Need to receive Precip and potential ET over lakes from coupler

[ekluzek]

mizuRoute needs to receive Precip and potential ET from the CESM coupler over lakes. When CTSM calculates ET over lakes it assumes lakes have infinite depth so it's really a potential ET. mizuRoute will need to cut it back based on the available water in the lake. Once the lake is dry the actual ET will just be the ET from the soil.

CMEPS issue:

ESCOMP/CMEPS#132

CTSM:

ESCOMP/CTSM#1206

Definition of done:

• Add ability to pass fields in CMEPS
• Make a CMEPS tag
• Add ability to pass it from CTSM, point to the CMEPS tag
• Add ability to receive it in mizuRoute and make a tag for that take into account if potential ET is > lake content
• CTSM tag with updated mizuRoute, CMEPS, and passes it to cpl

Future issue:

• mizuRoute informing CAM/CTSM that ET is less than expected
• And mizuRoute telling CTSM that a given lake is empty, so it should be modeled as bare-soil (doing something similar to the prescribed dynamic lake mode in CTSM)

[ekluzek]

Will be two separate fields.