Abstract: Precipitation isotopologues recorded in natural archives from the southern Tibetan Plateau may document past variations of Indian monsoon intensity. The exact processes controlling the variability of precipitation isotopologue composition must therefore first be deciphered and understood. This study investigates how atmospheric convection affects the summer variability of δ18O in precipitation (δ^(18)Op) and δD in water vapor (δD_v) at the daily scale. This is achieved using isotopic data from precipitation samples at Lhasa, isotopic measurements of water vapor retrieved from satellites (Tropospheric Emission Spectrometer (TES), GOSAT) and atmospheric general circulation modeling. We reveal that both δ^(18)O_p and δD_v at Lhasa are well correlated with upstream convective activity, especially above northern India. First, during days of strong convection, northern India surface air contains large amounts of vapor with relatively low δD_v. Second, when this low‐δD_v moisture is uplifted toward southern Tibet, this initial depletion in HDO is further amplified by Rayleigh distillation as the vapor moves over the Himalayan. The intraseasonal variability of the isotopologue composition of vapor and precipitation over the southern Tibetan Plateau results from these processes occurring during air mass transportation. ; © 2015. American Geophysical Union. Received 23 JUN 2014. Accepted 1 APR 2015. Accepted article online 7 APR 2015. Published online 11 MAY 2015. This work is supported by CAS Strategic Priority Research Program(B)‐Interactions among Multiple Geo‐spheres on Tibetan Plateau and their Resource‐Environment Effects (grant XDB03030100), by the National Natural Science Foundation of China (grants 41471053 and 41190080), and by the China‐France Caiyuanpei Program. This work was finished in Laboratoire de Météorologie Dynamique, Institut Pierre Simon Laplace, CNRS, Paris, France. LMDZ simulations were performed on the supercomputer of the IDRIS computing center. Part of this research was carried out at the Jet ...
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