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The following is a table of GEM input vegetation classes and corresponding roughness lengths. For CLASS the roughness length is the height of the vegetation divided by 10.
In the geophysical fields the variable is called 'VF' but in model output it is called '2V'. Instead of having one field name for each surface (Vegetation) Fraction it was decided to use the same name, 'VF', but different levels to distinguish the different types. The fields themselves contain the fraction of the specific type.
| Arbitrary level # | Description | Z0 [m] |
|---|---|---|
| 1 | salt water, ocean | 0.001 |
| 2 | glacier | 0.0003 |
| 3 | inland lake | 0.001 |
| 4 | evergreen needle-leaf trees | 1.5 |
| 5 | evergreen broadleaf trees | 3.5 |
| 6 | deciduous needle-leaf trees | 1.0 |
| 7 | deciduous broadleaf trees | 2.0 |
| 8 | tropical broadleaf trees | 3.0 |
| 9 | drought deciduous trees | 0.8 |
| 10 | evergreen broadleaf shrubs | 0.05 |
| 11 | deciduous shrubs | 0.15 |
| 12 | thorn shrubs | 0.15 |
| 13 | short grass and forbs | 0.02 |
| 14 | long grass | 0.08 |
| 15 | crops | 0.08 |
| 16 | rice | 0.08 |
| 17 | sugar | 0.35 |
| 18 | maize | 0.25 |
| 19 | cotton | 0.1 |
| 20 | irrigated crops | 0.08 |
| 21 | urban | 1.35 |
| 22 | tundra | 0.01 |
| 23 | swamp | 0.05 |
| 24 | desert / bare soil | 0.05 |
| 25 | mixed wood forests | 1.5 |
| 26 | mixed shrubs | 0.05 |
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