ABSTRACT

Operational seasonal to interannual forecasting systems are in continued development around the world. Various studies have applied models to the dynamical forecasting of sea ice, particularly in the Arctic. The Antarctic, however, has received relatively little attention, with few previous endeavours to quantify operational forecast skill of sea ice. This study assesses sea ice extent prediction skill of the Canadian Seasonal to Interannual Prediction System version 2 (CanSIPSv2) in the Pan-Antarctic domain as well as in various sectors of the Southern Ocean. The forecast skill of GEM-NEMO, one of two constituent models that together comprise CanSIPSv2, is found to generally exceed that of the other, CanCM4i. This difference is potentially due to substantial model drift of sea ice extent away from observations in CanCM4i, in addition to their different initializations of sea ice thickness. Both models show significant forecast skill exceeding that of an anomaly persistence forecast. Prediction skill was found to vary substantially across different sectors of the Southern Ocean. Moreover, our analysis also finds that CanSIPSv2 forecast skill in the Antarctic shows a dependence on time period, demonstrating generally lower skill than seen in the Arctic over the years 1980–2010, in contrast to generally higher skill than in the Arctic over the years 1980–2019.

摘要

世界各地正在持续开发可操作的季节性到年际预报系统。各种研究已将模型应用于海冰的动态预测，特别是在北极。然而，南极洲受到的关注相对较少，之前很少有人尝试量化海冰的业务预报技能。本研究评估了加拿大季节到年际预测系统​​版本 2 (CanSIPSv2) 在泛南极地区以及南大洋各个区域的海冰范围预测技能。GEM-NEMO 是构成 CanSIPSv2 的两个组成模型之一，其预测能力普遍超过另一个模型 CanCM4i。这种差异可能是由于海冰范围的模型偏离 CanCM4i 中的观测结果造成的，除了它们对海冰厚度的不同初始化之外。两种模型都显示出超过异常持续性预测的显着预测技巧。研究发现，南大洋不同区域的预测能力存在很大差异。此外，我们的分析还发现，南极地区的 CanSIPSv2 预报技能显示出对时间段的依赖性，表现出 1980 年至 2010 年北极地区的预报技能普遍较低，而 1980 年北极地区的预报技能普遍高于 1980 年北极地区的预报技能–2019。