A modified multifractal detrended fluctuation analysis to study the precipitation across northeast India

Using multifractal detrended fluctuation analysis (MF-DFA), the pre-monsoon rainfall and Indian summer monsoon rainfall (ISMR) from 1871 to 2016 are examined in this work for northeast India. According to observations, rainfall during the pre-monsoon and summer monsoons both exhibit persistence and quasi-randomness. The generalized Hurst Exponent value indicates that the pre-monsoon rainfall time series and the summer monsoon rainfall time series have long-term positive auto-correlation. The fluctuation function obtained through MF-DFA by means of the slopes of ln(Fq(s)) against ln(s) plots is dominated by segments with significant variance, which leads us to believe that the rainfall time series related to the pre- and summer monsoon exhibit multifractal behaviour. The presence of multifractality in the pre- and summer monsoon rainfall time series is further substantiated through the association between the qth-order variance and the length scale.