Spatial and Temporal Variation Characteristics of Extreme Precipitation Indexes in the Tarim Basin from 1961 to 2021
Based on the daily precipitation data from 39 meteorological stations in the Tarim Basin in China from 1961 to 2021 and 10 extreme precipitation indexes recommended by the World Meteorological Organization,the study investigate the variation characteristics of the indexes by using some statistical methods,including linear trend estimation,Mann-Kendall test,accumulative anomaly,sliding t-test,signal-to-noise ratio test and Morlet wavelet analysis.The results show that the heavy precipitation,extreme precipitation,maximum 1-day precipitation amount,maximum 5-day precipitation amount,moderate rain days,heavy rain days and consecutive wet days,all decrease from the northwestern mountainous areas to the central-eastern basin.The heavy precipitation days index is highly localized,and the extreme heavy preciptiation over 50 mm is mainly concentrated at the plain stations in the central-eastern parts of the basin.Over the past 61 years,extreme precipitation events in the Tarim Basin have shown an obvious"extreme"and"humidification"trend.The indexes such as heavy precipitation,extreme precipitation,precipitation intensity,maximum 1-day precipitation amount,moderate rain days,heavy rain days and consecutive dry days,have demonstrated different degrees of increase at most stations,while the consecutive wet days has shown a decreasing trend.There are some regional differences in the variation rate of extreme precipitation indexes,with a"fast in the west and slow in the east"pattern.The extreme precipitation indexes exhibit obvious interannual fluctuations and interdecadal oscillations.The interannual anomalies of each extreme precipitation indexes experience a"from less to more"variation from the 1980s to the 1990s(they are opposite in the consecutive dry period).After that,the oscillation has increased and shows a certain degree of unstability.In terms of mutation and periodic characteristics,the extreme precipitation events in the basin experienc an obvious turning point in the mid-1980s,with notable mutation observed in all indexes except for heavy precipitation days.During the middle-to-late 1980s,extreme precipitation indexes display distinct cyclical variations.Except for the 5-day maximum precipitation and the consecutive wet days,the other indexes show relatively stable quasi-3-year or quasi-6-year high-frequency oscillations.
Tarim Basinextreme precipitationspatial and temporal variationgeneral atmospheric circulation
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