Geoscience Reference
In-Depth Information
areas of South China. The main reason is that the Pacific-Indian Ocean
SSTA remains a quasi-normal state.
24
Previous researches of the influence of El Nino on summer climates in
China already showed that during El Nino year, more rainfall above average
occurred in the Changjiang-Huaihe River Basin,
25
,
26
and low temperature
and more rainfall in Northeast China.
27
,
28
Our results involving the pure
El Nino are almost the same as those previously researched. Consequently,
we can conclude that the analyses in this section are credible to a certain
degree.
3.2
. Rainfall in India
Although the relationship between the Indian summer precipitation and
ENSO in recent years is some what weakened, on the whole, the summer
anomalous rainfall in India is still a typical example of the ENSO impacts.
One of the causes of the weakened relationship between the Indian summer
rainfall and ENSO is considered the influence of the Indian Ocean SSTA.
If the composite effect of the SSTA in both the Pacific and the Indian
Ocean is taken into account, it may make the relationship between our
presented composite mode and the Indian summer rainfall become relatively
good. Figure 5 shows the Indian summer rainfall corresponding to the pure
El Nino year and the positive phase of the PIM, respectively. More rainfall
than average occurs in the middle part of India, less rainfall happens in the
northern part and the southwestern part of India corresponding to the pure
El Nino year (Fig. 5). The whole India receives substantially less rainfall
than the average corresponding to the positive phase of the PIM (Fig. 5(b)).
(a)
(b)
Fig. 5. Composites of precipitation anomalies from the precipitation reconstruction
over land (PREC/L) in summer for positive phase of (El Nino) of the ENSO mode (a),
(b) positive phase of the PIM. Unit: mm/JJA. The dark shading and light shading show
the
-test significance at the 0.05 and 0.1 levels, respectively.
t
