Hemispheric injection of magnetic helicity by surface flux transport
Hemispheric injection of magnetic helicity by surface flux transport
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DOI：
10.1051/0004-6361/201936475
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发表时间：
2019-11
影响因子：
6.5
通讯作者：
G. Hawkes;A. Yeates
中科院分区：
文献类型：
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作者：
G. Hawkes;A. Yeates
目标。我们估计了27个太阳活动周（1700-2009）中通过表面通量输运注入太阳大气的相对磁螺旋度。方法.我们确定的径向磁场的演变，使用两个单独的表面通量输运模型：一个驱动的磁记录输入和另一个统计活动区插入引导的太阳黑子数记录。注入的相对磁螺旋度，然后计算从这个径向磁场与已知的电场中的通量传输模型。结果忽略通量出现，太阳自转是螺旋度注入的主要贡献者。在高纬度地区，注入总是负/正的北方/南半球，而在低纬度地区的注入往往有相反的符号时，整合了整个太阳活动周期。在一个给定的太阳活动周期中，总的螺旋度注入取决于这两种贡献之间的平衡。这个净注入螺旋度与周期结束时的轴向偶极矩很好地相关。
Aims. We estimate the injection of relative magnetic helicity into the solar atmosphere by surface flux transport over 27 solar cycles (1700–2009). Methods. We determine the radial magnetic field evolution using two separate surface flux transport models: one driven by magnetogram inputs and another by statistical active region insertion guided by the sunspot number record. The injection of relative magnetic helicity is then computed from this radial magnetic field together with the known electric field in the flux transport models. Results. Neglecting flux emergence, solar rotation is the dominant contributor to the helicity injection. At high latitudes, the injection is always negative/positive in the northern/southern hemisphere, while at low latitudes the injection tends to have the opposite sign when integrated over the full solar cycle. The overall helicity injection in a given solar cycle depends on the balance between these two contributions. This net injected helicity correlates well with the end-of-cycle axial dipole moment.