Planetary Radiation Budgets - ceres

Planetary Radiation Budgets
Robert Kandel and Michel Viollier
Laboratoire de Météorologie Dynamique
LMD – IPSL, Ecole Polytechnique
Palaiseau, France
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
1

Radiation Balance : R N =
absorbed SW flux – emitted LW flux
(averaged over the planetary surface)
CERES STM
23-25 Sept. 2003
Energy Balance : R N – P = 0
P = average energy flux from the planetary interior
R. Kandel & M. Viollier
Planetary Radiation Budgets
2

Absorbed SW flux = ¼ ( S 0 /a 2 ) ( 1 – A )
Bond Albedo A =
mean reflected SW flux
mean incident SW flux
(Means over planet’s entire surface)
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
3

Z
q S
q v
f v
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
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Each radiance measured
(e.g. from A or N)
is a single sample of
directions (q S ; q v , f v )
contributing to the fluxes
emerging at those points.
P
A
N
P’
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
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Each radiance measured (e.g. from A or N) is a
single sample of directions (q S ; q v , f v ) contributing to
the fluxes emerging at those points.
The flux measured
with WFOV results
from radiances from
points N, A, P, P’, etc.
each with its set of
angles, each more or
less representative of
the flux emerging at
those points.
P
A
CERES STM
23-25 Sept. 2003
N
P’
R. Kandel & M. Viollier
Planetary Radiation Budgets
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CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
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Replacing the satellite by a much
more remote observer, say on
another planet –
It’s the same problem
Observer
P
A
N
Observed
planet
CERES STM
23-25 Sept. 2003
P’
R. Kandel & M. Viollier
Planetary Radiation Budgets
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CERES STM
23-25 Sept. 2003
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Planetary Radiation Budgets
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CERES STM
23-25 Sept. 2003
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Planetary Radiation Budgets
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VENUS
b V
EARTH
SUN
b M
CERES STM
23-25 Sept. 2003
MARS
R. Kandel & M. Viollier
Planetary Radiation Budgets
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Bond Albedo Estimates Old and New
Allen Chamberlain
PLANET
1955
1979
1999
2002
TCAEP
NSSDC
Mercury
0.060
0.056
0.06
0.06
0.119
0.119
Venus
0.61
0.72
0.72
0.76
0.750
0.750
EARTH
0.34
0.39
0.39
0.40
0.304
0.304
Mars
0.15
0.16
0.16
0.16
0.16
0.250
Jupiter
0.41
0.45
0.70
0.51
0.70
0.343
Saturn
0.42
0.75
0.75
0.50
0.75
0.342
Uranus
0.45
0.90
0.90
0.66
0.90
0.30
Neptune
0.54
0.82
0.82
0.62
0.82
0.29
Pluto
0.16
0.15
0.15
0.50
0.145
0.4-6
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
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PLANET
Mercury
Venus
EARTH
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
Bond Albedo Estimates Old and New
1955
0.060
0.61
0.34
0.150
0.41
0.42
0.45
0.54
0.16
1979
0.056
0.72
0.39
0.16
0.45
0.75
0.90
0.82
0.15
Astronomy
textbook Univ. Website 2003 ?!?
1999
0.06
0.72
0.39
0.16
0.70
0.75
0.90
0.82
0.15
2002
0.06
0.76
0.40
0.16
0.51
0.50
0.66
0.62
0.50
TCAEP
0.119
0.750
0.304
0.16
0.70
0.75
0.90
0.82
0.145
NSSDC
0.119
0.750
0.304
0.250
0.343
0.342
0.30
0.29
0.4-6
?!
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
11

Bond albedo A = p q
both geometric albedo p and phase integral q have changed
geometric albedo p =
planet’s brightness at Sun angle β = 0
brightness of a perfectly diffusing disk of same size
VENUS
b V
EARTH
SUN
b M
phase integral
q
=
2
π
∫
0
[ L( β )/
L(0)
] sin β dβ
MARS
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
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CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
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Bond albedo A = p q
both geometric albedo p and phase integral q have changed
Allen 1955
NSSDC 2003
Planet
p
q
A
p
q
A
Mercury
0.093
0.65
0.060
0.106
1.12
0.119
Venus
0.49
1.24
0.61
0.65
1.15
0.750
EARTH
0.34
1.00
0.34
0.367
0.83
0.306
Mars
0.136
1.10
0.150
0.150
1.67
0.250
Jupiter
0.37
1.11
0.41
0.52
0.66
0.343
Saturn
0.42
1.00
0.42
0.47
0.73
0.342
Uranus
0.41
1.10
0.45
0.51
0.59
0.300
Neptune
0.50
1.08
0.54
0.41
0.71
0.290
Pluto
0.16
1.00
0.16
0.5-
0.7
0.8
0.4-
0.6
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
13

Ground-based Earth albedo ?
Replacing the satellite by an
observer, on the Moon –
It’s still the same problem,
but worse
Moon
P
A
N
P’
Earth
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
6
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
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Bond albedo A = p q
both geometric albedo p and phase integral q have changed
Allen 1955
NSSDC 2003
Planet
p
q
A
p
q
A
Mercury
0.093
0.65
0.060
0.106
1.12
0.119
Venus
0.49
1.24
0.61
0.65
1.15
0.750
EARTH
0.34
1.00
0.34
0.367
0.83
0.306
Mars
0.136
1.10
0.150
0.150
1.67
0.250
Jupiter
0.37
1.11
0.41
0.52
0.66
0.343
Saturn
0.42
1.00
0.42
0.47
0.73
0.342
Uranus
0.41
1.10
0.45
0.51
0.59
0.300
Neptune
0.50
1.08
0.54
0.41
0.71
0.290
Pluto
0.16
1.00
0.16
0.5-
0.7
0.8
0.4-
0.6
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
15

Radiation Balance
R N = absorbed SW flux – emitted LW flux
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
16

Radiation Balance
R N = absorbed SW flux – emitted LW flux
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
17

Earth’s Energy Balance :
342 incident SW flux
102 reflected
SW flux
NOT 137
R N - P = 0
240 LW flux
to space
absorbed SW flux
Energy Balance = 240 : R N - P = 0
P = 0.086
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
618

Jupiter’s Energy Balance :
12.6 incident SW flux
4.3 reflected
SW flux
or 8.8 ?!
R N - P = 0
13.6 LW flux
to space
absorbed SW flux
= 8.3
Energy
or is
Balance
it 3.8 ?!
: R N - P = 0
P = 5.3… or 9.8 ?!
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
719

What we need : Bond albedo, M LW , R N
with error bars and discussion
PLANET
1955
A
1979
1999
2002
TCAEP
NSSDC
Mercury
0.060
0.119 0.056
0.06
0.06
0.119
0.119
Venus
0.61
0.750 0.72
0.72
0.76
0.750
0.750
EARTH
0.34
0.304 0.39
0.39
0.40
0.304
0.304
Mars
0.15
0.250 0.16
0.16
0.16
0.16
0.250
Jupiter
0.41
0.343 0.45
0.70
0.51
0.70
0.343
Saturn
0.42
0.342 0.75
0.75
0.50
0.75
0.342
Uranus
0.45
0.30
0.90
0.90
0.66
0.90
0.30
Neptune
0.54
0.20
0.82
0.82
0.62
0.82
0.29
Pluto
0.16
0.4-0.6 0.15
0.15
0.50
0.145
0.4-6
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
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Error bars also needed
for planetary LW flux (or T e ) and P
And we need to make astronomers better aware of
what we have learned about planet Earth !
not just global annual means,
also the annual cycle of global means,
and much more !
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
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Example : Global mean reflected SW flux
SW GLOBAL MEANS
SW FLUX Wm -2
115
110
105
100
95
90
1 2 3 4 5 6 7 8 9 10 11 12
MONTH
1985
1986
1987
1988
1989
1994
1995
1998
1999
2000
2001
2002
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
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100 x ALBEDO
32
30
28
26
Example ALBEDO : Global GLOBAL mean MEANSalbedo
1 2 3 4 5 6 7 8 9 10 11 12
MONTH
1985
1986
1987
1988
1989
1994
1995
1998
1999
2000
2001
2002
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
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LW FLUX Wm -2
245
240
235
230
225
Example LW : Global GLOBAL mean MEANS LW flux
1 2 3 4 5 6 7 8 9 10 11 12
MONTH
1985
1986
1987
1988
1989
1994
1995
1998
1999
2000
2001
2002
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
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NET GLOBAL MEANS
Example : Global radiation balance
NET FLUX Wm -2
20
15
10
5
0
-5
-10
-15
-20
1 2 3 4 5 6 7 8 9 10 11 12
MONTH
1985
1986
1987
1988
1989
1994
1995
1998
1999
2000
2001
2002
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
25

Some things are settled, others not
We need to make astronomers better
aware of what we have learned about
planet Earth !
CERES STM
23-25 Sept. 2003
R. Kandel & M. Viollier
Planetary Radiation Budgets
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