This study presents the development of a TKE-l parameterization of the
diffusion coefficients for the representation of turbulent diffusion in
neutral and stable conditions in large-scale atmospheric models. The
parameterization has been carefully designed to be completely tunable in
the sense that all adjustable parameters have been clearly identified
and their number minimized as much as possible to help the calibration
and to thoroughly assess the parametric sensitivity. We choose a mixing
length formulation that depends on both static stability and wind shear
to cover the different regimes of stable boundary layers. We follow a
heuristic approach for expressing the stability functions and turbulent
Prandlt number in order to guarantee the versatility of the scheme and
its applicability for planetary atmospheres composed of an ideal and
perfect gas such as that of Earth and Mars. Particular attention has
also been paid to the numerical stability at typical time steps used in
General Circulation Models. Test, parametric sensitivity assessment and
preliminary tuning are performed on single-column idealized simulations
of the weakly stable boundary layer. The robustness and versatility of
the scheme are also assessed through its implementation in the LMDZ
General Circulation Model and the Mars Planetary Climate Model and by
running simulations of the Antarctic and Martian nocturnal boundary
layers.