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UP: Fachverband Umweltphysik

UP 3: Kryosphäre

UP 3.6: Talk

Tuesday, March 14, 2017, 14:00–14:15, GW2 B3009

Sea ice concentrations at 1 km resolution from combined optical and passive microwave data — •Valentin Ludwig, Larysa Istomina, and Gunnar Spreen — University of Bremen

Although it covers only about 1.5% of the Earth's surface, Arctic sea ice is a key element of the climate system. The percentage of sea ice within a grid cell (sea ice concentration) is of special importance for various disciplines. For more than 40 years, passive microwave measurements from space have been used for monitoring sea ice in general and sea ice concentration in particular. Their capability to provide year-round daily measurements almost independently of the state of the atmosphere and their good spatial coverage make them a powerful tool for sea ice concentration retrieval. However, they suffer from a coarse spatial resolution of 5 km at maximum. Optical measurements provide higher spatial resolution and complementary errors: while depending on daylight in the visible spectrum and cloud-free conditions in the whole optical spectrum, they come with spatial resolutions of 250 m to 4 km for daily Arctic-wide coverage. We present sea ice concentrations from optical data at a resolution of 1 km and their evaluation against a higher-resolution dataset. The so-derived uncertainty estimates are used to merge optical and passive microwave sea ice concentrations. A multi-year time series is analysed to assess the algorithm's performance throughout the year.