# Re: Fwd: interpolation gridded data to rcm

From: Dennis Shea <shea_at_nyahnyahspammersnyahnyah>
Date: Mon Feb 07 2011 - 17:01:47 MST

I am not clear what you mean by
"interpolate 2d randomly-spaced data to
another 2d randomly-spaced data or 2d randomly
spaced data to directly RCMs grid"

```---
There is a function in NCL' contributed.ncl that may work.
Like "natgrid" this can be slow!!!!
function obj_anal_ic_deprecated(X[*],Y[*],Z[*],lon:numeric,lat:numeric \
,dcrit[*]:numeric, opt:logical)
===
opt = 0
zrcm = obj_anal_ic_deprecated(loni,lati,zi, dcrit, lon2d,lat2d, opt)
input: loni[*], lati[*], zi[*]
output: lon2d[*][*], lat2d[*][*]
; dcrit        - 1D array containing successive radii of influence.
;                Must be expressed in degrees latitude and should be
;                monotonically de.  eg: dcrit = (/5, 3/)
On 2/7/11 9:59 AM, Debasish wrote:
> Hello,
>
> Thanks Dennis for your suggestion. However I believe the function "triple2grid2d" places randomly-spaced data onto the nearest locations of a grid instead of interpolation while I need to do a interpolation. I also checked http://www.ncl.ucar.edu/Document/Functions/regrid.shtml but did not find any function that can interpolate randomly-spaced data to another randomly-spaced data or RCMs grid.
>
> Therefore, I would like to know is there any function or any way in NCL to interpolate 2d randomly-spaced data to another 2d randomly-spaced data or 2d randomly spaced data to directly RCMs grid.
>
> Any help in this regard will be appreciated and sorry for any inconvenience
>
> Thanks
>
> Debasish
>
>
>
>
> On 2011-02-03, at 14:36, Dennis Shea wrote:
>
>> You would have to convert to ascii, the use asciiread.
>>
>> "natvar" is high quality but is known to be slow.
>>
>> Really, if you have a large number of high res\
>> grids you need interpolated to an RCM grid,
>> there is not magic bullet. it will take time.
>>
>> The following *may* be useful.
>>
>>
>> http://www.ncl.ucar.edu/Document/Functions/Built-in/triple2grid2d.shtml
>>
>> Good luck
>>
>> On 2/3/11 12:02 PM, Debasish wrote:
>>> Dear NCL Users
>>>
>>> I guess I am getting missing outputs because of the assumption that xin
>>> is gridded RCM data because neither lon proceeds left to right nor lat
>>> proceeds from south-to-north.
>>>
>>> I have tried to use "natgrid" assuming xi (mxn) with lat(mxn) and
>>> lon(mxn) but the program is hang. I guess it does not work too.
>>>
>>> Therefore, I would like to know how do I interpolate this data (high
>>> resolution data) to RCM grid with lat2d(172,180), lon2d(172,180).
>>> Meanwhile I counted that there are nearly 450 RCM grid over the input
>>> domain; so I would like to interpolate the input data to this 450 CRCM
>>> grid.
>>> I am sending the part (total file has 17536 lat, lon and xin) of lat and
>>> lon of the input data for your convenience .
>>>
>>> Any help in this regard will be appreciated
>>>
>>> Thanks
>>>
>>> Debasish
>>>
>>> =
>>>
>>>
>>>
>>> Begin forwarded message:
>>>
>>>> *From: *Debasish<debasish@sca.uqam.ca<mailto:debasish@sca.uqam.ca>>
>>>> *Date: *1 février 2011 16:42:48 HNE
>>>> *To: *Ncl Talk<ncl-talk@ucar.edu<mailto:ncl-talk@ucar.edu>>
>>>> *Subject: **[ncl-talk] interpolation gridded data to rcm*
>>>>
>>>> Dear NCL users,
>>>>
>>>> I have gridded data xin (m,n) with lat(m,n) and lon(m,n) for smaller
>>>> domain. I would like to interpolate the data to RCM grid lat2d(a,b)
>>>> and lon2d(a,b) for bigger domian.
>>>> I follow the followings steps:
>>>>
>>>> 1. I assume "xin" as RCM gridded data
>>>> 2. convert lat2d and lon2d to 1d array lat1d and lon1d
>>>> 3. Use "rcm2points" function
>>>> xout1d = rcm2points(lat,lon,xin,lat1d,lon1d,0)
>>>> 4. then convert xout1d to 2d
>>>> but all the values of xout1d are missing
>>>>
>>>> Any suggestion to fix these problem will be appreciated
>>>>
>>>> Thanks
>>>>
>>>> Debasish
>>>> _______________________________________________
>>>> ncl-talk mailing list
>>>> List instructions, subscriber options, unsubscribe:
>>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>
>>> =
>>>
>>>
>>>
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```
Received on Mon Feb 7 17:01:52 2011

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