The Barents Sea has become colder since 2015–2016, and the cooling continued from 2018 to 2019. However, the air and water temperatures are still being typical of warm years. In the western entrance of the Barents Sea, the Atlantic Water temperatures in 2019 were at the same level as in the early 2000s. Coastal and Atlantic waters in the Kola Section were fresher than in 2018. In autumn, the area of Atlantic waters (>3°С) decreased slightly and the area of Arctic waters near bottom (<0°С) increased slightly compared to 2018, whereas the area of cold bottom waters (<0°С) almost tripled com-pared to the previous year. Ice coverage has increased since 2016 due to lower temperatures and lower inflow of Atlantic Water. In 2019, the ice coverage was below average but higher than in 2018; its seasonal maximum (51%) was in March, a month earlier than usual, its seasonal minimum (1%) was in September, as usual.
In 2019, the winter (December–March) NAO index was 2.09 that was much higher than in 2018 (0.30). Over the Barents Sea, southerly and southeasterly winds prevailed in January–March 2019, easterly and northeasterly winds – during the rest of the year. The number of days with winds more than 15 m/s was higher than usual most of the year. It was lower than or close to the long-term average (1981–2010) in the western part of the sea in January, April and October, in the central part in January, February, April, August and December, in the eastern part in January, April and December. In June (in the east) and July (in the east and center), the storm activity was a record high since 1981.
The volume flux into the Barents Sea varies with periods of several years. The annual volume flux was relatively high during 2003–2006 (Fig. 3.1.4). From 2006 to 2014, the inflow was relatively stable before it increased substantially in 2015 to about 1 Sv above the long-term average. The year of 2016 had relatively low inflow. Since 2017 the annual volume inflow to the Barents Sea has decreased, but the data series presently stops in May 2019 thus the annual value of 2019 should presently be considered a rough estimate. There is no statistically significant trend in the annual volume fluxes.
Time series of area covered by Arctic Water masses in 50–200 m depth show a strong shift occurring around 2006 (Fig. 3.1.14), with substantially larger extent of Arctic Water before than after. The extent of the Atlantic Water masses show a more gradual increase over the period from 1970 to 2019, and vary to a large extent in synchrony with the temperature of the inflowing Atlantic Water in the western Barents Sea (Fig. 3.1.14).
In December 2018, the Barents Sea ice extent (expressed as a percentage of the total sea area) equalled 15% and was the lowest since 1951. However, in January–March 2019, ice formation accelerated significantly, and in March (a month earlier than usual), the ice-covered area reached a seasonal maximum of 51% and was close to the long-term average (1981–2010) (Fig. 3.1.3).
Sea surface temperature (SST) (http://iridl.ldeo.columbia.edu) averaged over the southwestern (71–74°N, 20–40°E) and southeastern (69–73°N, 42–55°E) Barents Sea dropped significantly in 2019 compared to the previous year and its annual mean value was the lowest since 2011 (Fig. 3.1.7). The SST in the southwestern part of the sea was close to the long-term average (1982–2010) for most of the year; small negative anomalies of −0.2, −0.3 and −0.1°С were found in July, August and November respectively; positive anomalies of more than 0.5°C were only observed in January, February and September.
Mean temperature in the upper, intermediate and deep waters were calculated for polygons for possible inclusion in multivariate analysis (Fig. 3.1.16). The polygons series show that the temperature in the upper, intermediate and deep waters in August–September 2019 were higher than the mean (1981–2010) in most subregions. The exceptions were the outer boundary subregions; the South West and the Franz Victoria Trough, where they were slightly below the mean. At Great Bank, the temperatures at bottom were in 2019 below the mean.