Climatic Insights on Academic Calendar Shift in the Philippinesphiljournalsci.dost.gov.ph/images/pdf/pjs_pdf/vol146no3/climatic... · climatic implications on AC shift in the Philippines

Philippine Journal of Science146 (3): 267-276, September 2017ISSN 0031 - 7683Date Received: 09 Dec 2016

Key words: academic calendar, climate extremes, climate resilience, Philippines, rainy season

Climatic Insights on Academic Calendar Shift in the Philippines

Department of Science and Technology-Philippine Atmospheric, Geophysical and Astronomical Services Administration

(DOST-PAGASA), Quezon City

*Corresponding author: [email protected]

Marcelino Q. Villafuerte II*, Edna L. Juanillo, and Flaviana D. Hilario

A number of Philippine universities have shifted their academic calendar (AC) from June-March (old AC) to August-May (new AC). Such AC shifting was primarily aimed to synchronize with other higher education institutions in Southeast Asia, which could provide flexibility for collaborative research works and eventually promote their global competitiveness. Considering the country’s climatic pattern, this study provides a comprehensive analysis on how the country’s climate could affect the recent AC shift. Subsequently, this study has revealed that school days seem to be better placed in the new AC than in the old AC, particularly in areas classified under rainy season Type 1, where rainy season occurs from mid-May to mid-October, and Type 3 (rainy season covers almost the latter half of the year). Such advantages of the new AC in comparison to the old AC include fewer rainy school days, lesser extreme rainfall events, and a reduced number of possible tropical cyclone-related cancellations of classes. However, a few downsides have been noted in implementing the new AC. It was revealed here that school days in the new AC, in areas characterized with rainy season Types 1 and 3, coincide with extremely hot days. Additionally, this study has revealed that graduation day seems to be better placed in the old AC than in the new AC because that day coincides with the rainy season and a higher possibility of tropical cyclone to occur in the latter, particularly over most areas in Luzon. These findings should therefore be considered in school-related activities to contribute in achieving a climate-resilient country.

INTRODUCTIONMost schools in the Philippines open their classes on the first Monday of June and close by the end of March; this has been in practice across the country since the school year 1965-66 when the Republic Act No. 4116 was promulgated (R.A. No. 4116). Several viewpoints, however, have been expressed recently to change the long followed academic calendar (AC) in the country because of some inconveniences experienced by the students, such as cancellation of classes during heavy rainfall events and tropical cyclone (TC) occurrence.

Additionally, some educational institutions would like to synchronize their AC following those of neighboring Southeast Asian countries. While several aspects have been raised for its infeasibility (see Chao 2014; CHED 2014), a legislative attempt has been made proposing for the AC shifting of both public and private educational institutions across the country (Olivarez 2014).

Although the legislative act proposed by Olivarez in 2014 did not materialize, some universities, particularly the University of the Philippines (system-wide, which means including its different campuses, elementary, and

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high schools), Ateneo de Manila University, De la Salle University, and University of Santo Tomas, decided to implement a new AC primarily aimed to enable a more flexible participation of students to exchange programs and eventually promote their global competitiveness. While the AC shifting adheres with the existing act governing the country’s educational calendar (i.e., R.A. No. 7797), and various forms of consultation and careful analyses have been done by those universities to consider the potential impacts of shifting their AC (see e.g., http://m.ateneo.edu/areyouready/challenge-change), the potential climatic impacts on such action have not yet been fully investigated nor documented. Hence, this study aims to investigate the potential impacts of the country’s climate conditions on the new AC implementation. This piece of research would then serve as a scholarly reference for those who are seeking information concerning the climatic implications on AC shift in the Philippines.

DATA AND METHODS

Climatic DatasetsBecause we primarily aimed to investigate the influence of Philippine climate on the new and the old ACs, we provide a comprehensive analysis focusing on the main climatic factors affecting school activities in the country [i.e., rainy season, TC occurrence, and the manifestations of rainfall and surface air temperature extremes]. The daily rainfall and maximum temperature datasets covering the period 1971-2013 were taken from 43 meteorological stations of the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), which have minimal missing data (each of them has <10% missing daily rainfall and temperature observations from 1971 to 2013). Such stations, although relatively fewer compared to other countries with a dense network of meteorological observation stations, are well distributed across the country (Figure 1). It has to be acknowledged, however, that the limited number of PAGASA stations considered in this study might not be able to represent the whole country given its complex topography and maritime climate. Note that meteorological variables are highly dependent on the topography of the area, and thus a separation of 10 km between stations might be required in some areas to enable representativeness (WMO 2007).

Extreme rainfall and temperature were also analyzed in this study. Here, the days with extreme rainfall are defined as those days with rainfall amount exceeding the 90th percentile of rainy days (days with rainfall ≥1 mm/day) from 1971 to 2013, hereafter referred to as R90. Similarly, extreme temperature is defined here as those days in which daily maximum temperatures exceeded the 90th percentile

of daily maximum temperature over the entire period of study (1971–2013), hereafter referred to as T90. Figures 2a and 2b show the 90th percentiles of rainy days and daily maximum temperature from 1971 to 2013 at every station considered in this study, which were used as the thresholds in identifying the R90 and T90, respectively.

The TC information used in this study is based on the approximate TC-center locations provided by PAGASA for all the TCs that existed in the Philippine area of responsibility (PAR) given at 6-hourly time intervals from 1971 to 2013. For presentation purposes, TC tracks were analyzed and presented in terms of how many times they existed within the 1°×1° grid boxes (without counting a single TC more than once if it stayed longer than 6 hr in a particular grid box) covering the PAR.

Definition of Rainy SeasonAlthough with distinct spatial and temporal variations, the onset of rainy season across the large Asian continent is generally found to coincide with the summer monsoon

Figure 1. Topographical map of the Philippines showing the geographical location of PAGASA stations considered in this study.

Villafuerte et al.: Climatic Insights on Academic Calendar Shift

Philippine Journal of ScienceVol. 146 No. 3, September 2017

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season because of the abundant rainfall it brings over most parts of the region (Wang & LinHo 2002). In the Philippines, the seasonality of rainfall can be characterized into four distinct types (Climate Types I–IV) using the Coronas classification (Coronas 1920), as well as its modified version (Kintanar 1984). Based on the modified Coronas classification updated by PAGASA (see for instance, http://www.pagasa.dost.gov.ph/index.php/climate-of-the-philippines, last accessed 28 Feb 2017), Climate Type I is characterized with two pronounced seasons — dry from November to April and wet from May to October. Climate Type II has no dry season and with discernible maximum rain period during the months of December, January, and February. Climate Type III resembles closely with Climate Type I, but with shorter dry season lasting from one to three months only, while Climate Type IV has almost similar characteristics with the Type II, which has no dry season and has an almost evenly distributed rainfall throughout the year. PAGASA declares the start of the rainy season in Climate Type I region when four out of seven meteorological stations, namely: Laoag, Vigan, Dagupan, Iba, San Jose, Ambulong, Iloilo, and at least two of the following stations located in greater Metro Manila area: Science Garden, Port Area, and

Sangley Point, have received a five-day total rainfall ≥25 mm, with three consecutive days having at least 1 mm/day. Additionally, the prevailing winds over the western Philippines should have westerly components from the surface to 850-hPa levels (PAGASA 2004).

Because our current investigation covers the whole country, we included the remaining areas not covered in the criteria defined by PAGASA in declaring the start of the rainy season. Hence, the onset and withdrawal dates of rainy season were identified in this study based on the pentad (five consecutive days) mean rainfall following a slight modifications done by Matsumoto (1997) from the method proposed by Ananthakrishnan et al. (1981), which has also been used in a number of recent studies (e.g., Hamada et al. 2002; Akasaka et al. 2007; Nguyen-Le et al. 2014). Based on that method, each year is divided into 73 non-overlapping pentads, which means that the 1st pentad corresponds to 1–5 January, the 2nd pentad as the period from 6 to 10 January, and so on until the 73rd pentad pertaining to 26–31 December. Afterwards, the mean rainfall was computed in each pentad (here, pentads with more than two days of missing values were excluded in the analyses) at every station considered in this study. To

Figure 2. Spatial distribution of the obtained 90th percentile of (a) rainy days (i.e., daily rainfall ≥1 mm/day) and (b) daily maximum temperature obtained from 1971 to 2013, which were used as the thresholds in identifying R90 and T90, respectively.



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minimize the noise in the obtained pentad-mean rainfall, a 1-2-1 filtering method was applied using Eq. (1). Let PRi correspond to the mean rainfall in pentad i, then the 1-2-1 filtered pentad-mean rainfall (𝑃𝑅�� ) is obtained as,

𝑃𝑅�� 𝑃𝑅�-1 +�(𝑃𝑅�) + 𝑃𝑅��1 (1) 4

where i is from 1 to 73.

The time series of 𝑃𝑅�� were then used in identifying the onset and withdrawal dates of rainy season. The onset (withdrawal) date of rainy season is defined in this study as the ith pentad in which the 𝑃𝑅�� initially exceeds (falls below) the climatologically averaged annual-mean pentad rainfall and continues to exceed (fall below) for at least three consecutive pentads. The old and the new ACs are then compared based on their timings relative to the climatological mean onset and withdrawal dates of rainy season.

Considering the distinct spatial and temporal features obtained in earlier studies for the seasonality of rainfall in the Philippines (e.g., Coronas 1920; Kintanar 1984), we investigated whether similarities in the climatologically averaged 𝑃𝑅�� obtained at every station similarly existed among a certain group of stations considered in this study. We then used the hierarchical clustering method proposed by Ward (1963), and eventually identified three groups of stations demonstrating similar rainy season characteristics (Figure 3a). The rainy season generally occurs from mid-May to mid-October for the Type 1 (see the uppermost panel of Figure 3c), which includes the stations located in the northwestern section of the country (marked with red-filled circles in Figure 3b), resembling the characteristics of the summer monsoon rainfall. The rainy season starts from October and lasts until the middle of February for rainy season Type 2 (middle panel of Figure 3c). Included in the rainy season Type 2 are the stations located on the eastern coasts of the Philippines (marked with blue-filled circles in Figure 3b). Twenty stations belong to the rainy season Type 3 (yellow-filled circles in Figure 3b). The rainy season in the Type 3 covers almost the latter half of the year (i.e., from pentad 31 to pentad 71), but the onset and withdrawal are not as pronounced as the other two rainy season types, and is characterized by an almost evenly distributed rainfall throughout the year (lowermost panel of Figure 3c).

RESULTS AND DISCUSSION

Climatic Insights on the Old and the New ACs

Rainy SeasonThe opening of classes based on the old and the new ACs (June and August, respectively) appears to coincide with the rainy season for Types 1 and 3, and with less rainy months for Type 2. Noteworthy, however, for those areas

classified as rainy season Types 1 and 3, is that the old AC (marked with orange horizontal bar in Figure 3c) covers almost the entire rainy season while the number of school days coinciding to rainy season is reduced approximately by 60 days in the new AC (marked with brown horizontal bar in Figure 3c). It can also be observed that the old AC covers more rainy months than the new AC over the areas classified as rainy season Type 2, particularly during the first two months after the classes have just started in the old AC (see, the middle panel in Figure 3c).

Nevertheless, graduation day appears to be placed favorably in the old AC for areas classified under rainy season Types 1 and 3 because the rainy season has not yet started over those areas on that day. Careful observation and monitoring of the weather condition should therefore be considered by the universities’ officials when scheduling the graduation day where the new AC has been implemented, particularly those that are located in rainy season Type 1 areas, which include Metro Manila being represented by the Science Garden meteorological station, and in areas classified as rainy season Type 3.

Extreme Rainfall and Temperature EventsWhile the rainy season, as presented in the previous subsection, is an important climatic aspect to consider in relation to the timing of the old and the new ACs over the country, extreme weather and climate events are more relevant to investigate because of their known disastrous impacts (e.g., Faustino-Eslava et al. 2011; Yumul et al. 2013). The challenge of dealing with extreme weather and climate events is similarly recognized in a global context, and the need for better understanding and managing the risks associated with extreme events has recently been emphasized (IPCC 2012). Hence, this section provides additional insights on the AC shift concerning extreme rainfall and temperature events, which are defined in section 2 as R90 and T90, respectively.

The monthly percentage of occurrence of R90 and T90 at the stations included in rainy season Types 1, 2, and 3 is depicted in Figure 4. It is observed that most of the days with extreme rainfall events (Figure 4a) coincide during the rainy season (see, Figure 3c for comparison). This means that the occurrence of R90 further supports the earlier findings concerning the timing of the old and the new ACs relative to the rainy season as discussed in the previous subsection. The percentage of occurrence of T90 depicting its annual cycle (Figure 4b), on the other hand, provides additional climatic insights on the old and the new ACs. Climatologically, the new AC covers almost 85% of T90 occurrences, which is approximately 60% higher than the old AC on the average, in areas classified as rainy season Type 1 (uppermost panel of Figure 4b). The percentage of T90 occurrences is almost similar between



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the old and the new AC (with less than 5% difference, on average) in areas classified as rainy season Type 2 (middle panel of Figure 4b). For areas classified as rainy season Type 3, school days in the new AC cover approximately 25% higher T90 occurrences, on the average, than in the old AC (lowermost panel of Figure 4b).

Such findings suggest that the new AC poses additional hazards to people exposed in such environmental condition (i.e., with extreme temperature events), which might affect their school-related activities. Seposo et al. (2015) showed that the minimum mortality temperature in Manila is about 30°C, and further revealed that the

increased risks of mortality were observed to surge for every 1°C rise in temperature. Note that the temperature thresholds that we used for defining T90 in almost all stations (see, Figure 2b) are way above the minimum mortality temperature identified by Seposo et al. (2015). It is therefore recommended that preventive measures related to health hazards posed by the increased T90 occurrences be done at the universities currently following the new AC (and those planning to implement it), particularly in areas classified as rainy season Types 1 and 3. We do suggest, however, that environment-friendly actions be considered when addressing such concerns so as not to

Figure 3. (a) Dendogram of PAGASA stations clustered based on their pentad-mean rainfall averaged from 1971 to 2013, (b) the spatial distribution of identified rainy season types based on (a), and (c) the climatologically averaged pentad-mean rainfall of individual stations (thin gray curves) and the mean of all the stations (thick black curves) grouped according to their rainy season types. The “O” and “W” in (c) denote the onset and withdrawal dates of rainy season, respectively; the black horizontal lines indicate the climatologically averaged annual-mean pentad rainfall. The period corresponding to the old AC (new AC) is marked with an orange (brown) horizontal bar in (c).



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exacerbate human contribution to global warming. Dahl (2013), for instance, discussed various ways in achieving a comfortable indoor temperature without resorting to the use of air conditioners.

TC OccurrenceThe Philippines is one of the countries frequently affected by TCs. Annually, there are approximately 19 TCs entering PAR, and in which 9 of them make landfall over the country (Cinco et al. 2016). Such TC occurrences, particularly those making landfall, in general, have led to suspension of classes. Hence, we investigate the timing of the old and the new ACs relative to TC occurrences

in the country.

The spatial distribution of TC tracks densities [i.e., the total number of TCs that existed in every 1° grid box during the entire period covered by the old AC (from 1 June to 31 March of the following year) and the new AC (from 1 August to 31 May of the following year) counted from 1971 to 2013] are shown in Figures 5a and 5b, respectively. It can be seen that the spatial distributions of TC occurrence are almost similar between the two ACs, with relatively much less TCs occurring over most of the areas in Mindanao and over the southwestern part of Palawan. Notably, however, more TCs occur over most parts of the country corresponding to the old AC than in the

Figure 4. Percentage of occurrence of (a) R90 and (b) T90 in each month for individual stations (thin curves) and their mean (thick curves) grouped according to rainy season types. Orange and brown horizontal bars mark the old AC and the new AC, respectively.



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Figure 5. Spatial distribution of the TCs that existed in every 1° grid box counted from 1971 to 2013 (i.e., TC tracks densities) corresponding to (a) the old AC, (b) the new AC, and (c) their difference (i.e., new AC minus old AC; negative values indicate fewer TCs in the new AC than in the old AC).

new AC. Such disparity between the two ACs can easily be discerned in Figure 5c, showing the difference taken between the new AC and the old AC’s TC tracks densities. Figure 5c further reveals that, with the exception of small portions of northeastern Mindanao and some areas in the western section of Visayas, school days in the new AC will likely experience a reduction of TCs by as much as 30–40% compared to the old AC, which translates to lesser TC-related cancellation of classes in the new AC in most parts of the country.

Nevertheless, the universities’ officials, who are now following the new AC, might need to carefully monitor the weather condition when scheduling their graduation day to avoid inconveniences. As shown in Figure 6a, graduation day in the old AC (assuming here as any day in March) could rarely be affected by the passage of a TC. In contrast, TC occurrence is likely to be observed in many parts of the country during graduation day (any day in May as the classes close around this month) in the new AC (Figure 6b).

CONCLUSIONSAs part of the government’s efforts in making the Philippines a climate-resilient country, this study provides a comprehensive analysis of the potential climatic impacts on AC shift implemented by some universities in the country. The old and the new ACs were compared based on their timings relative to the three main climatic factors affecting school days in the country (i.e., rainy season, days with extreme rainfall and temperature, and

TC occurrence). Subsequently, the study has revealed that school days coinciding with the rainy season in areas classified as rainy season Type 1 (i.e., rainy season occurs from mid-May to mid-October), which include Metro Manila as represented by the Science Garden meteorological station of PAGASA, and Type 3 (i.e., rainy season covers almost the latter half of the year) are approximately 60 days fewer in the new AC (from August to May) than in the old AC (from June to March). Such rainy school days are associated with extreme rainfall events, defined here as R90, which occur more frequently in the old AC than in the new AC. Additionally, more TC occurrences were observed from 1971 to 2013 in the old AC than in the new AC over most parts of the country, suggesting for fewer TC-related cancellation of classes in the new AC.

It has to be noted, however, that school days with extreme temperature (defined here as T90) occur approximately 60% and 25% higher in the new AC than in the old AC for areas classified as rainy season Types 1 and 3, respectively. Such findings imply an uncomfortably hot environment, which poses health risks and could affect school-related activities, over those areas where the new AC has been implemented. It is therefore suggested that precautionary measures related to extremely hot environment be taken at the universities currently following the new AC, which are located in areas classified as rainy season Type 1 (including Metro Manila) and Type 3. Additionally, this study has revealed that graduation day (sometime in March in the old AC and May in the new AC) seems to be well placed in the old AC than in the new AC. It has been shown that graduation day in the new AC coincides to the time when the rainy season has already started, particularly



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Figure 6. Spatial distribution of the TCs that existed in every 1° grid box counted from 1971 to 2013 (i.e., TC tracks densities) in (a) March and (b) May, where the graduation day could fall in the old AC and the new AC, respectively.

in Metro Manila and over those areas classified as rainy season Types 1 and 3. It is also important to stress here that careful monitoring of the weather condition is needed when scheduling the graduation day because TC occurrence is more likely to be experienced on that day in the new AC, which has rarely been experienced in the old AC.

The current findings reported in this study provide important insights on how the Philippine climate could possibly affect school-related activities concerning the AC shift (these are summarized in Table 1) that has recently been implemented at some universities (and those that are planning to implement the new AC) in the country. However, the potential implications of climate change have not been addressed in this study. Note that changes in extreme rainfall and temperature have already been observed in the Philippines (e.g., Cinco et al. 2014) and even linked to global warming (e.g., Villafuerte et al. 2015). Further investigations are therefore needed to determine how climate change might affect the current findings reported here. Nonetheless, the important points provided in this study, if considered, shall contribute to the government’s aim of becoming a climate-resilient country.

Table 1. Summary of the main advantages and disadvantages of the new AC against the old AC identified in this study.

Pros Areas Where Applicable

• Fewer school days coinciding with the rainy season Rainy Season Types 1 and 3

• Decreased number of school days with extreme rainfall Rainy Season Types 1 and 3

• Reduced TC-related cancellation of classes Most parts of the country

Cons 　

• More school days with extremely hot temperature Rainy Season Types 1 and 3

• Graduation day coincides with the rainy season Rainy Season Types 1 and 3

• More likely to be affected by a TC on graduation day Most areas in Luzon

ACKNOWLEDGMENTSA large part of this research was done during the first author’s two-month research visit at the Meteorological Research Institute (MRI), Japan; the Japanese Ministry of Land, Infrastructure, Transport and Tourism supported his entire visit there, which was made possible through



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the collaborative efforts exerted by Dr. Hidetaka Sasaki of MRI and Dr. Faye Cruz of Manila Observatory. The R statistical computing environment was used in the computations and in creating figures. We thank the three anonymous reviewers for providing their insightful comments, which contributed a lot in the improvement of this article.

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Climatic Insights on Academic Calendar Shift in the Philippinesphiljournalsci.dost.gov.ph/images/pdf/pjs_pdf/vol146no3/climatic... · climatic implications on AC shift in the Philippines