Modelling the airborne Induced Polarization effects at continental scale: the Tempest case study in the AusEM project

Tempest is a very successful AEM system, used over the last 2 decades for mapping changes in subsurface conductivity from tenement to regional scales (Lane et al, 2000). It delivers B field 100 % duty cycle data for X and Z components. It has been the subject of extensive research and development from both internal and third parties (e.g., Mulè and Smiarowski, 2013; Brodie and Ley Cooper, 2019). This paper focuses on a rather novel aspect: its sensitivity to IP effects and the relevance of modelling IP in its data. Airborne IP (AIP) modelling has been researched extensively over recent years, mainly in Helicopter Time Domain EM data. Both the industry and the academic community (Oldenburg and Kang, 2015, Macnae, 2016, Viezzoli et al., 2017, Cox et al., 2022,) have come to accept AIP as an important part of HTEM data. We now wish to take a similar approach for the Tempest Fixed-wing Time Domain EM (FTEM) system. We focus on the Tempest system given its large application for continental scale mapping, such as for the AusEM project in Australia. Here, this fixed-wing system is used to map the ground resistivity of the entire Australian continent and has already covered an amount of 2millions of flown line-kilometres. In this scenario, being able to extract the ground chargeability from the AEM data would add a high-impact extra layer of information to the continental mapping for mineral purposes.