Long-term trend analysis of climatic variables and reference evapotranspiration over different urban areas in Tunisia

Basma Latrech,Abdelhamid Boujelben,Boutheina M Douh,Lasram Asma,Hiba Ghazouani,Mansour Mohsen

doi:10.21472/bjbs.061218

Abstract

In this study, the trend analysis of annual climatic variables including Tmax, Tmin, Tmean, RHmean, WS and SR as well as FAO-56 PM ET0 were investigated in three locations in Tunisia during 1984-2007. The Mann-Kendall Test, the Sen's Slope Estimator and linear regression tests were used for the analysis. The obtained results showed a significant increasing trends (a < 0.001) and (a < 0.01) in annual Tmax, Tmin and Tmean at all the considered locations. However, Tmin increase faster than Tmax with a slope of magnitudes ranging between 0.057 to 0.1 oC year-1. For RHmean, a non-significant tendency of decrease was observed in Chott-Mariem station. However, significantly increasing trends were found for Kelibia and Tunis Carthage. Concerning the WS variable, a tendency of decrease is observed during the study period for all the stations. Nevertheless, the statistical analysis of decreasing tendency of wind speed varied from non-significant for Tunis Carthage to highly significant (a <= 0.001) at Chott-Mariem and Kelibia. Despite the highly significant upward trend of temperature, the temporal pattern of mean annual FAO56 PM-ET0, over the different stations, did not exhibit any significant trend except for Kelibia station.

Highlights

Over the last century, atmospheric concentration of CO2 has increased significantly which resulted in an increment by 0.74 °C of the average global temperature as compared with the preindustrial era (UNFCCC, 2007)
Trend analysis of long term time series of climatic variables is a fundamental task in studies on climate change detection that has received a greater attention from scientists
Significantly decreasing trends of wind speed series were observed for Kelibia and Chott-Mariem stations as a result of the rapid urbanization

Summary

Introduction

Atmospheric concentration of CO2 has increased significantly which resulted in an increment by 0.74 °C of the average global temperature as compared with the preindustrial era (UNFCCC, 2007). An increasing trend of urban area has been detected worldwide over the last 50 years which results in a phenomenon called “urban heat islands” where the average temperature within an urban area can be several degrees warmer than the surrounding, undeveloped countryside (Crawley, 2008). In this context, trends in climate change is considered as an indisputable environmental issues (Gocic and Trajkovic, 2014), that have been identified in individual parameters, such as temperature or precipitation, and in integrated parameters, like reference evapotranspiration (ET0) (Ma et al., 2017). They showed warming trend in annual Tmean, Tmax and Tmin at the majority of the stations

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Conclusion