Modelling the dust-laden Martian boundary layer

The NASA/University of Arizona Phoenix mission is scheduled to land at 70 degrees North on Mars in late May. The MET package provided primarily by the Canadian Space Agency will include a vertically pointing dual wavelength lidar to study distributions of dust and cloud. In particular we plan to use the lidar returns to determine the depth of the afternoon boundary layer, on the assumption that there will be a significant drop in the dust concentration at that level.

The recent paper by Taylor et al (Boundary-Layer Meteorology, 125, 305-328) describes one approach to predicting boundary-layer depth based on separate models of diurnal cycles of the Martian boundary layer and of the transport, settling and diffusion of size distributed dust. The conclusion of that modelling study was that it would be possible to determine the boundary-layer depth both when dust was being advected into the region from dust storms initiated elsewhere or in strong wind situations, from dust raised locally. We also noted that “Further work is needed to couple the boundary-layer and dust models and to make quantitative comparisons with data to be collected during the Phoenix mission.”

In the present paper we have refined the dust optical properties and coupled the two models. While results are generally similar to those obtained with the uncoupled model we do see an increase in the maximum boundary-layer height from ~2.4km (uncoupled) to ~3km (coupled) in our reference case. While we are unlikely to have extensive data from the Phoenix lander in time for the June symposium we will present model calculations for a range of anticipated scenarios.