A Thermal Plume Model for the Martian Convective Boundary Layer

TL;DR

This paper adapts a thermal plume model from Earth to Mars to improve the representation of turbulent boundary layer processes in climate models, validated against lander data and capable of estimating key turbulent quantities.

Contribution

The paper introduces a modified thermal plume model specifically for Mars, enhancing the physical realism of PBL parameterizations in climate models.

Findings

The Martian thermal plume model reproduces the daytime PBL structure on Mars.

The model provides estimates of turbulent quantities like PBL height and plume velocity.

Validation against lander data supports the model's accuracy.

Abstract

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.