Analysis of Daily Rainfall Characteristics Based on Quality Controlled Data in Sumatra (1985-2023)
Sudirman, Muhammad Irfan, Supari, Hamdi Akhsan, and Vefie Yonalia Putri

Doctoral Program in Natural Sciences, Faculty of Mathematics and Natural Sciences, Universitas Sriwijaya, Palembang, South Sumatra, Indonesia- Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Sriwijaya, Palembang, South Sumatra, Indonesia- Meteorology, Climatology, and Geophysics Agency (BMKG), Indonesia- Physics Education Study Program, Faculty of Teacher Training and Education, Universitas Sriwijaya, Palembang, South Sumatra, Indonesia.

Abstract

This study analyzes daily rainfall characteristics with quality control across Sumatra from 1985 to 2023. Daily rainfall data from 19 BMKG stations across ten provinces, from Aceh to Lampung, were analyzed to ensure reliability and consistency. Quality control procedures addressed common issues such as missing and abnormal data that may bias hydrometeorological analyses. The first and second quality control tests indicated a high data completeness level of 94 percent, categorized as very good. Further tests identified a few outliers with the highest daily rainfall intensities of 470 millimeters per day (Minangkabau), 430 millimeters per day (FL Tobing), 400 millimeters per day (Bengkulu), and 390 millimeters per day (Fatmawati Soekarno), although their occurrences were rare. In southern Sumatra, only single outlier events of 200 to 250 millimeters per day were found. Overall, extreme and very extreme rainfall outliers across Sumatra were below 1 percent, indicating good data quality for subsequent trend analyses.

Keywords: rainfall, quality control, outlier, Sumatra, BMKG

Topic: Physics and Applied Physics