International Journal of Environmental Sciences

Volume 2 Issue 3 2012           Pages: 1161- 1179

Variability and Trends of Temperature and Rainfall in Bangladesh

Author Information:

Wahiduzzaman, Md- Department of Environmental Sciences, Wageningen University and Research Centre, The Netherlands

This paper analyzes the variability and trends of temperature and rainfall in Bangladesh. The data of temperature and rainfall for 30 selected rain gauge stations of Bangladesh have been used over a period of 57 years (1948-2004) collected from Bangladesh Meteorological Department (BMD). The major findings of the study are that distribution of maximum temperature follows bimodal pattern with primary peak in April and the second one in September. The temperature decreases by about 20C during the monsoon season and the minimum temperature has the maximum in August, but has flat characteristics during the monsoon season. The winter has the maximum range of diurnal variation, which is 10-120C and the diurnal range is low during the monsoon season which is around 5-60C. The study of the spatial variability of temperature shows that in the winter the south has higher temperature than the north. In the summer, the western and central western Bangladesh appears warmest zone and is the drought prone area of the country. The time series analysis of annual country mean minimum and maximum temperature shows strong inter-annual fluctuations in the time scales around 2-3 and 4-7 years. In case of rainfall, the mean monthly rainfall of Bangladesh shows a unimodal pattern throughout the year with highest in July whereas lowest in January. Most of the rainfall occurs in the monsoon season. The coefficient of variation is high in the winter and low in the monsoon season. Summer monsoon rainfall widely varies over the geographical areas with lowest in central-western part conversely highest in southeastern part with moderate in northeastern part of the country. The short term variability of the scale 2-4 years is highly dominant. The decadal scale variation with time period around 10-11 years and 14-16 years are found to be prominent in the filtered series.

Keywords : Bimodal Pattern, Fluctuation, Summer Monsoon, and Unimodal Pattern

DOI: 10.6088/ijes.00202030005

© 2012 Copyright Wahiduzzaman, Md, licensee IPA.This is an open access article distributed under the Creative Commons Attribution License (2.0) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The electronic version of the article can be downloaded below.

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