[ncl-talk] linint2_point

[Ehsan Taghizadeh]

 Dears Ian and Kwesi,I really appreciate for your helpful comments. I learnt much from them. However, about Kwesi's comment, may I ask why someone wanna interpolate higher resolution to the lower resolution, as you said "That is why more commonly higher resolution grids would be interpolated to lower resolution".

May I ask more help?My work included different grid data with different spatial resolution; 0.1, 0.5 and 0.75 degree. I think I should reply to the referee related to these spatial resolution differences which included in my work, maybe the influence of these differences in the interpolation.The referee asked: "Please discuss also thespatial scale resolution differences in products and interpolationimplications."

Sincerely,Ehsan
    On Saturday, July 18, 2020, 12:00:41 PM GMT+4:30, Kwesi A. Quagraine <starskykwesi at gmail.com> wrote:  
 
 #yiv8752248087 body{font-family:Calibri, Arial;font-size:13px;}Dear Ehsan,
Follow from Ian’s explanation; as an example, lower resolution grids have less spatial variance than higher resolution grids and interpolating the lower resolution to a higher resolution does not change this. Thus taking a lower resolution grid to a higher resolution grid does not add information. The interpolated data will have low spatial and temporal variance.That is why more commonly higher resolution grids would be interpolated to lower resolution. 
This information has to be explicitly stated in your paper; because there are some analysis that are sensitive to interpolation and readers have to bear that in mind when comparing results.
Hope this helps.
RegardsKwesi
On 17 July 2020 at 18:48:39, Ian Harris (ENV - Staff) via ncl-talk (ncl-talk at mailman.ucar.edu) wrote:
 

Hi,
I'd say they want you to examine the resolution of your input andoutput data, in case the interpolation could be judged, er,'optimistic'. For instance, if I had data on a 5° grid, I couldeasily interpolate it onto a 0.5° grid, but there are implicationsbecause you're not inventing new data, you're still stuck with the5° data but on a finer grid.
Cheers
Harry
From: ncl-talk<ncl-talk-bounces at mailman.ucar.edu> on behalf of EhsanTaghizadeh via ncl-talk <ncl-talk at mailman.ucar.edu>
Sent: 17 July 2020 17:12
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Subject: [ncl-talk] linint2_point 
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Dear NCL group,
I hope you're doing great.I have a general question and I hope I could haveyour help, as usual.In one paper I wrote "The interpolation was done using the bilinearmethod in NCL (NCAR Command Language)". Actually, Iinterpolated some grid precipitation products on gauged stationsusing "linint2_points" from NCL.The referee commented "Withhow many points? Please discuss also the spatial scale resolutiondifferences in products and interpolationimplications."I wanna reply "Asmentioned in the paper, we used NCL in the most programming. NCLhas a function named linint2_points which interpolates from arectilinear grid to an unstructured grid using bilinearinterpolation based on the four closest grid points to a particular(x, y) coordinate pair." However, I don't know howreply to the part of discussing about different spatial resolution.May I ask some help about that, please?
Sincerely,Ehsan TaghizadehPhD student ofMeteorology,Institute of Geophysics,University of Tehran, Iran_______________________________________________
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Kwesi A. QuagraineDepartment of PhysicsSchool of Physical SciencesCollege of Agriculture and Natural SciencesUniversity of Cape CoastCape Coast, Ghana
Alt. Email: kwesi at csag.uct.ac.za Web: http://www.recycleupghana.org/ 
Office: +27 21 650 1563Skype: quagraine_cwasi  
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