Long-Term Trend of the All-Bangladesh Summer Monsoon Rainfall, and its Association with the ENSO Index

Abstract

Rainfall data for the summer monsoon season (May through October) at 15 weather stations in Bangladesh, for the 60 year period from 1951 to 2010, and ENSO Index data coinciding with the summer monsoon season for the corresponding years were analyzed in order to determine the long-term trends of summer monsoon rainfall and ENSO Index, and association between them. In this study, summer monsoon rainfall in Bangladesh has been expressed as “All-Bangladesh” summer monsoon rainfall, which is an aggregate of the average rainfall at 15 weather stations for the months of June through October, in each year of the 1951-2010 period. Results indicate (a) a very slow increasing trend of All-Bangladesh summer monsoon rainfall, at a rate of 0.2073 mm per year over the 60-year period from 1951 to 2010, (b) a very slow decreasing rate of ENSO Index at a rate of –0.027 per year over the same period, and (c) there is no relationship between All-Bangladesh summer monsoon rainfall and ENSO Index during the same period.

Keywords: All-Bangladesh summer monsoon rainfall; summer monsoon rainfall trend; ENSO Index trend; association between All-Bangladesh summer monsoon rainfall and ENSO Index).