Summertime sea-ice prediction in the Weddell Sea improved by sea-ice thickness initialization

Yushi Morioka,Simona Masina,Doroteaciro Iovino,Swadhin K Behera,Andrea Cipollone

doi:10.1038/s41598-021-91042-4

Abstract

Skillful sea-ice prediction in the Antarctic Ocean remains a big challenge due to paucity of sea-ice observations and insufficient representation of sea-ice processes in climate models. Using a coupled general circulation model, this study demonstrates skillful prediction of the summertime sea-ice concentration (SIC) in the Weddell Sea with wintertime SIC and sea-ice thickness (SIT) initializations. During low sea-ice years of the Weddell Sea, negative SIT anomalies initialized in June retain the memory throughout austral winter owing to horizontal advection of the SIT anomalies. The SIT anomalies continue to develop in austral spring owing to more incoming solar radiation and the associated warming of mixed layer, contributing to further sea-ice decrease during late austral summer-early autumn. Concomitantly, the model reasonably reproduces atmospheric circulation anomalies during austral spring in the Amundsen-Bellingshausen Seas besides the Weddell Sea. These results provide evidence that the wintertime SIT initialization benefits skillful summertime sea-ice prediction in the Antarctic Seas.

Highlights

Where Tm is the mixed-layer temperature, Qnet is the net surface heat flux on the ocean surface, qd is the shortwave radiation that penetrates into the subsurface ocean below the mixed layer[43], ρ is the ocean density, cp is the ocean heat capacity, H is the mixed-layer depth defined as the depth at which the potential ocean density increases by
0.03 kg m−3 compared to that at 10 m depth, um and vm are the zonal and meridional velocities averaged in the mixed layer, T is the differences in the mixed-layer temperature and the subsurface ocean temperature at the depth which is deeper by 20 m than the mixed-layer depth, and we
Res includes vertical/horizontal diffusion and mixings and other unresolved processes

Summary

Introduction

We spun up the SINTEX-F2 model with monthly climatology of the observed SST during 1950–1981. We initialized the model SST with the observed SST every month during 1982–1985. To initialize the model SST, we nudged the model SST to the observed one by applying three negative feedback values (− 2400, − 1200, and − 800 W m−2 K−1) to the surface heat flux.

Results

Conclusion