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. 2022 Jul 20;8(29):eabm4665. doi: 10.1126/sciadv.abm4665

Table 1. Model parameters used in our study.

Symbol Name Definition/value
Enceladus parameters
a Radius 252 km
δ Obliquity 27°
H Global mean ice thickness 20.8 km: (18)
D Global mean ocean depth 39.2 km: (18)
Ω Rotation rate 5.307 × 10−5 s−1
g 0 Surface gravity 0.113 m/s2
Ts¯ Mean surface temperature 59 K
Europa parameters
a Radius 1561 km
δ Obliquity 3.1°
H Global mean ice thickness 15 km: (53)
D Global mean ocean depth 85 km: (53)
Ω Rotation rate 2.05 × 10−5 s−1
g 0 Surface gravity 1.315 m/s2
Ts¯ Mean surface temperature 110 K
Physical constants
L f Fusion energy of ice 334,000 J/kg
Cp Heat capacity of water 4000 J/kg per Kelvin
Tf(S, P) Freezing point Eq. 14
ρi Density of ice 917 kg/m3
ρw Density of the ocean Eq. 12
α, β Thermal expansion and saline contraction coeff. Using Gibbs Seawater Toolbox: (23)
κ0 Conductivity coeff. of ice 651 W/m: (74)
p α Ice dissipation amplification factor −2 to −1
ηm Ice viscosity at freezing point 1014 Ps·s
Default parameters in the ocean model
νh, νv Horizontal/vertical viscosity 10 m2/s
ν~h,ν~v Biharmonic hyperviscosity 109 m4/s
κh, κv Horizontal/vertical diffusivity 0.005 m2/s
T, γS, γM) Water-ice exchange coeff. for T, S, and momentum (10−5, 10−5, 10−3) m/s
g Gravity in the ocean Eq. 8
P 0 Reference pressure ρig0H = 2.16 × 106 Pa
θ0 Reference potential temperature Tf(S0, P0)
ρw0 Reference density of ocean Eq. 13
cond Conductive heat loss through ice Eq. 15, Fig. 7
ice Tidal heating produced in the ice Eq. 26, Fig. 7
core Bottom heat flux powered by the core Eq. 16, Fig. 7
A Surface albedo 0.81
T s Surface temperature profile Fig. 7