19世纪中叶北京高分辨率沙尘天气记录:《翁心存日记》初步研究

High-resolved sand dust records of Beijing in the middle of 19th century:A preliminary study of Weng Xincun Diary

《翁心存日记》是迄今为止发现的记录天气现象最为详细的历史天气日记,保留了难得的19世纪中叶北京的沙尘天气记录。归纳了对历史文献记录中的沙尘天气进行分类的方法,通过《翁心存日记》,重建了19世纪中叶北京沙尘天气情况。分析发现当时北京年平均沙尘日多达31.36天,高于近60年来北京沙尘天气的平均水平。而19世纪中叶的北京沙尘天气中扬沙、浮尘和沙尘暴天气的构成和现代基本相似,年内分布特征也较相似。但19世纪中叶夏季沙尘比例较现代明显偏多46%,而冬季沙尘比例仅为现代比例的75%,这说明古今间沙尘天气的季节分布可能存在较大差异。另外,19世纪的沙尘天气同样存在明显的年际变化,且本地降水是影响年际变化的因素之一。

Weng Xincun Diary conveys the most detailed weather records among all the known histori cal diaries, which provides valuable contemporary reports of dust weather in the middle of 19th century in Beijing. Firstly, this paper extracts every sand dust record scattered in this diary. By analyzing the sand dust records statistically, this paper reconstructs the sand dust weather condition in Beijing in the middle of 19th century. What＇s more, the detailed dust records provide the possibility to recognize the subdivi sion of the sand dust weather in historical time, the sandstorm, sand blowing and the floating dust weath er. As the present research has no official classification methods to classify the dust weather from historicalrecords, this paper explores a way to classify the different types of sand dust weather. The results show that ： （ 1 ） the annual average sand dust days of Beijing at that time is up to 31.36 times, which is higher than the annual average sand dust days during the last 60 years. （2） The classification of different types of sand dust weather shows that the composition of sandstorm, sand blowing and floating dust weather is similar to that of today, the inner annual distribution of sand weather days in the middle of 19th century also shares similarity to today＇s data. （3） The main difference lies in the season distribution of sand weather： In the 1850s, the sand weather occurrence in summer is higher than today by 46%, the sand weather occurrence in winter however, is lower by 15% compared with the present status. This result may show that the seasonally distribution of sand dust weather changes greatly from ancient time. （4） The in terannual variability of sand weather is quite obvious in the 1850s, and this paper shows that the local pre cipitation acts as an important role in the annual variability of sand dust weather.