Campbell Scientific CNR4 Net Radiometer - 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