Sea ice lead fraction for Arctic from AMSR2 data, November 2012 to April 30 2020@en

Röhrs and Kaleschke (2012) found that thin ice has a unique signature in the emissivity radio in the vertical polarized brightness temperature channels at frequencies between 89.0 GHz and 18.7 GHz in winter. The different sea ice classes especially for water and thin ice are characterized by the emissivity ratios above one. Following the proposed algorithm, we derive sea ice lead fraction from the AMSR2 brightness temperature data for the freezing season (November-April) north of 65°S. The spatial resolution of the data is 6.25 km. The steps are as follows. Firstly, the AMSR2 L1B brightness temperatures at frequencies of 18.7 GHz (TB,18.7V) and 89.0 GHz (TB,89V) are interpolated onto the NSIDC EASE grid with a spatial resolution of 6.25 km. Secondly, the brightness temperature radio r=TB,89V/TB,18.7V is calculated. Thirdly, a mean filter is used to enhance the signal of the leads. Finally, lead fraction which is defined as the area fraction of thin ice compared to other ice classes is computed. The proposed algorithm exhibits advanced ability in detecting sea ice leads in pack ice zone. It can detects leads wider than 3 km and resolves about 50% of the lead area compared to MODIS satellite images. […]