The Small-scale Structure of Photospheric Convection Retrieved by a Deconvolution Technique Applied to Hinode/SP Data
The Small-scale Structure of Photospheric Convection Retrieved by a Deconvolution Technique Applied to Hinode/SP Data
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DOI：
10.3847/1538-4357/aa8e44
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发表时间：
2017-09
期刊：
影响因子：
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通讯作者：
T. Oba;T. Riethmüller;S. Solanki;Y. Iida;C. Quintero Noda;T. Shimizu
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文献类型：
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作者：
T. Oba;T. Riethmüller;S. Solanki;Y. Iida;C. Quintero Noda;T. Shimizu
太阳颗粒是太阳光球层中被黑暗通道包围的明亮图案，称为颗粒间通道，是过度对流的表现。观测研究一般发现，颗粒中的上升流较强，而颗粒间通道中的下降流较弱。然而，这一趋势与数值模拟的结果不一致，在重力加减速和压力梯度的共同作用下，下行流动强于上行流动。造成这种差异的一个原因是成像仪器中发生的光学失真和光衍射和散射引起的图像退化。我们将反褶积技术应用于Hinode/SP数据，试图恢复原始的太阳场景。我们的结果表明，对流上升流和下降流都有显着的增强，尤其是后者。反褶积后，在平均几何高度约50公里处，上行流和下行流分别达到−3.0公里S−1和+3.0公里S−1的最大幅度。我们发现，反褶积后的速度分布与数值模拟得到的结果相吻合。反褶积后，从质量平衡的粗略意义上讲，整个视场的平均净视线速度接近于预期的零。
Solar granules are bright patterns surrounded by dark channels, called intergranular lanes, in the solar photosphere and are a manifestation of overshooting convection. Observational studies generally find stronger upflows in granules and weaker downflows in intergranular lanes. This trend is, however, inconsistent with the results of numerical simulations in which downflows are stronger than upflows through the joint action of gravitational acceleration/deceleration and pressure gradients. One cause of this discrepancy is the image degradation caused by optical distortion and light diffraction and scattering that takes place in an imaging instrument. We apply a deconvolution technique to Hinode/SP data in an attempt to recover the original solar scene. Our results show a significant enhancement in both the convective upflows and downflows but particularly for the latter. After deconvolution, the up- and downflows reach maximum amplitudes of −3.0 km s−1 and +3.0 km s−1 at an average geometrical height of roughly 50 km, respectively. We found that the velocity distributions after deconvolution match those derived from numerical simulations. After deconvolution, the net LOS velocity averaged over the whole field of view lies close to zero as expected in a rough sense from mass balance.