Numerical Simulations of Jupiter’s
Moist Convection Layer:Structure and Dynamics in
Statistically Steady States	
K. Sugiyama1), K. Nakajima2) ,M. Odaka3), K. Kuramoto3,5), Y. Hayashi4,5)1) ISAS/JAXA, JAPAN, 2) Kyushu Univ., JAPAN,
3) Hokkaido Univ., JAPAN, 4) Kobe Univ., JAPAN,
5) Center for Planetary Science

Japanese-French model studies ofplanetary atmospheres@Kobe

Introduction	

Introduction	• The mean vertical structure of the cloudlayer in Jupiter's atmosphere is thought
to be maintained by the statisticalcontribution of a large number of clouds
driven by internal and radiative heating/cooling over multiple cloud life cycles.
• However, the mean vertical structure andits relationship to cloud convection has
not been clarified yet.
– The thick visible clouds prevent thevertical structure of the entire cloudlayer to be observed by remotesensing.
– Galileo probe’s entry site is one of hot
spots which are cloudless region.

Lightning	lightning	Introduction	• The mean vertical structure of the cloudlayer in Jupiter's atmosphere is thought
to be maintained by the statisticalcontribution of a large number of clouds
driven by internal and radiative heating/cooling over multiple cloud life cycles.
• However, the mean vertical structure andits relationship to cloud convection has
not been clarified yet.
– The thick visible clouds prevent thevertical structure of the entire cloudlayer to be observed by remotesensing.
– Galileo probe’s entry site is one of hot
spots which are cloudless region.

Lightning	lightning	Fig. Convective clouds
observed by Galileo(Vasavada and Showman,2005)• The mean vertical profiles of theatmosphere have been
illustrated by the results
obtained using onedimensional equilibrium cloud
condensation models (ECCM)–Weidenschilling and Lewis (1973),
Atreya and Romani (1985)• But, atmospheric dynamics andcloud physical processes would
modify the features obtained by
ECCM.

H2O solidPressure (Pa)Introduction	

Fig. Vertical structure of Jupiter’s cloudobtained by the equilibrium cloud
condensation model (Atreya et al, 1999).

Three Cloud layers!	

Introduction	
• One of the important role ofcondensation is to form stablelayers• Molecular weight of eachcondensable gas (H2O, NH3, H2S)
is larger than that of major
component (H2 or He).
• If condensation occurs and thecondensate is removed byprecipitation, the mean molecularweight decreases and stable layer
is formed.
– Three-stable layers will exist inthe moist convection layer.

(NH3+H2S →NH4SH)	

Fig: Vertical profile of static stability
estimated by using ECCM. 	

In our study	¡ We have been developing cloud resolving model (deepconv)
that incorporates phase change and cloud microphysics.
¡ We investigate idealistic characteristics of convective motion
and mean vertical structure of the moist convection layer thatis established through a large number of life cycles of
convective clouds.
– Nakajima et al. (2000) [consider H2O only]– Sugiyama et al. (2009, 2011, 2014) [consider H2O, NH3,H2S]• In this presentation,– We demonstrate the temporal variation of thecharacteristics in the moist convection layer.
– The dependency on deep abundances of condensible
gases are also demonstrated.

Model &Setup of Exp.	

Numerical model	
• The dynamical framework of our model is two-dimensional in
the horizontal and vertical directions, and is based on thequasi-compressible system (Klemp and Wilhelmson, 1978).
– The system consists of the equations of motion, continuity
and thermodynamic and conservation equations ofcondensible species.
– Radiation transfer process is very crudely represented.
– Cloud microphysics process: The bulk parameterization
scheme (vapor, non-precipitating and precipitatingcondensates) of Kessler (1969) that is well-used in Earth’s
atmospheric simulation is used.
vapor	

precipitating	

non-precipitating	Set-up of the experiments	

Altitude	• The balance among the upwelling heat
flux from the deep interior, the upward
heat transport by moist convection, andnet radiative cooling caused by solar andlong-wave radiation is considered.
– The effect of the heat supply from thedeep interior is realized by keeping thevalues of the potential temperature andmixing ratios constant at the lower
boundary.
– The net radiative cooling is simply
represented as horizontally andtemporally uniform body cooling at theupper troposphere.	

body cooling	

convective
heating	Constant Temperature& abundances	Set-up of the experiments	
• Cooling rate (Qrad):-0.01 K/day (typical value)-0.1 K/day
300km
relative humidity• deep abundances:
75 %200km
0.1bar1 x solar
cooling
3 x solar
layer	
10 x solar
140km 2 bar– The solar values aretaken from Grevesse etal. (2007).
• Integral time
H2S NH3 H2O– about 3 years 	
30 bar300 Km (Δz = 2 km)

1024 km (Δx =2 km)

T= 160K(0.6 bar)

T=490 kInitial potential
temperature（θ）	

Initial mixing ratios(1, 3,10 times solar)	

Results	
We show the results of Control Exp. (CTRL)
using Qrad = -0.01 K/day and deep abundance is
1 x solar.	

Animation	
0.120	0.120	

Horizontal average	• The convective activity of thewhole layer is not steady but
quasi-periodic with a period ofCondensates	
about 40 days.
0.1
0– We will refer the time when
the active cloud convection
occurs as `active period' (A)AQA	-100	and the other as `quiet
20	
period’ (Q).
Virtual potential temperature	• The value of virtual potential
0.1
temperature rapidly increases
0during the active periods, anddecreases steadily with time
during the quiet period.
AQA	 -100	
20	

Development of clouds (1)	• At the beginning of quiet
period, moist convection
associated with NH3
condensation occurs and20	
the NH3 clouds are
0.1
distributed horizontally.
– Vertical motion is weak(w = ~ 5 m/s)
0.1

Condensates	
NH3-100	
Condensible gases	
NH3H2S

20	

• Note that the vertical
0.1
motion in the sub-cloudlayer is the remnant of
convective motion driven
during an active period.
20	0

Vertical velocity	

0H2O	-100	

w20-100	Development of clouds (2)	• As time progresses,
NH4SH clouds appear,
followed by H2O clouds.
• Mixing of different
condensable gases andcondensates across theNH3 LCL or NH4SH LCL isweak, but occurs
occasionally due to theupward or downward
penetration of convectiveplumes.
– LCL is “liftingcondensation level”.

0.1

Condensates	
H2O	

NH3
NH4SH 0-100	

20	0.1

Condensible gases	
NH3H2S

20	0.1

Vertical velocity	

0H2O	-100	

w2020	-100	Development of clouds (3)	• Following the onset ofNH4SH clouds, stronger
H2O clouds begin to formand become localized.
– The base of H2O
cloud is deeper thanthe previous time.
• Distribution ofcondensible gases is stillalmost horizontallyuniform.
– Mixing of different
condensible gases
across the NH3 LCL orNH4SH LCL is stillweak.

0.1

Condensates	
NH3NH4SH 0H2O	-100	

20	0.1

Condensible gases	
NH3H2S

20	0.1

Vertical velocity	

0H2O	-100	

w2020	-100	Development of clouds (4)	• H2O active clouds develop 0.1

from the H2O LCL.
• The vertical motion in themoist convection layer is 20	
characterized by narrow,
0.1
strong, cloudy updrafts
and wide, weak, dry
downdrafts.
• H2O LCL continues to acts 20	
as a significant dynamical0.1
and compositionalboundary.
– Stable layer is exists– Updrafts and20	
downdrafts penetrate
the NH3 and NH4SHLCLs.

Condensates	
NH3NH4SH
H2O	-100	

Condensible gases	
NH3H2S

Vertical velocity	

0H2O	-100	

w20
H2O LCL	-100	

Time & horizontal average 	• Considerable amounts of H2O and NH4SH cloud particles areobserved above the NH3 LCL.
• The mixing ratios of NH3 and H2S start to decrease with height
not at their respective LCLs but at the H2O LCL.
• These characteristics are not the same as that of ECCM.

ー NH3ー H2S
ー H2O	

solid: mean
broken: active
perioddashed: quiet
period	

ー NH3
ー NH4SHー H2O	

solid: mean
broken:ECCMDependency on deepabundance	The body cooling rate is set to be 10 times larger
than that of CTRL in order to save the CPU time.

Dependency on deepabundances	• The results of the series of calculation arequalitatively similar to that of CTRL.
• The period of the quasi-periodic cycle isroughly proportional to the deep abundanceof H2O vapor.

deep abundances(solar)

period (day)	 ratio 	R10	1	

9	1	R10S3	3	19	2.1	

R10S10	10	139	16	

Discussion &Conclusion	Why intermittent?	
• Active cloud development is terminated when the instability iscompletely exhausted.
– An integral measure of convective instability (A) increase in thequiet periods and decrease rapidly in the active periods.
– At the end of the active periods, A is almost zero.
*Virtual potential temperature	0.1
020	800	

A = ∫ ρg (Tv − Tv ) /Tv dz-100	

€850	
• The trigger of active convections are H2O condensate that falls
down through the H2O LCL.
– The upward flow driven by H2O re-evaporation carry moist airfrom below to the moist convection layer.

• The period of intermittency is roughly equal to the time
obtained by dividing the mean temperature increase by thebody cooling rate.

Summary	
• Active cloud convection occurs intermittently.
–The existence of vigorous cumulonimbus clouds is supported by several recent
observational studies (Gierasch et al., 2000; Simon-Miller et al., 2000; Sromovsky and Fry, 2010).

• The H2O condensation level acts as a steady kinematic andcompositional boundary because of the strong stable layerassociated with the H2O condensation.
–The present results do not reproduce the observation made by the Galileo probethat all condensable gases are depleted below the H2O LCL (Wong et al., 2004).
– Dry air parcels can rarely penetrate below the H2O LCL, since the H2O LCL acts asa strong dynamical and compositional boundary.

• The averaged vertical profiles of clouds and condensible gases aredistinctly different from those predicted by ECCM.
–By considering the vertical mixing due to convection, the small NH3 abundance
derived from analysis of radio observation (Pater et al., 2001, Gibson et al., 2005) can beexplained.

• The period of the quasi-periodic cycle is roughly proportional to thedeep abundance of H2O gas.