[ecco-support] ECCOv4r4 Arctic Cap to WGS-84 geocentric coordinate system conversion

[Samar Khatiwala]

Hi Ashfaq,

There may be some functions for interpolation in the ECCO matlab/python
packages. Personally, I've found the most robust way is griddatan in Matlab
or scipy.griddata in python. If you have to do the interpolation multiple
times over (e.g., for different time slices) then I would recommend
scatteredInterpolant in Matlab. (I don't know if there's an equivalent in
python but in any case I trust Matlab more.) This precomputes interpolation
weights for a given set of scattered data points (e.g., the ECCO Arctic cap
). While the intent of this function is to let you repeatedly interpolate
the *same* field to different target points (without having to recalculate
the weights), there's an undocumented feature that also enables you to
efficiently interpolate *different* fields. The scatteredInterpolant object
exposes a struct with one of the fields being an array called 'Values'. To
interpolate a different field all you have to do is replace the data in
Values with the new data. Matlab won't know any better and will happily do
the interpolation. I've used this approach for OSI-SAF ice velocity data.

Hope that helps.

Samar

On Thu, Jun 27, 2024 at 2:31 PM Ahmed, Ashfaq <ashfaq_ahmed at brown.edu>
wrote:

> Good morning team,
>
> I am a PhD student at Brown University, and I study the dynamics of the
> near-surface circulation in the Arctic Ocean. As part of one of the
> projects, I am trying to make an intercomparison between the ECCO sea ice
> products (e.g., sea ice velocity, thickness, drift speed, curl, angle) with
> other reanalysis products (e.g., NSIDC, OSI-SAF).
>
> To make this comparison, I need to convert the Arctic cap into a WGS-84
> geocentric coordinate system. Because the coordinate reference system (CRS)
> for the rest of the products is WGS-84, and I want the ECCO to be the same
> for a perfect comparison.
>
> I did not find any document that might allow me to make this conversion.
> Could you kindly help me with this? I would really appreciate any feedback
> from you!
>
> [image: Many thank to Brown University for sponsoring our 50th Anniversary
> celebration]
> Thanks,
> *Ashfaq Ahmed* (he/his)
> Doctoral Student,
> Center for Fluids and Thermal Science
> <https://engineering.brown.edu/people/graduate-students/phd-students/phd-students-fluids-and-thermal-sciences>
> School of Engineering, Brown University
> Lab website: wilhelmuslab.me
> Email: ashfaq_ahmed at brown.edu <ramisa_fariha at brown.edu>
> *Profile Links -*
> *LinkedIn <https://www.linkedin.com/in/ashfaqahmed40/> | Website
> <https://ashfaqnihalbuet.wixsite.com/website> | Google Scholar
> <https://scholar.google.com/citations?user=iiSUYgsAAAAJ&hl=en&authuser=1> | ResearchGate
> <https://www.researchgate.net/profile/Ashfaq-Ahmed-15>*
> Providence, Rhode Island, USA
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