Improved simulation of Antarctic sea ice due to the radiative effects of falling snow

• Published in: Environmental Research Letters
• Main Authors: J-L F Li, Mark Richardson, Yulan Hong, Wei-Liang Lee, Yi-Hui Wang, Jia-Yuh Yu, Eric Fetzer, Graeme Stephens, Yinghui Liu
• Format: Article in Journal/Newspaper
• Language: English
• Published: IOP Publishing 2017
• Subjects: GCM; sea ice concentration; precipitating ice; sea ice albedo; cloud radiation; CMIP5; Environmental technology. Sanitary engineering; TD1-1066; Environmental sciences; GE1-350; Science; Q; Physics; QC1-999; Antarctic; Southern Ocean; Antarc*; Sea ice
• Online Access: https://doi.org/10.1088/1748-9326/aa7a17; https://doaj.org/article/4248189a2b4b46aea9bc77a01ef8e74e

Southern Ocean sea-ice cover exerts critical control on local albedo and Antarctic precipitation, but simulated Antarctic sea-ice concentration commonly disagrees with observations. Here we show that the radiative effects of precipitating ice (falling snow) contribute substantially to this discrepancy. Many models exclude these radiative effects, so they underestimate both shortwave albedo and downward longwave radiation. Using two simulations with the climate model CESM1, we show that including falling-snow radiative effects improves the simulations relative to cloud properties from CloudSat-CALIPSO, radiation from CERES-EBAF and sea-ice concentration from passive microwave sensors. From 50–70°S, the simulated sea-ice-area bias is reduced by 2.12 × 10 ^6 km ^2 (55%) in winter and by 1.17 × 10 ^6 km ^2 (39%) in summer, mainly because increased wintertime longwave heating restricts sea-ice growth and so reduces summer albedo. Improved Antarctic sea-ice simulations will increase confidence in projected Antarctic sea level contributions and changes in global warming driven by long-term changes in Southern Ocean feedbacks.