南极中山与昭和站重力海潮负荷效应及背景噪声研究

利用南极中山站LCR-ET21重力仪器与昭和站GWR058仪器获得的重力潮汐观测资料,采用最新的三个全球海潮模型(Dtu10,Eot11A和HAM11A)研究了南极地区的海潮负荷效应和背景噪声.结果表明,由三个海潮模型计算的重力负荷均值改正后,中山站O_1和M_2振幅观测残差分别由13.83%和20.55%下降到5.32%和5.95%,昭和站O_1和M_2振幅观测残差分别由10.84%和21.52%下降到1.91%和3.40%,说明海潮负荷改正的有效性.利用加汉宁窗的FFT变换,获得了地震频段的地震噪声等级(SNM),其值分别为1.574(中山站)和1.289(昭和站).而在潮汐频段,中山站的背景噪声比昭和站高一个数量级,主要由不同观测仪器和台站局部环境所致.本文结果可为进一步利用南极重力资料研究局部环境和全球动力学问题提供有效参考.

The research of ocean tide loading effects on gravity and ambient noise at Zhongshan and Syowa station in Antarctic

By using tidal gravity observations obtained by LCR-ET21 gravimeter at Zhongshan station and GWR058 instrument at Syowa station in Antarctic, we have studied the ocean tide loading (OTL) effects with the 3 latest global ocean models (Dtu10,Eot11A,HAM11A) and ambient noise. The results show that the amplitude residuals of O₁ and M₂ decrease from 13.83% and 20.55% to 5.32% and 5.95% at Zhongshan station and decrease from 10.84% and 21.52% to 1.91% and 3.40% at Syowa station after the OTL correction on gravity with the average of 3 ocean tide models. This indicates the effectiveness of the OTL correction. Using FFT transformation with Hanning window, we obtain the Seismic Noise Magnitude (SNM) in seismic band, which values are 1.574 (Zhongshan) and 1.289 (Syowa), respectively. However, in tidal band, the ambient noises at Zhongshan station are one order higher than Syowa station, mainly caused by the different instruments and the local environment of the station. Our results can provide effective reference for further use of gravity data of the Antarctic to study the local environment and the global dynamics.