THE IMPACT OF POST-IOD (INDIAN OCEAN DIPOLE) ON RAINFALL IN INDONESIA INDEPENDENT OF ENSO (EL-NIñO SOUTHERN OSCILLATION)
IOD events are anomalous SST that occurs in Tropical Indian Ocean. This climate variability can affect rainfall in Indonesian region. There are many studies on IOD impacts on rainfall when this event occurs, and also the impacts on post-IOD event to Indonesian rainfall. It is known that not only IOD...
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| Format: | Final Project |
| Language: | Indonesia |
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| Online Access: | https://digilib.itb.ac.id/gdl/view/61687 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | IOD events are anomalous SST that occurs in Tropical Indian Ocean. This climate variability can affect rainfall in Indonesian region. There are many studies on IOD impacts on rainfall when this event occurs, and also the impacts on post-IOD event to Indonesian rainfall. It is known that not only IOD, rainfall in Indonesia is also affected by the ENSO phenomenon, hence to better understand the IOD effects to Indonesian rainfall, it is necessary to study it’s impact after removing the effect of the ENSO phenomenon.
This study examines the impact of post-IOD events on Indonesian rainfall during the period of 1979-2020. This study uses DMI and NINO 3.4 indices, ERA-5 dataset for SST, GPCP dataset for rainfall data, NCEP/NCAR Reanalysis Monthly dataset for velocity potential, and NOAA Interpolated Outgoing Longwave Radiation dataset for OLR values. Using the partial correlation method, analysis of post-IOD impact will be carried out on Indonesian rainfall to determine their relationship and it’s independence to ENSO. The same method will be applied to SST, OLR, and velocity potential to see the physical processes related to Indonesian rainfall.
The result of the analysis shows that post-IOD cause increase (decrease) on rainfall after its positive (negative) phase, especially on MAM season. After its dependence on ENSO is removed, western parts of Indonesian region show anomalous decrease on rainfall, while the eastern regions show anomalous increase on rainfall. Analysis on related variables to rainfall shows the western regions have anomalous reduce of rainfall due to lower SST heating (cooling) after ENSO effects are removed on positive (negative) phases, while the eastern regions show an anomalous increase on rainfall caused by convergence that occurs over the area after ENSO effects are removed.
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