Ocean systems - halocline

AS 91413

Year 13 SCIENCE

Ocean systems – course topics1. Ocean composition2. Ocean circulation3. The carbon cycle4. Transport matter, energy – heat, tides and waves5. Southern Oscillation – El Nino & La Nina

Ocean systems – course topics

1. Ocean composition – temperature, density, salinity, pressure and gradients

2. Ocean circulation – currents, thermohaline circulations, Coriolis effect

3. The carbon cycle – physical pumps, biological pumps, carbonate and CO2 chemistry

4. Transport matter, energy – heat, tides , waves and Tsunamis

5. Southern Oscillation – El Nino & La Nina

Halocline -arcticThe halocline is a 150m deep band of water starting at 50m depth of steeply rising salinity Three layers:Mixed top layer of

In the plot, one can discern three layers:In the plot, one can discern three layers:In the plot, one can discern three layers:In the plot, one can discern three layers:

The top 50m mixed layer has low salinity < 33 PPT

Originates from inflow of freshwater of melting glaciers and terrestrial rivers in Siberia, Alaska & Canada during summer

The temperature is -1.8 °C, which is very near to the freezing point, chilled by cold air.

This top layer blocks heat transfer from the warmer, water below from the Gulf stream into the ice sheet

This insulation has considerable effect on the thickness of the ice.

Arctic & Antarctic HaloclinesIn high latitudes of the Arctic Ocean, Bering

sea and the Southern Ocean, the surface waters are actually colder than the deep waters.

Here the halocline is responsible for maintaining water column stability- isolating the surface waters from the deep waters. I

n these regions, the halocline is important in allowing for the formation of sea ice

Arctic ice cap at North PoleDark blue areas cold water -1.8 to 1 CPale blue ice melt, floes, ice bergsWhite Sea ice

Arctic ice cap at North PoleDark blue areas cold water -1.8 to 1 CPale blue ice melt, floes, ice bergsWhite Sea ice

Nuclear submarine & polar bears

Ice formation in winterAs ice forms from sea water the salts are left

behind in the water.The ice is freshAs a result the salinity increases , becoming

more dense an falling to greater depths.

SummaryWarm water heated by the sun lies near tropical

and equatorial oceans close to the ocean surface and is less dense

Cold water lies near the poles away from direct sun and is deeper down

Thermocline is the rapid change in temperature with depth which is found in the pycnocline layer.

Large currents move around the world mixing cold water with warm with many effects on climate, and plankton, plants and animals living in the sea.

Cross – section through the ice capBering Strait

Polar Ice cap

Arctic Halocline is 50-200m thick

50-200m