ocean circulation and currents II

water density decreases with

heating - solar radiation, condensation

freshwater addition - precipitation, ice melt, river input

what have the most important effect on density

temperature

what is different about the most impactful effect on density at high latitudes

at high latitudes where water is close to freezing point, salinity effects are dominant

difference in seasonal thermocline

summer thermocline is pronounced with shallow surface mixed layer

winter thermocline almost disappears, with deep surface mixed layer

define neutral layering

no density changes with depth

what does stability relate to in density

the vertical density gradient

what does the presence of thermocline/ halocline/ pycnocline indicate

a stable water column

what changes aout density structure in high latitude waters

sometimes unstable layering

define thermohaline circulation

density driven flow of water generated by the differences in salinity or temperature

describe the concept of water masses

water masses are larges bodies of water originating from a common source region and characterised by a distinctive set of properties, including temperature and salinity

what can be said about water masses in the deep ocean

water masses retain their distincitve temperature and salinity values for long periods

typical cause of undulation of the sea surface

wind

define wave crest

highest point of the wave

define wave trough

lowest point of the wave

define wavelength

distance between consecutive crests

define wave period

time separation between consecutive crests

main factors in wind generation

wind velocity, wind duration (fetch), original sea state

how does fetch affect the wave

the longer the fetch, the longer and higher the wave will be

what is the beufort scale used for

used in navigation to describe the severity of the sea state

define a progressive wave

a wave that travels continously in a medium in a state of direction without a change in its amplitude

stokes drift

the name for wave mass transport

define phase speed

speed at which the crests propagate

the 2 kinds of motion in waves

forward motion of the wave - the wave moves forward as perturbation

the orbital motion of the water particles

describe wave life history

transformation of wave properties, wave refraction, collapse as a shore-breaker

define wave diffraction

bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow

where do intertidal waves occur

density discontinuities and propagate below the surface

how do tsunami warning systems work

deep ocean buoys connected acoustically to a tsunami detector