A manuscript titled “A Climate Data Record of Sea Ice Age Using Lagrangian Advection of a Triangular Mesh”, led by Anton Korosov (NERSC, and leader of WP200), has recently been submitted to Earth System Science Data (ESSD). It presents an improved method to produce fractional sea-ice age classes in the Arctic. The approach traces ice parcels on a Lagrangian triangular mesh, reducing numerical diffusion and enabling improved spatial resolution compared with earlier Eulerian methods. The work represents a great step forward for WP200, subtask 2.2 (Lagrangian sea-ice age), where the focus is on advancing existing algorithms to generate more accurate and continuous fields of ice age. The submitted paper not only documents the scientific basis of the improved algorithm but also provides openly available code and a full data record for 1991-2024.
Sea-ice age class estimates
A key new contribution is the inclusion of detailed uncertainty estimates for each sea-ice age class. These estimates account for uncertainties in both sea-ice concentration and drift, and grow realistically with increasing ice age due to cumulative advection errors. This addition strengthens the dataset’s value for climate applications, as users can now assess the reliability of the fields and use them in assimilation, model evaluation, and trend analysis with quantified confidence.Additionally, the underlying advection fields generated by the Lagrangian scheme can be used to reduce false multiyear ice detection from passive microwave (PMW) and scatterometer (SCAT) observations in subtask 2.3. The manuscript is available at https://doi.org/10.5194/essd-2025-477. Figure 8 from the manuscript is shown below to display the results of the new sea-ice age product and the different components included in the uncertainty estimates (uncertainties from sea-ice concentration (SIC) and sea-ice drift (SID)).
