Indonesian rainfall variability observation using TRMM multi-satellite data

It is important to understand the characteristics of Indonesian rainfall within the world's climate system. The large rainfall in the Indonesian archipelago plays an essential role as a central atmospheric heat source of the Earth's climate system throughout the year. Monthly rainfall satellite data, measured by the Tropical Rainfall Measuring Mission (TRMM) 3B43 over the course of 13 years, were employed to analyse monthly means, total means, maximum and minimum variability, standard deviation, and the trends analysis of Indonesian rainfall variability. The rainfall estimated from satellite data was then compared to the rain gauge data over the Indonesian region to determine the accuracy level. The results show that oceans, islands, monsoons, and topography clearly affect the spatial patterns of Indonesian rainfall. Most high-rainfall events in Indonesia peak during the December-January-February (DJF) season and the lowest rainfall events occur during the June-July-August (JJA) season. Those conditions are associated and generated with the northwest and southeast monsoon patterns. High fluctuations between maximum and minimum monthly rainfall data of over 400mm month(-1) occur over Jawa (Java) Island, the Jawa Sea, and southern Sulawesi Island. A high annual and monthly rainfall typically occurs throughout Indonesia over island areas. The trend analysis shows an increasing trend in rainfall from 1998 to 2010 in Kalimantan, Jawa, Sumatra, and Papua. Decreasing rainfall trends occur along the west and south coast of Sumatra, eastern Jawa, southern Sulawesi, Maluku Islands, western Papua, and Bali Island.