The dynamics of planetary atmospheres Theoretical concept is formulated in the Geophysical Fluid Dynamics – the dynamics of stratified fluid on a rotating sphere
Hadley cell circulation Solar flux easterly (passat) flow tidal buldge convective flow westerly jet
“Primitive” equations: fluid on a rotating sphere momentum energy continuity eqn. of state modifications absolute vorticity Boussinesq approximation: everywhere but gravity
Spherical coordinate system: z, w y, v x, u
Useful numbers Coriolis parameter -plane approximation Rossby parameter Rossby number
Adjustments equation of horizontal motion geostrophic approximaton hydrostatic approximation
Ro << 1 thermal wind equation Opposite case: Ro >> 1 cyclostrophic approximation
Wave motion in the atmosphere Elasticity sound Buoyancy gravity waves Coriolis force inertial waves Planetary-scale forced oscillations of any type are called tides
acoustic waves
gravity waves -potential temperature Brunt-Vajsala frequency For non-vertically propagating waves, Group velocity
Rossby waves Search for the solution in form
Eliminating P and use incompressibility,
Solsticial circulation on Mars Solar flux thermal tide westerly jet Rossby waves
Ls = 92, North hemisphere [kg/m2] Water vapor column: Ls = 92, North hemisphere [kg/m2] 0 180
Ls = 113, North hemisphere [kg/m2] Water vapor column: Ls = 113, North hemisphere [kg/m2] 0 180
Ls = 143, North hemisphere [kg/m2] Water vapor column: Ls = 143, North hemisphere [kg/m2] 0 180
OMEGA observations of the residual seasonal frost around South pole OMEGA observations of the residual seasonal frost around South pole. Ls = 236-243 1.5 m band depth
Ls=93-97 Ls=113-115 Ls=127-136
Cyclonic vortices Anticyclonic vortex
Venus case (symmetric mode) multiple Hadley cells? VIRTIS image of the Southern Polar vortex @ 5.0 µm convective flow thermal tide superrotation
VIRTIS image of the Southern Polar vortex @ 5.0 µm
Titan: another superrotating atmosphere Mingalev et al., 2008
Vertical velocity on Titan: a signature of thermal tide z=550 km
Giant planets zones belts
Hot spot
Polar vortex
32 km/pix