Upwelling signal (downward facing) pyrgeometer – Campbell Scientific CNR4 Net Radiometer User Manual
Page 45

Appendix A. CNR4 Performance and Measurements under Different Conditions
upwelling signal (downward facing) pyrgeometer
20
30
‐30
‐20
‐10
0
10
0:
00:
00
1:
00:
00
2:
00:
00
3:
00:
00
4:
00:
00
5:
00:
00
6:
00:
00
:00
00
00
7:
00:
00
8:
00:
00
9:
00:
00
10
:00:
00
11
:00:
00
12
:00:
00
13
:00:
00
14
:00:
00
15
:00:
00
16
:00:
00
17
:00:
00
18
:00:
00
19
:00:
00
20
:00:
00
21
:00:
00
22
:00
23
:00:
0:
00:
Pyrgeometer: U‐emf / sensitivity [W/m²]
Temp of instrument [°C]
Upwelling Signal (Downward Facing) Pyrgeometer
FI
rd facing pyrgeometer
ume
at when am ent temperature varies, t
t far i
ared
ation
roug
me, in
t of ambient temperature. The
lting
d val
yrg
and p
ome
sho
mns 4
TABL
hese
cative
res only, they depend
rongly on
r circumstances; the pyr
eter results, of course, change
the sen
tempera
is is in
l
8. Du
the da
he Pt-100 r
ing may
o sola
g, up
degr
ove
bient tem rature. D
e night
or t
atur
be low
the am
pe
e to fa
d radi
oli
e lat
ffects d not influence
nd res
e calcul ions of
T and
und T. Therefore, t
ot take
coun
e ta
colu
might e
to see “0 –50” for all
sitions t
showing “0”; i
lumn 5, th
” values m
reality b
-20 to +2
The r
g sky
emperature
indicated in
lumn 9. Un
cloudy
ition
sky
erature
equal to a
t temperatu . Under clear con
, the s
erature
lower than
mbient tem rature.
The ground temperature, in column 10, is assumed to be equal to the ambient
temperature. In practice, it may be higher during the day, due to solar heating.
values of the sensors using formulas A-1 and A-2
GURE A-3. Clear day for the downwa
It is ass
d th
bi
he ne
nfr
radi
resu
colu
st
remains
measure
to 7 in
othe
hly the sa
ues of the p
E A-1. T
dependen
eometers
are indi
geom
yran
figu
ters are
wn in
with
sor
ture. Th
dicated in co umn
ring
y,
t
am
ead
pe
rise due t
uring th
r heatin
, the sens
to 10
emper
ees ab
e may
er
than
two e
bient tem
o
rature du
the e
r infrare
ult of th
ative co
at
ng. Th
sky
ter
gro
hey are n
n into ac
t in th
ble. In
mn 4,
one
co
xpect
e “0
to
ay in
po
e “
hat are
0”.
n
esultin
t
is
co
der
cond
s, this
temp
temp
is
is
mbien
the a
re
pe
ditions
ky
Ground temperature may be lower than ambient during the night, due to far
infrared radiative cooling. The sky and the ground temperature can be
calculated from the measured
below.
A-3