[RegCNET] Help with RegCM5 Forcing Height Error in CLM (CM4.5) for Extreme Rainfall Simulation

[. Rohtash]

Dear RegCM Team/ RegCNET,

I am using the RegCM5 model to simulate an extreme rainfall event and am attempting to use hourly ERA5 data as the global forcing for ICBC. I downloaded the ERA5 data using the scripts recommended in the RegCM documentation. I was able to generate ICBC files and start the model, but the simulation stops during CLM initialization with the following error:

The simulation crashes with the following fatal error in mod_clm_canopyfluxes.F90 at line 980:

Error: Forcing height is below canopy height for pft index       194679
 -------------- FATAL CALLED ---------------
  Fatal in file: mod_clm_canopyfluxes.F90 at line:      980
 clm now stopping

Here is the relevant log snippet showing multiple PFTs affected (e.g., 194675-194679, 208291+):

Forcing model :    9.73693417316109
 At pft index       194675
 Canopy height :    12.7399735949002
 Forcing model :    11.9119341731611
 At pft index       194678
 Canopy height :   0.340000000000000
 Forcing model :   -2.18806582683891
 At pft index       194679
 Canopy height :   0.340000000000000
 Forcing model :   -2.18806582683891
Error: Forcing height is below canopy height for pft index       194679

Full log attached if needed.

I have two main questions:

1: What is the recommended way to resolve the "forcing height is below canopy height" error in CLM? Specifically, I would like to understand whether this issue is typically related to: surface dataset generation (mksurfdata), namelist configuration (e.g., forcing height settings), or inconsistencies between atmospheric forcing and land surface parameters.

2: Is there a standard or recommended workflow to make hourly ERA5 input data fully compatible with RegCM5 (particularly for ICBC and land-atmosphere coupling with CLM4.5)?


Any guidance or suggestions would be greatly appreciated. Happy to share my namelists, domain files, or sample ICBC if needed.



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