Climate change signals based on rainfall and temperature trends in Malawi

Abstract

The purpose of the study was to determine climate change signals using rainfall and temperature records. This was achieved by performing time series and trend analysis. Time series analysis was done using MATLAB software while trend analysis was done using student’s t-test. The student’s t-test was used to establish if there are significant changes in the rainfall and temperature trends in order to explain climate change scenario over Malawi. Spatial variability was achieved by creating maps using SURFER software. The data was obtained from Department of Climate Change and Meteorological Services (DCCMS) of Malawi. Daily rainfall datasets and monthly datasets of maximum and mean minimum temperatures were obtained. Arithmetic mean method was used to estimate missing values. Outlier values were detected by physical checking and by plotting time series graphs. The results depicted a tendency towards decrease in seasonal and annual rainfall over most of the stations in the country. The decrease was not very significant. However, some eight stations showed an increasing trend in seasonal rainfall that was not significant. Five other stations showed an increasing trend in annual rainfall that was also not significant. On the other hand, in the analysis of temperature most stations depicted a tendency towards increase in maximum and minimum temperatures during winter and summer. The increasing trend was significant for most of the stations except for few stations such as Karonga, Dedza, Ngabu and Nkhatabay that showed a decreasing trend in minimum temperatures during winter and summer. Therefore, the results indicate that rainfall is decreasing over many locations while temperatures are becoming relatively warmer than they used to be. This observation suggests possible indications of a changing climate.