19世纪后半叶至20世纪初叶梅雨带位置的初步推断

Location of Rainbelt of Meiyu During Second Half of 19th Century to Early 20th Century

提取《湘绮楼日记》中1869-1916年间长沙、衡阳地区夏半年（4-9月）的逐日天气记录,重建4-9月逐旬平均降水日数序列和6-7月逐候平均降水日数序列,与现代（1951-1980）长沙气象观测数据进行对比,发现当时梅雨期结束于7月3候,较现代推迟2候;梅雨持续时间2-3旬,比现代长约1旬。参考物候信息（历年平均蝉始鸣日期）得出结论：19世纪后半叶至20世纪初,冬季风势力强于现代,压制了副热带高压北进,当时梅雨带位置较现代偏南1-2个纬度。长衡地区因此较现代更接近梅雨带中心,出现了更明显的梅雨。

In this paper, an ancient diary named Xiangqilou Diary, which was written by Wang Kaiyun during 1869 -1916 in the area around Changsha and Hengyang in Hunan Province where he lived, has been dug out. By using of the daily weather recordation in the diary, a series of average precipitation days of every ten days in summer-half-year （Apr. - Sep. ） from 1869 to 1916 around Changsha and Hengyang, as well as series of precipitation days of every penta-day （5 days）during June to July, can be reconstructed. After comparing with meteorological observation data in Changsha （ 1951 - 1980）, it is found that the end of Meiyu period （ the third pentaday in July） was about two penta-days（ 10 days） later than present, and the length of Meiyu period （20 -30 days） was about ten days longer. According to phenological recordation on cicada in the diary, the average date when cicada first sang around Changsha and Hengyang was the 30th June. Compared to the modem phonological data, the date was later than Changsha and Hengyang, while similar to several cities along the Changjiang （ Yangtze） River, such as Shanghai, which are now in the core area of rainbelt of Meiyu in the eastern China. Consequently, climate during Meiyu period of the two has some similar characters, especially temperature and precipitation. In conclusion, during the second half of the 19th century to the early 20th century, Meiyu was more typical than present around Changsha and Hengyang, which means the area might be much liker to the core area of rainbelt of Meiyu, and the location of rainbelt of Meiyu then was about 1 ° - 2° south to nowadays.