Abstract ID: 198
The impact of the BSISO on boreal summer rainfall anomalies in Indonesia
Lead Author: Donaldi Permana
Center for Research and Development – Indonesia Agency for Meteorology Climatology and Geophysics (BMKG), Indonesia
Keywords: BSISO, S2S, Indonesia, Rainfall anomalies, Boreal Summer
Abstract: The Boreal Summer Intraseasonal Oscillation (BSISO) is the dominant mode of intraseasonal variability of summer rainfall (May – October) in Indonesia. BSISO has quasi-oscillating periods of 30-60-days (BSISO1) and biweekly (BSISO2) time scale with northward/northwestward propagation. It has been affecting monsoon onsets, active/break phases of monsoon and monsoon seasonal mean. This study aims to investigate the general impacts of BSISO on summer rainfall anomalies in Indonesia. Impacts of the BSISO on daily rainfall anomaly during May to October have been evaluated using in-situ data from 86 stations during 1983 – 2012 (30 years) and remote sensing data using GPM IMERGV06 from 2001 – 2020 (20 years). BSISO1 and BSISO2 indices (phase and amplitude) were derived from APEC Climate Center (APCC). For BSISO 1, positive rainfall anomalies occurred over Sumatera, Kalimantan, North Sulawesi in phase 1-3 with higher amplitude in phase 2-3. In phase 3-4, most of Indonesia experienced increased rainfall, except north of Papua and north of Sumatra. While, the impact of BSISO phase 5-6 are opposite of phase 1-3 and most of Indonesia experienced decreased rainfall during phase 7-8 with more negative rainfall anomaly in phase 7. The BSISO 1 reflects the northward/northeastward shifting of rainfall anomalies over Indonesia. For BSISO 2, positive rainfall anomalies occurred over Sumatera (north, west), part of Kalimantan, Sulawesi, part of Java in phase 1-4 while eastern part of Indonesia experienced decreased rainfall during these phases. The impacts of the BSISO phase 5-6 are opposite of phase 1-3. While, most of Indonesia regions have experienced negative rainfall anomalies in phase 7-8, except north Sumatra and and northeast Papua. Generally, the results indicate that convectively active BSISO may increase the possibility of daily extreme rainfall in particular regions in Indonesia during May to October.
Co-authors:
Danang Eko Nuryanto, Center for Research and Development – Indonesia Agency for Meteorology Climatology and Geophysics (BMKG)
Nurdeka Hidayanto, Center for Research and Development – Indonesia Agency for Meteorology Climatology and Geophysics (BMKG)
Jaka Ivanda Paski, Center for Research and Development – Indonesia Agency for Meteorology Climatology and Geophysics (BMKG)
Erwin Makmur, Center for Research and Development – Indonesia Agency for Meteorology Climatology and Geophysics (BMKG)
Supriyanto Rohadi, Center for Research and Development – Indonesia Agency for Meteorology Climatology and Geophysics (BMKG)
Dwikorita Karnawati, Head – Indonesia Agency for Meteorology Climatology and Geophysics (BMKG)
