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DOI | 10.1002/2017GL075374 |
Solar-Driven Variation in the Atmosphere of Uranus | |
Aplin, K. L.1; Harrison, R. G.2 | |
2017-12-28 | |
发表期刊 | GEOPHYSICAL RESEARCH LETTERS
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ISSN | 0094-8276 |
EISSN | 1944-8007 |
出版年 | 2017 |
卷号 | 44期号:24 |
文章类型 | Article |
语种 | 英语 |
国家 | England |
英文摘要 | Long-term measurements (1972-2015) of the reflectivity of Uranus at 472 and 551nm display variability that is incompletely explained by seasonal effects. Spectral analysis shows that this nonseasonal variability tracks the 11year 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 472nm 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. Plain Language Summary Measurements of the planets Uranus and Neptune have been made using a telescope, for every year from 1972 to 2015. How bright a planet appears to us is an indicator of the cloud cover in its atmosphere. An 11 year brightness variation was spotted in the Neptune observations many years ago, indicating that a process linked to the the Sun's 11 year activity cycle affects the planet's clouds. This inspired us to look at the data for Uranus more closely, and we found the same signal as for Neptune. There are two possible explanations. One possibility is chemical, when light from the Sun affects the color of particles in the planet's atmosphere. Our other possibility is that energetic particles from outside the solar system, cosmic rays, influence particle, or cloud formation. (Cosmic rays are bent away from the solar system by the Sun acting as a magnet, so are also affected by its 11 year activity cycle). In our results, we actually find that both of them have a small effect on the clouds on Uranus. This is the first evidence of two planetary atmospheresNeptune originally and now Uranusshowing similar variations, in both cases originating from their host star. |
英文关键词 | ionization cosmic rays aerosol nucleation |
领域 | 气候变化 |
收录类别 | SCI-E |
WOS记录号 | WOS:000422954700034 |
WOS关键词 | SPECTRAL-ANALYSIS ; NEPTUNE ; VARIABILITY |
WOS类目 | Geosciences, Multidisciplinary |
WOS研究方向 | Geology |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/27178 |
专题 | 气候变化 |
作者单位 | 1.Univ Oxford, Dept Phys, Oxford, England; 2.Univ Reading, Dept Meteorol, Reading, Berks, England |
推荐引用方式 GB/T 7714 | Aplin, K. L.,Harrison, R. G.. Solar-Driven Variation in the Atmosphere of Uranus[J]. GEOPHYSICAL RESEARCH LETTERS,2017,44(24). |
APA | Aplin, K. L.,&Harrison, R. G..(2017).Solar-Driven Variation in the Atmosphere of Uranus.GEOPHYSICAL RESEARCH LETTERS,44(24). |
MLA | Aplin, K. L.,et al."Solar-Driven Variation in the Atmosphere of Uranus".GEOPHYSICAL RESEARCH LETTERS 44.24(2017). |
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