Nocturnal turbulence at Jezero driven by the onset of a low-level jet
as determined from MRAMS modeling and MEDA measurements
J. Pla-García1, A. Munguira2, S. Rafkin3, R. Hueso2, A. Sánchez-Lavega2, M. de la Torre4, D. Viúdez-Moreiras1, C. Newman5, T. Bertrand6, Teresa del Río2, N. Murdoch7, G. Martínez8, H. Savijarvi9, B. Chide7, M. Richardson5, J.A. RodríguezManfredi1
1

Centro de Astrobiología (CSIC- INTA), Madrid, Spain (jpla@cab.inta-csic.es),
Universidad del País Vasco (UPV/EHU), Bilbao, Spain,
3
Southwest Research Institute, Boulder, CO, USA,
4
Jet Propulsion Laboratory/California Institute of Technology, Pasadena, CA, USA.
5
Aeolis Research, Chandler, AZ, USA,
6
Paris Observatory, France
7
ISAE-SUPAERO, Université de Toulouse, 31055 Toulouse, France
8
Lunar and Planetary Institute, Houston, TX, USA
9
Finnish Meteorological Institute, Helsinki, Finland
2

Abstract:
The aim of this investigation is to carry out a study of
the variability of nocturnal atmospheric turbulence at
Jezero crater supported by modeling effort and monitored
by MEDA. Although nighttime conditions in Mars' PBL
are highly stable and turbulence is usually not expected,
because of strong radiative cooling efficiently inhibiting
convection, both observations and modeling shows the
development of nighttime local turbulence. The rapid
turbulent kinetic energy (hereafter TKE), wind and pressure fluctuations observed during nighttime both with
MRAMS mesoscale modeling and MEDA is a clear indicative of nocturnal turbulence. The origin of this nocturnal
turbulence is explored with MRAMS and, as opposed to
Gale crater, low evidence of significant gravity waves
activity during the whole period studied was found. On the
contrary, the nighttime turbulence at Jezero crater could be
shear driven and may be explained due to an enhanced
mechanical turbulence produced by increasingly strong
shear (onset of a strong low-level jet) at the nocturnal
inversion interface. As the nocturnal inversion develops,
the winds above become decoupled from the surface and
the decrease in friction produces a net acceleration. Once
the critical Richardson Number is reached (Ri ∼< 0.25),
shear instabilities can mix warmer air aloft down to the
surface. A dustier atmosphere contributes to nighttime
turbulence strengthening the nighttime low-level jet and
weakening the near-surface atmospheric stability.

1. Introduction
The Mars 2020 Perseverance rover landed in Mars in
February 2021 at 18.44N 77.45E within and near the
northwest rim of Jezero crater. The MEDA sensor suite
aboard Perseverance rover [1] includes a dust and optical
radiation sensor (RDS) with a dedicated camera
(SkyCam), a pressure sensor (PS), a relative humidity
sensor (HS), a wind sensor (WS), five air temperature
sensors (ATS), and a thermal infrared sensor for upwelling
infrared flux and ground temperature determination
(TIRS). MEDA acquires data typically over 50% of a full
sol. After more than 380 sols in Mars, the data allows to
explore the changing dynamics of the Martian atmosphere
from northern Spring (Ls=5º, sol 1) to northern Autumn
Equinox (Ls=180º, sol 361) and beyond.

2. MRAMS mesoscale simulations design
In an effort to better understand the different me-

teorological environments inside Jezero crater,
MRAMS was applied to Mars 2020 landing site
region using nested grids with a spacing of 330 meters on the innermost grid that is centered over the
landing site [2]. MRAMS is ideally suited for this
investigation; the model is explicitly designed to
simulate Mars’ atmospheric circulations at the
mesoscale and smaller with realistic, high-resolution
surface properties. The model is run for 4 sols with 4
grids and then the 3 additional grids are added and
run for at least 3 more sols. Initialization and boundary condition data are taken from a NASA Ames
GCM simulation with column dust opacity driven by
zonally-averaged TES retrievals. Vertical dust distribution is given by a Conrath-v parameterization that
varies with season and latitude. The lowest thermodynamic level (where temperature and pressure are
prognosed) is ∼14m above the ground. Ideally, the
first vertical level would be located at the height of
the MEDA sensors, but this is not computationally
practical.
3. Nighttime turbulence modeled with
MRAMS
The effect of subgrid-scale eddies is captured
within MRAMS via a prognostic TKE (Figure 1)
equation [3]. MRAMS shows a peak in TKE during
the afternoon, which is consistent with the modeled
high-frequency variations in air temperatures [2,
Figure 4]. The sudden increase in air temperature
during the evenings [2, Figure 4] at the onset of
radiative cooling is produced by mechanically driven
turbulence since the atmosphere is stable and nonconvective in the evening (Figure 2).
The model does often show small increases of
TKE during the night (Figure 1), especially during
Ls=180º (corresponding to Mars 2020 sol 362) and
some during Ls 105 and Ls 160 (corresponding to
Mars 2020 sols 216 and 326), that could be associated with the turbulent aspects of the nighttime dynamical flows when compared with nearby locations
with more flat topography. During the late evening
and night, MRAMS is resolving thermal variations

[2, Figure 4] and does often show small increases of
TKE at that time (Figure 1). The rapid air temperature fluctuations modeled at night in all seasons is
indicative of nocturnal turbulence.
There is low evidence of significant wave activity during the whole period studied and only some
gravity waves were found. The nighttime turbulence
could be attributed to shear driven turbulence and
may be explained due to an enhanced mechanical
turbulence driven by increasingly strong shear, with
the onset of the nocturnal low-level jet, at the nocturnal inversion interface (an example on Figure 3).
As the nocturnal inversion develops, the winds
above become decoupled from the surface and the
decrease in friction produces a net acceleration [4, 5,
6, 7]. Once the critical Richardson Number is
reached (Ri ∼< 0.25, Figure 4), shear instabilities
can mix warmer air aloft down to the surface [8, 9,
10].
The dustier atmosphere, when arrival of northern
autumn equinox, also contributes to decrease the
nighttime Richardson number by two means:
strengthening of the nighttime low-level jet deeping
the near-surface wind shear and weakening nearsurface atmospheric stability by increasing the
nighttime surface temperature and decreasing of
atmospheric temperature.
A third possible strengthening of the nighttime
turbulence at Jezero could be the convergence, after
01:00 LSTS, of downslope winds blowing from NW
rim fighting against SE winds blowing both from
east crater rims and from Jezero mons (located SE
outside the crater), producing a big whirlpool inside
the crater (Figure 5) that could be the responsible of
the high variability of wind directions observed by
MEDA.
3. Nighttime turbulence observed with MEDA
The rapid fluctuations of pressure (moreover during
high dust periods), TKE (derived only with horizontal wind speeds, that will be updated with vertical
winds in the future) and wind speeds observed during nighttime with MEDA (Figures 6, 7 and 8) is a
clear indicative of nocturnal turbulence. There are
two higher turbulence periods around sol #78
(~Ls=42º) and around sol #290 (~Ls=141º), and a
lower turbulence period around sol #200 (~Ls=97º,
Figure 6 left) for the 20:00 to 00:00 period. After
01:00, the winds are very weak and all the correlations and mixings tend to be more diluted (Figure 6
right).

Ls0
Ls60 (~sol 117)
Ls90 (~sol 183)
Ls105 (~sol 216)
Ls160 (~sol 326)
Ls180 (~sol 362)
Ls270

Figure 1: TKE diurnal cycle predicted with
MRAMS for Jezero crater at Ls0, 60, 90, 105, 160,
180 and 270.
Air temperature vertical profiles at Jezero

Figure 2: MRAMS vertical profiles of air temperature for Ls180 at Mars 2020 location corresponding
to sol #362.

LOW LEVEL JET
White arrows:
Zonal + vertical wind
(exaggerated x5)
LOW LEVEL JET

Black contours:
Turbulence (TKE)

East rim

West rim

Colored shadowed = Total horizontal wind (N-S meridional + E-W zonal)

Figure 3: MRAMS vertical cross-section (Jezero’s
west rim to east rim) at 21:35 LTST of Ls=180º corresponding to Mars 2020 sol #362- of total wind
(zonal + meridional) in colored shadowed, zonal +
vertical (exaggerated x5) wind in white arrows and
TKE in black contours. The west crater rim is the hill
on the left. Perseverance rover is located at x ≈ 17
km. Shear instabilities mix warmer air aloft down to
the surface.
Wind magnitude

20:00 LTST

4. Figures
00:00 LTST

04:00 LTST

Wind shear

Richardson number

TKE

Figure 4: MRAMS vertical profiles of wind magnitude, wind shear, Richardson number (Ri) and TKE
for Ls180 at Mars 2020 location corresponding to
Mars 2020 sol #362 (Ls=180º). Once the critical
Richardson Number is reached (Ri ∼< 0.25, red
line), shear instabilities can mix warmer air aloft
down to the surface.

LTST (left) and 01:00 to 04:00 LTST (right). After
01:00, the winds are very weak and all the correlations and mixings tend to be more diluted.

Figure 7: MEDA TKE (derived only with horizontal
wind speeds, that will be updated with vertical winds
in the future), wind direction and horizontal wind
speed instantaneous (with a cadence of 1 Hz) measurements for the period 00:14 to 00:23 LTST at sol
#73.

Figure 5: Near-surface winds (vectors) and potential
temperature (shaded) as predicted on numerical grid
5. Vectors are plotted at every other grid point. Topography contours are shown in black. Wind vector
scale is shown in the bottom right area of the panels.
hh:mm LTST on the top right. A big whirlpool inside the crater could be the responsible of the high
variability of wind directions observed by MEDA
after 01:00 LTST.
20:00 to 23:00 LMST. MEDA fluctuations

01:00 to 04:00 LMST. MEDA fluctuations

Figure 8: Diurnal cycle of MEDA TKE (derived
only with horizontal wind speeds, that will be updated with vertical winds in the future) averaged over 5
min for sols #73-87.
5. References
[1] Rodriguez-Manfredi et al. 2020; [2] Pla-Garcia et
al. 2021; [3] Mellor and Yamada 1974; [4] Davis
2000; [5] Blackadar 1957; [6] Thorpe and Guymer
1977; [7] Mahrt 1981; [8] Miles 1961; [9] Banfield
et al. 2020; [10] Chatain et al. 2021

Figure 6: MEDA TKE (derived only with horizontal
wind speeds, that will be updated with vertical winds
in the future), wind speeds and pressure fluctuations
averaged over 5 min for the periods 20:00 to 00:00