scholarly journals General circulation modeling of the Martian upper atmosphere during global dust storms

2013 ◽  
Vol 118 (10) ◽  
pp. 2234-2246 ◽  
Author(s):  
Alexander S. Medvedev ◽  
Erdal Yiğit ◽  
Takeshi Kuroda ◽  
Paul Hartogh
Keyword(s):  
General Circulation ◽  
Dust Storms ◽  
Upper Atmosphere ◽  
Circulation Modeling

scholarly journals Modeling dust emission response to MIS 3 millennial climate variations from the perspective of East European loess deposits

2013 ◽  
Vol 9 (1) ◽  
pp. 143-185 ◽  
Author(s):  
A. Sima ◽  
M. Kageyama ◽  
D.-D. Rousseau ◽  
G. Ramstein ◽  
Y. Balkanski ◽  
...  
Keyword(s):  
North Atlantic ◽  
General Circulation ◽  
Reference Site ◽  
Dust Emission ◽  
Dust Storms ◽  
Surface Model ◽  
Climate Signal ◽  
The North ◽  
Loess Deposits ◽  
The North Atlantic

Abstract. European loess sequences of the last glacial period (~ 100–15 kyr BP) show periods of strong dust accumulation alternating with episodes of reduced sedimentation, favoring soil development. In the western part of the loess belt centered around 50° N, these variations appear to have been caused by the North Atlantic rapid climate changes: the Dansgaard-Oeschger (DO) and Heinrich (H) events. It has been recently suggested that the North-Atlantic climate signal can be detected further east, in loess deposits from Stayky (50° 05.65' N, 30° 53.92' E), Ukraine. Here we use climate and dust emission modeling to investigate this data interpretation. We focus on the areas north and northeast of the Carpathians, where loess deposits can be found, and the corresponding main dust sources must have been located as well. The simulations, performed with the LMDZ atmospheric general circulation model and the ORCHIDEE land-surface model, represent a Greenland stadial, a DO interstadial and an H event respectively. Placed in Marine Isotope Stage 3 (~ 60–25 kyr BP) conditions, they only differ by the surface conditions imposed in the North Atlantic between 30° and 63° N. The main source for the loess deposits in the studied area is identified as a dust deflation band, with two very active spots located west–northwest from our reference site. Emissions only occur between February and June. Differences from one deflation spot to another, and from one climate state to another, are explained by analyzing the relevant meteorological and surface variables. Over most of the source region, the annual emission fluxes in the "interstadial" experiment are 30 to 50% lower than the "stadial" values; they would only be about 20% lower if the inhibition of dust uplift by the vegetation were not taken into account. Assuming that lower emissions result in reduced dust deposition leads us to the conclusion that the loess-paleosol stratigraphic succession in the Stayky area reflects indeed North-Atlantic millennial variations. In the main deflation areas of Western Europe, the vegetation effect alone determined most of the ~ 50% stadial-interstadial flux differences. Even if its impact in Eastern Europe is less pronounced, this effect remains a key factor in modulating aeolian emissions at millennial timescale. Conditions favorable to initiating particularly strong dust storms within a few hundred kilometers upwind from our reference site, simulated in the month of April of the "H event" experiment, support the identification of H events as layers of particularly coarse sedimentation in some very detailed profiles.

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

Science ◽  
2020 ◽  
Vol 370 (6518) ◽  
pp. 824-831
Author(s):  
Shane W. Stone ◽  
Roger V. Yelle ◽  
Mehdi Benna ◽  
Daniel Y. Lo ◽  
Meredith K. Elrod ◽  
...  
Keyword(s):  
Dust Storm ◽  
Atomic Hydrogen ◽  
Molecular Hydrogen ◽  
Dust Storms ◽  
Upper Atmosphere ◽  
Lower Atmosphere ◽  
Mars Atmosphere ◽  
Water Abundance ◽  
Neutral Gas ◽  
Standard Models

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.

From cold to warm gas giants: A three-dimensional atmospheric general circulation modeling

Icarus ◽  
2013 ◽  
Vol 225 (1) ◽  
pp. 228-235 ◽  
Author(s):  
Alexander S. Medvedev ◽  
Jisesh Sethunadh ◽  
Paul Hartogh
Keyword(s):  
General Circulation ◽  
Three Dimensional ◽  
Atmospheric General Circulation ◽  
Circulation Modeling

scholarly journals Influence of gravity waves on the climatology of high-altitude Martian carbon dioxide ice clouds

2018 ◽  
Author(s):  
Erdal Yiğit ◽  
Alexander S. Medvedev ◽  
Paul Hartogh
Keyword(s):  
Carbon Dioxide ◽  
High Altitude ◽  
Gravity Waves ◽  
General Circulation ◽  
Middle Atmosphere ◽  
Circulation Model ◽  
Upper Atmosphere ◽  
Cloud Formation ◽  
Ice Clouds ◽  
Ice Cloud

Abstract. Carbon dioxide (CO2) ice clouds have been routinely observed in the middle atmosphere of Mars. However, there are still uncertainties concerning physical mechanisms that control their altitude, geographical, and seasonal distributions. Using the Max Planck Institute Martian General Circulation Model (MPI-MGCM), incorporating a state-of-the-art whole atmosphere subgrid-scale gravity wave parameterization (Yiğit et al., 2008), we demonstrate that internal gravity waves generated by lower atmospheric weather processes have wide reaching impact on the Martian climate. Globally, GWs cool the upper atmosphere of Mars by ~10 % and facilitate high-altitude CO2 ice cloud formation. CO2 ice cloud seasonal variations in the mesosphere and the mesopause region appreciably coincide with the spatio-temporal variations of GW effects, providing insight into the observed distribution of clouds. Our results suggest that GW propagation and dissipation constitute a necessary physical mechanism for CO2 ice cloud formation in the Martian upper atmosphere during all seasons.

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