Analytic modeling of recurrent Forbush decreases caused by corotating interaction regions
Analytic modeling of recurrent Forbush decreases caused by corotating interaction regions
复制标题
由共旋转相互作用区域引起的循环 Forbush 减少的分析模型
DOI：
10.1051/0004-6361/202140846
复制
发表时间：
2022
影响因子：
6.5
通讯作者：
M. Heber
中科院分区：
文献类型：
--
作者：
Vršnak;Dumbović ;M. Heber
在日尺度上，星系宇宙射线（GCR）通量受到日冕物质抛射和旋转相互作用区域（CIRs）的影响，分别导致所谓的Forbush减小和经常性Forbush减小（rfd）。目的：我们解释了由日冕洞发出的太阳风高速流（hss）产生的CIRs引起的约1au记录的RFDs的特性和行为。方法采用基于Fokker-Planck方程的对流-扩散GCR传播模型，并将其应用于1 au处的太阳风和行星际磁场特性。结果我们的分析表明，只有两种效应与观测结果的合理整体解释有关，即由高通量钢速度增加引起的对流效应增强，以及由磁场增强及其在CIR和高通量钢结构内的波动引起的扩散效应减弱。我们在模型中考虑的这两种效应不仅足以解释RFD的主要特征，还足以解释RFD剖面中有时观察到的“过度恢复”和二次下降。通过将我们的模型应用于2007-2008年间27次循环的长周期CIR观测，对对流-扩散GCR传播假说的解释进行了检验。结论sour分析表明模型结果与观测值吻合较好。
ContextOn scales of days, the galactic cosmic ray (GCR) flux is affected by coronal mass ejections and corotating interaction regions (CIRs), causing so-called Forbush decreases and recurrent Forbush decreases (RFDs), respectively.AimsWe explain the properties and behavior of RFDs recorded at about 1 au that are caused by CIRs generated by solar wind high-speed streams (HSSs) that emanate from coronal holes.MethodsWe employed a convection-diffusion GCR propagation model based on the Fokker-Planck equation and applied it to solar wind and interplanetary magnetic field properties at 1 au.ResultsOur analysis shows that the only two effects that are relevant for a plausible overall explanation of the observations are the enhanced convection effect caused by the increased velocity of the HSS and the reduced diffusion effect caused by the enhanced magnetic field and its fluctuations within the CIR and HSS structure. These two effects that we considered in the model are sufficient to explain not only the main signatures of RFDs, but also the sometimes observed “over-recovery” and secondary dips in RFD profiles. The explanation in terms of the convection-diffusion GCR propagation hypothesis is tested by applying our model to the observations of a long-lived CIR that recurred over 27 rotations in 2007–2008.ConclusionsOur analysis demonstrates a very good match of the model results and observations.