Spatial And Temporal Characteristics Of Summer Precipitation With Different Durations Over Central And Eastern China

Using the dataset of hourly rain gauge records at510stations covering the central and eastern China (east of100°E), the hourly based spatial and temporal characteristics of summer precipitation were discussed, in order to investigate the differences between the space-time distribution of rainfall.with different durations and its possible causes. Result shows that:1. Summer rainfall amount, intensity and frequency increase from northwest to southeast. Frequency decreases logarithmically as the intensity increases, while the moderate rainfall (1.1-10.0mm/h) take the largest contribution. The intensity is closely related to the duration of the rainfall events. With the duration increases, there are less small rainfall (0.1-1. Omm/h) and more moderate rainfall (1.1-10. Omm/h). Rainfall larger than10. Omm/h are evenly distributed across the rainfall event longer than1h, but the intensity of those in shorter events seems to be higher.2. Rainfall events persisting2h give the greatest contribution to summer precipitation. For the events longer than2h, the amount and the frequency decrease as the duration increases. The average rainfall event durations in different areas show significant differences, which is equal or less than6h in South China, North China and Northeast China, but larger than6h in central eastern China (30-35°N).For the events longer than6h, the position of maximum value moves to east as the duration increases.3. Considerable differences exist in terms of sub-seasonal and diurnal variation between the short duration events (1-6h) and the long duration events (>6h). The rainfall in the monsoon rain belt is dominated by the long duration events, when the short duration events mainly occur over South China and North China during the breaking period. Two peaks appear after midnight and late in the afternoon respectively, and long (short) duration events dominate the nocturnal (afternoon) precipitation. 4. During1961-2012, a prominent feature of the linear trend is the "southern flooding and northern drought". Both the intensity and the frequency increase in the southern China, while the decrease of rainfall at the northern China is mainly attributed to the change of frequency. The rainfall lager than10. Omm/h show more significant trend in the southern China, while "northern drought" can be partly ascribed to the decrease of rainfall lighter than10.0mm/h. The distribution of the95th extreme precipitation is similar to that of the rainfall larger than10.0mm/h.5. Event durations show positive trend at most regions of central and eastern China, particularly in the Yangtze-Huai river basin (YHR), leading to the expansion of the regional difference. Long and short duration events both have influence on the decadal variation of summer precipitation in central and eastern China. In South China, both long and short duration rainfall decrease in early1980’s and increase in early1990’s. The leading cause of the abrupt change in YHR during late1970’s is the change of rainfall longer than6h. In North China, the trend of long and short duration rainfall last decade is opposite.6. The East Asia summer monsoon index is significant negative correlated with the summer long duration precipitation over YHR. A shift to southwest of the subtropical high could cause a positive anomaly of long duration rainfall. The short duration rainfall over YHR is significant correlated with the accumulated rainfall over North China and show positive anomaly during La Nina. The Atlantic and North India SST also have influence on the rainfall over YHR.