Observation of the atmospheric water vapor stable isotopes in three dimensions over the Tibetan Plateau

Abstract

The Third Pole with an average of 4 km above sea level, centered on the Tibetan Plateau and covered the surrounding regions, has gained growing attention as the Arctic and Antarctic, due to the largest store of water in the low latitude regions. In the past half-century, the fast and gigantic glacier retreating has changed the water supply for billions of people and increased the hazards of flood. The change of water in the interior third pole also alters the regional water cycle and ecological system. Moisture transport is a crucial process within the water cycle over the Tibetan Plateau. Atmospheric water vapor stable isotopes is a state-of-the-art tool to understand the moisture transport processes and mechanisms. In this paper, we describe the techniques for measuring water vapor stable isotopes and review the past studies of in-situ vertical profile measurements. With the strong support of the Second Tibetan Plateau Scientific Expedition and Research (STEP) project, we combine water vapor stable isotopes observations from a network of ground stations across the Third Pole (the largest observation network of instruments including nine running sites) with cutting edge tethered balloon measurements. In order to fully resolve the moisture transport across the Tibetan Plateau, collaboration among multiple disciplines is strongly needed in this study, and the extended monitoring of atmospheric water vapor stable isotopes in three dimensions (horizontally and vertically) is necessary for better understanding the moisture transport to the Tibetan Plateau. A new Earth System model that is appropriate for the water cycle over the Tibetan Plateau must be developed, representing the atmosphere, cryosphere, hydrosphere and biosphere of this unique region, and their interactions, at very high resolution, including the representation of water stable isotopes, aerosols and biogeochemical cycles. Such model would be able to quantify changes in Tibetan water cycle and servicing the regional strategies for water security and management.