Abstract
Sand and dust storms (SDSs) cause major disasters in northern China. They have serious impacts on human health, daily life, and industrial and agricultural production, in addition to threatening the regional ecological environment and social economy. Based on meteorological observational data and the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 dataset for spring 2000–2021, we used the Lamb–Jenkinson circulation classification method to classify the three major areas influencing SDSs in northern China. We also used the k-means clustering method to classify the overall circulation pattern in northern China. Our results show that the circulation types favoring SDSs in the southern basin of Xinjiang are southwesterly winds (SW), cyclones (C), and anticyclones (A). The circulation types favoring SDSs in western Inner Mongolia and southern Mongolia are northwesterly winds (NW), northerly winds (N), cyclones (C), and anticyclones (A). The circulation types favoring SDSs in central Inner Mongolia are northwesterly winds (NW), northerly winds (N), southwesterly winds (SW), and anticyclones (A). The 500 hPa and surface circulation patterns in China can be divided into nine types. Among them, five dominant circulation patterns favor strong SDSs: a cold high-pressure region and cold front (T1), a Mongolian cyclone (T2), a mixed type of Mongolian cyclone and cold front (T3), a thermal depression and cold front (T5), and a cold front (T8). During 2000–2004, the T8 circulation pattern occurred most frequently as the main influencing circulation. From 2005 to 2010, the T3 and T8 circulation patterns dominated. Circulation patterns T1 and T3 dominated during 2011–2015 and 2016–2020, respectively. We analyzed the main circulation patterns for four SDS events occurring in 2021 by combining the Lamb–Jenkinson and k-means methods. The SDS events in 2021 were closest to the T3 circulation pattern and were mainly influenced by Mongolian cyclones and surface cold fronts. The main propagation paths were westerly and northwesterly.
Highlights
Because the most SDS events in northern China occur in spring [27], this paper focuses on the upper air and surface circulation type classifications of SDS events
To better study the types of surface circulation when sandstorms occur, it is first necessary to understand the characteristics of the circulation patterns in northern China in the spring
The results show that the important circulation types in the southern Xinjiang basin are the C (25.23%), A (14.59%), W (12.07%), southwesterly winds (SW) (7.90%), and CW (6.38%) types, whereas in western Inner Mongolia and southern Mongolia they are the C (23.40%), A (7.90%), N
Summary
We used the dust storm thematic dataset (V1.0), a daily station observational dataset from the National Meteorological Information Center. This dataset includes the daily occurrences of floating dust, blowing sand, and dust storms at 2474 stations. Administration classifies sand and dust weather at a single station into five levels: floating dust, blowing sand, SDS, severe SDS, and extreme severe SDS [26]. A regional floating dust or blowing sand event refers to a weather process in which five or more adjacent stations record floating dust or blowing dust at the same observation time. For regional SDS, severe SDS, or extreme severe SDS events, the corresponding sand and dust weather is recorded in at least three adjacent stations at the same observation time. Because the most SDS events in northern China occur in spring [27], this paper focuses on the upper air and surface circulation type classifications of SDS events (regional SDS, regional severe SDS, and regional extreme severe SDS) in spring (March to May)
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