| Summary: | We investigate the potential of a synergetic combination of data from European Space Agency's (ESA) Soil Moisture and Ocean Salinity (SMOS) and Earth Explorer Opportunity Mission-2 (CryoSat-2) mission for sea ice thickness retrieval. SMOS and CryoSat-2 provide complementary information because of their different spatiotemporal sampling and resolution, and because of the complementary uncertainty due to the fundamental difference of the radiometric and altimetric measurement principle. The main limitations of the ice thickness retrieval depend on the emission e-folding depth and the vertical resolution of the effective radar pulse-length, respectively. It is shown that the combination of SMOS and CryoSat-2 considerably reduces the uncertainty with respect to the products derived from the single sensors. The root-mean-square (RMS) error is reduced from 76 to 66 centimeters (cm) and the squared correlation coefficient increases from 0.47 to 0.61 in comparison to validation data of National Aeronautics and Space Administration's (NASA) Operation IceBridge campaign, 2013. Furthermore, we demonstrate the applicability of the Optimal Interpolation method for the generation of a combined product based on weekly CryoSat-2 averages. The combination of CryoSat-2 and SMOS data sets can be used to achieve improve sea ice thickness information and the update rate of Arctic wide maps. This is based on the fact that CryoSat-2 is designed for ice thickness retrieval for thicknesses above 1 meter (m) while SMOS delivers accurate thin ice thickness information. The combination of both datasets is based on a statistical approach (optimal interpolation), which merges weekly information from CryoSat-2 and SMOS from the Alfred Wegener Institute based on the respective uncertainties for different thickness classes. The joint product was developed within the ESA project SMOS+ Sea Ice. The merging of CryoSat-2 und SMOS data was funded by the ESA project SMOS+ Sea Ice (4000101476/10/NL/CT and 4000112022/14/I-AM) and data from DATE to DATE were obtained from https://www.meereisportal.de (grant: REKLIM-2013-04). Ricker, R.; Hendricks, S.; Kaleschke, L.; Tian-Kunze, X.; King, J. and Haas, C. (2017), A weekly Arctic sea-ice thickness data record from merged CryoSat-2 and SMOS satellite data, The Cryosphere, 11, 1607-1623, doi:10.5194/tc-11-1607-2017.
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