北京近255年雨季及其多年变化

THE RAINY SEASON AND ITS VARIATION IN BEIJING DURING THE LAST 255 YEARS

中文摘要:

      本文利用1724-1903年北京故宫“晴雨录”中雨日记载,与现代气象资料衔接,确定了北京1724-1978年共255年雨季的起迄,并且讨论了雨季特征及其长期演变规律.北京雨季可划分为六种类型:提前型、落后型、偏长型、偏短型、双峰型、假雨季和副雨季.北京雨季平均开始于6月25-29日,结束于8月9-13日,雨季乎均长50天.雨季起始期具有4.5年周期:雨季结束期具有4年左右和85年左右周期;雨季长度具有85年和170年左右周期.此外,北京255年雨季变化存在明显的由短变长的长期趋势.近30年来北京雨季处于近255年来异常偏长阶段.

英文摘要:

      In this paper,the rain and clear sky observations in Beijing by the Royal Observatory of the Ching Dynasty were used and combined with instrumental records to reconstruct rainy season from 1724 to 1978.Its characteristics and variations were discussed and concluded as follows:1.There were 6 patterns of rainy season in Beijing during the last 255 years,and each of them prevailed in a certain period of time.2.The begining date of rainy season in Beijing in the average was in the 3rd.decade of June,ranging from the early part of May and 3rd.decade if August.The ending date of it in the average was in 2nd.decade of August ranging from the last part of June to 3rd.decade of Sept.The average length of rainy season was 50 days,ranging from 10 to 115 bays.The number of rainy day in the rainy season was 32(average),ranging from 9 to 82 days.