[ncl-talk] Question on interpolation

[Andrew Kren - NOAA Affiliate]

Thanks Dennis! That worked perfectly! You may close this ticket.

Thanks,

On Tue, Sep 3, 2019 at 6:21 PM Dennis Shea <shea at ucar.edu> wrote:

> Sorry if what I wrote was not clear.
>
> A sketch of a script follows.
> ===========================
>   dirHWRF  = "..."
>   filHWRF   = "..."
>   pthHWRF = dirHWRF + filHWRF
>   nfil    = *dimsizes*(filHWRF)
>
> ; Trick to have NCL do book-keeping of 'time'.
> ; Have NCL's addfiles create a 'time' array that spans all times
> ; It is assumed that there is one time step per file
> ;;setfileoption("grb","SingleElementDimensions",(/"Initial_time",
> "Forecast_time"/))
>   *setfileoption*
> <https://www.ncl.ucar.edu/Document/Functions/Built-in/setfileoption.shtml>("grb","SingleElementDimensions",
>  "Initial_time")
>
>   fadd    = *addfiles*
> <https://www.ncl.ucar.edu/Document/Functions/Built-in/addfiles.shtml>
> (pthHWRF,"r")
>   time    = fadd*[:]*->initial_time0_hours   ; times acriss all files
>   time!0  = "time"
>   ntim    = *dimsizes*(time)
>   ymdh    = c*d_calendar*(time,-3)
>   ymdh!0  = "time"
>   print(time+"  "+ymdh)
>   print("------------")
>
>   if (ntim.ne.nfil) then
>       print("nim="+ntim+" : nfil="+nfil: should be equal)
>       exit
>   end if
>
>   plev    = *ff[0]*->lv_ISBL0   ; get from 1st file [invariant]
>   plev!0  = "plev"
>   print(plev)
>   delete(fadd)
>
> ;---Sonde locations
>
>   SLAT = (/lat1, lat2, lat3/)   ; one or more Sonde lat
>   SLON = (/lon1, lon2, lon3/)
>   npts = dimsizes(SLAT)
>
>   xsonde = new((/ntim,klev,npts/),"float", -1e10)   ; allocate space for
> variable
> ;;ysonde = new((/ntim,klev,npts/),"float", -1e10)
> ;;zsonde = new((/ntim,klev,npts/),"float", -1e10)
>
>   do nf=0,nfil-1    one time step per file; lat_0, lon_0 coordinates may
> change
>        f = *addfile*(pthHWRF*(nf)*,"r")
>        x = f->X        ; X( initial_time0_hours0, lv_ISBL0, lat_0, lon_0 )
>        xsonde(nf,:,:)) =  *linint2_points_Wrap*
> <https://www.ncl.ucar.edu/Document/Functions/Contributed/linint2_points_Wrap.shtml>(x&lon_0,
> x&lat_0, x, False,SLAT,SLON 0)
>   end do
>
>   xsonde!0       = "time"
>   xsonde&time =  time
>   xsonde!1       = "plev"
>   xsonde&plev =  plev
>   xsonde!2       = "sonde"
>
>   *printVarSummary*(xsonde)
>
>
> On Tue, Sep 3, 2019 at 3:51 PM Andrew Kren - NOAA Affiliate <
> andrew.kren at noaa.gov> wrote:
>
>> So what you are saying is that I should interpolate to the location
>> first. Then after I do that, I can interpolate multiple locations to the
>> time? This is how I understand it given the limitation.
>>
>> Thanks,
>>
>> On Tue, Sep 3, 2019 at 2:59 PM Dennis Shea <shea at ucar.edu> wrote:
>>
>>> I assume you are processing multiple GRIB2 files using *addfiles.*
>>> This is appropriate if the same grid is applicable to all files.
>>> *addfiles *will concatenate all the file times. You only need to use
>>> one grid.
>>> ---
>>> In the case of the HWRF grids (possibly) changing at each time step, you
>>> will have to step through the files manually. This means you will have to
>>> do some book-keeping.
>>>
>>>   dirHWRF = "..."
>>>   filHWRF  = "..."
>>>   pthHWRF = dirHWRF + filHWRF
>>>   nfil = dimsizes(filHWRF)
>>>
>>>   SLAT =    ; one or more Sonde lat
>>>   SLON =
>>>
>>>   do nf=0,nfil-1
>>>        f = addfile(pthHWRF(nf),"r")
>>>        x = f->X
>>>        xsonde(nf.....) =  *linint2_points*(x&lon_0, x&lat_0,
>>> False,SLAT,SLON 0)
>>>
>>>      end do
>>>
>>> Good Luck
>>>
>>> On Tue, Sep 3, 2019 at 1:19 PM Andrew Kren - NOAA Affiliate via ncl-talk
>>> <ncl-talk at ucar.edu> wrote:
>>>
>>>> Dear ncl-talk,
>>>>
>>>> I am working to interpolate a high-resolution model dataset (HWRF) to
>>>> the time and location of a dropsonde location. In the past for other
>>>> datasets, I have used linint1_n and linint2_points to interpolate in time
>>>> and space to the dropsonde position.
>>>>
>>>> However, HWRF, which is 6-hour analysis output, has a varying grid
>>>> every 6 hours as the domain "moves" with the tropical cyclone. Hence, the
>>>> lat/lon locations are not fixed in time. They have the same dimension sizes
>>>> but the points vary depending on the cyclone center. This led to an error
>>>> in my linint2_points function:
>>>>
>>>> fatal:linint2_points: If xi is not one-dimensional, then it must have
>>>> one less dimension than fi
>>>>
>>>>
>>>>
>>>> I know why this is happening. I read in two HWRF files around the
>>>> dropsonde time to do the interpolation. I used "join" to join the files and
>>>> my lat/lon arrays are (time, lat) and (time, lon). So I get the error.
>>>>
>>>>
>>>> But my question is how best to proceed? This is technically not an
>>>> unstructured grid, but could be considered one. Should I use ESMF?
>>>>
>>>>
>>>> Thanks,
>>>>
>>>> --
>>>> Andrew Kren
>>>> Assistant Scientist
>>>> University of Miami CIMAS - NOAA/AOML
>>>> Global Observing Systems Analysis (GOSA) Group
>>>> NOAA/AOML Quantitative Observing System Assessment Program (QOSAP)
>>>> _______________________________________________
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>>>
>>>
>>
>> --
>> Andrew Kren
>> Assistant Scientist
>> University of Miami CIMAS - NOAA/AOML
>> Global Observing Systems Analysis (GOSA) Group
>> NOAA/AOML Quantitative Observing System Assessment Program (QOSAP)
>>
>

-- 
Andrew Kren
Assistant Scientist
University of Miami CIMAS - NOAA/AOML
Global Observing Systems Analysis (GOSA) Group
NOAA/AOML Quantitative Observing System Assessment Program (QOSAP)
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