See summary of corresponding experiment. Model year 1 corresponds to real time year 1860. Years in the GRIB header are being counted from 1-99, 0-55, 0-99, 0-44. This dataset contains 12H values from 01-Jan-1860 to 30-JUL-1909. Time resolution increased (6H values) from 01-AUG-1909 to 30-APR-1920 (in the first block 1-99). Starting from 01-MAY-1920 the dataset contains 12H values.