A new approach for modelling chromospheric evaporation in response to enhanced coronal heating - II. Non-uniform heating
A new approach for modelling chromospheric evaporation in response to enhanced coronal heating - II. Non-uniform heating
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模拟日冕加热增强的色球蒸发的新方法 - II。
DOI：
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发表时间：
2017
期刊：
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通讯作者：
I. Moortel
中科院分区：
文献类型：
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作者：
C. Johnston;A. Hood;P. Cargill;I. Moortel
我们建议，使用近似的“跳跃条件”在太阳过渡区允许快速和准确的数值解的一维流体动力学方程时，日冕经历脉冲加热。特别是，它消除了对高度分辨率的数值网格所施加的非常短的时间步长的需要。本文提出了进一步的例子，该方法的适用性的情况下，不均匀的加热，特别是，nanoflare列车（均匀的空间，但不均匀的时间）和空间局部脉冲加热，包括在环顶点和基地的过渡区。在所有情况下，日冕密度和温度的整体行为显示出良好的协议与完全解决的一维模型，是显着优于从一个一维代码运行的等效结果，而不使用跳跃条件，但具有相同的粗网格。本文对跳跃条件引入的误差作了详细的分析，指出与完全分辨的编码不一致的原因是：（1）忽略了与大气总能量变化率相应的项;（ii）在过渡区底部的质量运动，以及（iii）对于某些具有足点加热的情况，过度估计过渡区的辐射损失。
We proposed that the use of an approximate “jump condition” at the solar transition region permits fast and accurate numerical solutions of the one dimensional hydrodynamic equations when the corona undergoes impulsive heating. In particular, it eliminates the need for the very short timesteps imposed by a highly resolved numerical grid. This paper presents further examples of the applicability of the method for cases of non-uniform heating, in particular, nanoflare trains (uniform in space but non-uniform in time) and spatially localised impulsive heating, including at the loop apex and base of the transition region. In all cases the overall behaviour of the coronal density and temperature shows good agreement with a fully resolved one dimensional model and is significantly better than the equivalent results from a 1D code run without using the jump condition but with the same coarse grid. A detailed assessment of the errors introduced by the jump condition is presented showing that the causes of discrepancy with the fully resolved code are (i) the neglect of the terms corresponding to the rate of change of total energy in the unresolved atmosphere; (ii) mass motions at the base of the transition region and (iii) for some cases with footpoint heating, an over-estimation of the radiative losses in the transition region.