Behaviour of Temperature Variations in Subsurface Layers in the South-Eastern Mediterranean Sea

Abstract

The present work is a qualitative research, which aims at drawing the general behaviour of variations in the subsurface seawater temperatures within three distinctive subsurface layers in the south-eastern Mediterranean region. The work is based on hydrographic data collected over 65 years (1948–2012). The investigated layers are the subsurface, the intermediate and the deep water layers. The general trend of the mean annual temperature anomaly (MATA) was examined using the linear and quadratic regressions. Results revealed that the MATA over the water column in the south-eastern Mediterranean has the same trend, regardless of the place (layer) of investigation. Linearly, all MATA have increasing trends with different rates, with the exception of the 75 m level, which has a decreasing trend following that previously concluded for the surface water in the region. Also, the quadratic approach reflects the same trend of MATA over the water column, with different years of minimum occurrence. These same trends from the surface to deep can be attributed to the vertical convection processes in this region, and to the expanded impact of solar radiation which may reach more than 30 m depth. Keywords: South-eastern Mediterranean Sea, seawater temperature, linear regression, quadratic regression, cyclic trend