Ocean climate variability on the western Irish Shelf, an emerging time series

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In an attempt to fill the gap in long-term hydrographic measurements between the well-established sections off Iberia and in the Northern Rockall Trough, Ireland has initiated several standard oceanographic sections in southern Rockall Trough and on the western Irish shelf. The continental shelf west of Ireland is exposed to the open Atlantic Ocean. Fresh water discharges from Irish rivers and those further afield (eg. Loire, Severn) interact with Eastern North Atlantic Water on the Irish shelf to produce the observed circulation pattern. Summer CTD measurements have been made along a section at 53° North on the western Irish shelf since 1999. A long-term gridded climatology is used to discern the mean conditions along this section and anomalies are calculated for the period. Warmer conditions were observed along this section in 2003 and 2004, broadly consistent with other regions of the NW European shelf while cooler conditions were observed in 2001 and 2002. Salinity also exhibits strong inter-annual variability along this section depending on the timing and magnitude of discharges from Irish rivers and rivers in the UK and France. Fresh conditions observed in 2001, 2002 and 2005 are linked to strong discharges from the Loire and Shannon rivers.