Is it really getting younger? Sea ice type and age in model simulations and satellite remote sensing products

Polona Itkin (Sea Ice Modelling)
Seminar Date: 
16. April 2019 - 11:15 - 11:45
Lecture room, Ground Floor, NERSC

Sea ice type and age are one of the basic indicators of Arctic sea ice state. For a sea ice model to simulate sea ice type or age faithfully, both sea ice dynamics and thermodynamics need to be represented well. In contrast to sea ice thickness, ice age and type have been able to be retrieved from satellite observations relatively reliably for more than a decade. In this study we are using neXtSIM – ‘next generation sea ice model’ that uses Maxwell-elasto-brittle rheology to simulate sea ice motion and a thermodynamical model that accounts for healing of damaged ice through freezing. Previous studies have demonstrated that neXtSIM represents the seasonal cycle of Arctic sea ice well. It was also shown that the model represents the statistical characteristics of sea ice deformation. Here we are presenting the first long – multi-seasonal run with neXtSIM in a stand-alone mode. Our simulation spans from 2000-2017 and encompass the recent rapid decline of the summer and winter sea ice cover in the Arctic. Our comparison to the satellite observations offers an assessment of multitude of conditions that need to be satisfied to obtain realistic simulations (e.g. realistic sea ice drift, melt and export out of Arctic) and reliable remote sensing products (e.g information about degree of ridging and snow cover depth). Our simulations confirm the results from the satellite remote sensing observations about the current prevalence of the first-year ice and second-year ice and new equilibrium state regarding the sea ice thickness and age. We also explore the relationship between the sea ice age that is detectable from space (surface sea ice age) and the true sea ice age (whole column).