Spatio-temporal variability of sea surface temperature in Irish waters (1982-2015) using AVHRR sensor

- Irish waters present a warming trend of 0.3 °C decade− 1.
- SST trends presented spatial heterogeneity in Irish waters.
- Warming was more intense in autumn.
- SST trends are influenced by natural variability and anthropogenic effects.

Temporal and spatial variability of Sea Surface Temperature (SST), a key variable linked to climate change, was analysed using a continuous 34-year time series of Advanced Very-High-Resolution radiometer (AVHRR) data (1982-2015). The climatological analysis showed a significant latitudinal SST gradient; waters were warmer in the south and colder in the north. A seasonal effect was evident, with lowest SST values in March and highest SST in August. Results suggest that the temporal and spatial variability in Irish waters is mainly related to the Atlantic Multi-decadal Oscillation (AMO) and the warming from anthropogenic CO2 emissions. Overall, the warming trend was significant (p-value of ≤ 0.05) and positive (0.26 °C decade− 1) for the whole study area. However, this trend was not spatially homogeneous and varied between the International Council for the Exploration of the Seas (ICES) Divisions, having the most significant positive trends in the north (VIa, VIb, VIIb and VIIc) and east (VIId and VIIe). Seasonal SST trends were similar to the annual trends but warming was more intense in the autumn.