30
STEPHEN GRIFFIES
climate system. Third, developers are commonly under intense time
pressures to "get the model running." These pressures often prompt ad
hoe measures which, unfortunately, tend to stay around far longer than
originally intended.
2.
Kinematics of flow through a surface
In our presentation of ocean model fundamentals, we find it useful to
start with a discussion of fluid kinematics. Kinematics is that area of mechanics concerned with the intrinsic properties of motion, independent
of the dynamical laws governing the motion. In particular, we establish
expressions for the transport of fluid through a specified surface. The
specification of such transport arises in many areas of oceanography and
ocean model design.
There are three surfaces of special interest in this section.
The lower ocean surface which occurs at the time independent
solid earth boundary. This surface is commonly assumed to be
impenetrable to fluid.3 The expression for fluid transport at the
lower surface leads to the solid earth lcinematzc boundary condition.
To formulate budgets for mass, tracer, and momentum in the
ocean, we consider the upper ocean surface to be a time dependent
permeable membrane through which precipitation, evaporation,
ice melt, and river runoff pass. The expression for fluid transport
at the upper surface leads to the upper ocean lcinematzc boundary
condition.
A surface of constant generalized vertical coordinate, s , is of importance when establishing the balances of mass, tracer, and momentum within a layer of fluid whose upper and lower bounds are
determined by surfaces of constant s. Fluid transport through this
surface is said to constitute the dia-surface transport.
2.1
Infinitesimal fluid parcels
Mass conservation for an infinitesimal parcel of fluid means that as it
moves through the fluid, its mass is constant in time
3 ~ h i s
assumption may be broken in some cases. For example, when the lower boundary is
a moving sedimentary layer in a coastal estuary, or when there is seeping ground water. We
do not consider such cases here.
STEPHEN GRIFFIES
climate system. Third, developers are commonly under intense time
pressures to "get the model running." These pressures often prompt ad
hoe measures which, unfortunately, tend to stay around far longer than
originally intended.
2.
Kinematics of flow through a surface
In our presentation of ocean model fundamentals, we find it useful to
start with a discussion of fluid kinematics. Kinematics is that area of mechanics concerned with the intrinsic properties of motion, independent
of the dynamical laws governing the motion. In particular, we establish
expressions for the transport of fluid through a specified surface. The
specification of such transport arises in many areas of oceanography and
ocean model design.
There are three surfaces of special interest in this section.
The lower ocean surface which occurs at the time independent
solid earth boundary. This surface is commonly assumed to be
impenetrable to fluid.3 The expression for fluid transport at the
lower surface leads to the solid earth lcinematzc boundary condition.
To formulate budgets for mass, tracer, and momentum in the
ocean, we consider the upper ocean surface to be a time dependent
permeable membrane through which precipitation, evaporation,
ice melt, and river runoff pass. The expression for fluid transport
at the upper surface leads to the upper ocean lcinematzc boundary
condition.
A surface of constant generalized vertical coordinate, s , is of importance when establishing the balances of mass, tracer, and momentum within a layer of fluid whose upper and lower bounds are
determined by surfaces of constant s. Fluid transport through this
surface is said to constitute the dia-surface transport.
2.1
Infinitesimal fluid parcels
Mass conservation for an infinitesimal parcel of fluid means that as it
moves through the fluid, its mass is constant in time
3 ~ h i s
assumption may be broken in some cases. For example, when the lower boundary is
a moving sedimentary layer in a coastal estuary, or when there is seeping ground water. We
do not consider such cases here.