Algorithm Input and Output Data Definition (IODD)

The processing starts from a recent SIC map (in swath projection). Land-mask information should be contained in the SIC map. Land is removed before processing and while a flag for ice-free ocean can be used, those pixels would be retrieved as 0 cm in any case. The input for the ice thickness consists of \(T_{b,h}\) and \(T_{b,v}\) at 1.4 GHz and their uncertainties (currently NeΔT) which are assumed Gaussian noise in this retrieval. The corresponding output is thickness of thin sea ice.

Input data

Field	Description	Shape/Amount
L1B TB	L1B Brightness Temperature at L-band (both H and V polarization)	full swath or section of it (Nscans, Npos)
L1B NeΔT	Random radiometric uncertainty of the channels	full swath or section of it (Nscans, Npos)
sea-ice and land mask	A recent sea-ice concentration field including land information	SIC and land-mask collocated to swath.

Output data

The ouput is in EAES2 grid of the Northern and Southern Hemispheres at 12.5 km.

Field	Description	Shape/Amount
L2 SIT	Sea Ice Thickness	1440x1440
SIT uncertainty	The total Sea Ice Thickness uncertainty	1440x1440
Status Flag	A flag indicating status of retrieval, e.g. “nominal”, “over land”, “ice-free”, “50+cm”	1440x1440

The status flags are defined as follows:

bit	Description
1	Nominal
2	Over land
3	Ice-free
4	50+cm

Note: no specific land mask is applied to the data, only the status flags will indicate over land areas. Over ice-free ocean, the SIT will be 0 cm.

Auxiliary data

Auxiliary data are used to improve the retrieval. They are not mandatory, but the retrieval will be less accurate without them. This includes the masks for filling shelf and land areas. While Land areas are assumed fixed, shelf ice is changing over time, in particular pronounced in the Antarctic. The shelf ice mask is used to exclude shelf ice from the retrieval. The land mask is used to exclude land areas from the retrieval. The CIMR sea ice concentration product may be used for masking.