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large scale (Fach) / large scale 1 (Lektion)
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- isopicnik lines of equal density
- isohaline lines of equal salinity
- thermoline lines of equal tmeperature
- isobars lines of equal pressure
- adiabatic process fluids are compressible = increase temperature when compressed =decrease temperature when brought to surface >no exchange of heat with surrounding
- a) conservative properties b) unconservative properties a) Properties of sea water that can only change thru mixing eg. salinity or pot. temp b) properties that can change thru other influences eg DO, nutrients
- hypsographic curve curve of relation between land height and ocean depth
- a) cyclonic b) anticyclonic Northern hemisphere: cyclonic when wind or current moves anticlockwise anticlonic when moves clockwise southern hemisphere = opposite
- density influenced by Temperature, salinity and pressure
- temperature can change thru a) b) a)heat b) work (eg compression)
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- potential temperature to compare different water masses of different depths water parcel brought up to surface adiabatically > pressure decrease > temp. decrease
- gravitational stability movement of deep water masses determined by density and this by salinity and temperature
- Denisty warum -1000 = mean value of density is 1030g/m3 density usually changes only in the last 2 digits so we take 1000 off > thus sigma t in this case is 30
- seawater equation of state relation between density salinity, temperature and pressure
- hydrostatic equation is the pressure at a certain depth p= g* ρ (density)*z (depth) wenn density constant > linear relation between hydrostatic pressure and depth Δz 1m =Δp 1db
- thermoclines in different latitudes tropen: strong permanent thermocline mid lat: only strong thermocline in summer bc surface heats up really strog arctic : inverted thermocline (becomes slightly warmer in depth)
- vertical structure of the ocean (mixed layer, ""clines, ) surface layer is well mixed due to influence of the wind thus smal variation in temp, dens, and sal. Below comes strong gradient of each parameter Thermocline, halocline and picnocline deeper depth again only small variations upper layer: high temperature, low salinity and low densitiy deeper layer: low temperature, high salinity, density and high number of nutrients
- stability Equation E Ocean is stable when less dense water lies above denser water if instable denser water lies above less dense water and it will sink E = 1/ρ * dρ/dz E>0 =stable
- Stability Equation 2 Important notice cannot take ρ in situ bc temperature and compressability work against each other thus density in situ is different - have to use potential density ρθ (σt) which comes from potential Temperature; parcel lifts = less compressed/ less dense= temperature sinks which leads to more density again parcel sinks = compressed/more dense =temperature rises which leads to less density E = -1/ρ * dρ/dz - g/C2 C2 = sound
- Density gradient Density gradient is a spatial variation in density over an area
- Stratification and stability general the more stratified an ocean, the momre stable and te more energy is needed to move to the surface -> organism will chose less stratified area to rise to surface more stratified ocean have higher gradient in density the more horizontal the picnoclines the more energy is needed to cross for same distances
- Frequency of Brunt‐Väisälä or Frequency of Stratification N freequency of a vertical motion of displaced parcel to return to the equilibrium (oscillation) the higher E (stratification) the higher is N N = √gE
- boyant forces strength in correlation to the stability in an ocean withtighter isopycnals the same displacement causes greatest difference theof density between the particle and the neighbourhood, thus thebuoyant forces are also stronger.
- potential energy (mgh) relation stratification the more stratified the harder it is to mix the layers, the less potential energy is there less stratified oceans have high potential energy as the wind can mix them easier in the surface area. deep oceans are less stratified = easier to mix thermocline = highly stratified = need high kinetic energy from wind to mix it
- salt fingers most distribution of thermodynamical properties thrugh advection but mixing also important molecular diffusion of heat 100x faster than salt; 2 layers of water on top of each other > hot water will lose heat to cooler layer faster than salt > salt fingers
- density of 2 mixed waters - important notice density is higher than each of the 2 water masses density that mixed
- typical periods for oscillation in a stratified ocean eg. 1 min = highly stratified (more surface) 3-5 hours in the deep sea (hardly stratified) neutral stability (constant potential density) = infinite period
- water masses 3 types central waters = 0- 1km intermediate waters =1-2 km deep and bottom waters = > 2km