Abstract. We develop a new approach to monitor Sudden Stratospheric Warming (SSW) events under climate change since 1980 based on reanalysis data, verified by radio occultation data. We construct gridded daily-mean temperature anomalies and employed the concept of Threshold Exceedance Areas (TEAs), the geographic areas wherein the anomalies exceed predefined thresholds (such as 30 K) to monitor the phenomena. We derived main-phase TEAs to monitor SSW warming on a daily basis and also a trailing-phase TEA to monitor potential upper stratospheric cooling in the wake of the warming phase. Based on the main-phase TEAs, three key metrics, including Main-Phase Strength (MPS), Duration (MPD) and Area (MPA), are estimated and used for the detection and classification of SSW events, enabling minor, major, and extreme event categories. An informative 42 winters’ SSW climatology 1980–2020 was developed, including the three key metrics as well as onsets date, maximum-warming-anomaly location and strength and other valuable SSW characterization information. Detection and validation against previous studies underpins that the new method is robust for SSW detection and monitoring and that it can be applied to any quality-assured reanalysis and observational data that cover the polar region and winter timeframes of interest. Within the 42 winters, 40 SSW events were detected, yielding a frequency of about 0.95/year. In the 1990s, where recent studies showed gaps, we detected several events. About 95 % of event onset dates occurred in deep winter (Dec-Jan-Feb timeframe; about 50 % in January) and three quarters have their onset location over Northern Eurasia and the adjacent polar ocean. Regarding long-term change, we also found a statistically significant increase in the duration of SSW main-phase warmings, by about 4 days from the 1980s to the 2010s, raising the average duration by 40 % from about 10 to 14 days and inducing an SSW strength increase by near 30 million km² days (about 30 %) from about 105 to 135 million km² days. The results can be used as a reference for further long-term studies and be a valuable basis for studying SSW impacts and links to other weather and climate phenomena, such as changes in polar vortex dynamics and in mid-latitude extreme weather.

中文翻译：

---

基于无线电掩星验证的再分析数据监测气候变化下的平流层突然变暖

摘要。我们基于再分析数据开发了一种新的方法来监测自 1980 年以来气候变化下的平流层突然变暖 (SSW) 事件，并通过无线电掩星数据进行了验证。我们构建了网格化的日平均温度异常，并采用了阈值超出区域 (TEA) 的概念，即异常超过预定义阈值（例如 30 K）的地理区域来监测现象。我们推导出主相 TEA 以每天监测 SSW 变暖，还推导出尾相 TEA 以监测变暖阶段之后潜在的上层平流层冷却。基于主相 TEA，估计主相强度 (MPS)、持续时间 (MPD) 和面积 (MPA) 三个关键指标，并用于 SSW 事件的检测和分类，实现次要、主要和极端事件类别。开发了 1980-2020 年 42 个冬季的 SSW 气候学信息，包括三个关键指标以及开始日期、最大变暖异常位置和强度以及其他有价值的 SSW 表征信息。针对先前研究的检测和验证表明，新方法对于 SSW 检测和监测是稳健的，并且它可以应用于涵盖极地和感兴趣的冬季时间框架的任何质量保证的再分析和观测数据。在 42 个冬季中，检测到 40 次 SSW 事件，产生的频率约为 0.95/年。在 1990 年代，最近的研究显示存在差距，我们发现了几个事件。大约 95% 的事件发生日期发生在深冬（12 月至 1 月至 2 月的时间范围；大约 50 % 在 1 月）和四分之三的发病位置在欧亚大陆北部和邻近的极地海洋上空。关于长期变化，我们还发现 SSW 主阶段变暖的持续时间在统计上显着增加，从 1980 年代到 2010 年代增加了约 4 天，将平均持续时间从大约 10 天增加到 14 天，增加了 40%，并导致SSW强度增加近3000万公里²天（约 30%）从约 105 到 1.35 亿公里²天。该结果可作为进一步长期研究的参考，并为研究 SSW 影响以及与其他天气和气候现象的联系提供宝贵的基础，例如极地涡旋动力学和中纬度极端天气的变化。