Jupiter’s Equatorial Plumes and Hot Spots: Spectral Mapping from
Gemini/TEXES and Juno/MWR
Abstract
We present multi-wavelength measurements of the thermal, chemical, and
cloud contrasts associated with the visibly dark formations (also known
as 5-µm hot spots) and intervening bright plumes on the boundary between
Jupiter’s Equatorial Zone (EZ) and North Equatorial Belt (NEB).
Observations made by the TEXES 5-20 µm spectrometer at the Gemini North
Telescope in March 2017 reveal the upper-tropospheric properties of 12
hot spots, which are directly compared to measurements by Juno using the
Microwave Radiometer (MWR), JIRAM at 5 µm, and JunoCam visible images.
MWR and thermal-infrared spectroscopic results are consistent near 0.7
bar. Mid-infrared-derived aerosol opacity is consistent with that
inferred from visible-albedo and 5-µm opacity maps. Aerosol contrasts,
the defining characteristics of the cloudy plumes and aerosol-depleted
hot spots, are not a good proxy for microwave brightness. The hot spots
are neither uniformly warmer nor ammonia-depleted compared to their
surroundings at p<1 bar. At 0.7 bar, the microwave brightness
at the edges of hot spots is comparable to other features within the
NEB, whereas they are brighter at 1.5 bar, signifying either warm
temperatures and/or depleted NH3 at depth. Temperatures and ammonia are
spatially variable within the hot spots, so the precise location of the
observations matters to their interpretation. Reflective plumes
sometimes have enhanced NH3, cold temperatures, and elevated aerosol
opacity, but each plume appears different. Neither plumes nor hot spots
had microwave signatures in channels sensing p>10 bars,
suggesting that the hot-spot/plume wave is a relatively shallow feature.