Rainfall and Temperature Scenario for Bangladesh

A regional climate model named Providing REgional Climates for Impacts Studies (PRECIS) adapted in generating rainfall scenarios for the SAARC (South Asian Association for Regional Cooperation) region. At first, PRECIS generated rainfall scenario is calibrated with ground-based observed rainfall during baseline period (1961-1990) in Bangladesh. The regression coefficients obtained through calibration are utilized for validation of PRECIS simulated rainfall during 2000-2006. PRECIS overestimated rainfall by 12.37%, 1.58%, 10.81%, 4.79 and 13.18% in 2000, 2002, 2003, 2005 and 2006 respectively. It underestimated by 0.64% and 10.84% in 2001 and 2004 respectively. On an average, PRECIS overestimated about 4.47% of surface rainfall. Better performance of PRECIS through validation encourages employing it in rainfall forecasting for Bangladesh. In the second step, rainfall and temperature forecast for Bangladesh is experimentally obtained for 2010-2020. This work discloses that the PRECIS simulated rainfall and temperature are not directly useful in application purposes. However, after performing calibration, acceptable result is obtained in estimating annual rainfall in Bangladesh with correlation coefficient is 0.90. Change of rainfall is forecasted from -0.99% (in 2013) to 5.3% (2018) for Bangladesh during 2010 2020.