摘要
According to the precipitation sequence of Beijing City from 1900 to 1958,the precipitation sequence of Chengde City were revised and extended.Then the precipitation sequence of Chaoyang City were revised and extended with the precipitation sequence of Chengde City to form 100-years precipitation sequence of Chaoyang.The results showed that the 100-years precipitation sequence of Chaoyang indicated a decreasing trend and obvious periodic variation with the change of age.That is,a 10-year rainy period (approximately 525.0 mm) appeared every 30 a,while the 30-year drought period was approximately 460.0 mm,65.0 mm lower than the former.Moreover,an obviously heavy drought lasting for 2-4 a appeared every 20 a.
According to the precipitation sequence of Beijing City from 1900 to 1958,the precipitation sequence of Chengde City were revised and extended.Then the precipitation sequence of Chaoyang City were revised and extended with the precipitation sequence of Chengde City to form 100-years precipitation sequence of Chaoyang.The results showed that the 100-years precipitation sequence of Chaoyang indicated a decreasing trend and obvious periodic variation with the change of age.That is,a 10-year rainy period (approximately 525.0 mm) appeared every 30 a,while the 30-year drought period was approximately 460.0 mm,65.0 mm lower than the former.Moreover,an obviously heavy drought lasting for 2-4 a appeared every 20 a.
