Heat Storage as Evidence of Hydrographic Cycles in the Southeastern Mediterranean Basin

Abstract

Numerous studies were conducted in the Southeastern Mediterranean Sea to determine whether variations in the hydrography and fisheries exhibit cyclic behaviour. This work investigated the long-term cyclic behaviour of physical properties in the Southeastern Mediterranean basin; taking heat storage as a parameter of interest. Heat storage is said to be a more accurate component to measure the probable thermal cyclic behaviour within a specific basin; it allows for the elimination of diurnal (full) and monthly effects on the examined thermal behaviour to a lesser extent. The work aims to: (1) provide the best fit model of heat storage anomaly changes; and (2) investigate any cyclic behaviour of change over a considerable span. The hydrographic data (temperature and salinity) were scattered over the period 1889-2021. However, because of the scarcity of data over the period 1892-1964, calculations of the mean annual heat storage and mean annual heat storage anomaly focused on the period 1965-2021 of continuous records. The minimum mean annual heat storage anomaly of the 300 m layer ranged from -9.0E9 Jm-2 (1992) to +0.84E9 Jm-2 (1994), with an overall mean of -0.016E9 Jm-2. +0.43E9 Jm-2 was the standard deviation from the mean. The best fit model was produced for the variations in the mean annual heat storage anomaly. This was represented by a cubic equation with R2 of 0.21. The minimum anomaly occurred in 1980 and the maximum in 2015. Therefore, the results confirmed the 70-year cycle of variation in the hydrographic conditions in the south-eastern Mediterranean region. Keywords: Southeastern Mediterranean Sea, heat storage, anomalies, cycles