NESTDOWN Tutorial : Introduction
The function of program NESTDOWN is two-fold.
- First, it is used to generate input files for a one-way nested
MM5 run.
- In this scenario, MM5 model is first run
on some coarser mesh(es).
- NESTDOWN takes output from MM5, together
with TERRAIN output for a finer mesh, and
generates input files for another MM5 run on the finer mesh.
- For example, you can run MM5 at 90 and 30 km resolutions
first, then take the model output at 30 km resolution and
10 km TERRAIN output (or any integer coarse-to-fine mesh
ratio) in NESTDOWN, and NESTDOWN will generate input files
for MM5 at 10 km. (graphical depiction)
- Second, NESTDOWN can be used to generate nest input files
for MM5.
- You may notice that Version 3's INTERPF program only produces
input files for MM5 at one resolution.
- This is because MM5 can start nests with the option of
inputting a nest terrain file (IOVERW=2 option).
- But if you would like to generate nest input files, use
NESTDOWN.
- This program works with sigma-level data, and requires
nest terrain to be in the input files (you cannot do horizontal
interpolation without inputting the finer mesh terrain).
(graphical depiction)
As an example, we will be running NESTDOWN to generate input
for a second high resolution MM5 run (first function above).
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