Annual and Seasonal Trends in Extreme Temperature Events During 1981 to 2019 in Dry Zone, Sri Lanka

Purpose: Many parts of Sri Lanka are vulnerable to extreme climatic events, which are stressful in numerous ways, especially the dry zone that is highly responsible for agricultural activities. Paddy, the major crop cultivated throughout the dry zone, is highly sensitive to temperature variations. Thus, it badly affects production so the food security in the country will be negatively impacted. Therefore, studies on temperature extremes and their trends are highly important to mitigate the impact. The objective of this study is to identify the annual and seasonal trends of temperature extremes in the dry zone of Sri Lanka using the daily maximum and minimum temperature data from 1981 to 2019.
Research Method: To represent the entire dry zone, 10 locations were selected. As described by the Expert Team on Climate Change Detection and Indices (ETCCDI) 17 extreme temperature indices were selected and another appropriate three were defined by authors as suitable. Temperature extremes were analyzed by RClimDex software package, and MS Excel and the Mann-Kendal test and regression were done to identify trends.
Findings: Accordingly, 50% of the selected locations showed a significant (p<0.05) rise in daytime temperatures. Similarly, in general, significant positive trends were detected for nighttime temperature annually and seasonally. The increment in daytime temperature was with a lower magnitude than the positive trend in nighttime temperature. A general decreasing trend was detected in the Diurnal Temperature Range and it was mainly driven by the increasing trend of the nighttime temperature across the dry zone.
Originality/ Value: In the dry zone, there were dynamic trends with significant patterns as both rising and falling trends were detected in temperature indices during this study.