The nighttime boundary layer of Mars as predicted by large-eddy simulations

Abstract

The Martian planetary boundary layer (PBL) drives the surface-atmosphere exchange processes such as the Martian dust cycle, which leads to strong atmospheric variations from diurnal to seasonal and inter-annual time scales [1]. The amount of dust lifted into the atmosphere and the vertical winds that balance the gravitational settling for the aerosols are affected by the turbulent mixing within the boundary layer. Several studies focused on the dynamics of the Martian PBL during daytime conditions [2,3]. During daytime conditions, the strong buoyancy caused by the vertical thermal gradient can generate turbulent mixing and initiate turbulence. On the other hand, the nighttime boundary layer is suggested to form under very weak turbulent mixing conditions. However, recent observations by the InSight lander showed unexpected turbulent signatures during nighttime conditions [4]. Nevertheless, lacking the observational datasets revealing the vertical variation of temperature and winds within the first kilometer of the Martian atmosphere, we do not fully understand the dynamics of the Martian boundary layer. To complement the limited observations on the Martian boundary-layer meteorology, high-resolution limited area models, so called large-eddy simulations (LES), are used. Here, we use the LES module of MarsWRF [3,5] to investigate the time and length scales of nighttime turbulence and possible large-scale atmospheric phenomena that can affect the near-surface nighttime meteorology. We present possible implications related to the Martian dust cycle.[1] Senel, C.B., Temel, O., Lee, C., Newman, C.E., Mischna, M.A., Muñoz‐Esparza, D., Sert, H. and Karatekin, Ö., 2021. Interannual, Seasonal and Regional Variations in the Martian Convective Boundary Layer Derived From GCM Simulations With a Semi‐Interactive Dust Transport Model. Journal of Geophysical Research: Planets, 126(10), p.e2021JE006965.[2] Spiga, A., Forget, F., Lewis, S.R. and Hinson, D.P., 2010. Structure and dynamics of the convective boundary layer on Mars as inferred from large‐eddy simulations and remote‐sensing measurements. Quarterly Journal of the Royal Meteorological Society: A journal of the atmospheric sciences, applied meteorology and physical oceanography, 136(647), pp.414-428.[3] Temel, O., Senel, C.B., Porchetta, S., Muñoz-Esparza, D., Mischna, M.A., Van Hoolst, T., van Beeck, J. and Karatekin, Ö., 2021. Large eddy simulations of the Martian convective boundary layer: towards developing a new planetary boundary layer scheme. Atmospheric Research, 250, p.105381.[4] Temel, O., Senel, C.B., Spiga, A., Murdoch, N., Banfield, D. and Karatekin, O., 2022. Spectral analysis of the Martian atmospheric turbulence: InSight observations. Geophysical Research Letters, 49(15), p.e2022GL099388.[5] Wu, Z., Richardson, M.I., Zhang, X., Cui, J., Heavens, N.G., Lee, C., Li, T., Lian, Y., Newman, C.E., Soto, A. and Temel, O., 2021. Large eddy simulations of the dusty Martian convective boundary layer with MarsWRF. Journal of Geophysical Research: Planets, 126(9), p.e2020JE006752.