A significant change in sea ice diffuse attenuation coefficient with temperature and its implications for the Arctic Ocean

Abstract

AbstractSea ice transparency is essential to the ecology of the ice‐covered sea. Research suggests that the diffuse attenuation coefficient of downwelling irradiance () varies with ice temperature (); however, the characteristics of its response are not well understood yet, particularly from a quantitative perspective. In an attempt to fill this gap, three independent laboratory experiments were performed between 2016 and 2022 to investigate the variations of with changing . Validation experiments were further performed in Liaodong Bay in 2018 and 2022. To explore the dominant factors controlling this phenomenon, corresponding changes in scattering properties were estimated through a two‐stream radiative transfer model. To examine its implications for local ice algal primary production and radiation transport, of Arctic sea ice was parameterized as a function of . Our results from the laboratory and field experiments showed that decreases (increases) with ice warming (cooling), and a 1°C change in results in a 0.29 m−1 average change in . The response of to between −9°C and −2°C is more notable than that observed between −24°C and −9°C. This is associated with the different variations in the scattering properties of sea ice. It reveals a significant effect on ice algal primary production under severe light‐limited conditions but a weaker effect on radiation transport. Knowledge of this ‐temperature dependence would further improve our understanding of the optical properties of sea ice and the parameterization of ice transparency in large‐scale climate models.