Structure and dynamics of the convective boundary layer on Mars as inferred from large‐eddy simulations and remote‐sensing measurements

Comment on ''Observing desert dust devils with a pressure logger" by Lorenz (2012) – insights on measured pressure fluctuations from large-eddy simulations

“…Fig. 2 in Spiga et al, 2010). Those convective cells are associated with fluctuations of surface pressure and horizontal wind ("gustiness") as is shown in Fig.…”

“…This stems from a similar physical cause in both situations; convective turbulent motions arise in the PBL, following unstable temperature gradients which develop near the surface heated by incoming sunlight. The differences between terrestrial and Martian PBLs described in Spiga et al (2010) affect PBL vertical structure and depth, but yield similar horizontal organization for both planets.…”

“…Here we base our discussions on Martian LES modeling described in Spiga et al (2010). The conclusions we draw from Martian LESs hold for the Earth as well; how daytime PBL convection is organized is qualitatively similar in Martian and arid terrestrial environments (Kanak, 2006).…”

“…To illustrate this, we carried out LESs in the same typical Martian conditions as in Fig. 1, except we prescribed a background wind of 10 and 20 m s −1 (again, we choose the case of Mars for convenience and proximity to our recent modeling work in Spiga et al (2010), but conclusions apply in terrestrial deserts too). LESs show that pressure maxima and minima associated with PBL convective cells are advected by background wind.…”

“…LESs are high-resolution numerical integrations of atmospheric fluid dynamics equations which resolve the turbulent transport by the largest PBL eddies and plumes (Lilly, 1962). LESs have been carried out for Earth (Kanak et al, 2000) and Mars (Michaels and Rafkin, 2004;Spiga et al, 2010). This high-resolution modeling technique unveils the three-dimensional structure of the convective PBL, which is hardly achieved through measurements.…”