The principal aim of the physical oceanography component of the Marine Climate Change Program is to describe the long-term variability and trends in regional water mass characteristics such as temperature, salinity, and currents, in relation to variability in large-scale dynamical features (e.g., North Atlantic basin-scale gyres and European shelf-edge current) and to shifts in atmospheric forcing.
The dynamics of the water masses in the oceanic region to the west of Ireland is central to the Earth’s climate. When transported northwards into the Arctic Ocean, these water masses influence the rate of deep water formation, which controls the exchange of heat and nutrients across the world ocean, though a mechanism called “the great conveyor belt”. Paleo-climate records demonstrate a relationship between the changes in ocean circulation (the thermohaline circulation) and past shifts in the global climate.
Ireland has been actively monitoring the essential ocean climate variables, such as air and sea temperatures, wind, pressure, and humidity, through the Irish national Research Vessels, Data Buoy Network, and Tide Gauge Network, since 1994. Integrative information for the Irish waters is also available through international programs.
Sea surface temperatures in Irish waters have exhibited a warming trend over the past 100 years, with the four warmest years occurring during the past decade, with 2006 being the warmest year on record. This warming trend is superimposed on strong interannual and decadal scales of variability.
Annual sea surface temperature anomalies in the Irish waters (extracted from the HadSST2 global data set, Rayner et al., 2003) overlain by 5-year running means showing HadSST2 data for 1890-2006 (black), AVHRR satellite sea surface temperature data for 1986-2006 (blue), and a sea temperature time series recorded at Malin Head on the north coast of Ireland from 1958-2006 (red).