华西秋雨异常变化可导致旱涝、引发滑坡泥石流等次生灾害,对农业生产、社会经济和人民生命财产安全具有重要影响。因此,认识华西秋雨变化机制十分重要。我院周波涛教授等的近期研究揭示,华西秋雨(WCAR)与前期夏季巴伦支海冰(BSIC)的联系在本世纪初发生了明显的年代际减弱。1961-2002年期间,前期夏季巴伦支海冰减少可导致华西秋雨增多。但之后,两者联系变的不显著。进一步研究发现,在前一时期,夏季巴伦支海冰减少可通过改变热通量加热巴伦支-喀拉海地区的大气,进而触发从高纬途径巴尔喀什湖到西北太平洋的遥相关波列,造成东亚西风急流位置偏北以及西北太平洋副热带高压的加强,利于华西秋雨增加。在后一时期,由于海冰年际变率减小,海冰减少所激发的经向波列西移,无法影响到与华西秋雨相关的关键环流场,从而减弱了两者之间的联系。
Fig. 1. (a) EOF1 mode of autumn rainfall over West China. (b) Spatial distribution of correlations between the WCAR index and the sea ice concentration in early summer during 1961‒2020. Regions above the 90% confidence level are dotted. The selected region (75°-80°N, 35°-80°E) for the BSIC index is outlined by red frame. (c) Time series of the normalized WCAR and BSIC indices from 1961 to 2020. (d) Running correlations (red line) between the WCAR and BSIC indices with a 21-year window width. Orange (black) dashed line represents the correlation coefficient above the 90% (95%) confidence level.
文章信息:
Zhou Botao, Qian Jin, Hu Yuepeng, Li Hua, Han Tingting, Sun Bo. Interdecadal change in the linkage of early summer sea ice in the Barents Sea to the variability of West China Autumn Rain. Atmospheric Research, 2023, 287, 106717. https://doi.org/10.1016/j.atmosres.2023.106717