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In the early summer (June) of 2022, the spatial mean precipitation in northeast China (NEC) was 62% higher than normal and broke the historical record since 1951. Based on the precipitation data of 245 meteorological stations in NEC and the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis, this paper analyzes the role of large-scale circulation and sea-surface temperature (SST) associated with anomalous precipitation over NEC in June using singular value decomposition (SVD), correlation analysis, regression analysis, and composite analysis methods, and further investigates the possible cause of the abnormal precipitation in June 2022. Results show that the northeast China cold vortex (NCCV) accompanying the blocking high in the Okhotsk Sea (BHOS) has been the primary mid-to-high latitude atmospheric circulation pattern affecting NEC precipitation in June since 2001. This circulation pattern is closely related to the tripole SST pattern over the North Atlantic (NAT) in March. In June 2022, the NAT SST anomaly in March stimulates eastward-propagating wave energy, resulting in the downstream anomalous circulation pattern in which the NCCV cooperates with the BHOS in the mid-high latitudes of East Asia. Under this background atmospheric circulation favorable for precipitation, the Kuroshio region SST anomaly in June led to a more northward and stronger anomalous anticyclone in the northwestern Pacific through local air–sea interaction, which provides more sufficient water vapor for NEC, resulting in unprecedented precipitation in June 2022. [ABSTRACT FROM AUTHOR]

Based on the precipitation records of 2474 meteorological stations, this study investigated precipitation characteristics and trends in China from 1961 to 2010, including spatiotemporal distribution and changes in average annual precipitation amount, number of days when daily precipitation > = 1, 5, 10, 25, 50 mm, and extreme precipitation indices. The results showed that: (1) in terms of annual average precipitation amount, both dry to wet, wet to wetter, and shifting between wet and dry showed decadal and climatical fluctuations in annual precipitation totals in space and time, with a clear shift in space from the 0 to 200 mm and above 400 mm precipitation levels to the 200 to 400 mm precipitation level. (2) In terms of graded precipitation days, three kinds of trend changes were observed: (a) enhancement, manifested as an increase in precipitation events, mainly in the northwest and northeast of China; (b) reduction, manifested as a decrease in precipitation events, mainly in the central parts of China; and (c) polarization, which is manifested as a decrease in gentle and light precipitation events but an increase in dry days, heavy, and rainstorm precipitation events, primarily along coastal area in southeast China. (3) In terms of extreme precipitation events, precipitation persistence showed a decreasing trend, but an increasing trend in precipitation intensity and magnitude in most regions of China. This paper also presents the relationship between certain atmospheric circulation indices and the seasonal precipitation of summer and winter. The distribution characteristics and changes in minor precipitation events were highlighted, including gentle and light rain events. Relevant findings can provide scientific guidance for water resource management and conservation. [ABSTRACT FROM AUTHOR]

Sand / dust occurrences are one of major disasters in arid and semi-arid areas. Understanding its time evolution as well as the impact factors is crucial for policy makers to protect human from health and economic losses. In this paper, we investigate the features of spring sand/dust frequency during 1961–2016 based on 201 surface meteorological stations in northern China, which are divided into four regions as Xinjiang, Northwest China, North China, and Northeast China according to the spatial distribution of sand/dust frequency. Although the regional mean sand/dust frequency exhibits a general declining trend in the last 56 years, it shows fluctuations with the maximum occurrence in the 1970s and the minimum in the 2010s, and abrupt changes can be found in the late 1980s by the Lepage test. We choose 1961–1988 as the active sand/dust period and 1989–2016 as the inactive sand/dust period. Apparent differences are found between these two epochs in the large-scale atmospheric circulations. The geopotential height over Mongolia and Inner Mongolia of China at mid-and lower troposphere became much higher, and the Asian polar vortex weakened and shrank noticeably in the inactive sand/dust period. For 1961–1988, a meridional dipole pattern of significant correlation in heights at mid-and lower levels was dominant over the northeastern Eurasian continent, while for 1989–2016, sand/dust frequency seems to have much closer relationship with local circulation and a zonal dipole structure at lower troposphere dominated over China. The relationship between the 850 hPa vorticity over Mongolia and sand/dust frequency was strengthened after the late 1980s for the western areas, but that was weakened for the eastern areas of northern China. Besides, the intensity of Asian polar vortex at 500 hPa had higher correlation with sand/dust frequency during 1989–2016 particularly for Northwest China. All these findings are important to refine reliable models for short-term climate prediction of sand/dust occurrence in East Asia. • Spring dust frequency decreased generally during 1961–2016 over northern China. • Significant abrupt changes of dust frequency occurred in the late 1980s. • Atmospheric circulation and its relationship with dust frequency differed between 1961 and 1988 and 1989–2016. [ABSTRACT FROM AUTHOR]