A study of daytime convective vortices and turbulence in the martian Planetary Boundary Layer based on half-a-year of InSight atmospheric measurements and Large-Eddy Simulations - Institut Polytechnique de Paris Accéder directement au contenu
Article Dans Une Revue Journal of Geophysical Research. Planets Année : 2020

A study of daytime convective vortices and turbulence in the martian Planetary Boundary Layer based on half-a-year of InSight atmospheric measurements and Large-Eddy Simulations

Résumé

Studying the atmospheric Planetary Boundary Layer (PBL) is crucial to understand theclimate of a planet. The meteorological measurements by the instruments onboard InSightat a latitude of 4.5◦N make a uniquely rich dataset to study the active turbulent dynamics ofthe daytime PBL on Mars. Here we use the high-sensitivity continuous pressure, wind, tem-perature measurements in the first 400 sols of InSight operations (from northern late winterto midsummer) to analyze wind gusts, convective cells and vortices in Mars’ daytime PBL.We compare InSight measurements to turbulence-resolving Large-Eddy Simulations (LES).The daytime PBL turbulence at the InSight landing site is very active, with clearly identi-fied signatures of convective cells and a vast population of 6000 recorded vortex encounters,adequately represented by a power-law with a 3.4 exponent. While the daily variability ofvortex encounters at InSight can be explained by the statistical nature of turbulence, the sea-sonal variability is positively correlated with ambient wind speed, which is supported by LES.However, wind gustiness is positively correlated to surface temperature rather than ambientwind speed and sensible heat flux, confirming the radiative control of the daytime martianPBL; and fewer convective vortices are forming in LES when the background wind is doubled.Thus, the long-term seasonal variability of vortex encounters at the InSight landing site ismainly controlled by the advection of convective vortices by ambient wind speed. Typicaltracks followed by vortices forming in the LES show a similar distribution in direction andlength as orbital imagery.
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Dates et versions

hal-03155300 , version 1 (01-03-2021)

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A. Spiga, N. Murdoch, R. Lorenz, F. Forget, C. E Newman, et al.. A study of daytime convective vortices and turbulence in the martian Planetary Boundary Layer based on half-a-year of InSight atmospheric measurements and Large-Eddy Simulations. Journal of Geophysical Research. Planets, 2020, 126 (1), ⟨10.1029/2020JE006511⟩. ⟨hal-03155300⟩
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