P058-02
Ground deformations due to atmospheric forcing at InSight landing site: effect of lateral variation of sub-surface properties and response to various atmospheric waves
Ground deformations due to atmospheric forcing at InSight landing site: effect of lateral variation of sub-surface properties and response to various atmospheric waves
Monday, 14 December 2020: 08:34
Virtual
Abstract:
Since InSight mission landed on the border of a hollow crater (on November 26th 2018), seismometer sensors and atmospheric pressure, wind and temperature sensors are recording continuously the atmospheric forcing and its subsequent ground deformations. Previous studies demonstrated how these signals can be used to infer the properties of convective vortices (Murdoch et al., 2020), the sub-surface mechanical properties (Lognonne et al., 2019; Kenda et al., 2020), the long period forcing by gravity waves (Spiga et al., 2018; Garcia et al., 2020) and even the infrasound signals below the noise level of pressure sensor (Martire et al., 2020).
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We will show in this presentation that three aspects of the pressure/ground deformation relation are not yet fully understood. First, the coherence between Pressure and seismometer signals, as well as the convective vortices signals, suggest a time shift between these two records larger than 1 second and varying between day and night.
Then, the compliance values obtained in the mHz range from atmospheric gravity wave signals recorded by the seismometer are much larger than the ones expected in this frequency range.
Finally, the horizontal compliance values varies significantly with azimuth, suggesting that lateral variations of sub-surface properties that can bias our estimates of atmospheric forcing sources.
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In a first part, we provide a detail analysis of the pressure sensor transfer function, in particular its group delay. We also cover other potential instrument effects that may play a role in the pressure/SEIS relations.
In a second part, we provide theoretical estimates of compliance for various one dimensional sub-surface models, and numerical simulations of atmospheric forcing in 3D sub-surface models of the hollow crater.
These results are analyzed to estimate the relative contributions of each mechanism, and to infer and correct the biases induced on our estimates of atmospheric forcing sources.
Estimates of the arrival azimuths of gravity waves at InSight location are provided and analyzed.
\newline
We will show in this presentation that three aspects of the pressure/ground deformation relation are not yet fully understood. First, the coherence between Pressure and seismometer signals, as well as the convective vortices signals, suggest a time shift between these two records larger than 1 second and varying between day and night.
Then, the compliance values obtained in the mHz range from atmospheric gravity wave signals recorded by the seismometer are much larger than the ones expected in this frequency range.
Finally, the horizontal compliance values varies significantly with azimuth, suggesting that lateral variations of sub-surface properties that can bias our estimates of atmospheric forcing sources.
\newline
In a first part, we provide a detail analysis of the pressure sensor transfer function, in particular its group delay. We also cover other potential instrument effects that may play a role in the pressure/SEIS relations.
In a second part, we provide theoretical estimates of compliance for various one dimensional sub-surface models, and numerical simulations of atmospheric forcing in 3D sub-surface models of the hollow crater.
These results are analyzed to estimate the relative contributions of each mechanism, and to infer and correct the biases induced on our estimates of atmospheric forcing sources.
Estimates of the arrival azimuths of gravity waves at InSight location are provided and analyzed.