DOI: 10.1002/2017JE005419
Scopus记录号: 2-s2.0-85041040658
论文题名: Equatorial Oscillation and Planetary Wave Activity in Saturn's Stratosphere Through the Cassini Epoch
作者: Guerlet S. ; Fouchet T. ; Spiga A. ; Flasar F.M. ; Fletcher L.N. ; Hesman B.E. ; Gorius N.
刊名: Journal of Geophysical Research: Planets
ISSN: 21699097
出版年: 2018
卷: 123, 期: 1 起始页码: 246
结束页码: 261
语种: 英语
英文关键词: atmosphere
; Cassini
; infrared remote sensing
; Saturn
; stratospheric dynamics
Scopus关键词: equatorial wave
; infrared spectroscopy
; planetary wave
; quasi-biennial oscillation
; remote sensing
; Rossby wave
; Saturn
; stratosphere
英文摘要: Thermal infrared spectra acquired by Cassini/Composite InfraRed Spectrometer (CIRS) in limb-viewing geometry in 2015 are used to derive 2-D latitude-pressure temperature and thermal wind maps. These maps are used to study the vertical structure and evolution of Saturn's equatorial oscillation (SEO), a dynamical phenomenon presenting similarities with the Earth's quasi-biennal oscillation (QBO) and semi-annual oscillation (SAO). We report that a new local wind maximum has appeared in 2015 in the upper stratosphere and derive the descent rates of other wind extrema through time. The phase of the oscillation observed in 2015, as compared to 2005 and 2010, remains consistent with a ∼15 year period. The SEO does not propagate downward at a regular rate but exhibits faster descent rate in the upper stratosphere, combined with a greater vertical wind shear, compared to the lower stratosphere. Within the framework of a QBO-type oscillation, we estimate the absorbed wave momentum flux in the stratosphere to be on the order of ∼7 × 10−6 N m−2. On Earth, interactions between vertically propagating waves (both planetary and mesoscale) and the mean zonal flow drive the QBO and SAO. To broaden our knowledge on waves potentially driving Saturn's equatorial oscillation, we searched for thermal signatures of planetary waves in the tropical stratosphere using CIRS nadir spectra. Temperature anomalies of amplitude 1–4 K and zonal wave numbers 1 to 9 are frequently observed, and an equatorial Rossby (n = 1) wave of zonal wave number 3 is tentatively identified in November 2009. ©2018. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/114868
Appears in Collections: 气候减缓与适应
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作者单位: LMD/IPSL, Sorbonne Universités, UPMC Univ Paris 06, ENS, PSL Research University, École polytechnique, Université Paris Saclay, CNRS, Paris, France; LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, Meudon, France; Institut Universitaire de France, Paris, France; NASA/GSFC, Greenbelt, MD, United States; Department of Physics and Astronomy, University of Leicester, Leicester, United Kingdom; StScI, Baltimore, MD, United States
Recommended Citation:
Guerlet S.,Fouchet T.,Spiga A.,et al. Equatorial Oscillation and Planetary Wave Activity in Saturn's Stratosphere Through the Cassini Epoch[J]. Journal of Geophysical Research: Planets,2018-01-01,123(1)