Diurnal Rainfall Characteristics over Western Sumatra Revealed by C-Band Weather Radar Observations during 2022-2024
Yudha Nugraha1, Marzuki Marzuki1*

1Department of Physics, Faculty of Mathematical and Natural Sciences, Universitas Andalas
*Email: marzuki[at]sci.unand.ac.id

Abstract

In recent years, identification of diurnal rainfall over Sumatra is generally using data from rain gauge, satellite observation, and reanalysis. This study aims to understand the diurnal rainfall characteristics from different perspective by using C-band ground radar observation, which is located in Padang, on the coast of West Sumatra. Radar reflectivity factor (Z) is used to obtain rainfall estimates (R) based on the Marshall-Palmer Z-R relationship (Z = 200R1,6). The diurnal characteristics for each topographic variation in the western part of Bukit Barisan, Sumatra were analyzed from accumulation, intensity, and occurrence of frequency during the period 2022-2024, both spatially and temporally. The results shows that mountainous region have the highest mean rainfall accumulation and occurrence frequency compared to others area with its diurnal peak time occurring in the afternoon (1400-1500LT). Meanwhile, in offshore region, accumulation and frequency of rainfall occur more often in the early morning (0300-0600LT). Another importance notes are rainfall diurnal on the western side of the Sumatra is more influenced by MJO phases rather than seasonal conditions. Whereas active MJO at phase 2-4 play a role in modulating amplitude and increasing mean rainfall accumulation and frequency, as well as accelerating the peak propagation time away from mountains.

Keywords: diurnal, rainfall, C-band radar, west Sumatra, Madden-Julian Oscillation

Topic: Earth Physics and Space Science