Complexities of Extreme Rainfall in the Philippines

Olaguera, Lyndon Mark P.; Cruz, Faye; Dado, Julie Mae; Villarin, Jose Ramon T.

doi:10.1007/978-981-19-2511-5_5

Cited by 9 publications

(4 citation statements)

References 48 publications

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“…Extreme rainfall events, which are associated with devastating floods, are one of the hazards that affect the Philippines. Various factors that contribute to these extreme rainfall events have been explored in recent studies and include, but not limited to, tropical cyclones (TCs), cold surges (CS), shearlines, MJO, BSISO, and non‐TC vortices (Abdillah et al, 2021; Bagtasa, 2017; Cayanan et al, 2011; Chen et al, 2015a, 2015b; Cruz & Narisma, 2016; Olaguera, Matsumoto, et al, 2021; Olaguera, Caballar, et al, 2021; Olaguera, Cruz, et al, 2022; Olaguera, Manalo, et al, 2022; Olaguera, et al, 2023; Olaguera & Matsumoto, 2020; Pullen et al, 2015; Racoma et al, 2022). Aside from the copious amounts of rainfall that each of the above factors may bring, these factors may also interact with the background circulation or with one another, which makes the extreme rainfall events in the Philippines more complex and severe (Olaguera, Cruz, et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

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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Section: Introductionmentioning

confidence: 99%

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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“…Additionally, we evaluated how the CMR affects characteristics such as movement speed, intensity, and wind strength, and how these characteristics are related to TC precipitation. The CMR induces monsoon blocking effects affecting precipitation over Luzon [15]; TCs contribute as much as 54% of precipitation along the western coast of Luzon [16]. Additionally, two major river basins of the Philippines are located within the boundaries of the CMR, with the Cagayan River basin to the east and the Pampanga River basin to the south of the mountain range.…”

Section: Introductionmentioning

confidence: 99%

The Effect of the Cordillera Mountain Range on Tropical Cyclone Rainfall in the Northern Philippines

et al. 2023

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In this study, we examined the sensitivity of tropical cyclone (TC) characteristics and precipitation to the Cordillera Mountain Range (CMR) in Luzon, Philippines. Using the Weather Research and Forecasting (WRF) model, we simulated eight TCs with four different CMR orographic elevations: Control, Flat, Reduced, and Enhanced. We found that at significance level α=0.05, TC intensity significantly weakened as early as 21 h prior to landfall in the Enhanced experiment relative to the Control, whereas there was little change in the Flat and Reduced experiments. However, throughout the period when the TC crossed Luzon, we found no significant differences for TC movement speed and position in the different orographic elevations. When a TC made landfall, associated precipitation over the CMR increased as the mountain height increased. We further investigated the underpinning processes relevant to the effect of the CMR on precipitation by examining the effects of mountain slope, incoming perpendicular wind speed, and the moist Froude Number (Fw). Compared with other factors, TC precipitation was most strongly correlated with the strength of approaching winds multiplied by the mountain slope, i.e., stronger winds blowing up steeper mountain slopes caused higher amounts of precipitation. We also found that individually, Fw, mountain height, and upslope wind speeds were poor indicators of orographically induced precipitation. The effects of mountain range on TC rainfall varied with TC cases, highlighting the complexity of the mountain, wind, and rainfall relationship.

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“…They found that the multiscale interaction of the MJO, the existing La Niña condition, and a cold surge led to the extreme rainfall event over the country during this period. This example clearly demonstrates the complexity of extreme rainfall events in the country (Olaguera, Cruz et al ., 2022).…”

Section: Introductionmentioning

confidence: 99%

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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Complexities of Extreme Rainfall in the Philippines

Cited by 9 publications

References 48 publications

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

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

The Effect of the Cordillera Mountain Range on Tropical Cyclone Rainfall in the Northern Philippines

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

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