Cosmic ray modulation and radiation dose of aircrews during the solar cycle 24/25
Cosmic ray modulation and radiation dose of aircrews during the solar cycle 24/25
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DOI：
10.1002/2016sw001588
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发表时间：
2017-04-01
影响因子：
3.7
通讯作者：
Sato, Tatsuhiko
中科院分区：
文献类型：
--
作者：
Miyake, Shoko;Kataoka, Ryuho;Sato, Tatsuhiko
最近的观测表明，太阳活动水平下降，这从质量上预测了即将到来的太阳活动周期期间太阳活动减弱和宇宙射线通量增加。利用宇宙线调制的时间相关三维模型，预测了飞行高度的宇宙线调制和由此产生的辐射照射量。我们的银河宇宙线（GCR）模型是基于太阳风速度、日球磁场强度和日球电流片倾角的变化。考虑GCR的梯度曲率漂移运动，我们再现了1980 - 2015年宇宙线调制的22年变化。由我们的模型得到的GCR质子的能谱与超导磁刚度谱仪（BESS）和反物质物质探测和轻核天体物理学有效载荷（PAMELA）的观测结果一致，除了在太阳活动最大时的差异。在太阳活动24/25周的太阳活动极小期附近，5年的年辐射剂量将比上一个太阳活动周高出约19%。这是由宇宙射线调制的电荷符号依赖性引起的，例如正极性中的平顶轮廓。
Weak solar activity and high cosmic ray flux during the coming solar cycle are qualitatively anticipated by the recent observations that show the decline in the solar activity levels. We predict the cosmic ray modulation and resultant radiation exposure at flight altitude by using the time-dependent and three-dimensional model of the cosmic ray modulation. Our galactic cosmic ray (GCR) model is based on the variations of the solar wind speed, the strength of the heliospheric magnetic field, and the tilt angle of the heliospheric current sheet. We reproduce the 22 year variation of the cosmic ray modulation from 1980 to 2015 taking into account the gradient-curvature drift motion of GCRs. The energy spectra of GCR protons obtained by our model show good agreement with the observations by the Balloon-borne Experiment with a Superconducting magnetic rigidity Spectrometer (BESS) and the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) except for a discrepancy at the solar maximum. Five-year annual radiation dose around the solar minimum at the solar cycle 24/25 will be approximately 19% higher than that in the last cycle. This is caused by the charge sign dependence of the cosmic ray modulation, such as the flattop profiles in a positive polarity.