Metik-Diyunova V.V, Mayboroda S.A.
Black Sea Hydrophysical Proving Ground of Russian Academy of Sciences, Russian Federation, Katsiveli , Shuleykin St., 9.
In this paper a study is performed of the seasonal and interannual variability of the surface temperature of the Black Sea in the area of land-sea coupling zone of Crimean Peninsula and the Northern part of the Black Sea at Cape Kikineiz of South Coast of Crimea (SCC) for the period from 1931 to 2016.
The aim of this work is the analysis of long-term trends of variability of sea surface temperature (SST), the comparison of the obtained results with the data of reanalysis in the respective time intervals, the identification of extreme maximum and minimum values of SST.
In the time course of SST the positive linear trends are highlighted. The angular coefficients are 0,0199, 0,0122, 0,0115 for maximum, average and minimum values, respectively. Interannual fluctuations of these series are in-phase. Comparison of the linear trends of variability of the SST with the results of reanalysis showed the following. For the period 1993–2012 the positive trend of sea surface temperature of Cape Kikeneiz is 0,102 °C/year (exceeding the reanalysis value by 0,035 °C/year). For the period 1985–2006 it is 0,07 ºC/year (exceeding the reanalysis value by 0,01 °C/year). More intensive growth of SST in the SCC area is due to regional characteristics, as well as a different data averaging by the thickness of the surface layer.
The use of polynomial trend revealed the following features in the time course of the SST. The increase in temperature was observed from 1930th to the mid 1950s. Later on, a slow decrease in temperature started until the end of 1980s, with minimums of average values for the entire observation period: 1985 to 13.0°C, in 1993 12,9°C. Since the mid 1990s, the temperature again started to rise. The maximum value of the average annual sea temperature 16,5°C was observed in 2010. Seasonal polynomial trends have differences in the amplitude-phase characteristics. Characteristic for linear trends are: the warm period (April-September) has the largest increase rate 0,02 °C/year, whereas during the cold period this value is 2 times less (0,01 ºC/year).
The annual course of long-term SST and air temperature above it shows a gradual increase in values from February to August. The lowest average SST 7,6°C is observed in February-March, and highest in August (24,1°C). The maximum daily average temperature for the entire observation period 29,5 °C was recorded on August 13, 2010. The extreme minimum SST near Cape Kikineiz (4,4 °C) was observed in February 1976. Standard deviations of daily average SST values range from 0,8°C in February-March to 4,4 °C in June-July.
The study shows high correlation between long-term series of SST and air temperature. A general SST increase in the SCC region is revealed for the period from 1931 to 2016.
Keywords: Black Sea, sea surface temperature, interannual variability, temperature trend, atmospheric forcing
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