Changes in Temperature Extremes over Malawi during 1961 to 2015

Abstract

Changes in temperature and its extremes have widely been among key indicators in the global climate change discourse. In this study, we analysed the spatial and temporal trends of temperature extremes over Malawi in Southern Africa during 1961 to 2015. The analysis was based on observed daily maximum and minimum temperatures (T_max and T_mean) from 25 stations across the country. We derived 17 extreme temperature indices based on the WMO/CLIVAR Expert Team on Climate Change Detection and Indices (ETCCDI). These indices were analysed for significance of trend using the non-parametric Mann-Kendal test at α = 0.05 while their slopes were quantified using linear regression. The results suggest a countrywide warming pattern, with statistically significant increases in warming indices: SU25 at 7.56 days/decade; TR20 at 17.81 days/decade; Tmin at 0.46 ^oC/decade; TXx at 2.72 ^oC/decade; TNx at 2.20 ^oC/decade; TXn at 0.84 ^oC/decade; TN90p at 5.17 days /decade,; TX90p at 5.11 days/decade; and WSDI at 14.26 days/decade. In addition, the countrywide pattern suggest significant decreases in cold spell indices: CSDI at -2.17 days/decade, TN10p at -3.53 days/decade at TX10p at -30.40 days/decade. No significant changes were found in T_max, TNn and DTR. The lack of trends in the DTR and TNn, coupled with the significant trends in T_min and TNx suggest that the T_min increased more than the T_max across the country. The spatial pattern of the warming over Malawi is typical of regions experiencing considerable deforestation and urbanization.