Arctic sea ice density observation and its impact on sea ice thickness retrieval from CryoSat–2

Abstract

Sea ice density is an important physics parameter for the climate models, and is a critical parameter for the retrieval of sea ice thickness (SIT) from satellite altimeters. In the context of rapid Arctic sea ice changes, the value of sea ice density may need to be adapted for SIT retrieving from satellite radar altimeters. In this study, we collected in situ sea ice density measurements from various literatures for the period between 2000 and 2015, and carried out spatio–temporal variability analyses. We then applied Ordinary Kriging interpolation technique on sea ice density distribution and calculated SIT based on a static equilibrium equation. The impact of sea ice density on retrieved SIT from CryoSat-2 altimeter was assessed. The measured sea ice density during 2000–2015 varies between 675 kg·m−3 and 954 kg·m−3, which indeed has a wider range than the values measured before 21 century. Monthly mean sea ice density in the Arctic varies between 832 kg·m−3 (August) and 916 kg·m−3 (February). The difference between CryoSat-2 derived SIT and buoy-measured SIT reduced from 24 ± 11 cm when using fixed ice densities to 7 ± 3 cm when using sea ice densities after data interpolation in March 2012–2015. It is suitable to use updated sea ice density values than to use the traditional fixed values for retrieving Arctic SIT from CryoSat–2. Analysis of Arctic in situ sea-ice density observations and application of them in SIT retrievals could benefit further research on Arctic sea ice and climate change.