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

The title of this map is “Annual 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 annual surface salinity change of Canada’s oceans.

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 annual sea surface salinity generally decreased in the northern Arctic marine ecoregions, Gulf of St Lawrence and most Pacific waters and increased in the Western Arctic, Hudson Bay and through most of the Atlantic marine ecoregions.

Notes: The climate normal is the three-decade average of climatological variables from 1981 to 2010 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).