CR 77:45-61 (2019)  -  DOI: https://doi.org/10.3354/cr01539

ABSTRACT: Bangladesh regularly faces various extreme events (floods, droughts, cyclones, and heat waves), but there is a knowledge gap between average climate and climate extremes over the country. The purpose of this study is to quantify the trends over Bangladesh for the period 1981-2010 using the extreme temperature and precipitation indices developed by the CCl/WCRP/JCOMM Expert Team on Climate Change Detection and Indices. We used precipitation and temperature data from 26 meteorological stations, calculated trends in the indices using Sen’s slope estimator, and tested significance using the non-parametric Mann-Kendall trend test. For the temperature indices, we found an overall increasing warming trend. Average annual maximum and minimum temperatures increased by 0.3 and 0.4°C decade^-1 respectively. A faster rise of both maximum and minimum temperature was found compared with previous studies. The frequency of warm days increased by 12 days decade^-1. The frequency of warm (cold) nights increased (decreased) by 7 (11) days decade^-1. The overall warming was accelerated at the end of the climatic period (2001-2010). Precipitation indices showed an overall decreasing trend, in contrast to other studies in this region. Trends in consecutive dry days (CDD) indicated a drying tendency at a rate of 10 days decade^-1. A decreasing rate of about 84 mm decade^-1 was observed in annual average total precipitation. Except for CDD, most of the precipitation trends were statistically not significant and spatially incoherent. Statistically significant change was observed in extreme temperature events, with a strong and consistent spatial pattern. Our results pave the way for further investigations into future changes using results from climate simulations.

KEY WORDS: Extreme indices · Expert Team on Climate Change Detection and Indices · ETCCDI · Bangladesh · Observed records · Climate change