Ionization by energetic protons in Thermosphere-Ionosphere Electrodynamics General Circulation Model
Ionization by energetic protons in Thermosphere-Ionosphere Electrodynamics General Circulation Model
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热层-电离层电动力学大气环流模型中高能质子的电离
DOI：
10.1029/1999ja900374
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
D. Lummerzheim
中科院分区：
文献类型：
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作者：
M. Galand;R. Roble;D. Lummerzheim
keV能量范围内的高能质子起源于磁层并沉淀到高纬度电离层，是一种常见的极光现象，可以代表极光大气的重要能源。在描述电离层-热层相互作用的全局模型中，keV质子始终被忽略或被视为电子。在这里，我们研究了 keV 质子对行星尺度 E 区电离层和热层组成的影响。我们提出了由入射质子束引起的电子和离子生产率的参数化，作为用于全局模型的快速计算方案。假设入射质子束具有麦克斯韦分布，特征能量在 1 到 20 keV 之间。参数化根据完整的质子传输代码进行验证。通过将这些参数化的电子和离子生成速率纳入一维空间（1D-in-space）热层-电离层全球平均模型中，我们表明质子沉淀可以导致电子密度、主要离子（O2+和NO+）密度和一氧化氮密度的显着增强。结果，E区的电导率也大大增加。使用热层-电离层电动力学大气环流模型 (TIE-GCM)，我们表明，当质子沉淀添加到正常电子极光时，会导致极光椭圆区大部分区域的电子、 和 NO+ 密度大幅增加（高达 70%）。由于夜侧 NO 的寿命较长，NO 密度在更大范围内受到影响。这项关于质子对行星尺度影响的首次研究清楚地表明了极光 keV 质子对电离层和热层组成的重大影响，以及在全球模型中纳入质子降水的必要性。
Originating in the magnetosphere and precipitating into the high-latitude ionosphere, energetic protons in the keV energy range are a common auroral phenomenon and can represent an important energy source for the auroral atmosphere. In global models describing the ionosphere-thermosphere interaction, keV protons have always been neglected or treated as if they were electrons. Here we investigate the effect of keV protons on both the ionospheric and thermospheric composition in the E region on a planetary scale. We present a parameterization of electron and ion production rates induced by an incident proton beam as a fast computational scheme for use in global models. The incident proton beam is assumed to have a Maxwellian distribution with characteristic energies between 1 and 20 keV. The parameterization is validated against a full proton transport code. By including these parameterized electron and ion production rates in a one dimension-in-space (1D-in-space) Thermosphere-Ionosphere Global Mean Model, we show that proton precipitation can cause a significant enhancement of the electron density, the major ion (O2+ and NO+) densities, and the nitric oxide density. As a result, the conductivities in the E region are also greatly increased. Using the Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIE-GCM), we show that the proton precipitation, when added to the normal electron aurora, causes a large increase (up to 70%) in electron, , and NO+ densities over much of the auroral oval. The NO density is affected in a larger area owing to the long lifetime of NO on the nightside. This first study of the influence of protons on a planetary scale clearly shows the significant impact that auroral keV protons can have on the ionospheric and thermospheric composition and the need to include proton precipitation in global models.