Weather and Climate Systems

Philippine Tropical Cyclone Activity: Climatology, ENSO Impacts and Classification

Irenea Lodangco

02 October 2013, 1:00 PM

National Weather Center, Room 1313
120 David L. Boren Blvd.
University of Oklahoma
Norman, OK

About 70% of tropical cyclones (TCs) in the western North Pacific affect the Philippine region, with an annual average of 18 TCs over the period 1945-2011. TCs are the most devastating and costly natural disaster in the Philippines, in terms of human casualties and socio-economic consequences. TC activity in the Philippines runs year-round. The relatively quiet phase is from January to May, with less than one TC average per month, and is referred to as the less active season (LAS). The remainder of the year, June to December, is the more active season (MAS), with greater than one TC average per month. The two seasons differ in its characteristics expressed in mean seasonal metrics, including: frequency, landfall, total days, earliest start/end dates, latest start/end dates, season lengths, genesis and decay locations, and tracks.

ENSO is the dominant global mode affecting the Philippine TC activity. The impacts of ENSO depend on the season, the ENSO phase, and on the intensity of the TCs. Significant change in the mean seasonal metrics is observed as different ENSO phases influence the region.
Clusters analysis using K-means method was employed in classifying and regionalizing the genesis and decay locations and tracks of TCs in the domain. The classification has captured the longitudinal separations of TC formation. The formation region east of the Philippines is the most active having the highest number accounting to 398 cyclogenesis. TCs in the domain exhibit 5 distinct decay locations. The most prevalent area of dissipation is the cluster that represents Indochina or main Southeast Asia. Clustering the TC tracks has identified various track types by separating them into discrete numbers of patterns. The monthly distribution for each cluster of genesis, decay and tracks has shows that the seasonal cycle of TC activity differs from cluster to cluster.

Speaker bio

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