Stratification and Stability Flashcards
What condition indicates a stable stratification in the ocean?
Lighter (less dense) water lies above heavier (denser) water.
What is the stability parameter 𝐸, and what do its values indicate?
E>0: Stability
E=0: Neutral stability
E<0: Instability
What does the Brunt-Väisälä frequency (𝑁) measure?
The frequency of vertical oscillations of a water parcel displaced from equilibrium.
How is the Brunt-Väisälä period related to stability?
Higher stability results in a shorter Brunt-Väisälä period.
Why is potential density (ρ θ) used to assess stability instead of in situ density?
Potential density excludes the effects of pressure, focusing on temperature and salinity changes.
What happens to a water parcel displaced upwards in a stable stratification?
It becomes denser than the surrounding water and sinks back to equilibrium.
How does stratification affect vertical and horizontal mixing?
Stratification impedes vertical mixing but allows easier horizontal mixing along isopycnals.
What is better for larvae, high or low stability?
Lower stability takes less energy to overcome and therefore is better for larvae
Is highly stratified water more or less stable than less stratified water?
highly stratified water is more stable than less stratified water
what is stratification?
refers to layers of water masses in the ocean based on density differences primarily influenced by temperature and salinity.
What is stability in oceanography?
refers to the densityStability in oceanography refers to the resistance of the water column to vertical mixing. It describes how likely or unlikely it is for different layers of water to mix, based on their respective densities.
Very stable water columns are more difficult to mix
what are the densities of the water layers in stable vs unstable conditions?
stable = less dense water is over more dense water
unstable= more dense water is over less dense water
What is double diffusion, and when does it occur?
It occurs when warmer, saltier water overlays cooler, fresher water, leading to salt fingers.
this occurs because the molecular diffusion of heat is 100x faster than that of salt
What information can a T-S (Temperature-Salinity) diagram provide?
The more perpendicular the water column’s T-S profile crosses the isopycnals, the greater the stability. If the profile is more parallel to isopycnals, the water column is less stable
In a T-S diagram, isopycnals are lines of constant density. These lines help you identify water masses and their density based on their temperature and salinity values.
Are more vertical isopyncals more or less stable than more horizontal ones? Which is more preferable for biological resources
more vertical isopyncals are less stable than more horizontal ones, making them preferable for biological resources.
