M3cple behaviour in regriding

I/O API
1

Hi
As per the recommendation of @cjcoats in here, I tried m3cple from the m3tools to regrid data from a large domain with coarse grid (36 km) to a smaller one with fine cells (1.8 km). The projection systems of both grids are Lambert and the smaller domain is somehow in the center of the larger one. However, the visualization of the re-grided data shows something unusual. I attach the PM10 plots from both files with a similar shapefile underneath to show the relative positions of the grids. It seems that the interpolation in y-direction is ok, but in x-direction the regrided data doesn’t match with the original one. The data in the re-grided file is like vertical strips, while I expected to see square zones of the same value distributed on about 20x20 cells of the smaller grid.
Can it be a bug? I appreciate if anyone can shed some light on this issue.

cheers

original
original762×673 5.03 KB

regrided
regrided757×673 5.89 KB

2

No one from the IO-API side to comment on this?!

3

I am a bit confused about using m3cpl to regrid from a course resolution to a finer resolution.

Quote from Carlie’s documentation:

" For interpolation to be meaningful, the output resolution should be finer than the input resolution, else you should not be using any interpolation, but rather should be using some sort of aggregation algorithm (possibly using a matrix from program MTXBUILD in conjunction with program MTXCPLE)."

4

Can you provide a sample 1 hour course resolution combine file, and the GRIDDESC files you are using for the course grid and fine grid, so that we can reproduce the issue you are reporting?