Download Deep Ocean Currents

Deep Ocean Currents
90% of the ocean’s water!
Depend on
• Density which is affected by
– temperature
• Colder water is more dense
– salinity (how much salt is in the water)
• Saltier water is more dense
Thermohaline circulation
• Refers to deep currents driven by
differences in water temperature and
salinity that arise from
– 1. heating/cooling at the sea surface
– 2. Adding or losing surface freshwater
(evaporation and sea ice formation
increase salinity; precipitation, runoff and
ice-melt decrease salinity)
How does thermohaline circulation
work?
• Transports huge volumes of cold, salty
water from the North Atlantic to the
Northern Pacific and brings warmer,
fresher water in return.
Thermohaline circulation :Called
the “Great Ocean Conveyer”
Oceans and the atmosphere
interact to affect climate
The ITCZ: The Inter-tropical
Convergence Zone
Evaporation,Precipitation
and Oceans
• Trade winds carry evaporated water vapor
to the Inter-Tropical Convergence Zone
where it condenses as rain.
What happens at the ITC Zone?
Intense equatorial sun + warm ocean =
heat + humidity
As this air rises, it cools, and the water
comes down in frequent thunderstorms
Coastal Climates and Oceans
• 1. Lands that get sideswiped by warm
currents tend to have a lot of rain in
addition to a fairly warm climate.
• 2. Lands hit by cold currents tend to
receive very little precipitation in addition
to a comparatively cool climate.
Coastal climates and oceans
• 3. Water warms up and cools off much
more slowly than land or air.
• 4. So coastal areas are insulated by
nearby water and experience narrower
temperature ranges.
• 5. These Temperate climates have
narrower temperature ranges and no
extremes of precipitation.
EX: Maritime Temperate Climate
Zone: Britain
*Has cool summers and mild winters, smaller
annual temperature range.
*Strongly influenced by the ocean, which
maintains fairly steady temperatures across
the seasons.
Ocean as CO2 sink
• Oceans are the largest active carbon sink
on Earth.
• Increased CO2 from human activities is
warming the oceans causing ocean
acidification and less mixing of nutrients
• Major ocean currents could be affected