extrapolation

General scientific issues regarding ROMS

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redhat007

extrapolation

#1 Post by redhat007 » Sun Mar 01, 2015 12:33 pm

dear friend
i know that ROMS just do interpolation not extrapolation. So, i am looking froward some functions (especially in Matlab) for extrapolating input fields.
Can you help me
cheers
redhat

lithodes8

Re: extrapolation

#2 Post by lithodes8 » Tue Mar 03, 2015 11:26 am

Hi, I understand that extrapolation is like interpolation only in the end put a zero and matlab extrapolated.

Vq = interp3(___,method,extrapval*) also specifies extrapval, a scalar value that is assigned to all queries that lie outside the domain of the sample points.

If you omit the extrapval argument for queries outside the domain of the sample points, then based on the method argument interp3 returns one of the following:
The extrapolated values for the 'spline' method
NaN values for interpolation methods other than 'spline'

* This valor is cero (0).
works for me...
regards

rtopper
Posts: 24
Joined: Fri Jul 04, 2014 2:32 pm
Location: MARUM, University of Bremen

Re: extrapolation

#3 Post by rtopper » Tue Mar 03, 2015 11:36 am

You can also use this function:
http://de.mathworks.com/help/matlab/ref ... class.html

With examples of how to use it for extrapolation here:
http://de.mathworks.com/help/matlab/mat ... ation.html

turuncu
Posts: 128
Joined: Tue Feb 01, 2005 8:21 pm
Location: Istanbul Technical University (ITU)
Contact:

Re: extrapolation

#4 Post by turuncu » Wed Mar 04, 2015 6:28 am

Hi,

You can use NCL to extrapolate data. Look at the following page,

https://www.ncl.ucar.edu/Applications/grid_fill.shtml

You could also use ESMF regridding capability in NCL. In this case, you could perform two step interpolation. Look at the attached example. It interpolates low resolution atmosphere model output to high resolution ocean model grid. I hope it helps.

--ufuk
Attachments
esmf_extrapolation_ex.ncl
NCL script for two level interpolation (bilinear+nn)
(4.6 KiB) Downloaded 60 times

d.kobashi
Posts: 55
Joined: Tue Sep 28, 2010 11:59 pm
Location: Texas A&M University

Re: extrapolation

#5 Post by d.kobashi » Wed Mar 04, 2015 11:43 am

I used to use the following function. Worked fine.
http://www.mathworks.com/matlabcentral/ ... paint-nans
Use with caution.

DJ@TAMU

redhat007

Re: extrapolation

#6 Post by redhat007 » Thu Mar 05, 2015 8:15 am

Dear friends
i would like to offer my heartfelt appreciate for your kindly replies
cheers
redhat

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