A climatological study of the wet and dry conditions in the pre‐summer monsoon season of the Philippines

Olaguera, Lyndon Mark P.; Matsumoto, Jun

doi:10.1002/joc.6452

Cited by 12 publications

(7 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Before the monsoon break period, rainfall in all the stations increases to as much as 38 mm⋅day −1 , except for Laoag station, where the rainfall first peaks at Lag −14 and exceeds 50 mm⋅day −1 . This location frequently experiences heavy rainfall events associated with shearlines (Olaguera and Matsumoto, 2020). During the monsoon break period, the rainfall drops below 5 mm⋅day −1 in all the stations and increases again to about 10 mm⋅day −1 after Lag +6.…”

Section: Resultsmentioning

confidence: 99%

A climatological analysis of the monsoon break following the summer monsoon onset over Luzon Island, Philippines

Olaguera

Matsumoto

Kubota

et al. 2021

Intl Journal of Climatology

Self Cite

View full text Add to dashboard Cite

This study investigates the climatology of the monsoon break following the onset of the summer rainy season over Luzon Island (120−122.5° E, 13−22° N) in the Philippines from 1979−2017. The first post-onset monsoon break is remarkable in stations located over the north and central Luzon Island and occurs climatologically in early June. Composite analysis of the large-scale circulation features during the monsoon break period shows that this break is associated with the westward extension of the western North Pacific Subtropical High (WNPSH), which weakened the monsoon southwesterlies and induced enhanced low-level divergence over Luzon Island. The westward extension of the WNPSH may be facilitated by the phase change of the boreal summer intraseasonal oscillation (BSISO). About 59% (23/39) of the monsoon break cases occurred when suppressed convection, associated with the dry phases of the BSISO, is apparent over the western North Pacific. This suppressed convection favors the westward expansion of the WNPSH. With the occurrence of the monsoon break in early summer, the seasonal march of the early summer monsoon over the Philippines can be divided into three phases: (1) the monsoon onset phase, which occurs between mid to late May under the influence of the westerly/southwesterly low-level winds, (2) the monsoon break phase, when rainfall decreases over Luzon Island in early June, and (3) the monsoon revival phase, when rainfall increases again due to the intrusion of monsoon southwesterlies over the Philippines. This study highlights the complex features of the summer monsoon onset and the impact of the WNPSH on the local climate of the Philippines in early summer.

show abstract

Section: Resultsmentioning

confidence: 99%

A climatological analysis of the monsoon break following the summer monsoon onset over Luzon Island, Philippines

Olaguera

Matsumoto

Kubota

et al. 2021

Intl Journal of Climatology

Self Cite

View full text Add to dashboard Cite

show abstract

“…The lower boundary of the negative meridional gradient of equivalent potential temperature ( e925hPa y ) can be used to locate the mean position of the cold front (e.g., Olaguera and Matsumoto 2020;Olaguera et al 2021), as shown in Fig. 2a, c, e, and g and superimposed with the winds at 925 hPa (WINDS 925hPa ).…”

Section: Synoptic Conditions During the January 2009 Hrfmentioning

confidence: 99%

“…They further noted that the presence of a westward propagating low-pressure area over Mindanao Island further enhanced the interaction between the warm easterlies over the tropical region and cold northeasterlies. The impact of cold surge shearlines is also observed during pre-summer (e.g., Olaguera and Matsumoto 2020) where it contributes to the pre-summer monsoon rainfall of the northern Philippines. Based on these aforementioned studies, it is recognized that the cold surge shearline is another synoptic-scale system that induces HRF events over the country especially during the northeast monsoon season.…”

Section: Introductionmentioning

confidence: 99%

Synoptic conditions and potential causes of the extreme heavy rainfall event of January 2009 over Mindanao Island, Philippines

et al. 2021

Self Cite

View full text Add to dashboard Cite

This study investigates the synoptic conditions that led to the heavy rainfall/flood (HRF) event in Mindanao Island, Philippines (122 −127°E; 5 −10°N), on January 2009 (JAN2009 HRF) that are less emphasized in previous works. Extensive flooding was reported over Cagayan de Oro City in the northern part of Mindanao, where the rainfall on January 10, 11, and 13, 2009, exceeded the 99th percentile of daily rainfall records of all January of the city from 1979 to 2017 by almost two times. A similar exceedance was also felt in Hinatuan station over the eastern coast of Mindanao Island on January 15, 2009. The interaction of a cold surge shearline over the northern Mindanao Island and the warm tropical easterlies led to enhanced moisture convergence. The warmer air mass is forced to ascend by the advancing colder air mass because it has lower density than the colder air mass. The enhanced moisture convergence and buoyancy difference by the air masses led to enhanced ascent and consequently rainfall along the cold surge shearline. Further analysis shows that enhanced anomalous easterly and northerly winds at 925 hPa are apparent over the Philippines. The anomalous easterly winds sustained the supply of warmer easterlies and collaboratively interacted with the northerly winds that supplied colder temperature air mass.The climatology of this HRF event was examined for all January from 1979 to 2017. The authors identified 15 other cases that are similar to the JAN2009 HRF event and performed lag composite analyses. The results show that the occurrence of these HRF events is facilitated by the southward expansion of the high-pressure system to the north of the Philippines, enhanced cold and warm temperature advections, and enhanced moisture convergence along the cold surge shearline. The results of this study have important implications for disaster mitigation during the northeast monsoon season when rainfall activities are, in general, less intensive over this region.

show abstract

“…More quantitative analysis are needed to firmly present the effect of TCs on the rainfall over the Philippines. Moreover, in addition to TCs, some other synoptic systems, such as midlatitude front or disturbances (e.g., Olaguera and Matsumoto, 2019;Olaguera et al, 2020a), or local rain systems such as diurnally driven local circulation are also contributing to the rainfall. The contribution from these systems on climatological rainfall seasonal changes should also be studied in future.…”

Section: Discussionmentioning

confidence: 99%

“…The wind over the Philippines tends to have more southerly component in this season. This indicates that the confluence zone between the westerly and easterly shifts eastward in the east of the Philippines due to the eastward retreat of the WNPSH (Olaguera et al, 2018a(Olaguera et al, , 2018b(Olaguera et al, , 2020b. The monsoon trough is located in the central part of the Philippines.…”

Section: Climatological Features Of Rainfall and Low Level Circulationmentioning

confidence: 93%

Climatological seasonal changes of wind and rainfall in the Philippines

Matsumoto

Olaguera

Nguyen-Le

et al. 2020

Intl Journal of Climatology

Self Cite

View full text Add to dashboard Cite

Climatological seasonal changes of rainfall and lower tropospheric circulation in and around the Philippines are analysed by utilizing the TRMM 3B42 to obtain the 5‐day mean rainfall and ERA‐Interim wind data for the period 1998–2013. In particular, climatological onset and withdrawal processes of the southwest (SW) and northeast (NE) monsoon are investigated. It is found that the onset of the SW monsoon occurs abruptly in mid‐May almost simultaneously over the Philippines except in the southern region. The start of the SW monsoon in the Philippines occurs earlier in the north than in the south. In addition, a climatological increase in rainfall on the west coast precedes the SW monsoon arrival by approximately two pentads, due to tropical cyclone influences in some years. After the SW monsoon onset, the monsoon trough is located over the southern Philippines. In mid‐June, the monsoon trough begins to deepen, and migrates northward to the central Philippines, and easterly winds intrude shortly to the northern Philippines. Then, the entire Philippines is covered by the summer monsoon westerly in early July, which is followed by the rainfall peak over the west coast region occurring in early August. The SW monsoon begins to retreat from the north in mid‐September, and fully retreats from the Philippines rather suddenly in late September. In general, the rainfall amount in the west coastal region remains high for approximately 2 months after this wind reversal, showing relatively larger post monsoon rainfall due mainly to tropical cyclone effects. During the NE monsoon season, the rainfall centre in the east coast is located in the northern and central region until mid‐December. Afterwards it is anchored in the southern region from late December to mid‐March, indicating the fully established NE monsoon season.

show abstract

A climatological study of the wet and dry conditions in the pre‐summer monsoon season of the Philippines

Cited by 12 publications

References 27 publications

A climatological analysis of the monsoon break following the summer monsoon onset over Luzon Island, Philippines

A climatological analysis of the monsoon break following the summer monsoon onset over Luzon Island, Philippines

Synoptic conditions and potential causes of the extreme heavy rainfall event of January 2009 over Mindanao Island, Philippines

Climatological seasonal changes of wind and rainfall in the Philippines

Contact Info

Product

Resources

About