Moisture Sources and Climatic Controls of Precipitation Stable Isotopes Over the Tibetan Plateau in Water‐Tagging Simulations
Wenmin Man, Tianjun Zhou, Jie Jiang, Meng Zuo, Jun Hu
Abstract
Abstract Understanding the climate controls of precipitation δ 18 O in the Tibetan Plateau (TP) is crucial for paleoclimate reconstructions from a wealth of regional archives. We use the outputs of iCAM5 model to quantify the different moisture contribution to local precipitation δ 18 O and to understand the climate controls of precipitation δ 18 O in the TP based on water‐tagging. The model shows some deficiencies in simulating the spatial and temporal characteristics of precipitation δ 18 O and the local climatic controls across the TP. Among all the tagged source regions, South Asia and the Indian Ocean contribute the most to the precipitation δ 18 O in the monsoon‐controlled domain, followed by the East Asia source region. The westerlies are identified as major moisture sources to the precipitation δ 18 O in the westerlies‐controlled domain. South Asia and the Indian Ocean also contribute substantially for the westerlies‐controlled domain. On interannual time scales, summer precipitation δ 18 O in the monsoon‐controlled domain is dominated by rainout processes occurring along the moisture transport pathway, indicating that precipitation δ 18 O variations here potentially record changes in the regional upstream convection. The δ 18 O signal can be altered by changes in the moisture source location, which implies that enhanced moisture delivery from remote source regions leads to more negative precipitation δ 18 O due to an increase in the rainout effect during transport. Our results have implications for the interpretation of past variations of archives with precipitation stable isotopes, such as ice cores, tree rings, lake sediments, and speleothems in the TP and surrounding regions.