Geoscience Reference
In-Depth Information
1.6
1.4
1.2
1.0
0.8
Figure 22.11
Model-simulated
values of a in Equation (22.27)
given by a 'slab model'
simulation of surface-ABL
coupling with different
prescribed values of surface
resistance initialized using field
data on nine days. Also shown is
the polynomial fit to the average
values of these different curves
described in the text. (Redrawn
from Shuttleworth et al., 2009,
published with permission.)
0.6
0.4
0.2
0.0
10
100
1000
10000
Natural logarithm of surface resistance (in s/m)
was calculated, where
A
is the energy available at the surface. Shuttleworth
et al.
(2009) subsequently re-normalized McNaughton and Spriggs' daytime average
values of
to give the equivalent all-day average values.
Figure 22.11 shows (as thin lines) the original results of the McNaughton and
Spriggs model study for the nine days on which simulations were made and reveals
the substantial day-to-day variability given by the different initiations, much of
this variability being related to differences in the strength of the inversion. The
thick line in Figure 21.10 is a polynomial fit to the average values of
α
α
over these
nine days (Shuttleworth
et al.
, 2009), which has the form:
2
⎡
r
⎤
⎡
r
⎤
⎛⎞
⎛⎞
a
=−
1.26
0.24141 ln
s
−
0.07199 ln
s
⎢
⎜⎟
⎥
⎢
⎜⎟
⎥
MS
&
⎝⎠
70
⎝⎠
70
⎣
⎦
⎣
⎦
(22.31)
3
4
5
⎡
⎛⎞
r
⎤
⎡
⎛⎞
r
⎤
⎡
⎛⎞
r
⎤
+
0.0099 ln
s
+
0.00504
ln
s
−
0.00083 ln
s
⎢
⎥
⎢
⎥
⎢
⎥
⎜⎟
⎜⎟
⎜⎟
⎝⎠
⎝⎠
⎝⎠
70
70
70
⎣
⎦
⎣
⎦
⎣
⎦
Figure 22.12 compares the predictions of Equation (22.31) to experimental
measurements of the relationship between
and daily average surface resistance
made in the semi-arid climate of southern Arizona, over three different land
covers (Shuttleworth
et al.
, 2009). The results suggest that the model relationship
α
