This computation involved: Met Office Africa Limited Area L70 Model (Africa-LAM) deployed on Met Office supercomputer (Exeter). The Africa Limited Area Model is a configuration of the Met Office Unified Model, which is a non-hydrostatic finite difference model with height as the vertical coordinate. It uses the full equations with virtually no approximations. Horizontal resolution is 0.11x0.11 degree (12km x 12km). Model has 70 levels.
|Previously used record indentifiers:||
More Information (under review)
The horizontal grid is square, consisting of 500 rows by 768 columns which span the latitude range 10° S to 45° N and the longitude range 20.0° W to 62° E. The horizontal resolution is 0.11° (approximately 12 km). The time-step is 4 minutes.
There are 70 levels in the vertical. These follow the terrain at the surface but level out to constant heights further up.
The boundary conditions are provided by the Met Office global model. They are applied in an ten-point rim around the edge of the area which is visible as a discontinuity in some of the fields.
The sea-surface temperature is held constant throughout the course of a run. Lakes are given surface temperatures equal to that of their nearest sea-point.
The model does not use diffusion.
|Grid-points:||768 x 500|
|Horizontal Resolution:||0.11° x0.11° (12 km x 12 km)|
|Unrotated pole:||90° N 180° W|
|1st point (lat, lon):|
|Vertical Levels:|| 70
50 BL levels
|Model Lid:||80 km|
|Model Timestep:||4 minutes|
|Radiation Timestep:||1 hour|
|Main Forecast Time:||06Z, 18Z|
|Data Assimilation:||Continuous 3D-Var (window T-3→T+3)|
|Driving Model:||Global Model|
|Reconfigure from global cycle:||06Z|
|LBCs:||3-hourly from T-3;
7 point halo; 10 point rim (weights, 1,1,1,1,1,1,1,0.75,0.5,0.25)
|Dates:||from 15th March 2011|
As the global model increases in resolution (expected to be 20 or 16km around the end of 2011), the value of running a globally-driven 12km LAM is questionable. Once global resolution has increased, regional 12km models will be replaced by select kilometre-scale domains to focus on greater local detail. With this in mind, and to demonstrate a capability to advise on hazards around the Lake Victoria area, a 4km Lake Victoria domain will be developed for implementation at PS27.
The Africa LAM was developed by Luke Jones (Met Office).
More details to follow