木星成層圏と火星古気候
の放射計算

黒田 剛史
NICT/東北大学

木星成層圏の放射計算

Atmosphere of Jupiter• Thermosphere(<10-3hPa)

Vertical structure:observed by Galileo Probe• Stratosphere(102～10-3hPa)• Troposphere(104-5～102hPa)- With cloud layers- Driven by theinternal heat source.

QQO!
[Cosentino et al., 2017][Seiff et al., 1998]

Here we focus on the stratosphere.

Radiative band model CH : Absorber of theCoordinate
solar radiation
4

Band

IR(infrared)/SO(solar)

Wavenumber
range [cm-1]

Molecules

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17

IR
IR
IR
IR
IR
IR
IR, SO
IR, SO
IR, SO
IR, SO
SO
SO
SO
SO
SO
SO
SO

10-200200-400
400-600
600-700
700-860
860-960
960-1200
1200-1400
1400-1700
1700-2100
2100-3450
3450-4800
4800-6300
6300-7800
7800-9200
9300-10800
10800-11800

CH4, H2-H2, H2-He
CH4, H2-H2, H2-He
CH4, H2-H2, H2-He
CH4, C2H2, H2-H2, H2-He
C2H2, C2H6, H2-H2, H2-He
CH4, C2H6, H2-H2, H2-He
CH4, H2-H2, H2-He
CH4, H2-H2, H2-He
CH4, H2-H2, H2-He
CH4, H2-H2, H2-He
CH4, H2-H2
CH4, H2-H2
CH4, H2-H2
CH4, H2-H2
CH4, H2-H2
CH4, H2-H2
CH4, H2-H2

CH4, C2H2, C2H6, collision-induced
transitions of H2-H2 and H2-He:
Effective in the infrared cooling• Correlated kdistribution approach• We made a table of kdistributions in 13
pressure grids (logequal interval between
10-3 and 103 hPa), 3
temperature grids (100,150 and 200 K) for 17
wavenumber bands.
• The atmospheric composition of molecules (1000 ppmv of CH4,
1 ppmv of C2H2, 10 ppmv of C2H6, 86.4 % of H2, 13.6 % of He) isfixed in making the table.

Radiative band model
Molecules(infrared)

Collisioninduced
transitions(infrared)

For solar
absorption

Line spectra(1 hPa, 150K)• Infrared molecular lines (CH4 101800 cm-1, C2H2 600-860 cm-1, C2H6
700-960 cm-1): From HITRAN2008[Rothman et al., 2009]• CH4 lines in 1800-9200 cm-1: Fromhigher-resolution profile by
Sromovsky et al. [2012]• Visible CH4 lines: From Fink et al.
[1977] and O’Brien and Cao [2002]• Voigt profile is used for the
calculation of line spectrum, withwing cutoff of 35 cm-1 for all
molecules.
• Collision-induced transitions of H2H2 and H2-He: From Borysow [2002](H2-H2) and Borysow et al. [1988](H2-He).

Radiative band modelCH4 line spectra (3450-4800 cm-1)

About k-distribution[e.g. Liou, 2002]

k-distribution of the line spectra• For fast calculations of fluxes, the line spectrum in each band isordered to be a monotone increasing function.
• The absorption and emission by molecules in each band are
calculated with 12 k-distribution integration points per a molecule(144 points in the bands the lines of 2 molecules are overlapped).
• The effects of collision-induced transitions are added.

1-D calculation

Setting

1-D calculation with equally-spaced 60 layers between 10-3
and 103 hPa has been performed.
Temperature

Component• Temperature:‘Mean state’ from
Galileo Probeobservation[Yelle et al., 2001]• Component:
From 1-D
photochemical
model [Moses etal., 2005]
2 kinds of results(Models A and C)

1-D calculation(Solid: Band, Dashed: Line-by-line)

Heating/cooling rates• Calculation of solar radiation:
Assumed zenith angle of 0°• Differences between band andline-by-line calculations are verysmall.
• Mid- and far-infrared radiation(10-960 cm-1): Dominant forcooling below ~2.5×10-3 hPa.
• CH4 infrared radiation (9602000 cm-1): Can be dominant forcooling above ~2.5×10-3 hPa,and very small effects below.
• Heating/cooling rates in upper
stratosphere strongly dependon the composition.

1-D calculation(Solid: Band, Dashed: Line-by-line)‘Model A’
component‘Model C’
component

Sensitivity of molecules(infrared cooling)
About the effect of cooling in
10-2100 cm-1:• C2H2 is dominant above~0.03 hPa (up to ~3 K/day).
• C2H6 is dominant between
0.03-10 hPa (up to ~0.2
K/day in this height region).
• Collision-induced transitions
are dominant below ~10hPa (up tp ~0.03 K/day).
• CH4 can be dominantaround the boundary tothermosphere, but its effectis small in most of thestratosphere.

1-D calculation

Total heating/cooling rate
(in comparison with a preceding study)

Total day-mean heating&cooling rates
in comparison with Yelle et al. (2001)[Yelle et al., 2001]• Our calculations of day-mean net
heating and cooling rates are in agood agreement with the results ofYelle et al. (2001), with radiativeequilibrium.
• Above 0.1 hPa, our cooling rates
exceed the heating rates, mainly due
to stronger cooling by C2H2 in ourmodel.

1-D calculation(From the difference ofheating/ cooling rates fordifferent temperature)

Daytime & nighttime,
Models A and C components

Radiative relaxation time

Cross correlation of subsolar latitude with thehemispheric temperature contrast (40°N40°S) from IRTF observation (1979—2001)[Simon-Miller et al., 2006]

250hPa(~2.5 years)

20hPa(~1 year)• The hemispheric temperature contrast
lags the solar forcing longer introposphere (~2.5 years) than instratosphere (~1 year), which means
the radiative relaxation time should be
longer in troposphere.
• Our model shows qualitatively
consistent results with the observation,
while a preceding study [Conrath et al.,1990] does not.

1-D calculation
Equation of solar heating ratein Conrath et al. [1990]

k-distribution

Radiative relaxation time

• The radiative relaxation timeby Conrath et al. [1990] wasshown to be longer in upper
atmosphere, which
contradicts the observations.
• It is because their model issimple and theheating/cooling rate isexpressed to be proportional
to the atmospheric density(pressure), which should
underestimate the radiative
effects in upper atmosphere.
← At the peaks of spectra, theabsorption coefficient becomesalmost constant against thepressure. (except the peaks,
proportional to pressute)1-D calculation
Different latitudes(with observations)Radiative-convective
equilibrium temperature

Different components (Model A, Model C,
Model A with twice more/less C2H2 and C2H6)• Radiative-convective equilibrium temperature is close to the observed verticalprofiles, except the top of stratosphere (due to the lack of non-LTE effects…?)• In higher latitude, the equilibrium temperature is several Kelvins colder than theequator in overall (the observed temperature field shows very small latitudinalanomaly). Note that the radiative effects of stratospheric hazes [e.g. Zhang et al.,2013], which may affect the temperature in high latitudes, are not included.
• In the upper stratosphere, it is sensitive to the components.

まとめ• 0.1～100hPa (下部・中部成層圏)では観測の温度
プロファイルで放射対流平衡が成り立ち、それは再現されている• それより上の高度はnon-LTEを考慮する必要あり？
成層圏・熱圏結合も検討 (JUICE SWI-RPWI連携)• 木星成層圏のヘイズの効果は未導入
将来的な導入は必要

放射加熱率[K/E. day]
ヘイズなし

ヘイズ加熱
導入

ヘイズ加熱
＋冷却導入

[Zhang et al., 2015]