Spatio-temporal variations of precipitation in Beijing
CHENG Bingfen
HU Xiaozheng
ZHANG Rui
ZHU Quanjie
ZHENG Guiqiang
Abstract：Based on the time series data of precipitation in Beijing from 1978 to 2020,the temporal and spatial variations of precipitation in Beijing were systematically revealed by applying the Mann Kendall trend analysis,empirical orthogonal function and wavelet analysis methods.Firstly,during 1978-2020,the annual precipitati-on in Beijing exhibited a slowly decreasing trend that was not statistically significant.However,a significant in-creasing trend was observed from 1997 to 2020(slope=7.72 mm/year,α=0.05).Concurrently,the number of rainy days showed a significant decreasing trend over the entire study period(slope=0.3 days/year,α=0.05).Abrupt changes primarily occurred around 1996 and during 2010-2018.The 1996 transition point showed strong correlation with the East Asian Summer Monsoon Index,while multiple transition points post-2010 in the annual precipitation series may be associated with enhanced climate variability in recent years.Secondly,the intra-annual distribution of precipitation from 2004 to 2020 was extremely uneven,mostly concentrated in June-September,with the highest intra-annual shares of rainfall and rainy days reaching 89.2%and 67.1%,respectively.The precipitation and rainy days showed the characteristics that decrease se-quentially in summer,autumn,spring,and winter.Thirdly,the annual precipitation in Beijing decreased from east to west,primarily influenced by the geographical distribution of topography.Empirical orthogonal function(EOF)analysis revealed that the city's precipitation distribution was characterized by either predominantly rainy or less rainy conditions as the first main mode,accounting for 94.8%of the variance.In recent years,there was an increasing trend in precipitation amount in the northeast region and a decreasing trend in the southwest region.Finally,the precipitation in Beijing had significant periodicity on the time scale of about 10 years,23 years and 36 years,and the periodic distribution characteristics of dry and wet precipitation was obvi-ous.Due to multiple factors such as precipitation stations and observation sequences,there is a certain degree of uncertainty in the research results.
Keywords：precipitationrainy daystime seriesspatial variability
Publication Date：2025-08-30
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：10( 109-118 )