《Table 2.The climatology of the vertical mass flux in the tropics at100 hPa and 70 hPa (2πa× (Ψ*max-

  提示：宽带有限、当前游客访问压缩模式

本系列图表出处文件名：随高清版一同展现

《"Evaluating the Brewer–Dobson circulation and its responses to ENSO, QBO, and the solar cycle in different reanalyses"》

1. 获取 高清版本忘记账户？点击这里登录

1. 下载图表忘记账户？点击这里登录

The linear trend of the tropical upward mass flux is also shown for each reanalysis during 1979–2010（gray lines）in Figures 3 and 4The decreasing trend of the BDC in ERA40 and ERAIN has been reported in recent studies（Fig.3 in Iwasaki et al. （2009），Fig.9 in Seviour et al.（2012）；Fig.14 in Abalos et al.（2015），Fig.2 in Wang WG et al.（2015），and Fig.5 in Miyazaki et al.（2016）） ，which is also confirmed at 100 hPa and 70 hPa（Figures 3c，4c）.Specifically，the linear trend of the tropical upward mass flux at 100 hPa in ERAIN is–2.61×108 kg/s/yr，which is above the 95%confidence level according to the Student’s t-test.However，the linear trend of the tropical upward mass flux varies with the datasets，as shown in Table 3.A slightly increasing trend of the BDC during 1979–2010is found in most reanalyses，even above the 95%confidence leve in CFSR，JRA25，NCEP1，and NCEP2.Therefore，the BDC trend inferred from the reanalyses has large uncertainty.Iwasaki et al（2009）also found that the yearly trends for the BDC are not reliably observed due to large diversity among the reanalyses，and Abalos et al.（2015）identified a strengthening of tropical upwelling from 100–10 hPa in JRA55 and MERRA when the reanalyses were extended to 2012.Consistent with the previous studies，the CESM1-WACCM also shows an increasing trend of the BDC.The deep branch of the BDC is mainly forced by extratropical wave activities，which shows a weak linear trend in both observations and models（Hu YY and Tung，2002；Rao J et al.，2015）.Consistent with the BDC trend，the EP flux divergence shows a negative trend in the extratropical stratosphere in most reanalyses，while the EP flux divergence in the mid-stratosphere shows a positive trend 30°N of poleward in ERAIN（not shown）.