Environmental Thematic Maps and Graphics:
Winter sea surface salinity departures (2005 to 2017) from the climate normal reference period, by depth class, marine ecoregion

The title of this map is “Winter sea surface salinity departures (2005 to 2017) from the climate normal reference period, by depth class, marine ecoregion.” This map provides a visual representation of the average winter surface salinity change of Canada’s oceans in the winter season.

On the page, there are three maps and two legends to the upper left and right. The first map (top) displays all of Canada, the second map (left) displays the West Coast, and the third map (right) displays the East Coast. On the maps there are small numbers corresponding to marine ecoregions.

The maps show the change in salinity with shades of green, yellow, orange and red. The first legend (left) lists the map labels and corresponding marine ecoregions. On the second legend (right) salinity is measured using the Practical Salinity Scale (PSS). The legend contains eight categories: ≥1 (forest green), 0.5 to < 1 (deep green), 0.1 to < 0.5 (sage green), 0 to < 0.1 (light green), -0.1 to <0 (yellow), -0.5 to < -0.1 (pale orange), -1 to < -0.5 (orange), < -1 (red). The legend contains three boundary categories: fine dashed lines indicate provincial boundaries, fine black lines indicate marine ecoregion boundaries and fine grey lines indicate marine depth classes.

The maps show that, compared to the 1981 to 2010 climate normal reference period, the 2005 to 2017 average winter sea surface salinity generally decreased on the Offshore pacific, northern Arctic marine ecoregions and throughout the Gulf of St. Lawrence, and increased throughout the rest of the East Coast, in the Strait of Georgia, and in most of the Hudson Bay complex. The Southern and Northern Shelves and Western Arctic had areas of both decrease and increase.

Notes: The climate normal is the three-decade average of climatological variables from 1981 to 2010. Winter data are from January to March. Data are reported using the unitless Practical Salinity Scale (PSS), for more information please see http://salinometry.com/pss-78/ . Data for salinity in the Arctic Ocean are sparser than in other regions. In particular, winter salinity data are more scarce and the modelling methods used could result in artificially high salinities for this season in some regions of the Arctic Ocean.

Sources:
Zweng, M. M., et al., 2018. World Ocean Atlas 2018: Volume 2: Salinity. A. Mishonov Technical Ed., NOAA Atlas NESDIS 82, 50 pp., https://www.nodc.noaa.gov/OC5/SELECT/woaselect/woaselect.html (accessed May 31st 2020).