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荀爱萍, 吴其冈, 胡雅君, 姚永红. 观测分析非洲南部地区土壤湿度异常对南半球大气环流的显著影响[J]. 大气科学, 2019, 43(3): 552-564. DOI: 10.3878/j.issn.1006-9895.1806.18116
引用本文: 荀爱萍, 吴其冈, 胡雅君, 姚永红. 观测分析非洲南部地区土壤湿度异常对南半球大气环流的显著影响[J]. 大气科学, 2019, 43(3): 552-564. DOI: 10.3878/j.issn.1006-9895.1806.18116
XUN Aiping, WU Qigang, HU Yajun, and YAO Yonghong. The Influence of Southern Africa Soil Moisture Anomalies on the Southern Hemisphere Atmospheric Circulation[J]. Chinese Journal of Atmospheric Sciences, 2019, 43(3): 552-564. DOI: 10.3878/j.issn.1006-9895.1806.18116
Citation: XUN Aiping, WU Qigang, HU Yajun, and YAO Yonghong. The Influence of Southern Africa Soil Moisture Anomalies on the Southern Hemisphere Atmospheric Circulation[J]. Chinese Journal of Atmospheric Sciences, 2019, 43(3): 552-564. DOI: 10.3878/j.issn.1006-9895.1806.18116

观测分析非洲南部地区土壤湿度异常对南半球大气环流的显著影响

The Influence of Southern Africa Soil Moisture Anomalies on the Southern Hemisphere Atmospheric Circulation

  • 摘要: 本文基于44年ERA40再分析月平均土壤湿度资料和大气环流变量场资料,去除ENSO遥相关以及趋势影响后,利用滞后最大协方差方法分析非洲南部地区土壤湿度分布与南半球大气环流异常之间的线性耦合。第一最大协方差模态的结果表明:在南半球冬季(Jun-Jul-Aug,6~8月)和夏季(Jan-Feb-Mar,1~3月),大气中类似南极涛动(Antarctic Oscillation,简称AAO)正位相的环流型与超前月份(最长时间达到5个月)的非洲南部地区土壤湿度的异常分布显著相关。基于土壤湿度变率中心的线性回归分析方法证实非洲南部地区其北部土壤湿度正异常、中南部土壤湿度负异常的空间分布对后期夏季和冬季的大气有显著的反馈作用。诊断结果显示由于夏秋季节和春季初夏非洲南部地区土壤湿度异常均有显著的持续性,同时对后期AAO产生持续增强作用,所以滞后最大协方差方法可以检测出它们对后期AAO的显著影响。以上非洲南部地区土壤湿度异常超前于南极涛动的信号,将有助于加强对土壤湿度反馈机制及其对南半球大尺度环流变率影响的认识。

     

    Abstract: This study uses maximum covariance analysis (MCA) to investigate the linear covariance between anomalous soil moisture at southern Africa and atmospheric circulation in the Southern Hemisphere (SH) based on the ERA40 reanalysis dataset. In the Southern Hemisphere winter (JJA, Jun-Jul-Aug) and summer (JFM, Jan-Feb-Mar), the atmospheric signal resembling the positive phase of the Antarctic Oscillation (AAO) is significantly correlated with persistent soil moisture anomalies in southern Africa that can be up to five months ahead in the leading MCA modes. Regression analysis based on the soil moisture anomaly centers from the MCA covariance patterns confirms that early-season positive soil moisture anomaly in the northern part of southern Africa and negative soil moisture anomaly in the central and southern part of southern Africa later have significant effects on winter and summer atmospheric circulation. Significant squared covariance of JJA (JFM) AAO seems to be related to persistent soil moisture anomalies in the preceding summer and autumn (spring and early summer) and their continuous and cumulative impacts on the atmosphere. The leading time of southern Africa soil moisture anomaly provides an implication for skillful predictability of large-scale atmospheric variability in the Southern Hemisphere winter and summer.

     

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