STUDYING MARTIAN TURBULENCE USING HIGH FREQUENCY
PRESSURE FLUCTUATIONS OBSERVED BY INSIGHT AND
PERSEVERANCE
N. Murdoch1 (naomi.murdoch@isae-supaero.fr), A.E. Stott1, A. Spiga2, O. Temel3, A. Chatain4, T. Bertrand5, S. Maurice6, B. Chide7, C. Newman8, D. Banfield9, J. Pla-Garcia10, R. Garcia1, M. Gillier1, M. De La
Torre Juarez11, A. Chavez11, A. Munguira11, R. Hueso12, A. Sanchez Lavega12, G. Martinez13, L. Lange2, J.
Rodriguez-Manfredi10, R. Wiens14, P. Lognonné and D. Mimoun1
1

ISAE-SUPAERO, 10 ave E. Belin, 31400 Toulouse, France, 2LMD, Paris, France, 3Royal Observatory of
Belgium, Belgium, 4South West Research Institute, CO, USA, 5Paris Observatory, France, , 6IRAP, Toulouse,
France, 7LANL, NM, USA, 8Aeolis Research, Chandler, AZ, USA, 9Cornell University, NY, USA, 10Centro
de Astrobiología (CSIC- INTA), Madrid, Spain, 11JPL /California Institute of Technology, Pasadena, CA,
USA., 12Universidad del País Vasco (UPV/EHU), Bilbao, Spain, 13Lunar and Planetary Institute, Houston, TX,
USA, 14Purdue, IN, USA, 15IPGP, Paris, France.
Introduction: Different types of turbulent regimes
exist in the atmosphere, particularly in the planetary
boundary layer (PBL), the lowermost part of the
atmosphere. This is the part of the atmosphere that
is in contact with the planetary surface and is of
critical importance for the mixing of heat, momentum, dust, and a variety of chemical species between the surface and atmospheric reservoirs [1].
Given that all Mars landers have to pass through
and operate in the Martian PBL, understanding this
part of the Martian environment is also extremely
important for the in-situ exploration of the red planet.
Space missions have provided valuable pressure,
wind and temperature data allowing the Martian
turbulence to be studied (e.g., [2-4]). Here we use a
spectral approach to analyse data from the InSight
and Perseverance meteorological sensors [5-6], and
the SuperCam microphone [7-8]. This method allows us to investigate how the pressure and wind
fluctuations, and thus PBL processes, vary as a
function of frequency, or spectral range.
High frequency atmospheric measurements: The
InSight pressure sensor [5] is capable of acquiring
data up to 20 Hz and operated continuously for long
periods of time in order to support the interpretation
of the seismological data. The InSight pressure were
at a higher frequency than any previous measurements and have shown unexpected behaviour in the
pressure fluctuations. For example, the spectral
slope seems to contradict the theoretical predictions
(Kolmogorov theory) for the cascade of the inertial
range [9].
The SuperCam Microphone onboard the Mars 2020
Perseverance rover is located at a height of 2.1 m
above the ground on the front of the SuperCam
instrument (Fig 2; [7-8]). With its high sampling
frequency (up to 100 kHz), the SuperCam
microphone can be used to probe the Martian
atmosphere at even higher frequencies than the

InSight pressure sensor. The SuperCam microphone
can, therefore, complement the lower frequency
wind and pressure measurements and provide a
window into previously unexplored regimes of
Martian atmospheric science.

Figure 1: The Insight lander. Credits: NASA/JPLCaltech.
Figure 2: The
SuperCam instrument, including the microphone, on the
surface of Mars.
Credits:
NASA/JPLCaltech.

Interpreting the kinetic energy spectrum:
Turbulent kinetic energy can be generated by
buoyancy driven convection and by wind shear
[11]. Once generated, the eddies experience nonlinear interactions as they cascade into smaller and
smaller eddies by an inertial mechanism.
Eventually, at the very small scale, viscous forces

Figure 3. Power spectral densities (PSDs) of the pressure fluctuations on InSight sol 550 in the periods 10 - 11
Local True Solar Time (left), and 23 - 24 Local True Solar Time (right).
become important and the eddies are dissipated
[12]. The PBL kinetic energy spectrum can be
viewed, therefore, as a superposition of several
components that exhibit different spectral slopes.
The different components will become dominant at
different length scales, at different local times and
at different heights above the surface.
Results: Here we first analyse the spectral characteristics of the pressure as measured by InSight, as a
function of both local time (Fig. 3) and season. In
doing so we attempt to isolate the different turbulent regimes, in addition to explaining why the
spectral slopes of the pressure data appear to contradict the theoretical predictions [9]. These results
allow us to probe the diurnal and seasonal trends of
the atmospheric dynamics at the InSight landing site
and how these trends are influenced, for example,
by wind jets [4,12], dust storms [10], or variations
in near-surface wind belts due to changes in Hadley
circulation with dust forcing [13-14].
Next we turn to the even smaller scales. We will
present the first observations of the Martian
dissipative regime thanks to the SuperCam
microphone. The length scale and timescale at
which the viscous dissipation should become
significant on Mars are theoretically estimated to be
0.02 m and ~0. 45 seconds, respectively [1,15]. The
dissipation regime of the Martian atmosphere
should, therefore, be observable at frequencies
above 2 Hz. There are some indications of a possible regime change at this frequency range in the
InSight pressure data (Fig. 3 and [9]), however, this
is at the very limits of the instrument capabilities
and should be interpreted with care [9]. We demonstrate that this theoretical prediction of a regime
transition close to 2 Hz is confirmed by the
SuperCam acoustic data ([16]; Fig 4).

Conclusions and Discussion: Using a spectral
approach we investigate the turbulent behaviour of
the Martian atmospheric. The InSight data, particularly the pressure sensor, are used to study diurnal
and seasonal atmospheric dynamics. In addition,
using the SuperCam microphone we can now study
Martian turbulence on new, previously inaccessible,
scales. Investigations into how the high frequency
spectral slope and regime transitionsvary with wind
speed, wind direction, local time and season are ongoing as we collect more data.

Shear
dominated
regime

Dissipation
regime

Figure 4. The PSD calculated for Perseverance’s
sensors; the SuperCam microphone (in Pa2/Hz over
167 s), MEDA pressure (in Pa2/Hz) and MEDA
wind data (in (m/s)2/Hz). Modified from [16].
As we go forward, in addition to studying the diurnal and seasonal effects, comparing the Mars 2020
and InSight data sets can provide information about
the effects of topographical forcing [12,17] in the
two different landing sites, where regional circulation is expected to be quite different [18-19]. Fur-

thermore, differences in aerodynamical roughness
length change the wind gradient and can create additional shear production of turbulence, and thermal
inertia differences will also affect the turbulence
kinetic energy level; a lower thermal inertia will
result in stronger temporal gradients of surface temperature and thus an enhanced turbulent mixing.
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[3] Larsen et al., BLM, 2002
[4] Chatain et al., GRL, 2021
[5] Banfield et al., SSR, 2018
[6] Rodriguez-Manfredi et al., SSR, 2021
[7] Maurice et al., SSR, 2021
[8] Mimoun et al., SSR, Submitted
[9] Banfield, Spiga et al., Nature Geo., 2020
[10] Temel et al., JGR-Planets, submitted
[11] Stull, 1988
[12] Savijärvi & Siili, J. Atmos. Sci., 1993
[13]Montabone et al., AdSpR, 2005
[14] Zhao et al., JGR-Planets, 2021
[15] Kolmogorov, 1941
[16] Maurice et al., Nature, 2022
[17] Spiga et al., Icarus 2011
[18] Spiga et al., SSR, 2018
[19] Newman et al., SSR, 2021