A case study on more recent heat wave occurred in South Africa, based on background weather synoptic and dynamic characteristics analysis

Abstract

This study investigates the characteristics of the more recent heat wave episode in South Africa during January 2023. The evaluation of several meteorological parameters using different reanalysis models and observational datasets have demonstrated that the domination of the anticyclonic pattern over the study area associated with a omega-blocking high. The dominant subtropical Botswana subtropical high along with the low-level omega blocking high pressure over South Africa is one of the main factors for the abnormally hot weather event. The upper-level anomaly wind analysis illustrates the weakening of the zonal wind accompanied by the Rossby waves meridionally stretching. Also, this is correlated to abnormal both tropical easterly and southern westerly jets meandering around an omega-blocking pattern weather system over South Africa which causes warm air mass trapping over the study region. The outcome model results prove the anomalies of the surface higher temperature happened close to the center of the blocking high, where an intensified southward shift of the easterly tropical jet along with the northward shift (jet entrance) of an intensified westerly jet formed two strong cores creating confluent. This research also shows that the January heat wave is demonstrated by an anomalous upper tropospheric anticyclonic inflow (southern hemisphere) causing the strong subsidence, resulting in the surface temperature increase. In comparison with the heat wave event in January 2016, the current study displays the high impact of the internal and local dynamical processes. Also, the current case study addressed in drier condition with less health risk than the previous case study noticed in 2016.