Breeding vectors and predictability in the Oxford Mars GCM

A breeding vectors approach is used to study the intrinsic predictability of the Martian atmosphere using the Oxford Mars General Circulation Model (MGCM). The approach, described in detail below, is first tested using a terrestrial general circulation model, the United Kingdom Meteorological Office’s Unified Model (UM), and results show growing modes of instability at mid to high latitudes on spatial scales of less than 1,000km, in qualitative agreement with previous studies performed using terrestrial models. For the Martian atmosphere, and in the absence of radiatively active dust transport (so using a typical background dust distribution for each time of year), the technique reveals model states with approximately zero growth factors, and modes of instability on relatively large (up to 5,000km) spatial scales. The implications of this for the predictability of the Martian atmosphere and for the usage of ensemble forecasting methods on Mars are also discussed.