Abstract
The sea-ice climatology and sea-ice trends and variability are evaluated in simulations with the new version of the coupled Arctic atmosphere-ocean-sea ice model HIRHAM–NAOSIM 2.0. This version utilizes upgraded model components for the coupled subsystems, which include physical and numerical improvements and higher horizontal and vertical resolution, and a revised coupling procedure with the aid of the coupling software YAC (Yet Another Coupler). The model performance is evaluated against observationally based data sets and compared with the previous version. Ensemble simulations for the period 1979–2016 reveal that Arctic sea ice is thicker in all seasons and closer to observations than in the previous version. Wintertime biases in sea-ice extent, upper ocean temperatures, and near-surface air temperatures are reduced, while summertime biases are of similar magnitude as in the previous version. Problematic issues of the current model configuration and potential corrective measures and further developments are discussed.
Highlights
Coupled regional atmosphere-ocean-sea ice models provide the possibility of simulating interactions and feedback between their components which often occur at regional fine spatial and temporal scales that are not resolved by global models
Sea ice, and ocean plays a critical role in the evolution of the Arctic climate system and is likely to be jointly responsible for the climate phenomenon called Arctic Amplification [1]
HIRHAM5 as well as North Atlantic/Arctic Ocean Sea-Ice Model (NAOSIM) can be configured via a number of namelist parameters
Summary
Coupled regional atmosphere-ocean-sea ice models provide the possibility of simulating interactions and feedback between their components which often occur at regional fine spatial and temporal scales that are not resolved by global models. Such feedback between atmosphere, sea ice, and ocean plays a critical role in the evolution of the Arctic climate system and is likely to be jointly responsible for the climate phenomenon called Arctic Amplification [1]. The coupled regional climate model has to rely on the atmospheric and oceanic data used as lateral boundary forcing. This is a particular issue for the lateral ocean boundary
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