Salinity Total amount of solid material dissolved in water

1. Salinity • Total amount of solid material dissolved in water • Salinity expressed as parts per thousand (0/00) • Average salinity of saltwater is 3.5% • Most is sodium chloride, common table salt • Sources of Sea Salt • Chemical weathering of rock is one source • Dissolved minerals reach the ocean through runoff from rivers and streams • About 2.3 billion metric tons per year • Earth’s interior is second major source • Water vapor from volcanoes filled the ocean • Many elements were brought to the ocean in this water vapor

2. 3) Processes Affecting Salinity • Salinity is relatively constant throughout the ocean • Salinity ranges from 3.3% to 3.8% • Precipitation, runoff, and melting ice add water to the ocean and lower • the salinity • d) Evaporation and freezing remove fresh water from the ocean and • increase salinity • 4) Temperature Variations • The ocean’s temperature varies with amount of solar radiation • Solar radiation varies with latitude

3. 5) Temperature variation with depth • Temperature profiles change as latitudes change • High latitudes have very little change from top to bottom • Low latitudes have little change from surface to 300m • 300m to 1000m (thermocline) is a steady decrease in temperature • >1000m the temperature levels off at its coldest temperature • 6) Ocean density variations • Density = mass per unit volume • Density changes the vertical position of seawater • Low density water rises • High density water sinks

4. 7) Factors affecting seawater density • Density influenced by salinity and temperature • Temperature has the greatest effect on density • Warm water = low density • Cold water = high density • Density increases as salinity increases • 8) Density Variation with depth • High latitudes have very little change in density from surface to bottom • Low latitudes, changes in density are opposite the change in • temperature (temp down, density up) through the pycnocline • c) Pycnoclineacts as barrier between high density and low density

5. 9 ) Ocean Layering • The ocean is layered according to density • Three layers based on density- surface zone, transition zone and deep zone • 10) Surface zone • Surface gets the most solar radiation • Surface water is mixed by wind and waves • Steady temperature and density profile down to about 300m • 11) Transition zone • 300m to 1000m in depth • Rapid decrease of temperature with depth • Rapid increase of density with depth

6. 12) Deep zone • Below transition zone, no sunlight reaches this zone • Temperature and density stay constant in this zone • Contains about 80% of the water in the ocean • 13) Surface Circulation • Ocean currents-masses of ocean water that flow from one place • to another • b)Surface currents- water that flows horizontally in the upper part • of the ocean’s surface • c) Develop due to friction between the ocean and the wind • d) Can be a seasonal current or a long term general circulation • pattern

7. 14) Gyres • Large whirls of water within an ocean basin • Five main ocean gyres: North Pacific, South Pacific, North Atlantic, South Atlantic and the Indian Ocean • c) The Coriolis Effect influences the movement pattern of the currents • d) Northern Gyres flow clockwise • e) Southern gyres flow counter-clockwise • 15) Ocean currents and climate • Warm water currents help to move heat to cooler areas • Cold water currents help to moderate the temperature of warmer areas • Ocean water movement accounts for about 25% of the heat transfer in • the Earth’s system

8. 16) Upwelling • Rising of cold water from deeper layers to replace warmer surface water • Wind, combined with the Coriolis Effect move warm surface water allowing cold water to come up from deeper layers • Brings greater concentrations of nutrients to the surface • 17) Density currents • Vertical currents of ocean water that result from density differences among water masses • Denser water sinks, less dense water rises • Density changes due to temperature and salinity variations

9. 18) High Latitudes • Most deep-ocean density currents start at latitude • Decreased temp, increased salinity cause an increase in density and a sinking of water • Water then works its way towards the equator • Warmer surface water takes the place of the cold dense water • 19) Evaporation • Density is increased by the removal of the fresh water thru evaporation • Increased salinity causes the water to sink

10. 20) Conveyor Belt • Ocean water travels from the Atlantic to the Indian to the Pacific and then back • Surface water near the equator is warmed and moves towards the poles • Cools at the poles and sinks and moves back towards the equator and is upwelled