Investigation of ambient noise source in North China array
华北科学探测台阵背景噪声特征分析

Noise Cross-Correlation Function (NCF) is obtained by processing one-year ambient noise observed at over 180 broad-band stations from North China Array. All available three-component time series are used to extract the Rayleigh and Love waves. The Signal-to-Noise Ratio (SNR) at different periods and the azimuth distribution of the inter-station pairs with high SNR are discussed. The azimuth distributions of the ambient noise source are investigated by analyzing the beamforming output. Although seasonal variations are observed from the beamforming output, the source distribution at 10~32 s is almost uniformly distributed in all directions, which allows us to perform the following detailed tomography safely.