CHARACTERISTICS OF DUST DEVILS IN TWO PRE-SELECTED
LANDING REGIONS OF THE TIANWEN-1 MISSION – COMPARING
OBSERVATIONS AND PREDICTIONS BY NUMERICAL MODEL
Yemeng Wang , State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and
Technology, Macau, PR China (1909853ese30003@student.must.edu.mo), Kim-Chiu Chow, State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau, PR China, Jing
Xiao, State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology,
Macau, PR China
of maximum solar radiation in their local time. This
suggests that the temporal variation of solar radiation
due to the revolution of Mars is primarily responsible for the two-peak pattern of temporal distribution.
The spatial distributions of DDs both in ZA and
ZB are mainly related to the distribution of sensible
heat flux and surface-to-air temperature difference.
In ZA, solar radiation at surface dominates the spatial distribution of sensible heat flux, thus causing
the particular spatial distribution of DLIF. In ZB, our
results suggest that the spatial distribution of surfaceto-air temperature difference and sensible heat flux
are mainly determined by the albedo, and so the resulting DLIF is concentrated in the northwest. The
surrounding topography has little effect on the distribution of the predicted DDs. In the southeast corner
of ZB, the surface-to-air temperature difference is
relatively small which is not favorable for the occurrence of DDs.
ZA

ZA

ZB

ZB

Figure 1. (Top) Topography (contour) and spatial
distribution of DDs (white dots) from observations in
Zone A and zone B (Red boxes). (Bottom) Dust lifted by dust devils (shading) from MarsWRF.
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ADDs

Abstract:
The spatial and temporal distribution of dust devils (DDs) in two pre-selected landing regions (ZA
and ZB, Figure 1) of the Tianwen-1 mission in
southern Utopia Planitia have been investigated by
using images from the Context Camera (CTX) of the
Mars Reconnaissance Orbiter (MRO). From the images of the regions in 8 Martian years, no DD was
found in ZA while 77 DDs were found in ZB. The
observed DDs are mainly distributed in the northeastern part of ZB. The temporal variation of the
observed DDs shows a prominent two-peak pattern
in their local early spring and late summer (Figure 2).
The size and height of the observed DDs have also
been evaluated from the images, and they show a
similar temporal variation as the occurrence.
These patterns are also supported by the results
of the numerical simulations with the Mars climate
model MarsWRF model. Some questions have been
put forward based on the observational results. For
instance, why DDs are more in ZB compared with
ZA? Why there are two peaks for the occurrence of
DDs in the temporal distribution? What are the possible factors which determine the spatial distribution
of DDs in ZA and ZB (e.g., DDs are mainly in the
northeastern part of ZB)? To investigate the possible
conditions pertinent to these observed patterns of DD
distribution, some analysis based on the thermodynamic theory of heat engine was performed using the
output of MarsWRF.
DDs are mainly concentrated in the first half of
the year and there are more DDs in ZB than that in
ZA (Figure 2). The analysis for simulated results
suggests that the difference in dust lifting by DDs
(DLIF) between ZA and ZB is mainly dominated by
the difference in sensible heat flux, which is mainly
caused by the surface-to-air temperature difference.
Thermal efficiency plays a relatively minor role.
Furthermore, ZB has a stronger net short wave radiative flux at the surface due to the lower albedo (~
0.205) at the surface than ZA (~ 0.229). Overall, the
results of the analysis suggest that more DDs in ZB
are mainly caused by the lower albedo in ZB.
Both the observed and predicted DDs have a
two-peak feature in their local early spring and late
summer, and are generally coincident with the time

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120 150 180 210 240 270 300 330 360

solar longitude (degree)

Figure 2. Time series of the number of DDs from
CTX images in the study area (left), and total daily
dust lifting by dust devils (DLIF) averaged in ZA
(blue dots) and ZB (red dots)(right).