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中国沙漠 ›› 2012, Vol. 32 ›› Issue (6): 1691-1701.

• 天气与气候 • 上一篇    下一篇

1947—2006年东半球陆地干旱化特征——基于SPEI数据的分析

石 崇1,2, 刘晓东1,3   

  1. 1.中国科学院地球环境研究所 黄土与第四纪地质国家重点实验室, 陕西 西安 710075; 2.中国科学院研究生院, 北京 100049; 3.西安交通大学, 陕西 西安 710049
  • 收稿日期:2011-12-14 修回日期:2012-02-05 出版日期:2012-12-20 发布日期:2012-02-05

Continent Drought Characteristics over the Eastern Hemisphere from 1947 to 2006: Analyses based on the SPEI dataset

SHI Chong1,2, LIU Xiao-dong1,3   

  1. 1.Institute of Earth Environment, Chinese Academy of Sciences, State Key Laboratory of Loess and Quaternary Geology, Xian 710075, China;
    2.Graduate University of Chinese Academy of Sciences, Beijing 100049, China;
    3.Xian Jiaotong University, Xi'an 710049, China
  • Received:2011-12-14 Revised:2012-02-05 Online:2012-12-20 Published:2012-02-05

摘要:

利用1947—2006年逐月全球陆地高分辨率(0.5°×0.5°)标准化降水蒸散指数SPEI(Standardized Precipitation Evapotranspiration Index)资料,分析了过去60 a东半球(40°S—80°N,20°W—180°E)陆地的干旱化趋势和变率、干旱面积变化、干旱事件的持续性和周期性以及可能的变化成因等。结果显示,东半球80%的陆地上目前处于干旱化进程中,其中北非及中蒙边界等地干旱化趋势最为显著。干旱变率最大地区出现在非洲北部、中国青藏高原、中国西北东部及中蒙边界一带、俄罗斯中北部以及东北部。北非、中蒙边界中段及中国青藏高原地区也是持续性异常干旱事件出现频次最高的地区。基于功率谱的周期分析则显示,东半球大部分地区第一显著周期为1.5~3 a左右,中亚部分地区存在准4 a周期振荡,而北非地区存在准12 a周期的年代际变化。SPEI距平场的经验正交函数(EOF)分析第一模态反映了东半球陆地大部分地区干旱化总体上具有一致性,对应的时间函数与全球陆地气温距平相关系数高达0.81,表明全球变暖与东半球干旱化趋势有着紧密联系;第二模态对应的时间函数与超前8个月的南方涛动指数(SOI)的相关系数为0.60,因而大尺度的干旱周期性振荡受ENSO活动影响显著。

关键词: 干旱, 标准化降水蒸散指数, 经验正交函数, 全球变暖, ENSO

Abstract:

The characteristics of drought events over the continent in the Eastern Hemisphere (20°W-180°E,40°S-80°N), including the trend and variance, change in drought area, the persistence and periodicity, and possible causes, were analyzed in this paper by using the newest dataset of monthly Standardized Precipitation Evapotranspiration Index (SPEI) on a 0.5°×0.5° grid during 1947-2006. Results show that a drying trend is observed over more than 80 percent of the land areas in the Eastern Hemisphere, with the most obvious changes over northern Africa and China-Mongolia border. The regions with high variance are located in northern Africa, Tibetan Plateau, eastern Northwest China, China-Mongolia border, central-northern and northeastern Russia. The frequency of persistent drought events is extremely high in the northern Africa, Tibetan Plateau and the middle part of China-Mongolia border. The power spectral analysis reveals that the main periods of the drought oscillation are 1.5-3 years in most areas of the Eastern Hemisphere, 4 years in parts of central Asia, and 12 years in northern Africa, respectively. The analysis of empirical orthogonal function (EOF) of monthly SPEI anomalies indicates that the first mode (EOF1) shows a spatially uniform variation in most areas of the Eastern Hemisphere and a significant time correlation with the global mean land-surface air temperature (GMT). The high correlation coefficient (0.81) between the EOF1 and GMT means that the drying trends over these continents are closely related to global warming. The 8-month-lag correlation coefficient between the second EOF mode and the Southern Oscillation Index (SOI) exceeds 0.6, thus, the large-scale drought fluctuations are remarkably influenced by the El Nio-Southern Oscillation (ENSO).

Key words: drought, SPEI, EOF, global warming, ENSO