NOAA/WDS Paleoclimatology - Reconstruction of winter temperature in east China during the last 500 years using historical documents

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 construeted.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℃,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℃.