The 2019-2020 geomagnetic jerk as observed by southern African magnetic observatories.

Rapid secular variation pulses in the Earth’s geomagnetic field have been identified during the last decade. In particular the 2019-2020 event is the latest in a series of rapid secular variation events observed at the Earth’s surface which are thought to be the result of rapid oscillations at the core surface approximately at a depth of 3000 km. In Southern Africa the 2019-2020 pulse has been analysed using data from 4 observatories located at Hermanus, Hartebeesthoek, Keetmanshoop and Tsumeb, and found that the 2019-2020 event occurred with varying strengths in the different components at a particular observatory, while different observatories in the region showed strong individual characteristics. These rapid changes in the secular variation patterns at individual magnetic observatories in this study can also be influenced by the South Atlantic Anomaly (SAA) where the geomagnetic field has been diminishing at a very rapid rate over the past 400 years in comparison to regions at similar latitudes around the globe. Results will be compared to the global CHAOS field model derived from ground and SWARM satellite data.