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首页> 外文期刊>Planetary and space science >Observations of upper tropospheric acetylene on Saturn: No apparent correlation with 2000 km-sized thunderstorms
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Observations of upper tropospheric acetylene on Saturn: No apparent correlation with 2000 km-sized thunderstorms

机译：土星上对流层上层乙炔的观测：与2000公里雷暴没有明显关系

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摘要

Thunderstorm activity has been observed on Saturn via radio emissions from lightning discharges and optical detections of the lightning flashes on the planet's nightside. Thunderstorms provide extreme environments in which specific atmospheric chemistry can be induced-namely through energy release via lightning discharges, and fast vertical transport resulting in rapid advection of tropospheric species. It is thus theorised that certain atmospheric trace species - such as C_2H_2, HCN, and CO - can be generated in the troposphere by large bursts of energy in the form of lightning, and transported upward towards the upper troposphere by the extreme dynamics of thunderstorms, where they should be observable by satellite instruments. In this work, high-spectral-resolution Cassini/CIRS observations from October 2005 through April 2009 are used to study whether there is an observable increase in upper tropospheric acetylene in regions of known normal thunderstorm activity. Using both individual measurements in which there is known thunderstorm activity, as well as large coadditions of data to study latitudinal-dependencies over the full disc, no systematic enhancement in upper tropospheric (100 mbar) C_2H_2 was detected around regions in which there are known occurrences of normally sized (2000 km) thunderstorms, or in normally sized thunderstorm-prone regions such as 40°S. It is likely that the magnitude of the enhancement theorised is too generous or that enhancements are not adverted into the upper troposphere as vertical mixing rates in models would suggest, since Cassini/ CIRS can only detect C_2H_2 above the 200 mbar level-although the massive northern hemisphere thunderstorm of 2010/2011 seems able to decrease stratospheric concentrations of C_2H_2. From this, it can be asserted that lightning from normal thunderstorm activity cannot be the key source for upper tropospheric C_2H_2 on Saturn, since the upper-tropospheric concentrations retrieved agree with the concentrations stemming from the photolysis of CH_4 (2-3 ppbv) from solar radiation penetrating through the Saturnian atmosphere, with an upper limit for lightning-induced C_2H_2 volume mixing ratio of 10~(-9).
机译：土星上的雷暴活动是通过雷电释放的无线电辐射以及对地球夜间的闪电的光学探测而观察到的。雷暴提供了一种极端的环境，在这种环境中，可以诱发特定的大气化学作用，即通过闪电放电释放能量，以及快速的垂直运输导致对流层物质的快速平流。因此，理论认为，某些大的大气痕量物种（例如C_2H_2，HCN和CO）可以通过闪电形式的大能量爆发在对流层中产生，并通过雷暴的极端动力向上迁移到对流层上层，卫星仪器应观测到的位置。在这项工作中，使用2005年10月至2009年4月的高分辨率卡西尼/ CIRS观测资料研究了在已知正常雷暴活动区域中对流层上乙炔的增加是否可观察到的现象。使用已知雷暴活动的单独测量结果以及大量数据加在一起研究整个磁盘上的纬度相关性，在已知发生区域附近未发现对流层上层（100 mbar）C_2H_2的系统增强通常大小（2000 km）的雷暴，或通常容易发生雷暴的地区（例如40°S）。从理论上讲，这种增强作用的幅度可能过大，或者增强作用没有像模型中的垂直混合速率所暗示的那样被引入对流层上部，因为卡西尼/ CIRS只能检测到200 mbar以上的C_2H_2，尽管北部是巨大的2010/2011年的半球雷暴似乎能够降低平流层C_2H_2的浓度。由此可以断定，正常的雷暴活动产生的闪电不能成为土星上对流层C_2H_2的主要来源，因为所获得的对流层上层浓度与太阳光对CH_4（2-3 ppbv）的光解所产生的浓度一致。辐射穿过土星大气，雷电引起的C_2H_2体积混合比上限为10〜（-9）。

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  • 来源
    《Planetary and space science》 |2012年第1期|p.21-37|共17页
  • 作者

    J. Hurley; P.G.J. Irwin; L.N. Fletcher; J.I. Moses; B. Hesman; J. Sinclair; C. Merlet;

  • 作者单位

    Atmospheric, Oceanic & Planetary Physics, Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford 0X1 3PU, UK;

    Atmospheric, Oceanic & Planetary Physics, Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford 0X1 3PU, UK;

    Atmospheric, Oceanic & Planetary Physics, Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford 0X1 3PU, UK;

    Space Science Institute, 1602 Old Orchard Ln, Seabrook, TX 77586, USA;

    NASA/Goddard Spaceflight Center, Creenbelt, MD 20771, USA;

    Atmospheric, Oceanic & Planetary Physics, Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford 0X1 3PU, UK;

    Atmospheric, Oceanic & Planetary Physics, Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford 0X1 3PU, UK;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    saturn; atmospheres; acetylene; infrared; lightning; optimal-estimation;

    机译：土星气氛;乙炔;红外线;闪电;最优估计;

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