近500年我国东部冬季气温的重建

RECONSTRUCTION OF WINTER TEMPERATURE IN EAST CHINA DURING THE LAST 500 YEARS USING HISTORICAL DOCUMENTS

本文利用近500年(1470—1979)我国东部(25°N—35°N,115°E—120°E)冬季河湖结冰和大雪、冰冻以及有关寒冷灾害记载,重建了这一时期的气温序列。首先将这些记载按照其反映气候寒冷的程度分别分为3级,然后根据他们各自与冬季气温的关系按不同权重加以组合,并导出一个冬季寒冷指数。最后利用近百年实测资料建立了该指数与相应10年平均气温距平的关系,从而得到了自1470年以来我国冬季气温的10年平均距平序列。结果表明,相对于近30年(1951—1980年)平均气温而言,过去500年总的来讲是偏冷的,其中包括3个主要冷期。30年滑动平均距平在-1.0℃以下的分别为1490—1519,1630—1699和1830—1889年,其中最冷的1840—1869年比近30年平均低约1.5℃,16世纪中后期和整个18世纪相对较为暖和,但仍比近30年平均低0.3—0.4℃,本世纪20至40年代为最暖期,其次为1520—1549年,前者比近30年高0.3—0.4℃,后者高0.2—0.3℃。

Winter temperature series of last 500 years in East China (25-35°N,115-120°E) was reconstructed using historical data about freezing of rivers and lakes, severe snowing and the relevant damages to agriculture caused by cold weather in the region. First, series of freeze-up and that of snowing were produced separately on a basis of ordinal scale. Then combination of the two series with different weights was made according to their relationship to winter temperature established by recent observations, and a cold winter index (Icw) was derived thereby. Finally, the winter temperature series was constructed at a resolution of 10 years on the basis of calibration of regression between the rece nt observation at Shanghai from 1873 to 1980 and the relevant Icw constructed. It is concluded that winter temperatures in the last 500 years are generally lower than the recent 30 year (1951-1980) mean. Three cold periods were detected, including periods of 1490-1519, 1639-1690 and 1830-1889, where the 30 year running mean temperature reched below -1.0℃, the coldest period lasting from 1840 to 1869, with temperature lower that the recent 30 year mean by about 1.5℃. The late 16th and the whole 18th centuries are relative warm, however the temperatures of these periods are still lower than the recent years by 0.3-0.4℃. The warmest period of the lay 500 years lies in the early part of the present century from 20's to 40's, with temperature higher than recent 30 year mean by about 0.3-0.4℃, another warm period ranged from 1520 to 1549, with temperature higher than that of the recent years by about 0.2-0.3℃.