[ncl-talk] sub: Regridding NARR data

[Dennis Shea]

I did not look closely at what I had done. I made a graphical mistake.
The attached is correct.

On Sun, Mar 1, 2020 at 8:25 PM Dennis Shea <shea at ucar.edu> wrote:

> The following ESMF example illustrates how to interpolate from a NARR grid
> to a rectilinear grid:
> *http://www.ncl.ucar.edu/Applications/ESMF.shtml*
> <http://www.ncl.ucar.edu/Applications/ESMF.shtml>
> ESMF_wgts_30.ncl
> ------------------------
> The ESMF software does NOT work with cartesian [projection] coordinates ['
> *x'* , '*y*'] which have units of meters.
>                     ; the following are not correct
>
>   lon2d    = f1[:]->x
>
>   lat2d    = f1[:]->y
>
>
> The ESMF software works with latitudes and longitudes.
>
> You should extract the latitudes and longitudes from the first file only:
>
>
>   lon2d = f1*[0]*->lon             ; read NARR longitude from 1st file
>   lat2d = f1*[0]*->lat             ; read NARR latitude
>
> -----------------
>
>
> See attached. It is a combination of your script and ESMF_wgts_30.ncl
>
>
>
> On Sat, Feb 29, 2020 at 2:56 PM dale zuri via ncl-talk <ncl-talk at ucar.edu>
> wrote:
>
>> Hi NCL user,
>> I have been trying to regrid NARR 0.3 resolution to 190x384 using the
>> ESMF regrid function. The regrid was successful, however the output values
>> seem unrealistic and not correct.
>> I would appreciate any suggestion to fix the problem.
>> Thanks
>>
>> Here the code:
>>  diri1 = "/NARR/daily/prate/"
>>
>> fill1 = systemfunc("for((i="+yrstrt+";i<="+yrend+";i+=1)); do ls "+
>> diri1 +"*$i*; done")
>>
>> print(fill1)
>>
>> f1    = addfiles (fill1, "r")   ; note the "s" of addfile
>>
>> ListSetType (f1, "cat")
>>
>> uT1    = f1[:]->prate             ; read T from all files
>>
>> lon2d    = f1[:]->x             ; read T from all files
>>
>> lat2d    = f1[:]->y             ; read T from all files
>>
>> printVarSummary (uT1)
>>
>>   uT1 at _FillValue = uT1 at missing_value  ; fix missing value
>>
>> printMinMax(uT1,0)
>>
>>   uT  = short2flt( uT1 )   ; apply scale and offset attributes
>>
>> xMon = calculate_monthly_values (uT, "avg", 0,True)
>>
>> printVarSummary(xMon)
>>
>> printMinMax(xMon,0)
>>
>> T1 = month_to_season (xMon, "JJA")
>>
>> printVarSummary(T1)
>>
>> T1=T1*86400*92
>>
>> printMinMax(T1,0)
>>
>> ;-- define the T255 grid (lat x lon - 256x512)
>>
>> nlat = 190 ;-- number of latitudes
>>
>> nlon = 384 ;-- number of longitudes
>>
>> grint = 0.9375 ;-- grid spacing
>>
>> dst_lat = fspan((-90.0+grint),(90.-grint),nlat)*1d ;-- type double
>>
>> dst_lat!0 = "lat" ;-- dimension name
>>
>> dst_lat at units = "degrees_north" ;-- dimension units
>>
>> dst_lon = fspan(0.0,(360.-grint),nlon)*1d ;-- type double
>>
>> dst_lon!0 = "lon" ;-- dimension name
>>
>> dst_lon at units = "degrees_east" ;-- dimension units
>>
>> ;-- set ESMF resources
>>
>> Opt = True
>>
>> Opt at InterpMethod = "patch" ;-- interpolation method
>>
>> Opt at SrcFileName = "ECHAM5_SCRIP_bilinear.nc" ;-- new source file name
>>
>> Opt at WgtFileName = "ECHAM5toWorldCurvilinear_bilinear.nc";-- weights file
>>
>> Opt at ForceOverwrite = True ;-- force overwrite
>>
>>  Opt at DstFileName = "WorldRectilinear_SCRIP_bilinear.nc";-- destination
>> file
>>
>> Opt at DstGridType = "rectilinear" ;-- Destination grid
>>
>> Opt at DstGridLon = dst_lon
>>
>> Opt at DstGridLat = dst_lat
>>
>> newgrid = ESMF_regrid(T1,Opt)
>>
>> ;newgrid  = f2fsh_Wrap(T1,(/190,384/))
>>
>> printVarSummary (newgrid)
>>
>> printMinMax(newgrid,0)
>>
>>
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>
>
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