Simulations with the Max Planck Institute Martian general circulation model for Martian years 28 and 34 reveal details of the water "pump" mechanism and the role of gravity wave (GW) forcing. Water is advected to the upper atmosphere mainly by upward branches of the meridional circulation: in low latitudes during equinoxes and over the south pole during solstices. Molecular diffusion plays little role in water transport in the middle atmosphere and across the mesopause. GWs modulate the circulation and temperature during global dust storms, thus changing the timing and intensity of the transport. At equinoxes, they facilitate water accumulation in the polar warming regions in the middle atmosphere followed by stronger upwelling over the equator. As equinoctial storms decay, GWs tend to accelerate the reduction of water in the thermosphere. GWs delay the onset of the transport during solstitial storms and change the globally averaged amount of water in the upper atmosphere by 10-25%.
Production of runaway electron avalanches and gamma rays originating inside Martian dust storms are studied using Monte Carlo simulations. In the absence of in situ measurements, we use theoretical predictions of electric fields inside dust storms. Electrons are produced through the relativistic runaway electron avalanches process, and energetic photons are results of the bremsstrahlung scattering of the electrons with the air. Characteristic lengths of the runaway electron avalanche for different electric fields and the energy spectrum of electrons are derived and compared to their terrestria…
We analyze the onset and initial expansion of the 2018 Martian Global Dust Storm (GDS 2018) using ground-based images in the visual range. This is the first case of a confirmed GDS initiating in the Northern Hemisphere. A dusty area extending about 1.4x10e5 km^2 and centered at latitude +31.7° $\pm$ 1.8° and west longitude 18° $\pm$ 5°W in Acidalia Planitia was captured on 30 and 31 May 2018 (Ls = 184.9°). From 1 to 8 June, daily image series showed the storm expanding southwards along the Acidalia corridor with velocities of 5 m/s, and simultaneously progressing eastwards and westwards with h…
Lower atmospheric global dust storms affect the small- and large-scale weather and variability of the whole Martian atmosphere. Analysis of the CO$_2$ density data from the Neutral Gas and Ion Mass Spectrometer instrument (NGIMS) on board NASA's Mars Atmosphere Volatile EvolutioN (MAVEN) spacecraft show a remarkable increase of GW-induced density fluctuations in the thermosphere during the 2018 major dust storm with distinct latitude and local time variability. The mean thermospheric GW activity increases by a factor of two during the storm event. The magnitude of relative density perturbation…
Airborne dust is the main climatic agent in the Martian environment. Local dust storms play a key role in the dust cycle; yet their life cycle is poorly known. Here we use mesoscale modeling that includes the transport of radiatively active dust to predict the evolution of a local dust storm monitored by OMEGA on board Mars Express. We show that the evolution of this dust storm is governed by deep convective motions. The supply of convective energy is provided by the absorption of incoming sunlight by dust particles, rather than by latent heating as in moist convection on Earth. We propose to …
Martian planet-encircling dust storms or global dust storms (GDS), resulting from the combined influence of local and regional storms, are uncommon aperiodic phenomena: with an average frequency of approximately one every 3-4 MY, they produce a substantial rise in the atmospheric dust loading that lasts from weeks to months and have a significant impact on the atmospheric properties, energy budget, and global circulation. During the 2018/MY34 global dust storm, initiated at L_S = 185$^\circ$ (30-31 May 2018), an intensive atmospheric science campaign was carried out by the Mars Science Laborat…
We study the 2018 Martian Global DustStorm (GDS 2018) over the Southern Polar Region using images obtained by the Visual Monitoring Camera (VMC) on board Mars Express during June and July 2018. Dust penetrated into the polar cap region but never covered the cap completely, and its spatial distribution was nonhomogeneous and rapidly changing. However, we detected long but narrow aerosol curved arcs with a length of 2,000-3,000 km traversing part of the cap and crossing the terminator into the night side. Tracking discrete dust clouds allowed measurements of their motions that were towards the t…
In this study we present the analysis of the dust properties of a local storm imaged in the Atlantis Chaos region on Mars by the OMEGA imaging spectrometer on March 2nd 2005. We use the radiative transfer model MITRA to study the dust properties at solar wavelengths between 0.5 μm and 2.5 μm and infer the connection between the local storm dynamics and the topography. We retrieve maps of effective grain radius (reff), optical depth at 9.3 μm (τ9.3) and top altitude (ta) of the dust layer. Our results show that large particles (reff = 1.6 μm) are gathered in the centre of the storm (lat=33.5° S…
The Atmospheric Chemistry Suite (ACS) instrument onboard the ExoMars Trace Gas Orbiter (TGO) ESA-Roscosmos mission began science operations in March 2018. ACS Mid InfraRed (MIR) channel notably provides solar occultation observations of the martian atmosphere in the 2.3 - 4.2 $μ$m spectral range. Here we use these observations to characterize water ice clouds before and during the MY 34 Global Dust Storm (GDS). We developed a method to detect water ice clouds with mean particle size $\leq$ 2 $μ$m, and applied it to observations gathered between $L_s=165^\circ$ and $L_s=243^\circ$. We observe a…
Observations of water ice clouds and aerosols on Mars can provide important insights into the complexity of the water cycle. Recent observations have indicated an important link between dust activity and the water cycle, as intense dust activity can significantly raise the hygropause, and subsequently increase the escape of water after dissociation in the upper atmosphere. Here present observations from NOMAD/TGO that investigate the variation of water ice clouds in the perihelion season of Mars Year 34 (April 2018-19), their diurnal and seasonal behavior, and the vertical structure and microp…
A diagnosis of the Ar densities measured by the Neutral Gas and Ion Mass Spectrometer aboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) and the temperatures derived from these densities shows that solar activity, solar insolation, and the lower atmospheric dust are the dominant forcings of the Martian thermosphere. A methodology, based on multiple linear regression analysis, is developed to quantify the contributions of the dominant forcings to the densities and temperatures. The results of the present study show that a 100 sfu (solar flux units) change in the solar activity results in…
Impacting the dayside Martian ionosphere from above and below: Effects of the impact of CIRs and ICMEs close to aphelion (April 2021) and during dust storms (June-July 2022) seen with MAVEN ROSE
In this study, we extracted the amplitudes of the gravity waves (GWs)from the neutral densities measured in situ by the neutral gas and ion mass spectrometer aboard the Mars atmosphere and volatile evolution mission. The spatial and temporal variabilities of the GWs show that solar activity (the F10.7 cm solar flux corrected for a heliocentric distance of 1.66 AU), solar insolation, and the lower atmospheric dust are the dominant drivers of the GW variability in the thermosphere. We developed a methodology in which a linear regression analysis has been used to disentangle the complex variabili…
Numerous laboratory experiments, starting in the Viking Lander era, have reported that frictional interactions between Martian analog dust grains can catalyze electrostatic processes (i.e. triboelectrification). Such findings have been cited to suggest that Martian dust devils and dust storms may sustain lightning storms, glow discharges, and other complex electrostatic phenomena. However, in many cases (if not most), these experiments allowed Martian dust simulant grains to contact foreign surfaces (for instance, the wall of an environmental chamber or other chemically dissimilar particles). …
Coagulation of particles occurs when two particles collide and stick together. In the Martian atmosphere, dust coagulation would increase the effective particle size, as small particles accrete to larger particles. Murphy et al. (1990) showed that Brownian coagulation of dust in the Martian atmosphere was not significant, due to the low dust particle mixing ratios, while Montmessin et al. (2002) and Fedorova et al. (2014) showed that it mostly involves particle radii smaller than 0.1 um. However, the effects of coagulation have never been explored in 3D, during a global dust storm, i.e. in pre…
Much of the surface of Mars is covered by dunes, ripples, and other features formed by the blowing of sand by wind, known as saltation. In addition, saltation loads the atmosphere with dust aerosols, which dominate the Martian climate. We show here that saltation can be maintained on Mars by wind speeds an order of magnitude less than required to initiate it. We further show that the resulting hysteresis effect causes saltation to occur for much lower wind speeds than previously thought. These findings have important implications for the formation of dust storms, sand dunes, and ripples on Mar…
We report the ubiquitous occurrence of nighttime temperature inversions in the tropical martian atmosphere during the dusty season, as observed by the Mars Climate Sounder. The inversions are linked to the occurrence of large-scale regional dust storms, with their strengths largely correlated to the strengths of the dust storms. Inversions strengthen between 2 am and 4 am, with the bases of the inversions getting cooler, and the tops of the inversions getting warmer. The inversions are strongest around Tharsis and Terra Sabaea, which are higher-elevation regions, suggesting they are forming du…
Previous observations have shown that, during Martian dust storms, the peak of the ionosphere rises in altitude. Observational studies of this type, however, have been extremely limited. Using 13 years of ionospheric peak altitude data from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument on Mars Express, we study how the peak altitude responded to dust storms during six different Mars Years (MY). The peak altitude increased $\sim$10-15 km during all six events, which include a local dust storm (MY 33), three regional regional dust storms (MYs 27, 29, and 32),…
The pervasive Mars dust is continually transported between the surface and the atmosphere. When on the surface, dust increases the albedo of darker underlying rocks and regolith, which modifies climate energy balance and must be quantified. Remote observation of surface albedo absolute value and albedo change is however complicated by dust itself when lifted in the atmosphere. Here we present a method to calculate and map the bolometric solar hemispherical albedo of the Martian surface using the 2004 - 2010 OMEGA imaging spectrometer dataset. This method takes into account aerosols radiative t…
The winter polar vortices on Mars are annular in terms of their potential vorticity (PV) structure, a phenomenon identified in observations, reanalysis and some numerical simulations. Some recent modeling studies have proposed that condensation of atmospheric carbon dioxide at the winter pole is a contributing factor to maintaining the annulus through the release of latent heat. Dust and topographic forcing are also known to be causes of internal and interannual variability in the polar vortices. However, coupling between these factors remains uncertain, and previous studies of their impact on…
We analyze Mars Climate Sounder temperature and aerosol data in the tropics to study atmospheric tides and their relation to the dust and water ice distributions. Our results from data covering Mars years (MY) 29-35 reveal that MY29 has large amplitude non-migrating thermal tides during southern hemisphere spring equinox that are not observed at the same local time in any other year. It is the nighttime temperatures that are most perturbed compared to other years, with strong temperature inversions at 35-55 km altitude. Analysis of data at different local times reveals that the temperatures an…
The middle infrared (MIR) channel of the Atmospheric Chemistry Suite (ACS) instrument onboard the ExoMars Trace Gas Orbiter (TGO) ESA-Roscosmos mission has performed Solar occultation measurements of the Martian atmosphere in the 2.3-4.2 $μ$m spectral range since March 2018, which now covers two Martian Years (MY). We use the methodology previously developed for the study of the MY 34 Global Dust Storm (GDS) (Stcherbinine et al., 2020) to monitor the properties (effective radii, extinction, altitude) of the Martian water ice clouds over the first two Martian years covered by ACS-MIR. The obser…
Feasibility assessment of optical communications between ground and satellite on Mars through the simulation of atmospheric effects on signal quality leading to a proposal for a new communications network architecture during extreme weather
We report on the interannual variability of the atmospheric ice/dust cycle in the Martian polar regions for Mars Years 28-30. We used CRISM emission phase function measurements to derive atmospheric dust optical depths and data from the MARCI instrument to derive atmospheric water ice optical depths. We have used autocorrelation and cross correlation functions in order to quantify the degree to which dust and ice are correlated throughout both polar regions during Mars Years 28-29. We find that in the south polar region, dust has the tendency to "self clear", demonstrated by negative autocorre…
Towards a Foundation Model for the Martian Atmosphere
Earth System Science Center, University of Alabama in Huntsville（阿拉巴马大学亨茨维尔分校地球系统科学中心）；NASA Marshall Space Flight Center（美国宇航局马歇尔空间飞行中心）；Department of Electrical & Computer Engineering, Colorado State University（科罗拉多州立大学电气与计算机工程系）；Science and Technology Institute/Universities Space Research Association (USRA)（科学与技术研究所/大学空间研究协会）；Department of Computer Science, The University of Manchester（曼彻斯特大学计算机科学系）；School of Computer Science, University of Liverpool（利物浦大学计算机科学学院）；Center for Space Sciences and Technology, University of Maryland, Baltimore County（马里兰大学巴尔的摩分校空间科学与技术中心）；NASA Goddard Space Flight Center（美国宇航局戈达德空间飞行中心）；Center for Research and Exploration in Space Science and Technology, NASA/GSFC（空间科学与技术研究与探索中心，NASA/GSFC）；IBM Research（IBM研究院）
Atmospheric dust plays an important role on the terrestrial climate, regulating the amount of solar radiation coming to the surface, affecting the development and the life time of the clouds and providing fundamental nutrients to the growth of the terrestrial and oceanic biomes. On Mars, the global effect of dust is even stronger due to the widespread presence of sources and the lack of vegetation and oceans able to mitigate its contribution. The DREAMS station and the Dust Complex, on board of the ExoMars 2016 and 2020 mission respectively, have been specifically developed for the study of th…
Dust aerosol plays a fundamental role in the behavior and evolution of the Martian atmosphere. The first five Mars years of Mars Exploration Rover data provide an unprecedented record of the dust load at two sites. This record is useful for characterization of the atmosphere at the sites and as ground truth for orbital observations. Atmospheric extinction optical depths have been derived from solar images after calibration and correction for time-varying dust that has accumulated on the camera windows. The record includes local, regional, and globally extensive dust storms. Comparison with con…
