Variability of Wind-Driven Coastal Upwelling in the North-Eastern Black Sea in 1979-2016 According to NCEP/CFSR Data

This paper presents the variability of wind-driven upwelling based on results of the coastal upwelling criterion analysis for the Gelendzhik region of the Black Sea for 1979-2016years. The calculations of the criterion are based on the wind data from reanalysis of NCEP-CFSR. The proposed method is used for the analysis of long-term upwelling variability in the Black Sea for the first time. This method allows detecting both full and incomplete upwelling in contrast to measurements of the sea-surface temperature (SST) on regular coastal weather stations or on satellites. Current study shows more than 100 cases of the upwelling (when upwelling criterion<-1) for 37years in total, and some of them were confirmed with a satellite images. Comparison of the SST from Gelendzhik meteostation and upwelling criterion revealed that 70% of the upwelling cases are related to decrease of the temperature on sea surface. It is shown that the highest probability of wind upwelling events is detected in the mid-summer period. Interannual variability of the coastal upwelling criterion is very high, there was 1 year (2010) when no upwelling cases were registered, and maximum 8 cases are registered for 1987year. There are three cases of upwelling on average per year. The process of the coastal upwelling depends on wind impact, but also on direction and strength of the coastal current. Study of the upwelling and its variability is necessary to supplement knowledge about coastal dynamic processes that affect the ecosystem and the recreational potential of the region.