Analysis of long term spatio- temporal trend of rainfall in Tamil Nadu between 1981-2020

Increased anthropogenic activity in recent decades has resulted in major global climate change. This paper mainly focuses on the assessment of changes occurring in the spatio -temporal distribution of rainfall with 40-years database of monthly precipitation for Seasonal Precipitation Concentration Index (SPCI) and trends in Tamil Nadu. The hydro-meteorological time series rainfall data over a period of 40 years (1981–2020) was collected from Tamil Nadu Agricultural University and India Meteorological Department and subsequently analysed using various statistical methods for Tamil Nadu. The SPCI was analysed for both southwest and northeast monsoon. SPCI values ( 10) showed that more weather extremes were observed during northeast monsoon. Mann–Kendall, non-parametric test was done using trend software for both the monsoon. During southwest, significant increasing trend in rainfall was observed at Coimbatore (1.8mm/season/year), Erode (2.1mm/season/year), Perambular (2.1mm/season/year), Theni(2.0mm/season/year) and Tirunelveli (2.4 mm/season/year) while significant decreasing trend in rainfall was observed at Namakkal(2.5 mm/season/year). During northeast, significant increasing trend in rainfall was observed Kancheepuram (2.4 mm/season/year), Tutucorin(2.6 mm/season/year) and Villupuram(2.0 mm/season/year).