icon-eu download data

[Ming Chen]

Hi, Julianrvogel,

All upper air variables included in the intermediate files should be on the same levels. Otherwise metgrid cannot run successfully. I believe this is the reason why your case failed. In your yesterday's post (December 4), I found two variables both named "GHT" but their values are different as shown below:

================================================
FIELD = GHT
UNITS = m DESCRIPTION = Height
DATE = 2023-08-11_21:00:00 FCST = 0.000000
SOURCE = DWD
LEVEL = 66.000000
I,J DIMS = 1214, 745
IPROJ = 0 PROJECTION = LAT LON
REF_X, REF_Y = 1.000000, 1.000000
REF_LAT, REF_LON = 43.180000, 356.059998
DLAT, DLON = 0.020000, 0.020000
EARTH_RADIUS = 6371.229492
DATA(1,1)=189.067993

================================================
FIELD = GHT
UNITS = m DESCRIPTION = Height
DATE = 2023-08-11_21:00:00 FCST = 0.000000
SOURCE = DWD
LEVEL = 65.000000
I,J DIMS = 1214, 745
IPROJ = 0 PROJECTION = LAT LON
REF_X, REF_Y = 1.000000, 1.000000
REF_LAT, REF_LON = 43.180000, 356.059998
DLAT, DLON = 0.020000, 0.020000
EARTH_RADIUS = 6371.229492
DATA(1,1)=209.088318
================================================

I guess both are GHT but the first one (66-level) are GHT on full model levels, while the second one (65-level) should be GHT on half levels. If this is indeed the case, then you can simply remove the first full-level GHT and use the one on half-levels.

Please let me know whether this works for you.

 

[julianrvogel]

Dear Ming,

Thank you for clarifying that all upper air variables must be on the same levels. Then the only way is to destagger the level heights beforehand.

The level heights (GHT) of ICON forcing are given only on full model levels (as is W), while most other variables (P, T, U, V, Q) are given on half model levels. Level 66 is actually the ground surface, 65 is the first level above ground and level 1 is top of atmosphere.

Note: I am using ICON-D2, which has 65 half and 66 full levels. The original download script was for ICON-EU, which has 74 half and 75 full levels.

The reason why the ICON forcing has worked so far, is that the download script omits the last level 66 for ICON-D2 (or level 75 for ICON-EU). When removing the last level, metgrid works, but it actually assigns the staggered level heights to the non-staggered variables.

What I did now is to destagger the 66 full levels to the 65 half levels, using eccodes in Python directly on the grib files, before ingesting them to ungrib. Now metgrid works and the level heights should be correct. I believe this is a step everyone needs to do when using ICON forcing.