Title: Recent variations average maximum and minimum air temperatures over Bangladesh

Abstract

In the present study, long-term monthly average maximum and mean minimum air temperatures were analyzed to evaluate recent variations in Bangladesh's climate. Seasonal and yearly values were calculated by averaging monthly data. According to the Bangladesh Meteorological Department, seasons have been categorized as follows, pre-monsoon: March–May; monsoon: June–September; post-monsoon: October– November; and winter: December–February. The study has evaluated the annual, seasonal, and monthly maximum and minimum air temperature time series for 34 sites in Bangladesh from 1981 to 2020. Sen's slope estimator, linear regression, and Mann-Kendall were the three statistical tests that were utilized in the investigation. A considerably increasing maximum air temperature trend was observed at 47% of stations during the pre-monsoon, 100% during the monsoon, 74% during the post-monsoon, and 24% during the winter season. Similarly, during the pre-monsoon, monsoon, post-monsoon, and winter seasons, it was revealed that minimum air temperatures were noticeably rising in 41, 91, 41, and 35% of stations, respectively. According to the linear regression technique, the significant increasing maximum air temperature trends at the Patuakhali and Mongla stations are 0.83°C/decade and 0.82°C/decade in February and October, respectively. The stations of Mongla (-0.58oC/ decade) and Sandwip (-0.63oC/decade), respectively, reported the highest time series value decreases for the monthly maximum and lowest air temperatures in January. This knowledge will be useful for generating adaption plans that will decrease the negative effects of climate change. Bangladesh must put into practice measures including vulnerability analyses, disaster management, enhanced structure design, institutional reform, and anti-extreme climate engineering in order to adapt to climate change.