The Lena Delta in northern Siberia, covering about 32 000 km2, is the largest delta in the Arctic. It consists of complex geological and geomorphological units incorporating Holocene deltaic deposits, remains of a Late Pleistocene accumulation plain, and several fluvial terrace levels. This polar ecosystem is dominated by polygonal tundra wetlands and features a wide variety of fluvial, ecological, and permafrost-related processes which are investigated by ongoing German-Russian research co-operations since several years.A major focus of the German research by the Alfred Wegener Institute for Polar and Marine Research (AWI) in the Lena Delta is the quantification of carbon budgets and carbon release to the atmosphere and Arctic Ocean related to permafrost and periglacial processes. Tundra wetlands, which are highly sensitive to climate change, are considered major constituents of the global carbon cycle.Since climate models predict outstanding changes in a warming Arctic, considerable impacts on these wetlands are expected. An important step for the quantification of carbon budgets in tundra wetlands and regions of permafrost degradation is the upscaling of local field measurements and field knowledge with remote sensing methods. The generation of such remotely sensed baseline datasets is a precondition for understanding and quantifying present processes and the assessment of possible future changes with change detection approaches. A major achievement for these investigations in the Lena Delta was the earlier generation of a Landsat-7 ETM+ land cover classification of tundra surfaces and vegetation units. The resulting land cover map, covering the entire delta, is based on 10 land cover classes derived from field knowledge and heterogeneously distributed field data.In our approach we focused on the detailed characterization of the surface properties in small key sites of the Lena Delta: Samoylov Island in the central delta and Turakh-Sise Island in the western delta. We conducted field spectrometer measurements (ASD FieldSpec Pro FR) for the in situ recording of spectral properties of tundra surfaces during the field season in summer 2005. The spectra for a wide variety of surface types in the Lena Delta were catalogued and correlations to other parameters (soil data, vegetation data, soil moisture, relief units) were investigated.Additionally, we used multi-spectral Landsat-7 ETM+ imagery, hyper-spectral CHRIS Proba imagery, panchromatic high-resolution CORONA imagery, and digital elevation data for the detailed assessment of land cover, periglacial geomorphology, and other surface properties. Using the information from the investigated key sites we subsequently plan to conduct further investigations: The comparison of our data with the delta-wide Landsat-7 classification and the validation and improvement of its results; the production of a comprehensive, spectral atlas of tundra surfaces in the Lena Delta; and the detection of landscape change by consequently applying the analysis of multi-temporal imagery.