Spatial And Temporal Variation Characteristics Of Extreme Precipitation In The West Of Fujian

Basing on 30-years’ daily precipitation data of Fujian from 1980 to 2009 in the western region, and adopting the statistical principle, earth spatial interpolation method, Mann-Kendall mutation analysis and complex Morlet wavelet cycle analysis, this paper mainly studied the average precipitation, temporal and spatial distribution characteristics of precipitation in different order of magnitude, extreme precipitation threshold, all types of extreme precipitation events as well as the spatial and temporal distribution of extreme precipitation index of the west Fujian province. In addition, it also studied the fact of total annual precipitation, precipitation and extreme precipitation mutation characteristics and cycle laws in western Fujian. The results show that:(1) In west Fujian area, the western part overall has more rainfall than the eastern region. Light rain days account for the major rainy days. Moderate rain and heavy rain make the biggest contribution to the total rainfall. Slight rain, light rain, moderate rain, heavy rain all showed downward trend, especially the moderate rain and heavy rain falling the most. Rainstorm and heavy rainstorm are on the rise, and heavy rainstorm rises more obviously. (2) The threshold of extreme precipitation is in the range of heavy rain precipitation. The gap among average extreme precipitation days in different area is small, but in different years is opposite. It is high likelihood that drought and flood will appear alternately. High and low occurrence rate of the three types extreme precipitation events distribute interlaced, and less overlap. Extreme precipitation distribution is more uniform in the whole area. Extreme precipitation event happens in spring, summer, autumn three seasons and presents a growing trend. Summer is given priority to the other two seasons. Dain level of each kind of average intensity of extreme precipitation approximates the rainstorm precipitation. (3) There are significant correlations among the annual average precipitation and CWD, RIO, R95pTOT, SDII, RXlday, RX5day. Average extreme precipitation and total annual rainfall also show significant correlation. Extreme precipitation presents significant correlation with rainstorm and heavy rainstorm. (4) The average annual precipitation amount from 1980 to 2009 presents upward trend. Slight rain, light rain, moderate rain, heavy rain precipitation are characterized by declining trend, but the rainstorm and heavy rainstorm are characterized by significant rising trend. In the western Fujian intensity of extreme precipitation events has the increasing trend. (5) The main cycle of the annual extreme precipitation and annual average rainfall of western Fujian is 5a. Stability of extreme precipitation is better than that of annual precipitation. And they present the same change direction.