自2011年观测以来,陕西宁强台洞体应变的高频气压效应甚为显著,但其频率依存性至今尚不明晰。为此,本文尝试采用相干函数和传递函数等方法,对该台2019年1月1日—4月2日的洞体应变和气压数据进行了系统诊断。结果表明,在8～40cpd频段内,洞体应变对气压具有较强的频率依赖性,即气压系数和相移均会随频率的变化而呈现非线性变化,其中,最大气压系数为7.80×10^-9/hPa,相位超前可达108.27°,且NS和EW分量的气压响应有所差异。上述结果将有助于该台高频噪声的物理溯源,同时还能为高频气压效应的分频段改正等提供量化依据。

The extensometric data observed at Geodynamic Observatory Ningqiang are strongly disturbed by barometric pressure variations in the high-frequency band since 2011. Although this phenonmenon has been observed for many years,the frequency-dependent barometric responses of extensometers are still not well understood. For this reason,we systematically analyze the coherences and transfer functions of tunnel strain changes associated with barometric pressure for Ningqiang observatory,respectively. In the data analysis,the 92-d-long data set of tunnel strain and barometric pressure data from 1st January to 2nd April 2019 are utilized. The results show that the atmospheric response of Ningqiang observatory obviously depends on frequency in the high-frequency range(8～40 cpd),and the barometric pressure coefficient and the phase advance can reach up to 7.80×10^-9/hPa and 108.27°,respectively. Besides,the responses of NS and EW components in the extensometers are slightly different. In summary,our work not only provides a useful method for frequency-dependent pressure correction in the high-frequency band,but also offers profound insights to study the mechanism of the pressure-induced noise from extensometric records.

P315

国家自然科学基金(U20A2095)、地震科技星火计划(XH20056Y)共同资助