During MERRA production, the variable 'SPSNOW' was found to be producing incorrect values, and was patched in the middle of production. Incorrect SPSNOW data occur during the following periods:
19790101-19840101
19890101-19931201
19980101-20011001

SPSNOW is the spurious snow source used to maintain stability and balance in the mass budget. In general, it should be a very small term and is included in the output to provide more accurate water budgets.

This error exists in in the MERRA archive data, but there are plans to correct the files.