Re: Ferret: A question about recognizing dimentions.

[Ansley Manke <ansley.b.manke@xxxxxxxx>]

Hi Jian,
Ferret looks for clues about the direction of a coordinate variable in the attributes of the coordinate variables. It uses the coordinate variable's name and its units to try to tell what direction the dimension has. If an axis has the "positive = up, or postitive = "down" attribute then it is detected as a Z axis.  If Ferret can't tell what direction the coordinate variable has, then it uses a default ordering. You can include the attributes "axis" or "coordinate_axis" to tell Ferret the direction of the dimension.

See "NetCDF, axis definition" in the Users Guide for a complete description of this.

Ansley


Jian Ma wrote:

Dear Ferreters,

 

I am using Fortran to write a netCDF file and Ferret to read and plot it. When I create a file with variable which has Y, Z, T coordinates, it works well.

 

name     title                             I         J         K         L
TEMP                                      ...       1:625     1:30      1:12

 

But if the variable has X, Z, T coordinates, a problem occurs.

 

name     title                             I         J         K         L

TEMP                                      1:721     1:30      ...       1:12

 

It was recognized as X, Y, T.

 

The netCDF file looks well in ncdump.

 

dimensions:
        time = 12 ;
        layer = 30 ;
        lon = 721 ;
variables:
        float lon(lon) ;
                lon:units = "degree_east" ;
        float temp(time, layer, lon) ;
                temp:missing_value = 1.70141e+038f ;
                temp:units = "Degree" ;
data:

...

 

I would appreciate very much if you can tell me how Ferret recognize the dimensions, and also to solve this problem. Should I just define all 4-dimensions with one of them having only one constant value? That seems a bit stupid.

 

Lots of thanks,

Jian

 

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Jian Ma

 

M. S. in Physical Oceanography
The First Institute of Oceanography
State Oceanic Administration
P. R. China

 

No. 6 Xian-Xia-Ling Road, Qingdao 266061
Tel: 86-532-8967401
Fax: 86-532-8967400
URL: www.fio.org.cn
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