What is the grid used ?

For most of our product, we are using the EASE-Grid 2.0 Global (EPSG 6933).

The only exception is for the  L3 Brightness Temperature product in polar projection for which we are using the EASE-Grid 2.0 North (EPSG 6931) and EASE-Grid 2.0 South (EPSG 6932).

References:
A Guide to EASE Grids
EASE-Grid 2.0: Incremental but Significant Improvements for Earth-Gridded Data Sets and correction