Li Hang, Chen Xiaodong, Zhang Miaomiao, Niu Xiaowei, Xu Jianqiao, Sun Heping
History, Culture and Tourism School, Fuyang Normal University, Fuyang 236037, China.
State Key Laboratory of Geodesy and Earth's Dynamics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430077, China.
Sensors (Basel). 2024 Nov 22;24(23):7446. doi: 10.3390/s24237446.
The noise level of gravity stations is an important indicator for measuring the operating status of a station and is a prerequisite for evaluating whether the station's observations can be used to extract weak geodynamic signals. With the continuous expansion of areas of human activity, gravity stations originally located in the wild may become increasingly closer to cities. Whether their noise levels change is an important issue that is worthy of attention. Based on power spectrum analyses and probability density function methods, the noise level of the superconducting gravimeter (SG) at Jiufeng station in Wuhan in the seismic frequency band of 0.001-0.04 Hz was calculated, and its time-varying characteristics were analyzed. The noise level of Jiufeng station did not change significantly before and after the lockdown of Wuhan due to the COVID-19 epidemic in 2020. No significant changes in the noise level were found before and after the official operation of Wuhan Metro Line 19 at the end of 2023. From October 2016 to April 2017, the noise level showed an abnormal trend of suddenly rapidly rising and then slowly declining, which was found to be caused by a tilt problem in the gravity sensor. Overall, in the seismic frequency band of 0.001-0.04 Hz, the noise level at Jiufeng station showed seasonal variation characteristics, and the noise was stronger in winter than in summer, which is consistent with the characteristics of Earth's hum. Since January 2022, the noise level has shown an increasing trend year by year. The results of this study can provide an important reference for the operation of gravity stations and the extraction of weak geodynamic signals.
重力台站的噪声水平是衡量台站运行状态的重要指标，也是评估台站观测数据能否用于提取微弱地球动力学信号的前提条件。随着人类活动区域的不断扩大，原本位于野外的重力台站可能会越来越靠近城市。其噪声水平是否发生变化是一个值得关注的重要问题。基于功率谱分析和概率密度函数方法，计算了武汉九峰台站超导重力仪（SG）在0.001-0.04Hz地震频段的噪声水平，并分析了其随时间变化的特征。2020年因新冠疫情武汉封城前后，九峰台站的噪声水平没有明显变化。2023年底武汉地铁19号线正式运营前后，噪声水平也没有发现明显变化。2016年10月至2017年4月，噪声水平出现突然快速上升然后缓慢下降的异常趋势，经查明是重力传感器的倾斜问题所致。总体而言，在0.001-0.04Hz地震频段，九峰台站噪声水平呈现季节性变化特征，冬季噪声比夏季更强，这与地球嗡鸣声的特征一致。自2022年1月以来，噪声水平呈逐年上升趋势。本研究结果可为重力台站的运行及微弱地球动力学信号的提取提供重要参考。
