INFLUENCES OF MADDEN-JULIAN OSCILLATION ON THE DIURNAL VARIATION NEAR NORTH KALIMANTAN COAST

• Main Author: Syadzwina, Najwa
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/81055
• Institution: Institut Teknologi Bandung

Each region within the Maritime Continent exhibits distinct diurnal rainfall variations, influenced by local geographical complexities, topographic conditions, and coastline shapes. The Madden-Julian Oscillation (MJO) phenomenon also affects the strengthening of diurnal rainfall variations. However, research on MJO across different phases hasyielded varied conclusions in various regions, especially spatially challenging to conclude the influence of M.10 on rainfall in Kalimantan. Hence, this study aims to analyze the impact of M.10 on diurnal rainfall variations in the Northern Coastal Kalimantan during 2001-2020. The Real-time Multivariate MJO Index (RMM) data are used to identify strong MJO events and categorize them based on the convective M.10 location. Global Precipitation Measurement (GPM) IMERG Final Run V06B satellite rainfall data are utilized for spatial distribution analysis of rainfall and diurnal rainfall variations using Hovmoller diagrams. ECMWF Reanalysis 5th Generation (ERA5) data are employed to analyze syn,optic­ scale atmospheric conditions and local land-sea circulation. The highest average intensity is observed in coastal areas. Positive (negative) rainfall intensity anomalies distribution occurs in the Northern Coastal Kalimantan and surrounding areas during MJO F4-F5 (F6-F7). The strongest diurnal rainfall variations occur during MJO F4-F5, and the weakest during F8-Fl. JYpically, inland rainfall peaks often occur at night, except during phases F4-F5 (early morning) and F2-F3 (afternoon). Meanwhile, oceanic areas experience rainfall peaks during daytime, except during F4-F5 (morning). The spatial distribution pattern of rainfall intensity anomalies is influenced by synoptic-scale atmospheric conditions and land-sea circulation (only synoptic­ scale atmospheric conditions), mutually supporting rainfall increase (decrease) during F4-F5 (F6-F7). Diurnal variations in rainfall intensity are a combination of MJO-related synoptic-scale atmospheric conditions and land-sea circulation, mutually supporting rainfall increase (decrease) during F4-F5 (F8-FJ). Diurnal variations in normalized rainfall deviation during various dominant M.10 phases are influenced by local land-seafactors, especially during F6-F7.