A076-12
The atmosphere of Jupiter in the infrared observed by Juno/JIRAM
Abstract:
JIRAM (the Jovian InfraRed Auroral Mapper) is an infrared camera and a spectrometer on board the Juno spacecraft.
JIRAM works in the 2-5 μm spectral range and is built to study both the infrared aurora of Jupiter and its atmosphere. Since the orbit insertion, JIRAM has performed several observations of the planet from the equator to poles. Unprecedented views of the polar atmospheric structures have been acquired for the 1st time thanks to the unique orbital design of the Juno mission.
The spectroscopic observations are used for studying atmospheric dynamical structures and for investigating the abundance of some chemical species that have importance in the atmosphere’s chemistry, microphysics and dynamics,such as water, ammonia, phosphine, germane and arsine.
Spectral measurements provided the opportunity to measure abundances of minor atmospheric species at all latitudes down to pressures of 4-5 bars.
Limb observations at the low latitudes permit investigating the abundances of methane and trihydrogen cation in the stratosphere and the thermosphere of the planet.
Recent analysis, done over a period of roughly 1.5 years on polar cloud opacities, suggests a quasi-geostrophic two-
In the north polar region, Juno discovered, in 2017, the presence of an eight-cyclone structure around a single polar cyclone; in the south, one polar cyclone is encircled by five circumpolar cyclones. The stability of these structures has been tracked for more than 3 years now. Recent observations, performed in late 2019, showed that South Pole configuration has temporarily changed: the structure has shifted to a hexagon for a few months, before moving back to the original pentagon shape. In the north there are significant hints that the octagonal shape may have been lost for a similar period of time. The implications of these transient deviations from symmetric shapes, which seem to be an apparent equilibrium condition, are discussed.