nicholas_heavens@hamptonu_edu
New Member
I am experiencing a potential bug while running both CESM2 and standalone CLM5. In the case of standalone CLM5, I am running with a 1.1 km grid with topography at that resolution (and all other fields interpolated) in parts of the Andes, East Africa etc. Downscaling of fluxes and ground temperature looks fine. Naively, I'd expect FLDS downscaled to high altitude ice columns of approximately 100 Wm^-2. But there is no difference between the FLDS and FLDS_ICE fields, suggesting something has gone wrong with LW downscaling. (Each grid cell has typically 1% glacier coverage.) There have been no source code modifications from CESM 2.1.1, and the settings for longwave downscaling are in place in lnd_in. It should be no surprise that I think I may be getting more meltwater than appropriate in these simulations.
I have additional concern about this, because this behavior is mostly present in the CLM output file I have from the CMIP6 pre-industrial control for CESM2:
b.e21.B1850.f09_g17.CMIP6-piControl.001.clm2.h0.1100-12.nc
When I calculate FLDS-FLDS_ICE in this file (attached), it is zero over Greenland and Antarctica (and in temperate regions etc.) but something along the margins of Greenland. In other words, longwave downscaling seems to be happening in GLACIER_REGION=1 but not GLACIER_REGION=0,2,3.
Consulting Lawrence et al. (2019) and the relevant CLM5 documentation, I do not see any reason why LW downscaling should be restricted to one glacier_region type. Is this expected behavior? Should longwave downscaling only be happening along the margins of Greenland?
Best regards,
Nicholas G. Heavens, PhD, FGS, FRAS, FRMetS
Research Scientist
Space Science Institute
I have additional concern about this, because this behavior is mostly present in the CLM output file I have from the CMIP6 pre-industrial control for CESM2:
b.e21.B1850.f09_g17.CMIP6-piControl.001.clm2.h0.1100-12.nc
When I calculate FLDS-FLDS_ICE in this file (attached), it is zero over Greenland and Antarctica (and in temperate regions etc.) but something along the margins of Greenland. In other words, longwave downscaling seems to be happening in GLACIER_REGION=1 but not GLACIER_REGION=0,2,3.
Consulting Lawrence et al. (2019) and the relevant CLM5 documentation, I do not see any reason why LW downscaling should be restricted to one glacier_region type. Is this expected behavior? Should longwave downscaling only be happening along the margins of Greenland?
Best regards,
Nicholas G. Heavens, PhD, FGS, FRAS, FRMetS
Research Scientist
Space Science Institute