| 基于SAMI2模式的电离层加热模拟 |
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| 引用本文： | 孟兴,方涵先,翁利斌,汪四成.基于SAMI2模式的电离层加热模拟[J].地球物理学报,2016,59(8):2747-2753. |
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| 作者姓名： | 孟兴 方涵先 翁利斌 汪四成 |
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| 作者单位： | 解放军理工大学气象海洋学院, 南京 211101 |
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| 基金项目： | 国家自然科学基金项目（40505005）资助. |
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| 摘 要： | 通过在SAMI2模式的电子能量方程中添加人工加热项,数值模拟了在加热条件下磁场线上电子温度与电子密度的扰动情况,并对比了不同加热条件下的扰动效应.结果表明,入射到电离层中的大功率无线电波与等离子体相互作用,能够有效造成整条磁场线上电子温度的升高而产生电子温度扰动,尤其是加热点处,温度可增加3倍多;由于电子温度升高,压力平衡受到破坏,引发等离子体扩散进而导致电子密度扰动;电子密度扰动使得垂直于磁场线的电子密度梯度发生变化,这有可能形成电离层管(Ionosphere duct);电子温度和电子密度的扰动幅度随着加热时间的推移而减小,即扰动逐渐趋于稳定.电子温度与密度的扰动与加热率存在一种非线性关系.
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| 关 键 词： | 温度扰动 密度扰动 电离层管 等离子体扩散 |
| 收稿时间： | 2015-03-17 |
Simulation of ionospheric heating with SAMI2 model |
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| MENG Xing,FANG Han-Xian,WENG Li-Bin,WANG Si-Cheng.Simulation of ionospheric heating with SAMI2 model[J].Chinese Journal of Geophysics,2016,59(8):2747-2753. |
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| Authors: | MENG Xing FANG Han-Xian WENG Li-Bin WANG Si-Cheng |
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| Institution: | Institute of Meteorology and Oceanography, PLA University of Science and Technology, Nanjing 211101, China |
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| Abstract: | The ionosphere is an important part of the solar-terrestrial region, and the radio wave propagation is influenced by the state of the ionosphere. The solar activity, the physical processes of magnetosphere and other natural phenomena can lead to significant ionospheric disturbances, while the artificial ionospheric modification has been gained increasing attention. To know more about the characteristic of the ionospheric heating, the disturbance amplitude of electron temperature and density along geomagnetic field line are simulated with SAMI2 model.#br#The SAMI2 model can simulate the plasma variations along entire magnetic dipole field lines, from the topside magnetosphere down to nearly the E layer. This model was developed by the Naval Research Laboratory, which describes the ionosphere containing seven ion species (H+,He+,O+,O2+,N+,N2+,NO+). The continuity and momentum equations are solved for all seven species, and the temperature equation is solved for the electrons and the species H+,He+,O+. Electron density is derived by the quasi-neutrality condition in the plasma. The SAMI2 includes ion chemistry process, horizontal wind, ion inertia, photo-transportation into the ionosphere, neutral atmosphere variations, and E×B drift of the field lines. Neutral species are provided by the empirical NRLMSIS-00 model, the neutral winds are given by HWM93 model. In this paper, a heating term has been added to the electron temperature equation in SAMI2, which is regarded as Gaussian distribution.The perturbation of the electron temperature and density can be caused by artificial heating. When the transmitter is turned on, the electron temperature increases rapidly, and the electron density decreases slowly, resulting in the pressure imbalance at the heated point.#br#The pressure imbalance can cause a pulse, which propagates along the entire magnetic field line and dissipates in the plasma ultimately. The main conclusions are as follows:(1) During the heating process, the electron temperature disturbance amplitude increases gradually, but the increment rate decreases. The distribution pattern of electron temperature is similar at each time.(2) 1/4~1 hour after stopping heating, the decrease rate of the electron temperature is similar upon the field line. But nearly 1~2.5 hours after stopping heating, the decrease rate of the electron temperature is slow in the middle of field line.(3) The electron density increases rapidly when the transmitter is turned off. After nearly 1 hour cooling, the electron density achieves about 90% of the ambient values. Then, the electron density rises slowly. After nearly 5 hours cooling, the electron density returns to ambient values.(4) When the heating rate increases, the temperature perturbation amplitude increases, but the temperature perturbation amplitude caused by unit heating rate decreases gradually. It means that the perturbation amplitude of the electron temperature has a nonlinear relationship with the heating rate. |
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| Keywords: | Temperature perturbation Density perturbation Ionosphere duct Plasma diffusion |
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