Dust activity in East Asia has shown multi-scale temporal variations in the past. Many studies have been devoted to the interannual variations of dust activity, but little attention is paid to its variations at the intra-seasonal scale and our knowledge on this is still limited. Several dust storms have occurred over East Asia in spring 2023, which is taken as a good example for us to explore the intra-seasonal variations of dust activity. Based on station observations of dust events, meteorology reanalysis, and satellite observations of surface vegetation cover, here we find that there is much difference in dust storm activity between March and April of 2023 in terms of both the location and intensity. Dust storms mainly occurred in the central and eastern parts of Inner Mongolia and in the central and northern parts of Tarim Basin in March. In contrast, they mainly occurred in the western part of Inner Mongolia, eastern part of Northwest China, and a large region of Tarim Basin. For the regional mean number of dust storm days (NDS), it is significantly higher than the climatological mean value of 2003–2022 in April but lower for March of 2023. Further analysis reveals that the frequency of strong wind is below (above) the climatological mean for March (April) in the Tarim Basin and Gobi Deserts, indicating that wind speed may play a key role in the intra-seasonal variations of dust storm activity, although its effect is offset or enhanced by that of soil moisture and vegetation cover to a lesser extent. The shift of wind field is closely related to the evolution of geopotential height from positive anomaly in March to negative anomaly in April in Mongolia Plateau and southern Central Siberia at 500 hPa. Overall these results highlight the intra-seasonal variation of dust activity in spring 2023 in East Asia and the essential role of associated atmospheric circulation in driving this.

中文翻译：

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2023 年春季东亚沙尘活动的季节内变化及其机制


东亚的尘埃活动在过去表现出多尺度的时间变化。许多研究都致力于沙尘活动的年际变化，但很少关注它在季节内尺度上的变化，我们对此的了解仍然有限。2023 年春季东亚地区发生了几场沙尘暴，这为我们探索沙尘活动的季节内变化提供了一个很好的例子。根据对沙尘事件的站观测、气象再分析和对地表植被覆盖的卫星观测，我们发现 2023 年 3 月至 4 月的沙尘暴活动在位置和强度方面存在很大差异。3月份，沙尘暴主要发生在内蒙古中东部和塔里木盆地中北部地区。而内蒙古地区西部地区、西北地区东部地区和塔里木盆地大片地区地区则主要发生。对于区域平均沙尘暴天数 （NDS），4 月明显高于 2003-2022 年的气候平均值，但低于 2023 年 3 月的气候平均值。进一步分析表明，塔里木盆地和戈壁沙漠强风的频率低于（高于）3 月 （4） 月的气候平均值，表明风速可能在沙尘暴活动的季节内变化中发挥关键作用，尽管其影响在较小程度上被土壤水分和植被覆盖所抵消或增强。500 hPa 时，蒙古高原和中西伯利亚南部的风场偏移与位势高度由 3 月的正距平演变为 4 月的负距平密切相关。 总体而言，这些结果突出了东亚 2023 年春季沙尘活动的季节内变化，以及相关大气环流在驱动这一变化中的重要作用。