INTRO TO MARINE SCIENCE - Chapter 7 Reading Notes (UNFINISHED)

Ocean Structure and Circulation

Mixed Layer

a surface layer ten to a few hundred of meters thick

Thermocline

a region extending from the bottom of the mixed layer to a depth of about 1000 m

Isothermal Layer

a layer of constant temperature

Halocline

marked change in salinity with depth

Pycnocline

closely follows the thermocline; extends from the bottom of the mixed layer to a depth of about 1000 m

If the density of the water increases with depth, the water column from the surface to that depth is _________.

stable

If there is higher density water on top of lower density water, the water column is __________.

unstable

Continuity of flow

because water is a fixed quantity in the oceans, it cannot be accumulated at one location or removed at another location without movement of water between those locations

Thermohaline circulation

motion caused by variations in density due to differences in temperature and salinity

Downwelling zones

areas of thermohaline circulation where water sinks

Upwelling zones

areas of rising waters

Convergence

formed when the surface waters are driven together by the wind or against a coast

Divergence

 occurs when the wind blows surface waters away from an area or a coast

Isopycnal

when the water column has the same density over depth, it has neutral stability

Isothermal

water temperature is unchanging over depth

Isohaline

salinity is constant over depth

Caballing

mixture of two water types with the same density – produces new water types with greater density that will sink

What happens at downwelling zones?

Transports oxygen-rich surface water to depth, where it is needed for deep living animals

What happens at upwelling zones?

Returns low-oxygen content water with dissolved, decay produced nutrients to the surface, where the nutrients act as fertilizers to promote photosynthesis and the production of more oxygen in sunlit surface waters

Water at a convergence ___________.

sinks or downwells

Water at a divergence __________________.

upwells from below