Answer-Changing Features in CESM1_0_4
This page documents changes in cesm1_0_4 that will result in non-bit-for-bit model solutions when compared with cesm1_0_3. Directly below is a summary of compsets that are affected by changes in cesm1_0_4; details can be found in the sections that follow.
- WACCM compsets (see CAM/WACCM)
- E_2000_CN_GLC, E_1850_CN_GLC, F_AMIP_CAM5_CN, F_1850_CN_GLC (see Scripts)
- I compsets, using any of the following domains: T85_T85, T42_T42, T31_T31, f10_f10, f45_45, f19_f19, f09_f09, f05_f05, f02_f02 (see CLM)
- A,C,G,D and I compsets (see "bin 4" discussion in CLM)
- C compsets (see dice)
CAM (Active Atmosphere Model)
- Climate-preserving changes:
- WACCM:
Two bugs were fixed that affect model calculations. First, the incorrect variable had been passed into the gravity wave calculation as the molecular diffusion coefficient. Second, the diffusion solver was using the wrong value as molecular diffusion at the lowest level at which molecular diffusion is turned on (0.55 hPa, ~53 km). The correction of these two bugs produces significant answer changes above 100 km, where molecular diffusion is most significant. In particular, increases in CO2 are significant in the global average above 100 km, with changes increasing with altitude. Additionally, global average temperature decreases significantly between 100 and 120 km, and increases significantly above 120 km.
A third bug was fixed to correct the output values of EKGWSPEC, the effective Kzz diffusion coefficient due to the gravity wave spectrum, which were low by a factor of 2. This bug fix affects only model output for this variable, as the correct value of the diffusion coefficient was being used in model calculations prior to the bug fix.
- Non-climate-preserving changes:
- None
CICE (Active Ice Model)
- Climate-preserving changes:
- None
- Non-climate-preserving changes:
- None
CISM (Active Land-Ice Model)
- Climate-preserving changes:
- None
- Non-climate-preserving changes:
- None
CLM (Active Land Model)
- Climate-preserving changes:
- The domain and fraction datasets were made to be consistent so answers for the following I compset resolutions change: T85_T85, T42_T42, T31_T31, f10_f10, f45_45, f19_f19, f09_f09, f05_f05, and f02_f02.
- Dust wet/dry deposition was mislabeled for bin 4. This changes the coupler history fields and sometimes has a small impact on this DUSTDEP history field in CLM.
- Non-climate-preserving changes:
- Answers for the default I1850SPINUPCN compset changes as the MOAR forcing dataset driving this compset were changed to an appropriate 1850 spinup case.
- The history variables: CISUN, CISHA, ALPHAPSNSUN, and ALPHAPSNSHA were fixed rather than writing out gdir.
- The soil data for PTCLM US-UMB site was corrected.
- A bug in the datm forcing setting for CLM1PT mode was fixed so that it runs in "cycle" mode rather than extrapolating when beyond the available data. This problem caused simulations to be worthless.
POP2 (Active Ocean Model)
- Climate-preserving changes:
- None
- Non-climate-preserving changes:
- None
dice (Data Ice Model)
- Climate-preserving changes:
- bug fix for flux_Qacc -- changes answers for cases using C-type compsets.
- Non-climate-preserving changes:
- None
Scripts
- Climate-preserving changes:
- None
- Non-climate-preserving changes:
- A bugfix was applied to the compset definitions for the following compsets: E_2000_CN_GLC, E_1850_CN_GLC, F_AMIP_CAM5_CN, F_1850_CN_GLC. In each of these compsets, CN should have been activated, but it was not.