2023NatAs...7.1048C

The localized delivery of new long-lived species to Jupiter's stratosphere by comet Shoemaker-Levy 9 in 1994 opened a window to constrain Jovian chemistry and dynamics by monitoring the evolution of their vertical and horizontal distributions. However, the spatial distributions of CO and HCN, two of these long-lived species, had never been jointly observed at high latitudinal resolution. Atacama large millimeter/submillimeter array observations of HCN and CO in March 2017 show that CO was meridionally uniform and restricted to pressures lower than 3 ± 1 mbar. HCN shared a similar vertical distribution in the low- to mid-latitudes, but was depleted at pressures between 2+2-12-1+2{2}_{-1}^{+2} and 0.04+0.07-0.030.04-0.03+0.07{0.04}_{-0.03}^{+0.07} mbar in the aurora and surrounding regions, resulting in a drop by two orders of magnitude in column density. We propose that heterogeneous chemistry bonds HCN on large aurora-produced aerosols at these pressures in the Jovian auroral regions causing the observed depletion.