中国北方过去2000年沙尘事件与气候变化*

文章依据冰芯、树木年轮等自然记录和历史文献记录,分析了中国北方不同地区近2000年的沙尘事件及其与气候变化的关系。结果表明,在干旱区西部,历史时期的沙尘变化主要受温度变化的制约,无论在10年尺度,还是百年尺度上,沙尘事件与温度变化均表现为显著的反相关,即气候寒冷期与沙尘频发事件相对应,气候温暖期与沙尘发生变弱期一致;在半干旱区,在10年尺度上温度和降水序列与沙尘发生频率均显著负相关,但在百年尺度上沙尘与降水变化的关系更为密切;在干旱区东部,沙尘与气候变化的关系具有明显的过渡性特征,气候变化对沙尘事件的作用主要在百年尺度上体现出来,沙尘与温度记录的负相关比降水更好,在10年尺度上气候与沙尘序列尽管也是负相关,但不显著。通过对现代气象记录的气温、降水变化和沙尘事件频数分析,其结果与历史时期情况基本一致。

DUST STORM EVENTS AND THEIR RELATION TO CLIMATE CHANGES IN NORTHERN CHINA DURING THE PAST 2000 YEARS

According to the "Climate Regionalization Map of China" compiled by China Meteorological Administration in 1978, and fuzzy cluster zoning by Xu, et al., we divided the research area into three sub-areas, the western arid region, the eastern arid region, and the semiarid region. Dust storm events and their relation to climate changes in North China during the past 2000 years were analyzed by using paleoclimate proxies, such as ice cores, tree rings, and historical documents. Dust storm events over the last 2000 years reflected by Ca²⁺ and Mg²⁺ contents recorded in the Guliya ice-core and microparticle concentration in the Dunde ice-core as well as dust storm events recorded in historical documents of China are compared with ice accumulation rates, δ¹⁸ O, tree-ring width, and multi-proxy reconstructed temperature and precipitation sequences. We tried to quantify the contribution of temperature and precipitation to dust storm occurrences in different regions, to probe into the dust storm formation mechanism and develop a model of climate changes and dust storm events.The results show that in the western arid region at both the decade timescale and the century timescale, the dust storm changes were mainly controlled by temperature changes during the past 2000 years and the dust storm events and temperature changes exhibite a significant negative correlation. In other words, the dust storm events were more frequent under cold climate than under warm climate. In the semiarid region, temperature and precipitation sequences were both significantly negatively correlated to dust storm at decade timescale. At century timescale however, precipitation changes have a closer correlation with dust storm events than temperature. In the eastern arid region, the relationship between dust storm events and climate changes displayed obvious transitional features, and the effects of climate changes on dust storm events were mainly manifested at century timescale. The negative correlation between temperature and dust storms was more obvious than that of precipitation and dust storms. On the other hand, although the climate and the dust storm sequences were also negatively correlation at decadal timescale, such negative correlation was not significant. Analysis of modern meteorological records over the last 50 years came to the roughly same conclusion.