Hydrogen escape from Mars is driven by seasonal and dust storm transport of water

Mars has lost most of its once-abundant water to space, leaving the planet cold and dry. In standard models, molecular hydrogen produced from water in the lower atmosphere diffuses into the upper atmosphere where it is dissociated, producing atomic hydrogen, which is lost. Using observations from the Neutral Gas and Ion Mass Spectrometer on the Mars Atmosphere and Volatile Evolution spacecraft, we demonstrate that water is instead transported directly to the upper atmosphere, then dissociated by ions to produce atomic hydrogen. The water abundance in the upper atmosphere varied seasonally, peaking in southern summer, and surged during dust storms, including the 2018 global dust storm. We calculate that this transport of water dominates the present-day loss of atomic hydrogen to space and influenced the evolution of Mars’ climate.

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The Spatial and Temporal Probability of Dust Storm Activity in Chryse, One of the Tentative Landing Areas of Tianwen-1 Mission

10.21203/rs.3.rs-41993/v1 ◽

2020 ◽

Author(s):

Bo Li ◽

Jiang Zhang ◽

Zongyu Yue ◽

Peiwen Yao ◽

Chenfan Li ◽

...

Keyword(s):

Dust Storm ◽

Dust Storms ◽

The Arctic ◽

Atmospheric Conditions ◽

Polar Ice ◽

Storm Activity ◽

Mars Atmosphere ◽

Ice Cap ◽

Activity Frequency ◽

Temporal And Spatial

Abstract Dust storms, observed in all seasons, are among the most momentous Mars atmosphere activities. The Entry-Descent-Landing (EDL) activity of a Martian landing mission is influenced by local atmospheric conditions, especially the dust storm activity probability. It is of great significance to know well the dust storm situation that China's first Mars mission (Tianwen-1) may encounter in EDL season in the Chryse area, one of the tentative landing areas. Firstly, based on four Martian years’ Mars Orbiter Camera (MOC) Mars Daily Global Maps (MDGMs), 1172 dust storms were identified within Chryse’s 1600 km radius ring with their shape parameters extracted, including center, range and area. Secondly, the daily mean dust storm probability was calculated binned by 1° of solar longitude in the Chryse area during EDL season. Dust storm activity frequency was closely interrelated with the seasonal ebb and flow of the arctic polar ice cap, consequently, most of dust storms occurring in either the cap’s grow or the recession. The dust storm activity in the Chryse area mainly came from the northern polar cap region, Acidalia and Chryse, with some contribution from the southern hemisphere (Argyre and Bosprous) northward. Thirdly, we divided the Chryse area into many square grids of 0.5° and computed the average occurrence probability of dust storm in each grid during EDL season. The dust storm activity probability in space was also in-homogeneous, low in the west and south but high in the east and north, which was mainly affected by three factors: topography, the origin and the path of dust storm sequence. Based on Empirical orthogonal function (EOF) analysis, of the storms in the Chryse area we’ve discovered, 40.5% are cap-edge storms in the northern hemisphere and 17.5% are textured dust storms. Finally, according to the temporal and spatial probability of dust storm activity in the Chryse area during EDL season, we held that the preferred landing time of the Tianwen-1 mission in 2021 was in Ls=18°-65° and three preferred landing areas were selected with low dust storm probability.

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Estimates of non-thermal atmospheric loss of exoplanet GJ 436b due to dissociation processes H2

Астрономия и исследование космического пространства: Всероссийская с международным участием научная конференция студентов и молодых ученых, посвященная памяти Полины Евгеньевны Захаровой ◽

10.15826/b978-5-7996-3229-8.17 ◽

2021 ◽

Author(s):

A. A. Avtaeva ◽

◽

V. I. Shematovich ◽

◽

Keyword(s):

Energy Spectrum ◽

Kinetic Energy ◽

Uv Radiation ◽

Atomic Hydrogen ◽

Molecular Hydrogen ◽

Upper Atmosphere ◽

Hydrogen Atoms ◽

Thermal Escape ◽

Atmospheric Loss

The contribution of the processes of dissociation of molecular hydrogen by hard ultraviolet (UV) radiation and the accompanying flux of photoelectrons to the formation of the fraction of suprathermal atomic hydrogen in the transition H2 −→ H region and the formation of the non-thermal escape flux from the extended upper atmosphere of the exoplanet — hot neptune GJ 436b — is estimated. The rate of formation and the energy spectrum of hydrogen atoms formed with an excess of kinetic energy during the dissociation of H2 are calculated.

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Variations in the Ionospheric Peak Altitude at Mars in Response to Dust Storms

10.17077/pp.005131 ◽

2019 ◽

Cited By ~ 1

Author(s):

Z Girazian ◽

Z Luppen ◽

D D Morgan ◽

F Chu ◽

L Montabone ◽

...

Keyword(s):

Solar Cycle ◽

Zenith Angle ◽

Dust Storm ◽

Observational Studies ◽

Solar Zenith Angle ◽

Dust Storms ◽

Upper Atmosphere ◽

Mars Express

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). We find that the peak altitude increased during regional dust storms in MY 27 and MY 33, and during the global dust storm in MY 28. In contrast, we find that the peak altitude did not increase during regional dust storms in MY 29 and MY 32, nor during the global dust storm in MY 34. Our results suggest that the response of the upper atmosphere and ionosphere to dust storms is dependent on several factors, including latitude, solar zenith angle, solar cycle conditions, and the magnitude of the dust storm.

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Dust grains fall from Saturn’s D-ring into its equatorial upper atmosphere

Science ◽

10.1126/science.aat2236 ◽

2018 ◽

Vol 362 (6410) ◽

pp. eaat2236 ◽

Cited By ~ 24

Author(s):

D. G. Mitchell ◽

M. E. Perry ◽

D. C. Hamilton ◽

J. H. Westlake ◽

P. Kollmann ◽

...

Keyword(s):

Molecular Hydrogen ◽

Upper Atmosphere ◽

Lower Atmosphere ◽

Dust Grains ◽

Dust Transport ◽

Imaging Instrument ◽

Cassini Spacecraft

The sizes of Saturn’s ring particles range from meters (boulders) to nanometers (dust). Determination of the rings’ ages depends on loss processes, including the transport of dust into Saturn’s atmosphere. During the Grand Finale orbits of the Cassini spacecraft, its instruments measured tiny dust grains that compose the innermost D-ring of Saturn. The nanometer-sized dust experiences collisions with exospheric (upper atmosphere) hydrogen and molecular hydrogen, which forces it to fall from the ring into the ionosphere and lower atmosphere. We used the Magnetospheric Imaging Instrument to detect and characterize this dust transport and also found that diffusion dominates above and near the altitude of peak ionospheric density. This mechanism results in a mass deposition into the equatorial atmosphere of ~5 kilograms per second, constraining the age of the D-ring.

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Impact of atmospheric gravity waves on the Martian global water cycle during dust storms

10.5194/egusphere-egu21-5562 ◽

2021 ◽

Author(s):

Dmitry Shaposhnikov ◽

Alexander Medvedev ◽

Alexander Rodin ◽

Paul Hartogh

Keyword(s):

Water Vapor ◽

Gravity Waves ◽

Dust Storm ◽

Water Cycle ◽

Dust Storms ◽

Upper Atmosphere ◽

Atmospheric Gravity Waves ◽

Global Water Cycle ◽

Atmospheric Gravity ◽

Global Water

<p>Effects of atmospheric gravity waves (GWs) on the global water cycle in the middle and high atmosphere of Mars during the global dust storms (Martian years 28 and 34) have been studied for the first time using a general circulation model. Dust storm simulations were compared with those utilizing the climatological distribution of dust in the absence of a GW parameterization. The dust storm scenarios are based on the observations of the dust optical depth by the Mars Climate Sounder instrument on board Mars Reconnaissance Orbiter. The simulations show that accounting for the influence of GWs leads to a change in the concentration of water vapor in the thermosphere. The most significant effect of GWs is twofold. First, cooling of the thermosphere at the poles leads to a decrease in the water vapor abundance during certain periods. Second, heating in the regions representing the main channels of water supply to the upper atmosphere (the so-called water "pump" mechanism) increases, on the contrary, its concentration. Since the temperature increase provides more intensive atmospheric mixing, and also expands the supply channel through an increase in saturation pressure. The dynamic balance of these basic mechanisms drives the changes in the distribution of water vapor in the upper atmosphere. Dust storms enhance pumping of water vapor into the upper atmosphere. Seasonal differences in the storm occurrences in different years allow for tracking the paths of water vapor transport to the upper atmosphere.</p>

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Dust storm activity in Tianwen-1 mission’s tentative landing area (Chryse) ： MGS-MOC observations from Mars year 24-28

10.21203/rs.3.rs-41993/v2 ◽

2020 ◽

Author(s):

Bo Li ◽

Peiwen Yao ◽

Jiang Zhang ◽

Zongyu Yue ◽

Chenfan Li ◽

...

Keyword(s):

Dust Storm ◽

Dust Storms ◽

The Arctic ◽

Atmospheric Conditions ◽

Polar Ice ◽

Storm Activity ◽

Mars Atmosphere ◽

Ice Cap ◽

Activity Frequency ◽

Temporal And Spatial

Abstract Dust storms, observed in all seasons, are among the most momentous Mars atmosphere activities. The Entry-Descent-Landing (EDL) activity of a Martian landing mission is influenced by local atmospheric conditions, especially the dust storm activity probability. It is of great significance to know well the dust storm situation that China's first Mars mission (Tianwen-1) may encounter in EDL season in the Chryse landing area, one of the tentative landing areas. Firstly, based on four Martian years’ Mars Orbiter Camera (MOC) Mars Daily Global Maps (MDGMs), 1172 dust storms were identified within Chryse’s 1600 km radius ring with their shape parameters extracted, including center, range and area. Secondly, the daily mean dust storm probability was calculated binned by 1° of solar longitude in the Chryse landing area during EDL season. Dust storm activity frequency was closely interrelated with the seasonal ebb and flow of the arctic polar ice cap, consequently, most of dust storms occurring in either the cap’s grow or the recession phase. The dust storm activity in the Chryse landing area mainly came from the northern polar cap region, Acidalia and Chryse, with some contribution from the southern hemisphere (Argyre and Bosporos) northward. Thirdly, we divided the Chryse landing area into many square grids of 0.5° and computed the average occurrence probability of dust storm in each grid during EDL season. The dust storm activity probability in space was also in-homogeneous, low in the west and south but high in the east and north, which was mainly affected by the origin and the path of dust storm sequence. Finally, according to the temporal and spatial probability of dust storm activity in the Chryse landing area during EDL season, we held that the preferred landing time of the Tianwen-1 mission in 2021 was in Ls=18°-65° and three preferred landing areas were selected with low dust storm probability.

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Dust Transport from Inland Australia and Its Impact on Air Quality and Health on the Eastern Coast of Australia during the February 2019 Dust Storm

Atmosphere ◽

10.3390/atmos12020141 ◽

2021 ◽

Vol 12 (2) ◽

pp. 141

Author(s):

Emilie Aragnou ◽

Sean Watt ◽

Hiep Nguyen Duc ◽

Cassandra Cheeseman ◽

Matthew Riley ◽

...

Keyword(s):

Air Quality ◽

Dust Storm ◽

New South ◽

New South Wales ◽

The State ◽

Dust Storms ◽

Eastern Coast ◽

Storm Event ◽

South Wales ◽

Dust Storm Event

Dust storms originating from Central Australia and western New South Wales frequently cause high particle concentrations at many sites across New South Wales, both inland and along the coast. This study focussed on a dust storm event in February 2019 which affected air quality across the state as detected at many ambient monitoring stations in the Department of Planning, Industry and Environment (DPIE) air quality monitoring network. The WRF-Chem (Weather Research and Forecast Model—Chemistry) model is used to study the formation, dispersion and transport of dust across the state of New South Wales (NSW, Australia). Wildfires also happened in northern NSW at the same time of the dust storm in February 2019, and their emissions are taken into account in the WRF-Chem model by using Fire Inventory from NCAR (FINN) as emission input. The model performance is evaluated and is shown to predict fairly accurate the PM2.5 and PM10 concentration as compared to observation. The predicted PM2.5 concentration over New South Wales during 5 days from 11 to 15 February 2019 is then used to estimate the impact of the February 2019 dust storm event on three health endpoints, namely mortality, respiratory and cardiac disease hospitalisation rates. The results show that even though as the daily average of PM2.5 over some parts of the state, especially in western and north western NSW near the centre of the dust storm and wild fires, are very high (over 900 µg/m3), the population exposure is low due to the sparse population. Generally, the health impact is similar in order of magnitude to that caused by biomass burning events from wildfires or from hazardous reduction burnings (HRBs) near populous centres such as in Sydney in May 2016. One notable difference is the higher respiratory disease hospitalisation for this dust event (161) compared to the fire event (24).

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