Kipp & Zonen LAS, Instruction Manual

Page: 6 / 75

5
LIST OF SYMBOLS
SYMBOLS
C
n
2
structure parameter of the refractive index of air [m
-2/3
] (
( )
12 2
2
10
− =
CN
U
n
C
)
C
T
2
structure parameter of temperature [K
2
m
-2/3
]
C
Q
2
structure parameter of humidity [kg
2
m
-6
m
-2/3
]
d zero-displacement height [m]
D aperture diameter of receiver and transmitter unit [m]
f
T
universal stability function [-]
g gravitational acceleration [
∼
9.81 m s
-2
]
G
s
soil heat flux [W m
-2
]
G
1
, HFP
1
soil heat flux plate 1 [W m
-2
]
G
2
, HFP
2
soil heat flux plate 2 [W m
-2
]
H sensible heat flux [W m
-2
]
L path length [m]
L
v
latent heat of vaporization [~2.45
×
10
6
J kg
-1
@ 20
o
C]
L
v
E latent heat flux (or evaporation ET) [W m
-2
] [mm day
-1
]
(conversion [W m
-2
]
↔
[mm day
-1
]: 1 W m
-2
= L
v
/86400
≅
0.0353 mm day
-1
)
L
MO
Obukhov length [m]
Pot potentiometer path length setting at Path length knob [-]
P air pressure [Pa]
Press air pressure [hPa]
(conversion [Pa]
↔
[hPa]: 1 hPa = 100 Pa = 1 mbar)
PU
CN2
scaled C
n
2
[m
-2/3
] ( C
n
2
= PU
CN2
⋅
10
-15
)
Q absolute humidity [kg m
-3
]
Q* net radiation [W m
-2
]
R
d
specific gas constant for dry air [
∼
287 J K
-1
kg
-1
]
RH relative humidity [%]
R
n
net radiation [W m
-2
]
R
v
specific gas constant for water vapour [
∼
461.5 J K
-1
kg
-1
]
T absolute air temperature [K]
T + air temperature upper level [
o
C]
T - air temperature lower level [
o
C][
(conversion K [Kelvin]
↔
o
C [Celsius]:
×
o
C =
×
+ 273.15 K)
T
*
temperature scale [K]
u wind speed [m s
-1
]
u
*
friction velocity [m s
-1
]
U
CN2
log C
n
2
signal [V] (
( )
12 2
2
10
−
=
CN
U
n
C
) [-5 V to 0 V]
U
DEMOD
demodulated signal [V] ( U
DEMOD
= I ) [-1 V to 0 V]
WD wind direction [
o
]
z
LAS
(effective) height LAS or XLAS [m]
z
0
aerodynamic roughness length [m]
z
u
height wind speed measurements [m]