Temperature and precipitation changes in the north-east India and their future projections

摘要

North East India (NEI), which comprise eight states, is very vulnerable to global changes and yet it was least studied so far. In this study, the present-day climatic conditions prevailing in NEI are examined based on actual observations at the meteorological stations of India Meteorological Department (IMD) in the region and on the gridded data. Further, Regional Climate Model version 3 (RegCM3) is also used to examine the projected changes in climatic parameters of temperature and precipitation in NEI under the IPCC A1B scenario. First of all, the model simulations in the present era spanning 1971-2005 are compared with the IMD gridded datasets to validate the model performance. It is found that RegCM3 is able to simulate the trends in annual mean temperature for the period 1971-2005 correctly. However, there is overestimation of rainfall simulated by the model. Major parts of NEI show a wet bias in the model precipitation. The simulated annual mean temperatures for the region show a good correlation with the gridded temperature values. Based on the IMD gridded datasets, the extreme temperature events of daily maximum and minimum temperatures are also examined in this study. Results indicate that during the years 1971-2005, the occurrence of warm nights in summer months was more frequent than the warm days. The simulations to the future years indicate rise in the annual mean temperature as well as mean rainfall. Projections based on RegCM3 simulations further indicate more frequent warm events than the cold events.