Survey of upper band chorus and ECH waves: Implications for the diffuse aurora
Survey of upper band chorus and ECH waves: Implications for the diffuse aurora
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DOI：
10.1029/2009ja014230
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发表时间：
2009-07
影响因子：
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通讯作者：
N. Meredith;R. Horne;R. Thorne;R. R. Anderson-R.
中科院分区：
文献类型：
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作者：
N. Meredith;R. Horne;R. Thorne;R. R. Anderson-R.
[1]漫射极光的起源多年来一直是争议的来源。最近，鉴于大气化学的相关变化可能影响中层大气，这一问题具有了新的意义。在这里，我们使用CRRES数据来评估的重要性，上带合唱和电子回旋谐波（ECH）波的生产扩散极光。这两种波模式增加地磁活动的增加，这表明它们与增强的对流和/或亚暴活动的时期。它们仅限于近赤道区域，这将中午前的部分排除在波浪调查之外。在活跃状态下，从2100到0600 MLT，在4 < L< 7区域分别观察到幅度超过1 mV m−1的强烈ECH波和高频段合唱，分别约占20%和6%。这表明两种波模式都可以使电子处于强扩散状态，但仅在活跃条件下，而不是在所有局部时间。当波的振幅较弱时，散射率在其他时间下降到强扩散极限以下。低能量电子（100 eV < E < 30 keV）的通量也随着地磁活动的增加而增加，在地球空间中与波大致相同的区域，这表明这些电子是产生波的原因。上带合唱，ECH波，和低能量电子的模式是类似的扩散极光的全球形态，这表明这两种波模式发挥重要的作用，在生产的扩散极光。
[1] The origin of the diffuse aurora has been a source of controversy for many years. More recently, the question has taken a new significance in view of the associated changes in atmospheric chemistry which may affect the middle atmosphere. Here, we use CRRES data to assess the importance of upper band chorus and electron cyclotron harmonic (ECH) waves in the production of the diffuse aurora. Both wave modes increase with increasing geomagnetic activity, suggesting they are related to periods of enhanced convection and/or substorm activity. They are confined to the near-equatorial region, which excludes the prenoon sector from the wave survey. During active conditions, intense ECH waves and upper band chorus, with amplitudes exceeding 1 mV m−1, are observed in the region 4 < L< 7 from 2100 to 0600 MLT approximately 20% and 6% of the time, respectively. This suggests that both wave modes can put electrons on strong diffusion, but only during active conditions and not at all local times. Scattering rates fall below the strong diffusion limit at other times when the wave amplitudes are weaker. Fluxes of low energy electrons (100 eV < E < 30 keV) also increase with increasing geomagnetic activity in approximately the same region of geospace as the waves, suggesting that these electrons are responsible for the generation of the waves. The patterns of the upper band chorus, ECH waves, and low-energy electrons are similar to the global morphology of the diffuse aurora, suggesting that both wave modes play significant roles in the production of the diffuse aurora.