Time-domain inversion employs frequencies from a finite frequency-band wavelet to propagate seismic waves via a numerical approach. However, the classical time-domain FWI has been confined by the magnitude distribution of each frequency in a wavelet, resulting in an apparent “wavelet effect” at contrastive boundaries of structures in inversion results. To solve this problem, we innovatively propose a time-frequency domain FWI using a normalized source (TFFWI). In our method, we use a series of frequencies with accurate phase information but normalized amplitude as a new source in the time domain to achieve the spectrum whitening function. Accordingly, the virtual source is computed by summing all of the single-frequency misfits. Based on the adjoint method, the gradients corresponding to model parameters are calculated via frequency-domain gradient formulas, where the phase-sensitive detection (PSD) method is selected to achieve effective wavefield decoupling. The numerical examples demonstrate the advantage of our method.

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