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Sand and dust storms (SDSs) are particularly concerning natural disasters in East Asia. At present, there is still a lack of comprehensive knowledge of the characteristics of the cross-border SDSs between Mongolia and Northern China and the associated weather systems. This study identifies and documents the spring cross-border SDSs between Mongolia and Northern China based on the MODIS AOD map and Himawari-8/9 dust RGB images and analyzes the corresponding weather system types. A total of 76 spring cross-border SDSs were identified during 2000–2023, accounting for 55.1% of the total SDSs in both countries. The vast majority of the cross-border SDSs (86.8%) were related to Mongolian cyclones (MCs). Among them, 53.9% of the cross-border SDSs were mainly driven by Mongolian cyclones alone, and 32.9% were driven by the combination of MCs and cold highs (MC-CH type). Significant differences in the horizontal distribution of the SDSs were observed for different weather types. MCs alone trigger SDSs in the southern halves of the MCs, so the horizontal extent of the SDSs is consistent with that of MCs but larger than that associated with cold fronts. For the MC-CH type, strong winds in the southern flanks of MCs and their rear cold highs jointly drive a large-scale zonally extensive SDS belt. In recent years, particularly in 2021 and 2023, the strong cross-border SDSs have been dominated by the MC–CH type. This study provides a reference for the forecasting and early identification of cross-border SDS disasters. [ABSTRACT FROM AUTHOR]

Rainstorms always occur in the southeast and northeast quadrants of the Northeast China Cold Vortex (NCCV), resulting in significant flooding. This study investigated water vapor and trigger mechanisms for rainstorms within these two regions of an NCCV event during 11–14 June 2022 in terms of Lagrangian backward tracking, stratification stability, and upward motion using the ERA5 reanalysis. In the mid-troposphere, a quasi-stationary "ridge-NCCV-ridge" pattern resided over northeastern China, with an "anticyclonic-cyclonic-anticyclonic" airflow in the lower troposphere. As a result, water vapor originated from the Yellow Sea and was transported in an "L" shape toward both two regions. The southeast region was influenced by southwesterly and northwesterly airflows, resulting in the convergence of moist air from the Yangtze River and Lake Baikal and significant vertical shear of positive vorticity advection. This dynamic created deep and pronounced upward currents in the southeast of the NCCV, leading to the development of intensive and extensive rainstorms in situ. In contrast, the northeast region of the NCCV was dominated by southerly airflow. The moist air converged against the lee side of the Great Khingan Mountains and generated shallow, unstable stratification. The upward motion in this area was relatively weaker and thus induced regional rainstorms. [ABSTRACT FROM AUTHOR]

Dust storms are common in Mongolia and northern China, this is a serious threat to the ecological security and socioeconomic development of both countries and the surrounding areas. However, a complete quantitative study of the source area, affected area, and moving path of dust storm events (DSEs) in Mongolia and China is still lacking. In this study, we monitored and analyzed the spatiotemporal characteristics of the source area and affected areas of DSEs in Mongolia and China using the high-spatiotemporal-resolution images taken by the Himawari-8 satellite from March to June 2016–2020. In addition, we calculated the moving path of dusty weather using the HYSPLIT model. The results show that (1) temporality, a total of 605 DSEs occurred in the study area, with most of them occurring in April (232 DSEs), followed by May (173 DSEs). Spatially, the dust storm sources were concentrated in the arid inland areas such as the Taklimakan Desert (TK, 138 DSEs) and Badain Jaran Desert (BJ, 87 DSEs) in the western, and the Mongolian Gobi Desert (GD, 69 DSEs) in the central parts of the study area. (2) From the affected areas of the DSEs, about 60% of the DSEs in Mongolia started locally and then affected downwind China, as approximately 55% of the DSEs in the Inner Mongolia Desert Steppe and Hunshandake Sandy Land came from Mongolia. However, the DSEs in the TK located in the Tarim Basin of northwest China affected the entire study area, with only 31.3% belonging to the local dust. (3) From the moving path of the dusty weather, the dusty weather at the three meteorological stations (Dalanzadgad, Erlian, and Beijing), all located on the main transmission path of DSEs, was mainly transported from the windward area in the northwest, accounting for about 65.5% of the total path. This study provides a reliable scientific basis for disaster prevention and control, and has practical significance for protecting and improving human settlements. [ABSTRACT FROM AUTHOR]

In this study, the northern Asian summer onset (NASO) is investigated in terms of its key features, thermodynamic driving factors, and its associations with the rainfall pattern in eastern China on the basis of the U.S. National Centers for Environmental Prediction and the U.S. National Center for Atmospheric Research reanalysis data, the snow cover extent data archived by the National Oceanic and Atmospheric Administration's National Centers for Environmental Information, and the precipitation data of observational stations in China. We define the NASO as the critical time when seasonal surface warming in northern Asia accelerates prior to this time and then stabilizes after this time. The climatological NASO occurs in the second pentad of June, across which systematic changes occur in the near surface warming in northern Asia. The heat budget analysis demonstrates from the climatic perspective that the snowmelt process in northern Asia plays a crucial role in the NASO. The positive feedback between surface warming and snowmelt facilitates an intense surface warming associated with the NASO. It is revealed that large‐scale wave patterns in the sea‐level pressure field contribute to early and late advents of NASOs. In association with the wave patterns, the horizontal linear advection term and adiabatic term are the primary thermodynamic drivers to the early and late NASOs. From late May to early July, the circulation anomalies from northern Asia to the subtropical western Pacific are significantly different between the early and late NASO years. Accordingly, in the rainy period, the seasonal evolution of rainfall pattern in eastern China also shows a considerable difference in these two NASO years. [ABSTRACT FROM AUTHOR]

A deep and cold vortex circulation often occurs over northeast China. Known as the northeast China cold vortex (NCCV), the phenomenon is most active from May to mid-June and can lead to extremely cold local temperatures. This study used rotated principle component analysis to categorize NCCV events into four types, which were characterized by ridges (or blocks) over the following regions: Lake Baikal (BKL), the Yenisei River valley (YNS), the Ural Mountains (UR), and the Yakutsk-Okhotsk region (YO). On the intraseasonal time scale, it was found that BKL- and YNS-type NCCVs formed when the wave train height anomalies originating from the North Atlantic and Europe propagated to East Asia. In contrast, YO- and UR-type NCCVs formed in conjunction with the development of a meridional dipole pattern over northeast Asia. The existence of a blocking-type circulation over the Yakutsk-Okhotsk region favored maintenance of the NCCV circulation for the long-lived (more than 5 days) NCCV events of the four types. The typical circulation over northeast Asia for the long-lived NCCV event was closely associated with wave breaking, whereas the short-lived (3-5 days) event showed only wave propagation. The YNS-type NCCV caused cold surface air temperatures (SAT) not only over northeast China, but also over central and south China, whereas the other three types led only to regional cold SAT anomalies over northeast China. All four types of NCCVs caused a precipitation increase over northeast China, and this effect was broader for the UR- and YO-type NCCVs than that for BKL- and YNS-type NCCVs. [ABSTRACT FROM AUTHOR]

This study objectively defined an extreme precipitation event (EPE) over southern China and investigated the associated typical circulation pattern on the intraseasonal time scale. The occurrence of the EPE resulted from the joint operations of anomalous circulations over the subtropics and mid-high latitudes. During the EPE, simultaneous enhancements of the trough over the Bay of Bengal (BBT) and the Western Pacific subtropical high (WPSH) facilitated the abundant water vapor conditions over southern China, whereas the weakened East Asian major trough (EAT) led to a moderate cold air invasion to that region, producing a persistent convergence zone over southern China. Wave train pattern in North Atlantic and Europe may be viewed as precursory signals for the EPE over southern China, and it contributed to the Rossby wave propagation in association with the EPE. These wave packets propagated toward East Asia mainly along the North African-Asian subtropical westerly jet waveguide. Low-frequency disturbances along this waveguide contributed to the enhancement of the BBT and WPSH and the weakening of the EAT, constituting favorable circulation conditions for the EPE. [ABSTRACT FROM AUTHOR]