Ensemble forecast experiments of summertime sea ice in the Arctic Ocean using the TOPAZ4 ice-ocean data assimilation system
Ensemble forecast experiments of summertime sea ice in the Arctic Ocean using the TOPAZ4 ice-ocean data assimilation system
复制标题
利用 TOPAZ4 冰海数据同化系统进行北冰洋夏季海冰集合预报实验
DOI：
10.1016/j.envres.2022.112769
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发表时间：
2022
影响因子：
8.3
通讯作者：
Inoue J.
中科院分区：
文献类型：
--
作者：
Nakanowatari T.;Xie J.;Bertino L.;Matsueda M.;Yamagami A.;Inoue J.
精确的海冰厚度信息及其中期（2周）预报对北冰洋海上航行安全至关重要。在这项研究中，我们调查的中期预报技巧的夏季SIT分布在北极边缘海的大气预报数据的敏感性，使用51个成员ECMWF业务集合预报系统（EPS）。针对2015年7月5-6日发生的一次天气尺度气旋事件，从7月1日开始，利用TOPAZ 4冰洋预报系统进行了为期两周的概率预报试验。预报的SIT与气象参数的集合相关分析表明，SIT分布的预报误差对海冰漂移速度敏感，直到1周，这表明真实的海冰漂移改善了海冰厚度的预报。另一方面，超过1周的提前，SIT分布的预报误差是更敏感的地面热通量，而不是海冰漂移。表面热通量信号仅限于海冰边缘区域，其中短波辐射通量与海冰融化过程中SIT的变化有关。海冰边缘短波辐射通量主要由海冰分布决定，海冰分布受天气尺度扰动的影响较大，在较短的预报提前期内准确预报海冰分布间接影响中期预报水平。不同的集合扰动技术的比较表明，预测技巧是更好的，在较短的前置时间（1周），当使用大气EPS，而不是在业务预报系统中使用的随机扰动，但随机扰动是有利的超过1周。因此，EPS的冰-海耦合预报系统的应用，导致更精确的海冰预报中期时间尺度上，我们希望成为实际使用的最佳航运路线在北冰洋。
Precise information on sea ice thickness (SIT) and its prediction at medium-range (2-week) timescale is crucial for the safe maritime navigation in the Arctic Ocean. In this study, we investigate the sensitivity of medium-range prediction skill of summertime SIT distribution in the Arctic marginal seas to atmospheric forecast data, using the 51-member ECMWF operational ensemble prediction system (EPS). For a synoptic-scale cyclone event occurred in July 5–6, 2015, two-week probabilistic forecast experiments were conducted with the TOPAZ4 ice-ocean forecast system, starting on 1st July. The ensemble correlation analysis between the forecast SIT and the meteorological parameters shows that the forecast error of SIT distribution is sensitive to the sea ice drift speed until 1-week, indicating that realistic sea ice drift improves the sea ice thickness prediction. On the other hand, beyond 1 week lead, the forecast error of SIT distribution is more sensitive to surface heat flux rather than sea ice drift. The surface heat flux signal is confined to the sea ice edge region, where the shortwave radiation flux is related to the SIT change through the sea ice melting process. The shortwave radiation flux in the sea ice edge is mostly determined by the sea ice distribution, suggesting that the skillful prediction of sea ice distribution, which is largely affected by synoptic-scale disturbance, at shorter lead times indirectly affects the medium-range forecast skill. A comparison of different ensemble perturbation techniques shows that the prediction skill is better at shorter lead times (up to 1 week), when using an atmospheric EPS rather than the random perturbations used in the operational forecast system, but the random perturbations are advantageous beyond 1 week. Thus, the application of the EPS to an ice-ocean coupled forecast system leads to a more precise sea ice prediction on medium-range timescale, which we expect to become of practical use for the optimum shipping route in the Arctic Ocean.