Model resolution
Figure 1: Mean center of layer heights in the Oslo CTM3, for L60 and L40 resolution. Vertical axes are height in km; left: 0–70km, right: 0–2km. (Click for larger picture.)
Vertical resolution
The Oslo CTM3 standard vertical resolution is 60 layers (L60), but can
also be run with our old 40 layer (L40) meteorological data. L40 is,
however, being phased out, so new L40 data will not be produced.
For L60 and L40, the sigma-pressure hybrid coordinates extend from
the surface up to 0.1hPa and 10hPa, respectively (mass center of
uppermost layer).
It is possible to reduce the number of layers by collapsing them, a
feature new to the Oslo CTM3.
The average center heights of the model layers are shown in Figure 1. In the tropopause region the vertical resolution varies between about 0.8km in high latitudes and about 1.2km in low latitudes.
Horizontal resolution
The Oslo CTM3 is available in different horizontal resolutions, depending on
the meteorological data.
The standard resolution is T42 (2.8125 x 2.8125 degrees), although higher
resolutions are also available or can be generated.
For L60 we have some T159 (1.125 x 1.125 degrees) data, and one year
of T319L60 (0.5625 x 0.5625 degrees), while for L40 we have a few years of
1x1 degrees data in addition to T42.
The native resolution of L60 data is T319, which is the highest resolution we can retrieve at the moment. Computationally, it will still be years before full chemistry can be simulated in T319.
Figure 2: The T42 (red) and T159 (blue) grids in the Oslo CTM3 (click for larger picture).