual mean of days with floating dust from northwest to southeast, with a higher average of days with blowing sand in the northeast compared to other parts, and more sand-dust storm events occurring per year in the Guaizi Lake and its surrounding area, with a radiating pattern of decrease in storm events from this zone to the outer northwest, southwest and southeast areas. This pattern of sand-dust event frequency is significantly related to regional vegetation cover characteristics. Temporal changes in the three types of sand-dust weather events from 1961 to 2005 are very different： the annual total of floating dust days increased steadily during the last century, and then decreased when nearing the year 2000. The annual number of days with blowing sand events fluctuated during the study period, and the annual number of days with sand-dust storms decreased gradually. There are significant correlations between the annual occurrence of sand-dust events and both annual mean temperature and gale wind frequency. The correlation in the former case is negative, while the latter relationship is positively correlated, with a more significant coefficient. These correlations suggest that the number of days with floating dust, blowing dust and sand-dust storm events increase by 3 - 6 days, 4 - 6 days and 1 - 3 days, respectively, with each increase of 10 days with gale winds. Under the same conditions of gale frequency but in different areas, the probability of sand-dust event occurrence will be different, as it depends greatly on surface vegetation cover. Due to the scarcity of annual precipitation throughout the region, we found no significant statistical relationship between the occurrence of sand-dust weather events and regional precipitation.