2000—2023年浑善达克沙地春季沙尘天气分布特征及其与植被盖度、风况的关系

Spring sand-dust weather distribution in Hunshandak Sandy Land in relation to vegetation and wind in 2000-2023

利用长时间序列的遥感观测、地面气象观测和空气质量监测数据,分析京津风沙源治理工程实施以来浑善达克沙地下垫面改善情况及春季沙尘天气特征。结果表明:与2000—2009年相比,2010—2022年浑善达克沙地约22%以上的区域植被覆盖度显著增加。浑善达克沙地的沙尘天气主要出现在偏西风影响下,表现出先减少后增加的趋势。2000—2006年为沙尘多发期,2007—2014年沙尘日数减少,2015—2023年沙尘日数再次增多,沙尘日数的变化趋势与6级及以上大风次数的变化趋势一致。大风次数的减少叠加起沙频率的下降,使得6级及以上大风影响下的起沙次数占总起沙次数的比例由21世纪初的接近80%下降至近年来的30%~40%,出现在较低风速条件下的沙尘天气明显增多。2012—2023年,境外传输对浑善达克沙地沙尘天气的影响日益显著。与本地起沙相比,境外传输的沙尘天气影响范围更大。

By using long-time series remote sensing observations,surface meteorological observations,and air quality monitoring data,the underlying surface improvement of Hunshandak Sandy Land and the characteristics of spring sand-dust weather since the implementation of the Beijing-Tianjin Sand Source Control Program were analyzed.The results showed that compared with the years 2000 to 2009,the vegetation coverage significantly increased in over 22%of the Hunshandak Sandy Land from 2010 to 2022.The sand-dust weather in the Hunshandak Sandy Land mainly occurred under the influence of westerly winds,showing a trend of first decreasing and then increasing..The period from 2000 to 2006 was a period of frequent occurrence of sand-dust weather.From 2007 to 2014,the number of sand-dust days decreased,and the number of sand-dust days increased again from 2015 to 2023.The trend of the sand-dust days was consistent with the trend of strong winds above level 6.The decrease in the number of strong winds combined with the decrease in the frequency of sand formation had led to a significant decrease in the proportion of sand formation times under the influence of strong winds above level 6,from nearly 80%at the beginning of this century to around 30%-40%in recent years.As a result,the sand-dust weather under lower wind speeds had seen a significant increase.From 2012 to 2023,the impact of sand-dust weather from overseas was becoming increasingly significant in the Hunshandak Sandy Land.Compared to local sand-dust weather,the impact range of sand-dust weather from overseas was larger.