Uranus's Northern Polar Cap in 2014

Daniel Toledo*, Patrick G.J. Irwin, Nicholas A. Teanby, Amy A. Simon, Michael H. Wong, Glenn S. Orton

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

10 Citations (Scopus)
294 Downloads (Pure)


In October and November 2014, spectra covering the 1.436 to 1.863-μm wavelength range from the SINFONI Integral Field Unit Spectrometer on the Very Large Telescope showed the presence of a vast bright north polar cap on Uranus, extending northward from about 40°N and at all longitudes observed. The feature, first detected in August 2014 from Keck telescope images, has a morphology very similar to the southern polar cap that was seen to fade before the 2007 equinox. At strong methane-absorbing wavelengths (for which only the high troposphere or stratosphere is sampled) the feature is not visible, indicating that it is not a stratospheric phenomenon. We show that the observed northern bright polar cap results mainly from a decrease in the tropospheric methane mixing ratio, rather than from a possible latitudinal variation of the optical properties or abundance of aerosol, implying an increase in polar downwelling near the tropopause level.

Original languageEnglish
Pages (from-to)5329-5335
Number of pages7
JournalGeophysical Research Letters
Issue number11
Early online date14 Jun 2018
Publication statusPublished - 16 Jun 2018


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