This data is best interpreted by some type of software (MS Excel, R, Python, etc.)

Daily average ice cover (%) by lake are calculated from gridded ASCII files provided by USNIC and CIS.

Columns correspond to individual ICE years and rows correspond to days of year. Ice years are defined by the January calendar year of a given winter.  (for example, the 1975 column is populated with ice values for Nov '74, Dec '74, Jan '75, and so on.)

NA's indicate that ice cover was NOT recorded on a given day and are therefore distinct from values of zero.