A component-based approximation for trend detection of intense rainfall in the Spanish Mediterranean coast

Rainfall behavior is a fundamental issue in areas with scarce and irregular amounts, such as the Spanish Mediterranean region. We identified 12 spatial patterns that characterized 899 torrential precipitation events (≥150 mm in 24 h) that occurred in the 3,537 rainy precipitation series in the period 1950–2020. Three of these components––eastern and ESE––showed positive and significant trends in their accumulated volumes. We then characterized the mean synoptic causes of the 10 most intense events in each component at both mean sea-level pressure and 500 hPa geopotential height, and also the integrated water-vapor transport between 1,000 and 300 hPa. We found a clear spatial distribution of the pluviometric effects related to unstable atmospheric situations (such as troughs and cut-off lows), and also to SW–SE advection fluxes that brought moist air from the Western Mediterranean. In particular, torrential rainfall in the Balearic Islands related more to E–NE advections than to southeastern ones. We also determined that the major parts of these components occurred in early autumn, especially in September and October. We expect these findings to help our understanding of the processes leading to catastrophic situations along the Spanish Mediterranean coast and to lead to improvements in early alert systems and management plans.The authors want to thank the Proyecto UTA-Mayor N° 5807–22 from the Universidad de Tarapacá, Chile. MLC, JMV, PS and OMR want to thank the Climatology Group (2017SGR1362, Catalan Government). RSN is partially supported by the Universidad Autónoma de Madrid (UAM) and the Comunidad de Madrid through project SI3-PJI-2021-00398, the Natural Hazards and Global Change research group from UAM, and the Government of Aragón through the “Program of research groups” (group H09_20R, “Climate, Water, Global Change, and Natural Systems”). JJM and MJE participation has been funded by the Spanish Ministerio de Ciencia e Innovación through the research project PID2020-118797RB-I00 (MCIN/AEI/10.13039/501100011033) and by Generalitat Valenciana through the research project PROMETEO/2021/016 (Conselleria d’Innovació, Universitats, Ciència i Societat Digital)