NASA's Mars Science Laboratory rover Curiosity (MSL) has measured simultaneous fluctuations in wind and atmospheric pressure caused by passing convective vortices, i.e. dustless dust devils. We study ...the dynamics of these vortices by fitting a mathematical vortex model to the wind and pressure measurements of MSL. The model matches the data adequately well in 29 out of the 33 studied vortex pass events having sufficient data quality. Clockwise and counterclockwise rotating directions are equally common among the studied convective vortices. The vortices seem to prefer certain trajectories, e.g. avoiding steep slopes. However, our results show that due to sensitivity constraints of the method, central pressure drops of Martian dust devils can usually not be accurately determined by fitting a theoretical vortex model to simultaneous pressure and wind measurements of a single station. We also present a methodology extension for further constraining the trajectories and the strengths of dust laden vortices (i.e. dust devils), based on concurrent in-situ solar irradiance measurements. We apply this methodology to the only evidently dust laden vortex in our data set and show that its dust lifting capacity is probably based not only on wind stress lifting.
•Martian dust devils are studied by in-situ wind, pressure, and UV data.•A methodology for fitting a mathematical vortex model to the data is presented.•Clockwise and counterclockwise rotating vortices are equally common.•The dust devils prefer relatively flat terrain.•Martian dust devils appear to lift dust not only by wind stress.
The Phoenix lander operated on the surface of Mars for circa 5 months in 2008. One of its scientific instruments is an atmospheric pressure sensor called MET-P. We perform a comprehensive study to ...identify all error sources affecting the data measured by MET-P and to generate methods for compensating these errors. Our results show that MET-P performed much better than was reported immediately after the mission (Taylor et al., 2010). The error limits of the original calibrated Phoenix pressure data currently available in NASA’s Planetary Data System (Dickinson, 2008) are from −5.3 Pa to +3.5 Pa. Further, almost no temperature-dependent error exists in the original calibrated MET-P data. However, we identify a previously unknown error source, temperature hysteresis, which causes minor peaks in the measured pressure curve (<0.4 Pa). A version of the Phoenix pressure data generated by applying all the error compensations developed in this study is available on Mendeley Data (Kahanpää et al., 2019). The study is based on the re-analysis of the original test data of MET-P, the analysis of the engineering data measured during the mission on Mars and during the interplanetary cruise, and laboratory tests with the Reference Model of the MET-P sensor. Temperature dependent errors are evaluated by comparing the readings of two sensor heads with different sensitivities, measuring the same quantity. The principle of this method is applicable also for other types of instruments.
•The quality of the atmospheric pressure data of the Mars Phoenix lander is studied.•The data are more accurate than reported before.•A corrected version of the data is available on Mendeley Data.•There are almost no temperature-dependent errors.•Temperature hysteresis causes small deviations.
Surface-based measurements of terrestrial and martian dust devils/convective vortices provided from mobile and stationary platforms are discussed. Imaging of terrestrial dust devils has quantified ...their rotational and vertical wind speeds, translation speeds, dimensions, dust load, and frequency of occurrence. Imaging of martian dust devils has provided translation speeds and constraints on dimensions, but only limited constraints on vertical motion within a vortex. The longer mission durations on Mars afforded by long operating robotic landers and rovers have provided statistical quantification of vortex occurrence (time-of-sol, and recently seasonal) that has until recently not been a primary outcome of more temporally limited terrestrial dust devil measurement campaigns. Terrestrial measurement campaigns have included a more extensive range of measured vortex parameters (pressure, wind, morphology, etc.) than have martian opportunities, with electric field and direct measure of dust abundance not yet obtained on Mars. No martian robotic mission has yet provided contemporaneous high frequency wind and pressure measurements. Comparison of measured terrestrial and martian dust devil characteristics suggests that martian dust devils are larger and possess faster maximum rotational wind speeds, that the absolute magnitude of the pressure deficit within a terrestrial dust devil is an order of magnitude greater than a martian dust devil, and that the time-of-day variation in vortex frequency is similar. Recent terrestrial investigations have demonstrated the presence of diagnostic dust devil signals within seismic and infrasound measurements; an upcoming Mars robotic mission will obtain similar measurement types.
History and Applications of Dust Devil Studies Lorenz, Ralph D.; Balme, Matthew R.; Gu, Zhaolin ...
Space Science Reviews,
11/2016, Volume:
203, Issue:
1-4
Journal Article, Book Review
Peer reviewed
Open access
Studies of dust devils, and their impact on society, are reviewed. Dust devils have been noted since antiquity, and have been documented in many countries, as well as on the planet Mars. As ...time-variable vortex entities, they have become a cultural motif. Three major stimuli of dust devil research are identified, nuclear testing, terrestrial climate studies, and perhaps most significantly, Mars research. Dust devils present an occasional safety hazard to light structures and have caused several deaths.
•The signature of equator crossing frontal systems on Mars has been detected by the Curiosity Rover's pressure sensor.•These systems occasionally trigger regional dust storms in the Southern ...Hemisphere and are thus important the planet's dust cycle.•The periods and seasonal variations of these equator crossing eddies suggest a complex dynamical response to seasonal changes and dust storms.•This work opens up a new line of research for Mars atmospheric dynamics.
The Rover Environmental Monitoring Station (REMS) on the Curiosity Rover is operating in the Southern Hemisphere of Mars and is detecting synoptic period oscillations in the pressure data that we attribute to Northern Hemisphere transient eddies. We base this interpretation on the similarity in the periods of the eddies and their seasonal variations with those observed in northern midlatitudes by Viking Lander 2 (VL-2) 18 Mars years earlier. Further support for this interpretation comes from global circulation modeling which shows similar behavior in the transient eddies at the grid points closest to Curiosity and VL-2. These observations provide the first in situ evidence that the frontal systems often associated with “Flushing Dust Storms” do cross the equator and extend into the Southern Hemisphere.
In situ surface pressures measured at 2 s intervals during the 150 sol Phoenix mission are presented and seasonal variations discussed. The lightweight Barocap®/Thermocap® pressure sensor system ...performed moderately well. However, the original data processing routine had problems because the thermal environment of the sensor was subject to more rapid variations than had been expected. Hence, the data processing routine was updated after Phoenix landed. Further evaluation and the development of a correction are needed since the temperature dependences of the Barocap sensor heads have drifted after the calibration of the sensor. The inaccuracy caused by this appears when the temperature of the unit rises above 0°C. This frequently affects data in the afternoons and precludes a full study of diurnal pressure variations at this time. Short‐term fluctuations, on time scales of order 20 s are unaffected and are reported in a separate paper in this issue. Seasonal variations are not significantly affected by this problem and show general agreement with previous measurements from Mars. During the 151 sol mission the surface pressure dropped from around 860 Pa to a minimum (daily average) of 724 Pa on sol 140 (Ls 143). This local minimum occurred several sols earlier than expected based on GCM studies and Viking data. Since battery power was lost on sol 151 we are not sure if the timing of the minimum that we saw could have been advanced by a low‐pressure meteorological event. On sol 95 (Ls 122), we also saw a relatively low‐pressure feature. This was accompanied by a large number of vertical vortex events, characterized by short, localized (in time), low‐pressure perturbations.
The impact of dust aerosols on the climate and environment of Earth and Mars is complex and forms a major area of research. A difficulty arises in estimating the contribution of small-scale dust ...devils to the total dust aerosol. This difficulty is due to uncertainties in the amount of dust lifted by individual dust devils, the frequency of dust devil occurrence, and the lack of statistical generality of individual experiments and observations. In this paper, we review results of observational, laboratory, and modeling studies and provide an overview of dust devil dust transport on various spatio-temporal scales as obtained with the different research approaches. Methods used for the investigation of dust devils on Earth and Mars vary. For example, while the use of imagery for the investigation of dust devil occurrence frequency is common practice for Mars, this is less so the case for Earth. Modeling approaches for Earth and Mars are similar in that they are based on the same underlying theory, but they are applied in different ways. Insights into the benefits and limitations of each approach suggest potential future research focuses, which can further reduce the uncertainty associated with dust devil dust entrainment. The potential impacts of dust devils on the climates of Earth and Mars are discussed on the basis of the presented research results.
•Detection of synchronous modulations of pressure and air and ground surface temperatures.•Diurnal and seasonal variation of dynamic pressure fluctuations.•Novel method to estimate winds at Gale ...Crater.•Year-to-year repeatability of these environmental phenomena.
The Rover Environmental Monitoring Station (REMS) instrument on-board the Mars Science Laboratory (MSL) has acquired unprecedented measurements of key environmental variables at the base of Gale Crater. The pressure measured by REMS shows modulations with a very structured pattern of short-time scale (of the order of seconds to several minutes) mild fluctuations (typically up to 0.2 Pa at daytime and 1 Pa at night-time). These dynamic pressure oscillations are consistent with wind, air and ground temperature modulations measured simultaneously by REMS. We detect the signals of a repetitive pattern of upslope/downslope winds, with maximal speeds of about 21 m/s, associated with thermal changes in the air and surface temperatures, that are initiated after sunset and finish with sunrise proving that Gale, a 4.5 km deep impact crater, is an active Aeolian environment. At nighttime topographic slope winds are intense with maximal activity from 17:00 through 23:00 Local Mean Solar Time, and simultaneous changes of surface temperature are detected. During the day, the wind modulations are related to convection of the planetary boundary layer, winds are softer with maximum wind speed of about 14 m/s. The ground temperature is modulated by the forced convection of winds, with amplitudes between 0.2 K and 0.5 K, and the air temperatures fluctuate with amplitudes of about 2 K. The analysis of more than one and a half Martian years indicates the year-to-year repeatability of these environmental phenomena. The wind pattern minimizes at the beginning of the south hemisphere winter (Ls 90) season and maximizes during late spring and early summer (Ls 270). The procedure that we present here is a useful tool to investigate in a semi-quantitative way the winds by: i) filling both seasonal and diurnal gaps where wind measurements do not exist, ii) providing an alternative way for comparisons through different measuring principia and, iii) filling the gap of observation of short-time wind variability, where the REMS wind sensor is blind.
Two hundred fifty‐two transient drops in atmospheric pressure, likely caused by passing convective vortices, were detected by the Rover Environmental Monitoring Station instrument during the first ...Martian year of the Mars Science Laboratory (MSL) landed mission. These events resembled the vortex signatures detected by the previous Mars landers Pathfinder and Phoenix; however, the MSL observations contained fewer pressure drops greater than 1.5 Pa and none greater than 3.0 Pa. Apparently, these vortices were generally not lifting dust as only one probable dust devil has been observed visually by MSL. The obvious explanation for this is the smaller number of strong vortices with large central pressure drops since according to Arvidson et al. ample dust seems to be present on the surface. The annual variation in the number of detected convective vortices followed approximately the variation in Dust Devil Activity (DDA) predicted by the MarsWRF numerical climate model. This result does not prove, however, that the amount of dust lifted by dust devils would depend linearly on DDA, as is assumed in several numerical models of the Martian atmosphere, since dust devils are only the most intense fraction of all convective vortices on Mars, and the amount of dust that can be lifted by a dust devil depends on its central pressure drop. Sol‐to‐sol variations in the number of vortices were usually small. However, on 1 Martian solar day a sudden increase in vortex activity, related to a dust storm front, was detected.
Key Points
Signs of 252 dustless convective vortices have been detected by Mars Science Laboratory
The annual variation in vortex occurrence rate followed approximately dust devil activity predicted by a numerical climate model
A transient increase in vortex activity related to a dust storm front was detected by meteorological measurements on Mars
Surface pressure measurements on Mars have revealed a wide variety of atmospheric phenomena. The Mars Science Laboratory Rover Environmental Monitoring Station pressure sensor dataset is now the ...longest duration record of surface pressure on Mars. We use the first 2580 martian sols, nearly 4 Mars years,of measurements to identify atmospheric pressure waves with periods of tens of minutes to hours using wavelet analysis on residual pressure after the tidal harmonics are removed. We find these waves have a clear diurnal cycle with strongest activity in the early morning and late evening and a seasonal cycle with the strongest waves in the second half of the martian year (Ls= 180-360°). The strongest such waves of the entire mission occurred during the Mars Year 34 global dust storm. Comparable atmospheric waves are identified using atmospheric modeling with the MarsWRF general circulation model in a “nested” high spatial resolution mode. With the support of the modeling, we find these waves best fit the expected properties of inertia-gravity waves with horizontal wavelengths of O(100s) of km.
PLAIN LANGUAGE SUMMARY
Measuring air pressure from the surface of Mars has revealed a wide variety of atmospheric phenomena. The Curiosity rover's record or surface air pressure is now the longest yet made on Mars.We use the first ~8 years of Curiosity's pressure observations to look for atmospheric waves with periods of tens of minutes to hours. We find these waves have a clear pattern in their daily behavior with the strongest activity in the early morning and late evening and a seasonal cycle with the strongest waves in the second half of the martian year (Northern hemisphere fall and winter). The strongest such waves occurred in 2018 during a global dust storm. We find comparable waves in atmospheric modeling. With the support of modeling, we find these waves best fit the expected properties of buoyancy waves forced by airflow over topography with horizontal wavelengths of 100-1000 km.
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