To compensate for the lack of conventional observations over the Arctic Ocean, ship-borne radiosonde observations have been regularly carried out during summer Arctic expeditions and the observed data have been broadcast via the global telecommunication system since 2017. With these data obtained over the data-sparse Arctic Ocean, observing system experiments were carried out using a polar-optimized version of the Weather Research and Forecasting (WRF) model and the WRF Data Assimilation (WRFDA) system to investigate their effects on analyses and forecasts over the Arctic. The results of verification against reanalysis data reveal: (1) DA effects on analyses and forecasts; (2) the reason for the year-to-year variability of DA effects; and (3) the possible role of upper-level potential vorticity in delayed DA effects. The overall assimilation effects of the extra data on the analyses and forecasts over the Arctic are positive. Initially, the DA effects are the most apparent in the temperature variables in the middle/lower troposphere, which spread to the wind variables in the upper troposphere. The effects decrease with time but reappear after approximately 120 h, even in the 240-h forecasts. The effects on forecasts vary depending on the proximity of the radiosonde observation locations to the high synoptic variability. The upper-level potential vorticity is known to play an important role in the development of Arctic cyclones, and it is suggested as a possible explanation for the delayed DA effects after about 120 h.

中文翻译：

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船载无线电探空仪观测对北极极地 WRF 预报影响的多年评估

为了弥补北冰洋常规观测的不足，在夏季北极考察期间定期进行船载无线电探空仪观测，并自2017年起通过全球电信系统广播观测数据。在稀疏的北冰洋，利用极地优化版本的天气研究和预报（WRF）模型和WRF数据同化（WRFDA）系统进行了观测系统实验，以研究它们对北极分析和预报的影响。再分析数据验证结果表明：（1）DA对分析和预测的影响；(2) DA效应逐年变化的原因；(3) 高层位涡在延迟 DA 效应中的可能作用。额外数据对北极分析和预测的总体同化效果是积极的。最初，DA 效应在对流层中/下层的温度变量中最为明显，随后扩展到对流层上层的风变量。影响随着时间的推移而减弱，但在大约 120 小时后重新出现，即使在 240 小时的预测中也是如此。对预报的影响取决于无线电探空仪观测位置与高天气变化的接近程度。众所周知，高层位涡在北极气旋的发展中发挥着重要作用，并被认为可以解释约 120 小时后延迟的 DA 效应。