Dataset includes measurements of conductivity (mS cm-1), temperature (°C), sound speed (m s-1) and salinity (PSU) made with the probe Falmouth Scientific Inc. The research was carried out in 2001 (at the turn of May and June), 2003 (beginning of May), 2005 (end of April) and in 2002 and 2004 (at the turn of September and October). In 2002, only temperature and salinity measurements of surface water were carried out (2-hour cycles). In the remaining periods, the measurements concerned a full set of parameters conducted in a vertical profile with high resolution (2- and 4-hour cycles).
The highest surface water temperatures were recorded in autumn (15.0 oC in 2002 and 15.2 oC in 2004, average). In the autumn of 2004, stable thermal stratification occurred. At a depth of 40-50 m formed thermocline with a very large temperature gradient (1,2 oC m-1, average). Above the thermocline was a layer of mixed warm waters ( 15,0 – 15,2 oC temperature range), and below the isothermal layer of minimum temperatures (4 oC, average). Less stable thermal conditions were recorded in the spring of 2001. Primary thermocline was present at a depth of 18-45 m and only the first and last day of the study clearly separated the warmer (9,6 oC and 10.8 oC) mixed surface waters from the colder, isothermal intermediate waters. Temperature gradients in the thermocline ranged from 0,08 oC m-1 to 0,36 oC m-1. The temperature increase during the day made at a depth of 4-9 m secondary thermocline (0,28 oC m-1, max. gradient). However, it was not permanent and subjected to easy erosion by wind mixing. In May 2003 and April 2005 no occurrence of formed thermocline was recorded. The vertical profile marked by a gradual decrease in temperature from the surface layer to the upper limit of the isothermal layer minimum temperatures. The lowest temperatures in the isothermal layer of minimum temperatures were recorded in April 2005 (1.8 oC) and in May 2003 (2.2 oC). In spring 2001 and autumn 2004, the lowest temperatures in this layer were 3.7 and 3.0oC, respectively.
The salinity of surface waters of the Gdańsk Deep ranged from 6.9 to 7.3 PSU. The pycnocline associated with a sharp increase in salinity enveloped usually below a depth of 70 m. In May 2003, the inflow of bottom waters with greater salinity (up to 13.2 PSU) caused the deep layer uplift and the halocline to be raised, the upper limit of which reached 60 m. The most intensive increase in salinity in the halocline was recorded in April 2005. Then the average salinity gradient was 0.25 PSU m-1. The lowest values of salinity gradients were recorded at the turn of May and June 2001. Salinity of bottom waters was in the range from 10.5 to 13.2 PSU.
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- Earth and related environmental sciences (Natural sciences)
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- 10.34808/r23w-v127 open in new tab
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- Gdańsk University of Technology
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