Super Typhoon Mangkhut (2018) was the most high-impact typhoon in 2018 because of its long lifespan and significant intensity. The operational track forecasts in the short-to-medium range (deterministic and probabilistic forecast) showed a great uncertainty and the forecast landing points varied with different lead times. This study applied ensembles of high-resolution ECMWF forecasts to investigate the major factors and mechanisms of the bias production of the Mangkhut forecast track. The ensembles with the largest track bias were analyzed to examine the possible bias associated factors. The results suggested that environmental steering flows were the main cause for the erroneous southward track error with a variance contribution of 72%. The tropical cyclone (TC) size difference and the interaction of the TC with the subtropical high (SH) were other two key factors that contributed to the track error. Particularly, larger TCs may have led to a stronger erosion of the southern part of the SH, and thus induced significant changes in the large-scale environment and eventually resulted in an additional northward movement of TC.

中文翻译：

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基于集成的超级台风山竹（2018）的轨道误差诊断

超级台风Mangkhut（2018）由于其寿命长且强度大，是2018年影响最大的台风。中短期范围内的运行轨迹预测（确定性和概率性预测）显示出很大的不确定性，并且预测着陆点随交货时间的不同而变化。这项研究应用高分辨率ECMWF预报合奏来研究Mangkhut预报轨道偏差产生的主要因素和机理。分析了具有最大轨迹偏差的合奏，以检查可能的偏差相关因素。结果表明，环境转向流是造成错误的向南航迹误差的主要原因，其方差贡献为72％。热带气旋（TC）的大小差异以及TC与副热带高压（SH）的相互作用是造成轨道误差的另外两个关键因素。特别是，较大的热带气旋可能导致了上海南部的强烈侵蚀，从而引起了大规模环境的重大变化，并最终导致热带气旋进一步向北移动。