Temperature trends in Sri Lanka

Abstract

Being a small island and substantially influenced by the temperamental monsoon, Sri Lanka is potentially vulnerable to heat waves. The impacts of such temperature are becoming adverse in the view of the apparent increase in historical trends which is generally felt as heat exhaustion. Various numerical studies have confirmed this temperature rise and the current situation is becoming serious compared to previous decades. The trend detection in this study was executed using parametric & non-parametric regressions. In particular, the statistical significance of the slope parameter of fitted linear models was tested using standard ordinary least square method and the non-parametric methods such as the Mann-Kendall and Sen-Theil tests. For this statistical analysis, daily temperature records from 1961-2014 was used for the twenty stations geographically distributed throughout the island. Baseline data show a significantly increasing trend in maximum temperature over the decades in many districts of Sri Lanka and such increase is felt as heat strike in most of the districts. The all-time highest temperature was observed in Anuradhapura and Vavuniya districts, which are the dry zone landlocked region of Sri Lanka. The observed heat exhaustion over Sri Lanka was prominent, during the months of March and April, in which the sun directly positions over the equator line where the island is located. Though the temperature rise due to climate change may be the reason for the heat wave, lack of strong seasonal winds and scanty rainfall may be the reasons for the recent heat waves in Sri Lanka.