Sea surface temperature (SST) is one of the most essential and crucial physical oceanographic parameters and climatologic variables which define and influence regional and global climate regimes. At the interface of ocean and atmosphere, SST modulates the heat fluxes between the ocean and atmosphere, affects the oceanic and atmospheric circulations, properties of the seawater, biochemical processes, primary production, weather patterns and local phenomena such as severe storms, extreme precipitation and heat waves (Deser, Alexander, Xie, & Phillips, 2010; Pisano et al., 2020; Trenberth, 2009).
SST responds to anthropogenic and natural climate changes and variabilities in different time scales (i.e., seasonal, inter-annual, decadal and multi-decadal) (Deser et al., 2010; Pisano et al., 2020; Trenberth, 2009). The solar forcing, wind forcing, cloudiness, ocean-atmosphere interactions, and ocean-atmosphere circulations affect and modulate SST on different time scales (Gastineau & Frankignoul, 2015; Hurrell & Deser, 2009; Pisano et al., 2020; Rencurrel & Rose, 2020). However, in the last 50 years, greenhouse gas emissions caused by anthropogenic processes have changed the heat energy balance of the planet Earth on a global scale. About 90% of this additional heat energy generated by anthropogenic greenhouse gasses is absorbed in the ocean, resulting in a warming of the SST of the world ocean (Core Writing Team, Pachauri, & Meyer, 2015; Pastor, Valiente, & Palau, 2018; Stocker et al., 2013; Trenberth, Fasullo, & Balmaseda, 2014). Therefore, SST is a key and essential parameter for monitoring the ocean’s present state and predicting future climatic events.
Regionally, the Mediterranean Sea responding to climate change by continuous and rapid warming in the last few decades. The Mediterranean Sea warming trend is about twice the global ocean warming trend. Since the pre-industrial era, the annual mean SST of the Mediterranean Sea is increased by about 1.0-1.5 ℃, especially with a higher rate in the last decades, while the highest SST warming was recorded in the Levantine Basin of the Eastern Mediterranean Sea (El-Geziry, 2021; Macias, Garcia-Gorriz, & Stips, 2013; Pastor et al., 2018; Pisano et al., 2020; Samuel-Rhoads et al., 2013). This rapid and continuous SST warming trend of the Levantine Basin (ranging between 0.025–0.055 ℃/year) in the last few decades has been reported in several studies by using different methods (i.e., observational, model, reanalysis, and satellite) (El-Geziry, 2021; Macias et al., 2013; Pastor et al., 2018; Pisano et al., 2020; Samuel-Rhoads et al., 2013; Shaltout & Omstedt, 2014).
Despite their limitations (Jordà et al., 2017; Romanou et al., 2010), the fifth-generation atmospheric reanalysis (ERA5) data sets of the European Centre of the Medium-Range Weather Forecast (ECMWF) reanalysis (Hersbach et al., 2020) data sets are beneficial, powerful tools and widely used for climate analysis, especially due to the temporal and spatial difficulties of in-situ observations.
The SST, along with the salinity, is a fundamental parameter that affects and determines the physical oceanographic characteristics of the water masses in the Levantine Basin. The processes of local water mass formation in the region, i.e., Levantine Surface Water (LSW), Levantine Intermediate Water (LIW) and Levantine Deep Water (LDW), are well studied in the literature (Deliceırmak & Salihoğlu, 2020; Fach et al., 2021; Salihoglu et al., 2019; The LIWEX Group, 2003; The POEM Group, 1992).
This study aimed to evaluate and analyse SST trends in the southern Cilician Basin by observational time-series data sets of the Kyrenia Meteorological Station for 25 years between 1995 and 2020. ERA5 reanalysis and in-situ Conductivity – Temperature – Depth (CTD) measurements are used to compare and validate the data sets.