# Re: [netcdf-java] netCDF CDM grid with ensemble axis

```Don,

Just a warning.

```
The dimension order is not trivial for the CDM. For the time dimesion it could be has a different meaning.
```
In my example
float tas(ensemble=5, time1=121, height=1, lat=126, lon=201);

```
It would be interpreted (implicitly) as Time coordinate axis (forecast time).
```
float Total_precipitation(time=1, ens=11, lat=27, lon=51);

```
It would be interpreted as RunTime coordinate axis. The CDM has the concept of 2D time coordinates, and the order for dimensions are non-trivial.
```
Antonio

--
Antonio S. Cofiño
Grupo de Meteorología de Santander
Ciencias de la Computación
http://www.meteo.unican.es

El 06/11/2013 16:24, Don Murray (NOAA Affiliate) escribió:
```
```All-

```
This provides an example of the different ways that an ensemble dimension can be used and that the CDM can handle. For Antonio's example, the dimension ordering is:
```
float tas(ensemble=5, time1=121, height=1, lat=126, lon=201);
:_CoordinateAxes = "ensemble time1 height lat lon ";
:standard_name = "air_temperature";
:long_name = "Surface air temperature";
:units = "Celsius";

with ensemble as the leftmost dimension

In the ensemble files I generate, they are:

float Total_precipitation(time=1, ens=11, lat=27, lon=51);
:_FillValue = 9999.0f; // float
:units = "kg m-2";
```
:long_name = "Total_precipitation_Accumulation (Accumulation for Mixed Intervals) @ surface";
```
I put time in the leftmost dimension.

```
The nice thing is that the CDM does not care! You can structure it according to your needs.
```
Don

On 11/5/13 12:59 PM, Cofiño Gonzalez, Antonio Santiago wrote:
```
```Roland,

This is an example with Ensemble coordinate axis

```
http://www.meteo.unican.es/thredds/catalog/WRFUC/2013110412/catalog.html?dataset=OPERWRF12DatasetScan/2013110412/oper_gfs_mgrama_2013110412_d02.ncml
```
Antonio S. Cofiño
Santander Meteorology Group
University of Cantabria

El 05/11/2013, a las 16:45, "Roland Schweitzer - NOAA Affiliate"
```
<roland.schweitzer@xxxxxxxx <mailto:roland.schweitzer@xxxxxxxx>> escribió:
```
```
```Hi,

I see hints in the Java netCDF API that it can understand a grid that
has an ensemble axis.  What's not clear to me is how one constructs a
netCDF data source (either in the file or via some sort of TDS
aggregation) that represents the ensemble.  The CF conventions
document doesn't seem say anything about ensembles.

Google is failing me, can anybody offer some examples or documentation
links for data sources with an ensemble axis?

Thanks,
Roland
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