Abstract:

As an important technology for processing and interpreting gravity data, downward continuation has attracted the attention of researchers because of its ill-posedness. The space domain continuation method generally has high continuation accuracy, but the computational complexity is usually large. In this paper, firstly, according to the characteristics of gravity anomaly data and the idea of image restoration, an equivalent mathematical model of gravity downward continuation is proposed. Then, based on the block-Toeplitz Toeplitz-block (BTTB) structure of the coefficient matrix, we propose a space-wavenumber mixed domain downward continuation iterative method with nonnegative constraints. The method overcomes the disadvantage of large computational complexity in space domain continuation and has high computational efficiency. The comparison experiments of theoretical gravity model and real anomaly data show that the gravity field downward continuation method proposed in this paper has high downward continuation accuracy and stability, and has good convergence.

Key words: gravity, nonnegative constraints, downward continuation, steepest descent method, BTTB matrix