Cassini UVIS observations of Titan ultraviolet airglow intensity dependence with solar zenith angle
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- 作者：E. M. Royer ; J. M. Ajello ; G. M. Holsclaw ; R. A. West ; L. W. Esposito ; E. T. Bradley
- 刊名：Geophysical Research Letters
- 出版年：2017
- 出版时间：16 January 2017
- 年：2017
- 卷：44
- 期：1
- 页码：88-96
- 全文大小：1.3MB
- ISSN：1944-8007
文摘
The Cassini Ultraviolet Imaging Spectrometer (UVIS) observed the airglow (dayglow and nightglow) of Titan over a range of solar zenith angles (SZA) from 14 to 150° on five separate observations obtained between 2008 and 2012. The modeling of the solar cycle normalized UVIS observations indicates that a Chapman layer function provides a satisfactory fit to the intensity of the EUV and FUV airglow molecular emissions of the N2 Lyman-Birge-Hopfield band system (LBH math-equation-construct">mage="true" class="math-equation-image">mathml="true" class="math-equation-mathml" style="display:none"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><msup xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="normal">ami><mn>1mn>msup><msub xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML"><mi>Πmi><mi mathvariant="normal">gmi>msub><mo xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">→mo><msup xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="normal">Xmi><mn>1mn>msup><msubsup xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="true">∑mo><mi mathvariant="normal">gmi><mo form="prefix">+mo>msubsup>mml:math>), the Carroll-Yoshino band system ( math-equation-construct">mage="true" class="math-equation-image">mathml="true" class="math-equation-mathml" style="display:none"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><msup xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML"><msubsup><mi mathvariant="normal">cmi><mn>4mn><mo>′mo>msubsup><mn>1mn>msup><msubsup xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="true">∑mo><mi mathvariant="normal">umi><mo form="prefix">+mo>msubsup><mo xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML">→mo><msup xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="normal">Xmi><mn>1mn>msup><msubsup xmlns:w="http://www.wiley.com/namespaces/wiley" xmlns:wiley="http://www.wiley.com/namespaces/wiley/wiley" xmlns:cr="urn://wiley-online-library/content/render" xmlns="http://www.w3.org/1998/Math/MathML"><mo stretchy="true">∑mo><mi mathvariant="normal">gmi><mo form="prefix">+mo>msubsup>mml:math>), and of several atomic multiplets of nitrogen (NI, II) as a function of SZA. This result shows that the strongest contribution to the Titan dayglow occurs by processes (photoelectrons and photodissociation) involving the solar EUV flux rather than magnetospheric particle precipitation that dominates emission excitation in the nightglow.