Daily precipitation extreme events in the Iberian Peninsula and its association with Atmospheric Rivers

Ramos A.M., Trigo R.M., Liberato M.L.R., Tomé R.
Journal of Hydrometeorology

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An automated Atmospheric Rivers detection algorithm is used for the North Atlantic Ocean Basin allowing the identification and a comprehensive characterization of the major Atmospheric River (AR) events that affected the Iberian Peninsula over the 1948-2012 period. The extreme precipitation days in the Iberian Peninsula and their association (or not) with the occurrence of AR is analyzed in detail. The extreme precipitation days are ranked by their magnitude and are obtained after considering 1) the area affected and 2) the precipitation intensity. Different rankings are presented for the entire Iberian Peninsula, Portugal and also for the six largest Iberian river basins (Minho, Duero, Tagus, Guadiana, Guadalquivir and Ebro) covering the 1950-2008 period. Results show that the association between ARs and extreme precipitation days in the western domains (Portugal, Minho, Tagus and Duero) is noteworthy, while for the eastern and southern basins (Ebro, Guadiana and Guadalquivir) the impact of ARs is reduced. In addition, the contribution from ARs towards the extreme precipitation raking list is not homogenous, playing an overwhelming role for the most extreme precipitation days but decreasing significantly as we go to the less extreme precipitation days. Moreover, and given the narrow nature of the ARs, the location of the ARs over each sub-domain is closely related to the occurrence -or not- of extreme precipitation days.