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CLIMATE IN CHINA DURING THE LITTLE ICE AGE

Wang Shaowu; Ye Jinlin; Gong Daoyi(Department of Geophysics, Peking University, Beijing 100871)  
Usually, 1550-1850, while the climate was relatively cold, was called as theLittle Ice Age. 30-year mean temperature in the coddle latitude of the NorthernHemisphere during the Little Ice Age was generally 1.0℃ lower than the observed inthe coddle and late present century. Lowering of temperature increased to 1.5- 2.0℃in the higher latitudes in the Southern Hemisphere.Zhu had indicated in 1973 that cold winters in China were concentrated in threePeriods; 1470-1520, 1620-1720, and 1840-1890, though he did not use theterminology of the Little Ice Age.Wang had reconstructed in 1990 decadal mean seasonal temperature anomalies ofNorth and East China for the period of 1470's to 1980' s. It provided at the firstbine an opportunity to examine the Little Ice Age in China based on a homogeneoustemperature series. Wang et al. (1990) then identifled three cold periods, which hadbeen denoted as Ⅰ, Ⅱ, and Ⅲ. Moreover, two colder stages were found in each ofthe cold periods, which were indicated as foot note 1 or 2. The cold stages in Chinawere as follows: 1,-1450' s- 1470' s, Ⅰ 2-1490' s-1510' s, Ⅱ1-1560' s-1600' s,Ⅱ2-1620' s- 1690' s,Ⅲ1-1790' s- 1810's and Ⅲ2-1830' s-1890' s.Recently, annual temperature series of 1880-1996 were constructed for each often regions of China. which covered whole territory of China, including Tibet andTaiwan. It provided good bases for reconstruction of tempeatre series for the last500 to 1000 years. In the following, data sources used in reconstruction were outlinedfrom region to region.(1) Northeast. Tree-ring data was used to reconstruct annual temperature between1748 to 1880 (Wei Sonlin personal communication). New tree-ring data of ShaoXuemei was used for the period 1600 to 1748.(2) North. Decadal mean temperature anomaly series were used, which werereconstructed by Wang on the basis of documentary data.(3) East The same as used for North.(4) South. Decadal mean temperature anomaly series were reconstructed recentlyby using of the same method as for the North and East China.(5) Taiwan. The same as for South.(6) Central-South. Decadal mean temperature series were reconstructed by YeYuyuan et al. (Personal commnication ) on the basis of documentary data.(7) Southwest. The same as used for South.(8) Northwest. Ice core δ18O data in Dunde were used.(9) Xinjiang. Ice core δ18O data in Guliya were used.(10) Tibet. Tree-ring data of Kang Xingcheng were used.Decadal means of temperature are used in present study, for the limit of theresolution of proxy data. Firstly, all kinds of the proxy dare are normalized, and thenthe regional standard deviation of decadal mean temperature is multiplied, which wascalculated by using of observatory data of 1961-1990. It insures the homogeneity ofthe series. Finally, regional decadal-mean temperature anomaly series are obtained.However, the length of the series varies from region to region. The longest seriesavailable now are that for Xinjiang, Northwest and Tibet. Historical documents allowtO reconstruct the series only since 1380 to 1470, for the scarce of dare in early time.However, thes is the first bine one can examine the Little Ice Age in the wholeterritory of China.Main results are as following:(1) To establish the series of China, regional temperature anomalies are averagedwith the weighting factors, which are proportional to the size of the region.(2) All of the regional series positively correlate to the series of China.Maximum correlation coefficients are found between Northwest Tibet on the one handand National on the others.(3) Ten regions can be divided into three groups: 1) Mainland areal, includingNorth, Ease Northwest and Tibet. 2) South territory, including South, Central-Southand Southwest. 3) Surrounding area including Xinjiang and Northeast.(4) Five cold periods are identified for the last millennium; 1100's- 1150' s, 1300' s- 1390' s, 1450' s- 1510' s, 1560' s- 1690's and 1790' s- 1890' s.However, temperature anomaly varied from region to region in each of the coldperiods. The first two periods can be regarded as a transition to the L
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