Analysis of climate change of Meiyu precipitation in Hubei Province in recent 52 years

Based on daily precipitation data at 70 stations and data of the onset time, ending time, duration and intensity index of Meiyu in Hubei Province during 1961-2012, by using the least squares fitting, moving average and analysis of the trend coefficient and climate tendency rate, the time variation, spatial distribution, trend change and intensity index are analyzed for climate change of Meiyu precipitation in Hubei Province in recent 52 years. Results can be summarized as follows. (1) The onset time, ending time, duration of Meiyu are quite different during past years, and the latter is long but showed a decreasing trend. The year 2000 is a turning point, after which the onset time is delayed, ending time is in advance, duration is shorten, and Meiyu precipitation weakens. (2) Annual rainfall, rainfall amount, storm rainfall and numbers of station and time of Meiyu are large. The quotient of rainfall amount of Meiyu to annual rainfall and storm rainfall to rainfall amount of Meiyu are high. All of them are quite different during past years. Interannual variability of annual rainfall shows the small-amplitude fluctuations and shocks, others show greater fluctuations and shocks. Their trends are consistent except for the quotient of rainfall amount of Meiyu to annual rainfall. (3) Meiyu precipitation has obvious regional and decadal changes. The average characteristic during the 52 years shows that high values are in southwestern and eastern region of Hubei and low values are in northwest region of Hubei. Rainfall amount of Meiyu is, respectively, more and less, and the quotient of rainfall amount of Meiyu to annual rainfall is, respectively, higher and lower in the 1990s and 2000s than in other periods. Both of storm days and storm rainfall of Meiyu are less and the quotient of storm rainfall to rainfall amount of Meiyu is lower in the 1970s than in other periods. (4) Analysis of trend coefficient and climate tendency rate shows that the quotient of storm rainfall to rainfall amount of Meiyu in eastern region of Hubei significantly increases. Annual rainfall, the quotient of rainfall amount of Meiyu to annual rainfall, rainfall amount, storm days and storm rainfall of Meiyu at most stations have increased mainly in southern region of Jianghan Plain, southeastern region of Hubei. In a small part of stations they have decreased mainly in middle and northern region of Jianghan Plain, southwestern region of Hubei, although all of their trends are not clear. (5) Intensity index has a weakly increasing trend, which is strong in typical waterlogged years and weak in typical dry years. And weak index years are the most which are up to 20.