Monitoring main ocean currents of the Iberia–Biscay–Ireland region

Abstract. The Iberia–Biscay–Ireland (IBI) region is located on the eastern margin of the North Atlantic. This geographical position results in a diverse array of currents, primarily including southward surface currents (associated with the North Atlantic subtropical gyre) and poleward slope currents at intermediate depths following the continental margins of Africa and Europe. Ocean currents have significant climatic, environmental, economic, and social implications, making them a crucial parameter whose variability needs to be monitored to anticipate diagnosis and support decision-making in the face of changing scenarios. The present study proposes a methodology that allows for systematic monitoring of ocean currents. This methodology is based on calculating volume transports within monitoring windows defined using (i) present knowledge of the ocean and (ii) delineation of the water mass to be monitored based on its density range. The proposed indicator is computed using various sources of observational and modeling data, resulting in a multi-product output. This approach provides not only an ocean monitoring indicator (OMI) of transport anomalies but also an analysis of uncertainties. The calculation of this OMI on the currents in the IBI region shows that, despite the high uncertainties, the index is capable of detecting events of high and low transport intensity as well as significant transport trends superimposed on the interannual variability of some of the analyzed currents.