Level-2 product definition

The Level-2b product is the result of the processing from Level-1b brightness temperatures to Level-2b ice thickness. The product is provided in the native grid of the CIMR instrument at L-band frequency, which means it contains 135 samples per scan. Multiplied by the number of scans for each orbit gives the number of retrieved ice thickness values per orbit. The product is provided in NetCDF format and contains the following variables following the CF conventions:

variable name	description	unit	dimensions
sea_ice_thickness	mean ice thickness in given grid cell as per retrieval	m	n_scans * n_samples_earth
sea_ice_thickness standard_error	the standard error as described in Uncertainties	m	n_scans * n_samples_earth
sea_ice_thickness quality_flag	product quality flag	1	n_scans * n_samples_earth

The dimension follow the definition of the original CIMR L1b product.

The quality flag is a 16-bit mask with the following bits:

Bit	Description
0	Validity of the retrieved ice thickness (set for valid)
1	Land mask (set for land)
2	Ice shelf mask (set for ice shelf)
3	Sea ice edge mask (set for sea ice edge)
4	full sea ice cover mask (set for sea ice concentration > 0.90)
5-16	Reserved

The quality flag is an important indicator for users of the product. While for full ice coverage of a grid cell the retrieval gives the best, i.e., lowest uncertainty sea ice thickness results, the retrieval is still valid for lower ice concentrations. The sea ice edge mask is set for grid cells where the retrieval is not valid due to the presence of the sea ice edge. The ice shelf mask is set for grid cells where the retrieval is not valid due to the presence of an ice shelf. The land mask bit is set for grid cells where the retrieval is not valid due to the presence of land. The validity of the retrieved ice thickness is set for grid cells where the retrieval is valid in general, which is the major indicator for users of the product.