DIURNAL VARIATION OF PRECIPITATION IN SENTANI, PAPUA

• Main Author: Angela Damanik, Rira
• Format: Theses
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/86201
• Institution: Institut Teknologi Bandung

Rainfall in Sentani, Papua, shows significant variation due to its coastal location and surrounding mountainous terrain. Observational data from BMKG Sentani for the years 2018-2022 indicate that the highest rainfall intensity and the most frequent occurrences of rain take place during the early morning hours. This study aims to analyze the factors influencing precipitation formation in Sentani, specifically focusing on early morning rainfall, by examining atmospheric conditions, wind convergence, and the potential for convective system development. To analyze the patterns and variations in precipitation, we employed averaging methods and anomaly analysis of meteorological parameters relevant to precipitation formation. The data utilized include rainfall measurements from the Integrated Multi-satellite Retrievals for Global Precipitation Measurement (IMERG) Final Precipitation, with a spatial resolution of 0.1° × 0.1° for analyzing precipitation variability, and data from the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 with a resolution of 0.25° × 0.25°, encompassing meteorological parameters such as 2-meter surface temperature, zonal wind components (u), meridional wind components (v), vertical wind components (w), temperature and specific humidity at the 1000 hPa level, and Vertically Integrated Moisture Divergence (VIMD) to assess atmospheric circulation patterns affecting diurnal precipitation variation in Sentani. The results show that the highest intensity and frequency of precipitation occur during the DJF season, followed by MAM and SON, with the lowest rainfall observed during JJA. Early morning precipitation is prevalent throughout the year in the study area, showing the highest intensity and frequency during DJF and MAM. Precipitation in the study region tends to propagate from land towards the ocean, with a propagation pattern from west to east. Rainfall generally forms over land during the night and early morning, while from early morning to afternoon, precipitation is more predominant over the ocean and coastal regions. Specifically, Sentani has the potential for rainfall events throughout the year from afternoon to morning. This is attributed to the significant concentration of water vapor and the potential for convective cloud development. These convective systems can persist for extended periods due to the presence of a cool pool that supports the reformation of convective systems in the study area. Early morning precipitation is more intense during DJF and MAM due to meridional winds transporting moist air from the ocean to the land.