Analysis of Air Temperature Trends as a Climate Change Indicator for Alexandria (Egypt)

Abstract

This work provides the results of the analyzed long-term trends for three air temperature categories, namely: average (Tavg), maximum (Tmax) and minimum (Tmin) on monthly, annual and seasonal bases for Alexandria. The aim was to examine possible climate changes in this famous City based on the results obtained from the analyzed trends. The study was based on examining (1) linear regression approaches, (2) trend magnitudes, (3) Mann-Kendall trend test and (4) extreme air temperature events. The air temperature data from Alexandria International Airport station were used over a period of 65 years (1957-2021). For all analyzed time series, the results showed statistically significant positive trends. The exception was for the monthly mean Tmax during January, February and December (negative trends), and March (No trend). The H1 hypothesis prevails for the three temperature categories, on different basis. Over the period of investigation, both the annual mean Tavg and Tmin rose at a rate of +0.02 °C/yr, while annual mean Tmax rose at a rate of + 0.008°C/ yr. In winter, the annual mean Tavg and Tmin had increasing trends at a rate of +0.02 °C/yr. The winter Tmax had a feeble increasing trend (almost constant), at a rate of only +0.0003 °C/yr. In summer, the three air temperature categories increased at a rate of +0.02 °C/yr, each. Extreme air temperature times were specified in this study on all bases for the three temperature categories. The findings of this study are thought to be a reliable indicator of the presence of climate change in Alexandria. Keywords: Alexandria, air temperature, climate change, trend analysis, extremes