Deep, Closely-Packed, Long-Lived Cyclones on Jupiter's Poles

Juno Mission to Jupiter has found closely-packed cyclones at the planet's two poles. The observation that these cyclones coexist in very confined space, with outer rims almost touching each other but without merging, poses a big puzzle. In this work, we present numerical calculations showing that convectively sustained, closely-packed cyclones can form and survive without merging for a very long time in polar region of a deep rotating convection zone (for thousands of planetary rotation periods). Through an idealized application of the inertial stability criterion for axisymmetric circulations, it is found that the large Coriolis parameter near the pole plays a crucial role in allowing the cyclones to be packed closely.