3.3.2 Characteristics of atmospheric circulation and
the correlation between rainfall over the Indochina
Peninsula and sea surface temperatures
In 2011, atmospheric circulation and convective
activity associated with the Asian summer monsoon were
generally stronger than normal (see Section 2.7).
Convective activity over the Indochina Peninsula was
enhanced in line with strong moist air flow from the Bay
of Bengal and an active monsoon trough in the lower
troposphere (Fig. 3.3.3).
The correlation between precipitation over the
Indochina Peninsula and sea surface temperatures (SSTs)
in the tropics was investigated using the CMAP data set
(Xie and Arkin 1997).
Figure 3.3.4 shows coefficients of correlation
between precipitation over the peninsula and tropical
SSTs based on the four-month average for June –
September. Negative coefficients with a 90% confidence
level are seen in the western equatorial Indian Ocean and
the western equatorial Pacific, while positive coefficients
with a similar confidence level are seen around the
equatorial date line region. In the four-month average for
June – September 2011, SSTs exhibited La Niña-like
characteristics in the tropical Pacific and were above
normal in the western Indian Ocean (Fig. 3.3.5). These
SST patterns are not consistent with those seen in the
statistical analysis.