Rainfall variability over South-east Asia—connections with Indian monsoon and ENSO extremes: new perspectives
✍ Scribed by Kripalani, R. H.; Kulkarni, Ashwini
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 305 KB
- Volume
- 17
- Category
- Article
- ISSN
- 0899-8418
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✦ Synopsis
Seasonal and annual rainfall data for 135 stations for periods varying from 25 to 125 years are utilized to investigate and understand the interannual and short-term (decadal) climate variability over the South-east Asian domain. Contemporaneous relations during the summer monsoon period (June to September) reveal that the rainfall variations over central India, north China, northern parts of Thailand, central parts of Brunei and Borneo and the Indonesian region east of 120 E vary in phase. However, the rainfall variations over the regions surrounding the South China Sea, in particular the north-west Philippines, vary in the opposite phase. Possible dynamic causes for the spatial correlation structure obtained are discussed.
Based on the instrumental data available and on an objective criteria, regional rainfall anomaly time series for contiguous regions over Thailand, Malaysia, Singapore, Brunei, Indonesia and Philippines are prepared. Results reveal that although there are year-to-year random ¯uctuations, there are certain epochs of the above-and below-normal rainfall over each region. These epochs are not forced by the El Nin Äo/La Nina frequencies. Near the equatorial regions the epochs tend to last for about a decade, whereas over the tropical regions, away from the Equator, epochs last for about three decades. There is no systematic climate change or trend in any of the series. Further, the impact of El Nin Äo (La Nina) on the rainfall regimes is more severe during the below (above) normal epochs than during the above (below) normal epochs. Extreme drought/¯ood situations tend to occur when the epochal behaviour and the El Nin Äo/La Nina events are phase-locked.