Medium-range predictability of early summer sea ice thickness distribution in the East Siberian Sea: Importance of dynamical and thermodynamic melting processes
Medium-range predictability of early summer sea ice thickness distribution in the East Siberian Sea: Importance of dynamical and thermodynamic melting processes
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东西伯利亚海初夏海冰厚度分布的中期可预测性：动力学和热力学融化过程的重要性
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发表时间：
2018
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通讯作者：
N. Otsuka
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作者：
T. Nakanowatari;J. Inoue;Kazutoshi Sato;Laurent Bertino;Jiping Xie;M. Matsueda;A. Yamagami;Takeshi Sugimura;H. Yabuki;N. Otsuka
北冰洋夏季海冰的加速消退使人们的注意力集中在北海航线（NSR）的潜在用途上，因为海冰厚度（SIT）信息对海上安全航行至关重要。基于TOPAZ4冰海资料同化系统，评价了初夏（6 ~ 7月）东西伯利亚海SIT分布的中期（提前期小于10 d）预报能力。将运行模式SIT数据与所有现有观测数据（原位和卫星）进行比较，结果表明，TOPAZ4再分析再现了观测到的季节周期以及ESS中SIT的推进和融化速度，平均偏差约为±20 cm。对2013-2016年4年SIT预报资料的模式相关分析表明，对初夏SIT分布的预测能力可达3 d，但在第4 d后预测能力急剧下降，这与天气尺度大气波动控制的动力过程有关。如果提前期较长（约4天），则热力学熔化过程将占据主导地位，这使得大部分剩余的预测技能成为可能。2014年7月，在一次冰阻塞事件发生期间，在ESS上模拟了相对较厚的SIT（约150 cm），这与船舶速度的降低一致。这些结果表明，TOPAZ4海冰信息在通过北极航道的夏季海上航行中具有很大的实际应用潜力。
Accelerated retreat of Arctic Ocean summertime sea ice has focused attention on the potential use of the Northern Sea Route (NSR), for which sea ice thickness (SIT) information is crucial for safe maritime navigation. This study evaluated the medium-range (lead time below 10 days) forecast skill of SIT distribution in the East Siberian Sea (ESS) in early summer (June–July) based on the TOPAZ4 ice ocean data assimilation system. Comparison of the operational model SIT data to all available observations (in situ and satellite) showed that the TOPAZ4 reanalysis reproduces the observed seasonal cycle and the rates of advance and melting of SIT in the ESS, with average bias of approximately ±20 cm. Pattern correlation analysis of the SIT forecast data over 4 years (2013–2016) reveals that the early summer SIT distribution is skillfully predicted for a lead time of up to 3 days, but that the prediction skill drops abruptly after the 4th day, which is related to dynamical process controlled by synoptic-scale atmospheric fluctuations. For longer lead times (> 4 days), the thermodynamic melting process takes over, which makes most of the remaining prediction skill. In July 2014, during which an ice-blocking incident occurred, relatively thick SIT (approximately 150 cm) was simulated over the ESS, which is consistent with the reduction of vessel speed. These results suggest that TOPAZ4 sea ice information has a great potential for practical applications in summertime maritime navigation via the NSR.