We report on results of an observing campaign to support the Juno mission .
At the beginning of 2016 , using TEXES ( Texas Echelon cross-dispersed Echelle Spectrograph ) , mounted on the NASA Infrared Telescope Facility ( IRTF ) , we obtained data cubes of Jupiter in the 1930–1943 cm ^ { -1 } spectral ranges ( around 5 \mu m ) , which probe the atmosphere in the 1–4 bar region , with a spectral resolution of \approx 0.15 cm ^ { -1 } and an angular resolution of \approx 1.4 ” .
This dataset is analysed by a code that combines a line-by-line radiative transfer model with a non-linear optimal estimation inversion method .
The inversion retrieves the vertical abundance profiles of NH _ { 3 } — which is the main contributor at these wavelengths — with a maximum sensitivity at \approx 1–3 bar , as well as the cloud transmittance .
This retrieval is performed on more than one thousand pixels of our data cubes , producing maps of the disk , where all the major belts are visible .
We present our retrieved NH _ { 3 } abundance maps which can be compared with the distribution observed by Juno ’ s MWR ( ) in the 2 bar region and discuss their significance for the understanding of Jupiter ’ s atmospheric dynamics .
We are able to show important latitudinal variations — such as in the North Equatorial Belt ( NEB ) , where the NH _ { 3 } abundance is observed to drop down to 60 ppmv at 2 bar — as well as longitudinal variability .
In the zones , we find the NH _ { 3 } abundance to increase with depth , from 100 \pm 15 ppmv at 1 bar to 500 \pm 30 ppmv at 3 bar .
We also display the cloud transmittance–NH _ { 3 } abundance relationship , and find different behaviour for the NEB , the other belts and the zones .
Using a simple cloud model ( ) , we are able to fit this relationship , at least in the NEB , including either NH _ { 3 } -ice or NH _ { 4 } SH particles with sizes between 10 and 100 \mu m .