The possible association between summer monsoon rainfall in India and sunspot numbers

Studies are presented on the association between mean annual sunspot numbers (SNs) and the summer monsoon rainfall over India. Sunspots are related directly to solar magnetism, which governs the source of the solar wind. SN is correlated with the 10.7 cm solar flux, a quantity measured by remote sensing techniques. The statistical properties of the time series for SN and summer monsoon rainfall were studied and it was found that, although the SNs exhibit persistence, this is not the case for the mean annual summer monsoon rainfall. The cross-correlations were also studied. After a Box–Cox transformation, a time spectral analysis was conducted and it was found that both of the time series have an important spectrum at the fifth harmonic. A neural network model was developed on the data series averaged continuously over 5 years and this neural network could be used to establish a predictor–predictand relationship between the SNs and the mean yearly summer monsoon rainfall over India.