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WP3.1 Radiative closure (EUCAARI)
Radiative closure
• Use in-situ measured (and inferred) aerosol optical properties and radiative transfer code to model fluxes
• Compare with broad band radiometer measurements on aircraft
• To date:– Identification of suitable flights (B362 and B374)– Assessment of accuracy of BBRs and need for
pitch/roll corrections– Preliminary calculations with Edwards and Slingo
(1996)
B362 May 6, 2008
58
56
54
52
50
48
La
titu
de
(d
eg
)
1050-5Longitude (deg)
Flight Track
B362
100
80
60
40
20
0
CN
(cm-310
3)
12:0006/05/2008
12:15 12:30 12:45 13:00 13:15
Time (GMT)
1.0
0.8
0.6
0.4
0.2
SS
A
12
8
4
abs - 550 nm
(m·10
-6)
300
200
100
0 sca
t-55
0 nm
(m
·10
-6)
15x103
10
5
0
Alt
(fee
t)
80
60
40
20
RH
(%)
1000
800
600
400
200
0
CO
(ppm
)
Run 6 - B to A, 10 kft Run 7- B to A, 2.5 kft Run 8 - A to B, 100 ft
B362
B374 – Radiation flight with CMET
58
56
54
52
50
La
titu
de
(de
g)
-10 -5 0Longitude (deg)
Flight Track
May 14, 2008
51.3
51.2
51.1
51.0
50.9
50.8
50.7
Latit
ude
(deg
)
-13.5 -13.0 -12.5 -12.0 -11.5 -11.0Longitude (deg)
B A
τ(dry)=0.21
τ(dry)=0.24
BBR data from B374
1250
1200
1150
1100
1050
1000
Dow
nwel
ling
Rad
iatio
n / c
os(S
ZA
) (
W m
-2))
-13.0 -12.5 -12.0 -11.5Longitude (along 51 N line)
DRE = -17. 5 W m-2
Run 7 at 24,000 ft (390 mb) Run 5 at 6000 ft Run 2 at 2400 ft (930 mb) Runs 3,4 at 100 ft
Modelled clear sky flux (no aerosol)
With aerosol (dry)
Aerosol hygroscopicity during B374
120x10-6
80
40
0
Nep
h G
reen
Sca
tterin
g (5
50 n
m)
10:0014/05/2008
11:00 12:00 13:00 14:00
dat
80
60
40
20
0
RH
(%
) Green Dry Scattering Green Wet Scattering Wet RH Dry RH
1.8
1.6
1.4
1.2
1.0Hyg
rosc
opic
gro
wth
fact
or, f
(RH
)
908070605040Relative Humidity (%)
Wet nephelometer provides f(RH), ϐ/ ϐ0
Need D/D0 for full mie scattering code(Tang 1997 growth not appropriate)
Further work
• Still to do….– Radiative closure with BBRs for aerosol runs
(wet aerosol – properties now available from use of wet neph data)
– Analysis of orbits/SWS/SHIMS data (to be done by Debbie O’Sullivan, Met Office)
– More radiation flights?