The possible impact of solar activity on rainfall in Nepal: A case study

• Published in: Advances in space research Vol. 74; no. 5; pp. 2133 - 2143
• Main Authors: Gautam, Sujan Prasad, Silwal, Ashok, Baral, Bashu Dev, Adhikari, Binod
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2024
• Subjects: Climate change; Cross Wavelet Transform; Rainfall; Solar-climate interaction; Wavelet Transform Coherence; Rainfall; Climate change; Solar-climate interaction; Cross Wavelet Transform; Wavelet Transform Coherence
• ISSN: 0273-1177; 1879-1948
• DOI: 10.1016/j.asr.2024.05.075

This paper investigates the possible relationship between solar activity and monthly rainfall in Pokhara and Kathmandu cities in Nepal from the year 1968 to 2023. The study uses Cross Correlation Analysis (CCA) and wavelet analysis, the Cross-Wavelet Transform (XWT) and Wavelet Transform Coherence (WTC), to analyze the time series data. The CCA shows a strong positive correlation between the solar cycle and rainfall trend, with correlation coefficients of 0.77 and 0.76 and time lags of 18 months and 14 months at Pokhara and Kathmandu, respectively. The p-values, calculated to be < 0.0001 through the t-test, indicate that the observed correlations are statistically significant. The XWT results show a long-term ∼ 11-year common periodicity in solar cycle and rainfall. The WTC analysis confirms the local correlation between these two time series in time–frequency domain at a common periodicity. The results indicate that the monthly rainfall pattern in Nepal is closely related to the solar cycle pattern. Thus, solar activity likely plays a role in influencing rainfall trends in Nepal. This study shows that solar-climate interaction on a regional scale is complex and emphasizes the importance of understanding these relationships for predicting and managing climate change.