Why is the 500 hPa geopotential height in the CAM5 simulation results so strange over land?

[Jefuty258]

Why is the 500 hPa geopotential height in the CAM5 simulation results so strange over land? The simulation of geopotential height in CAM6 is closer to ERA5, but due to the bias in CAM6's precipitation results, we have to use CAM5 for the study for now. The geopotential height variable (Z3) in both versions of CAM has been processed using the interp_hybrid_to_pressure function from the Python external library geocat-comp before plotting, and the meteorological input data for both is from MERRA2 (with CAM5 at 1.9x2.5 resolution and CAM6 at 0.9x1.25 resolution).