Climatology of Precipitation Diurnal Cycle Over Java and Bali Island from IMERG V06 and Rain Gauge Data

The diurnal cycle in Java and Bali was examined using the Integrated Multi-Satellite Retrievals for the Global Precipitation Measurement (IMERG) final-run product, specifically the IMERG-F data. The dataset employed here comprises IMERG version 06 data from 2015 to 2020 and surface rainfall data obtained from rain gauge measurements. To understand this diurnal cycle, key precipitation metrics, namely precipitation amount (PA), precipitation frequency (PF), and precipitation intensity (PI), were defined. The spatial distribution of PA closely mirrors the pattern of average annual precipitation, with the highest levels observed in the western region, situated towards the southern part of Java Island, registering at 0.28 mm/h. This level gradually diminishes as one moves eastward from Java Island to Bali Island. Conversely, PF tends to be notably higher (9.6%) in the central areas of Java Island but decreases as one proceeds towards the eastern regions, encompassing Bali. In contrast to PA and PF, the average PI was elevated in the lowland areas of the southern part of Java and decreased with increasing topography. Notably, despite differences in the distribution of PA and PF averages, these disparities do not significantly impact the peak times of PA and PF. The peak periods of PA and PF in mainland areas are predominantly concentrated in the afternoon, specifically from 1500 to 1700 Local Standard Time (LST), consistent with rain gauge (RG) observations. In contrast to the peak times of PA and PF, the peak time of PI is dominant in the afternoon and early evening. This study's findings contribute to understanding the diurnal rainfall patterns in Java and Bali.