The impact of stochastic sea ice perturbations on seasonal forecasts

Strommen, Kristian; Mayer, Michael; Storto, Andrea; Spaeth, Jonas; Tietsche, Steffen

doi:10.5194/wcd-7-1593-2026

Articles | Volume 7, issue 3

https://doi.org/10.5194/wcd-7-1593-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/wcd-7-1593-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 7, issue 3

Research article

| Highlight paper

|

31 Aug 2026

Research article | Highlight paper |

| 31 Aug 2026

The impact of stochastic sea ice perturbations on seasonal forecasts

Kristian Strommen, Michael Mayer, Andrea Storto, Jonas Spaeth, and Steffen Tietsche

Supplement

https://doi.org/10.5194/wcd-7-1593-2026-supplement

Data sets

ERA5 monthly averaged data on single levels from 1940 to present Hans Hersbach et al. https://doi.org/10.24381/cds.f17050d7

Seasonal forecast with stochastic sea ice, Experiment ID imsu Kristian Strommen et al. https://doi.org/10.21957/4cdz-q265

Seasonal forecast with stochastic sea ice - control counterpart, Experiment ID ikh7 Kristian Strommen et al. https://doi.org/10.21957/z96y-yy85

Editorial statement

This study describes the implementation and evaluation of a stochastically perturbed parameter (SPP) scheme applied to the sea ice component of ECMWF's Integrated Forecast System (IFS). Applying the SPP scheme in seasonal forecasts enhances ensemble spread for both sea ice concentration and thickness by approximately 10%. The study then concisely catalogues atmospheric effects of introducing stochastic sea ice perturbations and shows that they improve seasonal forecast skill beyond the Arctic region, in particular in Europe during winter. Hypotheses are well presented and tested with different experiments, statistical tests, and toy models.