Impact of COVID-19 Lockdown and Atmospheric Circulation on the Air Quality in Wuhan During Early 2020

Xie, Youyong; Zhi, Xiefei

doi:10.1051/e3sconf/202129902011

Cited by 1 publication

(1 citation statement)

References 10 publications

(20 reference statements)

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“…N means that the region is controlled by a northerly geostrophic flow; the rotational flow is divided into two categories, which can either be cyclonic (C) or anticyclonic (A); the mixed type would include A-hybrid types (AN, ANE, AE, ASE, AS, ASW, AW, ANW) and C-hybrid types (CN, CNE, CE, CSE, CS, CSW, CW, CNW). CN means that the area is controlled by a low-pressure system under the influence of northerly winds, and so on [24,29].…”

Section: Ud (Undefined)mentioning

confidence: 99%

Classification of the Circulation Patterns Related to Strong Dust Weather in China Using a Combination of the Lamb–Jenkinson and k-Means Clustering Methods

Wang

Chen

et al. 2021

Atmosphere

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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.

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Section: Ud (Undefined)mentioning

confidence: 99%