Add Urea units [NMOL/L]

[asdossant]

Urea data has been submitted with units of nM for cruise 49NZ20191229, but currently our parameters table only has UMOL/KG.
We decided to add Urea with units of NMOL/L (or UMOL/L) to the parameter table

Link to cruise with submitted data:
https://cchdo.ucsd.edu/cruise/49NZ20191229

[DocOtak]

I have been unable to find an instance where we have mixed SI prefixes (nano vs micro in this case). So I really hesitate to add NMOL units without making a decision about converting either the incoming data or all the existing data (like 5 cruises). Is the UMOL/L in parens a suggestion that we would be open to converting (by dividing by 1000) the incoming data?

I poke around NVS and UMOL units seem to be what they have for urea params. All of our existing data are in UMOL/KG so UMOL/L feels natural/correct, even if the numbers are small <1.