Temperature and salinity in standard sections and northern boundary regions

Photo: Lawrence Hislop, Norwegian Polar Institute.

Abiotic ecosystem components - data from 2019
Typography
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The Fugløya–Bear Island Section covers the inflow of Atlantic and Coastal water masses from the Norwegian Sea to the Barents Sea, while the Kola Section covers the same waters in the southern Barents Sea. Note a difference in the calculation of the temperatures in these sections; in the Fugløya–Bear Island Section the temperature is averaged over the 50–200 m depth layer while in the Kola Section the temperature is averaged from 0 to 200 m depth.

 Since 2015, the temperatures in the inflowing Atlantic Water to the Barents Sea has decreased by more than 1°C (Fig. 3.1.5). At the Fugløya–Bear Island section, which is in the far western entrance, the temperatures of the inflowing Atlantic Water was in 2019 at the same level as in the early 2000s. The decrease in the Atlantic Water temperatures are linked to lower temperatures upstream in the Norwegian Sea. The lower temperatures, in combination with lower inflow during winter (Fig. 3.1.4) has caused the increases in winter sea ice observed the resent years. The decrease in temperatures were lower when progressing into the Barents Sea (at Vardø–North). The salinity of the inflowing Atlantic Water has decreased since 2011 and were in 2019 at the same level as during the very fresh (and cold) period in the late 1970s (Fig. 3.1.5).

Figure 3.1.5. Average temperature (left) and salinity (right) in August–September in the 50–200 m layer in the Fugløya–Bear Island and Vardø–North Sections. Black lines show annual August–September values, while thick coloured lines show three years running means. Horizontal lines show average over the period 1981–2010. Figure 3.1.5. Average temperature (left) and salinity (right) in August–September in the 50–200 m layer in the Fugløya–Bear Island and Vardø–North Sections. Black lines show annual August–September values, while thick coloured lines show three years running means. Horizontal lines show average over the period 1981–2010.

Temperature of coastal and Atlantic waters in the Kola Section in 2019 was typical of warm years in general. During the 2019 observation period, positive temperature anomalies in the 0–200 m layer in coastal waters and Atlantic waters of the central part of the section (Murman Current) were decreasing from 0.9°C in March to 0.2–0.3°C in November–December (Fig. 3.1.6). In Atlantic waters in the outer part of the section (Central branch of the North Cape Current), a temperature anomaly first increased from 0.2°C in March to 0.6°C in June and then decreased to a value close to average in October and to a negative value (−0.2°C) in November; in December, it grew again up to 0.4°C. Compared to 2018, coastal waters had almost the same temperature in March–June 2019, whereas Atlantic waters in March–August 2019 were colder by 0.2–0.5°C in the central part of the section and by 0.3–1.0°C in the outer part (Fig. 3.1.6).
Salinity of coastal and Atlantic waters in the Kola Section in 2019 was lower than average and, in general, close to that in 2018 (Fig. 3.1.6). In coastal waters (0–200 m), a negative salinity anomaly was decreasing from −0.22 in March–May to −0.02 in December. In Atlantic waters in the central part of the section (Murman Current), it was also decreasing from −0.17 in March to −0.05 in December but with a less pronounced trend. In Atlantic waters in the outer part of the section (Central branch of the North Cape Current), a negative salinity anomaly varied slightly from −0.04 to −0.09 during the 2019 observation period. March–December averaged negative salinity anomaly decreased from −0.14 in coastal waters to −0.09 in Atlantic waters of the central part of the section and to −0.06 in Atlantic waters of the outer part (Fig. 3.1.6).

Figure 3.1.6. Monthly and annual temperature and salinity anomalies in the 0–200 m layer in the Kola Section. St. 1–3 – Coastal waters, St. 3–7 – Murman Current, St. 8–10 – Central branch of the North Cape Current (Anon., 2019). Annual mean values for 2016–2019 were recovered.Figure 3.1.6. Monthly and annual temperature and salinity anomalies in the 0–200 m layer in the Kola Section. St. 1–3 – Coastal waters, St. 3–7 – Murman Current, St. 8–10 – Central branch of the North Cape Current (Anon., 2019). Annual mean values for 2016–2019 were recovered.

In the northern Barents Sea (NW) there was a strong temperature decrease from 0.30°C in 2018 to −1.20°C in 2019. No temperature could be calculated for the northeastern Barents Sea due to data coverage.

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