Impact of atmospheric noise on observing the slichter mode

Abstract

Atmospheric pressure fluctuations can result in long-period noise (T > 10 s) in gravity observations, and it is crucial to remove the atmospheric pressure effect for observing weak dynamic signals using superconducting gravimeters. This paper focuses on analyzing the impact of the atmospheric pressure on observing the Slichter mode signal. We analyze the effect of local atmospheric pressure fluctuations on gravity observations, yielding a correlation of over 90 % between the atmospheric pressure and gravity in the Slichter mode band (0.04–0.09 mHz). To better remove the atmospheric pressure effect on observing the Slichter mode, we use coherence analysis methods and refer to the Slichter mode reference degenerate frequency (0.0502 mHz) obtained by other researchers to compute the atmospheric admittance in the frequency domain. Taking the MW9.1 Tohoku earthquake that occurred in Japan on March 11, 2011, as an example, we analyze the noise level in the Slichter mode band after atmospheric pressure correction using gravity and atmospheric pressure data from superconducting gravimeter (SG) stations with simultaneous sampling at the same location. The results show that the coherence analysis method for calculating frequency domain admittance significantly affects correcting pressure noise, but detecting Slichter mode remains challenging. The noise level in the gravity is still much higher than the Slichter mode signal level. Other noise signals, such as ocean tidal noise and hydrological effect, may also affect observations of the Slichter mode. Future research needs to further analyze the effects of these types of noise.