关键词: 地空频率域电磁法, 激发极化效应, Cole-Cole模型, 视电阻率, 视极化率

Abstract: The ground-air frequency-domain electromagnetic (GAFDEM) method has broad application prospects in studying deep geological structures in complex terrains. However, current studies and applications mainly focus on ground resistivity imaging, with limited in-depth studies on the measurement of induced polarization effects. This paper aims to systematically investigate the influence of polarization effects on GAFDEM measurement results and proposes a method for simultaneous imaging of apparent resistivity and apparent polarizability. To this end,  based on Maxwell’s equations and the Cole-Cole model,a forward model of electric-source ground-air frequency-domain electromagnetic response considering polarization effect  is established.  The influence of parameters such as resistivity and polarization rate on the airborne magnetic field is analyzed, and a method for simultaneous calculation of apparent resistivity and apparent polarizability is proposed using Sobol sensitivity analysis and particle swarm optimization. Finally, simulation experiments are conducted to verify the effectiveness of this method in identifying low-resistivity, high-polarization targets. The results show that the apparent resistivity curves for all models exhibit a characteristic dip at the low-resistivity target layer, intuitively reflecting the low-resistivity properties of the target layer. Models including polarization effects display high values at the target layer, with the anomaly amplitude increasing as polarization rate rises. The zero-polarization model shows a relatively flat apparent polarization curve. Experimental results further indicate that both ground resistivity and polarizability significantly affect the amplitude of the airborne magnetic field, with low-resistivity, high-polarization anomalies generating significant magnetic field response anomalies. 

Key words: ground-air frequency-domain electromagnetic method, induced polarization effect, Cole-Cole model, apparent resistivity, apparent polarizability