Investigating the Influence of Sunspot Numbers on Rainfall Variability in the Tropical Urban Area of Jabodetabek
Izatul Hafizah (a*), Fahmi Iman Alfarizki (b)

a) Geophysics and Meteorology Department, IPB University
Jalan Raya Dramaga, Bogor 16680, Indonesia
*izatulhafizah[at]apps.ipb.ac.id
b) Hacktiv8 Indonesia
Jalan Sultan Iskandar Muda No.7, Jakarta 12240, Indonesia

Abstract

Recent studies suggest that certain components of the Earths atmosphere, including rainfall variability, may be modulated by solar activity. Previous research in various regions has indicated potential linkages between sunspot numbers (SSN) and rainfall variability, although the characteristics of this relationship remain underexplored in tropical areas such as Jabodetabek, Indonesia.

This study aims to investigate the relationship between solar activity, represented by monthly SSN, and monthly rainfall variability in the Jabodetabek region over the long term. The data include monthly SSN and rainfall records from three BMKG stations across Jabodetabek, covering the period from 1985 to 2024. The analysis is conducted in three stages: (1) exploration of long-term variability using time series decomposition, (2) lagged cross-correlation analysis to assess potential delayed responses of rainfall to solar activity, and (3) identification of time-frequency domain relationships using Wavelet Coherence (WTC).

The findings of this study are expected to enhance understanding of the solar modulation of local rainfall variability and provide a preliminary reference for future research on astronomical drivers in tropical climate dynamics. The insights gained may also support climate adaptation and mitigation strategies in densely populated urban regions such as Jabodetabek.

Keywords: Sunspot Number- Rainfall Variability- Solar Activity- Wavelet Coherence- Tropical Urban Climate

Topic: Planetary Science