Trend Analysis and Change Point Detection of Mean Air Temperature: A Spatio-Temporal Perspective of North-Eastern India

The climate change phenomenon has become more imminent in the present century than ever before, as indicated by the unabated rise in atmospheric temperature aberrations from local to regional scales. Our study focuses on the changes in mean air temperature (Tavg) in the parts of eastern Himalaya, representing Naga, Lusai and Khashi hills, extended over the regional boundaries of seven northeast Indian states. We observed statistically significant increase in annual Tavg, for the majority of ground meteorological stations in northeast India. Monthly values depict significant increase for Basar, Imphal and Gangtok in the majority of the months, followed by Umiam, Kolasib and Kailashahar. Despite the spatial variability, the overall range of increase in Tavg is 0.2 °C to 1.6 °C per decade across the study region. Significant rise in Tavg during the winter is experienced by five out of seven places. Change-point detection analysis revealed that Tavg values of Imphal experienced maximum number of shifts during the early to late 1990s, followed by Gangtok, Basar, Umiam and Kolasib. Shifts in Tavg during winter months are also most common and occurred during the late-1990s. The results may be used in modelling the impact of changing climate on the ecosystem and agriculture of north-east India.