IDENTIFICATION OF EXTREME RAINFALL SPATIAL PATTERN IN BORNEO ISLAND ON DECEMBER-JANUARY-FEBRUARY SEASON USING CLUSTERING METHOD
Floods often occur on Borneo Island in many different areas, especially during December-January-February (DJF) season. One of the causes of flooding is extreme rainfall. However, the spatial pattern of extreme rainfall that commonly occurs in Kalimantan during the DJF season and the atmospheric-ocea...
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| Format: | Final Project |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/65192 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Floods often occur on Borneo Island in many different areas, especially during December-January-February (DJF) season. One of the causes of flooding is extreme rainfall. However, the spatial pattern of extreme rainfall that commonly occurs in Kalimantan during the DJF season and the atmospheric-ocean conditions that trigger this pattern are still unknown. The spatial pattern of extreme rainfall can be grouped using the clustering method.
This study uses Global Satellite Mapping of Precipitation (GSMaP) data to identify extreme rainfall events, Reanalysis ERA-5 data to identify atmospheric-sea conditions that trigger extreme rainfall, and meteorological phenomenon index to identify related phenomena. The identification of extreme rainfall was carried out using the maximum extreme rainfall value of the Kalimantan domain in every time step with a 95th percentile threshold. K means clustering is applied to extreme rainfall event to classify the spatial pattern of extreme rainfall. Then, composite analysis and identification of related phenomena are carried out in each cluster to determine atmospheric-sea conditions and the phenomena that trigger them.
The results of this study indicate that from the 95 extreme rainfall events on Borneo Island during DJF season, there are five clusters of rainfall spatial patterns. C1 shows a wet anomaly in the western part of Kalimantan which occurs due to moisture transport anomaly from the Asia mainland with 45,5% of its members related to cold surge (CS). C2 shows a wet anomaly around the north of Kalimantan which occurs due to moisture transport anomaly from the Philippines with 60% of its members related to CS. C3 shows high rainfall around North Kalimantan. In C3 there is moisture transport anomaly towards the Philippines with 36,8% of its members related to phase 4 or 5 of Madden-Julian oscillation (MJO). C4 shows high rainfall around South Kalimantan and Central Kalimantan which is related to the moisture convergence anomaly in that area. Composite analysis on C4 did not show a significant anomaly pattern that caused the C4 pattern and also did not show a specific phenomenon. C5 shows high rainfall around the Sabah and West Kalimantan regions which is related to the moisture convergence anomaly in the region with 30,8% of its members related to the CS and Borneo vortex (BV) occurring simultaneously.
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