2.4 Ice applications: Combined altimetry and radiometry for sea ice classification

Results and comments


Difference of the two brightness temperature normalized, for the Envisat cycle 025 (2004/03/09 - 2004/04/12) over the polar regions.

Backscatter coefficient in Ku-band (ocean retracking) for the Envisat cycle 025 (2004/03/09 - 2004/04/12) over the polar regions.

The distribution of the ΔTBs normalized values displays several structures with negative values (in dark colours), with neutral values(in light-blue colours) and positive values (in red colours). These structures are in accordance with those shown in Tran et al., 2009. Based on clustering method and reference maps, their study describe several sea ice type from Envisat altimetry and radiometry data. By using their conclusion, we can easily retrieve some of these sea ice category over our maps:

ice-free ocean for the highest positive ΔTBs-norm values and the lowest sigma0 values (<10 dB),
multi-year sea ice for the lowest ΔTBs-norm values and low sigma0 values (0-15 dB),
first year sea ice for neutral ΔTBs-norm values and the highest sigma0 values (20-30 dB).

Further information:

Tran, N., Girard-Ardhuin, F., Ezraty, R., Fenf, H., Féménias, P., Defining a Sea Ice Flag for Envisat Altimetry Mission, in IEEE Geoscience and Remote Sensing Letters, Vol. 6, No. 1, January 2009.