Re: interpolation error of station into gridded data

Hi Jin-Young,
I think the main reason why you are getting unreasonable values is
because you are attempting to interpolate data that is bounded by 0..
Your data is also highly fractal, thus there are large variations across
small distances. Interpolation with splines is not recommended when
dealing with this type of data.

There is a new interpolation function that will be in the next release
of NCL that is recommended when dealing with this type of interpolation
that I will send you in a separate email.
Adam

Mary Haley wrote:
> Jin-Young,
>
> The idsfft function is not one of our better interpolation routines,
> as our documentation states.
>
> You might try some other functions, like natgrid:
>
> http://www.ncl.ucar.edu/Document/Functions/Built-in/natgrid.shtml
>
> or triple2grid, which doesn't do interpolation:
>
> http://www.ncl.ucar.edu/Document/Functions/Built-in/triple2grid.shtml
>
>
> The documentation for these routines point to some other routines
> that might be of use.
>
> --Mary
>
> On Wed, 31 Dec 2008, Jin-Young Kim wrote:
>
>> I've tried after exchanging x-coordinate and ycoordinate.
>> But results is same..
>>
>> Do you know other problem?
>>
>> Best regards,
>> Jin-Young Kim
>>
>> On Wed, Dec 31, 2008 at 11:19 AM, Adam Phillips
>> <asphilli_at_cgd.ucar.edu>wrote:
>>
>>> Hi Jin-Young,
>>> I think you have the lat/lon inputs switched. According to the
>>> documentation the first input should contain the x-coordinates
>>> (longitude),
>>> and the second input should contain the y-coordinates (latitude).
>>> Adam
>>>
>>> Jin-Young Kim wrote:
>>>
>>>> I'm trying to interpolate random data into gridded data.
>>>> But it's so big differences between input and output value.
>>>>
>>>> --> before interpolation
>>>> (0) min_val of in_rain= 0
>>>> (0) max_val of in_rain= 80.33
>>>> --> after interpolation
>>>> (0) min_val of out_rain= -931.531
>>>> (0) max_val of out_rain= 1026.31
>>>>
>>>> Here is ncl scripts and output log
>>>>
>>>> Does anybody know the reason?
>>>>
>>>> Best regards,
>>>> Jin-Young Kim
>>>>
>>>> --
>>>> Ph. D. Student
>>>> Jin-Young Kim (jin_at_climate.pknu.ac.kr <mailto:jin_at_climate.pknu.ac.kr>)
>>>> Integrated Climate System Modeling Lab.
>>>> Department of Environmental Atmospheric Sciences
>>>> Pukyong National University, Busan 608-737, South Korea
>>>> Web : http:climate.pknu.ac.kr/~jin <http://climate.pknu.ac.kr/%7Ejin> <
>>>> http://climate.pknu.ac.kr/~jin <http://climate.pknu.ac.kr/%7Ejin>>
>>>>
>>>> Visiting Scholar
>>>> Jin-Young Kim (Jin-Young.Kim_at_noaa.gov <mailto:Jin-Young.Kim_at_noaa.gov>)
>>>> Global Systems Division
>>>> Earth System Research Laboratory
>>>> R/GSD7
>>>> 325 Broadway
>>>> Boulder, CO80305-3328
>>>>
>>>> +1-303- 497-4422 (Office)
>>>> +1-303- 497-7262 (FAX)
>>>>
>>>>
>>>> ------------------------------------------------------------------------
>>>>
>>>>
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>>>> ncl-talk mailing list
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>>>
>>> --
>>> --------------------------------------------------------------
>>> Adam Phillips asphilli_at_ucar.edu
>>> National Center for Atmospheric Research tel: (303) 497-1726
>>> ESSL/CGD/CAS fax: (303) 497-1333
>>> P.O. Box 3000
>>> Boulder, CO 80307-3000 http://www.cgd.ucar.edu/cas/asphilli
>>>
>>
>>
>>
>> --
>> Ph. D. Student
>> Jin-Young Kim (jin_at_climate.pknu.ac.kr)
>> Integrated Climate System Modeling Lab.
>> Department of Environmental Atmospheric Sciences
>> Pukyong National University, Busan 608-737, South Korea
>> Web : http:climate.pknu.ac.kr/~jin
>>
>> Visiting Scholar
>> Jin-Young Kim (Jin-Young.Kim_at_noaa.gov)
>> Global Systems Division
>> Earth System Research Laboratory
>> R/GSD7
>> 325 Broadway
>> Boulder, CO80305-3328
>>
>> +1-303- 497-4422 (Office)
>> +1-303- 497-7262 (FAX)
>>
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-- 
--------------------------------------------------------------
Adam Phillips			             asphilli_at_ucar.edu
National Center for Atmospheric Research   tel: (303) 497-1726
ESSL/CGD/CAS                               fax: (303) 497-1333
P.O. Box 3000				
Boulder, CO 80307-3000	  http://www.cgd.ucar.edu/cas/asphilli
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