2017/12/05 by Karen Aplin, K. L. Aplin, R. G. Harrison · 9 citations
Environmental Science · Physics and Astronomy · #Astro and Planetary Science #Astrobiology #Astronomy #Atmosphere (unit) #Atmospheric sciences #Environmental science #Isotope Analysis in Ecology #Meteorology #Physics #Planet #Planetary Science and Exploration #Uranus #Variation (astronomy) #physics.ao-ph #physics.space-ph
paper · pdf · doi:10.1002/2017gl075374
published in Geophysical Research Letters 44(24) (American Geophysical Union)
openalex publication_date 2017/12/05 · arxiv created 2017/12/19 · arxiv updated 2017/12/20 · openalex created_date 2021/02/01 · openalex updated_date 2026/08/05
Abstract Long‐term measurements (1972–2015) of the reflectivity of Uranus at 472 and 551 nm display variability that is incompletely explained by seasonal effects. Spectral analysis shows that this nonseasonal variability tracks the 11 year solar cycle. Two mechanisms could cause solar modulation: (a) nucleation onto ions or electrons created by galactic cosmic rays (GCR) or (b) UV‐induced aerosol color changes. Ion‐aerosol theory is used to identify expected relationships between reflectivity fluctuations and GCR flux, tested with multiple regression and compared to the linear response predicted between reflectivity and solar UV flux. The statistics show that 24% of the variance in reflectivity fluctuations at 472 nm is explained by GCR ion‐induced nucleation, compared to 22% for a UV‐only mechanism. Similar GCR‐related variability exists in Neptune's atmosphere; hence, the effects found at Uranus provide the first example of common variability in two planetary atmospheres driven through energetic particle modulation by their host star.