Analysis of the sea surface temperature variations around Ireland's coastline 2002-2020

Abstract

This thesis analyses the sea surface temperature variations around Ireland’s coastline from 2002-2020, using time series analysis of the one inactive and five currently active marine buoys. In depth analysis of the annual and seasonal sea surface temperature variations were assessed as well as spells of maximum and minimum sea surface temperature for each buoy. Both short term and long-term causations were identified as contributors to the variations in sea surface temperature experienced around Ireland’s coastline. Particular focus on the Atlantic Multidecadal Variability, The NAO Index, the North Atlantic hurricane season and the position of the jet stream were assessed and correlated with sea surface temperature changes around Ireland’s coastline from 2002-2020. These processes are interconnected and display a proportional relationship to each other as there is a high correlation between changes in these processes and a domino effect of other atmospheric and oceanic processes that influence sea surface temperatures around Ireland’s coastline. There were variations in the annual average SST between the buoys. The buoys M4 and M5 both recorded an overall increase in mean annual SST from 2002-2020. Buoys M2, M3 and M6 recorded an overall decrease in the mean annual SST from 2002-2020. No clear connection between the different annual SST trends between the buoys were identified, however their individual location in relation to the continental shelf was a local factor that may have contributed to the variations between the buoys. In depth analysis of the long- and short-term contributors to variations in SST around Ireland’s coastline showed that the most significant influencing factors of SST variations around Ireland’s coastline were the North Atlantic hurricane season track positions and the varying position of the jet stream. Both of these factors displayed a significant impact on the annual SST variations and the spells of either maximum or minimum SST for each buoy. These factors also contributed to changes in the NAO Index, which further influenced SST variations around Ireland’s coastline. The hurricane events contribute to the mixing of waters around Ireland’s coastline, causing unstable conditions and a high level of mixing waters during negative NAO Index occurrences. The AMV signal impacts on air temperature, causing an increase in the effect and frequency of hurricane events in the North Atlantic which influence SST around Ireland’s coastline. Assessment of ongoing changes in the position of the jet stream would be a critical factor in evaluation of future SST variations around Ireland’s coastline.