49
X1
energy: (T2,n TÂ¡>n) = Rnn + hj-,n(Tan Ti>n)
(2-67)
n (*2,n *l,n) (Pv2,n *>vl,n) (T2,n + Tl,n)
+ />wlcpwlDLl va *vl,n) = 0 i2'69)
where:
Rnn
P
^mn
tyin
T
an
^van
net solar radiation incident upon the soil surface
at time step n [W*m'2]
precipitation at time step n [m3*m'3*s"l]
boundary layer mass transfer coefficient at time
step n [nrs"1]
boundary layer heat transfer coefficient at time
step n [W*m"2,0K_1]
air temperature at time step n [1C]
ambient water vapor concentration at time step n
[kg*m'3]
The boundary conditions at the lower boundary of the soil are
developed in a similar manner. The last node has volume and
capacitance for storage of energy and mass. A zero flux boundary
condition is used. There are two ways in which the zero-flux condition
can be represented. These will be developed for the water for the
purpose of illustration.