Summer season sea surface temperature changes in the Aegean Sea based on 30 years (1989–2019) of Landsat thermal infrared data

Abstract

In this research, sea surface temperature (SST) variability for the summer season in the Aegean Sea was analysed over a period of 30 years by using the Landsat thermal infrared bands. A total of 88 Landsat 5, 7, and 8 thermal infrared satellite images from June, July, and August were used for each year from 1989 to 2019. To estimate SST from the thermal infrared band data, thermal infrared sensor at-sensor spectral radiance, and thermal infrared sensor top-of-atmosphere brightness temperatures were used. SST pixel values were extracted from thermal images for the 3-month summer season of each year. In order to validate the findings, regression analysis was performed between the Mediterranean Sea Ultra High Resolution SST L4 data and Landsat data for the 2008–2019 period. Regression constant R-squared values were found to be 0.9672 for June, 0.9550 for July, 0.9634 for August, and 0.9634 for all summer seasons. It was calculated that the minimum value of the average SST was 18.44 ± 2.87 °C in 1992, and the maximum value of the average SST was 23.45 ± 0.70 °C in 2018. According to the Landsat data, over the past 30 years, the annual average SST changes were estimated to be 0.11 °C, and the total changes of average SST were estimated to be 3.19 ± 1.26 °C. As a result of the analysis and the validation, we can see that there is a rising trend in sea surface temperature in the Aegean Sea. However, it is difficult to determine whether this upward trend is related to global climate change. © 2020, Springer Nature Switzerland AG.