[ncl-talk] Question on interpolation

[Andrew Kren - NOAA Affiliate]

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)
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