missing fields in opendata

[wxdtiefox354]

I tried to use --input opendata option to run the graphcast model in ai-models. The program was able to download sfc and pl grib2 data for two consecutive times that are 6hr apart. But the geopotential and geopotential_at_surface are both missing in the downloaded files. After some digging, apparently the opendata use "gh" as the variable name for geopotential, but ai-models-graphcast uses "z" as the variable name for that. The fix seems to be straightforward. But I still cannot obtain the geopotential_at_surface field as it is not available in the opendata grib2 files. Is there a way to go around this? Has anyone been able to run ai-models-graphcast with opendata? Thanks.