Ocean and Climate

• deep water formation


  need to make very dense water helping to drive ocean circulation
• thermocline 


  region of water column with a strong temperature gradient separating surface mixed layer from deeper layers
• to make denser water you can add salt or reduce temperature
• isothermal


  a constant of temperature like isohaline, isopycnal
• homogenous


  properties remain the same throughout
• water column stability 


  the density of the water decreases with depth, then the water column is unstable and gravity forces the water column to stabilise itself in a process called convection
• convection 


  when a water column is unstable, the heavier water will sink displacing the lighter water upwards and producing convective overturning to remove instability
• water mass 


  a body of water identifiable by its characteristic salinity and temperature
• mixing


  if two water masses are mixed together a new water mass will be formed with properties between those of the original water masses
• surface warming increases in temperature and reduction in p
• surface cooling decreases the water and increases the p
• balancing between incoming and outgoing radiation indicates


  warming in summer, cooling in winter and poles
• creating a new density at the surface by cooling is known as convection
• potential temperature


  measure of temperature which takes in account of pressure
• northward heat flux


  north Atlantic warm surface water moving poleward and deep cold water moving southward
• Continuity of volume


  volume of water moving north must equal the volume of water moving south
• water must sink in north and be upwelled in tropics for circulation below
• thermohaline is a convergence belt circulation
• convergence belt circulation

  A) warm surface current

  B) intermediate waters

  C) antarctic circumpolar current

  D) warm and freshen

  
• convergence belt circulation


  surface wind-driven circulation that counters deep water circulation
• dense deep water formed at poles which sink
• depth of sinking water is determined by density of water mass and surrounding water
• circulation dependant on mixing of warm water from above to dilute water at bottom enabling it to be pushed up and replaced
• deep water formation


  increase in density causes water to sink
• cooling causes water to sink
• ice formation rejects salt which increases the density
• evaporation increases the salinity
• near-boundry sinking


  controlled alongshore density changes
• what are the two types of sinking?

  near-boundary and open ocean
• liquid freshwater has a maximum density at 3.98 C
• ice stops convection of heat at surface
• isothermals in freshwater must form at 4 C before cooling any further
• ice will only form at the top of the lake
• freezing point in in saltwater is lowered by increased pressure
• for ice to form in saltwater the water column must be homogeneous and haline stably stratified
• ploynyas


  area of open water surrounded by sea ice
• polynya

  A) open ocean polynya

  B) coastal polynya

  C) sensible heat

  D) winds from continent

  E) new ice pushed away

  F) latent heat

  
• prolonged cooling as waters held in gyres form connective chimneys
• newly formed dense water will have specific temperature and salinity characteristics
• sensible heat polynyas 


  cooling surface causing water to sink before the freezing point then a hole will form at the surface allowing heat to escape