This paper presents a new heatwave (HW) detection algorithm that identifies spatially coherent HW patterns on synoptic scales and their temporal evolution, yielding the main characteristics (extension, intensity or persistence) of HW events (HWEs). The algorithm has been applied to temperature data from the ERA-Interim reanalysis in order to derive a catalogue of Iberian HWEs for the extended summers (June to September) of the 1979–2017 period. The results indicate mean frequencies of five Iberian HWEs and 16 summer days with HW conditions over Iberia (Iberian HWDs), with significant positive trends in both diagnostics. The analysis of the life-cycle reveals that more than half of the HWEs correspond to events that originated within the region. Although Iberian HWEs last more than one week on average, they tend to be transient, persisting for about three days in the region (Iberian phase), where they reach maximum intensity and extension, and evolving later to other areas. In order to identify recurrent patterns of occurrence, a clustering of Iberian HWEs was performed based on their mean temperature fields. Four clusters were obtained: Atlantic, Subtropical, European and Mediterranean events, which display distinctive characteristics and spatio-temporal evolution, causing HW conditions in western, southern, northern and eastern Iberia, respectively. Interestingly, Mediterranean events largely explain the overall trends in Iberian HWEs and HWDs.

The connection between Iberian HWEs and atmospheric circulation patterns as summarized in four Weather Regimes (WRs) was also investigated. During the Iberian phase, HWEs are preferentially associated with ridge conditions in western Europe, with small variations in this WR determining different regional HWEs. However, the four types of regional Iberian HWEs tend to occur under different WRs during their pre- and post-Iberian phases, and show different relationships with WRs on seasonal scales. Using an impact-oriented metric for HWEs that accumulates the intensity of HW conditions over the areas affected by the event through its life-cycle, the top 10 Iberian HWEs were identified. They include well-known recent events such as those of August 2003, and June 2017. Flow analogues of the most outstanding Iberian HWEs reveal that recent warming has contributed to double their extension and intensity, making them more exceptional than they would have been in the past.

本文提出了一种新的热波（HW）检测算法，该算法可在天气尺度上识别空间连贯的HW模式及其时间演变，从而得出HW事件（HWE）的主要特征（扩展，强度或持久性）。该算法已应用于ERA-Interim重新分析的温度数据，以得出1979-2017年夏季（6月至9月）的伊比利亚HWE的目录。结果表明，五个伊比利亚HWE的平均频率和16个夏季伊比利亚HW状况（伊比利亚HWD）的平均频率，两种诊断方法均具有明显的积极趋势。对生命周期的分析表明，超过一半的HWE与该区域内发生的事件相对应。虽然伊比利亚的HWE平均可持续超过一周，但它们往往是短暂的，在该地区（伊比利亚阶段）持续了大约三天，在那里它们达到了最大的强度和延伸，后来又发展到其他地区。为了确定复发的发生方式，根据伊比利亚HWE的平均温度场进行了聚类。获得了四个集群：大西洋事件，亚热带事件，欧洲事件和地中海事件，这些事件表现出独特的特征和时空演化，分别导致伊比利亚西部，南部，北部和东部的硬件条件。有趣的是，地中海事件在很大程度上解释了伊比利亚HWE和HWD的总体趋势。根据伊比利亚HWE的平均温度场进行聚类。获得了四个集群：大西洋事件，亚热带事件，欧洲事件和地中海事件，这些事件表现出独特的特征和时空演化，分别导致伊比利亚西部，南部，北部和东部的硬件条件。有趣的是，地中海事件在很大程度上解释了伊比利亚HWE和HWD的总体趋势。基于伊比利亚HWE的平均温度场进行聚类。获得了四个集群：大西洋事件，亚热带事件，欧洲事件和地中海事件，这些事件表现出独特的特征和时空演化，分别导致伊比利亚西部，南部，北部和东部的硬件条件。有趣的是，地中海事件在很大程度上解释了伊比利亚HWE和HWD的总体趋势。

还研究了伊比利亚HWE与大气环流模式之间的联系，总结了四个天气制度（WR）。在伊比利亚阶段，HWE优先与西欧的山脊条件相关，该WR的微小变化决定了不同的区域HWE。但是，四种类型的伊比利亚地区HWE往往在伊比利亚前期和后阶段出现在不同的WR下，并且在季节尺度上显示出与WR的不同关系。使用针对HWE的面向影响的指标，在​​事件的整个生命周期内累积受事件影响区域的HW条件强度，从而确定了伊比利亚十大HWE。其中包括最近著名的事件，例如2003年8月和2017年6月。