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| Type (CMIP5) | Coordinate Name (CMIP5) | Dimension Names (CMIP5) | Axis | standard_name | long_name (CMIP5) | units (CF canonical units) | positive | valid_min (CMIP5) | valid_max (CMIP5) | bounds | Notes |
|---|---|---|---|---|---|---|---|---|---|---|---|
| double | lat | lat | Y | latitude | latitude | degrees_north | N/A | -90. | 90. | lat_bnds | Values (1x1deg grid) prescribed: [-89.5, -88.5 , ..., -0.5, 0.5 ... 89.5] |
| double | lon | lon | X | longitude | longitude | degrees_east | N/A | 0. | 360. | lon_bnds | Values (1x1deg grid) prescribed: center of 1-degree cells dimension lon=360 [0.5 , 1.5 , ..., 358.5, 359.5] |
| double | plev | plev | Z | air_pressure | pressure | Pa | down | N/A | N/A | This is also referred to as isobaric level by some tools [925., 850., 700., 500., 400., 300., 200., 100., 50., 30., 10.] | |
| double | depth | depth | Z | depth | depth | m | down | N/A | N/A | depth_bnds | Only used for soil model levels NOTE: Number and depth of levels is not prescribed by C3S |
| double | height | (scalar auxiliary coordinate) | Z | height | height | m | up or down | CMIP5: 2mtemp: 1. | CMIP5: 2mtemp: 10. | Used for single level fields (height, soil,SST) e.g. 2 m (for Temperature) | |
C3S: string
| realization | str31=31 | E | realization | realization | 1 | N/A | N/A | N/A | members are not a physical quantity. Realization is a discrete coordinate and the members its categorical values (ordered or non-ordered ones) SPECS approach: rXXiYYpZZ |
Note about interpolation, etcNOTE about the horizontal coordinates: The regridding procedure to provide the data in the 1-degree grid must take into account that the full definition of the gird cells is done by the cell boundaries (lat_bnds, lon_bnds)
Time Coordinates
| Type | Coordinate Name | Dimension Names | Axis | standard_name | long_name | calendar | units | bounds | Notes |
|---|---|---|---|---|---|---|---|---|---|
| double | reftime | N/A | N/A | forecast_reference_time | "Start date of the forecast" | gregorian | UDUNITS time units e.g. "hours since YYYY-MM-DD hh:mm:ss TZhh:TZmm" | N/A | In SPECS it is a "global_attribute" It has been additionally introduced here as a coordinate variable to ease future netCDF management (e.g. file merging) |
| double | leadtime | leadtime | N/A | forecast_period | "Time elapsed since the start of the forecast" | N/A | SPECS: days | leadtime_bnds | The interval of time between the forecast reference time and the valid time Boundaries not needed when this time coordinate is used for instantaneous values (note that "time:point" is used as cell_method in those cases) When boundaries are required, the value of the coordinate must be in the centre of the correspondent time cell boundaries |
| double | time | leadtime | N/A | time | "Verification time of the forecast" | gregorian | SPECS: "days since 1850-01-01" C3S: requested units can be relaxed to equivalent time units | time_bnds | Time for which the forecast is valid Boundaries not needed when this time coordinate is used for instantaneous values (note that "time:point" is used as cell_method in those cases) When boundaries are required, the value of the coordinate must be in the centre of the correspondent time cell boundaries
|
NOTE: Definitions for "leadtime" and "time" have been taken from SPECS. The introduction of "reftime" as a variable has been adapted from SPECS global attribute description for the forecast reference time.
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| Warning |
|---|
"leadtime" has been selected as dimension (instead of "time") for both time and leadtime. That means "leadtime" is the coordinate and "time" is an auxiliary coordinate
|
Cell boundaries
As described in section 7.1 Cell Boundaries of CF convention.
| Info |
|---|
To represent cells we add the attribute |
| Bounds Name | Dimensions | Comments |
|---|---|---|
| time_bnds | leadtime, bnds | |
| Bounds Name | Dimensions | Comments |
| time_bnds | time, bnds | |
| leadtime_bnds | ||
| lat_bnds | lat, bnds | Values (1x1deg grid) prescribed: [-90., 89.], [-89., -88.], ... [89., 90.] |
| lon_bnds | lon, bnds | Values (1x1deg grid) prescribed: [0., 1.], [1., 2.], ... [359., 360.] |
| depth_bnds | depth,bnds | Should define the full vertical extent of the soil model layers |
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| attributes | |||||||
| name (CMIP5) | dimensions | standard_name | long_name (CMIP5) | units | coordinates | cell_methods | NOTES |
|---|---|---|---|---|---|---|---|
| zg | time,plev,lat,lon | geopotential_height | "Geopotential Height" | m | "time: point" C3S: required CF: recommended | ||
| ta | time,plev,lat,lon | air_temperature | "Air Temperature" | K | "time: point" C3S: required CF: recommended | ||
| hus | time,plev,lat,lon | specific_humidity | "Specific Humidity" | 1 | "time: point" C3S: required CF: recommended | ||
N/A in CMIP | time,plev,lat,lon | atmosphere_relative_vorticity |
N/A in CMIP | s-1 | "time: point" C3S: required CF: recommended | ||
N/A in CMIP | time,plev,lat,lon | divergence_of_wind |
N/A in CMIP | s-1 | "time: point" C3S: required CF: recommended | ||
| ua | time,plev,lat,lon | x_wind | "Eastward Wind" | m s-1 | "time: point" C3S: required CF: recommended | ||
| va | time,plev,lat,lon | y_wind | "Northward Wind" | m s-1 | "time: point" C3S: required CF: recommended | ||
When boundaries are required, the value of the coordinate must be in the centre of the correspondent time cell boundaries