Re: [ferret_users] projections and multiple input files

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

Hi ,
Your data is already what we call curvilinear data, where the longitude 
and latitude fields are defined by 2-dimensional variables. To use a map 
projection with this kind of grid, follow the instructions in the 
following FAQ. You are doing the correct thing with respect to the fact 
that the data is in different files, using the [d=1] on your variable 
sea_surface_temperature[d=1].

http://ferret.pmel.noaa.gov/Ferret/FAQ/graphics/mp_curvi_data.html

Ansley

Martinho MA wrote:
> Hello,
> I have two files, one includes sst and the other longitude and 
> latitude, see ncdump:
> >ncdump -h 200512271200.nc
> netcdf 200512271200 {
> dimensions:
>        time = 1 ;
>        depth = 1 ;
>        latitude = 1024 ;
>        longitude = 1024 ;
> variables:
>        short sea_surface_temperature(time, latitude, longitude) ;
>                sea_surface_temperature:long_name = "sea surface 
> temperature" ;
>                sea_surface_temperature:units = "K" ;
>                sea_surface_temperature:scale_factor = 0.01 ;
>                sea_surface_temperature:add_offset = 0.f ;
>                sea_surface_temperature:valid_min = 0s ;
>                sea_surface_temperature:valid_max = 32767s ;
>                sea_surface_temperature:missing_value = 32767s ;
>                sea_surface_temperature:_FillValue = 32767s ;
> ... etc     
> ncdump -h grid.nc
> netcdf grid {
> dimensions:
>        latitude = 1024 ;
>        longitude = 1024 ;
> variables:
>        float latitude(latitude, longitude) ;
>                latitude:long_name = "latitude" ;
>                latitude:units = "degrees_N" ;
>        float longitude(latitude, longitude) ;
>                longitude:long_name = "longitude" ;
>                longitude:units = "degrees_E" ;
> }
>
>
> to plot ssh I use fill sea_surface_temperature[d=1],longitude,latitude
>
> But now, I would like to use some map projection... I checked the 
> ferret demo:
> http://ferret.wrc.noaa.gov/Ferret/Demos/mp_demo/mp_demo.html
>
> SO, I think I should so:
> SET REGION/X=-15:-8/Y=35:45/l=1
> GO mp_lambert_cyl
> GO mp_aspect
> fill SEA_SURFACE_TEMPERATURE,LONGITUDE[d=1],latitude[d=1]
>
> This isnt working, and even without the projection, I got and error:
> fill SEA_SURFACE_TEMPERATURE,LONGITUDE[d=1],latitude[d=1]
> **ERROR: illegal limits: "SEA_SURFACE_TEMPERA..." is not in the range 
> X=-15:-8
>          Axis extremes are X=0.5:1024.5
>
> I guess this is because I have dimension longitude and latitude in my 
> sst variable, and then I want to use longitude and latitude from other 
> file.!?
> How can I solve this?
> I am quite a basic ferret user, and maybe the question is basic too...
>
> Thanks
> MMA