Temporal variation and frequency dependence of ambient noise on Mars
from polarization analysis
Abstract
We applied a polarization analysis of InSight seismic data to estimate
the temporal variation and frequency dependence of the Martian ambient
noise field. Low-frequency (<1 Hz) P-waves show a diurnal
variation in their dominant back-azimuths that are apparently related to
wind and the direction of sunlight in a distant area. Low-frequency
Rayleigh waves (0.25–1 Hz) show diurnal variations and a dominant
back-azimuth related to the wind direction in a nearby area.
Low-frequency signals that are derived mainly from wind may be sensitive
to subsurface structure deeper than the lithological boundary derived
from an autocorrelation analysis. On the other hand, dominant
back-azimuths of high-frequency (>1 Hz) waves point toward
the InSight lander, especially in daytime, indicating that wind-induced
lander noise is dominant at high frequencies. These results point to the
presence of several ambient noise sources as well as geologic structure
at the landing site.