Erik Kluzek

There aren't very many references so easy to do: ``` shell cime_config/buildnml: "clm4_5_ERA5": "clm4_5_CRUv7", cime_config/buildnml: "clm5_0_ERA5": "clm5_0_GSWP3v1", cime_config/buildnml: "clm6_0_ERA5": "clm6_0_GSWP3v1", cime_config/config_component.xml: ERA5 (not tuned) cime_config/config_component.xml: cime_config/config_component.xml: clm5_0_cam6.0,clm5_0_cam7.0,clm5_0_cam5.0,clm5_0_cam4.0,clm5_0_GSWP3v1,clm5_0_CRUv7,clm5_0_QIAN,clm5_0_1PT,clm5_0_NLDAS2,clm5_0_ERA5,clm4_5_CRUv7,clm4_5_GSWP3v1,clm4_5_QIAN,clm4_5_cam6.0,clm4_5_cam7.0,clm4_5_cam5.0,clm4_5_cam4.0,clm4_5_1PT,clm4_5_NLDAS2,clm4_5_ERA5,clm6_0_CRUv7,clm6_0_GSWP3v1,clm6_0_cam6.0,clm6_0_cam7.0,clm6_0_cam5.0,clm6_0_cam4.0,clm6_0_QIAN,clm6_0_1PT,clm6_0_NLDAS2,clm6_0_ERA5 cime_config/config_component.xml: cime_config/config_component.xml: clm4_5_ERA5...

ERA5 is desired, so we want to keep it around, but will update based on Sean's work so it works correctly.

@swensosc could you point us to a case you have working with ERA5?

> @ekluzek / @swensosc - Wondering if there's an update on this? Finally looking to start some ESPAT runs that use ERA5 forcing to spin up offline CLM. Do we...

This will close when the cleanup branch comes to master.

I started a document for this here: https://docs.google.com/document/d/1TgfWW6oTfiPfK9XREiHYpz2-ZBVO9YYqdOWVUe4HFMo/

Part of the reason to do this is because of the problems I saw in #2545. The other is to keep up to date with cesm3_0 submodules in CESM tags

Also note that @fischer-ncar found that a new ccs_config is needed for the setup to build, so at least that submodule will change. We'll let him figure this out first.

This relates to #2654 another difference in cesm3_0_alpha02a is the removal of MCT and adding in: libraries/mpi-serial for MPIserial_2.5.0

I looked into this a bit, but it will take some effort to get the PF unit-testers to work with the removal of esmf_wrf_timemgr in the share code. This will...