Collaborative H-alpha and Radar Measurements of the Coupled Exosphere, Thermosphere and Ionosphere

耦合外逸层、热层和电离层的 H-alpha 和雷达协作测量

• 批准号: 8800092
• 负责人: Ronald Reynolds
• 金额: $ 27.67万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-04-15 至 1992-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8800092&HistoricalAwards=false
• 关键词: Collaborative; alpha; Radar; Measurements; Coupled

The outermost atmosphere of the earth consists of hydrogen, the lightest gas, which is produced by the dissociation of water vapor and methane in the altitudes of above 500km, where the H atoms travel on free ballistic orbits out to distances of as much as 10 earth radii before returning. Some of the H atoms have sufficient energy to escape the earth completely, and it is in this way that the primitive earth lost the large amounts of hydrogen to make possible the present oxygen rich atmosphere. The hydrogen provides a background medium through which energetic charges particles trapped in the earth's magnetic field (the ring current and Van Allen belts) travel, and collisions with the H atoms are the main loss process for the trapped ions energized during magnetic storms. The energetic neutrals resulting from such collisions travel on straight line trajectories, and can provide, with suitable detectors, "images" of the ring current in an analogous way to photons entering a camera. Collisions with low energy ions are an important cooling process for the very numerous low energy ions that also populate the near earth space threaded by the earth's magnetic field (the Magnetosphere). Thus it is important to know the distribution of hydrogen around the earth (the Geocorona) to be able to model the interactions with the ions; interpret "images" in energetic neutrals; and quantify the escape rate. This information can be obtained by ground based observations with Fabry Perot interferometers, and a number of observers and theoreticians at three universities (Wisconsin, Michigan, and Alaska) and the Aerospace Corporation have formed a group to carry out simultaneous measurements from sites ranging from Puerto Rico to Spitzbergen, to determine the latitude variation, and the height distribution of the Hydrogen.

地球最外层的大气层由最轻的气体氢组成，它是由水蒸气和甲烷在 500 公里以上的高度分解产生的，氢原子在自由弹道轨道上飞行，最远可达 10 个地球半径的距离，然后返回。 一些氢原子有足够的能量完全逃离地球，原始地球就是这样失去了大量的氢，才使得现在的富氧大气成为可能。 氢提供了一种背景介质，地球磁场（环流和范艾伦带）中捕获的高能电荷粒子通过该介质传播，与氢原子的碰撞是磁暴期间激发的捕获离子的主要损失过程。 这种碰撞产生的高能中性粒子沿直线轨迹行进，并且可以通过合适的探测器以类似于进入相机的光子的方式提供环电流的“图像”。 与低能离子的碰撞对于大量低能离子来说是一个重要的冷却过程，这些低能离子也分布在由地球磁场（磁层）穿过的近地空间中。 因此，了解地球（地冕）周围氢的分布非常重要，以便能够模拟与离子的相互作用；用能量中性来解释“图像”；并量化逃逸率。 这些信息可以通过法布里珀罗干涉仪进行地面观测来获得，三所大学（威斯康星州、密歇根州和阿拉斯加）和航空航天公司的一些观察员和理论家已经组成了一个小组，从波多黎各到斯皮茨卑尔根群岛进行同步测量，以确定纬度变化和氢的高度分布。