SMOS-derived thin sea ice thickness: algorithm baseline, product specifications and initial verification

摘要

Following the launch of ESA's Soil Moisture and Ocean Salinity (SMOS)mission, it has been shown that brightness temperatures at a low microwavefrequency of 1.4 GHz (L-band) are sensitive to sea ice properties. Inthe first demonstration study, sea ice thickness up to 50 cm has beenderived using a semi-empirical algorithm with constant tie-points. Here, weintroduce a novel iterative retrieval algorithm that is based on athermodynamic sea ice model and a three-layer radiative transfer model, whichexplicitly takes variations of ice temperature and ice salinity into account.In addition, ice thickness variations within the SMOS spatial resolution areconsidered through a statistical thickness distribution function derived fromhigh-resolution ice thickness measurements from NASA's Operation IceBridgecampaign. This new algorithm has been used for the continuous operationalproduction of a SMOS-based sea ice thickness data set from 2010 on. The dataset is compared to and validated with estimates from assimilation systems,remote sensing data, and airborne electromagnetic sounding data. Thecomparisons show that the new retrieval algorithm has a considerably betteragreement with the validation data and delivers a more realistic Arctic-wideice thickness distribution than the algorithm used in the previous study(Kaleschke et al., 2012).