There are several words that have been given a specific meaning in this manual. The knowledge of these words is useful for the complete understanding of the following text.
Auxiliary Variable
A variable that represents any
variation during a simulation. The variable is normally a function of either
flow or state variables. Not strictly coupled to the mass/energy balance.
Driving Variables
A forcing variable used as input to
the model. Normally boundary conditions to the equations in the dynamic
model.
Dynamic
A variation that is normally simulated and
because of this follows a flexible type of variation by time.
Empirical
Knowledge found by experience, based on
observations.
Flow
A general term used to describe a movement from one
place to another, most often used for water. Apart from that the term is used
almost synonymous to transfer.
Flow Variables
The Flux of energy or matter. The flow
variables connect state variables or represent source/sink terms to the state
variables.
Flux
The measure of the flow of some quantity per unit
area per unit time, such as joule per square meter and day (heat
flux).
Ground
Radiation processes including both soil and
snow.
Parameter
A single input constant to the model.
Parameter Table
A table that includes one or more
parameters that have a common index.
Rate
A quantity that is measured in relation to unit of
time, such as meters per second (wind speed).
State Variables
A variable that represent the storage of
matter or energy. The mass balance should be conservative for state
variables.
Switch
A switch is a tool used to define how the model
is defined for a given simulation. Switches are changed in the edit menu and
recognized as options.
Transfer
A general term used to describe a movement from
one place to another, used almost synonymous to flow.
Viewing functions
A function that may be visualised at
time of editing values of involved parameter values
In the descriptions of nitrogen and carbon processes, the following conventions for denotations have been used:
(1) Pools (state variables) are denoted by capital italics subscripted with name abbreviations.
(2) Flows are denoted by capital italics subscripted with the direction of the transfer. Layer is indicated by “z” in parentheses.
(3) Parameters are indicated by lower-case italic letters with appropriate subscripts.
These conventions are over ruled when older and commonly used denotations already exist.
The nitrogen carbon ratio in different state pools is an exception to these conventions. When the ratio is a state variable it is denoted by two letters, CN, subscripted with appropriate name abbreviations, and when it is given as a parameter it is also written with these two letters in lower-case italic, cn, with appropriate subscripts.