概括
先金星轨道卫星的数据显示,金星上的原子氧气大气密度低于预期,夜间外层温度令人惊地低. 周期性振荡表明行星波影响热层和外层.
科学领域:
- 行星科学 行星科学
- 大气物理学 大气物理学
- 航空学是航空学的.
背景情况:
- 卫星阻力测量提供了对上层大气条件的洞察力.
- 之前的模型预测了金星上更密集的原子氧气氛和夜间氧气膨胀.
研究的目的:
- 分析来自先金星轨道器的卫星拖动数据,以了解金星的夜间大气层.
- 为了调查观察到和预测到的大气密度和温度之间的差异.
- 为了确定金星热层和外层周期性振荡的原因.
主要方法:
- 来自维纳斯轨道探测器Pioneer的轨道衰变数据的分析.
- 从阻力测量中推断大气密度和外层温度.
- 观察数据与大气模型的比较.
- 识别不同高度的周期变化及其幅度.
主要成果:
- 在155公里处观察到的原子氧密度比预期的低一级.
- 夜间的外层温度平均低至110K.
- 大气密度从白天到晚上急剧下降,这与预测的氧气膨胀相矛盾.
- 检测到密度和温度的大型周期性振荡 (周期为5-6天).
- 温度振荡幅度随着高度的增加 (在70公里处1K,在90公里处3K,在155公里处40K).
- 夜间的外层温度是不对称的,在早上最小化.
结论:
- 观察到的低密度和低温度表明,在傍晚的终结器或强大的夜间散热器中运输效率低下.
- 周期性变化很可能是由来自平流层的行星规模波浪向上传播引起的.
- 这些发现挑战了有关金星上层大气动态和热量转移的现有模型.
- 热层和外层的超旋转是一种需要进一步研究的可能性.
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