Abstract. Already shortly after the successful launch of the European Space Agency satellite Aeolus in August 2018, it turned out that dark current signal anomalies of single pixels (so-called hot pixels) on the Accumulation-Charge-Coupled Devices (ACCDs) of the Aeolus detectors detrimentally impact the quality of the aerosol and wind products potentially leading to wind errors of up to 4 m/s. This paper provides a detailed characterization of the hot pixels which occurred during the first one and a half years in orbit. The hot pixels are classified according to their characteristics to discuss their impact on wind measurements. Furthermore, mitigation approaches for the wind retrieval are presented and potential root causes for the hot pixel occurrence are discussed. The analysis of the dark current signal anomalies reveals a large variety of anomalies ranging from pixels with Random Telegraph Signal (RTS)-like characteristics to pixels with sporadic shifts in the median dark current signal. Moreover, the results indicate that the number of hot pixels has almost linearly increased during the observing period between 2018-09-02 until 2020-05-20 with 6 % of the ACCD pixels affected in total at the end of the period leading to 9.5 % at the end of mission lifetime. This work introduces dedicated instrument calibration modes and ground processors which allowed for a correction shortly after a hot pixel occurrence. The achieved performance with this approach avoids risky adjustments to the inflight hardware operation. It is demonstrated that the success of the correction scheme varies depending on the characteristics of each hot pixel itself. With the herein presented categorization, it is shown that multi-level RTS pixels with high fluctuation are the biggest challenge for the hot pixel correction scheme. Despite a detailed analysis in this framework, no conclusion could be drawn about the root cause of the hot pixel issue.

中文翻译：

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风神卫星上使用的ACCD的暗电流信号测量的特性

摘要。在欧洲航天局于2018年8月成功发射卫星风神之后不久，事实证明，暗电流信号异常是单个像素（所谓的热像素））在风神探测器的累积电荷耦合设备（ACCD）上产生不利影响，影响气溶胶和风产品的质量，可能导致高达4 m / s的风速误差。本文详细介绍了在运行的头一年半期间发生的热像素。根据热像素的特征对热像素进行分类，以讨论其对风测量的影响。此外，提出了缓解风的方法，并讨论了热像素出现的潜在根本原因。对暗电流信号异常的分析揭示了各种各样的异常，范围从具有类似随机电报信号（RTS）特征的像素到在中值暗电流信号中具有零星移位的像素。此外，结果表明，在2018-09-02至2020-05-20之间的观察期内，热像素数量几乎呈线性增加，在该阶段结束时，总共有6％的ACCD像素受到影响，从而导致9.5％任务寿命结束。这项工作介绍了专用的仪器校准模式和地面处理器，可以在出现热像素后立即进行校正。通过这种方法获得的性能避免了对机上硬件操作进行危险的调整。已经证明，校正方案的成功取决于每个热像素本身的特性而变化。通过本文提出的分类，表明具有高波动的多级RTS像素是热像素校正方案的最大挑战。