Hydrostatic Pressure:
p = -rgz
z = depth
g = grav. Acc.
r = density of seawater
PGF per Unit Mass:
1/r x dp/dx = g x tan(q)
The potential temperature of a parcel of fluid at pressure P is
the temperature that the parcel would acquire if adiabatically
brought to a standard reference pressure P0, usually 1000
millibars. Image is potential temperature at 5m depth
(7/1/04)
The stream function can be used to plot streamlines, which represent the trajectories of
particles in a steady flow. Streamlines are perpendicular to equipotential lines. Considering
the particular case of fluid dynamics, the difference between the stream function values at
any two points gives the volumetric flow rate (or volumetric flux) through a line connecting
the two points.
Hysteresis:
The dependence of the state of a system on
the history of its state. Physics the lag in a
variable property of a system with respect
to the effect producing it as this effect
varies
In oceanography, dynamic topography refers to the topography of the sea surface
related to the dynamics of its own flow. In hydrostatic equilibrium, the surface of the
ocean would have no topography, but due the ocean currents, its maximum dynamic
topography is on the order of two meters
Dynamics: The forces and motions that characterize a system
Entrainment is the movement of one fluid by another
Diapycnal: definition.
In the ocean, density always increases with increasing depth. However, surfaces of constant density
(called "isopycnals") are not always level. Wind, the rotation of the Earth, and other processes
cause density surface to slope. For example, a wind blowing along the coast can cause cold water
which is usually deep to rise up to the surface, leading to water that is too cold to swim in, even in
summer. The direction at right angles to the local isopycnal surface is called the “diapycnal” (i.e.,
across-isopycnal) direction. The angle between the diapycnal direction and vertical (i.e., directly out
from the Earth) is always very small, a fraction of a degree at most. However, the difference
between the two coordinates is very important to oceanographers, because the slope of isopycnals
tells us a great deal about how the ocean is moving, and how it can interact with the coast and the
atmosphere.
Stochastic resonance is observed when noise added to a system changes the system's behavior
in some fashion. More technically, SR occurs if the signal-to-noise ratio of a nonlinear system or
device increases for moderate values of noise intensity. It often occurs in bistable . Strictly
speaking, stochastic resonance occurs in bistable systems, when a small periodic (sinusoidal)
force is applied together with a large wide band stochastic force (noise). The system response is
driven by the combination of the two forces that compete/cooperate to make the system switch
between the two stable states.