| 172 | |
| 173 | === Units Information === |
| 174 | |
| 175 | Translation of units depends on if the crs is geographic or projected |
| 176 | |
| 177 | For a geographic crs (grid_mapping_name = "latitude_longitude"), units are angular. GEOGCS contains a UNIT node which gives the conversion to radians. When the crs is in degrees the following node is used: UNIT["degree",0.0174532925199433]. For a more complete description, see CT 1.0 section "7.3.19 UNIT" |
| 178 | CF requires all value to be in degrees, which is specified in the dimension's units attribute ( lon:units = "degrees_east" / lat:units = "degrees_north" ), the udunits packages allows to transform from radians. |
| 179 | |
| 180 | For a projected crs, units are linear. PROJCS must contains a UNIT node which gives the conversion into meters. For example, if the units are in kilometers the following node is used: UNIT["kilometre",1000]]. |
| 181 | In CF, units are given in the dimension's units attribute (xc:units = "m"). |