195 research outputs found
A Thermal Plume Model for the Martian Convective Boundary Layer
The Martian Planetary Boundary Layer [PBL] is a crucial component of the
Martian climate system. Global Climate Models [GCMs] and Mesoscale Models [MMs]
lack the resolution to predict PBL mixing which is therefore parameterized.
Here we propose to adapt the "thermal plume" model, recently developed for
Earth climate modeling, to Martian GCMs, MMs, and single-column models. The aim
of this physically-based parameterization is to represent the effect of
organized turbulent structures (updrafts and downdrafts) on the daytime PBL
transport, as it is resolved in Large-Eddy Simulations [LESs]. We find that the
terrestrial thermal plume model needs to be modified to satisfyingly account
for deep turbulent plumes found in the Martian convective PBL. Our Martian
thermal plume model qualitatively and quantitatively reproduces the thermal
structure of the daytime PBL on Mars: superadiabatic near-surface layer, mixing
layer, and overshoot region at PBL top. This model is coupled to surface layer
parameterizations taking into account stability and turbulent gustiness to
calculate surface-atmosphere fluxes. Those new parameterizations for the
surface and mixed layers are validated against near-surface lander
measurements. Using a thermal plume model moreover enables a first order
estimation of key turbulent quantities (e.g. PBL height, convective plume
velocity) in Martian GCMs and MMs without having to run costly LESs.Comment: 53 pages, 21 figures, paper + appendix. Accepted for publication in
Journal of Geophysical Research - Planet
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