Recent Progresses in Studies of Regional Temperature Changes in China
Recent Progresses in Studies of Regional Temperature Changes in China
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发表时间：
2005
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通讯作者：
R. Guo
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作者：
R. Guo
本文对近年来中国气温变化的一些主要研究成果作了简要的总结。这些结果主要来自于对近55年、100年和1000年地面气温和近50年自由大气温度观测变化的研究，对地面气温变化的人为影响的研究，以及快速城市化对站点气温记录和区域平均气温序列的影响。利用国家基本站和基准站资料，经过质量控制和校正，建立了近55年和100年的地面气温时间序列。新的温度序列总体上比以前的温度序列变暖更快，年平均温度的变化率达到0.22 ℃/10a。近55年和100年的平均气温分别为0.08 ℃/10 a。目前的增暖在东北、华北、西北和青藏高原较为显著，且最大的升温出现在冬春季。近55年来的变暖是平均最低气温明显上升的结果。全国年平均极端低温也发生了同样的变化，而年极端高温只经历了一个微不足道的上升。与温度相关的极端事件如寒潮、凉夏、高温日数的发生频率在全国范围内总体上呈减少或不变的趋势。然而，它被发现，城市化的显着影响记录的温度趋势，单站以及区域平均温度序列存在于少数地区的调查到目前为止。华北地区是我国气候变暖最显著的地区，1961-2000年，城市化引起的国家基本站和基准站年平均气温升高达0.44 ℃，增温率为0.11 ℃/10a，占国家基本站和基准站记录的总增温率的38%。城市化对其他区域年平均气温变化的影响可能还存在。尽管地表显著变暖，对流层中低层（850-400 hPa）温度变化不大，变化率仅为0.05 ℃/10 a，对流层上层平流层低层（100 - 50 hPa）和300 - 150 hPa的温度分别以-0.17 ℃/10 a和-0.22 ℃/10 a的速率显著下降。在整个对流层的温度略有下降，发现在调查期间。而对流层中低层温度在近20年来的上升速度明显高于以往，地表温度与对流层中低层温度变化的差异逐渐减小。以西部的树木年轮资料和东部的历史资料为基础，初步重建了近1000年的气温序列。它显示了与中世纪温暖期（MWP）相对应的温暖时期，以及从1400年到1900年持续的小冰河时期的显着寒冷。然而，MWP的温暖似乎并不像以前报道的那样在全国范围内如此明显，尽管世纪末和世纪中期的温度可能高于20世纪的任何一个十年。现在要回答是什么导致了中国地表的变暖还为时过早。有证据表明，这主要是由于大气中温室气体浓度的增加，但目前还不能排除其他因素的影响，如太阳活动和海洋-大气系统的低频振荡。
A brief summary of some recent major research findings of temperature changes over China is made in this paper. The findings come mainly from studies on observed changes of surface air temperature of the last 55 years, 100 years and 1 000 years, and of free atmospheric temperature of the last 50 years, on attribution of surface air temperature change to anthropogenic forcing, and on effect of rapid urbanization on site temperature records and regional average temperature series. Based on a data set of national basic and reference stations, which have been quality-controlled and adjusted for in-homogeneity dominantly induced by relocation of stations, updated surface air temperature time series of the past 55 years and 100 years are established. The new temperature series show a generally more rapid warming than those obtained before, with the rates of change of annual mean temperature reaching 0.22 ℃/10 a. and 0.08 ℃/10 a respectively for the past 55 year and 100 years. The current warming is more significant in Northeast China, North China, Northwest China and the Tibetan Plateau, and the largest increase in temperature occurs in wintertime and springtime. The warming of the last 55 years is the result of more obvious rising of mean minimum temperature. The same change has happened for the country averaged annual extreme low temperature, while the annual extreme high temperature only experiences an insignificant rise. The frequency of temperature-related extreme events such as cold wave, cool summer, hot days generally tends to decrease or to be unchanged in the country as a whole. It is found, however, that significant effects of urbanization on recorded trends of temperature for single stations as well as for region averaged temperature series exist in a few regions investigated so far. In North China which experiences the most remarkable warming in the country, increase of annual mean temperature induced by urbanization for national basic and reference stations reaches 0.44 ℃ in period of 1961—2000, with an increasing rate of temperature of 0.11 ℃/10 a, accounting for 38% of the total warming rate as recorded by these stations. The effects of urbanization might have remained in the other regional changes in annual mean temperature. Regardless the remarkable warming of the surface, mid-to lower troposphere (850—400 hPa) witnesses no significant change in temperature, with a rate of change of only 0.05 ℃/10 a for the period of 1961—2004, and upper troposphere (300—150 hPa) and lower stratosphere (100—50 hPa) are experiencing a significant decrease in temperature at rates of -0.17 ℃/10a and -0.22 ℃/10 a respectively. A slight decrease in temperature is found for the entire troposphere in the period investigated. However, mid-to lower troposphere temperature is increasing in the past 20 years at a much higher rate than before, and the difference of change between surfaces and mid-to lower troposphere is getting smaller. A preliminary temperature series of the past 1 000 years has been reconstructed mainly based on tree ring data in the west and historical record in the east. It shows the warmth of period corresponding to the Medieval Warm Period (MWP) and the marked coldness of the Little Ice Age last from about 1400 to 1900. The warmth of the MWP, however, seems not so evident in the country as a whole as reported before, though the temperature in the end of 11th century and in the mid 13th century might have been higher than that of any decade of 20th century. It is still premature to answer the question of what cause the observed warming on the surface in China. Some evidence support the claim that it has mainly been induced by the increased concentration of greenhouse gases in atmosphere, but the influences of other factors like solar activities and the low-frequency oscillations of ocean-atmospheric system could not be ruled out at present.