A Modeling Study of Precipitable Water Transport into the Arctic and Antarctic in Preindustrial and Doubled-CO2 Climates
Wednesday, 17 December 2014
Where does precipitable water in the polar regions come from and how does it get there? How does precipitable water transport into the Arctic and Antarctic vary on seasonal and inter-annual timescales? And how does the origin and transport of precipitable water differ between a preindustrial and a doubled-CO2 climate? We answer these questions and more using a state-of-the-art, fully-coupled global climate model, CESM1.2, with added CAM5 water tagging capability, in which water entering the atmosphere is tagged at its point of origin within 10º latitude bands in each of the major ocean basins and within each continental land mass. We use a transformation matrix method to identify spatially coherent precipitable water transport modes and track their relative importance over a range of time scales and climates. We find that a majority of the precipitable water in the polar regions originates in the tropics and mid-latitudes, and that the relative importance of these source regions varies both seasonally and interannually. We conclude by considering the relevance of precipitable water sources and transport to climates of the past and future, and to the phenomenon of polar amplification.