Geoscience Reference
In-Depth Information
China and North China. Compared with the previous stage, the abnormal
movement of EASM causes the precipitation to increase markedly and
brings much more floods to mid-lower Yangtze Valley, and the rainfall in
Northeast China increase a little. However, the precipitation in South China
and North China decrease obviously. In this period, the spatial distribution
pattern of the precipitation anomaly percentage “
,+”fromSouth
China, Yangtze River, North China to Northeast China (Fig. 6(c)).
,+,
−
−
(IV)
During the Period of 1994-2001
EASM break out in SCS in the 27th pentad early and the EASM's front is
north to normal in 27th and the north edge of EASM has reached South
China (Fig. 5(d)). The EASM's front was north to normal obviously during
28th-29th pentad and it stay at South China. And the front was also north
to normal obviously during 31st-32nd pentad staying at the mid-lower of
Yangtze Valley, but the front is south to normal in 35th pentad. Therefore,
the front of EASM mainly concentrates the middle-lower of Yangtze River
during 31st-35th pentad, bringing much more precipitation to this area.
The front was also south to normal during 38th-40th pentad and it mainly
stays at the lower of Yellow River during the 36th-40th pentad, causing
more rainfall there. In the west of 115
◦
E, the front is south to normal,
but it is north to normal a little in east of 115
◦
E and stay at Northeast
China during 42nd-43rd pentad. But the front was north obviously in 44th
pentad and 46th pentad, it is not retreat much and still it stay at Northeast
China in the 44th pentad and it retreats to Yangtze River and not to
South China as normal in the 46th pentad, EASM retreat south of 20
◦
Nin
the 47th pentad. The positive EASM's index anomalies cover South China
and the mid-lower of Yangtze Valley while negative anomalies cover North
China. The Southwesterly anomalies appear in South China (Fig. 7(d)). The
abnormal movement causes the precipitation increase markedly in South
China and Yangtze River and the percentage anomalies of rainfall reaches
above 30% in South China and the mid-lower of Yangtze Valley. Compare
with the previous stage, the precipitation increases much more in South
China and Yangtze River, especially in South China, but it decreases in
North China continuously and this lead to the serious drought in North
China. In this period, the spatial distribution pattern of the precipitation
anomaly percentage is “+, +,
−
, +” from South China, Yangtze River,
North China to Northeast China (Fig. 6(d)).
To summarize, as the EASM's movement exhibit three times
interdecadal shifts in 1965, 1980, and 1994, respectively, the advance and
retreat of EASM also exhibits interdecadal variability and this is the direct
