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GEOS-ESM / MAPL

MAPL is a foundation layer of the GEOS architecture, whose original purpose is to supplement the Earth System Modeling Framework (ESMF)
https://geos-esm.github.io/MAPL/
Apache License 2.0
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Can the vertical interpolation performance be improved? #2202

Open weiyuan-jiang opened 1 year ago

weiyuan-jiang commented 1 year ago

In current vertical interpolation, for each level, it goes through all the levels to find out corresponding horizontal points, and then calculates the weight and does the linear interpolation. So it is roughly K*K algorithm

https://github.com/GEOS-ESM/MAPL/blob/29c9ba32a3144509d35025f6b99f20efb53de4ab/base/MAPL_VerticalMethods.F90#L604-L616

Can we improve the algorithm by saving the indices and weights ? So the interpolation would look like

OutVars(i(:), j(:), ik(:)) = inVars(i(:),j(:),ik(:))*weight((i:),j(:), ik(:) + inVars(i(:),j(:),ik(:)+1)*(1- weight((i:),j(:), ik(:))

Here i(:), j(:), ik(:) and weight are calculated and saved every time the pressure ( or vcoord) are updated

@bena-nasa @atrayano @tclune

tclune commented 1 year ago

I don't think that is quite the structure. Instead I think you have k(:,:), and weight(:,:).

And we want to encapsulate this. something like:

type VInterpolator
   integer, allocatable :: k_ij(:,:)
   real, allocatable :: w_ij(:,:)
contains
  procedure :: interpolate
end
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