1-D inversion of frequency-domain airborne electromagnetic data using the open-source aempy toolbox

Abstract

Over the past decade, Geological Survey Ireland has acquired, and continues to acquire, frequency and time-domain airborne electromagnetic data as part of the Tellus project. While the project advances towards national coverage, we have developed an open-source and freely available pre-inversion processing and one-dimensional inverse modelling toolbox, aempy, for numerical modelling of the existing and future electromagnetic data sets. aempy is a flexible tool facilitating the quantitative interpretation and optimal use of the data sets by the broader scientific community, supporting the ethos and intent in the free public release of the Tellus airborne data sets. Coded in Python, the toolbox is freely and readily adaptable for specific educational and research objectives and for application to data acquired using other electromagnetic systems. The inversion algorithms in the toolbox are currently implemented in 1-D, assuming that the Earth is horizontally stratified and has laterally-constant layer model parameters, e.g., conductivity and thickness. In its current state, modules and functions of aempy work on processed frequency-domain airborne electromagnetic data. In this paper, we introduce the concept, structure and capacities of aempy and present model results derived from the use of different filtering and inversion techniques implemented in the toolbox, as well as an analysis of the influence of the flight altitude parameter on resulting subsurface inversion models.