According to the collection 6 MOD03 documentation the values of the Land/Sea mask refer to.
- 0: Shallow Ocean (Ocean <5k from coast OR <50m deep).
- 1: Land (not anything else).
- 2: Ocean Coastlines and Lake Shorelines.
- 3: Shallow Inland Water (Inland Water < 5km from shore OR < 50m deep).
- 4: Ephemeral (intermittent) Water.
- 5: Deep Inland Water (Inland water > 5km from shoreline AND > 50m deep).
- 6: Moderate or Continental Ocean (Ocean > 5km from coast AND > 50m deep AND < 500m deep).
- 7: Deep Ocean (Ocean > 500m deep).
Water Present is defined as:
High resolution water mask uint8
The low resolution Land/Water mask is filled in by first
extracting a Land/Water mask value for the center of each 500m
pixel, from a source tabulated with 15 arc second resolution,
and then aggregating those values to 1km resolution, giving the
center two pixels doubled weight. This SDS indicates the total
weight of all high resolution water pixels (Land/Water mask
values 0 or 3-7) that were aggregated into the low resolution
NASAs MODAPS website contains information about all MOdis DAta ProductS.