1. Saturn temperature and H2 profiles from Solar EUV occultations
Jacques Gustin
Jacques Gustin – UVIS team meeting – Boulder June 27-29

2.  What can be learned from Solar occs in EUV?
 which absorbing species attenuate the emission in EUV?
Jacques Gustin – UVIS team meeting – Boulder June 27-29

3. Absorption dominated by H2 in <1120 Å, HC >1120 Å
In Å: H2 bands (Greathouse et al., 2010 stellar occ jupiter New Horizons)
transmission in Å informs on H2 structure and T structure
Jacques Gustin – UVIS team meeting – Boulder June 27-29

4. Method:  Create a synthetic T profile: T0: asymptotic T high P
T: asymptotic T low P
Zm: altitude of max gradient
: ~ gradient dT/dz
Derive H2 density profile from T profile assuming hydrostatic
equilibrium. Last parameter needed: nH2(z*)
Jacques Gustin – UVIS team meeting – Boulder June 27-29

5. Application to the observations:
S, n2(s),T(s)
LOS
UVIS
abs. Spec.
Unabs. Spec.
MRH
1 bar
start with unabsorbed solar spectrum and T, H2 profiles from start values of the 5 parameters
for each MRH: total tau =
 = (H2(s), T) ; (H2LW)  templates for all J of v"=0
get an absorbed spectrum for each MRH (= transmission curve)
parameters vary until min 2
Jacques Gustin – UVIS team meeting – Boulder June 27-29

6.  Observations:
Jacques Gustin – UVIS team meeting – Boulder June 27-29

7.  8 cases:
medium lat.
high lat.
250 km

8.  Results:
Jacques Gustin – UVIS team meeting – Boulder June 27-29

9. Jacques Gustin – UVIS team meeting – Boulder June 27-29

10.  Best parameters:
Jacques Gustin – UVIS team meeting – Boulder June 27-29

11. ACS
FUSE
FUSE

13. Jacques Gustin – UVIS team meeting – Boulder June 27-29

14. Conclusions: - Exospheric T higher than expected
- Exospheric T not higher for high lats
- T & H2 profiles different for high/med. lats
(from T gradient)
- Variability with latitude & seasons
Next: - sensitivity study
- apply method to Voyager occs
- simulate HC profiles with these T profiles
(implication for auroral studies)
Jacques Gustin – UVIS team meeting – Boulder June 27-29