Analyzing trend and heatwaves of 15 Years of Sea Surface Temperature Variations along the Italian Adriatic Coast.

Water temperature is a vital parameter impacting the growth and survival of aquatic life. Using satellite-derived infrared data, this study analysed the trend of sea surface temperature (SST) from 2008 to 2022 of the Adriatic coastal waters of Italian regions. The "Mediterranean Sea High Resolution and Ultra High Resolution Sea Surface Temperature Analysis" product collected from the Copernicus Marine Service of European Copernicus programme was used, as a good compromise among spatial accuracy, temporal frequency and coverage. SST were derived in 176 locations, placed in the Adriatic Sea from the southern limit of the lagoon of Venice (Veneto) to Santa Maria di Leuca (LE), at a distance from the coast between 500 m and 5000 m (0.3 - 2.7 nautical miles). Time series analysis was applied to average value of daily SST calculated from the selected spatial locations to identify the additive model components: trend, seasonality and random effects. The trend component was isolated and assessed using a linear regression model to determine its significance and magnitude. A 0.010 °C/year increase in SST was observed. Additionally, marine heatwaves and cold spells were consistently registered throughout the entire observation period, with a north-south gradient in intensity.