Probing the Martian atmospheric boundary layer using impact-generated
seismo-acoustic signals
Abstract
The properties of the first kilometers of the Martian atmospheric
Planetary Boundary Layer have until now been measured by only a few
instruments and probes. InSight offers an opportunity to investigate
this region through seismoacoustics. On six occasions, its seismometers
recorded short low-frequency waveforms, with clear dispersion between
0.4 and 4Hz. These signals are the air-to-ground coupling of
impact-generated infrasound, which propagated in an low-altitude
atmospheric waveguide. Their group velocity depends on the structure of
effective sound speed in the boundary layer. Here, we conduct a Bayesian
inversion of effective sound speed up to 2000m altitude using the group
velocity measured for events S0981c, S0986c and S1034a. The inverted
effective sound speed profiles are in good agreement with estimates
provided by the Mars Climate Database. Differences between inverted and
modeled profiles can be attributed to a local wind variation in the
impact → station direction, of amplitude smaller than 2m/s.