Two mega sand and dust storm events over northern China in March 2021: transport processes, historical ranking and meteorological drivers

Abstract

Abstract. Although a remarkable reduction in the frequency of sand and dust storms (SDSs) in the past several decades has been reported over northern China (NC), two unexpected mega SDSs occurred on March 15–20, 2021 and March 27–29, 2021 (abbreviated as the “3.15” and “3.27” SDS events), which has reawakened widespread concern. This study characterizes the origins, transport processes, magnitudes of impact, and meteorological causes of these two SDS events using a long-term (2000–2021) dust optical depth (DOD) dataset retrieved from MODIS measurements and a comprehensive set of multiple satellite and ground-based observations combined with atmospheric reanalysis data. During the 3.15/3.27 event, the invasion of dust plumes greatly degraded the air quality over large areas of NC, reaching extremely hazardous levels, with the maximum daily mean PM10 concentration of 7058 µg m−3 (2670 µg m−3) recorded on March 15 (28). CALIOP observations show that during the 3.15 event the dust plume was lifted to an altitude of 4–8 km, and its range of impact extended from the dust source to the eastern coast of China. In contrast, the lifting height of the dust plume during the 3.27 event was lower than that during 3.15 event, which was also confirmed by ground-based Lidar observations. The MODIS-retrieved DOD data registered these two massive SDS events as the most intense episode in the same period in history over the past two decades. These two extreme SDS events were associated with both atmospheric circulation extremes and local meteorological anomalies that favored enhanced dust emissions in the Gobi Desert (GD) across southern Mongolia and NC. Meteorological analysis revealed that both SDS events were triggered by an exceptionally strong Mongolian cyclone generated at nearly the same location (along the central and eastern plateau of Inner Mongolia) in conjunction with a surface-level cold high-pressure system at the rear, albeit with differences in magnitude and spatial extent of impact. In the GD, the early melting of spring snow caused by near-surface temperature anomalies over dust source regions, together with negative soil moisture anomalies induced by decreased precipitation, formed drier and barer soil surfaces, which allowed for increased emissions of dust into the atmosphere by strongly enhanced surface winds generated by the Mongolian cyclone.

Measuring PM2.5 Concentrations from a Single Smartphone Photograph

“…However, this spatial heterogeneity was inconspicuous at 7:00 am. These disparities across space and time revealed that the dust transport process was strongly associated with the meteorological factor (mainly driven by north-westerly winds) and had a high magnitude, which is in accordance with the results of previous studies [40]. Moreover, on 29 March (average estimated PM 2.5 was 23.673 µg/m 3 ) (Figure 6c,d), a limited heterogeneity was observed, suggesting relatively homogeneous air quality patterns.…”

Compound events and associated impacts in China

“…Some hydroclimatic events with large impacts during recent decades in China can also be viewed as compound events, such as sand storms and saltwater intrusions. The severe sand storm in spring 2021 sweeping across northern China ( Gui et al., 2021 ) is a case in point. Sand storms are affected by both surface conditions (e.g., vegetation coverage and soil moisture) and meteorological factors (e.g., wind field and large-scale pressure fields) ( Xu et al., 2020 ).…”

Simulation of a Severe Sand and Dust Storm Event in March 2021 in Northern China: Dust Emission Schemes Comparison and the Role of Gusty Wind

“…Lack of precipitation, excessive snowmelt, and strong evaporation resulted in dry soil. The loose and dry soil in Mongolia provided favorable conditions in dust sources [26,27]. The atmospheric river (Figure 2b) from the South China Sea to Northeast China may enhance the intensity of the Mongolian cyclone by providing more water vapor for latent heat release [39,40].…”

“…Northern China experienced another SDS event on 27-29 March. This SDS event was much weaker than the SDS event on 14 to 15 March, with lower peak PM 10 concentrations [25,27]. In order to investigate the reliability of the gusty-wind model with the LS scheme, the same model configurations were used to simulate the SDS event on 27-29 March.…”

“…Northern China experienced a severe SDS in March 2021, leading to excessive particulate pollution and strong wind [25][26][27]. Yin et al [26] analyzed the climatological causes of this SDS event.…”