ALBERT

Description: The retrieval of Arctic sea ice thickness is one of the major objectives of the European CryoSat-2 radar altimeter mission and the 7-year long period of operation has produced an unprecedented record of monthly sea ice thickness information. We present CryoSat-2 results that show changes and variability of Arctic sea ice from the winter season 2010/2011 until fall 2017. CryoSat-2, however, was designed to observe thick perennial sea ice, while an accurate retrieval of thin seasonal sea ice is more challenging. We have therefore developed a method of completing and improving Arctic sea ice thickness information within the ESA SMOS+ Sea Ice project by merging CryoSat-2 and SMOS sea ice thickness retrievals. Using these satellite missions together overcomes several issues of single-mission retrievals and provides a more accurate and comprehensive view on the state of Arctic sea-ice thickness at higher temporal resolution. However, stand-alone CryoSat-2 observations can be used as reference data for the exploitation of older pulse-limited radar altimetry data sets over sea ice. In order to observe trends in sea ice thickness, it is required to minimize inter-mission biases between subsequent satellite missions. Within the ESA Climate Change Initiative (CCI) on Sea Ice, a climate data record of sea ice thickness derived from satellite radar altimetry has been developed for both hemispheres, based on the 15-year (2002-2017) monthly retrievals from Envisat and CryoSat-2 and calibrated in the 2010-2012 overlap period. The next step in promoting the utilization of sea ice thickness information from radar altimetry is to provide products by a service that meets the requirements for climate applications and operational systems. This task will be pursued within a Copernicus Climate Change Service project (C3S). This framework also aims to include additional sensors such as onboard Sentinel-3 and we will show first results of Sentinel-3 Arctic sea-ice thickness. These developments are the base for preserving the continuity of the sea ice thickness data record and the transformation from research oriented products into an operational service.