INFLUENCE OF THE MADDEN-JULIAN OSCILLATION PHASE ON INDONESIAN PRECIPITATION IN TRANSITIONAL SEASON II (BOREAL AUTUMN)

• Main Author: Octaviana Silaen, Mariana
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/78975
• Institution: Institut Teknologi Bandung

Indonesia is the largest part of Maritime Continent where plenty of atmospheric and weather phenomena exist, which one of them is an intraseasonal oneknown as Madden-Julian Oscillation (MJO). This phenomenon influences the rainfall variability which also affects the life of human being. This study has investigated how the MJO affects the Indonesian precipitation during transitional season II (widely known as boreal autumn) in 13 years of time range (1998-2010) with 6 events of MJO, using the outgoing longwave radiation (OLR) as a proxy of convective activity and TRMM as the indicator of precipitation. The composite of these 6 events shows the enhancement and decreased of precipitation in each MJO phase. In wet phase (phase 4 and 5), the precipitaton augmentation is up to 2 – 4 mm/day (20 – 40%) on the Indian Ocean on the west of Java, and 2 mm/day (20%) on Makassar Strait and Sulawesi Sea. In the other hand, the precipitation diminution reaches 4 – 6 mm/day (60 – 100%) on the western coastal of Sumatra, western part of Kalimantan, and the western part of Papua. When it comes to the dry phase (phase 8 and 1), the precipitation degradation covers most of Indonesian area, around 2 – 4 mm/day (20 – 40%) on Java Sea, Makassar Strait, and the southern part of Kalimantan; and more than 6 mm/day (80 – 100%) on the Indian Ocean on the west of Java, Karimata Strait, Sulawesi Sea, and some parts of northern ocean of Papua. Generally, the precipitation diminution mostly occurs on phase 1 and 8, phase 6 and 7, and phase 4 and 5 on the western part of Indonesia. Based on student-t hypotesis, the whole region of Indonesia happens to have the influence of MJO, except the western coastal of Sumatra. Beside, the regions with the highest inversed-correlation of this propagation (between the anomalies of precipitation and OLR) are the eastern part of Kalimantan, Makassar Strait, western part of Sulawesi, and Sulawesi Sea, ranges between -0.4 and 0.8.