We have obtained high-resolution spectra of Jupiter ’ s Great Red Spot ( GRS ) between 4.6 and 5.4 \mu m using telescopes on Mauna Kea in order to derive gas abundances and to constrain its cloud structure between 0.5 and 5 bars .
We used line profiles of deuterated methane ( CH _ { 3 } D ) at 4.66 \mu m to infer the presence of an opaque cloud at 5 \pm 1 bars .
From thermochemical models this is almost certainly a water cloud .
We also used the strength of Fraunhofer lines in the GRS to obtain the ratio of reflected sunlight to thermal emission .
The level of the reflecting layer was constrained to be at 570 \pm 30 mbars based on fitting strong NH _ { 3 } lines at 5.32 \mu m. We identify this layer as an ammonia cloud based on the temperature where gaseous NH _ { 3 } condenses .
We found evidence for a strongly absorbing , but not totally opaque , cloud layer at pressures deeper than 1.3 bars by combining Cassini/CIRS spectra of the GRS at 7.18 \mu m with ground-based spectra at 5 \mu m. This is consistent with the predicted level of an NH _ { 4 } SH cloud .
We also constrained the vertical profile of H _ { 2 } O and NH _ { 3 } .
The GRS spectrum is matched by a saturated H _ { 2 } O profile above an opaque water cloud at 5 bars .
The pressure of the water cloud constrains Jupiter ’ s O/H ratio to be at least 1.1 times solar .
The NH _ { 3 } mole fraction is 200 \pm 50 ppm for pressures between 0.7 and 5 bars .
Its abundance is 40 ppm at the estimated pressure of the reflecting layer .
We obtained 0.8 \pm 0.2 ppm for PH _ { 3 } , a factor of 2 higher than in the warm collar surrounding the GRS .
We detected all 5 naturally occurring isotopes of germanium in GeH _ { 4 } in the Great Red Spot .
We obtained an average value of 0.35 \pm 0.05 ppb for GeH _ { 4 } .
Finally , we measured 0.8 \pm 0.2 ppb for CO in the deep atmosphere .