The global distribution of surficial hydroxyl on the Moon is hypothesized to be derived from the implantation of solar wind protons. As the Moon traverses the geomagnetic tail, it is generally shielded from the solar wind; therefore, the concentration of hydrogen is expected to decrease during full Moon. A Monte Carlo approach is used to model the diffusion of implanted hydrogen atoms in the regolith as they form metastable bonds with O atoms, and the subsequent degassing of H₂ into the exosphere. We quantify the expected change in the surface OH and the H₂ exosphere using averaged SW proton flux obtained from the Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) measurements. At lunar local noon, there is a small difference <∼10 ppm between the surface concentrations in the tail compared to out. However, the cumulative effect of traversing the magnetotail is a surface concentration depleted by ∼60 ppm for a region of the surface that spends most of its time in the lunar wake (waning gibbous to waxing crescent) on the nightside during time periods when Moon is exposed to unperturbed solar wind. The H₂ exosphere decreased by approximately an order of magnitude while in the magnetotail due to the decreased proton flux. The model results are consistent with preliminary exospheric observations obtained by both the (Lyman Alpha Mapping Project on the Lunar Reconnaissance Orbiter) LAMP observations and mass spectrometer measurements by the Chandrayaan‐I Altitudinal Composition Explorer (CHACE).

中文翻译：

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磁层屏蔽对月球氢循环的影响

据推测，月球表面羟基的全球分布是由太阳风质子的注入引起的。当月球横穿地磁尾巴时，通常会受到太阳风的遮挡。因此，预计在满月期间氢的浓度会降低。蒙特卡洛方法用于模拟注入的氢原子在重晶石中的扩散，因为它们与O原子形成了亚稳键，随后将H ₂脱气至外层。我们量化表面OH和H ₂的预期变化使用从加速，重新连接，湍流和月球与太阳的相互作用的电动力学（ARTEMIS）测量中获得的平均SW质子通量计算出的外层。在农历当地正午，与外面相比，尾巴中的表面浓度之间有一个很小的差异（约10 ppm）。但是，遍历磁尾的累积效应是，在月亮升空的时间段的大部分时间，它在月球上度过了大部分时间（在晚月渐渐向蜡状新月形凸起），该区域的表面区域消耗了约60 ppm的表面浓度。暴露在不受干扰的太阳风中。H ₂由于质子通量的减少，在磁尾中，外气层减少了大约一个数量级。该模型的结果与（月球侦察轨道器的莱曼阿尔法测绘项目）LAMP观测和Chandrayaan-I垂直成分探测器（CHACE）进行的质谱仪测量所获得的初步大气圈观测结果一致。