Atmospheric Rivers in the Iberian Peninsula: Connection With Extratropical Fronts and Precipitation

Precipitation over the Iberian Peninsula (IP) is highly sensitive to atmospheric rivers (ARs)—long corridors of anomalous horizontal and poleward moisture transport from lower latitudes. This study aims to deepen the understanding of the mechanisms behind Iberian ARs and to quantify their contribution to precipitation over a long-term period. We identify ARs affecting the IP in the ERA5 reanalysis with a 31-km horizontal resolution and covering a 42-year period (1979–2020). Additionally, we explore their association with the fronts of extratropical cyclones. Impact on IP precipitation is evaluated using regional observational gridded products (E-OBS, IB01) and global reanalysis (ERA5). Three AR events (unnamed storm in October 1979, Storm Gong in January 2013, and Storm Ana in December 2017) were selected as case studies and analyzed in detail. During 1979–2020, the IP was affected by 580 persistent ARs (lasting at least 18 hr) with an annual mean of 13.8 ± 2.8 ARs and the northern IP coast being the most affected region. The year 2013 is marked by the highest total number of persistent ARs (20). Cold fronts were found more often in the vicinity of ARs than warm fronts. ... mehrCase studies highlight changes in the relationship between ARs and fronts throughout their lifecycle. Precipitation associated with persistent ARs exhibits a strong north-south gradient in the western IP with the highest contribution to annual precipitation occurring in the northern region (∼30%). Our study demonstrates the important role of ARs in the Iberian precipitation using the latest high-resolution reanalysis and observational data.