Test run with CFORCE DATM

Members of the Ocean group (Rita, Gokhan and Fred) are bias correcting ERA5 for running G-cases as part of the CFORCE project. It would be good to see if we can leverage some of this work for CLM simulations so we can develop our own 'in house' DATM pipeline that can be updated more regularly.

Rita has done global bias correcting for incoming solar and has methods for correcting other biases over oceans (temperature, humidity, & winds). This may be challenging over land, as the higher resolution of the dataset (quarter degree) introduces greater topographic heterogeneity than many of our datasets. CFORCE is not changing precip over the ocean, but acknowledges there are precip biases over land (rain bombs in Africa).

@olyson, to start with I wonder if you can take a stab at doing a relatively short SP run on with the current CFORCE data?
@swensosc may have some experience here that's helpful (see also #3010)
@megandevlan is interested in helping to evaluate the forcing (and eventually simulations), as ESPAT is interested in using this.

There are some interesting questions to consider here, especially related to:
- Performance (hourly data at quarter degree).
- Potentially removing multiple streams in the DATM field, as temporal interpolation may not be needed)
- Ability to get direct and diffuse incoming shortwave radiation?
- Mesh file generation (#3010 mentions challenges running at the poles)?
- Methods for bias correcting this higher spatial resolution fields.

Rita stressed this is a work in progress, but her current files are here `/glade/campaign/cgd/oce/people/rita/ERA5/` and said she'd help navigate what files to use