The impact of El Ni?o and the positive Indian Ocean Dipole on rainfall variability in the lndo-Pacific region

[ABSTRACT]In the tropics including the Indonesian maritime continent, the atmosphere is highly sensitive to sea surface temperature variations, especially on interannual time scales, which significantly affect precipitation and atmospheric circulation at these latitudes. Here we study the relative influence of the El Ni?o (EN) and positive Indian Ocean Dipole (pIOD) events on the Indonesian rainfall variability using long-term observational datasets (1948-2008) based on satellite as well as ground-based observations. The empirical orthogonal function (EOF) analysis of Indonesian rainfall anomaly is employed to extract the modes of variability relevant to the regional rainfall index, defined for three separate regions representing typical rainfall patterns. Since an ordinary correlation between IOD and Indonesian rainfall might be contaminated by the concurrent EN signal, partial correlation technique and composite analysis methods are used on the monthly rainfall anomalies in the three separate regions to extract the apparent teleco皿ection patterns. The analysis reveals that the pIOD impact on the rainfall is generally overwhelmed by that of EN when the two are in co-occurence. Nevertheless, it is found that the IOD influence remains high (most negative correlation) with a significance of above 95% confidence level after proper removal of the EN influence. Strong EN events influence all regions in Indonesia, whereas the effect of strong pIOD events is most remarkable in western and central regions. The relationship between pIOD and Indonesian rainfall seems to be sustained through pIOD (not negative IOD) occurring in the presence of El Ni?o events.

https://opac.ll.chiba-u.jp/da/curator/106633/

https://opac.ll.chiba-u.jp/da/curator/106633/ceresIntlSympo-14-P107.pdf

Chiba University. Center for Environmental Remote Sensing

千葉大学環境リモートセンシング研究センター

会議発表用資料

Proceedings of the CEReS international symposium = CEReS国際シンポジウム資料集

14

107

110

2008-11-13

publisher

環境リモートセンシング研究センター「CEReSシンポジウム資料集」