风速加强可能是近年中国沙尘日数增加的主要因素

Wind speed enhancement as the primary cause of sand-dust days increase in China over recent years

沙尘天气是中国北方干旱和半干旱地区的重要天气现象,也是影响该地区的主要灾害性天气之一[1,2].沙尘事件对环境、公共健康甚至全球气候都会产生重大影响,了解沙尘天气的驱动因素对制定有效的策略以减轻其影响至关重要[3~5].沙尘天气直接受到风速和沙源影响,而沙源又进一步受植被、降水、气温等因素影响[6~8].通过分析这些因素导致的沙尘天气频率变化过程,有助于我们预测未来的沙尘天气变化趋势.截至2023年4月30日,我国已经出现12次沙尘天气过程,比往年同期偏多.

Dust weather,a prevalent disaster in the arid and semi-arid areas of northern China,poses significant risks to both socioeconomic stability and public health.This meteorological phenomenon,characterized by strong winds sweeping sand particles across vast distances,frequently occurs in these regions.It inflicts considerable damage to infrastructure and environment,while also exposing human populations to an array of respiratory issues and diseases.However,despite the wide range of detrimental effects,the mechanics and influencing factors behind dust weather events remain laden with uncertainties.This lack of clear understanding impairs our ability to implement efficient prevention and control strategies,thereby necessitating in-depth exploration and research into the subject matter.Our quest to unravel the inherent dynamics of dust weather events led us to employ a multivariate analysis approach,combining ground meteorological observation data,satellite remote sensing data,and reanalysis data.Ground meteorological data,collected from weather stations scattered across the affected regions,provides accurate and precise measurements of local conditions such as wind speed,precipitation,temperature,and humidity.On the other hand,satellite remote sensing data opens up a bird’s eye view of the situation,enabling us to monitor vast areas simultaneously.Furthermore,it can also reveal changes in land cover and vegetation,providing insights into the potential natural barriers to dust movement.Reanalysis data is a climate or weather model simulation of the past that includes data assimilation.This type of data combines model data with observational data to provide a consistent long-term view of the weather.This unique dataset,spanning a broad time series from 1973 to 2023—Affords us the opportunity to precisely track the shifting characteristics of dust events,thereby laying the groundwork for the identification of potential correlations.Our research primarily seeks to comprehend the relationship between dust events and a selection of environmental parameters.We specifically zeroed in on three factors:Wind speed,precipitation,and vegetation.The selection of these variables is predicated on their considerable influence over atmospheric conditions and soil stability,both of which directly impact the magnitude and frequency of dust events.A salient conclusion from our study asserts that wind speed plays a pivotal role in the occurrence of dust events.There exists a substantial positive correlation between the annual average number of dust days and wind speed,with a correlation coefficient of 0.89 and a significance level of less than 0.01.This underscores that an uptick in wind speed parallels an increase in dust days.Data accumulated since 2013 reveal an upward trend in wind speeds,thereby leading to a surge in dust days.It suggests that if wind speeds continue their upward trajectory,northern China may experience more frequent and severe dust events.Our second conclusion proposes a relatively weak and arguably insignificant correlation between the number of dust days and both precipitation and vegetation indices.Yet,it is critical to note that these factors should not be entirely dismissed.Precipitation and vegetation cover potentially play a moderating role in the transportation process of dust particles.Rainfall can enhance soil stability,reducing the potential for sand particle dispersion,while vegetation establishes a natural windbreak,helping to curb the spread of dust particles.Lastly,we noted an overall upward trend in the springtime vegetation cover of northern China over the last 20 years.This indicates progress in China’s afforestation and desertification control efforts.Nonetheless,given the cross-border distribution of sand sources,solutions relying solely on one country’s actions may fall short of fully addressing the dust issue.Therefore,we underscore the urgent need for heightened international collaboration and coordination to tackle such cross-border environmental and ecological challenges.Pursuing sustainable development mandates our collective effort to combat the trials posed by dust events.In framing these solutions,we must account for a broader geopolitical context,encouraging global unity to mitigate the adverse impacts of dust events.