Study of short-term Variations of the vertical water temperaturestructure based on observed data in the central zones of the YellowSea, June 2021.

Abstract

This study analyzed the vertical distribution data of watertemperature and velocity observed through mooring of multi-layercurrent meter and thermistor strings at the station of the survey inthe central Yellow Sea for about 8 days from June 1 to June 8, 2021.The short-term variations of the vertical structure of watertemperature and the effect of current were investigated. As a resultof the vertical distribution analysis of water temperature, thethermocline layer is thickly developed between about 12 and 43 m indepth, and the water temperature ranges from about 8.79 to 16.03 ℃,with a maximum of 0.91 ℃/m and an average of 0.23 ℃/m. Inaddition, the average water temperature of the water layer below 45m is about 8.23 ° C, and a diurnal variation of about ± 0.05 ° Coccurred repeatedly during the observation period. As a result ofanalyzing the measured multi-layer current data, the direction of thetidal current is northeastward flow at flood tide and southwestwardflow at ebb tide, and a counterclockwise rotational current. In orderto identify the effect of the current field on the temperaturevariation, a correlation analysis was performed, and the change inthe vertical structure of the water temperature showed a highcorrelation with the variations of tidal current, the dominant flow inthe study area. In particular, a high correlation (r ≒ 0.7) was shown inthe water depth below 45m, which is the depth below the stratified(thermocline) layer, and a time shift of about 2.8 hours exists.