任国玉, 柳艳菊, 孙秀宝, 张莉, 任玉玉, 徐影, 张华, 战云健, 王涛, 郭艳君, 陈峪, 唐国利, 郭军. 中国大陆降水时空变异规律——Ⅲ. 趋势变化原因[J]. 水科学进展, 2016, 27(3): 327-348. DOI: 10.14042/j.cnki.32.1309.2016.03.001
引用本文: 任国玉, 柳艳菊, 孙秀宝, 张莉, 任玉玉, 徐影, 张华, 战云健, 王涛, 郭艳君, 陈峪, 唐国利, 郭军. 中国大陆降水时空变异规律——Ⅲ. 趋势变化原因[J]. 水科学进展, 2016, 27(3): 327-348. DOI: 10.14042/j.cnki.32.1309.2016.03.001
REN Guoyu, LIU Yanju, SUN Xiubao, ZHANG Li, REN Yuyu, XU Ying, ZHANG Hua, ZHAN Yunjian, WANG Tao, GUO Yanjun, CHEN Yu, TANG Guoli, GUO Jun. Spatial and temporal patterns of precipitation variability over mainland China: Ⅲ: causes for recent trends[J]. Advances in Water Science, 2016, 27(3): 327-348. DOI: 10.14042/j.cnki.32.1309.2016.03.001
Citation: REN Guoyu, LIU Yanju, SUN Xiubao, ZHANG Li, REN Yuyu, XU Ying, ZHANG Hua, ZHAN Yunjian, WANG Tao, GUO Yanjun, CHEN Yu, TANG Guoli, GUO Jun. Spatial and temporal patterns of precipitation variability over mainland China: Ⅲ: causes for recent trends[J]. Advances in Water Science, 2016, 27(3): 327-348. DOI: 10.14042/j.cnki.32.1309.2016.03.001

中国大陆降水时空变异规律——Ⅲ. 趋势变化原因

Spatial and temporal patterns of precipitation variability over mainland China: Ⅲ: causes for recent trends

  • 摘要: 中国大陆现代降水表现出若干长期变化特征,对现代降水趋势性变化的原因,目前还没有很好了解。结合多种资料分析以及前人研究成果,对中国大陆近几十年降水变化趋势的原因进行了探讨,得到以下初步认识:① 现代降水量变化趋势具有明显的地域性差异,全国平均没有表现出显著增加或减少的长期变化,但强降水事件频率和降水量出现明显增多,而小雨事件特别是痕量降水事件显著减少。② 再分析资料表明,最近几十年全国水汽净收支量在一定程度上增加了,实际观测资料显示近地面和对流层中下层空气比湿或大气可降水量出现较明显上升趋势。③ 代用资料序列分析显示,全国大部地区近几十年降水变化仍处于晚近历史时期正常自然波动范围内;近百年观测的降水量序列也表明,黄淮海地区降水具有多重时间尺度相互叠加作用特点,低频自然气候变异的影响信号有清晰表现。④ 人类活动引起的大气中温室气体浓度增加对全国或东部季风区现代降水变化影响的信号,目前仍难以识别;区域性近地面风速减弱导致的雨量观测系统偏差以及大范围气溶胶浓度增加,可能是东部季风区大多数台站观测到的强降水事件频率增加和小雨频率显著减少的两个重要原因。⑤ 主要与城市化影响相关的地面观测资料系统偏差,可以部分解释现有分析表明的短历时强降水事件频率和累计降水量增加现象,同时也很可能是城市台站小雨和痕量降水事件频率明显下降的另一重要原因。

     

    Abstract: A few of features of long-term precipitation changes have been reported for mainland China for the last decades. The understanding of causes for the observed precipitation trends, however, is lacking. This paper comprehensively analyzes the long-term changes of multi-indicators of precipitation and atmospheric moisture over mainland China, the paleo-precipitation variations over representative areas, and the previous studies related to observed changes and possible causes of precipitation. The following conclusions are drawn: ① There is an obvious regional difference of recent precipitation trends in the country, but no significant long-term change is detectable over the past century or decades for mainland China on a whole. Frequency and amount of intense precipitation or rainstorms appear to increase over the last decades, and frequency of light rain events especially the trace rain events experiences a highly significant decrease over the same time period. ② Reanalysis data (NCEP/NCAR and ERA-Interim) shows a general increase in atmospheric moisture net budget over the last 3 decades, and sounding data and surface observations show significant upward trends of atmospheric perceptible water or specific humidity over the last decades. Tree-ring data and historical documental records indicate that the recent changes of precipitation are well within the ranges of historical natural variability, except for northeastern part of the Qinghai-Tibetan Plateau where the annual precipitation of the last century reconstructed based on tree-ring data seems to surpass the averages of any single century over the last ten centuries. ③ Instrumental observations of the last century show a distinct characteristic of multi-scale quasi-periodicals for annual total precipitation in the North China Plain, with each of them corresponding to the recognized variations of external forcings or internal modes of climate system, indicating the possible influence of natural forcings and variability on precipitation. The influence of increased atmospheric greenhouse gas concentration on precipitation in mainland China on a whole or in the eastern monsoon region of the country can hardly be detected, though the precipitation changes of Northwest China based on proxy data, instrumental data and modeling data are generally consistent with the theory expectation. ④ Weakening of regional surface wind speed is causing a systematic bias in observations of precipitation, and this is very likely to have led to, at least partially, a false upward trend of northern winter snowfall and annual intense precipitation frequency through increasing the catch-rate of rain gauges. The rising level of aerosols concentration in atmosphere is likely to be another major reason for the upward trend of intense precipitation frequency, and it is very likely to be one of the most important causes for the wide-spread decline of light and trace rain events in the monsoon region. ⑤ The data biases of the current observational data related to urbanization effects very likely account for an additionally substantial part of the reported increase in short-duration intense precipitation frequency and amount, and also for a large part of the observed decline of light and trace rain frequency in eastern monsoon region of the country.

     

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