The snowmelt onset/end data files are in flat binary format. The deimension of the data array is 610 x 380. The data type for the melt onset/end data files are integer*2 (16bit), and -1 for missing data; the data type for the latitude and longitude files are floating point (32bit). 

The microwave-based melt onset/end is only valid for areas north of 50N.  Generally speaking valid MOD should be greater than DOY50.