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The analysis data are typically provided at regular lat/lon grids. The following fields are mandatory: physical fields of PS, PHSI, T, Q, U, V, and vertical coordinate related variables, namely, P0,  hyam, hybm, hyai, hybi for hybrid simga-pressure coordinate and  lev and ilev for constant pressure levels.

The IFS data provided by the DYAMOND initial is at full 640 gaussian grids, ifs_oper_T1279_2016080100.nc. It contains the required fields but need to be either renamed (t,q,u,v,z_2_ or converted (e.g., lhsp). It has the hybrid coordinate coefficient variables but using different vertical coordinate dimension names than the ones used to define the physical fields.  NCO vertical interpolation function may have been updated to recognize such hybrid coefficient variables. The workflow as used here opt to re-define these variables using consistent vertical dimension names.

The above can be done using  /project/projectdirs/m2136/analysis-IC/ifs_modify.sh.

The modified file is named is ifsas ifs_oper_T1279_2016080100_mod.nc. Not all  variables in the file are needed for IC. A subset of it, ifs_oper_T1279_2016080100_mod_subset.nc, is used for the remaining steps.