The Cryosphere Discussions www.the-cryosphere-discuss.net 1994-0432 1994-0440 4 1 2010 10.5194/tcd-4-183-2010 http://www.the-cryosphere-discuss.net/4/183/2010/ http://www.the-cryosphere-discuss.net/4/183/2010/tcd-4-183-2010.html http://www.the-cryosphere-discuss.net/4/183/2010/tcd-4-183-2010.pdf 183 206 2010-02-22 An algorithm to detect sea ice leads using AMSR-E passive microwave imagery J. Röhrs L. Kaleschke lars.kaleschke@zmaw.de Institute of Oceanography, University of Hamburg, Bundesstraße 53, 20146 Hamburg, Germany Leads are major sites of energy fluxes and brine releases at the air-ocean interface of sea ice covered oceans. This study presents an algorithm to detect leads that are broader than 3 km in the entire Arctic Ocean. The algorithm detected 50% of the lead area that is visible in optical satellite images. Passive microwave imagery from the Advanced Microwave Scanning Radiometer – Earth Observation System (AMSR-E) is used, allowing daily observations that are independent of daylight or cloud conditions. Using unique signatures of thin ice in the brightness temperature ratio between the 89 GHz and 19 GHz channels, the algorithm allowed to detect thin ice features in the ice cover and is optimized to detect leads. Leads were mapped for the period from 2002–2009 excluding the summer months. Several frequently reoccurring large scale lead patterns were found, especially in regions where sea ice is known to drift out of the Arctic Ocean. The maximum lead occurrence in the Arctic is located in the Beaufort Sea, low lead occurrence was found in the inner Arctic Ocean close to the North Pole. Andersen, S., Tonboe, R., Kaleschke, L., Heygster, G., and Pedersen, L.: Intercomparison of passive microwave sea ice concentration retrievals over the high-concentration Arctic sea ice, J. Geophys. 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