中文摘要：

流域水文平衡不仅决定于降水和潜在蒸散发总量,而且还受到其年内季节性变化特征的影响。收集1956—2010年中国743个国家级气象站逐日气候资料,采用FAO-Penman公式计算潜在蒸散发量,插值计算10 km网格日降水和潜在蒸发,进行水热季节性特征的变化分析。结果表明,82.8%的区域潜在蒸散发量均值有下降趋势,但减少量不大,同时其年内季节性特征没有显著变化。表征降水年内波动振幅的季节性指数在全国范围均有显著下降趋势,且北方流域更为明显,变化率最大的西北诸河达到6.4%/10 a;峰值时间和雨季长度则变化不显著。这种水热季节性的变化被认为会导致流域径流的减少,在今后中国径流变化的归因研究中,应该考虑降水季节性变化的贡献。

英文摘要：

The hydrological partitioning is not only governed by the relative magnitude of precipitation and potential evapotranspiration （PET） , but also by their seasonal distribution. Based on the daily observations from 743 national meteorological stations during 1956 to 2010, the FAO-Penman equation was employed to calculate daily PET. To construct the seasonality indices, the interpolated 10-km grid daily precipitation and PET were analyzed. The results indicate that the daily PET shows an overall decreasing trend over 82. 8% of the China, while the decreasing rate is not large. And the other seasonal indices of PET also have no significant trend. As for precipitation, the seasonality index has a significant decreasing trend across the China with a largest rate of 6.4% per 10 years in northwestern regions and the decreasing trend is more severe in northern basins. The centroid and duration of precipitation regime have not shown obvious changing pattern. The changes in precipitation and PET seasonality can lead to decreasing runoff, which should be noted in the future research on the attribution of change in runoff.