The diurnal variation and distribution of lunar surficial hydration (OH/H₂O) is of great significance for understanding the solar wind implantation and water cycle on the Moon. Lunar south pole is an ideal place to study the diurnal variation of surficial hydration due to the large number of repeat observations of the same region, which is very limited in mid- or low-latitudes. Here we showed clear 0.5-hr interval diurnal variation of surficial hydration at lunar south pole. The variation of hydration band depth with local time is exactly the opposite to the variation of temperature, indicating that lunar surficial hydration changes sufficiently with temperature. This relationship indicates that both the diurnal variation and hydration content are latitude dependent. Our observations support the hypothesis that the diurnal variation of hydration on the Moon is due to the formation of metastable hydroxyl.

中文翻译：

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月球南极水循环和水资源：月球矿物学制图仪重复观测中表面水合作用的日间和空间变化

_{月球表面水化(OH/H 2} O)的日变化和分布对于了解太阳风在月球的植入和水循环具有重要意义。月球南极是研究地表水合作用日变化的理想场所，因为对同一地区进行了大量的重复观测，而中低纬度地区的重复观测非常有限。在这里，我们显示了月球南极表面水合作用的清晰的 0.5 小时间隔的日变化。水化带深度随当地时间的变化与温度的变化正好相反，表明月球表面水化随温度的变化充分。这种关系表明昼夜变化和水合含量均取决于纬度。我们的观察结果支持这样的假设：月球上水合的昼夜变化是由于亚稳态羟基的形成造成的。