MARS 2020 MEDA MEASUREMENTS OF NEAR SURFACE
ATMOSPHERIC TEMPERATURES AT JEZERO
A. Munguira1 (asier.munguira@ehu.eus), R. Hueso1, A. Sánchez-Lavega1, M. de la Torre-Juarez2, G. Martinez3,
C. Newman4, J. Pla-García5, D. Banfield6, A. Vicente-Retortillo5, A. Lepinette5, J. A. Rodríguez-Manfredi5, B.
Chide7, T. Bertrand8, M. Lemmon9, E. Sebastian5, S. Navarro5, J. Gómez-Elvira10, J. Torres5, J. Martín-Soler5, J.
Romeral5, R. Lorenz11
1. Universidad del País Vasco UPV/EHU, Escuela de Ingeniería de Bilbao, Física Aplicada, Bilbao, Spain. 2. Jet
Propulsion Laboratory/California Institute of Technology, Pasadena, CA, USA. 3. Lunar and Planetary Institute,
Houston, TX, USA. 4. Aeolis Research, Chandler, AZ, USA. 5. Centro de Astrobiología (INTA-CSIC), Madrid,
Spain. 6. Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, NY, USA. 7. Los
Alamos National Laboratory, Los Alamos, NM, USA. 8. LESIA, Observatoire de Paris, Meudon, France. 9.
Space Science Institute, College Station, TX, USA. 10. Instituto Nacional de Técnica Aeroespacial (INTA),
Madrid, Spain. 11. Johns Hopkins Applied Physics Laboratory, Laurel, MD, USA.
1. Introduction: MEDA
Since February 18, 2021, Perseverance has been
exploring Jezero Crater (18ºN, 77ºE). The
meteorology of this location is being investigated
with the Mars Environmental Dynamics Analyzer
(MEDA) [1], which among many other sensors has 5
Air Temperature Sensors (ATS) to measure near
surface temperatures. These sensors are located at
two altitudes: two are at 0.85 m, in the front of the
rover, and three are at 1.45 m around the Remote
Sensing Mast (RSM), distributed azimuthally so that
at least one sensor is located upwind. Local air
temperatures are measured with a frequency that can
be as high as 2 Hz. In addition, the temperature of
the surface and at an approximate altitude of about
40 m are measured with the Thermal Infrared Sensor
(TIRS), which operates with a sampling frequency of
1 Hz. MEDA records atmospheric variables typically
over 50% of a full sol and its data allow to study
temporal scales ranging from micro-turbulence to
seasonal effects. Here we show data from the first
400 sols of the mission covering the period from
northern Spring (Ls=5º) to early Autumn (beyond
Ls=180º).
2. Methodology
Analysis of the ATS data requires understanding
the effects of the rover and its Radioisotope
Thermoelectric Generator (RTG) on the local air
temperatures being measured. Since the rover is
embedded in the rover’s thermal boundary layer,
different effects are observed along the sols due to
varying winds and rover orientations. The two
sensors at 0.85m are partially sheltered from
environment winds in the front of the rover and are
fully shielded from RTG effects. At nighttime, when
winds are weaker, residual contributions from the
rover may appear in the temperature data.
Measurements obtained by the combination of ATS
in the RSM at 1.45m are less affected by these
problems, since their azimuthal orientation
guarantees that at least one sensor is located upwind.

A comparison of ATS data and winds measured
by MEDA concludes that, in most cases, the
minimum temperature of the three ATS at the RSM
is obtained by the sensor that is located upwind, and
can be considered a good measurement of the
environment temperature. Similarly, at 0.85m the
sensor that is less exposed to environmental wind
generally records a warmer temperature than the
other.
We use an algorithm that analyzes the signals
from the 5 ATS and produces temperatures at
z=0.85m and z=1.45m preserving the thermal
fluctuations of the ATS that has lower temperatures.
This is done using a sliding time window of 1
minute. A comparison with simultaneous wind data
validates the selection done by the algorithm.
Temperature measurements with the TIRS
instrument are not subject to these complications,
and the only relevant effect that needs to be taken
into account is the time when direct solar light enters
the Field of View of the upward looking IR channel
that measures air temperatures. These measurements
correspond to a range of altitudes with a weighting
contribution function that peaks at z~40m. TIRS
measurements of surface temperatures rely on the
thermal infrared emission from a patch of terrain that
is significantly smaller than the one used in the Mars
Science Laboratory (MSL). Thus, surface
temperatures measured by MEDA/TIRS in Jezero
are more dependent on the specific location than
those measured by MSL in Gale crater.
3. Results
3.1. Diurnal Cycle
Figure 1 shows combined results of several sols
of air temperatures at z=1.45m (colors) and z=0.85m
(gray). The amplitude of the diurnal thermal cycle
driven by solar insolation is about 60 K. Daytime
hours show temperatures with an unstable vertical
thermal gradient that leads to strong convection
accompanied by thermal fluctuations of +/-6 K. As
the sun goes down in the sky, the afternoon hours

transits towards a null thermal gradient and null
thermal fluctuations when the Planetary Boundary
Layer collapses. In the evening and early night,
stable conditions are found. As the night advances, a
weak thermal inversion is broken, resulting in
apparently unstable thermal conditions. The weak
night-time winds, partially causing some residual
effects on the ATS at z=0.85m, complicate the
interpretation of the night-time thermal gradient. A
comparison with simultaneous TIRS temperatures
will be shown to unveil the complex nature of
nighttime thermal gradients at Jezero.

Fig. 1: ATS retrieved air temperatures between sols 34 and
40. Temperatures at z = 0.85m are shown in gray. A fit to
these data is shown with a black line. Colored data show
ATS measurements at z = 1.45m. Each color corresponds
to data from a different sol. The red line is a fit to those
data.

We will also show a characterization of the thermal
oscillations at different levels and a comparison with
the vertical thermal gradient.
3.2. Seasonal evolution
We find a progressive increase of temperatures
as the summer advances that is well matched at
z=1.45m by what the Mars Climate Database (MCD)
[2] predicts at Jezero for the standard dust
climatology. A Fourier analysis of ATS data allows
to study the contributions of different thermal tides
to the daily cycle of temperatures. These thermal
tides show a nearly constant behavior from Ls=6 to
Ls=135 with thermal amplitudes that smoothly
increase afterwards in a period of time where regular
clouds started to be observable in MEDA data from
other sensors. Figure 2 shows the coverage of the
data acquired and some of these effects.
3.3. Thermal oscillations and turbulence
The fast cadence of MEDA data allows us to
study the thermal oscillations at elevations from the
surface of z=0.85m to z~40m. Different regimes of
oscillations and turbulence are observed at different
times of the sol. Clear differences between the fully
convective regime near noon and the evening and
nighttime will be shown and compared with previous
studies at other Martian locations [3-4].

Figure 2: ATS temperatures at z=1.45m showing MEDA
coverage. The full map at high-resolution, especially when
combined with equivalent data at other altitudes, shows the
effects of different influences on temperatures that will be
discussed.

4. Dust Storm
A regional dust storm crossed Jezero at Ls=315.
The effects of the storm were strong and clear in the
temperature data. We will show results concerning
the specific response of temperatures to the storm at
different altitudes from the surface to z=40m, the
effects on thermal tides, the modification of the
vertical thermal gradient and the changes in the
amplitudes of thermal oscillations.
5. Discussion
A comparison of MEDA diurnal cycles of
temperature with model simulations obtained with
MRAMS, MarsWRF [5-6] (Figure 3) and seasonal
values from MCD [2] shows a general good
agreement between those models and MEDA
temperatures.

Figure 3: Simple example of comparison between
MarsWRF temperatures (black dots) and MEDA ATS
temperatures (colors) at Ls~60º.

A comparison of temperatures measured at
Jezero with other landing sites offers a new
opportunity to understand the different factors that
affect the Martian climate.
References:
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Mars Environmental Dynamics Analyzer, MEDA. A
suite of environmental sensors for the Mars 2020
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(E10), 24177–24194.
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temperature and related data from the Phoenix MET
station and their use in estimating turbulent heat
fluxes. Journal of Geophysical Research: Planets,
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[5] Newman et al. (2020). Multi-model
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[6] Pla-García et al., (2020). Meteorological
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