Geography, Environment, Sustainability (Jul 2019)
New Possibilities In The Study Of Coastal Upwellings In The Southeastern Baltic Sea With Using Thermistor Chain
Abstract
The article gives an analysis of a unique data of the thermistor chain, which installed on the D-6 oil platform in the coastal zone of the Baltic Sea. In total 10 temperature sensors were installed at different depths with a recording interval of 1 min, the depth at the installation site was 29 m. Based on satellite data, ship measurements and thermistor chain observation the characteristics and dynamics of the sharp decrease in water temperature which registered in the south-eastern Baltic Sea (Gdansk Bay area), during June 5-12, 2016 are analyzed. The temperature decreasing caused by the simultaneous action of at least two factors: wind-driven Ekman upwelling and advection of cold water. Scales of temporal and spatial variability of water temperature in a coastal zone of the south-eastern Baltic Sea near the coast of the Kaliningrad region are described. This event led to the considerable SST (sea sur face temperature) drop by more than 8 °C for two days. The rate of reduction of its temperature during certain upwelling periods can reach 0.3-0.4 ºС per hour, but the maximum warming rate between phases varies from 0.25 to 0.28 ºС per hour. This dramatically changed the conditions of the thermal balance of the sea sur face. The width of the upwelling, as seen in the SST data, was about 25 km. Satellite data were supplemented with data of a thermistor chain and C TD measurements. The high correlation between water temperature variability and changes in wind parameters: when the wind speed has decreased and its direction has changed, the response of the vertical thermal structure has occurred very quickly, sometimes within 1 hour. Thermistor chain data allow to evaluate the vertical temperature distribution and get more detailed analysis of temporal variability and short pulsations of upwelling.
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