| Physical
Climatology: Principles
GEOG 5211/4211 - Fall
2003
Professor Konrad Steffen
CIRES Ekeley Building, S264
Tel o: 492 4524
e-mail konrad.steffen@colorado.edu
Field Excursion:
November 9 & 23, 2003
Exercises on the evaluation
of energy and mass fluxes in the surface boundary layer, on instrumentation
for energy flux measurements, and on climates of vegetated surfaces.
1. Describe the instrumentation need for turbulent energy flux measurements
(sensible, latent) based on the gradient method, for radiation balance, and
for ground heat flux.
2. What is the Richardson Number and why do we use a stability function for
the derivation of convective fluxes?
3. In the following two different sets of measurements are given.
a) Calculate the Richardson Number for
both cases.
b) Plot the temperature and wind profile
on semi-logarithmic paper; e.g., log(z) versus T and V.
c) Derive the roughness length for both
data sets (use plot of log(z) versus V)
d) Discuss the two profiles in the context
of the atmospheric stability.
e) Derive the radiation balance and
the albedo from the two date sets.
f) Calculate the sensible and latent
heat flux for both data sets and use the stability function if needed. To
derive the vapor pressure from the measured relative humidity use the following
approximation:
Relative Humidity = 100 (e/es)
vapor density r = 2.17 e / T; e[Pa], T[K]
e = vapor pressure
es = saturation vapor pressure
P = pressure
Table for saturation vapor
pressure: sat_vapor_table.pdf
QH=[-Cak2(du
* dT)/(ln(z2/z1))2] X
Ca : heat capacity of the air = 0.0012 106 J m-3
K-1
QE=[-Lvk2(du *dr)/(ln(z2/z1))2] X
Lv : latent heat of vaporization = 2.52 106 J kg-1
X: factor stable condition = (1-5 Ri)2
X: factor unstable condition = (1-16 Ri)3/4
g) Derive the ground heat flux as residual
of the above calculated energy balance.
h) Calculate the Bowen ratio for both
case studies.
Instruments heights: Level 1= 0.2 m; level 2 = 0.6 m; level 3 = 1.3 m
JD_time
Net R. S(refl) S(in)
V1 V2 V3
T1 T2 T3
H1 H2 H3
P
W/m2 W/m2 W/m2
ms-1 ms-1 ms-1 C
C C %
% %
mb
303.5521 36.35 199.08 273.81
.97 1.43 1.65 -7.7
-8.0 -8.3 76.0 82.6
87.7 835.66
306.8542 -58.67 .00
.00 .88 1.11
1.35 -13.0 -12.2 -11.7 68.9
67.5 65.7 836.26
V: wind speed H: relative humidity P:
pressure
Net R.: net radiation S(refl).: short-wave reflected radiation
S(in): short-wave incoming radiation
The relative
calibration data from the field class can be downloaded : ftp://seaice.colorado.edu/pub/class
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