The invention provides a low-frequency magnetotelluric data denoising method based on an over-complete dictionary and a
compressed sensing reconstruction algorithm. The method comprises the followingsteps of firstly, extracting a rough low-frequency effective
signal from a noisy magnetotelluric
time sequence by using mathematical
morphological filtering; then, using complementary set empirical mode
decomposition to smooth the rough low-frequency effective
signal so as to obtain an accurate low-frequency effective
signal, and acquiring a noisy
high frequency signal by subtracting the extractedlow frequency effective signal from the noisy magnetotelluric
time sequence; and finally, through designing a suitable over-complete dictionary, using the
compressed sensing reconstruction algorithmto carry out signal-
noise separation on the noisy
high frequency signal, and acquiring a de-
noise high-frequency effective signal; and acquiring a full
spectrum band magnetotelluric effective signal through adding the low-frequency effective signal and the high-frequency effective signal. In the invention, under the condition that the magnetotelluric effective signal is well reserved, a strong human
noise in low-frequency magnetotelluric data is removed, a signal-to-noise ratio of the magnetotelluric data is significantly increased, and an
apparent resistivity and a phase curve are improved.