Geoscience Reference
In-Depth Information
10.12 Explain physically why turbulent pressure fluctuations are difficult
to
measure reliably.
10.13 Explain in your own terms the physical argument for the sensitivity of
surface-layer
u
and
v
fluctuations to ABL depth but the insensitivity of
w
fluctuations.
10.14 Discuss the physical meaning and implications of the rel
ativ
e uni
mpo
rtance
of turbulent transport in the surface-layer budgets of
uw
and
wθ
in the
unstable surface layer, despite the high turbulence level there.
10.15 Explain why the largest eddies are the most sensitive to buoyancy.
Problems
10.1 Explain why the mean wind and stress profiles in
Figure 10.1
are consistent
with
Eqs. (10.1)
and
(10.2)
.
10.2 Discuss whether the following are M-O similar:
(a) the dissipation rate
,
(b) the Kolmogorov microscale
η
,
(c) horizontal velocity fluctuations,
(d) the drag coefficient
C
d
.
10.3 Derive an expression like
Eq. (10.21)
but for the surface temperature flux.
10.4 Explain how measurements of the mean temperature difference
and
mean wind speed difference
U
between two heights in the surface layer
can be used to infer the surface temperature and momentum fluxes.
10.5 Does M-O similarity hold in a bar
oclinic boundary lay
er? Discuss.
10.6 The temperature structure function
2
is observed to behave
[
θ(
x
)
−
θ(
x
+
r
)
]
as
C
T
2
r
2
/
3
for separations
η
r
z
.Is
C
T
2
M-O similar? If so, write an
M-O similarity expression for it.
10.7 Under the M-O hypothesis the near-surface regions of convective and sta-
ble boundary layers have the same statistical structure. Is this physically
reasonable? Discuss.
10.8 In a convective boundary layer capped by an inversion having drier air,
humidity fluctuations can be generated by the entrainment process at the
ABL top. Could this impact the M-O similarity of humidity fluctuations?
Discuss.
10.9 Discuss the role of the intercomponent-transfer terms in the
u
,
v
,and
w
kinetic energy equations under neutral conditions. What is their magnitude?
Try to interp
ret
them physically with sketches.
10.10 Explain why
uθ
is nonzero in the surface layer. What is its productionmecha-
nism?Howdoes it behave in free convection?Why arewe generally oblivious
to it?
