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首页> 外文期刊>Journal of Geophysical Research, A. Space Physics: JGR >MHD heliosphere with boundary conditions from a tomographic reconstruction using interplanetary scintillation data
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MHD heliosphere with boundary conditions from a tomographic reconstruction using interplanetary scintillation data

机译：具有使用行星际闪烁数据的层析成像重建的边界条件的MHD日球

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Observations of interplanetary scintillation (IPS) provide a set of data that is used in estimating the solar wind parameters with reasonably good accuracy. Various tomography techniques have been developed to deconvolve the line-of-sight integration effects ingrained in observations of IPS to improve the accuracy of solar wind reconstructions. Among those, the time-dependent tomography developed at the University of California, San Diego (UCSD) is well known for its remarkable accuracy in reproducing the solar wind speed and density at Earth by iteratively fitting a kinematic solar wind model to observations of IPS and near-Earth spacecraft measurements. However, the kinematic model gradually breaks down as the distance from the Sun increases beyond the orbit of Earth. Therefore, it would be appropriate to use a more sophisticated model, such as a magnetohydrodynamics (MHD) model, to extend the kinematic solar wind reconstruction beyond the Earth’s orbit and to the outer heliosphere. To test the suitability of this approach, we use boundary conditions provided by the UCSD time-dependent tomography to propagate the solar wind outward in a MHD model and compare the simulation results with in situ measurements and also with the corresponding kinematic solution. Interestingly, we find notable differences in proton radial velocity and number density at Earth and various locations in the inner heliosphere between the MHD results and both the in situ data and the kinematic solution. For example, at 1 AU, the MHD velocities are generally larger than the spacecraft data by up to 150 km s?1, and the amplitude of density fluctuations is also markedly larger in the MHD solution. We show that the MHD model can deliver more reasonable results at Earth with an ad hoc adjustment of the inner boundary values. However, we conclude that the MHD model using the inner boundary conditions derived from kinematic simulations has little chance to match IPS and in situ data as well as the kinematic model does unless it too is iteratively fit to the observational data and measurements.
机译：行星际闪烁（IPS）的观测提供了一组数据，这些数据可用于以相当好的精度估算太阳风参数。已经开发了各种层析成像技术来消除对IPS观测中根深蒂固的视线积分效应的卷积，以提高太阳风重建的准确性。其中，加利福尼亚大学圣地亚哥分校（UCSD）研发的时变断层扫描技术以迭代方式将运动学的太阳风模型迭代拟合到IPS和观测的观测值，从而在再现地球太阳风的速度和密度方面具有非凡的准确性。近地航天器测量。但是，随着距太阳的距离增加到地球轨道之外，运动学模型逐渐崩溃。因此，使用更复杂的模型（例如磁流体动力学（MHD）模型）将运动学上的太阳风重建范围扩展到地球轨道之外并扩展到外太阳圈是合适的。为了测试这种方法的适用性，我们使用UCSD时变层析成像技术提供的边界条件在MHD模型中向外传播太阳风，并将模拟结果与原位测量结果以及相应的运动学解决方案进行比较。有趣的是，我们发现MHD结果与原位数据和运动学解之间在质子半径速度和地球上以及内部日球层不同位置的质子径向速度和数量密度存在显着差异。例如，在1 AU时，MHD速度通常比航天器数据大150 km s？1，并且在MHD解决方案中密度波动的幅度也明显更大。我们证明，通过对内部边界值进行临时调整，MHD模型可以在地球上提供更合理的结果。但是，我们得出的结论是，使用运动学模拟得出的内部边界条件的MHD模型与IPS和运动学模型相匹配的机会很少，除非它也迭代地适合于观测数据和测量结果。

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