High latitude temperatures in Saturn’s upper atmosphere published until recently had values below ∼460 K (Melin et al., 2007; Vervack and Moses, 2012), but Melin et al. (2011) and Stallard et al. (2012) have shown that H3+ emission may be brighter than previously indicated, and temperatures hotter. Using high resolution Cassini Visual and Infrared Mapping Spectrometer (VIMS) images, Melin et al. (2011) inferred temperatures of a segment of the auroral oval of 440 ± 50 K. Even higher temperatures in Saturn’s auroral oval of (563–624) ± 30 K were derived from Cassini VIMS observations by Stallard et al. (2012), so auroral temperatures on Saturn up to around 650 K are within the observed range. The thick red line in the upper panel Fig. 12 highlights the 650 K contour line and thus roughly separates values of polar temperatures that have been observed on Saturn (T ⩽ 650 K) from those that as yet have not been observed (T > 650 K).
Saturn’s upper atmosphere
High latitude temperatures
below ∼460 K
K
auroral oval
inferred temperatures
440 ± 50 K
K
Saturn’s auroral oval
temperatures
(563–624) ± 30 K
K
Saturn
auroral temperatures
up to around 650 K
K
Saturn
polar temperatures
650 K
K
Saturn
polar temperatures
⩽ 650 K
K
Saturn
polar temperatures
> 650 K
K