Variation characteristics of extreme precipitation indicators in central Yunnan Province from 1960 to 2020

Abstract

[Objective] Extreme precipitation is an important fact that lead to flood-waterlogging disaster and has an important impact on agricultural production.To explore the spatiotemporal evolution law of extreme precipitation indicators in the central area of Yunnan Province.[Methods] Based on the daily precipitation date at 44 stations from 1960 to 2020, the variation trends and period characteristics of extreme precipitation indices in central Yunnan Province is nalyzed.[Results] The result showed: Over the past 60 years, maximum 1-day precipitation(Rx1day), maximum 5-day precipitation(Rx5day), simple daily intensity index(SDII), ≥10 mm precipitation days(R10), days ≥20 mm precipitation days(R20), maximum consecutive wet days(CWD), very wet day precipitation(R95p), and Extremely wet day precipitation(R99p) exhibit an initial increasing trend followed by a subsequent decreasing trend. Conversely, maximum consecutive dry days(CDD) demonstrates an initial decreasing trend before transitioning into an increasing trend. Rx1day, SDII and R99phad a significant increasing trend, while CDD, Rx5day, R10, R20, R95p and Total precipitation amount(PRCPTOT) showed no significant change trend, and CWD had a significant decreasing trend. The high values of Rx1day, Rx5day, R10, R20, R95p, R99p and PRCPTOT are located in the northwest, northeast and southeast of the central Yunnan region, and the low values are located in the west-central Yunnan region. The high value of SDII is located in the northwest of the central Yunnan region, and the low value is located in the central western part of the central Yunnan region. The CDD exhibited a gradient of decrease from the northwest to the southeast. The high value of CWD is located in the northwest, southeast and central part of the central Yunnan region, and the low value is located in the west-central part of the central Yunnan region. Wavelet analysis shows that Rx1day, Rx5day, R10, R20, SDI, CDD, CWD, R95p, R99p and PRCPTOT all have periodicity within 8a.[Conclusion] Mann Kendall trend analysis can play an important role in analyzing the time series trends and mutation points of precipitation elements; The slope estimation of Sen plays a crucial role in trend analysis of long-term precipitation data; Continuous wavelet analysis can infer the periodic changes in precipitation elements, which has great value for promotion and application. By studying the spatiotemporal evolution of extreme precipitation indicators in central Yunnan, reference can be provided for irrigation and drainage planning, disaster prevention and reduction in the region.

Keywords

extreme precipitation indices / Mann-Kendall trend analysis / Sen slope estimation / continuous wavelet analysis / central Yunnan Province / climate change / spatiotemporal distribution / rainfall