Hurst exponent approach through rescaled range analysis to study the time series of summer monsoon rainfall over northea
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ORIGINAL PAPER
Hurst exponent approach through rescaled range analysis to study the time series of summer monsoon rainfall over northeast India Srishti Pal 1 & Shrutinil Dutta 1 & Tamanna Nasrin 1 & Surajit Chattopadhyay 1 Received: 16 April 2020 / Accepted: 20 July 2020 # Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract The present work reports a study on the behavior of the time series of rainfall during the summer monsoon (June–September) in northeast India. It has been observed through hypothesis testing that although a normal distribution fits the time series, no persistence forecast is possible as indicated by the low value of the Lag-1 autocorrelation coefficient (0.041). A linear regression over time is not a good fit. Subsequently, the intrinsic behavior of the time series has been explored through Hurst exponent (H) computed using rescaled range analysis. The value of the Hurst exponent is in the range of 0 < H < 0.5, and from this range, it could be understood that long-term switching is expected to exist between high and low values in adjacent pairs. However, when the Hurst exponent value is being low, the summer monsoon rainfall over northeast India has been thought of as characterized by volatility and roughness. Finally, the connectivity of the El Niño-Southern Oscillation (ENSO) to the Indian summer monsoon rainfall has been briefly discussed in light of the long-term behavior. Keywords Northeast IndiaSummer-monsoonRainfallHurst exponent
1 Introduction The prediction of the Indian summer monsoon (ISMR) with sufficient lead time has remained to be an important area to study for the Indian subcontinent because of the role of ISMR on the agricultural planning and the country’s GDP. It is reported in Subash and Gangwar (2014) that the ISMR can control the GDP of India even up to 22% by its influence on the agricultural practices. A delayed or early arrival of the monsoon may lead to drought or flood, and those have a gross impact upon the production of crops and the associated livelihood. Quite a significant number of studies have emphasized the predictability of its onset as well as withdrawal. The predictability of its onset as well as withdrawal has been studied by the meteorologists over the globe. In a study, Stolbova et al. (2016) reported a prediction methodology for monsoon timing using a critical transition precursor. They (Stolbova et al. 2016) identified some geographic regions to be used as observation locations that could * Surajit Chattopadhyay [email protected]; [email protected] 1
Department of Mathematics, Amity University Kolkata, Major Arterial Road, Action Area-II, New Town, Kolkata 700135, India
be utilized for the prediction of the dates of monsoon onset and withdrawal. It may be noted that, instead of depending upon the analysis of precipitation, the methodology proposed in Stolbova et al. (2016) explored air temperature and relative humidity and their proposed methodology could have a prediction of onset with 2-week lead time and withdra
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