GLOSSARY - Introduction to the Physical and Biological Oceanography of Shelf Seas - page 371

biological pump The export of carbon
associated with biological growth from the
surface ocean into deep water or the seabed
sediments.
buoyancy frequency The natural frequency
of oscillation of a water particle when it is
displaced vertically in the presence of
density stratification and then released.
Sometimes referred to as the Brunt-Vaisala
frequency.
buoyancy inputs Inputs of heat or
freshwater which alter the density of
seawater, thus changing its buoyancy.
cell quota The amount of a nutrient,
normalized by biomass, within a
phytoplankton cell.
cellular respiration

convective chimneys Localised region of
sinking of water whose density has been
increased, for example by surface cooling.
convective overturning Vertical motions
occurring when the water column is
unstable due to density increasing towards
the surface (for instance, caused by surface
cooling). It can lead to very rapid vertical
mixing.
convectively unstable Condition in which
heavier fluid overlies lighter with the
potential to drive overturning motions.
Coriolis force The apparent force which
must be included in Newton's laws of
motion to describe the movements of a
particle in a rotating system. The Coriolis
force is a key control on large-scale
motions in the ocean and atmosphere.
(See also geostrophic flow.)
Coriolis parameter

Metabolic reactions
within a cell that use some of the fixed
organic compounds to maintain the cell
structures and to synthesise ATP. In the
ocean, respiration typically consumes
oxygen (aerobic respiration), with CO 2
being released back into the water as a
waste product.
coastal currents Flow parallel to a coastline
often driven by density gradients arising
from freshwater inputs from land.
compensation depth The depth, within the
exponentially decaying light profile, at
which a phytoplankton cell would need to
be held in order that carbon fixation by
photosynthesis is just able to balance the
energy requirements of cell respiration. Net
production by the cell would then be zero.
compensation light intensity The intensity of
light (PAR) at the compensation depth.
continental shelf pump

Coriolis force for a
particle mass m moving at speed v has a
magnitude mfvwhere f is the Coriolis
parameter f ¼ 2 O sin f L where O is the
angular speed of the Earth's rotation and
f L is latitude.
critical depth If moved continuously by
mixing through the exponential light
profile between the sea surface and the
critical depth, a phytoplankton cell is
just able to balance its cell respiration
energy requirements with the energy
gained from photosynthesis. Net
production is just zero. The critical depth
is analogous to the compensation depth,
but takes into account vertical turbulent
mixing in the surface layer; the critical
depth is always greater than the
compensation depth.
critical mixing

The export of carbon
from the continental shelves into the
adjacent deep ocean.
continuity

In a mixed water column or a
surface mixed layer, where the water depth
or layer thickness is greater than the critical
depth, net phytoplankton production can
still be possible. If the rate of vertical
mixing is low enough, then the time spent
above the critical depth may allow the
phytoplankton to generate additional
biomass.

Conservation principle, which
requires that what flows into a defined
volume in a defined time, minus what flows
out of that volume in the same time, must
accumulate in that volume. Continuity is
an important constraint on fluid flows
which can be expressed in a variety of
mathematical statements.