Re: GCM output on i,j grid instead of lat,lon

Hi Mary,

Thanks very much for your reply. As it turns out, I have used the CICE
Tripole Grid example (last example here:
http://www.ncl.ucar.edu/Applications/ice.shtml) which seems to do the
trick for correctly plotting with the irregular ocean grid in the BNU
model. But just to answer your question, there is no additional attribute
called "coordinates" in the file. I had to use the t-grid cell area file
from the model output to get TLAT and TLON.

However, now I am running into an issue where the x and y axes of my plot
are automatically labeled as "cell index along first dimension" and "cell
index along second dimension". Is it possible to suppress these labels?
I have tried with the following but it doesn't do the trick:
  res@gsnLeftString = "" ; suppress automatic labels
  res@gsnRightString = ""

Thanks very much to anyone who can help out.
Best,
Mira

> Mira,
>
> It looks like the BNU model might have its data on a curvilinear grid.
>
> That is, the grid is defined by 2D lat/lon arrays, rather than by
> 1D lat/lon arrays (rectilinear). For curvlinear variables, you won't
> have the lat/lon arrays attached as coordinate arrays. You will
> have to read them in separately.
>
> Sometimes there's an additional attribute called "coordinates" attached
> to your variable that tells you what the name of the lat/lon variables are
> on the file.
>
> For example:
>
> float TEMP ( time, z_t, nlat, nlon )
> long_name : Potential Temperature
> units : degC
> coordinates : TLONG TLAT z_t time <-------
> cell_methods : time: mean
> _FillValue : 9.96921e+36
> missing_value : 9.96921e+36
>
> The above information tells me to look for TLONG and TLAT variables on the
> file.
>
> Does the "sicBNU_6070_rcp45" variable have any other attribute
> information other than what you included below? If so, look for
> an attribute called "coordinates", which then might give you
> the name of the lat/lon variables on the file to use.
>
> If this doesn't help, then can you provide us with a sample file?
>
> http://www.ncl.ucar.edu/report_bug.shtml#HowToFTP
>
> Thanks,
>
> --Mary
>
>
> On Jun 1, 2013, at 10:34 AM, Mira Berdahl wrote:
>
>> Hi everyone,
>>
>> I am experiencing a problem when plotting sea ice extent as a spaghetti
>> plot from one of the CMIP5 output models. It seems that the BNU model
>> is
>> on an i,j grid whereas all other models (that I have used at least) are
>> on
>> a lat,lon grid.
>>
>> So when I printVarSummary for the BNU variable I am trying to plot I
>> get:
>> Variable: sicBNU_6070_rcp45
>> Type: float
>> Total Size: 144000 bytes
>> 36000 values
>> Number of Dimensions: 2
>> Dimensions and sizes: [j | 100] x [i | 360]
>> Coordinates:
>> j: [101..200]
>> i: [1..360]
>> Number Of Attributes: 11
>> standard_name : sea_ice_area_fraction
>> long_name : Sea Ice Area Fraction
>> comment : fraction of grid cell covered by sea ice.
>>
>>
>>
>>
>> Whereas for the other models I get something like:
>>
>> Variable: sicMIROC_CHEM_6070_rcp45
>> Type: float
>> Total Size: 98304 bytes
>> 24576 values
>> Number of Dimensions: 2
>> Dimensions and sizes: [lat | 96] x [lon | 256]
>> Coordinates:
>> lat: [0.2790889739990234..89.14443969726562]
>> lon: [0.703125..359.296875]
>> Number Of Attributes: 11
>> standard_name : sea_ice_area_fraction
>> long_name : Sea Ice Area Fraction
>> comment : fraction of grid cell covered by sea ice.
>>
>>
>> When I try to make the spaghetti plot, it runs but gives a very wrong
>> looking result for the BNU model. The other models look good. I should
>> mention that the BNU output does indeed have lat and lon but as separate
>> variables. When I use ncview to look at the BNU data it looks fine, but
>> I
>> am assuming NCL is having problems since its dimensions are not lat,lon.
>> Is that right? Does anyone see a good way to work around this?
>>
>> Thanks in advance for any help or suggestions!
>> MB
>>
>>
>>
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Received on Mon Jun 3 10:43:07 2013