Guest Writer Feature: The Philippine Climate by Aldrin B. Gabuya


Today's guest writer is MindMover intern Aldrin Gabuya, a BS Astronomy Technology student from Rizal Technological University. 

         The Philippines has a tropical-oriented climate with only two seasons - compared to other countries which have four due to their geographical location near the equator - based on the amount of rainfall being experienced. These are dry and wet seasons. The dry season occurs every December to May, when numerous parts of the country experience less rainfall, while the wet season occurs in the remaining months of the year when several sections of country receive more rainfall.

                                      Climate seasons in the Philippines [Photo credit: thephilippines.ph]


The dry season can be classified as:

1) Hot and dry - from March to May, known as the summer months in the Northern Hemisphere, when the warm easterly trade winds coming from the Pacific Ocean prevail;

2) Cold and dry - from December to February, known as the winter months in the Northern Hemisphere, associated with the cool surge of the Northeast Monsoon (hanging amihan) blowing from the Siberian Region.

          The major consequences of the dry season, most especially in the summer months, are drought and on rare occasions, forest fires, greatly affecting the rice production and agriculture over the plains of Central Luzon.

         On the other hand, the wet season is often accompanied by several occurrences of rain and thunderstorms over different areas, either from the surge of the Southwest Monsoon (hanging habagat), numerous convective activity (most likely in the afternoon and evening), or tropical cyclone formations and passages. During this season, the country receives excessive rainfall on some occasions, creating flash floods over low-lying areas and landslides over mountainous regions. These cause severe damage over personal property, infrastructure, affecting livelihoods and causing loss of lives.

                               Drought affecting a plain field. [Photo credit: coraltriangle.blogs.panda.org]

                                      Cold and foggy weather in Baguio City during winter months 
                                                                        [Photo credit: newsinfo.inquirer.net]

                       Satellite image of Typhoon Ketsana making landfall over Metro Manila on Sept. 26, 2009
                                                                                  [Photo credit: blog.irrashai.com]

                                             Still-frame image of lightning over Pasig City
                                                                       [Photo credit: rtuastrosoc.blogspot.com]

                                         A flash flood over a low lying area in Metro Manila
                                                                          [Photo credit: science.blurtit.com]


        The pattern of the occurrence of the two seasons can be altered mainly by the onset of the El Niño Southern Oscillation (ENSO), a 5-year quasi-periodic climate pattern where fluctuations in sea surface temperatures (SSTs) in the Pacific Ocean greatly affect the distribution of rainfall int he tropical regions through the locations of the convergence zones. During its warm phase (El Niño), prolonged dry season occurs in the country while during its cold phase (La Niña), the country receives greater than average rainfall.

                                                 Diagram showing the phases of ENSO [Photo credit: Gabuya, 2015]

          Locally, the climate of the Philippines has been classified into four, in accord to the distribution of rainfall over certain regions of the country. This is known as the Modified Corona's Climate Classification; named after Father J. Corona, who made a study about the designation of dry and wet seasons in the Philippines in the 1920's. He determined the dry season as that with less than 50 mm of rainfall or a month with more than 100 mm of rainfall, over a period of three or more months in a certain location. This climate classification system is still in use by DOST-PAGASA, despite some uncertainties.

From there, Fr. Corona classified the different climate types over areas of the country as follows:

TYPE I: There are pronounced two seasons; dry from November to April and wet during the rest of the year. Rainfall is at its maximum from June to September.

TYPE II: There is "no pronounced dry season", meaning there is no single dry month. Wet conditions are often experienced in areas under this climate type. Rainfall is at its peak during December to February, while the minimum happens from March to May.

TYPE III: There is "no pronounced maximum rain period". It has a short dry season lasting from one to three months, either from December to February or from March to May. This climate type is also quite similar to Type I since it has a short dry season.

TYPE IV: There is uneven distribution of rainfall throughout the years along areas under this climate type; either more or less. This climate type resembles Type II since it has no dry season.

                                                         Modified Corona Climate Classification and the Monsoons
                                                                                  [Photo credit: panahon.tv]


REFERENCES:

1. Gabuya, AB. (2015). Solar activity and landfalling tropical cyclone frequency in the Philippines (Undergraduate Thesis). Mandaluyong, Philippines: Rizal Technological University.

2. Pajuelas, BG. (2000). A study of rainfall variations in the Philippines. Science Diliman 12(1): 1-28. Retrieved from: journals.upd.edu.ph/index.php/sciencediliman/article/viewFile/227/194

3. Philippines climate. (n.d.) Retrieved from Silent Gardens website: http://www.silent-gardens.com/climate.php#.Va3nBvmqpBd

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