generate an initial data from NCEP or ECMWF reanalysis data

[snowyang1988@gmail_com]

Hi, could someone help me? I am using F-SD-WACCM for seasonal or weekly forecasts experiments. I want to generate an initial data from NCEP or ECMWF reanalysis data to run the model. But I don’t know how to do it. The CAM's files has different coordinate (hybrid) with NCEP(pressure/sigma) and ECWMF(P=A+B*Ps( 1013.250 hPa )). How to change the U,V,T etc using the NCEP/ECWMF data. Thanks very much. Jeff

 

[tilmes]

Hi Jeff, a similar question was discussed here: https://bb.cgd.ucar.edu/node/1001566 Does this answer your questions?Simone

 

[eaton]

Use pressure as the independent variable for doing the vertical interpolation.  You can compute the pressure field from PS and the specific version of the dimensionless coordinate used for each of the CAM, NCEP, and ECMWF datasets. 

 

[snowyang1988@gmail_com]

Thank U for your help. I know the process from hybrid coordinate to the pressure field, but don't know the reverse process. The initial data uses the hybrid coordinate(P=A*P0+B*Ps). So changing the U or T needs the A and B value. How to compute them? Or you have some advice.Thanks again.

 

[snowyang1988@gmail_com]

hello, Simone. I had read it but could not find the answer. Can you give me a clear method? Thank you for your help

 

[eaton]

You don't compute A or B.  They are fixed values, and you'll find them in any existing initial file.  The A and B values at layer midpoints are in the variables hyam and hybm.  The A and B values at interfaces are in hyai and hybi. 

 

[snowyang1988@gmail_com]

I used the CESM Processor and ncl "vinth2p" to interpolate CESM hybrid coordinates to pressure coordinates. Is there any tools to interpolate pressure coordinates to hybrid coordinates? And then Generate the U/T field to replce the U/T in the former datasets. Is it right?Another question, what is the difference between met_data and ncdata in the cesm/inputedata/atm?