Trends of the observed temperature and its variations in the Tamil Nadu State of India

In this study, the trends of the annual and seasonal temperature and its variations are explored in the Tamil Nadu State of India. In order to find the trend direction and the magnitude of change across the state during 1969-2016, the mean maximum temperature (MMaxT), mean minimum temperature (MMinT), and mean annual temperature (MAT) of 17 climatological stations are analyzed. Evidently, the increasing trends in MMaxT, MMinT, and MAT are observed at the majority of the stations. Approximately 82% of the total stations have shown a significant positive trend in MAT and MMaxT at the 95% confidence level. The MAT has increased up to 1.4 degrees C with a variation in the rate of change from 0.01 to 0.29 degrees C per decade. MMaxT has shown a significant increase with a variation in the rate of change from 0.01 to 0.54 degrees C per decade for the last 47years. However, MMinT has shown an increasing trend in 13 stations and a decreasing trend in 4 stations with a variation in the rate of change from -0.05 to 0.31 degrees C per decade. In the recent decades, the majority of the stations have experienced high warm and the year 2016 is observed to be the warmest year. Based on a spatial scale, temperature differences have been observed between coastal and inland stations. The majority of the coastal stations have shown a high increase in MMaxT as compared to the inland and hill stations. On the contrary, the inland stations have shown a high increase in MMinT as compared to the coastal stations. A more definite increasing trend is observed during the winter and postmonsoon seasons followed by the monsoon season.