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Dipole Types of Autumn Precipitation Variability over the Subtropical East Asia-Western Pacific Modulated by Shifting ENSO

2018-10-30

Hu, C., D. Chen, G. Huang and S. Yang. Dipole Types of Autumn Precipitation Variability over the Subtropical East Asia-Western Pacific Modulated by Shifting ENSO. Geophysical Research Letters, 2018, 45(17): 9123-9130.


Recent autumns have exhibited two dipole types of precipitation variability (DIPO1 and DIPO2) over the subtropical East Asia-western Pacific (SEAWP). Meanwhile, El Niño–Southern Oscillation (ENSO) has undergone significant mode shift, exhibiting as the eastern Pacific or central Pacific ENSO (EPSO or CPSO). Whether there was any physical linkage between the two remains unclear. Here we demonstrate for the first time that interannual variations of DIPO1 and DIPO2 are closely linked to EPSO and CPSO, respectively. Shifting ENSO modulates the patterns of SEAWP precipitation dipole mainly via changing the path of tropospheric moisture transport and the location of anomalous water vapor convergence/divergence due to different low-level cyclone/anticyclone activities induced by EPSO or CPSO. Further analysis shows that the interdecadal variability of SEAWP precipitation is also linked to the La Niña-like climate shift in 1998. Hence, our study provides some new insight into the ongoing hot debate on the shifting ENSO and increasing autumn drought in southeastern China.



Figure 1. (a) Normalized and detrended PC1, EPI, EPMCA-PRC, and EPMCA-SST. (b) Correlations (shading) and regressions (white curve; 0.5 mm day-1) of precipitation associated with PC1 shown in (a). (c) Same as (b), except for SST (curve; 0.5°C). The right panels are the same as the left panels, except for PC2 and for showing the CPI, CPMCA-PRC and CPMCA-SST in (d). Areas outlined by black thick lines indicate correlation at the estimated 90% confidence level.