CR prepress abstract  -  DOI:

Observed trends in climate extremes over Bangladesh from 1981 to 2010

Md. Jamal Uddin Khan, AKM Saiful Islam*, Mohan Kumar Das, Khaled Mohammed, Sujit Kumar Bala, GM Tarekul Islam


ABSTRACT: A set of extreme indices developed by the joint CCI/WCRP/JCOMM Expert Team on Climate Change Detection and Indices (ETCCDI) has been calculated by standard tools using the precipitation and temperature data from 26 selected meteorological stations over Bangladesh. The trends in the indices have been calculated using Sen's slope estimator and significance has been tested using non-parametric Mann-Kendall trend test. The period of analysis is from 1981 to 2010. An overall increasing warming trend has been found for the temperature indices. The average annual maximum and minimum temperatures have increased 0.3 and 0.4°C decade–1 respectively. A faster rise of both the maximum and minimum temperature of this region was found compared with previous studies. The frequency of warm days has increased by 12 d decade–1. Similarly, the frequency of warm (cold) nights has increased (decreased) by 7 (11) d decade–1. The overall warming was accelerated at the end of the climatic period (2001–2010). Precipitation indices have registered an overall decreasing trend over Bangladesh which is in contrast to other studies in this region. Trends in consecutive dry days (CDD) indicating a drying tendency at a rate of 10 d decade–1. A decreasing rate of about 84 mm decade–1 has been observed in annual average total precipitation. However, except for CDD most of the precipitation trends are statistically not significant and spatially incoherent. On the other hand, statistically significant change is observed in extreme temperature events with a strong and consistent spatial pattern.