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

The title of this map is “Summer 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 summer surface salinity change of Canada’s oceans in the summer 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 gridded 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 summer sea surface salinity generally decreased in the Strait of Georgia, Southern Shelf, northern Arctic marine ecoregions, and deeper waters on the East Coast, and increased in the Western Arctic, Hudson Bay, Northern Shelf, Offshore Pacific and shallower areas on the East Coast. Salinity decreased the most in the Strait of Georgia.

Notes: The climate normal is the three-decade average of climatological variables from 1981 to 2010. Summer data are from July to September. 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.

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).