For the WBWD pattern during 1961-1979, the WPSH was weaker and shifted eastward.
In this study, the spatiotemporal variability of summer drought as presented by SPI3 over the MLRYRB is extracted by EOF decomposition, and the summer drought of the MLRYRB is mainly featured by three patterns, including (i) dry conditions in the whole MLRYRB (referred to as WBWD pattern), (ii) dry conditions in the southern part of the MLRYRB with wet conditions in the northern part (referred to as SDNF pattern), and (iii) wet conditions in the southern portion of the MLRYRB with dry conditions in the northern portion (referred to as SFND pattern).
For the WBWD pattern during 1961-1979, a meridional wave pattern of 500 hPa GPH anomalies presented over eastern Asia, with negative anomalies over the western subtropical Pacific and Sea of Okhotsk and positive anomalies shifted from Japan to the northwestern Pacific.
For the WBWD pattern during 1961-1979, the WPSH located eastward and was weaker than normal, which reduced the water vapor transport from its western flank to southern China.
(d) The scatter diagram of the PC1 versus PC2 for 1961-2013, in which the WBWD, SDNF, and SFND years are colored in red, blue, and green, respectively.
Caption: Figure 7: 500 hPa GPH (contour) and its corresponding anomalies (shading) (units: gpm) of the WBWD pattern in the summers of (a) 1966, (b) 1967, (c) 1972, and (d) 1978; blue lines denote the climatology of 5880 gpm.
Caption: Figure 8: Anomalies of vertically integrated water vapor flux (arrows, units: kg [m.sup.-1] [s.sup.-1]) of the WBWD pattern in the summers of (a) 1966, (b) 1967, (c) 1972, and (d) 1978.
Caption: Figure 9: 200 hPa GPH anomalies (shading) (units: gpm) of the WBWD pattern in the summers of (a) 1966, (b) 1967, (c) 1972, and (d) 1978; blue lines denote the climatology of 12480 gpm and black lines indicate 12480 gpm for the typical years.