Rotational modulation and local time dependence of Saturn's infrared H 3 + auroral intensity
Rotational modulation and local time dependence of Saturn's infrared H 3 + auroral intensity
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土星红外H 3 极光强度的旋转调制和本地时间依赖性
DOI：
10.1029/2012ja017990
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Badman S
中科院分区：
文献类型：
--
作者：
Badman S
行星极光辐射揭示了磁层场向电流系统的结构。在这项研究中，卡西尼视觉和红外测绘光谱仪（VIMS）对土星春分前红外H3+极光的观测进行了分析，以显示（a）两个半球极光强度的旋转调制和（B）发射强度的显着当地时间依赖性。在每个半球的极光电流系统的“行星周期”旋转调制的发射强度。北方极光强度对南方旋转气流系统的反相依赖性也较小，表明南方气流系统的一部分在北方半球闭合。南半球的极光在黎明后的区域最为强烈，这与过去对极光场向电流、紫外极光和SKR发射功率的一些测量结果一致。对北方极光强度的相应调查显示，黎明至中午的增强范围更广，这可能是由于南部旋转电流系统与北部旋转电流系统的相互作用。在黄昏和午夜后，两个半球的极光强度都有所减弱。这些观测结果可以通过每个半球的旋转场向电流系统与当地时间固定的电流系统的相互作用来解释，这与太阳风与磁层场线的相互作用有关。
Planetary auroral emissions reveal the configuration of magnetospheric field‐aligned current systems. In this study, Cassini Visual and Infrared Mapping Spectrometer (VIMS) observations of Saturn's pre‐equinox infrared H3+aurorae were analysed to show (a) rotational modulation of the auroral intensity in both hemispheres and (b) a significant local time dependence of the emitted intensity. The emission intensity is modulated by the ‘planetary period’ rotation of auroral current systems in each hemisphere. The northern auroral intensity also displays a lesser anti‐phase dependence on the southern rotating current system, indicating that part of the southern current system closes in the northern hemisphere. The southern hemisphere aurorae were most intense in the post‐dawn sector, in agreement with some past measurements of auroral field‐aligned currents, UV aurora and SKR emitted power. A corresponding investigation of the northern hemisphere auroral intensity reveals a broader dawn‐noon enhancement, possibly due to the interaction of the southern rotating current system with that of the north. The auroral intensity was reduced around dusk and post‐midnight in both hemispheres. These observations can be explained by the interaction of a rotating field‐aligned current system in each hemisphere with one fixed in local time, which is related to the solar wind interaction with magnetospheric field lines.