Dust plays a central role in the Martian climate, controlling much of its seasonal and interannual
\nvariability and occasionally giving rise to regional and even global dust storms. Despite several
\ndecades of observations, reproducing the Martian dust cycle realistically remains a major challenge
\nfor climate models.
\nThis seminar will present a new numerical model of the Martian dust cycle, based on Global
\nClimate Model simulations and incorporating, through parameterizations, several subgrid-scale
\nlifting processes that are poorly resolved by conventional models. Fast and computationally
\nefficient, this model makes it possible to simulate several centuries of Martian climate while
\nrepresenting the coupling between dust lifting, transport, surface reservoirs, and radiative
\nfeedbacks.
\nThe simulations realistically reproduce the observed seasonal dust cycle, the interannual alternation
\nbetween years with and without global dust storms, and the observed seasonality of global dust
\nstorms. They show that extreme local winds and the heterogeneous distribution of surface dust
\nreservoirs play a key role in controlling the Martian dust cycle.
\nThese results provide new insights into the mechanisms responsible for global dust storms and open
\nnew perspectives for Martian weather forecasting, as well as for the broader study of planetary
\nclimates.<\/p>\n
Le cycle de la poussi\u00e8re martienne : r\u00f4le des vents extr\u00eames locaux et des r\u00e9servoirs de surface
\nLa poussi\u00e8re joue un r\u00f4le central dans le climat martien, elle contr\u00f4le une grande partie de sa
\nvariabilit\u00e9 saisonni\u00e8re et interannuelle, et peut conduire certaines ann\u00e9es \u00e0 des temp\u00eates r\u00e9gionales,
\nvoire globales. Malgr\u00e9 plusieurs d\u00e9cennies d\u2019observations, reproduire de fa\u00e7on r\u00e9aliste le cycle de
\nla poussi\u00e8re martienne reste un d\u00e9fi majeur pour les mod\u00e8les climatiques.
\nCe s\u00e9minaire pr\u00e9sentera un nouveau mod\u00e8le num\u00e9rique du cycle de la poussi\u00e8re martienne, fond\u00e9
\nsur des simulations de mod\u00e8les de circulation g\u00e9n\u00e9rale et int\u00e9grant, sous forme param\u00e9tr\u00e9e,
\nplusieurs processus de soul\u00e8vement sous-maille mal r\u00e9solus par les mod\u00e8les classiques. Rapide et
\npeu co\u00fbteux en calcul, ce mod\u00e8le permet de simuler plusieurs si\u00e8cles martiens tout en repr\u00e9sentant
\nle couplage entre soul\u00e8vement, transport, r\u00e9servoirs de surface et r\u00e9troactions radiatives de la
\npoussi\u00e8re.
\nLes simulations reproduisent de fa\u00e7on r\u00e9aliste le cycle saisonnier observ\u00e9, l\u2019alternance interannuelle
\nentre ann\u00e9es avec et sans temp\u00eate globale, ainsi que la saisonnalit\u00e9 des temp\u00eates globales. Elles
\nmontrent que les vents extr\u00eames locaux et l\u2019h\u00e9t\u00e9rog\u00e9n\u00e9it\u00e9 des r\u00e9servoirs de poussi\u00e8re en surface
\njouent un r\u00f4le essentiel dans le contr\u00f4le du cycle de la poussi\u00e8re martienne.
\nCes r\u00e9sultats apportent un nouvel \u00e9clairage sur les m\u00e9canismes \u00e0 l\u2019origine des temp\u00eates globales et
\nouvrent des perspectives pour la pr\u00e9vision m\u00e9t\u00e9orologique martienne, ainsi que pour l\u2019\u00e9tude plus
\ng\u00e9n\u00e9rale des climats plan\u00e9taires.<\/p>\n","protected":false},"excerpt":{"rendered":"
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