Five Decadal Trends in Averages and Extremes of Rainfall and Temperature in Sri Lanka

Abstract

In this study, we used a comprehensive set of statistical metrics to investigate the historical trends in averages and extremes of rainfall and temperature in Sri Lanka. The data consist of 55 years (1961–2015) of daily rainfall, maximum temperature (Tmax), and minimum temperature (Tmin) records from 20 stations scattered throughout Sri Lanka. The linear trends were analyzed using the nonparametric Mann–Kendall test and Sen–Theil regression. The prewhitening method was first used to remove autocorrelation from the time series, and the modified seasonal Mann–Kendall test was then applied for the seasonal data. The results show that, during May, 15% of the stations showed a significant decrease in wet days, which may be due to the delayed southwest monsoon (SWM) to Sri Lanka. A remarkable increase in the annual average temperature of Tmin and Tmax was observed as 70% and 55% of the stations, respectively. For the entire period, 80% of the stations demonstrated statistically significant increases of Tmin during June and July. The daily temperature range (DTR) exhibited a widespread increase at the stations located within the southwestern coast region of Sri Lanka. Although changes in global climate, teleconnections, and local deforestation in recent decades at least partially influence the trends observed in Sri Lanka, a formal trend attribution study should be conducted.

Trend and Variability Analysis of Rainfall and Extreme Temperatures in Burundi

“…In Benin, a study on analysis of trends in the variability of monthly means minimum and maximum temperature and relative humidity in Benin city revealed a positive increase trend of temperature while humidity shows a decreasing trend with a negative slope [8]. Others studies on trends and variability of rainfall and extreme temperature time series have been carried out in Botswana [9] and Sri Lanka [10]. The results revealed a general decreasing trend in rainfall and warming trends in both maximum and minimum temperature.…”

Climate Change and Extreme Events in WL1a Agro-ecological Zone of Sri Lanka: Implications on Coconut Production

“…Marambe et al (2013), Premalal andPunyawardena (2013), De Costa (2008) and Ministry of Environment Sri Lanka, (2011), who examined climatic conditions in Sri Lanka, revealed an increase in both minimum and maximum ambient temperature in most districts and a decrease of rainy days prolonging the dry spells. The variability of seasonal rainfall of Sri Lanka has increased in recent decades according to Nissanka et al (2011) and there is a warming trend in temperature with occurrence of more frequent droughts according to Premalal and Punyawardena (2013) and Naveendrakumar et al (2018). An increase in the number of consecutive dry days and a decrease in the number of consecutive wet days are also observed (Ratnayake and Herath, 2005;Premalal, 2009).…”

Spatial Variability of Rainfall Trends in Sri Lanka from 1989 to 2019 as an Indication of Climate Change

“…Moreover, rainfall analysis provides essential information for decision-makers on activities such as water resource management, development, policy planning, and disaster preparedness [23]. The same scenario also reported that there has been a significant change in rainfall trend in Sri Lanka over the last few decades [24]. Due to the geographical context of Sri Lanka, the Indian Ocean (IO) monsoon system influences the systematic migration of rainfall over the country's various geographical areas throughout the year [25].…”

“…Although many studies have been conducted to understand the rainfall trends in Sri Lanka, most of those studies focused only on data gathered from a limited number of rainfall stations [21,24,43]. Therefore, spatial variability was not captured in those studies.…”