Diurnal rainfall cycle on small tropical island as seen by the 20 years half-hourly GPM-IMERG Satellite precipitation product

Abstract

The diurnal rainfall cycle is one of the dominant factors causing the high variability of convection activity in the Indonesian Maritime Continent (IMC) and vulnerable to climate change. Research on diurnal rainfall cycles in small tropical islands (areas less than 6150 km2), such as in the IMC is important because of the lack of understanding of its characteristics. The aims of current study are to investigate spatial characteristics of the diurnal rainfall cycle over Bali and their surrounding islands using half-hourly rainfall that estimated from the Integrated Multi-satellitE Retrievals for GPM (IMERG) for the period 2001-2020. Statistical scores employed to analyse the diurnal rainfall cycle characteristics is means analysis that done during year observation on long-term half-hourly and annually. The result of half-hourly IMERG rainfall estimation confirms for the first time that the rainfall in Bali contributes to the diurnal rainfall variability over the eastern part of Java Island. In Bali, rainfall start to initiate during 1200 local time (LT, +8 UTC) mostly began in high elevation located in the central part of the island, on the southern slopes of the mountain range. Rainfall over land continues to increase and slightly spread to the west until reaches its peak in 1400 LT. Rainfall began to depletion in the central of the island and at 1530 LT spread toward the western and merged with the existing rainfall in the east of Java Island. In the night (2200 LT), rainfall leaves Bali island towards the Bali strait and Bali sea.