Are Atmospheric Situations Now More Favourable for Heavy Rainfall in the Spanish Mediterranean? Analysis of Episodes in the Alicante Province (1981–2020)

Abstract

Intense rainfall (≥100 mm/24 h) constitutes the most frequent atmospheric hazard on Spain’s Mediterranean coast; this phenomenon causes serious damage to property and kills or injures inhabitants. The Intergovernmental Panel on Climate Change, in its latest report in 2022, indicates that in the current climate change scenario, these episodes will become more frequent, hence the importance of analysing and characterising them. The present paper analysed intense rainfall episodes in the central sector of the Spanish Mediterranean coast (province of Alicante) in the 1981–2020 period. A total of 129 episodes were identified which have affected different areas of this province. The rainfall events were analysed by means of three synoptic classification methods subjective/manual and objective/automatic in order to assess the strengths and weaknesses of the two modalities. The main objective was to identify the most favourable atmospheric situations triggering intense rainfall in the study area. The period with the highest propensity for these episodes to develop was identified, as well as the geographical areas most affected in the study period. Autumn concentrates the biggest amount of intense rainfall episodes throughout the year. Herein, we attempt to demonstrate the relationship between atmospheric situation, accumulated rainfall volume, geographical area affected, and the most favourable period of the year for the development of these events. The main results of the synoptic analysis of extreme events show the coincidence, in the three classification methods used, that the existence of instability in the middle and upper layers of the atmosphere (DANA and troughs) and humid and warm E and NE surface flows are decisive. In addition, the warming recorded in the waters of the western Mediterranean in recent decades is related to extreme events.