Recent changes in temperature and rainfall trends and variability over Bangladesh

This paper presents results of the baseline climate change analysis of Bangladesh Delta Plan 2100 (BDP) project based on the available monthly and daily data of temperature and rainfall for 34 stations of Bangladesh covering the maximum period of 1948-2011 (64 years) or as available. Data was analyzed to assess trends and variability in seasonal and annual
temperature and rainfall across the country. Most stations showed increasing trends for both temperature and rainfall with a few exceptions.The exceptions are probably related with local land-use factors. Rainfall especially increased (20%) during the pre-monsoon period from March till May. Rainfall also increased slightly during the monsoon, however, during the post monsoon and dry season rainfall has hardly changed over the last 60 years. The analysis of the daily rainfall shows that the number of rain days has increased. The trends of frequency of rainfall with daily rainfall higher than 20 mm and 50 mm have been estimated for the dry and wet period of the year respectively as well as for individual months. While the seasonal and annual rainfall is found to increase, the intensity has not been found to increase much. This depicts that the increase of rain days is the main factor responsible for the increase of rainfall. Besides, the frequency of events with consecutive 3 or more days of rainfall and the frequency of events of consecutive 10 or more number of dry days have been investigated for selected areas and discussed.