[ncl-talk] Using hyi2hyo to interpolate data from hybrid ERA-Interim to CAM4 L26

[Dennis Shea]

The email does not provide enough information for debugging.
I would suggest the following to facilitate debugging.


Since "horizontal resolution remains identical in this test",
pick one grid point

The reason for using {LAT:LAT},{LON:LON} is to force NCL to retain
dimensionality.
     x(time,lev,lat,lon)
If you use {LAT},{LON}, NCL will eliminate the 'degenerate' dimension
     x(time,lev)
-----------


              LAT =    30.0 ; wherever
              LON = 180.0

              x = f->ERAI(:,:,{LAT:LAT},{LON:LON})  ; force NCL to retain
dimensionality
              printVarSummary(x)   ; x(time,level,1,1)

              ps = f->PSFC(:,{LAT:LAT},{LON:LON})  ; force NCL to retain
dimensionality
              printVarSummary(ps)

       *system*
<https://www.ncl.ucar.edu/Document/Functions/Built-in/system.shtml>("/bin/rm
-f test_hyi2hyo.nc <http://test.nc>")    ; remove any pre-existing
file
       ncdf = *addfile*
<https://www.ncl.ucar.edu/Document/Functions/Built-in/addfile.shtml>("test_hyi2hyo.nc
<http://test.nc>" ,"c")  ; open output netCDF file

    ;===================================================================
    ; create global attributes of the file (optional)
    ;===================================================================
       fAtt               = True            ; assign file attributes
       fAtt at title         = "TEST NCL HYI2HYO: ERA-INTERIM grid point"
       fAtt at source_file   =  "original-file.nc"
       fAtt at Conventions   = "None"
       fAtt at creation_date = *systemfunc*
<https://www.ncl.ucar.edu/Document/Functions/Built-in/systemfunc.shtml>
("date")
       *fileattdef*
<https://www.ncl.ucar.edu/Document/Functions/Built-in/fileattdef.shtml>(
ncdf, fAtt )            ; copy file attributes
       *filedimdef*
<https://www.ncl.ucar.edu/Document/Functions/Built-in/filedimdef.shtml>(
ncdf,"time",-1,True)

    ;===================================================================
    ; output variables directly; NCL will call appropriate functions
    ; to write the meta data associated with each variable
    ;===================================================================
       ncdf->hya_erai = hya_erai                  ; 1D
       ncdf->hyb_erai = hyb_erai                  ; 1D
       ncdf->hya_cam  = hya_cam                   ; 1D
       ncdf->hyb_cam  = hyb_cam                   ; 1D

       ncdf->X_ERAI   = x                         ; 4D
       ncdf->PS_ERAI  = ps                        ; 3D

===

You can send the file and a *clean* simple version of your test script.





On Mon, Mar 23, 2015 at 2:55 PM, Mao-Lin Shen <maolin.shen at gfi.uib.no>
wrote:

> Hi,
>
>
> I interpolated data from hybrid ERA-Interim to CAM's hybrid level for
> nudging.
> But we found a big difference in between when we compared the data on
> pressure level.
>
> The results show in bellow.
>
> Left panel is the results applying hyi2hyo to get temperature on CAM's
> hybrid level first and then using vinth2p to get temperature on pressure
> level.
>
> Right panel shows the results interpolated from ERA-Interim by using
> vinth2p.
>
> Level       Temperature (Degree)    Temperature (Degree)
> (850hPa)  294.0318218618177      292.5374525210495
> (500hPa)  276.7536469179544      268.8364571841531
> (250hPa)  256.9609800328714      233.3842838572815
> (100hPa)  219.1232631977532      186.2120804720032
>
> Horizontal resolution remains identical in this test.
> The temperature are supposed to be identical, but it is not due to unclear
> issue.
> Does any one have similar problem?
> Or has idea how to tackle this issue?
>
>
>
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