[Thread Prev][Thread Next][Index]
Re: [ferret_users] interpolation
Hi David,
Yes, linear interpolation uses the grid points themselves and does
linear interpolation between them. The @AVE regridding transformation
uses the "boxes" or portions of boxes. The dataset CAN specify where
cell edges are, if it uses the NetCDF bounds attribute.
Ansley
David Wang wrote:
Thanks a lot, Ansley.
Now I'm aware that it is Ferret, not the dataset itself, that sets
cell edges at midpoints between grid points. So if I understand it
correctly, linear interpolation through regridding has nothing to do
with the position of cell edges, it simply takes two adjacent grid
points and calculates the linear combination at the target point in
between, doesn't it?
- D.W.
Ansley Manke wrote:
Hi David,
By default Ferret assumes that cell edges are midway between grid
points, in the absence of other information. Using the concept of
cell boundaries/edges one can define the axis in whichever way you
like, however in this case it seems that Ferret's definition of the
cells on the axis is the one you already want:
yes? use levitus_climatology
yes? let zz = z[gz=temp]
yes? let zlo = zboxlo[gz=temp]
yes? let zhi = zboxhi[gz=temp]
yes? list zz, zlo, zhi, zz-zlo, zhi-zz
DATA SET:
/home/porter/tmap/fer_dsets/data/levitus_climatology.cdf
DEPTH (m): 0 to 5000
Column 1: ZZ is Z[GZ=TEMP]
Column 2: ZLO is ZBOXLO[GZ=TEMP]
Column 3: ZHI is ZBOXHI[GZ=TEMP]
Column 4: EX#4 is ZZ-ZLO
Column 5: EX#5 is ZHI-ZZ
ZZ ZLO ZHI EX#4 EX#5
0 / 1: 0. 0. 5. 0.0 5.0
10 / 2: 10. 5. 15. 5.0 5.0
20 / 3: 20. 15. 25. 5.0 5.0
30 / 4: 30. 25. 40. 5.0 10.0
50 / 5: 50. 40. 62. 10.0 12.5
75 / 6: 75. 62. 88. 12.5 12.5
100 / 7: 100. 88. 125. 12.5 25.0
150 / 8: 150. 125. 175. 25.0 25.0
200 / 9: 200. 175. 250. 25.0 50.0
300 / 10: 300. 250. 350. 50.0 50.0
400 / 11: 400. 350. 500. 50.0 100.0
600 / 12: 600. 500. 700. 100.0 100.0
800 / 13: 800. 700. 900. 100.0 100.0
1000 / 14: 1000. 900. 1100. 100.0 100.0
1200 / 15: 1200. 1100. 1350. 100.0 150.0
1500 / 16: 1500. 1350. 1750. 150.0 250.0
2000 / 17: 2000. 1750. 2500. 250.0 500.0
3000 / 18: 3000. 2500. 3500. 500.0 500.0
4000 / 19: 4000. 3500. 4500. 500.0 500.0
5000 / 20: 5000. 4500. 5000. 500.0 0.0
[Thread Prev][Thread Next][Index]
Dept of Commerce /
NOAA /
OAR /
PMEL /
TMAP
Contact Us | Privacy Policy | Disclaimer | Accessibility Statement