Re: [ferret_users] Getting LAT and LON to be dimensions of a Variable

Thank you Ansley for the reply

Yes the Lat and Lon are the same for i and j respectively.

Here is the ncdump I did on my netcdf file:

The time is monthly data from 1999 to 2008

netcdf ROMS_SST{

dimensions:

M = 194 ;

L = 230 ;

TDIM = 120 ;

variables:

double lat(M, L) ;

lat:long_name = "latitude" ;

lat:units = "degN" ;

double lon(M, L) ;

lon:long_name = "longitude" ;

lon:units = "degE" ;

double SST(TDIM, M, L) ;

SST:long_name = "Sea Surface Temperature" ;

SST:units = "degC" ;

}

On Fri, Aug 8, 2014 at 1:51 AM, Ansley Manke <ansley.b.manke@xxxxxxxx> wrote:

Hi Molulaqhoo,
We have plans to handle data on "curvilienar grid" such as this transparently, using attributes in the dataset. This is not yet implemented. For now you need to do the 3-argument FILL command, with one exception. Some grids are defined this way but are in fact rectilinear. If the latitudes are the same at all values of i in the grid, and the longitudes are the same at all values of j in the grid, then it'd be a matter of defining 1-D coordinate axes; we can help you do that.

The axis that is being marked as a K axis doesn't have attributes that tell Ferret to mark it as a time axis. Is there a coordinate variable for the dimension of length 120 in the file? The Unix command ncdump would help us understand what is in the file:

> ncdump -h filename.nc

You could initialize the file in Ferret with the /ORDER= qualifier:

yes? use/order=xyt filename.nc
and then if the data should have a formatted time axis, you could use the DEFINE AXIS command, setting up a T axis of length 120, with the correct units and time origin, then put the data onto that axis with a command like:

yes? let new_sst = sst[gt=time_axis@asn]
-Ansley

On 8/7/2014 3:05 PM, Molulaqhooa Maoyi wrote:

Dear all

I am new into ferret and I have two questions:

I am battling to get the SST data to include LAT and LON dimension instead of them being separate. I would like to do a fill on the SST data without having to specify LAT and LON e.g fill SST[k=1], LON,LAT

name title I J K L M N

LAT latitude 1:230 1:194 ... ... ... ...

LON longitude 1:230 1:194 ... ... ... ...

SST Sea Surface Temperature 1:230 1:194 1:120 ... ... .

My second question is how to move a dimension from K to L on the SST variable.

Regards

Molulaqhooa
--

"Try and Fail than to Fail to Try" - Israel Maoyi

"Try and Fail than to Fail to Try" - Israel Maoyi