Influence of boreal summer intraseasonal oscillation on rainfall extremes in the Philippines

Olaguera, Lyndon Mark P.; Manalo, John A.; Matsumoto, Jun

doi:10.1002/joc.7495

Cited by 10 publications

(21 citation statements)

References 31 publications

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“…As previously mentioned, non‐TC vortices may also cause heavy rainfall and flooding events over the country. These disturbances may bring rainfall amounts that are higher than the 95th percentile extreme rainfall thresholds (e.g., Olaguera, Manalo et al ., 2022). During boreal winter, it has been noted in section 1 that CSVs are the common disturbances that induce heavy rainfall and flooding events over the country in this season.…”

Section: Resultsmentioning

confidence: 99%

“…One flooding case identified by Olaguera, Manalo et al . (2022) occurred from June 5–21, 2011 (https://ndrrmc.gov.ph/2-uncategorised/1669-flooding-incidents-in-region-x-region-xi-region-xii-and-armm) that is associated with non‐TC vortices. This flooding event was also recorded in the Dartmouth Flood Observatory Archive (https://floodobservatory.colorado.edu/Archives/index.html) and was caused by consecutive LPAs that later developed into TDs and TCs in the vicinity of the Philippines.…”

Section: Resultsmentioning

confidence: 99%

“…Previous studies have shown that the BSISO during the boreal summer season (i.e., JJASO) (e.g., Yoshida et al ., 2014; Moon et al ., 2018; Olaguera, Manalo et al ., 2022) and MJO during boreal winter (DJFMA) (e.g., Bagtasa, 2020; Kikuchi, 2020) can modulate the formation of tropical vortices that eventually develops into TCs. The presence of these ISO modes changes the background circulation that are favourable for the formation of TCs (e.g., Yoshida et al ., 2014).…”

Section: Resultsmentioning

confidence: 99%

“…As for the BSISO, TC genesis over the western North Pacific is enhanced during Phases 5 to 8 of the BSISO. Olaguera, Manalo et al (2022) examined the extreme rainfall events over the Philippines associated with the BSISO and found that most TC induced extreme events over the country also occur in these phases. The mean daily rainfall of all days with significant BSISO events in the eight phases of the BSISO are shown in Figure S3.…”

Section: Impact Of Bsiso and Mjomentioning

confidence: 99%

“…This HRF event was caused by a westward propagating low-pressure system over the island that interacted with a cold surge. Olaguera, Manalo et al (2022) examined the long-lasting flood events over the Philippines in relation to the different phases of the boreal summer intraseasonal oscillation (BSISO). One such flood event occurred in June 2011 over Mindanao Island, which has been associated with a continuous rainfall enhanced by a low-pressure system to its east (https://reliefweb.int/sites/reliefweb.int/files/resources/ Full_Report_1263.pdf).…”

Section: Introductionmentioning

confidence: 99%

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The contribution of non‐tropical cyclone vortices to the rainfall of the Philippines

Olaguera

Matsumoto

Manalo

2022

Intl Journal of Climatology

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Weaker disturbances than tropical cyclones (TCs) such as tropical depressions and cold surges can significantly induce heavy rainfall and flooding events over the Philippines. However, the analysis of these disturbances including their rainfall contributions are often neglected in previous studies. As the first attempt to address this research gap, this study investigates the rainfall contribution of non‐TC vortices over the Philippines from 1979 to 2020. Only those rainfall‐producing non‐TC vortices that formed and appeared within a 500‐km radius from the Philippine coastline were examined in this study. A total of 7,686 non‐TC vortex days (50% of the total days during the analysis period) were identified. The mean rainfall contribution of these non‐TC vortices was found to be highest over the northeastern Mindanao Island (80–90% of the mean daily rainfall) and lowest over the central and western regions of Luzon Island (50–60%). Seasonal analysis of the occurrence frequency of these vortices shows that they are most frequent during the December–February (DJF) season. In this season, the rainfall contribution may increase to 50–80% of the mean daily rainfall over the whole country, while in the other seasons, the rainfall contribution may only increase to as much as 60%. Higher frequency of extreme rainfall days associated with these non‐TC vortices were also found during the DJF season. The frequency of occurrence and percentage rainfall contribution of these non‐TC vortices in relation to the different phases of the Boreal Summer Intraseasonal Oscillation (BSISO) during boreal summer (June–October) and the Madden–Julian Oscillation (MJO) during boreal winter (December–April) were also examined. Higher frequency and percentage rainfall contribution over the country were found during Phases 4–6 of both the BSISO and MJO, during which their respective active convections transition from the Maritime Continent to the western North Pacific.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Impact Of Bsiso and Mjomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The contribution of non‐tropical cyclone vortices to the rainfall of the Philippines

Olaguera

Matsumoto

Manalo

2022

Intl Journal of Climatology

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Quantifying the influence of the Madden–Julian oscillation on rainfall extremes during the northeast monsoon season of the Philippines

Olaguera,

Manalo,

Bathan

et al. 2024

Atmospheric Science Letters

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This study investigates the impact of the Madden–Julian Oscillation (MJO) on the extreme rainfall events across 11 eastern coastal stations during the northeast monsoon season (November to March) over the Philippines from 1979 to 2019. The contribution of synoptic systems to these extreme rainfall events such as tropical cyclones (TCs), low‐pressure systems (LPS), cold surges (CS), and other disturbances as they coincide with a strong and active MJO were quantified. The results show that the probability of extreme rainfall occurrence increases first to as much as 20% in the southernmost stations in Phase 4. Then, it increases to more than 60% in central‐eastern stations in Phase 6. The extreme rainfall events were then classified into: MJO‐only, TC‐MJO, TC‐nonMJO, LPS‐MJO, LPS‐nonMJO, CS‐MJO, CS‐nonMJO, and others. The percentage contribution of MJO only, TC‐MJO, LPS‐MJO, and CS‐MJO to the total extreme rainfall events ranges from 9% to 16%, 0% to 3%, 2% to 4%, 1% to 9%, respectively. The relationship between MJO and flooding events in the Philippines was also examined. About 28 flood events or 266 flooding days were identified during the analysis period, wherein 50% of these events coincidentally occurred during strong and active phases of MJO.

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Impacts of the boreal summer intraseasonal oscillation on precipitation extremes in Indonesia

Muhammad

Lubis

2022

Intl Journal of Climatology

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The relationship between boreal summer intraseasonal oscillation (BSISO) and precipitation extremes over Indonesia is investigated using observational datasets from 30 years of rain gauge measurements and the gridded Asian Precipitation-Highly Resolved Observational Data Integration Towards Evaluation of Water Resources from 1998 to 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 1-3 and approximately 50-80% over the eastern part of Borneo and Sulawesi during phase 4. Under BSISO2, the probability of the extremes increases up to 40% over Sumatra during phases 1 and 2 and up to 140% over Borneo and Sulawesi during phases 2 and 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 the active phases of BSISO. These results provide potential information for medium-to extended-range predictions of summer precipitation extremes in Indonesia.

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Influence of boreal summer intraseasonal oscillation on rainfall extremes in the Philippines

Cited by 10 publications

References 31 publications

The contribution of non‐tropical cyclone vortices to the rainfall of the Philippines

The contribution of non‐tropical cyclone vortices to the rainfall of the Philippines

Quantifying the influence of the Madden–Julian oscillation on rainfall extremes during the northeast monsoon season of the Philippines

Impacts of the boreal summer intraseasonal oscillation on precipitation extremes in Indonesia

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