Water (OH/H₂O) content variations of three targets within the lunar hourly time interval (10:00–11:00 a.m.). The bottom axis is the UTC epoch in hours past t₀, while the top axis shows the corresponding lunar LST at the Chang’e-6 landing site. The estimated water contents are marked with the red values in ppm. (a) Target-A with four measurements (D14, D19, D20, D23 in order). We used the first three data to calculate the apparent desorption activation energy (E_d) of water molecules (see Section 3). (b) Target-B with two measurements (D06, D18 in order). (c) Target-C with two measurements (D08, D21 in order).