September 12, 2023
Journal Article

Impacts of the Boreal Summer Intraseasonal Oscillation on Precipitation Extremes in Indonesia


The relationship between boreal summer intraseasonal oscillation (BSISO) and precipitation extremes over Indonesia is investigated using observational datasets from 30 years (1987 – 2016) of rain gauge measurements and the gridded Asian Precipitation–Highly Resolved Observational Data Integration Toward Evaluation of Water Resources (APHRODITE) from 1998 – 2015. The results indicate that the frequency of daily extreme precipitation events in Indonesia (defined as total precipitation above the 95th percentile) during extended boreal summer (May-August) is significantly modulated by BSISO, especially over the western and northern regions. Under the influences of BSISO1, the probability of the precipitation extremes over Sumatra and Borneo increases by 20 - 120% (relative to the seasonal probability) during phases 1 to 3, and approximately 50 – 80% over the eastern part of Borneo and Sulawesi during phase 4. Under the BSISO2, the probability of the extremes increases up to 40% over Sumatra during phases 1 to 2 and up to 140% over Borneo and Sulawesi during phases 2 - 3. The increase in the probability of extreme summer precipitation is associated with enhanced large-scale moisture flux convergence and upward moisture transport induced by active phases of BSISO. These results provide potential information for medium-to-extended-range prediction of summer precipitation extremes in Indonesia.

Published: September 12, 2023


Muhammad F.R., and S. Lubis. 2022. Impacts of the Boreal Summer Intraseasonal Oscillation on Precipitation Extremes in Indonesia. International Journal of Climatology 43, no. 2022:1576-1592. PNNL-SA-177965. doi:10.1002/joc.7934

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