Comparative Planetary Science
Storm clouds in the atmospheres of Uranus and Neptune observed with VLT/SINFONI
Patrick G J Irwin
Leigh Fletcher (U. of Leicester), Glenn Orton (JPL), Nick Teanby (U. of Bristol)
University of Oxford (Atmospheric, Oceanic and Planetary Physics)
Near infrared observations of the clouds of Uranus and Neptune (sometimes known as the Ice Giants) have been made recently with SINFONI on ESO’s Very Large Telescope (VLT) in Chile. SINFONI is an Integral Field Unit spectrometer, recording 64 x 64 pixel images with 2048 wavelengths/pixel using adaptive optics. H-band (1.43 – 1.87 micron) image 'cubes', obtained at spatial resolutions of ∼ 0.1" per pixel, can be used to explore the vertical distribution of clouds/hazes in these planets' atmospheres through fitting the observed spectra with our radiative transfer and retrieval code, NEMESIS. Our observations show that both planets have a thick, mostly uniform cloud layer at the 2-3 bar pressure level, which is thought to be composed mostly of H2S. At higher altitudes, Neptune has thick, high cloud belts in mid-latitude 'zones' at 20-40S and 20-40N, with lower, thinner clouds seen nearer the equator, together with occasional deep clouds (at 1-3 bars) seen near the south pole or at the edge of the main cloud zones. Uranus' atmosphere is found to be generally less dynamic, but seasonal changes in the reflectivity of the polar regions have been detected and occasional bright storms are seen at mid-latitudes, one of which was observed with SINFONI in 2014 immediately after its discovery by amateur observers. We will review our recent observations of both these planets, highlighting the surprising similarities and differences in the clouds observed in the atmospheres of the Ice Giants.
16:30 - 18:00
EX - LT3 (320)