About surface temperature and their shifts in the Free State Province, South Africa (1960-2013)

The study analysed the temperature variability in the Free State Province, South Africa between 1960 and 2013. The three parameters considered were minimum temperature (Tmin), maximum temperature (Tmax) and diurnal temperature range (DTR) during the summer agricultural season spanning from October to March. Spatial interpolation of temperature characteristics was done using ArcMap V.10.2. Results show that the late summer subseason (January-March) generally experiences warmer temperatures than the early summer subseason (October-December). A significant shift towards warmer temperatures was detected for Tmax during the October-December subseason around 2003 and around 1983 for the January-March subseason for Tmin. The OND Tmax shift coincides with that in cloud cover, suggesting that the reduced cloud cover could have contributed to the Tmax shift. It is found that the significance of temperature change is stronger towards the north and northwestern regions of the province.